Blood Pressure and End-tidal Carbon Dioxide Ranges during Aneurysm Occlusion and Neurologic Outcome after an Aneurysmal Subarachnoid Hemorrhage

Intraoperative Blood Pressure and Carbon Dioxide Values during Aneurysmal Repair and the Outcomes after Aneurysmal Subarachnoid Hemorrhage

Cerebral autoregulation impairment is a critical aspect of subarachnoid hemorrhage (SAH)-induced secondary brain injury and is also shown to be an independent predictor of delayed cerebral ischemia (DCI) and poor neurologic outcomes. Interestingly, intraoperative hemodynamic and ventilatory parameters were shown to influence patient outcomes after SAH. The aim of the current study was to evaluate the association of intraoperative hypotension and hypocapnia with the occurrence of angiographic vasospasm, DCI, and neurologic outcomes at discharge. Intraoperative data were collected for 390 patients with aneurysmal SAH who underwent general anesthesia for aneurysm clipping or coiling between January 2010 and May 2018. We measured the mean intraoperative blood pressure and end-tidal carbon dioxide (ETCO2), as well as the area under the curve (AUC) for the burden of hypotension: SBP below 100 or MBP below 65 and hypocapnia (ETCO2 < 30), during the intraoperative period. The outcome measures were angiographic vasospasm, DCI, and the neurologic outcomes at discharge as measured by the modified Rankin scale score (an mRS of 0-2 is a good outcome, and 3-6 is a poor outcome). Univariate and logistic regression analyses were performed to evaluate whether blood pressure (BP) and ETCO2 variables were independently associated with outcome measures. Out of 390 patients, 132 (34%) developed moderate-to-severe vasospasm, 114 (29%) developed DCI, and 46% (169) had good neurologic outcomes at discharge. None of the measured intraoperative BP and ETCO2 variables were associated with angiographic vasospasm, DCI, or poor neurologic outcomes. Our study did not identify an independent association between the degree of intraoperative hypotension or hypocapnia in relation to angiographic vasospasm, DCI, or the neurologic outcomes at discharge in SAH patients.

Intraoperative arterial pressure and delayed cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage after surgical clipping: A retrospective cohort study

Background

Delayed cerebral ischemia (DCI) is the major predictor of poor outcomes in patients with aSAH. Previous studies have attempted to assess the relationship between controlling blood pressure and DCI. However, the management of intraoperative blood pressure in reducing the occurrence of DCI still remains inconclusive.

Methods

All patients with aSAH who received general anesthesia for surgical clipping between January 2015 and December 2020 were prospectively reviewed. Patients were divided in the DCI group or the non-DCI group depending on whether DCI occurred or not. Intraoperative arterial pressure was measured every minute and recorded in an electronic anesthesia recording system along with intraoperative medication and other vital signs. The initial neurological function score, aneurysm characteristics, surgical and anesthetic information, and outcomes were compared between the DCI and the non-DCI groups.

Results

Among 534 patients who were enrolled, a total of 164 (30.71%) patients experienced DCI. The baseline characteristics of patients were similar between the groups. The World Federation of Neurosurgical Societies (WFNS) Scale > 3, age ≥ 70 years, and the modified Fisher Scale > 2 were significantly higher in patients with DCI than those without. Though it was the second derivative of the regression analysis, 105 mmHg was adopted as the threshold for intraoperative hypotension and was not associated with DCI.

Conclusions

The threshold of 105 mmHg was adopted as intraoperative hypotension even though it was the second derivative of the regression analysis and could not be proved to be associated with delayed cerebral ischemia adjusted by the baseline severity of aSAH and age.

Blood pressure and the risk of rebleeding and delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

INTRODUCTION AND OBJECTIVE

Blood pressure is presumably related to rebleeding and delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (aSAH) and could serve as a target to improve outcome. We assessed the associations between blood pressure and rebleeding or DCI in aSAH-patients.

MATERIALS AND METHODS

In this observational study in 1167 aSAH-patients admitted to the intensive care unit (ICU), adjusted hazard ratio's (aHR) were calculated for the time-dependent association of blood pressure and rebleeding or DCI. The aHRs were presented graphically, relative to a reference mean arterial pressure (MAP) of 100 mmHg and systolic blood pressure (sBP) of 150 mmHg.

RESULTS

A MAP below 100 mmHg in the 6, 3 and 1 h before each moment in time was associated with a decreased risk of rebleeding (e.g. within 6 h preceding rebleeding: MAP = 80 mmHg: aHR 0.30 (95% confidence interval (CI) 0.11-0.80)). A MAP below 60 mmHg in the 24 h before each moment in time was associated with an increased risk of DCI (e.g. MAP = 50 mmHg: aHR 2.59 (95% CI 1.12-5.96)).

CONCLUSIONS

Our results suggest that a MAP below 100 mmHg is associated with decreased risk of rebleeding, and a MAP below 60 mmHg with increased risk of DCI.

Efficacy and safety of remifentanil dose titration to correct the spontaneous hyperventilation in aneurysmal subarachnoid haemorrhage: protocol and statistical analysis for a prospective physiological study

INTRODUCTION

Spontaneous hyperventilation (SHV) is common in aneurysmal subarachnoid haemorrhage (aSAH). The reduction in arterial partial pressure of carbon dioxide (PaCO₂) may change the brain physiology, such as haemodynamics, oxygenation, metabolism and may lead to secondary brain injury. However, how to correct SHV safely and effectively in patients with aSAH has not been well investigated. The aim of this study is to investigate the efficacy and safety of remifentanil dose titration to correct hyperventilation in aSAH, as well as the effect of changes in PaCO₂ on cerebral blood flow (CBF).

METHODS AND ANALYSIS

This study is a prospective, single-centre, physiological study in patients with aSAH. The patients who were mechanically ventilated and who meet with SHV (tachypnoea combined with PaCO₂ <35 mm Hg and pH >7.45) will be enrolled. The remifentanil will be titrated to correct the SHV. The predetermined initial dose of remifentanil is 0.02 μg/kg/min and will be maintained for 30 min, and PaCO₂ and CBF will be measured. After that, the dose of remifentanil will be sequentially increased to 0.04, 0.06, and 0.08 μg/kg/min, and the measurements for PaCO₂ and CBF will be repeated 30 min after each dose adjustment and will be compared with their baseline values.

ETHICS AND DISSEMINATION

This study has been approved by the Institutional Review Board of Beijing Tiantan Hospital, Capital Medical University (KY 2021-006-02) and has been registered at ClinicalTrials.gov. The results of this study will be disseminated through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

NCT04940273.

Outlying End-Tidal Carbon Dioxide During General Anesthesia Is Associated With Postoperative Pulmonary Complications: A Multicenter Retrospective Observational Study From US Hospitals Between 2010 and 2017

BACKGROUND

Postoperative pulmonary complications (PPCs) occur in up to 33% of patients who undergo noncardiothoracic surgery. Emerging evidence suggests that permissive hypercapnia may reduce the risk of lung injury. We hypothesized that higher intraoperative end-tidal carbon dioxide (Etco2) concentrations would be associated with a decreased risk of PPCs.

METHODS

This retrospective, observational, multicenter study included patients undergoing general anesthesia for noncardiothoracic procedures (January 2010-December 2017). The primary outcome was PPC within 30 postoperative days. Secondary outcomes were PPC within 1 week, postoperative length of stay, and inhospital 30-day mortality. The association between these outcomes, median Etco2, and 4 time-weighted average area-under-the-curve (TWA-AUC) thresholds (<28, <35, <45, and >45 mm Hg) was explored using a multivariable mixed-effect model and by plotting associated risks.

RESULTS

Among 143,769 cases across 11 hospitals, 10,276 (7.1%) experienced a PPC. When compared to a baseline median Etco2 of 35 to 40 mm Hg, a median Etco2 >40 mm Hg was associated with an increase in PPCs within 30 days (median Etco2, 40-45 mm Hg; adjusted OR, 1.16 [99% confidence interval {CI}, 1.00-1.33]; P value = .008 and median Etco2, >45 mm Hg; OR, 1.64 [99% CI, 1.33-2.02]; P value < .001). The occurrence of any Etco2 value <28 mm Hg (ie, a positive TWA-AUC < 28 mm Hg) was associated with PPCs (OR, 1.40 [95% CI, 1.33-1.49]; P value < .001), mortality, and length of stay. Any Etco2 value >45 mm Hg (ie, a positive TWA-AUC >45 mm Hg) was also associated with PPCs (OR, 1.24 [95% CI, 1.17-1.31]; P < .001). The Etco2 range with the lowest incidence of PPCs was 35 to 38 mm Hg.

CONCLUSIONS

Both a very low (<28 mm Hg) and a high Etco2 (>45 mm Hg) were associated with PPCs within 30 days. The lowest PPC incidence was found in patients with an Etco2 of 35 to 38 mm Hg. Prospective studies are needed to clarify the relationship between postoperative PPCs and intraoperative Etco2.

Intraoperative end-tidal carbon dioxide and postoperative mortality in major abdominal surgery: a historical cohort study

PURPOSE

There is a paucity of data on the effect of intraoperative end-tidal carbon dioxide (EtCO₂) levels on postoperative mortality. The purpose of this study was to investigate the relationship between intraoperative EtCO₂ and 90-day mortality in patients undergoing major abdominal surgery under general anesthesia.

METHODS

We conducted a historical cohort study of patients undergoing major abdominal surgery under general anesthesia at Kyoto University Hospital. We measured the intraoperative EtCO₂, and patients with a mean EtCO₂ value < 35 mm Hg were classified as low EtCO₂. The time effect was determined based on minutes below an EtCO₂ of 35 mm Hg, and cumulative effects were evaluated by measuring the area under the threshold of 35 mm Hg for each patient.

RESULTS

Of 4,710 patients, 1,374 (29%) had low EtCO₂ and 55 (1.2%) died within 90 days of surgery. Multivariable Cox regression analysis-adjusted for age, American Society of Anesthesiologists Physical Status classification, sex, laparoscopic surgery, emergency surgery, blood loss, mean arterial pressure, duration of surgery, type of surgery, and chronic obstructive pulmonary disease-revealed an association between low EtCO₂ and 90-day mortality (adjusted hazard ratio, 2.2; 95% confidence interval [CI], 1.2 to 3.8; P = 0.006). In addition, severity of low EtCO₂ was associated with an increased 90-day mortality (area under the threshold; adjusted hazard ratio; 2.9, 95% CI, 1.2 to 7.4; P =0.02); for long-term exposure to an EtCO₂ < 35 mm Hg (≥ 226 min), the adjusted hazard ratio for increased 90-day mortality was 2.3 (95% CI, 0.9 to 6.0; P = 0.08).

CONCLUSION

A mean intraoperative EtCO₂ < 35 mm Hg was associated with increased postoperative 90-day mortality.

Intracranial Vascular Procedures

Anesthesia for intracranial vascular procedures is complex because it requires a balance of several competing interests and potentially can result in significant morbidity and mortality. Frequently, periods of ischemia, where perfusion must be maintained, are combined with situations that are high risk for hemorrhage. This review discusses the basic surgical approach to several common pathologies (intracranial aneurysms, arteriovenous malformations, and moyamoya disease) along with the goals for anesthetic management and specific high-yield recommendations.

Effects of end-tidal carbon dioxide levels in patients undergoing direct revascularization for Moyamoya disease and risk factors associated with postoperative complications

A history of transient ischemic attack, severity of disease, urinary output, hematocrit, hypocapnia, and hypotension during direct revascularization (superficial temporal artery to middle cerebral artery [STA-MCA]) in patients with Moyamoya disease (MMD) may lead to a poor prognosis, however, to our knowledge evidence for end-tidal carbon dioxide (ETCO2) targets is lacking. Within the ranges of standardized treatment, the article was primarily designed to study the risk factors associated with the neurologic outcomes during STA-MCA for MMD especially including ETCO2 ranges and the duration in different groups. The primary goals of this study were to investigate the risk factors for neurologic deterioration and explore the association between ETCO2 ranges and neurologic outcome during general anesthesia for STA-MCA.This retrospective observational study included 56 consecutively adult Moyamoya patients who underwent STA-MCA under general anesthesia between January 2015 and August 2019. ETCO2 was summarized per patient every 5 minutes. Clinical outcome was assessed with clinical presentation, computed tomography findings, magnetic resonance imaging findings, cerebral angiography, and the modified Rankin Scale scores at discharge as main outcome measure. The outcomes were also compared for the duration of surgery, anesthesia, and the length of stay.A total of 56 patients were studied, all patients had comprehensive ETCO2 measurements. The incidence of postoperative complications was 44.6% (25/56). There was no association between age, sex, hypertension, diabetes, smoking history, drinking history, sevoflurane use, invasive arterial blood pressure monitoring, combined encephalomyosynangiosis and postoperative complications. Duration of surgery (P = .04), anesthesia (P = .036), hospital stay (P = .023) were significant correlates of postoperative complications. In the multiple logistic regression model, they were not the significant predictors. The ETCO2 ranges and the length of time in different groups within the current clinical setting was not associated with postoperative complications (P > .05).Within a standardized intraoperative treatment strategy, we found that postoperative complications had no significant correlation with sex, age, hypertension, diabetes, smoking history, drinking history, invasive arterial blood pressure monitoring, combined encephalomyosynangiosis, or sevoflurane use. Further, hypocapnia and hypercapnia during STA-MCA were not found to be associated with postoperative complications in patients with MMD.

Perioperative Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is an acute neurologic emergency. Prompt definitive treatment of the aneurysm by craniotomy and clipping or endovascular intervention with coils and/or stents is needed to prevent rebleeding. Extracranial manifestations of aneurysmal subarachnoid hemorrhage include cardiac dysfunction, neurogenic pulmonary edema, fluid and electrolyte imbalances, and hyperglycemia. Data on the impact of anesthesia on long-term neurologic outcomes of aneurysmal subarachnoid hemorrhage do not exist. Perioperative management should therefore focus on optimizing systemic physiology, facilitating timely definitive treatment, and selecting an anesthetic technique based on patient characteristics, severity of aneurysmal subarachnoid hemorrhage, and the planned intervention and monitoring. Anesthesiologists should be familiar with evoked potential monitoring, electroencephalographic burst suppression, temporary clipping, management of external ventricular drains, adenosine-induced cardiac standstill, and rapid ventricular pacing to effectively care for these patients.

Appropriate Blood Pressure in Cerebral Aneurysm Clipping for Prevention of Delayed Ischemic Neurologic Deficits

Background

Delayed ischemic neurologic deficit (DNID) is a problem after cerebral aneurysm clipping. Intraoperative hypotension seems to be indicated as a risk factor, but it remains a controversial issue with varying low-blood pressure levels accepted.

Methods

A retrospective, hospital-based, case-control study was performed with patients who received general anesthesia for cerebral aneurysm clipping. 42 medical record charts were randomly selected and matched 1 : 2 (1 case with DNID : 2 controls without DNID) based on the type of general anesthetic techniques and severity of subarachnoid hemorrhage. The optimal cutoff points of hemodynamic response were calculated by the area under the curve.

Results

Data suggested that the optimal cutoff points for lowest blood pressure for prevention of DNID should be systolic blood pressure (SBP) of 95 mmHg (sensitivity of 78.6%; specificity of 53.6%), diastolic blood pressure (DBP) of 50 mmHg (sensitivity of 71.4%; specificity of 67.9%), and mean arterial pressure (MAP) of 61.7 mmHg (sensitivity of 85.7%; specificity of 35.7%). Furthermore, the optimal cutoff point mean difference baseline blood pressure was recommended as Δ SBP of 36 mmHg (sensitivity of 85.7%; specificity of 60.7%), Δ DBP of 27 mmHg (sensitivity of 92.9%; specificity of 71.4%), and Δ MAP of 32 mmHg (sensitivity of 92.9%; specificity of 85.7%). No significant difference between DNID and non-DNID groups was found for end-tidal carbon dioxide (ETCO₂) and has poor diagnostic value for predicting DNID.

Conclusion

To prevent DNID, we recommend that optimal blood pressure should not be lower than 95 for SBP, 50 for DBP, and 61.7 mmHg for MAP. Additionally, we suggest that Δ SBP, Δ DBP, and Δ MAP should be less than 36, 27, and 32 mmHg, respectively.

Hyperventilation in neurological patients: from physiology to outcome evidence

Hyperventilation is commonly used in neurological patients to decrease elevated intracranial pressure (ICP) or relax a tense brain. However, the potentially deleterious effects of hyperventilation may limit its clinical application. The aim of this review is to summarize the physiological and outcome evidence related to hyperventilation in neurological patients.

Neuroanesthesiology Update

This review is intended to provide a summary of the literature pertaining to the perioperative care of neurosurgical patients and patients with neurological diseases. General topics addressed in this review include general neurosurgical considerations, stroke, neurological monitoring, and perioperative disorders of cognitive function.

High-normal PaCO2 values might be associated with worse outcome in patients with subarachnoid hemorrhage - a retrospective cohort study

BACKGROUND

While both hypercapnia and hypocapnia are harmful in patients with subarachnoid hemorrhage (SAH), it is unknown whether high-normal P_aCO₂ values are better than low-normal values. We hypothesized that high-normal P_aCO₂ values have more detrimental than beneficial effects on outcome.

METHODS

Consecutive patients with aneurysmal subarachnoid hemorrhage (aSAH) requiring mechanical ventilation treated in a tertiary care university hospital were retrospectively analyzed regarding the influence of P_aCO₂ on favorable outcome, defined as modified Rankin scale score < 3 at discharge. Primary endpoint was the difference in the proportion of P_aCO₂ values above 40 mmHg in relation to all measured P_aCO₂ values between patients with favorable and unfavorable outcome.

RESULTS

150 patients were included. Median age was 57 years (p25:50, p75:64), median Hunt-Hess score was 4 (p25:3, p75:5). P_aCO₂ values were mainly within normal range (median 39.0, p25:37.5, p75:41.4). Patients with favorable outcome had a lower proportion of high-normal P_aCO₂ values above 40 mmHg compared to patients with unfavorable outcome (0.21 (p25:0.13, p75:0.50) vs. 0.4 (p25:0.29, p75:0.59)) resulting in a lower chance for favorable outcome (OR 0.04, 95% CI 0.00-0.55, p = 0.017). In multivariable analysis adjusted for Hunt-Hess score, pneumonia and length of stay, elevated P_aCO₂ remained an independent predictor of outcome (OR 0.05, 95% CI 0.00-0.81, p = 0.035).

CONCLUSIONS

A higher proportion of P_aCO₂ values above 40 mmHg was an independent predictor of outcome in patients with aSAH in our study. The results need to be confirmed in a prospective trial.