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An editorial is presented on the changes made in the nuclear medicine including integration of imaging technology in personalized medicine. Also discusses the use of single photon emission computed tomography (SPECT) and positron emission tomography (PET) for scans to diagnose various diseases, and its application in treatment of patients with metastatic castrate-resistant prostate carcinoma using imaging biomarkers.

Abstract: Although COVID-19 infection is associated with the increased risk of pulmonary thromboembolism (PTE), COVID-19 pulmonary lesions cause ventilation-perfusion (V/Q) patterns other than PTE. Although extensive research has been done to address different anatomical patterns of COVID-19, there is a knowledge gap in terms of V/Q lung scintigraphy in these patients. The purpose of this study is to demonstrate these patterns and to show how important it is to use SPECT/CT in addition to planar images to differentiate between these patterns from PTE. In the current collection, we presented various patterns of V/Q SPECT/CT abnormalities in COVID-19 patients., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: Computed tomography angiography (CTA) and ventilation/perfusion (V/Q) single photon emission computed tomography/CT (SPECT/CT) images have been widely used to detect PE, but few studies have performed a direct comparison between them. We aimed to evaluate the performance of these tests in the same group of patients, selected from the routine practice of a general hospital., Methods: Patients with suspected acute PE were prospectively submitted to CTA and V/Q SPECT/CT. General radiologists and nuclear physicians, respectively, interpreted the images. Data regarding age, sex, time between examinations, symptoms, and Wells score were also recorded. The final diagnosis was decided through a consensus among the clinicians, taking into account clinical, laboratory, follow-up, and all imaging procedures data., Results: Twenty-eight patients (15 male, 13 female, and median age of 51.5 years) were studied. Median duration of the onset of symptoms was 4 (1-14) days, and the median Wells score was 3.5 (1.5-6). Sensitivity, specificity, positive and negative predictive values, and accuracy were 84.6%, 80.0%, 78.6%, 85.7%, and 82.1% for V/Q SPECT/CT, and 46.1%, 100%, 100%, 68.2%, and 75.0% for CTA. The overall agreement between the methods was 57.1%. Of the 22 patients with negative CTA, 10 (45.4%) had positives V/Q SPECT/CT and seven of them classified as true positives., Conclusions: Our results suggest that V/Q SPECT/CT is more sensitive and accurate than CTA when interpreted by general radiologists and nuclear medicine physicians.

Objective: To investigate the outcomes of ventilation/perfusion scintigraphy on the diagnosis of pulmonary embolism in coronavirus disease 2019 (COVID-19) patients, we performed a systematic review of the available literature., Materials and Methods: PubMed and Scopus were systematically searched up to 4 June 2022, for relevant studies. We included studies on patients with COVID-19 who have performed ventilation/perfusion scintigraphy for diagnosis of pulmonary embolism to describe any diagnosis outcome. Irrelevant and non-English articles were excluded., Results: Overall, 27 articles were included in our review. The database search yielded studies from PubMed, Scopus, and studies identified through reviewing the reference list of included studies. Extracted information from the included studies could be categorized into several aspects: Diagnosis of pulmonary embolism with Q single-photon emission computed tomography (SPECT) CT, Tracheobronchial uptake, Diagnostic value of V/Q rather than Q at diagnosis pulmonary embolism, Different characteristics (morphological alterations) of COVID-19 in ventilation orperfusion scan, the prevalence of pulmonary embolism with Q or V/Q criteria, and Design of radiotherapy planning in lung cancer patients with COVID-19., Conclusion: Different perfusion patterns in COVID-19 are challenging but can be alleviated by adding SPECT/computed tomography (CT) to lung perfusion scans. Although perfusion only SPECT/CT can rule out or rule in others in considerable number of patients, ventilation scan is still needed in certain patients., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Ventilation and perfusion (V/Q) lung scintigraphy has been used in the assessment of patients with suspected pulmonary embolism for more than 50 y. Advances in imaging technology make SPECT and SPECT/CT feasible. This article will examine the application and technical considerations associated with performing 3-dimensional V/Q SPECT and the contribution of a coacquired CT scan. The literature tends to be mixed and contradictory in terms of appropriate investigation algorithms for pulmonary embolism. V/Q SPECT and SPECT/CT offer significant advantages over planar V/Q, with or without the advantages of Technegas ventilation, and if available should be the preferred option in the evaluation of patients with suspected pulmonary embolism., (© 2023 by the Society of Nuclear Medicine and Molecular Imaging.)

Ready access to physiologic measures, including respiratory mechanics, lung volumes, and ventilation/perfusion inhomogeneity, could optimize the clinical management of the critically ill pediatric or neonatal patient and minimize lung injury. There are many techniques for measuring respiratory function in infants and children but very limited information on the technical ease and applicability of these tests in the pediatric and neonatal intensive care unit (PICU, NICU) environments. This report summarizes the proceedings of a 2011 American Thoracic Society Workshop critically reviewing techniques available for ventilated and spontaneously breathing infants and children in the ICU. It outlines for each test how readily it is performed at the bedside and how it may impact patient management as well as indicating future areas of potential research collaboration. From expert panel discussions and literature reviews, we conclude that many of the techniques can aid in optimizing respiratory support in the PICU and NICU, quantifying the effect of therapeutic interventions, and guiding ventilator weaning and extubation. Most techniques now have commercially available equipment for the PICU and NICU, and many can generate continuous data points to help with ventilator weaning and other interventions. Technical and validation studies in the PICU and NICU are published for the majority of techniques; some have been used as outcome measures in clinical trials, but few have been assessed specifically for their ability to improve clinical outcomes. Although they show considerable promise, these techniques still require further study in the PICU and NICU together with increased availability of commercial equipment before wider incorporation into daily clinical practice. [ABSTRACT FROM AUTHOR]

Background: Chronic thromboembolic pulmonary hypertension (CTEPH) is a progressive disease. For patients with operable CTEPH, there is a clear recommendation for surgical removal of persistent thrombi by pulmonary endarterectomy (PEA). However, without the presence of PH, therapeutic management of chronic thromboembolic disease (CTED) is challenging - especially in highly trained subjects exceeding predicted values of maximal exercise capacity.Case Presentation: A 43-year-old male athlete reported with progressive exercise limitation since 8 months. Six months earlier, pulmonary embolism had occurred, and was treated since with oral anticoagulation. A pulmonary ventilation/perfusion scan showed severe ventilation/perfusion mismatch: chest CT and pulmonary angiography revealed bilateral wall-adherent thrombotic material, but pulmonary hemodynamics were completely normal. His peak oxygen uptake exceeded predicted values, however exercise ventilatory efficiency was abnormal, compared to a matching athlete. After thoroughly discussing therapeutic options with the patient, he successfully underwent pulmonary endarterectomy at an expert center. Five and twelve months after surgery, his maximal exercise capacity and ventilatory efficiency profoundly improved beyond preoperative values, and his subjective exercise tolerance had returned to normal.Conclusions: Significant CTED may be present without relevant pathologic changes in pulmonary hemodynamics at rest. Reaching normal values of maximal exercise capacity does not exclude pulmonary vascular disease in highly trained subjects. More data are needed to evaluate the risk-/benefit ratio of PEA in patients with CTED and normal pulmonary hemodynamics. A thorough discussion with the patient as well as shared decision making regarding therapy are mandatory. Cardiopulmonary exercise testing may add important clinical information in the non-invasive diagnostic evaluation at baseline and during follow-up. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to prospectively investigate clinical correlations between dosimetric parameters associated with radiation pneumonitis (RP) and functional lung imaging.Methods and Materials: Functional lung imaging was performed using four-dimensional computed tomography (4D-CT) for ventilation imaging, single-photon emission computed tomography (SPECT) for perfusion imaging, or both (V/Q-matched region). Using 4D-CT, ventilation imaging was derived from a low attenuation area according to CT numbers below different thresholds (vent-860 and -910). Perfusion imaging at the 10th, 30th, 50th, and 70th percentile perfusion levels (F10-F70) were defined as the top 10%, 30%, 50%, and 70% hyperperfused normal lung, respectively. All imaging data were incorporated into a 3D planning system to evaluate correlations between RP dosimetric parameters (where fV20 is the percentage of functional lung volume irradiated with >20 Gy, or fMLD, the mean dose administered to functional lung) and the percentage of functional lung volume. Radiation pneumonitis was evaluated using Common Terminology Criteria for Adverse Events version 4.0. Statistical significance was defined as a P value of <.05.Results: Sixty patients who underwent curative radiation therapy were enrolled (48 patients for non-small cell lung cancer, and 12 patients for small cell lung cancer). Grades 1, 2, and ≥3 RP were observed in 16, 44, and 6 patients, respectively. Significant correlations were observed between the percentage of functional lung volume and fV20 (r=0.4475 in vent-860 and 0.3508 in F30) or fMLD (r=0.4701 in vent-860 and 0.3128 in F30) in patients with grade ≥2 RP. F30∩vent-860 results exhibited stronger correlations with fV20 and fMLD in patients with grade ≥2 (r=0.5509 in fV20 and 0.5320 in fMLD) and grade ≥3 RP (r=0.8770 in fV20 and 0.8518 in fMLD).Conclusions: RP dosimetric parameters correlated significantly with functional lung imaging. [ABSTRACT FROM AUTHOR]

The injurious effects of alveolar overdistention are well accepted, and there is little debate regarding the importance of pressure and volume limitation during mechanical ventilation. The role of recruitment maneuvers is more controversial. Alveolar recruitment is desirable if it can be achieved, but the potential for recruitment is variable among patients with ARDS. A step-wise recruitment maneuver, similar to an incremental PEEP titration, is favored over sustained inflation recruitment maneuvers. Many approaches to PEEP titration have been proposed, and the best method to choose the most appropriate level for an individual patient is unclear. A PEEP level should be selected that balances alveolar recruitment against overdistention. The easiest approach to select PEEP might be according to the severity of the disease: 5-10 cm H2O PEEP in mild ARDS, 10-15 cm H2O PEEP in moderate ARDS, and 15-20 cm H2O PEEP in severe ARDS. Recruitment maneuvers and PEEP should be used within the context of lung protection and not just as a means of improving oxygenation. [ABSTRACT FROM AUTHOR]

Prone position (PP) has been used since the 1970s to treat severe hypoxemia in patients with ARDS because of its effectiveness at improving gas exchange. Compared with the supine position (SP), placing patients in PP effects a more even tidal volume distribution, in part, by reversing the vertical pleural pressure gradient, which becomes more negative in the dorsal regions. PP also improves resting lung volume in the dorsocaudal regions by reducing the superimposed pressure of both the heart and the abdomen. In contrast, pulmonary perfusion remains preferentially distributed to the dorsal lung regions, thus improving overall alveolar ventilation/perfusion relationships. Moreover, the larger tissue mass suspended from a wider dorsal chest wall effects a more homogeneous distribution of pleural pressures throughout the lung that reduces abnormal strain and stress development. This is believed to ameliorate the severity or development of ventilator-induced lung injury and may partly explain why PP reduces mortality in severe ARDS. Over 40 years of clinical trials have consistently reported improved oxygenation in approximately 70% of subjects with ARDS. Early initiation of PP is more likely to improve oxygenation than initiation during the subacute phase. Maximal oxygenation improvement occurs over a wide time frame ranging from several hours to several days. Meta-analyses of randomized controlled trials suggest that PP provides a survival advantage only in patients with relatively severe ARDS (... < 150 mm Hg). Moreover, survival is enhanced when patients are managed with a smaller tidal volume (≤8 mL/kg), higher PEEP (10-13 cm H2O), and longer duration of PP sessions (> 10-12 h/session). Combining adjunctive therapies (high PEEP, recruitment maneuvers, and inhaled vasodilators) with PP has an additive effect in improving oxygenation and may be particularly helpful in stabilizing gas exchange in very severe ARDS. [ABSTRACT FROM AUTHOR]

Background Deep vein thrombosis ( DVT) and pulmonary embolism ( PE) are connected with a poor outcome in cancer patients. We aimed to investigate the impact of cancer on the effectiveness of cardiac Troponin I ( cTnI) to predict right ventricular dysfunction ( RVD) in acute PE. Methods We retrospectively analyzed the data of 182 patients with confirmed PE. PE patients were subdivided into two groups: (i) with concomitant active cancer disease or history of cancer, and (ii) without known cancer. Receiver operating characteristic (ROC) curves with area under the curve ( AUC) was calculated for cTnI predicting RVD and related cut-off levels for both groups. Results Thirty-seven PE patients (20.3%) had an active cancer disease or a history of cancer. In contrast, 145 (79.7%) of the included PE patients did not have a known cancer disease or a history of cancer. In the PE group with cancer, analysis of the ROC curve showed an AUC of 0.76 for cTnI predicting RVD with an optimal cut-off value of 0.04 ng/mL; the risk of misclassification was 25.0%. In the PE group without cancer, AUC was 0.81 for cTnI predicting RVD with an optimal cut-off value of 0.015 ng/mL; the risk of misclassification was 24.9%. Conclusions cTnI is effective for predicting RVD in PE patients with and without cancer. However, the effectiveness of cTnI to predict RVD was higher in PE patients without cancer than in those with cancer or a history of cancer. [ABSTRACT FROM AUTHOR]

The primary task of the lungs is to maintain oxygenation of the blood and eliminate carbon dioxide through the network of capillaries alongside alveoli. This is maintained by utilising ventilatory reserve capacity and by changes in lung mechanics. Induction of anaesthesia impairs pulmonary functions by the loss of consciousness, depression of reflexes, changes in rib cage and haemodynamics. All drugs used during anaesthesia, including inhalational agents, affect pulmonary functions directly by acting on respiratory system or indirectly through their actions on other systems. Volatile anaesthetic agents have more pronounced effects on pulmonary functions compared to intravenous induction agents, leading to hypercarbia and hypoxia. The posture of the patient also leads to major changes in pulmonary functions. Anticholinergics and neuromuscular blocking agents have little effect. Analgesics and sedatives in combination with volatile anaesthetics and induction agents may exacerbate their effects. Since multiple agents are used during anaesthesia, ultimate effect may be different from when used in isolation. Literature search was done using MeSH key words 'anesthesia', 'pulmonary function', 'respiratory system' and 'anesthesia drugs and lungs' in combination in PubMed, Science Direct and Google Scholar filtered by review and research articles sorted by relevance. [ABSTRACT FROM AUTHOR]

Clinical application of anatomical and physiological knowledge of respiratory system improves patient's safety during anaesthesia. It also optimises patient's ventilatory condition and airway patency. Such knowledge has influence on airway management, lung isolation during anaesthesia, management of cases with respiratory disorders, respiratory endoluminal procedures and optimising ventilator strategies in the perioperative period. Understanding of ventilation, perfusion and their relation with each other is important for understanding respiratory physiology. Ventilation to perfusion ratio alters with anaesthesia, body position and with one-lung anaesthesia. Hypoxic pulmonary vasoconstriction, an important safety mechanism, is inhibited by majority of the anaesthetic drugs. Ventilation perfusion mismatch leads to reduced arterial oxygen concentration mainly because of early closure of airway, thus leading to decreased ventilation and atelectasis during anaesthesia. Various anaesthetic drugs alter neuronal control of the breathing and bronchomotor tone. [ABSTRACT FROM AUTHOR]

Background The natural evolution of treated symptomatic pulmonary embolism shows often incomplete resolution of pulmonary thrombi. The prevalence of perfusion defects depend on the image modality used. This study directly compares V/Q SPECT with DECT. Methods A single-center prospective observational cohort study of patients with intermediate risk PE, reassessed at the end of treatment with V/Q SPECT. Abnormal V/Q SPECT images were compared with DECT. Results We compared DECT en V/Q SPECT in 28 consecutive patients with persistent V/Q mismatch on V/Q SPECT, 13 men and 15 woman, mean age 60 ( + 17), range 23–82 year. One patient was excluded from the final analysis due to inferior quality DECT. In 18/27 (66.7%) the results were concordant between CTPA (persistent embolus visible), DECT (segmentary defects on iodine map) and V/Q SPECT (segmentary ventilation–perfusion mismatch). In 3/18 (11.1% of the total group) the partialy matched V/Q SPECT defect could be explained on DECT lung images by lung infarction. In 6/27 (22.1%) only hypoperfusion was seen on DECT iodine map. In 3/27 (11.1%) results were discordant between V/Q SPECT and DECT images. Conclusion Six months after diagnosis of first or recurrent PE, residual pulmonary perfusion-defects encountered on V/Q-SPECT corresponds in the majority of patients with chronic thromboembolic disease seen on DECT. In 22.1% of patients V/Q SPECT mismatch only corresponds with hypoperfusion on iodine map DECT scan. Some (11.1%) of the chronic thromboembolic lesions seen on V/Q SPECT can not be explained by DECT results. [ABSTRACT FROM AUTHOR]

Phosphoenolpyruvate (PEP) is an intermediate metabolite of the glycolytic pathway and an in vivo high-energy phosphate compound. We have examined the protective effects of PEP on ischemia-reperfusion lung injury in isolated rabbits lungs perfused with a physiological salt solution. The lungs were divided into three treatment groups: (1) ischemia-reperfusion (IR), (2) ischemia-reperfusion with PEP treatment (PEP-IR), in which 1 mM PEP was pre-administered into the perfusate during the stable period, and (3) ventilation-perfusion continued without interruption (Cont). In the IR and PEP-IR groups, ventilation-perfusion was discontinued for about 60 min after a 30-min stable period and then restarted. The capillary filtration coefficients ( K) and pyruvate concentration in the perfusate were determined immediately before ischemia and 30 and 60 min after reperfusion. The left lungs were dried at the end of the experiment to calculate the tissue wet-to-dry weight ratio (W/D). The K values after reperfusion were significantly higher in the IR group than in the other two groups. Pyruvate concentrations were significantly higher at three time-points in the PEP-IR group than in the other two groups. The W/D was significantly higher in the IR group than in the other two groups. Based on these results, we conclude that the administration of PEP prior to lung ischemia alleviates lung ischemia-reperfusion injury. [ABSTRACT FROM AUTHOR]

An interview with respiratory physiologist John Burnard West, who is well known for his research on ventilation perfusion inequality, is presented. Topics include the influence of his parents's medical background in his career choice, his meeting with environmental physiologist Hermann Rahn, and work experiences at a medical school at the University of California in San Diego.

Background: Classifying the severity of bronchopulmonary dysplasia (BPD) by continuous numerical variables would facilitate follow-up of disease progression and quantified analysis of disease determinants. Objectives: To non-invasively measure oxygenation impairment in BPD by the degree of right-to-left shunt, right shift of the oxyhaemoglobin dissociation curve and ventilation/perfusion (VA/Q) inequality and to explore their relation with clinical parameters. Methods: Prospective cohort study of 24 infants with a median (interquartile range, IQR) gestation of 25 weeks (24-27) and a birth weight of 0.70 kg (0.63-0.93), studied at 36 days (30-66), at a postmenstrual age (PMA) of 33 weeks (29-36). Inspired oxygen (FIO2) was varied to obtain three to five transcutaneous oxygen saturation (SpO2) values between 85 and 96%. Values of shunt, shift and VA/Q were obtained by plotting the paired data of SpO2 against FIO2 for each infant using a unique program. Right-to-left shunt, right shift of the oxyhaemoglobin dissociation curve and VA/Q were measured in infants born <32 weeks PMA receiving oxygen at 28 days. Results: The median (IQR) shunt was 8% (0.3-16.5), shift 14.5 kPa (10.9-19.4) and VA/Q 0.40 (0.30-0.48). Shunt, shift and VA/Q were significantly related to gestational age (GA) at birth, PMA at study, weight at study and weight gain per week. Conclusions: Severity of pulmonary oxygenation impairment in BPD can be quantified at the cot-side by non-invasive measurement of shunt, shift and VA/Q. Low GA at birth, low weight at birth and at the time of study and impaired weight gain are significantly associated with the severity of oxygen-exchange impairment in infants with BPD. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Aim: The aim of the current study was to evaluate the relationship of intrapulmonary shunt with FiO2 alterations in patients treated with mechanical ventilation in intensive care unit for extrapulmonary disorders. Also, we aimed to assess the role of correlation between shunt ratio and PaO2/FiO2, PaO2/PAO2, P(A-a) O2 values in determining the treatment strategies. Methods: Twenty patients between ages of 19 and 75 years, requiring mechanical ventilation were enrolled into the study. We excluded two patients due to congestive heart failure and two patients due to acute respiratory distress syndrome (ARDS). Shunt fraction, P(A-a)O2, PaO2/FiO2, PaO2/PAO2 values were calculated at each FiO2 level for each patient. Results: The lowest median shunt value was measured at FiO2: 0.3 There was a significant correlation between shunt values at FiO2 0.5 and 0.7 (r=0.850). The highest mean value of P(A-a)O2 was measured at FiO2: 1 (382.91 ±106.46), and the lowest value of P(A-a)O2 was measured at FiO2: 0.21 (38.64±16.97). PaO2/FiO2 and PaO2/PAO2 ratios measured at FiO2: 0.3 and 0.5 were found to be statistically significant. Conclusion: In this study, we have shown increased shunt fraction at FiO2: 1 level. Different oxygenation indices and shunt measurements give us important and useful knowledge about the patients' current condition. [ABSTRACT FROM AUTHOR]

Respiratory sinus arrhythmia (RSA) is an acceleration of heart rate during inspiration and deceleration with expiration. We asked whether or not in humans some of the volume-related information necessary for RSA originated from the chest wall. Men and women, 19-20 years old, were breathing supine. Rib cage and abdomen displacement provided an index of tidal volume (VT) and RSA was computed breath-by-breath from the peak and trough of instantaneous heart rate. First, measurements were taken during breathing at rest (protocol a, 129 male and 164 female). Then, in subgroups of the original subject population, measurements were collected for the first five breaths immediately following a brief breath-hold period (protocol b), predominantly with the rib cage or predominantly with the abdomen (protocol c), above functional residual capacity or below it (protocol d). As long as VT was constant, severe chest wall distortion (protocol c) did not modify RSA. A drop in absolute lung volume (protocol d) oran increase in VT (protocol b) respectively decreased and increased RSA. The results, globally taken, are compatible with the notion that in humans changes in lung volume are detected by lung mechanoreceptors, whereas chest wall reflexes play no role in RSA. No difference in RSA emerged between genders during resting breathing or modest breath-hold hyperventilation. [ABSTRACT FROM AUTHOR]

The article presents a study comparing the cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine and spontaneously breathing 50 percent or maximal oxygen concentrations. Topics also discussed include the ventilation-perfusion ratio, the effect of absorption atelectasis due to absorption of alveolar gas, and the observbation of lithium dilution cardiac output.

The article presents a profile of respiratory physiologist, pulmonologist, researcher and professor John B. West. Topics discussed include West's participation in an expedition to the Himalayas in 1960 to study high-altitude physiology, his research about ventilation-perfusion ratio and regional differences in perfusion, ventilation and gas exchange, and his creation of the Department of Medicine's Division of Physiology in the School of Medicine at the University of California in San Diego.

Abstract: Invented and first approved for clinical use in Australia 36 years ago, Technegas is the technology that enabled ventilation scintigraphy with 99m Tc-labeled carbon nanoparticles ( 99m Tc-CNP). The US Food and Drug Administration (FDA) has considered this technology for more than 30 years but only now is getting close to approving it. Meanwhile, more than 4.4 million patients benefited from this technology in 64 countries worldwide. The primary application of 99m Tc-CNP ventilation imaging is the diagnostic evaluation for suspicion of pulmonary embolism using ventilation-perfusion quotient (V/Q) imaging. Because of 99m Tc-CNP's long pulmonary residence, tomographic imaging emerged as the preferred V/Q methodology. The FDA-approved ventilation imaging agents are primarily suitable for planar imaging, which is less sensitive. After the FDA approval of Technegas, the US practice will likely shift to tomographic V/Q. The 99m Tc-CNP use is of particular interest in the COVID-19 pandemic because it offers an option of a dry radioaerosol that takes approximately only 3 to 5 tidal breaths, allowing the shortest exposure to and contact with possibly infected patients. Indeed, countries where 99m Tc-CNP was approved for clinical use continued using it throughout the COVID-19 pandemic without known negative viral transmission consequences. Conversely, the ventilation imaging was halted in most US facilities from the beginning of the pandemic. This review is intended to familiarize the US clinical nuclear medicine community with the basic science of 99m Tc-CNP ventilation imaging and its clinical applications, including common artifacts and interpretation criteria for tomographic V/Q imaging for pulmonary embolism., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: A 67-year-old woman presented with shortness of breath and a ventilation/perfusion scan was performed. Initial images demonstrated mismatched bilateral apical defects that would be classified as high probability for pulmonary emboli. However, it was unusual that the defects were only in the bilateral apices. Investigation discovered that 99m Tc-MAA was administered while the patient was in a seated position. Repeat scan the following day with the patient in the correct, supine, position during 99m Tc-MAA administration demonstrated no defects. In this case, incorrect patient positioning could have resulted in an incorrect diagnosis of pulmonary emboli and inappropriate treatment of the patient., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: To identify adverse health effects due to air pollution derived from a cement plant in Korea. The ventilation impairment in residents around a cement plant was compared to another group through a pulmonary function test (PFT). Methods: From June to August of 2013, both a pre and post-bronchodilator PFT was conducted on a "more exposed group (MEG)" which consisted of 318 people who lived within a 1 km radius of a cement plant and a "less exposed group (LEG)" which consisted of 129 people who lived more than 5 km away from the same plant. The largest forced expiratory volume in a one second (FEV1) reading and a functional residual capacity (FVC) reading were recorded after examining the data from all of the usable curves that were agreed upon as valid by PFT experts of committee of National Institute of Environmental Research. The global initiative for chronic obstructive lung disease (GOLD) criteria for COPD, defined the FEV1/FVC ratio < 0.7 as the obstructive type, and the FEV1/FVC ratio ⩾ 0.7 and FVC% predicted < 80% were as the restrictive type. The FVC% predicted value was estimated using Korean equation. We compared the proportion of lung function impairments between the MEG and the LEG by using a chi-square, and estimated the OR of obstructive and restrictive ventilation impairments by logistic regression. Results: The obstructive type impairment proportion was 9.7% in the MEG, whereas it was 8.5% in the LEG. The restrictive type was 21.6% in the MEG which was more than the 12.4% of the LEG. The odds ratio (OR) of total ventilation impairment in the MEG was 2.63 (95% CI 1.50 ∼ 4.61) compared to the LEG. The OR of obstructive type in the MEG was 1.60 (95% CI 0.70 ∼ 3.65), the smoking history was 3.10 (CI 1.10 ∼ 8.66) whereas OR of restrictive type in the MEG was 2.55 (95% CI 1.37 ∼ 4.76), the smoking history was 0.75 (95% CI 0.35 ∼ 1.60) after adjusting for sex and age. Level of exposure to particulate played a role in both types. However, it appeared to be a significant variable in restrictive type, while smoking history was also an important variable in obstructive type. Conclusion: Although this study is a limited cross-section study with a small number of subjects, ventilation impairment rate is higher in the MEG. There might be a possibility that it is due to long-term exposure to particulate dust generated by the cement plant. [ABSTRACT FROM AUTHOR]

Oxygen capture in the lung results from the intimate dynamic interaction between the space- and time-dependent oxygen partial pressure that results from convection-diffusion and oxygen extraction from the alveolar gas and the space and time dependence of oxygen trapping by the red blood cells flowing in the capillaries. The complexity of the problem can, however, be reduced due to the fact that the systems obey different time scales: seconds for the gas phase transport and tenths of seconds for oxygen trapping by blood. This results first from a dynamical study of gas transport in a moving acinus and second from a new theory of dynamic oxygen trapping in the capillaries. The global solution can be found only through a self-consistent iterative approach linking the two systems. This has been accomplished and used to quantify oxygen capture in various situations: at rest, during exercise, ventilation–perfusion mismatching, high altitude and pulmonary edema. [ABSTRACT FROM AUTHOR]

Ventilator hyperinflations are used by physiotherapists for the purpose of airway clearance in intensive care. There is limited data to guide the selection of mechanical ventilator modes and settings that may achieve desired flow patterns for ventilator hyperinflation. A mechanical ventilator was connected to two lung simulators and a respiratory mechanics monitor . Peak inspiratory (PIFR) and expiratory flow rates (PEFR) were measured during manipulation of ventilator modes (pressure support ventilation [PSV], volume-controlled synchronised intermittent mandatory ventilation [VC-SIMV] and pressure-controlled synchronised intermittent mandatory ventilation [PC-SIMV]) and ventilator settings (including set tidal volume, positive end-expiratory pressure, inspiratory flow rate, inspiratory pause, pressure support, inspiratory time and/or inflation pressure). Additionally, each trial was conducted with high (0.05 l/cmH2O) and low (0.01 l/cmH2O) compliance settings on the lung simulators. Each trial was dichotomised into success or failure under three categories (attainment of PIFR/PEFR less than or equal to 0.9, PEFR-PIFR greater than 17 l/min, PEFR greater than or equal to 40 l/min). A total of 232 trials were conducted (96 VC-SIMV, 96 PC-SIMV, 40 PSV). A greater proportion of VC-SIMV trials were ceased due to high peak inspiratory pressures (35%). However, VC-SIMV trials were more likely to be successful at meeting all three outcome measures (26 VC-SIMV trials, 7 PC-SIMV trials, 0 PSV trials). It was found that manipulation of settings in VC-SIMV mode appears more successful than PSV and PC-SIMV for ventilator hyperinflations. [ABSTRACT FROM AUTHOR]

Background: Exercise-induced bronchoconstriction (EIB) describes the phenomenon of transient airway narrowing in association with physical activity. Although it may seem likely that EIB would have a detrimental impact on athletic performance, this has yet to be established. Objectives: The aim of this review is to provide a systematic appraisal of the current status of knowledge regarding EIB and exercise performance and to highlight potential mechanisms by which performance may be compromised by EIB. Data Sources and Study Selection: PubMed/Medline and EBSCO databases were searched up to May 2014 using the search parameter: [('exercise' OR 'athlete') AND ('asthma' OR 'bronchoconstriction' OR 'hypersensitivity') AND 'performance']. This search string returned 243 citations. After systematically reviewing all of the abstracts, 101 duplicate papers were removed, with 132 papers excluded for not including an exercise performance outcome measure. Results: The remaining ten studies that met the initial criteria were included in this review; six evaluated the performance of physically active individuals with asthma and/or EIB while four assessed the effects of medication on performance in a comparable population. Conclusion: The evidence concludes that whilst it is reasonable to suspect that EIB does impact athletic performance, there is currently insufficient evidence to provide a definitive answer. [ABSTRACT FROM AUTHOR]

We describe a three-compartment model (shunt and two perfused compartments) to analyse the relationship between inspired oxygen (FO) and arterial oxygen saturation (SO) in terms of pulmonary shunt and ventilation-perfusion ratio (V/Q). The program was tested using 24 exact datasets, each with six pairs of FO and SO data points with known V/Q and shunt, generated by a complex calculator of gas exchange. Additional datasets were created by adding noise and rounding the exact sets, and by reducing the number of data points per dataset. The importance of the oxyhaemoglobin dissociation curve and the arterio-venous difference in oxygen content (avDO) were also tested. Analysis using the three compartment model was more accurate than the two compartment model and less affected by data degradation. The absolute error in shunt estimation was never more than 2.2 % for the exact and rounded datasets, but the error in V/Q estimation was −29 to 19 % of the true value (10th-90th centiles). The characteristics of the well-ventilated compartment were not determined accurately. At extremes of cardiac output, an assumed value of avDO resulted in significant errors. It is probably advantageous to correct for foetal haemoglobin in neonatal datasets. Analysis of FO versus SO datasets using a three compartment model provides accurate estimates of shunt and V/Q when arterio-venous difference in oxygen content is known. The estimates may have value as objective measures of gas exchange, and as a visual guide for oxygen therapy. [ABSTRACT FROM AUTHOR]

The field of proton lung MRI is advancing on a variety of fronts. In the realm of functional imaging, it is now possible to use arterial spin labeling (ASL) and oxygen-enhanced imaging techniques to quantify regional perfusion and ventilation, respectively, in standard units of measurement. By combining these techniques into a single scan, it is also possible to quantify the local ventilation-perfusion ratio, which is the most important determinant of gas-exchange efficiency in the lung. To demonstrate potential for accurate and meaningful measurements of lung function, this technique was used to study gravitational gradients of ventilation, perfusion, and ventilation-perfusion ratio in healthy subjects, yielding quantitative results consistent with expected regional variations. Such techniques can also be applied in the time domain, providing new tools for studying temporal dynamics of lung function. Temporal ASL measurements showed increased spatial-temporal heterogeneity of pulmonary blood flow in healthy subjects exposed to hypoxia, suggesting sensitivity to active control mechanisms such as hypoxic pulmonary vasoconstriction, and illustrating that to fully examine the factors that govern lung function it is necessary to consider temporal as well as spatial variability. Further development to increase spatial coverage and improve robustness would enhance the clinical applicability of these new functional imaging tools. In the realm of structural imaging, pulse sequence techniques such as ultrashort echo-time radial k-space acquisition, ultrafast steady-state free precession, and imaging-based diaphragm triggering can be combined to overcome the significant challenges associated with proton MRI in the lung, enabling high-quality three-dimensional imaging of the whole lung in a clinically reasonable scan time. Images of healthy and cystic fibrosis subjects using these techniques demonstrate substantial promise for non-contrast pulmonary angiography and detailed depiction of airway disease. Although there is opportunity for further optimization, such approaches to structural lung imaging are ready for clinical testing. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Objectives To determine whether the Wells clinical prediction rule for pulmonary embolism ( PE), which produces a point score based on clinical features and the likelihood of diagnoses other than PE, combined with normal D-dimer testing can be used to exclude PE in older unhospitalized adults. Design Prospective cohort study. Setting Primary care and nursing homes. Participants Older adults (≥60) clinically suspected of having a PE (N = 294, mean age 76, 44% residing in a nursing home). Measurements The presence of PE was confirmed using a composite reference standard including computed tomography and 3-month follow-up. The proportion of individuals with an unlikely risk of PE was calculated according to the Wells rule (≤4 points) plus a normal qualitative point-of-care D-dimer test (efficiency) and the presence of symptomatic PE during 3 months of follow-up within these patients (failure rate). Results Pulmonary embolism occurred in 83 participants (28%). Eighty-five participants had an unlikely risk according to the Wells rule and a normal D-dimer test (efficiency 29%), five of whom experienced a nonfatal PE during 3 months of follow-up (failure rate = 5.9%, 95% confidence interval ( CI) = 2.5-13%). According to a refitted diagnostic strategy for older adults, 69 had a low risk of PE (24%), two of whom had PE (failure rate = 2.9%, 95% CI = 0.8-10%). Conclusion The use of the well-known and widely used Wells rule (original or refitted) does not guarantee safe exclusion of PE in older unhospitalized adults with suspected PE. This may lead to discussion among professionals as to whether the original or revised Wells rule is useful for elderly outpatients. [ABSTRACT FROM AUTHOR]

This paper presents a model of alveolar-capillary oxygen diffusion with dynamics of air transport through the respiratory tract. For this purpose electrical model representing the respiratory tract mechanics and differential equations representing oxygen membrane diffusion are combined. Relevant thermodynamic relations describing the mass of oxygen transported into the human body are proposed as the connection between these models, as well as the influence of ventilation-perfusion mismatch on the oxygen diffusion. The model is verified based on simulation results of varying exercise intensities and statistical calculations of the results obtained during various clinical trials. The benefit of the approach proposed is its application in simulation-based research aimed to generate quantitative data of normal and pathological conditions. Based on the model presented, taking into account many essential physiological processes and air transport dynamics, comprehensive and combined studies of the respiratory efficiency can be performed. The impact of physical exercise, precise changes in respiratory tract mechanics and alterations in breathing pattern can be analyzed together with the impact of various changes in alveolar-capillary oxygen diffusion. This may be useful in simulation of effects of many severe medical conditions and increased activity level. [ABSTRACT FROM AUTHOR]

The article presents information on the reliability of on-call radiology residents' interpretation of 64-slice computed tomography (CT) pulmonary angiography for the detection of pulmonary embolism (PE). Topics discussed include evaluation of PE using a combination of ventilation-perfusion (V/Q) lung scanning and conventional pulmonary angiography.