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Objectives: With increased bicycle use during the COVID-19 pandemic and growing availability of bicycle-sharing programs in Montreal, we hypothesize helmet use has decreased. The aim of this study was to evaluate helmet use and proper fit among Montreal cyclists during the pandemic relative to historical data., Methods: Nine observers collected data on bike type, gender, helmet use, and ethnicity using the iHelmet© app at 18 locations across the island of Montreal from June to September 2021. Proper helmet wear was assessed at one busy location. Multiple logistic regression was used to identify factors associated with helmet wear and results were compared to a historical study., Results: Of the 2200 cyclists observed, 1109 (50.4%) wore a helmet. Males (OR = 0.78, 95%CI = 0.65-0.95), young adults (OR = 0.65, 95%CI = 0.51-0.84), visible minorities (OR = 0.38, 95%CI = 0.28-0.53), and bike-share users (OR = 0.21, 95%CI = 0.15-0.28) were less likely to be wearing a helmet, whereas children (OR = 3.92, 95%CI = 2.17-7.08) and cyclists using racing bicycles (OR = 3.84, 95%CI = 2.62-5.62) were more likely to be wearing a helmet. The majority (139/213; 65.3%) of assessed cyclists wore properly fitting helmets. Children had the lowest odds of having a properly fitted helmet (OR = 0.13, 95%CI = 0.04-0.41). Compared to 2011, helmet use during the pandemic increased significantly (1109/2200 (50.4%) vs. 2192/4789 (45.8%); p = 0.032)., Conclusion: Helmet use among Montreal cyclists was associated with age, gender, ethnicity, and type of bicycle. Children were least likely to have a properly fitted helmet. The recent increase in popularity of cycling and expansion of bicycle-sharing programs reinforce the need for bicycle helmet awareness initiatives, legislation, and funding prioritization., (© 2023. The Author(s) under exclusive license to The Canadian Public Health Association.)

Purpose: We assessed the immunogenicity and safety of the BNT162b2 vaccine in a large cohort of patients with cancer (CP)., Experimental Design: From March 1, 2021 to March 20, 2021, this prospective cohort study included 816 CP afferent to our institution and eligible for the vaccination. A cohort of 274 health care workers (HCW) was used as age- and sex-matched control group. BNT162b2 was administered as a two-dose regimen given 21 days apart. Blood samples to analyze anti-Spike (S) IgG antibodies (Ab) were collected prevaccination [timepoint (TP) 0], and at 3 weeks (TP1) and 7 weeks (TP2) after the first dose., Results: Patients characteristics: median age 62 (range, 21-97); breast/lung cancer/others (31/21/48%); active treatment/follow-up (90/10%). In the whole CP cohort, the serologic response rate (RR) and the titre of anti-S IgG significantly increased across the TPs; at TP2, the responders (IgG >15 AU/mL) were 94.2%. Active chemotherapy and chronic use of steroids were independent predictors of lower RR. Adverse events (AE) after the booster predicted higher likelihood of response (OR, 4.04; 95% confidence interval, 1.63-9.99; P = 0.003). Comparing the matched cohorts, the responders were significantly lower in CP than in HCW at TP1 (61.2% vs. 93.2%) and TP2 (93.3% vs. 100%), while the geometric mean concentration of IgG did not significantly differ at TP2 being significantly lower in CP (23.3) than in HCW (52.1) at TP1. BNT162b2 was well tolerated in CP; severe-grade AEs were 3.5% and 1.3% after the first and second doses, respectively., Conclusions: BNT162b2 assures serologic immunization without clinically significant toxicity in CP. The second dose is needed to reach a satisfactory humoral response., (©2021 American Association for Cancer Research.)

Summary: The use of resuscitative endovascular balloon occlusion of the aorta (REBOA) in penetrating injuries is an emerging adjunct in the civilian trauma surgeon’s toolbox for the management of traumatic hemorrhagic shock. Furthermore, within the Canadian civilian context, little has been reported with regard to its use as an assisted damage-control measure in vascular reconstruction of the lower extremity. We report a case of penetrating gunshot injury of the lower extremity where the preoperative deployment of REBOA had a remarkable positive impact in the resuscitation phase and the intraoperative control of blood loss. A description of the procedure and the advantage gained from REBOA are discussed., Competing Interests: D. Deckelbaum and A. Beckett are CJS associate editors. They were not involved in the review of this manuscript or in the decision to accept it for publication. No other competing interests declared., (© 2019 Joule Inc. or its licensors)

Background: The effect of labor epidural analgesia (LEA) on successful breastfeeding has been evaluated in several studies with divergent results. We hypothesized that LEA would not influence breastfeeding status 6 weeks postpartum in women who intended to breastfeed in an environment that encourages breastfeeding., Methods: In this prospective observational cohort study, a total of 1204 women intending to breastfeed, delivering vaginally with or without LEA, were included; breastfeeding was recorded at 3 days and 6 weeks postpartum. Primary outcome was breastfeeding at 6 weeks, and the χ test was used for comparisons between women delivering with and without LEA, according to parity status and previous breastfeeding experience. Total epidural fentanyl dose and oxytocin use (yes/no) were recorded. A multivariable logistic regression was performed to assess factors affecting breastfeeding at 6 weeks., Results: The overall breastfeeding rate at 6 weeks was 76.9%; it was significantly lower among women delivering with LEA (74.0%) compared with women delivering without LEA (83.4%; P < .001). Among 398 nulliparous women, 84.9% delivered with LEA, compared with 61.8% of multiparous women (P < .001). Multiparous women (N = 806) were more likely to breastfeed at 6 weeks (80.0% vs 70.6% nullipara; P < .001). Using multivariable logistic regression that accounted for 14 covariates including parity, and an interaction term between parity and LEA use, LEA was significantly associated with reduced breastfeeding at 6 weeks (odds ratio, 0.60; 95% confidence interval, 0.40-0.90; P = .015). In a modified multivariable logistic regression where parity was replaced with previous breastfeeding experience, both as a covariate and in the interaction term, only previous breastfeeding experience was associated with increased breastfeeding at 6 weeks (odds ratio, 3.17; 95% confidence interval, 1.72-5.80; P < .001)., Conclusions: In our mixed-parity cohort, delivering with LEA was associated with reduced likelihood of breastfeeding at 6 weeks. However, integrating women's previous breastfeeding experience, the breastfeeding rate was not different between women delivering with and without LEA among the subset of multiparous women with previous breastfeeding experience. Therefore, our findings suggest that offering lactation support to the subset of women with no previous breastfeeding experience may be a simple approach to improve breastfeeding success. This concept subscribes to the notion that women at risk for an undesired outcome be offered tailored interventions with a personalized approach.

Summary: Noncompressible hemorrhagic control remains one of the most challenging areas in damage control medicine and continues to be a leading cause of preventable death. For decades, emergency thoracotomy or laparotomy and aortic cross clamping have remained the gold standard intervention. Recently, there has been a movement toward less invasive techniques for noncompressible hemorrhagic control, such as resuscitative endovascular balloon occlusion of the aorta (REBOA). The REBOA technique involves inflation of an endovascular balloon within the abdominal aorta proximal to the vascular injury to temporarily inhibit bleeding. Although the literature is robust on this new technique, skepticism remains about whether REBOA is superior to aortic cross clamping, as it has been associated with complications including organ and limb ischemia, limb amputation, femoral aneurysm, and thrombosis., Competing Interests: None declared., (© 2019 Joule Inc. or its licensors)

Background: Postpartum depression (PPD) is associated with pain during and after delivery, with studies showing reduced rates among women delivering with labor epidural analgesia (LEA). We hypothesized that women who intend to deliver with LEA but do not receive it are at higher risk for PPD at 6 weeks due to the combined experience of untreated labor pain and unmatched expectations during labor, and evaluated the interaction between labor plans related to LEA, satisfaction with pain control when actually delivering with LEA, and PPD at 6 weeks after delivery., Methods: A total of 1497 women with a vaginal delivery were enrolled into this prospective longitudinal study. Women's initial intention to deliver with or without LEA, how they subsequently delivered, and satisfaction with pain relief were recorded on postpartum day 1. Primary aim was selected as PPD at 6 weeks among women intending to deliver with but subsequently delivering without LEA compared with the rest of the cohort. Primary outcome was PPD at 6 weeks using the Edinburgh Postnatal Depression Scale; PPD was defined with a score ≥10 (scale from 0 to 30). Demographic and obstetric data were recorded. Fisher exact test was used for comparisons between groups. The interaction between intention and actual delivery with regard to LEA and PPD was tested., Results: Overall, 87 of 1326 women completing the study at 6 weeks had PPD (6.6%). For the primary aim, 439 (29.3%) delivered without LEA, of which 193 (12.9%) had intended to deliver with LEA; the PPD rate among these women was 8.1%, which was not statistically different from the rest of the cohort (6.3%; odds ratio [OR], 1.30; 95% confidence interval [CI], 0.72-2.38; P = .41). A total of 1058 women (70.7%) delivered with LEA and 439 (29.3%) delivered without; therefore, 1169 (78.1%) delivered as intended and 328 (21.9%) did not (unmatched expectations). Evaluating the interaction between effects, there was a strong negative additive interaction between intending to deliver without LEA and actually delivering with LEA (risk difference = -8.6%, 95% CI, 16.2%-1.6%; P = .014) suggesting that unmatched intention effect is significantly associated with negative outcome. In multiple regression analysis, while intending to deliver with LEA (OR, 1.06; 95% CI, 1.01-1.11; P = .029) and actually delivering with LEA (OR, 1.07; 95% CI, 1.01-1.13; P = .018) both increased the odds for PPD, the multiplicative interaction was protective (OR, 0.92; 95% CI, 0.86-0.99; P = .022), after adjusting for cofactors., Conclusions: Our study results did not demonstrate a significant increase in the odds for PPD at 6 weeks among women who intended to deliver with LEA but subsequently delivered without. However, we identified a protective interaction between intended LEA use and actual use on the incidence of PPD. Our data suggest an increased risk when women do not deliver as intended, particularly when not initially intending to deliver with LEA. The relationship between unplanned LEA and PPD may be mediated by a physically difficult delivery rather than or in addition to negative emotions related to unmet expectations or a sense of personal failure; therefore, counseling women after delivery to address any negative perceptions may be useful.

Background: Ralstonia spp , an environmental microorganism, has been occasionally associated with healthcare infections. The aim of this study was to investigate an outbreak caused by Ralstonia mannitolilytica in oncology patients., Methods: Case definition: Oncology outpatients attending a day ward, with positive blood and/or central venous catheter (CVC) culture for Ralstonia spp from September 2013 - June 2014. We analysed medical records, procedures and environmental samples. R. mannitolilytica was identified by 16S rRNA sequencing, and typed by Pulsed Field Gel Electrophoresis (PFGE); resistance to carbapenemes was investigated by phenotypic and molecular methods., Results: The patients ( N  = 22) had different malignancies and received different therapy; all had a CVC and 16 patients presented chills and/or fever. R. mannitolilytica was isolated from both blood and CVC ( n  = 12) or only blood ( n  = 6) or CVC tips ( n  = 4). The isolates had indistinguishable PFGE profile, and showed resistance to carbapenems. All the isolates were negative for carbapenemase genes while phenotypic tests suggests the presence of an AmpC β-lactamase activity,responsible for carbapenem resistance. All patients had had CVC flushed with saline to keep the venous access pervious or before receiving chemotherapy at various times before the onset of symptoms. After the first four cases occurred, the multi-dose saline bottles used for CVC flushing were replaced with single-dose vials; environmental samples were negative for R. mannitolilytica., Conclusions: Although the source of R. mannitolilytica remains unidentified, CVC flushing with contaminated saline solution seems to be the most likely origin of R. mannitolilytica CVC colonization and subsequent infections. In order to prevent similar outbreaks we recommend removal of any CVC that is no longer necessary and the use of single-dose solutions for any parenteral treatment of oncology patients.

Background: Unintended dural puncture (UDP) is one of the main risks of epidural analgesia, with a reported incidence of approximately 1.5% among the obstetric population. UDP is associated with maternal adverse outcomes, with the most frequent adverse outcome being postdural puncture headache (PDPH). Our retrospective cohort study objective was to identify demographic and obstetric risk factors that increase the risk of unintentional dural puncture as well as describing the obstetric outcome once a dural puncture has occurred., Methods: We retrospectively reviewed all cases of UDPs during attempted vaginal delivery between the years 2004 and 2013 in a single Israeli hospital. Each UDP case was matched with the 2 parturients who received epidural analgesia before and 2 parturients after performed by the same anesthesiologist (control group). Demographic, anesthetic, and obstetric variables were compared between the UDP and control groups., Results: Out of 46,668 epidural procedures, 177 cases of UDPs were documented (0.4%). One hundred seven women (60.5%) developed PDPH, and 38 (35.5%) required an epidural blood patch. In multivariate logistic regression, the degree of cervical dilation in centimeters at the time of epidural insertion was associated with an increased rate of UDP (P < .001). Multiparity was associated with PDPH after UDP (P = .004). Women with UDP had longer length of hospital stay than those without UDP (P < .001)., Conclusions: UDP, an uncommon complication, is associated with obstetric factors. Nevertheless, it does not seem to be associated with adverse obstetric outcomes except for prolonged duration of hospital stay.

Volatile anesthetic agents have been used for decades in the peri-operative setting. Data from the past 15 years have shown that pre-injury administration of volatile anesthetic can decrease the impact of ischemia-reperfusion injury on the heart, brain, and kidney. Recent data demonstrated that volatile agents administered shortly after injury can decrease the ischemia-reperfusion injury. Several questions need to be answered to optimize this therapeutic target, but this is a promising era of secondary injury mitigation.

Background: Regional cerebral oxygen saturation (S(ct)O(2)) has recently been shown to decrease significantly during thoracic surgery. The present study investigates whether these desaturations are related to postoperative complications., Methods: Fifty patients undergoing thoracic surgery with a single-lung ventilation (SLV) of >45 min duration were enrolled. Regional cerebral oxygen saturation was measured using absolute oximetry; standard clinical variables, and SOFA and Clavien scores were recorded. Correlation between minimum S(ct)O(2) during SLV and postoperative complication scores was analysed using Pearson's correlation test, chi(2) test, and logistic regression., Results: Forty-seven patients underwent lobectomy, two patients a pneumonectomy and 1 patient a chest wall resection. Eighty-two per cent of the patients had a decrease in S(ct)O(2) of >15% from baseline value, and 10% of the patients had a minimal absolute S(ct)O(2) value between 45% and 55%. The minimal absolute S(ct)O(2) values during SLV correlated with the Clavien score (R(2)=0.098, P=0.0201) and the non-respiratory SOFA score (R(2)=0.090, P=0.0287). By defining a threshold of S(ct)O(2)=65%, the odds ratio of having a non-respiratory organ failure was 2.37 (95% CI 1.18-4.39, P=0.043) and a complication according to the Clavien score (Clavien score >0) was 3.19 (95% CI 1.60-6.34, P=0.0272)., Conclusions: Thoracic surgery with SLV seemed to be associated with a significant decrease in S(ct)O(2), and minimal S(ct)O(2) values correlated positively with postoperative complications.

Background: A novel monitoring system (integrated monitor of anaesthesia, IMA) which integrates three components of general anaesthesia on one single display was developed. The focus of this study was to evaluate the performance and user-friendliness of four different display designs., Methods: Four interface displays of the IMA were developed, including one numerical, one numerical and graphical (mixed numerical-graphical), one only graphical, and one an advanced two-dimensional graphical display. Each of the four displays was evaluated in a random order by 10 staff anaesthetists and 10 residents/fellows using a set of five scenarios. Scenarios involved one or more abnormal variables that participants had to verbally phrase. For each interface test, reaction time, response accuracy, and NASA-Task Load Index were measured and compared., Results: The numerical, graphical, and advanced-graphical interfaces yielded similar median reaction times, respectively, 7.99 s (5.15-10.79), 8.21 s (6.20-11.88), and 9.43 s (6.19-13.3). Reaction times were significantly shorter (P<0.006) with the mixed numerical-graphical interface: 6.26 s (4.52-8.32). The correct response rate was significantly lower in the graphical interface. The three others presented no statistical difference when compared among each other. The mixed numerical-graphical interface yielded a significantly lower NASA-TLX than the numerical and the advanced-graphical interfaces (19/100 vs 34/100, P<0.003)., Conclusions: A mixed numerical-graphical display design appears to present the best results in terms of user reaction times, response accuracy, and performance index when detecting abnormal critical events.

Background: Single-lung ventilation (SLV) during thoracic surgery causes important cardiopulmonary disturbances. Absolute cerebral oximetry was used to determine the incidence and magnitude of the decrease in cerebral oxygen saturation (Sct(o(2))) in patients undergoing SLV during thoracic surgery., Methods: Data were obtained from 20 consecutive patients undergoing thoracic surgery and necessitating SLV of more than 1 h. The FORESIGHTtrade mark (CASMED, USA) absolute oximeter was used to measure left, right, and average absolute Sct(o(2)) every 5 min from the awake state to extubation. Bispectral index and standard monitoring parameters were also recorded every 5 min. Blood gas analysis was performed every 15 min. Data median (IQR) (range) were analysed using repeated-measures anova and Spearman's correlation test, P<0.05., Results: Patients [median age 65 yr (range 46-75)] showed an absolute Sct(o(2)) of 80% (78, 82) (74-87) in the awake state, which decreased to a minimum Sct(o(2)) value of 63% (57, 65) (53-73) during SLV to recover to an Sct(o(2)) of 71% immediately after extubation. During SLV, all patients had a decrease of more than 15% of the initial Sct(o(2)) and 70% of patients had a decrease of more than 20%. The decrease in Sct(o(2)) was not correlated with any standard clinical parameters, for example, arterial pressure, blood loss, peripheral oxygen saturation, or Pa(o(2))., Conclusions: Thoracic surgery with SLV seems to be associated with a significant decrease of Sct(o(2)) in the majority of patients. Parameters such as peripheral oxygen saturation or Po(2) which are used to guide SLV during thoracic surgery are not sufficient to detect significant cerebral oxygen desaturations.

Background: Percutaneous catheterization is a frequently-used technique to gain access to the central venous circulation. Inadvertent arterial puncture is often without consequence, but can lead to devastating complications if it goes unrecognized and a large-bore dilator or catheter is inserted. The present study reviews our experience with these complications and the literature to determine the safest way to manage catheter-related cervicothoracic arterial injury (CRCAI)., Methods: We retrospectively identified all cases of iatrogenic carotid or subclavian injury following central venous catheterization at three large institutions in Montreal. We reviewed the French and English literature published from 1980 to 2006, in PubMed, and selected studies with the following criteria: arterial misplacement of a large-caliber cannula (>/=7F), adult patients (>18 years old), description of the method for managing arterial trauma, reference population (denominator) to estimate the success rate of the therapeutic option chosen. A consensus panel of vascular surgeons, anesthetists and intensivists reviewed this information and proposed a treatment algorithm., Results: Thirteen patients were treated for CRCAI in participating institutions. Five of them underwent immediate catheter removal and compression, and all had severe complications resulting in major stroke and death in one patient, with the other four undergoing further intervention for a false aneurysm or massive bleeding. The remaining eight patients were treated by immediate open repair (six) or through an endovascular approach (two) for subclavian artery trauma without complications. Five articles met all our inclusion criteria, for a total of 30 patients with iatrogenic arterial cannulation: 17 were treated by immediate catheter removal and direct external pressure; eight (47%) had major complications requiring further interventions; and two died. The remaining 13 patients submitted to immediate surgical exploration, catheter removal and artery repair under direct vision, without any complications (47% vs 0%, P = .004)., Conclusion: During central venous placement, prevention of arterial puncture and cannulation is essential to minimize serious sequelae. If arterial trauma with a large-caliber catheter occurs, prompt surgical or endovascular treatment seems to be the safest approach. The pull/pressure technique is associated with a significant risk of hematoma, airway obstruction, stroke, and false aneurysm. Endovascular treatment appears to be safe for the management of arterial injuries that are difficult to expose surgically, such as those below or behind the clavicle. After arterial repair, prompt neurological evaluation should be performed, even if it requires postponing elective intervention. Imaging is suggested to exclude arterial complications, especially if arterial trauma site was not examined and repaired.

There have been great advancements in cardiac surgery over the last two decades; the widespread use of off-pump aortocoronary bypass surgery, minimally invasive cardiac surgery, and robotic surgery have also changed the face of cardiac anaesthesia. The concept of "Fast-track anaesthesia" demands the use of nondepolarising neuromuscular blocking drugs with short duration of action, combining the ability to provide (if necessary) sufficiently profound neuromuscular blockade during surgery and immediate re-establishment of normal neuromuscular transmission at the end of surgery. Postoperative residual muscle paralysis is one of the major hurdles for immediate or early extubation after cardiac surgery. Nondepolarising neuromuscular blocking drugs for cardiac surgery should therefore be easy to titrate, of rapid onset and short duration of action with a pathway of elimination independent from hepatic or renal dysfunction, and should equally not affect haemodynamic stability. The difference between repetitive bolus application and continuous infusion is outlined in this review, with the pharmacodynamic and pharmacokinetic characteristics of vecuronium, pancuronium, rocuronium, and cisatracurium. Kinemyography and acceleromyography are the most important currently used neuromuscular monitoring methods. Whereas monitoring at the adductor pollicis muscle is appropriate at the end of surgery, monitoring of the corrugator supercilii muscle better reflects neuromuscular blockade at more central, profound muscles, such as the diaphragm, larynx, or thoraco-abdominal muscles. In conclusion, cisatracurium or rocuronium is recommended for neuromuscular blockade in modern cardiac surgery.

Background: We present a 15-patient series of awake 'off-pump' [without cardiopulmonary bypass (CPB)] coronary artery bypass graft surgery, facilitated by thoracic epidural analgesia (TEA) and femoral nerve block., Methods: Surgery was performed with a conventional median sternotomy. Analgesia was provided with TEA at T1-2 or 2-3 interspace, using bupivacaine 0.5% and sufentanil 1.66 microg ml(-1), initially at 20 ml litre(-1) until T1-10 dermatomal block was achieved, then maintained at 2-14 ml litre(-1) throughout surgery. Femoral nerve block was performed before operation with neuro-stimulation at the saphenous vein harvest site with 10 ml each of bupivacaine 0.25% and lidocaine 2%. Successful awake surgery, avoiding general anaesthesia (GA) with adequate surgical conditions, without CPB was the primary end point., Results: Fifteen men, mean (sd) age of 63 (9) yr (range 49-81 yr), weight 78 (10) kg, underwent surgery. Three patients (20%) needed conversion to GA: one patient due to insufficient thoracic analgesia, another required initiation of CPB, and the third needed stabilization of the heart for graft suturing due to profound respiratory movements. All three were successfully extubated immediately after surgery. Awake surgery was successful and uneventful in 80% of cases., Conclusions: Combined TEA and femoral block is a novel anaesthetic technique, and is feasible, for cardiac surgery. However, certain technical limitations need to be overcome to evaluate the full potential of 'awake' cardiac surgery.

We present a case in which use of the Bonfils retromolar intubation fiberscope resulted in cervical and facial subcutaneous emphysema. The patient was a 75-yr-old woman with Mallampati Grade I airway. The Bonfils retromolar intubation fiberscope was used for teaching purposes. Flow on the oxygen port of the fiberscope was set at 10 L/min. Immediately after insertion of the scope, her whole face and cervical skin showed severe subcutaneous emphysema. The patient was intubated conventionally and the emphysema resolved within 24 h. Subcutaneous emphysema after air insufflation is known from dental procedures with air entering through holes in the teeth. In our case, the oxygen insufflation was sufficient to create emphysema, probably through tiny mucosal lesions.

The present study assessed the relative contribution of each body segment to whole body fat-free mass (FFM) and impedance and explored the use of segmental bioelectrical impedance analysis to estimate segmental tissue composition. Multiple frequencies of whole body and segmental impedances were measured in 51 normal and overweight women. Segmental tissue composition was independently assessed by dual-energy X-ray absorptiometry. The sum of the segmental impedance values corresponded to the whole body value (100.5 +/- 1.9% at 50 kHz). The arms and legs contributed to 47.6 and 43.0%, respectively, of whole body impedance at 50 kHz, whereas they represented only 10.6 and 34.8% of total FFM, as determined by dual-energy X-ray absorptiometry. The trunk averaged 10.0% of total impedance but represented 48.2% of FFM. For each segment, there was an excellent correlation between the specific impedance index (length2/impedance) and FFM (r = 0.55, 0.62, and 0.64 for arm, trunk, and leg, respectively). The specific resistivity was in a similar range for the limbs (159 +/- 23 cm for the arm and 193 +/- 39 cm for the leg at 50 kHz) but was higher for the trunk (457 +/- 71 cm). This study shows the potential interest of segmental body composition by bioelectrical impedance analysis and provides specific segmental body composition equations for use in normal and overweight women.

The present study was designed to explore the thermogenic effect of thyroid hormone administration and the resulting changes in nitrogen homeostasis. Normal male volunteers (n = 7) received thyroxin during 6 weeks. The first 3-week period served to suppress endogenous thyroid secretion (180 micrograms T4/day). This dose was doubled for the next 3 weeks. Sleeping energy expenditure (respiratory chamber) and BMR (hood) were measured by indirect calorimetry, under standardized conditions. Sleeping heart rate was continuously recorded and urine was collected during this 12-hour period to assess nitrogen excretion. The changes in energy expenditure, heart rate and nitrogen balance were then related to the excess thyroxin administered. After 3 weeks of treatment, serum TSH level fell to 0.15 mU/L, indicating an almost complete inhibition of the pituitary-thyroid axis. During this phase of treatment there was an increase in sleeping EE and sleeping heart rate, which increased further by doubling the T4 dose (delta EE: +8.5 +/- 2.3%, delta heart rate +16.1 +/- 2.2%). The T4 dose, which is currently used as a substitutive dose, lead to a borderline hyperthyroid state, with an increase in EE and heart rate. Exogenous T4 administration provoked a significant increase in urinary nitrogen excretion averaging 40%. It is concluded that T4 provokes an important stimulation of EE, which is mostly mediated by an excess protein oxidation.

Elective treatment of descending thoracic aneurysms involves direct surgery, with Dacron graft replacement of the diseased aortic segment. When the patient's condition contraindicates major surgery, however, the surgeon should consider using an extraanatomic approach-implanting an ascending aorta-to-abdominal aorta Dacron bypass graft in a ventral position and leaving the diseased segment undisturbed. After such a procedure, the descending thoracic aorta must be excluded from the normal circulation. For this purpose, we have designed an intraaortic occluding technique in which an umbrella-like device is implanted immediately distal to the left subclavian artery. This technique has proved safe and uncomplicated in canine experiments and is ready for clinical trials.

Between May 1976 and April 1977, 100 patients underwent cardiac valve replacement with a unique low profile glutaraldehyde-treated porcine aortic xenograft. These patients were classified in four groups: Group I, 43 patients who underwent isolated mitral valve replacement (MVR); Group II, 27 patients who had isolated aortic valve replacement (AVR); Group III, 10 patients who had MVR and AVR; and Group IV, 20 patients who had MVR or AVR associated with other cardiac procedures. The operative mortality for Group I was 2.3% (1 of 43) and 15% (3 of 20) in Group IV. The total operative mortality was 4% (4 of 100) and the late mortality was 1.02% (1 of 96 survivors), who died apparently secondary to a cardiac arrhythmia. During a follow-up period extending for 16 months, thromboembolic complications occurred early in the postoperative period in 3% (3 of 100), one patient with neurological residual, and two patients with transient symptoms only. The embolic complications occurred only in Group I. Considering all patients in whom the mitral valves were replaced, the incidence of emboli was 4.9% (3 of 61). The 96 patients did not receive anticoagulant therapy. Reoperation was necessary in one patient because of periprosthetic leak. The incidence of endocarditis was 1.02% (1 of 96 survivors). We recommend anticoagulant therapy for eight to twelve weeks postoperatively in MVR patients after bioprosthetic insertion.

The technique described here permits insertion of a large prosthesis into a small aortic annulus and avoids the necessity of additional procedures for enlarging the aortic ring. Inspection of the fibrous skeleton of the heart reveals that the large intervalvular trigone and the noncoronary sinus of Valsalva are remarkably elastic. Full advantage of this natural elasticity is achieved by suturing the prosthesis to the base of these structures from outside the aorta. Sutures are placed in the sinuses of the right and left cusps in the usual manner. Judicious application of this procedure allows the implantation of a No. 23 or No. 24 prosthesis in cases that would require a No. 19 or No. 21 with the use of conventional methods.