Timing of Intraoperative Transitions of Care Among Anesthesiologists Is Not Associated With Postoperative Adverse Outcomes: Retrospective Cohort Study.

BACKGROUND: The majority of published research suggests that anesthesia handovers during major surgical procedures are associated with unintended harmful consequences. It is still unclear if the number or quality of the transition of care is the main driver of the adverse outcomes. There is even less data if the timing of the anesthesiologist handovers during the critical portion of the anesthetic continuum (induction or emergence versus surgical period) plays a role in patient outcomes. Therefore, we investigated if the anesthesiologist handovers during induction and emergence are associated with adverse patient outcomes. METHODS: This retrospective investigation included noncardiac surgical procedures occurring between January 1, 2012 and December 31, 2019 that had exactly 1 attending anesthesiologist handover. We categorized transitions of care between attending anesthesiologists as being before incision, between incision and closing, and after closing. Our primary outcome was a composite of 6 categories of surgical complications and in-hospital mortality. We created logistic generalized estimating equation models to estimate the average relative effect odds ratio between each pair of the 3 transition timing groups across the components of the composite outcome. Inverse probability of treatment weights were used to mitigate confounding on a host of baseline variables. We used Bonferroni correction to adjust for multiple comparisons between the transition groups. RESULTS: In total, we studied 36,937 procedures with exactly 1 attending anesthesiologist handover. Of these records, 4370 had the transition during induction, 24,999 between incision and closure, and 7568 during emergence. No differences were found between the transition periods and the composite outcome. The estimated average relative effect odds ratio (98.3% confidence interval [CI]) across the components of the composite outcome was as follows: (1.0002 [0.81-1.24], P = .99) between the induction and surgical period; (1.10 [0.87-1.40], P = .32) between the induction and emergence periods; and (0.91 [0.79-1.04], P = .08) between the emergence and surgical periods. CONCLUSIONS: Timing of intraoperative handover among attending anesthesiologists during noncardiac surgery is not associated with adverse patient outcomes.

Perioperative Supplemental Oxygen and Postoperative Nausea and Vomiting: Subanalysis of a Trial, Systematic Review, and Meta-analysis.

BACKGROUND: Intraoperative supplemental oxygen may reduce postoperative nausea and vomiting by mitigating hypoxic stress on the gastrointestinal tract. The authors therefore tested the hypothesis that supplemental oxygen reduces nausea and vomiting in adults recovering from colorectal surgery at the Cleveland Clinic between January 28, 2013, and March 11, 2016. METHODS: Initially, the authors conducted an unplanned subanalysis of a previous trial that evaluated the effect of 80% versus 30% intraoperative inspired oxygen on surgical site infection. Specifically, they assessed the effect of 80% versus 30% oxygen concentration on the incidence of postoperative nausea and/or vomiting. Thereafter, the authors conducted a systematic review and meta-analysis of the effect of supplemental oxygen on postoperative nausea and vomiting. RESULTS: The authors' underlying analysis included 5,057 colorectal surgeries on 4,001 patients. For 2,554 surgeries, assignment was to 80% oxygen, and in 2,503 surgeries, to 30%. Postoperative nausea and vomiting was 852 of 2,554 (33%) in 80% oxygen and 814 of 2,503 (33%) in 30% oxygen. The estimated relative risk (95% CI) of 80% versus 30% oxygen on postoperative nausea and vomiting was 1.04 (0.96 to 1.12) in a generalized estimating equation model adjusting for within-patient correlation for patients with multiple surgeries, P = 0.355. Furthermore, supplemental oxygen did not reduce antiemetic use (P = 0.911) or the severity of nausea and vomiting (P = 0.924). The authors' meta-analysis included 10 qualifying trials (6,749 patients) and did not find a difference in postoperative nausea and vomiting: relative risk, 0.97 [95% CI, 0.86 to 1.08], P = 0.55, I2 = 52%. CONCLUSIONS: The incidence of postoperative nausea and vomiting did not differ in patients assigned to 80% or 30% inspired oxygen. A meta-analysis of available trials similarly indicated that supplemental intraoperative oxygen does not reduce postoperative nausea and vomiting. Therefore, supplemental oxygen should not be given in the expectation that it will reduce nausea and vomiting.

The Association Between Mild Intraoperative Hypotension and Stroke in General Surgery Patients.

BACKGROUND: Intraoperative hypotension may contribute to perioperative strokes. We therefore tested the hypothesis that intraoperative hypotension is associated with perioperative stroke. METHODS: After institutional review board approval for this case-control study, we identified patients who had nonneurological, noncardiac, and noncarotid surgery under general anesthesia at the Cleveland Clinic between 2005 and 2011 and experienced a postoperative stroke. Control patients not experiencing postoperative stroke were matched in a 4-to-1 ratio using propensity scores and restriction to the same procedure type as stroke patients. The association between intraoperative hypotension, measured as time-integrated area under a mean arterial pressure (MAP) of 70 mm Hg, and postoperative stroke was assessed using zero-inflated negative binomial regression. RESULTS: Among 106 337 patients meeting inclusion criteria, we identified 120 who had confirmed postoperative stroke events based on manual chart review. Four-to-one propensity matching yielded a final matched sample of 104 stroke cases and 398 controls. There was no association between stroke and intraoperative hypotension. Stroke patients were not more likely than controls to have been hypotensive (odds ratio, 0.49 [0.18-1.38]), and among patients with intraoperative hypotension, stroke patients did not experience a greater degree of hypotension than controls (ratio of geometric means, 1.07 [0.76-1.53]). CONCLUSIONS: In our propensity score-matched case-control study, we did not find an association between intraoperative hypotension, defined as MAP < 70 mm Hg, and postoperative stroke.

Assessing intravascular volume by difference in pulse pressure in pigs submitted to graded hemorrhage.

We assessed changes in intravascular volume monitored by difference in pulse pressure (dPP%) after stepwise hemorrhage in an experimental pig model. Six pigs (23-25 kg) were anesthetized (isoflurane 1.5 vol%) and mechanically ventilated to keep end-tidal CO2 (etCO2) at 35 mmHg. A PA-catheter and an arterial catheter were placed via femoral access. During and after surgery, animals received lactated Ringer's solution as long as they were considered volume responders (dPP>13%). Then animals were allowed to stabilize from the induction of anesthesia and insertion of catheters for 30 min. After stabilization, baseline measurements were taken. Five percent of blood volume was withdrawn, followed by another 5%, and then in 10%-increments until death from exsanguination occurred. After withdrawal of 5% of blood volume, all pigs were considered volume responders (dPP>13%); dPP rose significantly from 6.1+/-3.3% to 19.4+/-4.2%. The regression analysis of stepwise hemorrhage revealed a linear relation between blood loss (hemorrhage in %) and dPP (y=0.99*x+14; R2=0.7764; P<.0001). In addition, dPP was the only parameter that changed significantly between baseline and a blood loss of 5% (P<0.01), whereas cardiac output, stroke volume, heart rate, MAP, central venous pressure, pulmonary artery occlusion pressure, and systemic vascular resistance, respectively, remained unchanged. We conclude that in an experimental hypovolemic pig model, dPP correlates well with blood loss.