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It was hypothesised that there is a linear relationship between the severity of exercise induced calf ischaemia and the prevalence of calf claudication on a treadmill until a plateau is reached. It was expected that no pain would be present in the absence of ischaemia and all severely ischaemic calves would be symptomatic.This was a retrospective analysis of a cross sectional acquired database recording. Transcutaneous oxygen pressure (TcPOA linear relationship was found between the degree of ischaemia and the proportion of symptomatic calves for DROPm values ranging from 0 mmHg to -28 mmHg (proportion = -0.014 × DROPm + 0.32, r = 0.961, p.001). For DROPm values lower than -28 mmHg (severe ischaemia), on average one of three limbs remained asymptomatic. The biphasic relationship between DROPm and prevalence of symptoms persists after exclusion of patients with diabetes mellitus, exercise induced hypoxaemia, and no evidence of lower extremity arterial disease (LEAD).The relationship between exercise induced pain and ischaemia is biphasic with a linear increase in the proportion of symptomatic limbs with ischaemia severity, until a plateau is reached for the more severely ischaemic limbs. The presence of exercise related calf symptoms should not automatically be reported as indicating the presence of LEAD; and the absence of exercise induced symptoms is not proof that ischaemia does not occur during exercise.

There is a general underappreciation of the spectrum of obesity-related breathing disorders and their consequences. We therefore compared characteristics of obese patients with eucapnic obstructive sleep apnea (OSA), OSA with obesity-related sleep hypoventilation (ORSH) or obesity hypoventilation syndrome (OHS) to identify the major determinants of hypoventilation.In this prospective, diagnostic study (NCT04570540), obese patients with OSA, ORSH or OHS were characterized applying polysomnography with transcutaneous capnometry, blood gas analyses, bodyplethysmography and measurement of hypercapnic ventilatory response (HCVR). Pathophysiological variables known to contribute to hypoventilation and differing significantly between the groups were specified as potential independent variables in a multivariable logistic regression to identify major determinants of hypoventilation.Twenty, 43 and 19 patients were in the OSA, ORSH and OHS group, respectively. BMI was significantly lower in OSA as compared to OHS. The extent of SRBD was significantly higher in OHS as compared to OSA or ORSH. Patients with ORSH or OHS showed a significantly decreased forced expiratory volume in 1 s and forced vital capacity compared to OSA. HCVR was significantly lower in OHS and identified as the major determinant of hypoventilation in a multivariable logistic regression (Nagelkerke RAlthough there were differences in BMI, respiratory mechanics and severity of upper airway obstruction between groups, our data support HCVR as the major determinant of obesity-associated hypoventilation.

Objective To compare the potential healing prognosis of the different routine noninvasive techniques implemented in the International Working Group Diabetic Foot Guidelines with the novel use of hyperspectral imaging (HSI) in patients with diabetic foot ulcers (DFUs). Methods Twenty-one patients with active DFUs participated in this 1-year prospective study in a specialized diabetic foot unit between December 2018 and January 2020. HSI was performed at baseline to quantify tissue oxygenation and should be presented on an anatomical map by analyzing the following parameters: (1) oxygen saturation of the hemoglobin, (2) tissue hemoglobin index, (3) the near-infrared perfusion index, and (4) tissue water index. In addition, transcutaneous oxygen pressure (TcpO2), systolic toe and ankle pressures, ankle-brachial index, and toe-brachial index values were calculated for the ulcerated limb. The primary outcome measure was wound healing, defined as complete epithelization without any drainage confirmed for at least 10 days after closure was first documented at 24 weeks. Results During the follow-up period 14 patients (66.66 %) healed and 7 patients did not heal (33.3%) by 24 weeks. The TcpO2 optimal cut-off point as determined by a balance of sensitivity and specificity of 28.5 mm Hg that yielded a sensitivity of 91% and a specificity of 100%, and area under the curve of 0.989 (P = .005; 95% confidence interval [CI], 0.945-1.000). Followed by the oxygen saturation of the hemoglobin optimal cut-off point as determined by a balance of sensitivity and specificity of 48.5 mm Hg that yielded a sensitivity of 93% and a specificity of 0.71%, and area under the curve of 0.932 (P = .013; 95% CI, 0.787-1.000). The logistic regression analyses showed that TcpO2 was the only variable associated with wound healing at 24 weeks (P Conclusions The HSI was shown to be effective in the prognosis of DFU healing compared with other noninvasive test; only TcpO2 values resulted in better diagnosis potential in wound healing.

Purpose Photo-optical TCpO2 (pTCpO2) has been proposed as a new method to determine the partial oxygen pressure of the lower extremity in patients with peripheral arterial disease. It is aimed to determine the level of agreement between pTCpO2 and the traditional electro-chemical transcutaneous oxygen tension measurement (eTCpO2). Methods Eighteen patients with intermittent claudication underwent simultaneous ankle-brachial index measurement, toe-pressure, pTCpO2 and eTCpO2 tests. Oxygen tension levels were measured on anterior chest and calf prior in rest (T0), during induced ischemia (T1) and after blood flow restoration (T2). TCpO2 agreement was assessed according to the principles of Bland and Altman. Results Absolute average TCpO2 values differed between eTCpO2 and pTCpO2 for calf in T2 (38,1 mmHg (σ 14,4) vs. 49,8 (σ 22.3) with P = 0.35). The Bland-Altman plots demonstrated eTCpO2 and pTCpO2 bias of 3,7 mmHg (σ 18,8), 11,6 mmHg (σ 17,6) and 6,7 mmHg (σ 23,5) for T0, T1 and T2 for the calf. Conclusion pTCpO2 is in agreement with eTCpO2 in measuring pO2 levels of the lower extremity in rest and during induced ischemia in patients with vascular claudication. The large variability between eTCpO2 and pTCpO2 should be accounted for, while pTCpO2 values have a tendency to demonstrate higher values in comparison to eTCpO2.

Objective The aim of this study was to evaluate changes in transcutaneous oxygen pressure (tcpO2) and systolic toe pressure (TP) during endovascular intervention. Methods This was a single centre prospective, non-randomised, observational feasibility study. Patients with chronic limb threatening ischaemia (CLTI) due to infrainguinal disease scheduled for endovascular treatment were included between March 2018 and December 2019. TcpO2 was measured continuously bilaterally at foot level throughout the procedure and at follow up. Specific time points during the intervention were chosen for comparison to baseline (before arterial puncture): average tcpO2 level five minutes prior to percutaneous transluminal angioplasty (PTA); 10 minutes after PTA; and at completion. Bilateral TP was recorded using laser Doppler flowmetry before arterial puncture, at completion, and at clinical follow up. Angiograms were analysed for successful revascularisation and vascular lesions classified according to the Global Limb Anatomical Scoring System (GLASS). Rutherford and WIfI (Wound, Ischaemia, and foot Infection) classifications were registered, as well as clinical outcome. Results Twenty-one patients completed the study. Completion angiograms showed inline flow to the foot in all but two patients. Median time to follow up was 10 weeks (range 8 – 13 weeks) and all patients except one improved clinically. TcpO2 decreased during the initial stage of the intervention, from before arterial puncture to five minute average before PTA (p Conclusion TcpO2 and TP measurements are safe and feasible non-invasive techniques for haemodynamic monitoring during endovascular revascularisation. TP increased significantly immediately after completion of the successful intervention, whereas tcpO2 did not. Both TP and tcpO2 demonstrated a significant increase at the 10 week follow up.

Testing for collateral circulation of the hand before any radial artery procedure has been a subject of many controversies. Neither the Allen's test (AT) nor the plethysmography based Barbeau test, adequately and reliably test for collateral circulation. With growing interest in radial approaches for vascular procedures, its common use for arterial monitoring and blood gas sampling, there has been a growing interest in the relevance of assessing collateral hand circulation. Multiple studies now refute the utility of collateral testing, yet it continues to be propagated as an essential triaging assessment tool by educators. Allen's, or modified Allen tests (MAT) are operator dependent and often subjected to observational bias. Barbeau test is more objective, however, it fails to show added benefit in assessing pre-procedural patency. Despite studies questioning the validity of collateral circulation assessment, these tests continue to preclude radial approach. There is no standardization for being considered an abnormal test across literature and the significance of an abnormal test translating into a clinical outcome has not been investigated in prior studies. This may be attributed to the robust vascular supply of the hand, connections at the digital circulation level and vessel recruitment in an event of occlusion. We reviewed this topic extensively and make an argument that non-invasive collateral testing should be abandoned as a triage tool for radial artery procedures such as arterial punctures, arterial monitoring, and transradial vascular procedures.

Transcutaneous oxygen pressure (TcpO2) measurement has been used for years at rest in patients with lower extremity artery disease. It was proposed for exercise testing (Ex-TcpO2) in the 80ies to evaluate regional blood flow impairment (RBFI) at the proximal and distal levels simultaneously and on both sides, in case of claudication. It was suggested that the use of a chest electrode was mandatory to show that decreases in TcpO2 at the limb level result from limb RBFI and not from a systemic pO2 decrease of cardiopulmonary origin (exercise-induced hypoxemia). Unfortunately, a major pitfall of Ex-TcpO2 was the low absolute reliability of the regional perfusion index (RPI: ratio of limb to chest values) and the technique was almost abandoned until 2003, when the DROP index (Decrease from rest of oxygen pressure: limb changes minus chest changes from rest) was proposed. The DROP mathematical formula makes Tcpo2 results independent from the absolute pO2 starting values, improving reliability of Ex-TcpO2 as compared to the RPI. Since then, Ex-TcpO2 has been of renewed interest. The present paper addresses the physiology of Ex-TcpO2, interpretation of its results, and common misunderstandings about its use.

International audience; Background and aims: Transcutaneous oxygen pressure (TcpO2) is used in patients with suspected critical limb ischemia (CLI). Sinusoidal changes (SC~) in TcpO2 are found in patients with Cheyne-Stokes respiration (CSR). We aimed to determine the characteristics of TcpO2 changes at rest in patients with suspected CLI, define the objective criteria for SC ~ TcpO2 patterns (SC+), and estimate the prevalence of SC+ in our population and its impact on the outcome.Methods: We retrospectively analyzed 300 chest TcpO2 recordings performed in a 16-month period. We determined the presence/absence of SC ~ TcpO2 by visual analysis. We determined the acceptable error in the regularity of peaks of the cross-correlation with ROC curve analysis, among patients with typical SC ~ TcpO2 and non-sinusoidal patterns. Then, we defined SC + as a minimum of five peaks, a standard deviation of TcpO2 >1.25 mmHg, an error in regularity of peaks of the cross-correlation < 10%, and a cycle length between 30 and 100 s. In patients included until October 2019, we compared the outcome as a function of SC + or SC- with Cox models.Results: Mathematical detection of SC + found that 43 patients (14.3%) fulfilled all four defined criteria at the chest level, but only 23 did so at the limb level. In the follow-up of 207 patients, the presence of Sc ~ TcpO2 at the chest significantly increased the risk of mortality: hazard ratio: 2.69 [95%CI: 1.37-5.30]; p < 0.005.Conclusions: SC ~ TcpO2 is frequent, and is associated with a poor outcome in patients with suspected CLI.

Objective In this study, we aimed to evaluate the accuracy of HR and SaO2 data obtained using a smartphone compared with the measurements of a vital signs monitor (VSM) and an arterial blood gas (ABG) device, respectively. Material and methods In this single-center prospective study, the HR and SaO2 measurements were performed using the built-in sensor and light source of a Samsung Galaxy S8 smartphone and compared to the results of VSM and ABG device. The Bland-Altman analysis was used to evaluate and visualize the agreement between the methods. Results The data of 101 patients were analyzed. There was a high correlation between HR measured by smartphone and HR measured by VSM [P Conclusion The HR and SaO2 values obtained by smartphone were found to be consistent with the measurements of the reference devices. With the growing use of smartphone technology in the health field, we foresee that patients will be able to make their own triage assessment before presenting to the hospital.

Measurements of regional tissue oxygen serve as a proxy to monitor local perfusion and have the potential to guide therapeutic decisions in multiple clinical disciplines. Transcutaneous oximetry (tcpO(2)) is a commercially available noninvasive technique that uses an electrode to warm underlying skin tissue and measure the resulting oxygen tension at the skin surface. A novel approach is to directly measure interstitial tissue oxygen using subcutaneous oxygen microsensors composed of a biocompatible hydrogel carrier platform with embedded oxygen sensing molecules. After initial injection of the hydrogel into subcutaneous tissue, noninvasive optical measurements of phosphorescence-based emissions at the skin surface are used to sense oxygen in the subcutaneous interstitial space. The object of the present study was to characterize the in vivo performance of subcutaneous microsensors and compare with transcutaneous oximetry (tcpO(2)). Vascular occlusion tests were performed on the arms of 7 healthy volunteers, with repeated tests occurring 1 to 10 weeks after sensor injection, yielding 95 total tests for analysis. Comparative analysis characterized the response of both devices to decreases in tissue oxygen during occlusion and to increases in tissue oxygen following release of the occlusion. Results indicated: (I) time traces returned by microsensors and tcpO(2) were highly correlated, with the median (interquartile range) correlation coefficient of r=0.93 (0.10); (II) both microsensors and tcpO(2) sensed a statistically significant decrease in normalized oxygen during occlusion (p

Objectives To evaluate the sensitivity and specificity of a screening test panel for nocturnal hypoventilation (NH) and other sleep related respiratory events during monitoring of patients with chronic hypercapnic respiratory failure (CRF) treated with NIV. Methods We performed a prospective study at Oslo University Hospital. Eligible for inclusion were consecutive adults with CRF due to neuromuscular diseases or chest wall disorders treated with NIV scheduled for a follow-up visit. All patients underwent the screening test panel (clinical evaluation, daytime arterial blood gas (ABG), nocturnal pulse oximetry (SpO2) and data from ventilator software) and the reference tests; sleep polygraphy and nocturnal transcutaneous CO2. Results Of 67 patients included, NH was confirmed in 23–50 according to the 3 definitions used for NH, apnea-hypopnea index (AHIpolygraphy) ≥ 10 was confirmed in 16 and patient-ventilator asynchrony (PVA) ≥ 10% of total recording time in 14. Sensitivity of the combined screening test panel for NH was 87% (95% confidence interval 66–97), 84% (66–95) and 80% (66–90), for abnormal AHIpolygraphy 91% (59–100) and for PVA 71% (42–92). Sensitivity for NH of SpO2 was 48% (27–69), 39% (22–58) and 38% (24–53) and of daytime ABG 74% (52–90), 74% (55–88) and 68% (53–80). Sensitivity and specificity of AHIsoftware for AHIpolygraphy ≥ 10 was 93% (68–100) and 92% (81–98) respectively. Discussion In patients treated with long term NIV, screening test panel, nocturnal SpO2 and daytime ABG all failed to accurately detect NH, underlining the importance of nocturnal monitoring of CO2. AHIsoftware accurately identified obstructive events and can be used to modify NIV settings. Trial registration N° NCT01845233.

International audience; Exertional lower limb pain is a frequent diagnostic issue in elderly patients. Arterial claudication results from the mismatch between the oxygen requirement of, and oxygen delivery to the exercising muscles. Non-invasive vascular investigations (ultrasound imaging, plethysmography or segmental pressure) are used in routine at rest or following exercise, but none can be used during walking or to directly monitor cutaneous oxygen delivery to the limb. Here, we review the methods, tips and traps of the transcutaneous oxygen pressure measurement technique and potential applications.Transcutaneous oxygen pressure measurement is largely used in vascular medicine for patients with critical limb ischemia. It can also detect regional blood flow impairment at the proximal and distal limb simultaneously and bilaterally during exercise. Exercise-oximetry can also analyze systemic oxygen pressure changes on a reference area on the chest, to screen for occult pulmonary disease. As a surface technique, it does not directly measure muscle oxygen content but provides a reliable estimation of regional blood flow impairment.With the use of a recently reported index that is independent of the unknown transcutaneous gradient for oxygen, exercise-oximetry provides some accurate information compared to classical non-invasive vascular investigations to argue for a vascular or non-vascular origin of exertional lower limb pain during exercise. Although a time consuming technique, it is a simple test and it is progressively spreading among referral vascular centers as a useful non-invasive diagnostic tool for patients suspected of arterial claudication.

International audience; BACKGROUND: Transcutaneous oxygen pressure (tcpO2) reliability is blunted by an unpredictable transcutaneous gradient through the skin. We hypothesized that the "Decrease from Rest of Oxygen pressure (DROP: subtraction of limb-changes from chest-changes from the respective starting values) would show a good to excellent reliability during Exercise -tcpO2 investigations.METHODS: In three different experiments we tested: The intra-test variability at the peripheral level (Experiment A: 32 patients, 16 at each location), at the chest level (Experiment B: 45 patients) and the test-retest reproducibility within 3 months (Experiment C: 67 patients). We calculated the intra-class coefficient of correlation (ICC) with 95% confidence interval [Lower/upper limit]. ICC between 0.60 and 0.749 indicate a good agreement. ICC above 0.750 indicates an excellent agreement.RESULTS: ICC values for DROP-min were 0.848 [0.723/0.935] at the buttock and 0.920 [0.846/0.967] at the calf levels, in experiment A; ICC were 0.873 [0.799/0.923] at the buttock and 0.898 [0.790/0.953] at the calf levels, in experiment B; 0.806 [0.716/0.871] at then buttock level (n = 67) and 0.807 [0.722/0.868] at the calf in experiment C.CONCLUSIONS: Intra-test and test-retest reliability is excellent using the DROP calculation for exercise-tcpO2 investigations.

The aim of the present study was to determine the effect of hypercapnia on motor neuromuscular activity of the human triceps surae muscle. Nine subjects participated in trials in a normal breathing condition and a CO2 rebreathing condition. In both conditions, in order to provoke self-sustained muscle activity, percutaneous electrical train stimulation was applied to the tibial nerve while each subject lay on a bed. Self-sustained muscle activity, which is an indirect observation of plateau potentials in spinal motoneurons, was measured for 30 s after the train stimulation by using surface electromyography. The sustained muscle activity was increased by CO2 rebreathing (P < 0.05). This finding suggests that motor neuromuscular activity may be linked to the respiratory system that is activated during hypercapnia.

To determine, as part of our Utah Newborn Nursery Bilirubin Management Program, whether end-tidal carbon monoxide concentration (ETCOc) measurements in all newborns in our nursery receiving phototherapy were associated with outcomes related to the management of hyperbilirubinemia, including time (hours after birth) when phototherapy was initiated, total duration of phototherapy during the nursery stay, repeat phototherapy treatments, and hospital readmission for phototherapy.We performed a planned interim analysis of a component of our program in which we measured ETCOc noninvasively using CoSense on each newborn in our nursery receiving phototherapy and recorded specific outcomes related to phototherapy management.Of 1856 newborns admitted to our nursery in a 6-month period in 2020, 170 (9.8%) were treated with phototherapy. An ETCOc reading was successfully obtained in 145 of 151 attempts (96%). Higher ETCOc values were associated with earlier institution of phototherapy and longer duration of phototherapy. For every 1-ppm increase in ETCOc, phototherapy was started 9 hours earlier (95% CI, 3.3-14.8; P = .002) and was administered for an additional 9.3 hours (95% CI, 4.1-14.6; P .001). Three newborns were readmitted to the hospital for intensive phototherapy; while in the nursery, all 3 had an elevated ETCOc (2.2, 2.6, and 2.9 ppm).Our findings provide answers to questions raised in the 2004 American Academy of Pediatrics bilirubin guidelines. In our neonatal nursery, measuring ETCOc in all phototherapy recipients was feasible and safe, and the results were associated with multiple aspects of phototherapy management. Higher ETCOc values predicted earlier and longer phototherapy courses.

Objective Elevated plasma levels of lipoprotein(a) [Lp(a)], referred to as lipoprotein(a)-hyperlipoproteinemia [Lp(a)-HLP], are an independent risk factor for atherosclerosis. Lipoprotein apheresis (LA) enables an effective reduction of Lp(a) plasma levels. The present study investigates the effects of LA in patients with Lp(a)-HLP and peripheral artery disease (PAD). Methods Ten patients with isolated Lp(a)-HLP and severe PAD and who had recently undergone a revascularization (index procedure) were prospectively included in this observational single center study. All patients received weekly LA. Ankle-brachial-index (ABI), transcutaneous partial oxygen pressure (tcpO2), pain level, and walking distance were assessed at baseline and at the follow ups scheduled 1, 3, 6, 12, and 24 months after initiation of LA. The number of revascularizations within 12 months prior and within 24 months after the index procedure was determined. Results As early as 1 month after initiation of LA, all investigated parameters had improved significantly compared to baseline. This improvement was further substantiated under LA throughout the entire follow-up period. Comparing baseline results with the 24-month follow-up, the average ABI increased from 0.53 ± 0.15 to 0.97 ± 0.08 (P Conclusion In patients with Lp(a)-HLP and severe PAD, LA results in sustained improvement of circulation, pain level and walking distance. The number of repeat revascularizations is strongly reduced under LA treatment.

Objective Topical negative pressure (TNP) therapy is widely used in the treatment of acute wounds in vascular patients on the basis of proposed multifactorial benefits. However, numerous recent systematic reviews have concluded that there is inadequate evidence to support its benefits at a scientific level. This study evaluated the changes in wound volume, surface area, depth, collagen deposition, and tissue oxygenation when using TNP therapy compared with traditional dressings in patients with acute high-risk foot wounds. Methods This study was performed with hospitalized vascular patients. Forty-eight patients were selected with an acute lower extremity wound after surgical debridement or minor amputation that had an adequate blood supply without requiring further surgical revascularization and were deemed suitable for TNP therapy. The 22 patients who completed the study were randomly allocated to a treatment group receiving TNP or to a control group receiving regular topical dressings. Wound volume and wound oxygenation were analyzed using a modern stereophotographic wound measurement system and a hyperspectral transcutaneous oxygenation measurement system, respectively. Laboratory analysis was conducted on wound biopsy samples to determine hydroxyproline levels, a surrogate marker to collagen. Results Differences in clinical or demographic characteristics or in the location of the foot wounds were not significant between the two groups. All patients, with the exception of two, had diabetes. The two patients who did not have diabetes had end-stage renal failure. There was no significance in the primary outcome of wound volume reduction between TNP and control patients on day 14 (44.2% and 20.9%, respectively; P = .15). Analyses of secondary outcomes showed a significant result of better healing rates in the TNP group by demonstrating a reduction in maximum wound depth at day 14 (36.0% TNP vs 17.6% control; P = .03). No significant findings were found for the other outcomes of changes in hydroxyproline levels (58.0% TNP vs 94.5% control; P = .32) or tissue perfusion by tissue oxyhemoglobin saturation (19.4% TNP vs 12.0% control; P = .07) at day 14. At 1 year of follow-up, there were no significant outcomes in the analysis of wound failure, major amputation, and overall survival rates between the two groups. Conclusions In this pilot study, applying TNP to acute high-risk foot wounds in patients with diabetes or end-stage renal failure improved the wound healing rate in reference to wound depth. This suggests that TNP may play a role in enhancing wound healing. This study sets the foundation for larger studies to evaluate the superiority of TNP over traditional dressings in high-risk foot wounds.

International audience; The number of patients suffering from peripheral arterial occlusive disease (PAOD) is growing worldwide. PAOD corresponds to an impairment of perfusion in the distal portion of some arteries that can generate critical limb ischemia. For some patients, the pathology leads to the necessity of amputation. PAOD may be diagnosed and studied with transcutaneous oxygen (tcpO2) measurements. However, the tcpO2 technique is a contact technique: probes have to be positioned on the limb, which may be impossible in case of ulcers and can lead to infection risks. We therefore herein propose to study if the laser speckle contrast imaging (LSCI) technique, an optical contactless technique, could be of interest in studying limb ischemia. For this purpose, tcpO2 and LSCI data were recorded in 48 persons suffering or not from PAOD (different levels of criticality). The LSCI data were then processed with the recently introduced bi-dimensional variational mode decomposition (2D–VMD). 2D–VMD leads to band-limited intrinsic mode functions (LSCI 2D–BLIMFs in our case). From these LSCI 2D–BLIMFs, we propose a new index. Our results show that this index and the tcpO2 values have a Pearson's r correlation coefficient of [Math Eq] . Moreover, the Bland-Altman graph shows that the LSCI 2D–BLIMFs-based index and the tcpO2 values are consistent. LSCI might therefore be of interest for a contactless study of limb ischemia.

Background Postprandial hyperglycemia is associated with impaired vascular responsiveness. Recent studies have established the use of a near-infrared spectroscopy (NIRS)-derived approach, combined with a vascular occlusion test (VOT), to examine vascular responsiveness within the microvasculature in normoglycemia. The aim of this study was to examine whether this NIRS-VOT technique could detect differences in vascular responsiveness following a hyperglycemic challenge. Methods and results Fourteen young healthy individuals participated in the study. Participants underwent five vascular occlusion tests (pre, 30, 60, 90 and 120 min after glucose ingestion). Vascular responsiveness was determined by the slope 2 of oxygen saturation (Slope 2 StO2) and the area under the curve of oxygen saturation (StO2AUC) signal. All individuals had a significant increase in blood glucose concentration after 30 min (p Conclusion This study showed that the NIRS-VOT technique is capable of detecting differential changes in vascular responsiveness to a hyperglycemic challenge, as indicated by a steeper Slope 2 StO2 and decreased StO2AUC following 90 min of an oral glucose challenge.

A 6-month-old infant with a past medical history of hypoxic ischemic encephalopathy was referred for evaluation of snoring. She was born at 41 weeks' gestational age to a 25-year-old gravida 1, para 1 mother via vacuum-assisted delivery due to cardiac decelerations. The infant's Apgar scores were 1, 4, and 6 with nuchal cord and meconium at delivery. She was started on positive-pressure ventilation but eventually required intubation at approximately 40 minutes of life. Brain MRI showed abnormal areas of restricted diffusion, involving the corpus callosum, bilateral posterior limb of the internal capsules, and possible scattered areas of frontal and occipital lobe cortices.

Background: Individuals with impaired mobility can spend prolonged periods on support surfaces, increasing their risk of developing pressure ulcers. Manufacturers have developed mattresses to maximise contact area. The present study evaluated both the biomechanical and physiological responses to lying postures on a Fluid Immersion Simulation mattress.Methods: Seventeen healthy participants were recruited to evaluate the mattress during three prescribed settings of immersion (high, medium and low). Parameters reflecting biomechanical and physiological responses, and the microclimate were monitored during three postures (supine, lateral and high-sitting) over a 90 minute test session. Transcutaneous oxygen and carbon dioxide gas responses were categorised according to three criteria and data were compared between each condition.Findings: Results indicated that interface pressures remained consistent, with peak sacral values ranging from 21 to 27 mm Hg across all immersion settings and postures. The majority of participants (82%) exhibited minimal changes in gas tensions at the sacrum during all test conditions. By contrast, three participants exhibited decreased oxygen with increased carbon dioxide tensions for all three immersion settings. Supine and high sitting sacral microclimate values ranged between 30.1–30.6 °C and 42.3–44.5% for temperature and relative humidity respectively. During lateral tilt there was a reduction of 1.7–2.5 °C and 3.3–5.3% in these values. The majority of participants reported high comfort scores, although a few experienced bottoming out during the high-sitting posture at the high immersion setting.Interpretation: Fluid Immersion Simulation provides an intelligent approach to increase the support area. Further research is required to provide evidence based guidance on the use of personalised support surfaces.

Background This study aimed to investigate the risk factors of intraoperative anesthesia adverse events (IAAEs) in children with laryngeal diseases. Methods We retrospectively recruited 118 children with laryngeal diseases who underwent surgical therapy. Based on medical history and preoperative imaging diagnosis, the baseline data, including sex, age, weight, onset age, the number of operation, the degree of airway obstruction, the nature of disease, the location of disease, complications, tracheotomy, and trachea intubation, were defined and recorded. IAAEs, such as pulse oxygen saturation (SpO 2 ) decline, heart rate (HR) decline, emergency orotracheal intubation, emergency tracheotomy, and remaining intubated postoperatively, were also recorded. The risk factors for IAAEs were identified using multivariate logistic regression model. Results Increasing severity of airway obstruction and the presence of pneumonia were risk factors for SpO 2 and HR decline in children with laryngeal diseases. Older age, supraglottic rather than subglottic disease, and trachea intubation rather than unprotected airway during surgery were protective factors for SpO 2 decline. Furthermore, severe airway obstruction increased risks of emergency orotracheal intubation and remaining intubated postoperatively, whereas supraglottic rather than subglottic disease were protective factors for emergency orotracheal intubation and remaining intubated postoperatively. Only HR decline was found to be associated with the presence of congenital heart disease. Conclusions The severe airway obstruction increases the risk of SpO 2 decline and HR decline as well as the possibility of perioperative emergency orotracheal intubation and remaining intubated postoperatively, whereas supraglottic surgery and surgery performed under endotracheal intubation reduce the incidence rates of these IAAEs in children with laryngeal diseases.

Green tea consumption has been associated with a reduction in cardiovascular disease risk factors. However, there is little evidence examining its potential differing effect between younger and older populations, whilst little is known on its effect on the circulatory system when oxygen demand is higher. Therefore the aim of this study was to evaluate the short-term effects of green tea consumption on microvascular functioning in both an older and younger population. Fifteen young [24 (4.0)] and fifteen older [61 (4.0)] participants, consumed two cups of green tea daily for 14days. We used Laser Doppler Flowmetry (LDF) to assess cutaneous microvascular function and Transcutaneous Oxygen monitoring (TcPO2) to assess skin oxygen tension. Systolic and diastolic blood pressure were also assessed on both visits. We observed significant improvements in axon-mediated microvascular vasodilation for the younger group [1.6 (0.59) vs 2.05 (0.72), p

Objective: To verify if the connection of electrodes for heart and transcutaneous oxygen monitoring interfere with the measurement of electrical bioimpedance in preterm newborns. Methods: This was a prospective, blinded, controlled, cross-sectional, crossover study that assessed and compared paired measures of resistance (R) and reactance (Xc) by BIA, obtained with and without monitoring wires attached to the preterm newborn. The measurements were performed in immediate sequence, after randomization to the presence or absence of electrodes. The sample size calculated was 114 measurements or tests with monitoring wires and 114 without monitoring wires, considering for a difference between the averages of 0.1 ohms, with an alpha error of 10% and beta error of 20%, with significance

Non-invasive transcutaneous capnometry (TcCO2) is used to assess the home ventilation's efficiency. Recently, end-tidal CO2 (ETCO2) sensors have been integrated in life-support home ventilators. The purpose of this study was to compare the ventilator-integrated ETCO2 with TcCO2, in home-ventilated neuromuscular disease patients.ETCO2 and TcCO2 were simultaneously measured during one night in 28 patients. Daytime blood gases were drawn on the following morning to measure arterial PCO2 (PaCO2).Compared to PaCO2 values, both ETCO2 and TcCO2 showed a small bias (-0.1 mmHg and 0.6 mmHg, respectively) and a similar critical difference (6.8 mmHg and 7.3 mmHg, respectively). We found a good correlation between ETCO2 and TcCO2, both considering the mean nocturnal PCO2 (r = 0.897, p 0.001; bias -1.1 [- 9.0; 6.9] mmHg) and the maximal PCO2 value over the night (r = 0.905, p 0.001; bias 3.1 [-4.5; 10.8] mmHg). The concordance of the two techniques in detecting overnight PCO2 fluctuations was high, with r = 0.919 (p 0.001) for the time spent with PCO245 mmHg and r = 0.943 (p 0.001) for the time with PCO250 mmHg.The ventilator-integrated end-tidal CO2 monitoring is as reliable as the currently used transcutaneous measurement, resulting to be a valuable proxy of the overnight PCO2 evolution. This result opens the possibility of a simplification in the monitoring of home ventilated patients, since ETCO2 measurement can be performed directly at home, with a low additional cost. However, the accuracy of both these measurement techniques is not sufficient to replace blood gases, which remain the reference examination. ClinicalTrials.gov registration:NCT02068911.

The knowledge of hemoglobin oxygen saturation (SO2) and tissue oxygenation is critical to identify the presence of shock and therapeutic options. The resonance vibrational enhancement of hemoglobin allows measurement of oxy- and deoxy species of hemoglobin and resonance Raman spectroscopy (RRS-StO2) has been successfully used to measure aggregate microvascular oxygenation. We tested the hypothesis that noninvasive oxygen saturation measured by RRS-StO2 could serve as surrogate of systemic central venous SO2.In anesthetized rats, measurements of RRS-StO2 made in oral mucosa, skin, muscle, and liver were compared with measurements of central venous SO2 using traditional multi-wavelength oximetry. Various oxygenation levels were obtained using a stepwise hemorrhage while over 100 paired blood samples and Raman-based measurements were performed. The relationships between RRS-StO2 and clinically important systemic blood parameters were also evaluated. RRS-StO2 measurements were made in 3-mm diameter tissue areas using a microvascular oximeter and a handheld probe.Significant correlations were found between venous SO2 and RRS-StO2 measurements made in the oral mucosa (r = 0.913, P0.001), skin (r = 0.499, P0.01), and liver (r = 0.611, P0.05). The mean difference between sublingual RRS-StO2 and blood sample SO2 values was 5.4 ± 1.6%. Sublingual RRS-StO2 also correlated with lactate (r = 0.909, P0.01), potassium (r = 0.757, P0.01), and pH (r = 0.703, P0.05).Raman-based oxygen saturation is a promising technique for the noninvasive evaluation of oxygenation in skin, thin tissues, and solid organs. Under certain conditions, sublingual RRS-StO2 measurements correlate with central venous SO2.

PURPOSE: This study evaluates agreement between carbon dioxide measured arterial (PaCO2) and transcutaneous (PtcCO2) over time, by repeated successive measures, taking into consideration the inherent variability of arterial measurements.METHODS AND RESULTS: 11 patients receiving LTOT, with severe to very severe COPD in a stable phase were studied. Repeated arterial blood samples were drawn and PtcCO2 measured simultaneously at the ear lobe. Bland-Altman analysis was used to evaluate 95 % limits of agreement (LoA). 194 paired samples were analysed. Following correction for bias, the difference between PaCO2 and PtCO2 during dynamic conditions was 0.02 kPa and LoA 0.94 to -0.90 kPa while 29 % of PtCO2 measurements were outside the range of variability for arterial measurements.CONCLUSION: PtcCO2 corrected for intra-patient bias provide reasonable description of PaCO2 values within but not outside steady state conditions. Our results suggest that PtcCO2 is a valuable method for monitoring in chronic rather than acute conditions when bias can be removed.

Objectives In pediatric airway surgery, SponTaneous Respiration using IntraVEnous anesthesia and Hi-flow nasal oxygen (STRIVE Hi) has not been well explored. Here, we report our experience of using STRIVE Hi in endoscopic evaluations and surgeries of the pediatric airway. Methods This retrospective review was based on 45 airway procedures conducted under STRIVE Hi, performed by a single surgeon at a single institute from May 2017 to September 2018. After induction of anesthesia, continuous infusion with propofol and remifentanil was provided to ensure an adequate level of anesthesia and supply of humidified oxygen via a nasal cannula. Monitoring was conducted using a transcutaneous CO2 sensor and a pulse oximeter, and the oxygen reserve and bispectral indexes were measured. No muscle relaxant was administered. Results The median age of the patients was 16.0 months (range: 1–215 months) and the median weight was 10.2 kg (range: 2.4–38.5 kg). The median duration of spontaneous respiration was min 40 (range: 10–140 min). The airway procedures included diagnostic microlaryngoscopy, tracheocutaneous fistula excision, balloon dilation, supraglottoplasty, laryngeal cleft repair, injection laryngoplasty, papilloma excision, and subglottic cyst removal. During these procedures, STRIVE Hi facilitated evaluation of dynamic obstruction of the airway and the immediate outcome of surgical treatment and provided a good surgical view. Intubation and the termination of spontaneous respiration were required in only five patients. Conclusions STRIVE Hi is an effective and feasible anesthesia option in pediatric airway surgery. It provides unobstructed surgical access and is applicable to a wide range of procedures.

Objective The study objective was to determine whether targeted therapy to optimize cerebral oxygenation is associated with improved neurocognitive and perioperative outcomes. Methods In a prospective trial, intraoperative cerebral oximetry monitoring using bilateral forehead probes was performed in cardiac surgical patients who were randomly assigned to an intervention group in which episodes of cerebral oxygen desaturation ( 60 consecutive seconds at either probe) triggered an intervention protocol or a control group in which the cerebral oximetry data were hidden from the clinical team, and no intervention protocol was applied. Cognitive testing was performed preoperatively and at postoperative months 3 and 6; domains studied were response speed, processing speed, attention, and memory. Perioperative outcomes studied were death, hospital length of stay, intensive care unit length of stay, postoperative day of extubation, time on mechanical ventilation, intensive care unit delirium, Sequential Organ Failure Assessment on intensive care unit admission, and intensive care unit blood transfusion. Results Group mean memory change scores were significantly better in the intervention group at 6 months (0.60 [standard error, 0.30] vs −0.17 [standard error, 0.33], adjusted P = .008). However, presence, duration, and severity of cerebral desaturation were not associated with cognitive change scores. Perioperative outcomes did not differ between the intervention and control groups. Conclusions Targeted therapy to optimize cerebral oxygenation was associated with better memory outcome in a group of cardiac surgical patients. Some aspects of the protocol other than desaturation duration and severity contributed to the observed neuroprotective effect.

Summary Background Remote ischaemic preconditioning (RIPC) protects tissues against ischaemia-reperfusion (I/R) injury, a common occurrence in several clinical settings. Aims To evaluate whether RIPC has a beneficial impact on walking disability in arterial intermittent claudication. Methods A total of 20 patients with proven intermittent claudication underwent two treadmill walking tests with a 7-day interval in between; they were randomized according to the order in which they received either RIPC or a control procedure before the first treadmill test, with a crossover at the second test. Patients received three cycles of alternating 5-minute inflation and 5-minute deflation of blood-pressure cuffs on both arms, with inflation to a pressure of 200 mmHg in the RIPC procedure or 10 mmHg in the control procedure. Walking distances and limb oxygenation data, assessed with transcutaneous oximetry and near infrared spectroscopy measurements, were obtained during both RIPC and control procedures in all patients. Results Similar exercise intensities were achieved after the control and RIPC procedures. Walking distances did not significantly differ after the control and RIPC procedures (204 [141–259] m vs 215 [162–442] m, respectively; P = 0.22). Similarly, no difference was observed in terms of transcutaneous oxygen pressure change and near infrared spectroscopy measurements during exercise between the two procedures. Conclusion RIPC did not improve walking distance or limb ischaemia variables in patients with peripheral artery disease and intermittent claudication.

Investigating new ways to deliver care, such as the use of self-service kiosks to collect and monitor signs of wellness, supports healthcare efficiency and inclusivity. Self-service kiosks offer this potential, but there is a need for solutions to meet acceptable standards, e.g. provision of accurate measurements. This study investigates the design and optimization of a prototype healthcare kiosk to collect vital signs measures. The design problem was decomposed, formalized, focused and used to generate multiple solutions. Systematic implementation and evaluation allowed for the optimization of measurement accuracy, first for individuals and then for a population. The optimized solution was tested independently to check the suitability of the methods, and quality of the solution. The process resulted in a reduction of measurement noise and an optimal fit, in terms of the positioning of measurement devices. This guaranteed the accuracy of the solution and provides a general methodology for similar design problems.

To assess the incremental value of blood oxygen saturation (SpO(2)) as a predictor in the miniPIERS model, a risk prediction model for adverse outcomes among women with a diagnosis of hypertensive disorder of pregnancy (HDP) in low-resourced settings.Using data from a prospective cohort including 852 women admitted to hospital for a HDP, the association between SpO(2) and adverse maternal outcome was assessed using logistic regression. The miniPIERS model was recalibrated and extended to include SpO(2). The incremental value of adding SpO(2) to the model was measured using a net reclassification index (NRI), sensitivity, specificity, positive and negative predictive values, and likelihood ratios.SpO(2) of93% was associated with a 30-fold increase in risk (95% CI 14 to 68) of adverse maternal outcome compared to women with SpO(2)97%. After recalibration and extension, the miniPIERS model including SpO(2) (vs. not including SpO(2)) had improved sensitivity (32.8% vs. 49.6%) at the cost of minimally decreased specificity (91.5% vs. 96.2%) with a NRI of 0.122.SpO(2) is a significant independent predictor of risk in women with a HDP. Adding SpO(2) to the miniPIERS model improved the model's ability to correctly identify high-risk patients who would benefit most from interventions.

Purpose Continuous measurement of hemoglobin by pulse CO-oximetry (SpHb; Masimo Radical 7 device, Masimo Corp, Irvine, CA) may be helpful during double-jaw surgery when massive hemorrhage is anticipated. Given the possible influence of low blood pressure on the detection of hemoglobin levels, the agreement of the SpHb was evaluated in patients undergoing orthognathic surgery when using hypotensive anesthesia. Materials and Methods Patients who underwent elective Le Fort I osteotomy and bilateral sagittal split ramus osteotomy (BSSO) were enrolled in this observational prospective cohort study. SpHb was compared with time-matched arterial total hemoglobin (tHb) before incision, at Le Fort I osteotomy, at BSSO, and at skin closure. The correlation between simultaneous SpHb and tHb measurement pairs was evaluated. Agreement was assessed by a comparison of SpHb with tHb using the intraclass correlation coefficient (ICC) and the Bland-Altman plot. Results The average age of 51 patients was 23 ± 5 years and 32 patients were male. The correlations of SpHb and tHb measurements were 0.72, 0.85, 0.89, and 0.78 before incision, at Le Fort I osteotomy, at BSSO, and at closure, respectively. Bland-Altman analysis for SpHb and tHb showed respective bias values of 0.12, 0.07, −0.09, and −0.90 g/dL. ICC values between SpHb and tHb were 0.82, 0.90, 0.91, and 0.87, respectively. Conclusions Continuous monitoring of hemoglobin may help to determine the appropriate time to perform an invasive measurement of hemoglobin in patients who undergo double-jaw surgery.

To test the hypothesis that the oximetry-derived perfusion index (PI) recorded in the index finger may provide earlier objective evidence for correct positioning of the needle tip during computed tomography (CT)-guided thoracic sympathetic blockade than skin temperature in palmar hyperhidrosis.Forty-four CT-guided thoracic sympathetic blockades were prospectively performed in both hands of 22 patients. Prior to chemical blockade, PI and skin temperature were recorded at 1 min intervals until 20 min after lidocaine injection. Repeated measures analysis of variance was used to assess the potency of PI and skin temperature over time. Using a 100% increase in the PI as the threshold and symptom relief within 20 min as the reference standard, the sensitivity and specificity for predicting a successful injection were calculated.Thirty-seven (84%) sympathetic blockade procedures were clinically successful. For successful cases, the PI increased as early as 1 min after the blockade of the sympathetic chain (p0.05), whereas the skin temperature showed statistical significance 1 min later (p0.05). The PI can be used to indicate a successful CT-guided sympathetic blockade with 97% sensitivity and 100% specificity 3 min after lidocaine injection.The PI, a more marked and sensitive indicator than changes in skin temperature, can be used to indicate a successful CT-guided sympathetic blockade with satisfying sensitivity and specificity, 3 min after lidocaine injection in palmar hyperhidrosis.

Rett syndrome (RS) is a unique X-linked dominant neurodevelopmental disorder affecting 1 in 10,000 females. Mutations in the MECP2 gene located on Xq28 have been identified. Many of the characteristic features evolve due to immaturity of the brain in RS. Cardiorespiratory function should be investigated early to characterise the clinical phenotype of the person with RS because each of the three cardiorespiratory phenotypes; apneustic, feeble and forceful breathers have unique and different management strategies. We report a case of a feeble breather showing a correlation between cortical function and tissue pO(2) and pCO(2). We conclude that subtle changes in the levels of blood gases significantly affect cortical function in RS.

The occurrence and mechanisms of nocturnal hypoxemia in precapillary pulmonary hypertension (PH) are not clearly defined.In an observational, prospective, and transversal design, we studied 46 clinically stable patients with PH and a BMI35 kg/m(2), an FEV(1)60% predicted, and idiopathic pulmonary arterial hypertension (n = 29) or chronic thromboembolic pulmonary hypertension (n = 17). They underwent nocturnal polysomnography with transcutaneous capnography.Most patients (69.6%) had New York Heart Association functional class II disease. Mean pulmonary artery pressure was 44 ± 13 mm Hg, and the cardiac index was 3.2 ± 0.6 L/min/m(2). Duration of sleep time spent with oxygen saturation as measured by pulse oximetry90% was 48.9% ± 35.9%, and 38 of 46 patients (82.6%) had nocturnal hypoxemia. Mean apnea-hypopnea index was 24.9 ± 22.1/h, and 41 patients (89%) had sleep apnea. The major mechanism of nocturnal hypoxemia was a ventilation/perfusion mismatch alone or associated with obstructive apneic events. Multivariate logistic regression identified both FEV(25%-75%) (OR, 0.9519; 95% CI, 0.9089-0.9968; P = .036) and mean pulmonary artery pressure (OR, 1.1068; 95% CI, 1.0062-1.2175; P = .037) as significant predictors of nocturnal hypoxemia. Clinical symptoms were not predictive of nocturnal hypoxemia.The occurrence of nocturnal hypoxemia is high in PH and should be screened for systematically. Further studies are needed to determine the impact of nocturnal hypoxemia on the outcome of patients with PH.ClinicalTrials.gov; No.: NCT01371669; URL: www.clinicaltrials.gov

Nano-sized titanium dioxide (TiO(2)) is among the top five widely used nanomaterials for various applications. In this study, we determine the phototoxicity of TiO(2) nanoparticles (nano-TiO(2)) with different molecular sizes and crystal forms (anatase and rutile) in human skin keratinocytes under UVA irradiation. Our results show that all nano-TiO(2) particles caused phototoxicity, as determined by the MTS assay and by cell membrane damage measured by the lactate dehydrogenase (LDH) assay, both of which were UVA dose- and nano-TiO(2) dose-dependent. The smaller the particle size of the nano-TiO(2) the higher the cell damage. The rutile form of nano-TiO(2) showed less phototoxicity than anatase nano-TiO(2). The level of photocytotoxicity and cell membrane damage is mainly dependent on the level of reactive oxygen species (ROS) production. Using polyunsaturated lipids in plasma membranes and human serum albumin as model targets, and employing electron spin resonance (ESR) oximetry and immuno-spin trapping as unique probing methods, we demonstrated that UVA irradiation of nano-TiO(2) can induce significant cell damage, mediated by lipid and protein peroxidation. These overall results suggest that nano-TiO(2) is phototoxic to human skin keratinocytes, and that this phototoxicity is mediated by ROS generated during UVA irradiation.

Objective To determine the validity of transcutaneous oximetry (TcPO 2 ) as a predictor of lower limb amputation healing complications. Design A systematic review and meta-analysis. Methods We searched five major medical databases, relevant review articles and reference lists and included all studies that evaluated TcPO 2 for its ability to predict lower limb amputation healing failure. We selected eligible articles and conducted data abstraction independently and in duplicate. Results Thirty-one studies, enrolling 1824 patients with 1960 amputations, met our inclusion criteria. Only one study reported undertaking a multivariable analysis, which demonstrated that a TcPO 2 level below 20 mmHg was an independent predictor of re-amputation occurrence (adjusted odds ratio (OR) 3.08, 95% confidence interval (CI) 1.19–7.98). Fourteen prospective cohort studies reported data that allowed for the calculation of an unadjusted relative risk of lower limb amputation healing complications leading to amputation revision associated with a TcPO 2 level below cut-offs of 10 mmHg (1.80; 95% CI 1.19–2.72), 20 mmHg (1.75; 95% CI 1.27–2.40) 30 mmHg (1.41; 95% CI 1.22–1.62) and 40 mmHg (1.24; 95% CI 1.13–1.39). Conclusions This review suggests that TcPO 2 predicts healing complications of lower limb amputations. A value of less than 40 mmHg results in a 24% increased risk of healing complication compared to over 40 mmHg and the risk further increases as the TcPO 2 decreases. There is, however, insufficient evidence to judge whether this tool adds important information beyond clinical data or to suggest an optimal threshold value. There is a need for a large, sufficiently powered study that adjusts for appropriate clinical variables.

Introduction: The aim of our study is to identify the assessment of metabolic and dynamic capillaroscopy parameters that may be predictive of the outcome of spinal cord stimulation in patients affected with non-revascularisable chronic critical limb ischemia. Materials and Methods: Forty patients, 16 female and 24 male, average age 69 8, underwent microcirculatory screening with transcutaneous oximetry and dynamic capillaroscopy. Microcirculatory assessment was performed before temporary implantation of the spinal cord stimulation stimulator and after one month. The following metabolic parameters were considered: TcPO2TcPCO2 and with dependent limb, difference between dependent limb and supine values (D TcPO2, D TcPCO2), change in TcPO2-TcPCO2 after stimulation. Dynamic capillaroscopy parameters were recorded. Follow-up visits were scheduled at three, six, and twelve months after implantation. The procedure was performed placing an Octrode (St. Jude Medical, St. Paul, MN, USA) on the dorsal columns of the spinal cord. Results: Two groups were identified on the basis of transcutaneous oximetry measurements: group A (22 patients) and group B (18 patients), responding differently to the postural test. After one month of home testing period, there was an improvement in metabolic parameters, differing from one group to the other. The morphofunctional data provided by capillaroscopy highlighted the percentage of open capillaries poststimulation as being a significant parameter, although not mentioned in previous studies. Conclusions: Spinal neuromodulation is an effective therapy option in the management of patients affected by nonreconstructable chronic critical limb ischemia.

Objective To compare the accuracy of transcutaneous (tc) to arterial partial pressure of carbon dioxide (PaCO 2 ) and partial pressure of oxygen (PaO 2 ) in anesthetized rabbits. Study design Prospective, randomized, experimental study. Animals Eight healthy adult female New Zealand white rabbits weighing 4.05 ± 0.30 kg. Methods Isoflurane anesthetized rabbits received six treatments in random order; PaCO 2 45 mmHg and PaO 2 200 mmHg. Arterial and transcutaneous measurements were taken after 15 minutes of stabilization at each condition. Linear regression, correlation and Bland-Altman analysis were performed to compare PtcCO 2 to PaCO 2 and PtcO 2 to PaO 2 . Results Over a range of measured PaCO 2 values from 21 to 67 mmHg ( n = 24) mean bias for PtcCO 2 was -1 mmHg and the 95% limits of agreement were -7 to 5 mmHg. The correlation between PtcCO 2 and PaCO 2 was strong with R 2 value of 0.9454. Over the entire range of measured PaO 2 values (46-508 mmHg) mean bias for PtcO 2 was -61 mmHg and the 95% limits of agreement were -226 to 104 mmHg. Correlation was poor with R 2 = 0.5969. Comparing PtcO 2 to PaO 2 over a narrower range [PaO 2 n = 13)] improved the correlation, with an R 2 value of 0.8518, mean bias of -7 mmHg and 95% limits of agreement from -33 to 19 mmHg. Conclusions and clinical relevance In healthy anesthetized rabbits, PtcCO 2 closely approximated PaCO 2 . In contrast PtcO 2 underestimated PaO 2 , particularly at high values. The PtcCO 2 sensor may be a useful noninvasive way to assess adequacy of ventilation in anesthetized rabbits.

Background Pandemic influenza A (H1N1) has emerged rapidly in Argentina since May 2009. Preliminary comparisons with seasonal influenza suggest that H1N1 disproportionately affects younger patients, generally causing mild disease, but in a minority of cases can be lethal. Objective The aim of this study was to develop a clinical tool for the initial management of patients with influenza-like syndrome, within the context of the novel H1N1 virus epidemic, to detect patients who need further investigation (e.g., chest X-ray study) for the diagnosis of pneumonia. Methods We prospectively studied 1090 consecutive patients with influenza-like syndrome for a period of 15 days. Based on the presence of inspiratory crackles and the level of transcutaneous pulse oximetry, we selected 217 patients requiring chest X-ray study, and pneumonia was confirmed in all of these patients. Results Among the patients with pneumonia, 132 viral diagnostic tests were available, from which specimens tested by real-time reverse-transcriptase polymerase-chain reaction (RTPCR) were positive for H1N1 in 61 patients (46%). Comparison between RTPCR-positive and RTPCR-negative patients did not show any significant difference. Eighty-seven randomly selected patients with influenza-like syndrome, but without crackles and with O 2 saturation>96%, received chest X-ray studies; none demonstrated pulmonary infiltrates. Conclusion Within the context of an influenza epidemic with the new H1N1 virus, the use of two simple and accessible clinical signs permits a rapid differentiation between those patients requiring close monitoring vs. those with mild and self-resolving disease.

Noninvasive tissue oximetry is playing an important role in postoperative monitoring of autologous tissue breast reconstruction flaps. It is increasingly being used intraoperatively to assist in perforator selection, tissue mapping, and assessment of mastectomy skin flap viability. This article reviews the use of tissue oximetry for intraoperative decision making, flap physiology, and postoperative monitoring, and also comments on common flap complications.

SummaryBackgroundPatients undergoing bronchoscopy are usually monitored only by pulse oximetry, hence hypoventilation cannot be assessed. Transcutaneous carbon dioxide tension (TcPCO2 ) monitoring is a non-invasive technique to assess hypoventilation. Patients with severe chronic obstructive pulmonary disease (COPD) undergoing bronchoscopy are at increased risk for sedation-induced hypoventilation. The aim of the study was to measure TcPCO2 using a digital sensor to examine the occurrence of hypoventilation during bronchoscopic lung volume reduction (BLVR).MethodsCombined TcPCO2 and SpO2 saturation and arterial blood gases (ABG) were prospectively measured in 15 patients with severe COPD (Mean FEV1 29%) undergoing BLVR under conscious sedation with IV midazolam and IV alfentanil.ResultsA highly significant correlation was noted between simultaneous ABG PCO2 samplings and TcPCO2 measured (R = 0.85, p 55 mmHg), observed in 7 (46%) patients, was 9 min (range 0–53).ConclusionsBronchoscopy performed under conscious sedation in patients with severe COPD is frequently associated with significant hypoventilation that can only be detected by TcPCO2 monitoring. Combined measurement of SpO2 and TcPCO2 during bronchoscopy enhances patient safety, helps guide administration of sedation, and can alert physicians to the need for anesthesia reversal following completion of bronchoscopic interventions.

Background Previous reports showed that CO 2 -insufflated colonoscopy is safe and less discomfortable. However, hypercapnia remains a vital concernment if deep sedation is necessary for difficult colonoscopy with prolonged CO 2 insufflation. This observational study is to measure bodily CO 2 subjected to colonoscopy facilitated by CO 2 - and air- or air-insufflation in conscious-sedation, deep-sedation and awake patients. Objective To investigate if CO 2 -insufflated colonoscopy could increase the risk of hypercapnia in awake, conscious-sedation and deep-sedation patients. Methods 104 patients in our health center undergoing sequential esophagogastroscopy and colonoscopy screening were included. At patients' request, incremental intravenous sedatives were given in order that the air-insufflated esophagogastroscopy could be carried out without the molestation of gag and cough reflexes. The sedation levels were re-evaluated before proceeding colonoscopy and the patients were divided into conscious-sedation (respond purposefully to verbal commands) and deep-sedation groups and randomly allocated for air or CO 2 insufflation. Transcutaneous capnography (TcCO 2 ) was recorded every minute throughout the colonoscopy procedure. Results The baseline TcCO 2 in the air- (50.9 ± 5.7 mmHg) and CO 2 -insufflated (53.1 ± 6.5 mmHg) groups under deep sedation was significantly higher than the groups under conscious-sedation and the awake groups ( p 2 -insufflation groups there were also a statistically significant ( p 2 between the start, the peak and the end of colonoscopy. TcCO 2 did not significantly change throughout the colonoscopy in awake and conscious-sedation groups, either with air or CO 2 insufflation. With deep sedation, TcCO 2 significantly increased and peaked around the time when the scope touching the cecum, and then returned to original state with suction and withdrawl of the colonoscope without significant interaction of CO 2 insufflation and deep sedation. Conclusion The TcCO 2 during colonoscopy was correlated to the data before inserting colonoscope but significantly different within awake, conscious-sedation and deep-sedation groups. TcCO 2 did not change significantly either with CO 2 insufflation or air insufflations in awake and conscious-sedation groups. However, in deep-sedation groups with significantly higher baseline TcCO 2 , further increase of TcCO 2 were significant without interaction with CO 2 insufflation. We concluded that when patients need deep sedation for colonoscopic procedures facilitated by gas insufflation, hypercapnia is still considerably present, not only with CO 2 insufflation but also with air insufflation colonoscopy.

Background Transcutaneous measurement of carbon dioxide (Tc co 2 ) provides a non-invasive estimation of arterial carbon dioxide ( P a co 2 ). Nasal capnography ( P e′ co 2 ) is used to assess ventilation during monitored anaesthesia care (MAC) with sedation since it can readily detect apnoea. We compared the agreement between Tc co 2 and P e′ co 2 with P a co 2 and the ability to detect hypercarbia in patients under deep sedation. Methods Forty healthy female subjects receiving deep sedation for hysteroscopy were studied. A Tc co 2 (TOSCA 500, Radiometer, Inc., Westlake, OH, USA) electrode was applied to the earlobe and P e′ co 2 capnography was monitored using nasal side-stream sampling. All subjects received oxygen (3 litre min −1 ). Subjects were evaluated at intervals using a modified Ramsay sedation score until they reached a score ≥5. Arterial blood gas values were compared with Tc co 2 and P e′ co 2 values. Bland–Altman, linear regression, and receiver operator characteristics analysis were performed. Results The mean (sd) absolute difference between the Tc co 2 , P e′ co 2 , and the P a co 2 were 0.43 (0.35) and 1.06 (0.8) kPa, respectively ( P =0.002). Tc co 2 demonstrated a mean bias (2 sd) of 0.23 (0.07–0.4) kPa with P a co 2 compared with −0.93 (−1.24 to −0.63) kPa for P e′ co 2 . One minute before blood sampling, the sensitivity of the Tc co 2 monitor for detecting P a co 2 >6.65 kPa was greater than for P e′ co 2 (66.7% vs 33.3%, P Conclusions Tc co 2 demonstrated better agreement with P a co 2 than P e′ co 2 for patients under MAC with deep sedation. Tc co 2 monitoring was more sensitive for detection of P a co 2 >6.65 kPa than P e′ co 2 .

Laser Doppler flowmetry (LDF) and transcutaneous oximetry (TcPO(2)) are non-invasive techniques, widely used in the clinical setting, for assessing microvascular blood flow and tissue oxygen tension, e.g. recording vascular changes after radiotherapy and hyperbaric oxygen therapy. With standardized procedures and improved reproducibility, these methods might also be applicable in longitudinal studies. The aim of this study was to evaluate the reproducibility of facial skin and gingival LDF and facial skin TcPO(2). The subjects comprised ten healthy volunteers, 5 men, aged 31-68 years. Gingival perfusion was recorded with the LDF probe fixed to a custom made, tooth-supported acrylic splint. Skin perfusion was recorded on the cheek. TcPO(2) was recorded on the forehead and cheek and in the second intercostal space. The reproducibility of LDF measurements taken after vasodilation by heat provocation was greater than for basal flow in both facial skin and mandibular gingiva. Pronounced intraday variations were observed. Interweek reproducibility assessed by intraclass correlation coefficient ranged from 0.74 to 0.96 for LDF and from 0.44 to 0.75 for TcPO(2). The results confirm acceptable reproducibility of LDF and TcPO(2) in longitudinal studies in a vascular laboratory where subjects serve as their own controls. The use of thermoprobes is recommended. Repeat measurements should be taken at the same time of day.