PurposeDespite growing evidence supporting the potential benefits of higher end-tidal carbon dioxide (ETCO2) levels in surgical patients, there is still insufficient data to formulate guidelines for ideal intraoperative ETCO2 targets. As it is unclear which intraoperative ETCO2 levels are currently used and whether these levels have changed over time, we investigated the practice pattern using the Multicenter Perioperative Outcomes Group database.MethodsThis retrospective, observational, multicentre study included 317,445 adult patients who received general anesthesia for non-cardiothoracic procedures between January 2008 and September 2016. The primary outcome was a time-weighted average area-under-the-curve (TWA-AUC) for four ETCO2 thresholds (< 28, < 35, < 45, and > 45 mmHg). Additionally, a median ETCO2 was studied. A Kruskal-Wallis test was used to analyse differences between years. Random-effect multivariable logistic regression models were constructed to study variability.ResultsBoth TWA-AUC and median ETCO2 showed a minimal increase in ETCO2 over time, with a median [interquartile range] ETCO2 of 33 [31.0–35.0] mmHg in 2008 and 35 [33.0–38.0] mmHg in 2016 (P <0.001). A large inter-hospital and inter-provider variability in ETCO2 were observed after adjustment for patient characteristics, ventilation parameters, and intraoperative blood pressure (intraclass correlation coefficient 0.36; 95% confidence interval, 0.18 to 0.58).ConclusionsBetween 2008 and 2016, intraoperative ETCO2 values did not change in a clinically important manner. Interestingly, we found a large inter-hospital and inter-provider variability in ETCO2 throughout the study period, possibly indicating a broad range of tolerance for ETCO2, or a lack of evidence to support a specific targeted range. Clinical outcomes were not assessed in this study and they should be the focus of future research.Electronic supplementary materialThe online version of this article (10.1007/s12630-018-1249-1) contains supplementary material, which is available to authorized users.

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EDITOR’S PERSPECTIVE What We Already Know about This Topic It remains unknown what end-tidal carbon dioxide and mean arterial pressure are optimal for surgical management of patients with an aneurysmal subarachnoid hemorrhage What This Article Tells Us That Is New The investigators retrospectively evaluated 1,099 patients who had endovascular coiling or surgical clipping for subarachnoid hemorrhages There were no clinically important or statistical significant associations between either end-tidal carbon dioxide or mean arterial pressure thresholds and Glasgow Outcome Scale at discharge or three months Other prognostic factors are more important than carbon dioxide and blood pressure, at least within the observed clinical ranges Background Hypocapnia, hypotension, and hypertension during aneurysm occlusion in patients with an aneurysmal subarachnoid hemorrhage may lead to a poor prognosis, but evidence for end-tidal carbon dioxide (ETco2) and mean arterial pressure (MAP) targets is lacking. Within the ranges of standardized treatment, the authors aimed to study the association between hypocapnia (Paco2 &lt; 35 mmHg), hypotension (MAP &lt; 80 mmHg), and hypertension (MAP &gt;100 mmHg) during general anesthesia for aneurysm occlusion and neurologic outcome. Methods This retrospective observational study included patients who underwent early aneurysm occlusion after an aneurysmal subarachnoid hemorrhage under general anesthesia. ETco2 and MAP were summarized per patient as the mean and time-weighted average area under the curve for various absolute (ETco2 &lt; 30, &lt; 35, &lt; 40, &lt; 45 mmHg; and MAP &lt; 60, &lt; 70, &lt; 80, &gt; 90, &gt; 100 mmHg) and relative thresholds (MAP &lt; 70%, &lt; 60%, &lt; 50%). Clinical outcome was assessed with the Glasgow Outcome Scale at discharge and at three months, as primary and secondary outcome measure, respectively. Results Endovascular coiling was performed in 578 patients, and 521 underwent neurosurgical clipping. Of these 1,099 patients, 447 (41%) had a poor neurologic outcome at discharge. None of the ETco2 and MAP ranges found within the current clinical setting were associated with a poor neurologic outcome at discharge, with an adjusted risk ratio for any ETco2 value less than 30 mmHg of 0.95 (95% CI, 0.81 to 1.10; P &lt; 0.496) and an adjusted risk ratio for any MAP less than 60 mmHg of 0.94 (95% CI, 0.78 to 1.14; P &lt; 0.530). These results were not influenced by preoperative neurologic condition, treatment modality and timing of the intervention. Comparable results were obtained for neurologic outcome at three months. Conclusions Within a standardized intraoperative treatment strategy in accordance with current clinical consensus, hypocapnia, hypotension, and hypertension during aneurysm occlusion were not found to be associated with a poor neurologic outcome at discharge in patients with an aneurysmal subarachnoid hemorrhage.

Background: Patients undergoing cerebral bypass surgery are prone to cerebral hypoperfusion. Currently, arterial blood pressure is often increased with vasopressors to prevent cerebral ischaemia. However, this might cause vasoconstriction of the graft and cerebral vasculature and decrease perfusion. We hypothesised that cardiac output, rather than arterial blood pressure, is essential for adequate perfusion and aimed to determine whether dobutamine administration resulted in greater graft perfusion than phenylephrine administration. Methods: This randomised crossover study included 10 adult patients undergoing cerebral bypass surgery. Intraoperatively, patients randomly and sequentially received dobutamine to increase cardiac index or phenylephrine to increase mean arterial pressure (MAP). An increase of >10% in cardiac index or >10% in MAP was targeted, respectively. Before both interventions, a reference phase was implemented. The primary outcome was the absolute difference in graft flow between the reference and intervention phase. We compared the absolute flow difference between each intervention and constructed a random-effect linear regression model to explore treatment and carry-over effects. Results: Graft flow increased with a median of 4.1 (inter-quartile range [IQR], 1.7e12.0] ml min À1) after dobutamine administration and 3.6 [IQR, 1.3e7.8] ml min À1 after phenylephrine administration (difference e0.6 ml min À1 ; 95% confidence interval [CI], e14.5 to 5.3; P¼0.441). There was no treatment effect (0.9 ml min À1 ; 95% CI, 0.0e20.1; P¼0.944) and no carry-over effect. Conclusions: Both dobutamine and phenylephrine increased graft flow during cerebral bypass surgery, without a preference for one method over the other. Clinical trial registration: Netherlands Trial Register, NL7077 (https://www.trialregister.nl/trial/7077).