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Background: Cerebral oxygen desaturation during cardiac surgery has been associated with adverse perioperative outcomes. Before a large multicenter randomized controlled trial (RCT) on the impact of preventing desaturations on perioperative outcomes, the authors undertook a randomized prospective, parallel-arm, multicenter feasibility RCT to determine whether an intervention algorithm could prevent desaturations., Methods: Eight Canadian sites randomized 201 patients between April 2012 and October 2013. The primary outcome was the success rate of reversing cerebral desaturations below 10% relative to baseline in the intervention group. Anesthesiologists were blinded to the cerebral saturation values in the control group. Intensive care unit personnel were blinded to cerebral saturation values for both groups. Secondary outcomes included the area under the curve of cerebral desaturation load, enrolment rates, and a 30-day follow-up for adverse events., Results: Cerebral desaturations occurred in 71 (70%) of the 102 intervention group patients and 56 (57%) of the 99 control group patients (P = 0.04). Reversal was successful in 69 (97%) of the intervention group patients. The mean cerebral desaturation load (SD) in the operating room was smaller for intervention group patients compared with control group patients (104 [217] %.min vs. 398 [869] %.min, mean difference, -294; 95% CI, -562 to -26; P = 0.03). This was also true in the intensive care unit (P = 0.02). There were no differences in adverse events between the groups., Conclusions: Study sites were successful in reversal of desaturation, patient recruitment, randomization, and follow-up in cardiac surgery, supporting the feasibility of conducting a large multicenter RCT.

Background: Postoperative residual neuromuscular blockade (NMB), defined as a train-of-four (TOF) ratio of <0.9, is an established risk factor for critical postoperative respiratory events and increased morbidity. At present, little is known about the occurrence of residual NMB in Canada. The RECITE (Residual Curarization and its Incidence at Tracheal Extubation) study was a prospective observational study at 8 hospitals in Canada investigating the incidence and severity of residual NMB., Methods: Adult patients undergoing open or laparoscopic abdominal surgery expected to last <4 hours, ASA physical status I-III, and scheduled for general anesthesia with at least 1 dose of a nondepolarizing neuromuscular blocking agent for endotracheal intubation or maintenance of neuromuscular relaxation were enrolled in the study. Neuromuscular function was assessed using acceleromyography with the TOF-Watch SX. All reported TOF ratios were normalized to the baseline values. The attending anesthesiologist and all other observers were blinded to the TOF ratio (T4/T1) results. The primary and secondary objectives were to determine the incidence and severity of residual NMB (TOF ratio <0.9) just before tracheal extubation and at arrival at the postanesthesia care unit (PACU)., Results: Three hundred and two participants were enrolled. Data were available for 241 patients at tracheal extubation and for 207 patients at PACU arrival. Rocuronium was the NMB agent used in 99% of cases. Neostigmine was used for reversal of NMB in 73.9% and 72.0% of patients with TE and PACU data, respectively. The incidence of residual NMB was 63.5% (95% confidence interval, 57.4%-69.6%) at tracheal extubation and 56.5% (95% confidence interval, 49.8%-63.3%) at arrival at the PACU. In an exploratory analysis, no statistically significant differences were observed in the incidence of residual NMB according to gender, age, body mass index, ASA physical status, type of surgery, or comorbidities (all P > 0.13)., Conclusions: Residual paralysis is common at tracheal extubation and PACU arrival, despite qualitative neuromuscular monitoring and the use of neostigmine. More effective detection and management of NMB is needed to reduce the risks associated with residual NMB.

Purpose: The use of helium for insufflation during laparoscopic surgery avoids hypercarbia and acidosis associated with absorbed CO2, but the effects of helium gas embolism are unknown. We compared the effects of CO2 with He gas embolism on survival, haemodynamic variables, oxygenation, and ventilation in pigs., Methods: Anaesthetized juvenile pigs were given progressively larger boluses of either CO2 (n = 5) or He (n = 4) into the right atrium. Measurements of haemodynamic variables, oxygenation, and PETCO2 were made before and after each gas injection., Results: All animals survived injection of 300 ml CO2 while no animal survived more than 120 ml He (P < 0.01). Mean arterial pressure decreased more after 60 ml He (99 +/- 14 to 44 +/- 20 mmHg) than after 60 ml CO2 (110 +/- 12 to 88 +/- 14 mmHg, P < 0.001). Cardiac output did not change at any injection volume. The PETCO2 decreased more after 60 ml He (30 +/- 2 to 3 +/- 6 mmHg) than after 60 ml CO2 (35 +/- 3 to 30 +/- 3 mmHg, P < 0.001). Only the He group showed a decrease in PaO2 (190 +/- 51 to 68 +/- 22 mmHg at 60 ml, P < 0.05)., Conclusion: Helium gas embolism has a greater deleterious effect than CO2 gas embolism on survival, MAP, PETCO2, and PaO2. These different effects of gas embolism should be recognized when considering the use of helium or other insoluble gases for abdominal laparoscopic insufflation.

We studied the effect of positive end-expiratory pressure (PEEP) on the quantity and distribution of pulmonary extravascular water (PEW) and on lung mechanics and gas exchange in dogs with high pressure pulmonary edema. Lung volumes, intrapulmonary shunt (Qs/Qt), and dynamic compliance (Cdyn) were measured before (baseline) and after (postinfusion) administration of Ringer's Lactate (25% body weight) to maintain pulmonary wedge pressure between 35 and 40 cm H2O in 16 dogs. Animals were then randomly assigned to a control group (n = 8), ventilated to maintain normocarbia for 1.5 h, and to a PEEP group (n = 8) similarly ventilated with the addition of 10 cm H2O PEEP. After final measurements (1.5 h) and the injection of 51Cr tagged red blood cells, the dogs were killed and right lower lobes were excised and processed for morphometric examination and calculation of PEW by the gravimetric technique. The cuff area/vascular area ratios were measured on all extra-alveolar vessels, and total cuff H2O as well as the cuff H2O/PEW ratio was calculated. Postinfusion, Qs/Qt increased and functional residual capacity (FRC) and Cdyn decreased in both groups. At 1.5 h the PEEP group showed significant improvement in Qs/Qt, FRC, and Cdyn (p less than 0.05). When compared with the control group, the PEEP group had similar amounts of PEW but a greater proportion of cuff H2O. We conclude that PEEP improves gas exchange and lung mechanics, and that it is associated with redistribution of lung water to the "extra-alveolar" interstitial space.