The Association Between Spontaneous Hyperventilation, Delayed Cerebral Ischemia, and Poor Neurological Outcome in Patients with 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.

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.

Prediction of in-hospital hypokalemia using machine learning and first hospitalization day records in patients with traumatic brain injury

AIMS

Hypokalemia is a common complication following traumatic brain injury, which may complicate treatment and lead to unfavorable outcomes. Identifying patients at risk of hypokalemia on the first day of admission helps to implement prophylactic treatment, reduce complications, and improve prognosis.

METHODS

This multicenter retrospective study was performed between January 2017 and December 2020 using the electronic medical records of patients admitted due to traumatic brain injury. A propensity score matching approach was adopted with a ratio of 1:1 to overcome overfitting and data imbalance during subgroup analyses. Five machine learning algorithms were applied to generate a best-performed prediction model for in-hospital hypokalemia. The internal fivefold cross-validation and external validation were performed to demonstrate the interpretability and generalizability.

RESULTS

A total of 4445 TBI patients were recruited for analysis and model generation. Hypokalemia occurred in 46.55% of recruited patients and the incidences of mild, moderate, and severe hypokalemia were 32.06%, 12.69%, and 1.80%, respectively. Hypokalemia was associated with increased mortality, while severe hypokalemia cast greater impacts. The logistic regression algorithm had the best performance in predicting decreased serum potassium and moderate-to-severe hypokalemia, with an AUC of 0.73 ± 0.011 and 0.74 ± 0.019, respectively. The prediction model was further verified using two external datasets, including our previous published data and the open-assessed Medical Information Mart for Intensive Care database. Linearized calibration curves showed no statistical difference (p > 0.05) with perfect predictions.

CONCLUSIONS

The occurrence of hypokalemia following traumatic brain injury can be predicted by first hospitalization day records and machine learning algorithms. The logistic regression algorithm showed an optimal predicting performance verified by both internal and external validation.

Changes in Cerebral Blood Flow and Diffusion-Weighted Imaging Lesions After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a common subtype of stroke and places a great burden on the family and society with a high mortality and disability rate and a poor prognosis. Many findings from imaging and pathologic studies have suggested that cerebral ischemic lesions visualized on diffusion-weighted imaging (DWI) in patients with ICH are not rare and are generally considered to be associated with poor outcome, increased risk of recurrent (ischemic and hemorrhagic) stroke, cognitive impairment, and death. In this review, we describe the changes in cerebral blood flow (CBF) and DWI lesions after ICH and discuss the risk factors and possible mechanisms related to the occurrence of DWI lesions, such as cerebral microangiopathy, cerebral atherosclerosis, aggressive early blood pressure lowering, hyperglycemia, and inflammatory response. We also point out that a better understanding of cerebral DWI lesions will be a key step toward potential therapeutic interventions to improve long-term recovery for patients with ICH.

Spontaneous Hyperventilation Is Common in Patients with Spontaneous Cerebellar Hemorrhage, and Its Severity Is Associated with Outcome

Background: The spontaneous hyperventilation (SHV) accompanying spontaneous cerebellar hemorrhage has yet to attract a sufficient amount of attention. This study aimed to analyze the incidence of SHV in spontaneous cerebellar hemorrhage patients and its risk factors as well as its association with the outcome. Methods: We retrospectively reviewed the medical records of all spontaneous cerebellar hemorrhage patients who underwent surgical treatment at Tongji Hospital from July 2018 to December 2020. Arterial blood gas (ABG) test results and clinical characteristics, including demographics, comorbidities, imaging features, laboratory tests, and therapy choices, were collected. The Glasgow Outcome Scale was used to assess the outcome at two weeks and six months after admission. Results: A total of 147 patients were included, and of these patients 44.9% had spontaneous hyperventilation. Hypertension (OR, 3.175; CI, 1.332–7.569), usage of sedation drugs (OR, 3.693; CI, 1.0563–8.724), and hypernatremia (OR, 2.803; CI, 1.070–7.340) seemed to positively correlate to SHV occurrence. Hematoma removal had an inverse association with SHV (OR, 0.176; CI, 0.068–0.460). Patients with poor and good outcomes had significant differences in pH, PaCO₂, and HCO₃⁻ values, and the severity of SHV was associated with the PaCO₂ level. Conclusions: Spontaneous hyperventilation is common in patients with spontaneous cerebellar hemorrhage, and its severity is associated with the outcome.

Association of Rebleeding and Delayed Cerebral Ischemia with Long-term Mortality Among 1-year Survivors After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND OBJECTIVE

The potential impact of rebleeding and Delayed Cerebral Ischemia (DCI) on long-term survival in patients with aneurysmal subarachnoid hemorrhage (aSAH) remained unclear. This study aimed to investigate whether DCI and rebleeding increase the risk of long-term all-cause mortality in patients with aSAH who survived the follow-up period of one year.

METHODS

We retrospectively collected data on patients with atraumatic aSAH who were still alive 12 months after aSAH occurrence between December 2013 and June 2019 from the electronic health system. Patients were then classified by the occurrence of rebleeding or DCI during hospitalization. Death records were obtained from an administrative database, the Chinese Household Registration Administration System, until April 20, 2021. Multivariable Cox proportional hazards models were used to compare overall survival in different groups. Sensitivity analysis was performed with propensity-score matching (PSM).

RESULTS

A total of 2,607 patients were alive one year after aSAH. The crude annual death rate from any cause among patients who had rebleeding (7.2 per 100 person-years) and patients who had DCI (3.7 per 100 person-years) during hospitalization was higher than that of patients with neither event (2.1 per 100 person-years). Multivariate analysis showed that rebleeding is an independent risk factor for long-term mortality (adjusted hazard ratio (aHR), 2.37; 95% confidence interval (CI), 1.47- 3.81). DCI was an independent prognostic factor of poorer overall survival (aHR, 2.09; 95% CI, 1.54-2.84).

CONCLUSION

Amongst patients alive one year after aSAH, rebleeding and DCI during hospitalization were independently associated with higher rates of long-term mortality.

Serum Lactate Dehydrogenase to Phosphate Ratio as an Independent Predictor for Adverse Outcome of Microsurgical Clipping for Ruptured Intracranial Aneurysm: A Propensity-Score Matching Analysis

Objective: In this study, we assessed the correlation between the lactate dehydrogenase (LDH) to phosphate ratio and the prognosis of microsurgical clippings for ruptured intracranial aneurysm (rIA) to test the hypothesis that the serum LDH to phosphate ratio could be a predictor of the outcome of microsurgical clipping for rIA. Methods: Records of rIA patients between 2012 and 2018 were retrospectively collected. Age, sex, Hunt-Hess grade, Fisher grade, medical history, aneurysm location, hydrocephalus, laboratory data including serum LDH, phosphate, and LDH to phosphate ratio, related complications, and the outcomes in 3 months were recorded. Results: A total of 1608 rIA patients in our institution were collected, and 856 patients treated by microsurgical clipping were enrolled. On admission, a significantly higher LDH-phosphate ratio was observed in patients with poor outcomes at 3 months (median ± SD, 200.175 ± 107.290 for mRS 0−2 vs. 323.826 ± 219.075 for mRS score 3−6; p = 0.000). An LDH to phosphate ratio of 226.25 in the receiver operating characteristic (ROC) curve was the optimal cutoff value to discriminate between good and poor outcomes at 3 months. The LDH to phosphate ratio ≥ 226.25 on admission was independently correlated with poor outcomes in rIA patients. In addition, Hunt and Hess grade, Fisher grade, pneumonia, and DIND were also independently correlated with poor outcomes. After removing the bias in essential clinical variables between patients with LDH to phosphate, ratio ≥ 226.25 versus <226.25 by PSM, the number of patients with poor outcomes at 3 months increased in patients with an LDH to phosphate ratio of ≥226.25 (p = 0.005). Conclusions: The LDH to phosphate ratio was a potential biomarker and could predict the unfavorable outcome of microsurgical clipping for rIA in 3 months, related to neuronal damage, cerebral hypoxia, and early brain injury after aneurysm ruptures.

C-reactive protein elevation predicts in-hospital deterioration after aneurysmal subarachnoid hemorrhage: a retrospective observational study

Background

There is increasing evidence that inflammation plays a role in the pathogenesis of aneurysmal subarachnoid hemorrhage (aSAH) and in the development of delayed cerebral ischemia (DCI). However, the assessment and interpretation of classically defined inflammatory parameters is difficult in aSAH patients. The objective of this study was to investigate the relationship between easily assessable findings (hyperventilation, fever, white blood cell count (WBC), and C-reactive protein (CRP)) and the occurrence of DCI and unfavorable neurological outcome at discharge in aSAH patients.

Methods

Retrospective analysis of prospectively collected data from a single center cohort. We evaluated the potential of clinical signs of inflammation (hyperventilation, fever) and simple inflammatory laboratory parameters CRP and WBC to predict unfavorable outcomes at discharge and DCI in a multivariate analysis. A cutoff value for CRP was calculated by Youden’s J statistic. Outcome was measured using the modified Rankin score at discharge, with an unfavorable outcome defined as modified Rankin scale (mRS) > 3.

Results

We included 97 consecutive aSAH patients (63 females, 34 males, mean age 58 years) in the analysis. Twenty-one (22%) had major disability or died by the time of hospital discharge. Among inflammatory parameters, CRP over 100 mg/dl on day 2 was an independent predictor for worse neurological outcome at discharge. The average C-reactive protein level in the first 14 days was higher in patients with a worse neurological outcome (96.6, SD 48.3 vs 56.3 mg/dl, SD 28.6) in the first 14 days after aSAH. C-reactive protein on day 2 was an indicator of worse neurological outcome. No inflammatory parameter was an independent predictor of DCI. After multivariate adjustment, DCI, increased age, and more than 1 day of mechanical ventilation were significant predictors of worse neurological outcome.

Conclusions

Early elevated CRP levels were a significant predictor of worse neurological outcome at hospital discharge and may be a useful marker of later deterioration in aSAH.

Blood Pressure Management After Intracerebral and Subarachnoid Hemorrhage: The Knowns and Known Unknowns

Blood pressure (BP) elevations often complicate the management of intracerebral hemorrhage and aneurysmal subarachnoid hemorrhage, the most serious forms of acute stroke. Despite consensus on potential benefits of BP lowering in the acute phase of intracerebral hemorrhage, controversies persist over the timing, mechanisms, and approaches to treatment. BP control is even more complex for subarachnoid hemorrhage, where there are rationales for both BP lowering and elevation in reducing the risks of rebleeding and delayed cerebral ischemia, respectively. Efforts to disentangle the evidence has involved detailed exploration of individual patient data from clinical trials through meta-analysis to determine strength and direction of BP change in relation to key outcomes in intracerebral hemorrhage, and which likely also apply to subarachnoid hemorrhage. A wealth of hemodynamic data provides insights into pathophysiological interrelationships of BP and cerebral blood flow. This focused update provides an overview of current evidence, knowledge gaps, and emerging concepts on systemic hemodynamics, cerebral autoregulation and perfusion, to facilitate clinical practice recommendations and future research.

Effects of hyperoxemia on aneurysmal subarachnoid hemorrhage outcomes: a systematic review and meta-analysis

OBJECTIVE

In recent years, hyperoxemia in the intensive care unit has received attention as potentially contributing to negative outcomes in the setting of cardiac arrest, ischemic stroke, and traumatic brain injury. The authors sought to evaluate whether hyperoxemia contributes to worse outcomes in the setting of aneurysmal subarachnoid hemorrhage (aSAH) and to summarize suggested pathophysiological mechanisms.

METHODS

A systematic literature review was conducted without date restrictions on the PubMed and Web of Science databases on September 15, 2021. All studies that assessed the relationship between patients treated for aSAH and hyperoxemia were eligible independent of the criteria used to define hyperoxemia. All nonclinical studies and studies that did not report outcome data specific to patients with aSAH were excluded. A total of 102 records were found and screened, resulting in assessment of 10 full-text studies, of which 7 met eligibility criteria. Risk of bias was assessed using the Downs and Black checklist. A meta-analysis on the pooled 2602 patients was performed, and forest plots were constructed. Additionally, a review of the literature was performed to summarize available data regarding the pathophysiology of hyperoxemia.

RESULTS

The included studies demonstrated an association between hyperoxemia and increased morbidity and mortality following aSAH. The criteria used to determine hyperoxemia varied among studies. Pooling of univariate data showed hyperoxemia to be associated with poor neurological outcome (OR 2.26, 95% CI 1.66-3.07; p < 0.001), delayed cerebral ischemia (DCI) (OR 1.91, 95% CI 1.31-2.78; p < 0.001), and increased incidence of poor neurological outcome or mortality as a combined endpoint (OR 2.36, 95% CI 1.87-2.97; p < 0.001). Pooling of multivariable effect sizes showed the same relationship for poor neurological outcome (OR 1.28, 95% CI 1.07-1.55; p = 0.01) and poor neurological outcome and mortality as a combined endpoint (OR 1.17, 95% CI 1.11-1.23; p < 0.001). Additionally, review of preclinical studies underlined the contribution of oxidative stress due to hyperoxemia to acute secondary brain injury and DCI.

CONCLUSIONS

Reported outcomes from the available studies have indicated that hyperoxemia is associated with worse neurological outcome, mortality, and DCI. These findings provide a general guideline toward avoiding hyperoxemia in the acute setting of aSAH. Further studies are needed to determine the optimal ventilation and oxygenation parameters for acute management of this patient population.

Admission Lower Serum Phosphate Ion Levels Predict Acute Hydrocephalus of Aneurysmal Subarachnoid Hemorrhage

Introduction: The relationship between serum phosphate ion (sPi) and the occurrence of acute hydrocephalus (aHCP) in aneurysmal subarachnoid hemorrhage (aSAH) remains largely unknown and controversial. The primary aim of this study was to investigate the association between sPi on admission and aHCP following aSAH.

Methods: The study included 635 patients over the age of 19 years diagnosed with aSAH in our institution from September 2012 to June 2018. Data on clinical characteristics, laboratory parameters, treatments, and outcomes were collected and analyzed. The association between lower sPi levels and aHCP was assessed in univariate and multivariate analyses. Propensity-score matching (PSM) analysis was performed to reduce significant differences in baseline characteristics between the aHCP group and non-HCP group.

Results: The overall incidence of aHCP following aSAH was 19.37% (123/512). Lower sPi levels were detected in patients with aHCP compared with those without [0.86 (0.67–1.06) vs. 1.04 (0.84–1.21) mmol/L] in the univariate analysis. In the multivariate analysis, lower sPi level, high modified Fisher (mFisher) grade, and high Hunt-Hess grade were associated with aHCP [odds ratios (OR) 1.729, 95% confidence interval (CI) 1.139–2.623, p = 0.01; mFisher OR 0.097,95% CI 0.055–0.172, p < 0.001; Hunt-Hess, OR 0.555, 95% CI 0.320–0.961, P = 0.036]. After PSM, the matched aHCP group had a significantly lower sPi level than the matched non-aHCP group [0.86 (0.67–1.06) vs. 0.94 (0.76–1.12) mmol/L, p = 0.044]. The area under the curve (AUC) of the sPi level and the logistic regression model based on these predictors (sPi, Hunt-Hess grade, and mFisher grade) was 0.667 and 0.840 (sensitivity of 88.6% and specificity of 68.4%) for predicting aHCP, respectively.

Conclusions: Lower sPi levels predict the occurrence of aHCP, and the model constructed by sPi levels, Hunt-Hess grade, and mFisher grade markedly enhances the prediction of aHCP after aSAH.

Vascular Reactivity to Hypercapnia Is Impaired in the Cerebral and Retinal Vasculature in the Acute Phase After Experimental Subarachnoid Hemorrhage

Objective: Impaired cerebral blood flow (CBF) regulation, such as reduced reactivity to hypercapnia, contributes to the pathophysiology after aneurysmal subarachnoid hemorrhage (SAH), but temporal dynamics in the acute phase are unknown. Featuring comparable molecular regulation mechanisms, the retinal vessels participate in chronic and subacute stroke- and SAH-associated vessel alterations in patients and can be studied non-invasively. This study is aimed to characterize the temporal course of the cerebral and retinal vascular reactivity to hypercapnia in the acute phase after experimental SAH and compare the potential degree of impairment.

Methods: Subarachnoid hemorrhage was induced by injecting 0.5 ml of heparinized autologous blood into the cisterna magna of male Wistar rats using two anesthesia protocols [isoflurane/fentanyl n = 25 (Sham + SAH): Iso—Group, ketamine/xylazine n = 32 (Sham + SAH): K/X—Group]. CBF (laser speckle contrast analysis) and physiological parameters were measured continuously for 6 h. At six predefined time points, hypercapnia was induced by hypoventilation controlled via blood gas analysis, and retinal vessel diameter (RVD) was determined non-invasively.

Results: Cerebral reactivity and retinal reactivity in Sham groups were stable with only a slight attenuation after 2 h in RVD of the K/X—Group. In the SAH Iso—Group, cerebral and retinal CO2 reactivity compared to baseline was immediately impaired starting at 30 min after SAH (CBF p = 0.0090, RVD p = 0.0135) and lasting up to 4 h (p = 0.0136, resp. p = 0.0263). Similarly, in the K/X—Group, cerebral CO2 reactivity was disturbed early after SAH (30 min, p = 0.003) albeit showing a recovery to baseline after 2 h while retinal CO2 reactivity was impaired over the whole observation period (360 min, p = 0.0001) in the K/X—Group. After normalization to baseline, both vascular beds showed a parallel behavior regarding the temporal course and extent of impairment.

Conclusion: This study provides a detailed temporal analysis of impaired cerebral vascular CO2 reactivity starting immediately after SAH and lasting up to 6 h. Importantly, the retinal vessels participate in these acute changes underscoring the promising role of the retina as a potential non-invasive screening tool after SAH. Further studies will be required to determine the correlation with functional outcomes.

Acid-base balance and cerebrovascular regulation

The regulation and defence of intracellular pH is essential for homeostasis. Indeed, alterations in cerebrovascular acid-base balance directly affect cerebral blood flow (CBF) which has implications for human health and disease. For example, changes in CBF regulation during acid-base disturbances are evident in conditions such as chronic obstructive pulmonary disease and diabetic ketoacidosis. The classic experimental studies from the past 75+ years are utilized to describe the integrative relationships between CBF, carbon dioxide tension (PCO₂ ), bicarbonate (HCO₃ ^- ) and pH. These factors interact to influence (1) the time course of acid-base compensatory changes and the respective cerebrovascular responses (due to rapid exchange kinetics between arterial blood, extracellular fluid and intracellular brain tissue). We propose that alterations in arterial [HCO₃ ^- ] during acute respiratory acidosis/alkalosis contribute to cerebrovascular acid-base regulation; and (2) the regulation of CBF by direct changes in arterial vs. extravascular/interstitial PCO₂ and pH - the latter recognized as the proximal compartment which alters vascular smooth muscle cell regulation of CBF. Taken together, these results substantiate two key ideas: first, that the regulation of CBF is affected by the severity of metabolic/respiratory disturbances, including the extent of partial/full acid-base compensation; and second, that the regulation of CBF is independent of arterial pH and that diffusion of CO₂ across the blood-brain barrier is integral to altering perivascular extracellular pH. Overall, by realizing the integrative relationships between CBF, PCO₂ , HCO₃ ^- and pH, experimental studies may provide insights to improve CBF regulation in clinical practice with treatment of systemic acid-base disorders.

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.

Spontaneous hypocarbia without mechanical ventilation in preterm infants with cystic periventricular leukomalacia

AIM

Hypocarbia induced by mechanical ventilation has been considered a main cause of cystic periventricular leukomalacia (cPVL). However, hypocarbia may occur spontaneously in response to intracellular metabolic acidosis. We aimed to assess whether hypocarbia is more common during mechanical respiratory support than during spontaneous ventilation in infants with cPVL.

METHOD

In this single-centre, retrospective chart analysis, we compared partial pressure of carbon dioxide (pCO₂ ) during the first 96 hours of life in infants with cPVL during endotracheal mechanical ventilation, non-invasive respiratory support, or without respiratory support.

RESULTS

Cystic periventricular leukomalacia was diagnosed in 23 infants born between 2006 and 2017. Gestational age was 24 weeks in two infants and ranged between 28 and 32 weeks in 21 infants. In these 21 infants, pCO₂ less than 35 mm Hg during the first 96 ours of life accounted for 9/60 (15%) measurements during endotracheal mechanical ventilation, 16/116 (14%) during non-invasive respiratory support and 14/42 (33%) in infants without respiratory support (P = .014).

CONCLUSION

In our series of infants with cPVL, hypocarbia was more common without respiratory support than during endotracheal mechanical ventilation and non-invasive respiratory support. This would suggest that hypocarbia is a symptom rather than a cause of cPVL in these infants.

Hypocapnia, ischemic lesions, and outcomes after intracerebral hemorrhage

BACKGROUND

An association between spontaneous hyperventilation, delayed cerebral ischemia, and poor clinical outcomes has been reported in subarachnoid hemorrhage. We evaluated the relationship between early pCO₂ changes, ischemic lesions and outcomes in patients with intracerebral hemorrhage (ICH).

METHODS

Consecutive patients with spontaneous ICH were enrolled in an observational cohort study conducted between 2006 and 2019. Patient characteristics and discharge outcome were prospectively recorded. Arterial blood gas (ABG) measurements and mechanical ventilation settings in the first 72 h of admission were retrospectively collected. MRI images were adjudicated for diffusion-restricted lesions consistent with ischemia and distant from the hematoma. We examined the associations between pCO₂ changes, ischemic lesions, and discharge outcomes by univariate and adjusted analyses.

RESULTS

ABG data were available for 220 patients. Hyperventilation occurred in 52 (28%) cases and was not associated with clinical severity. Lower initial pCO₂ was associated with greater risk of in-hospital death (OR 0.94 per mmHg, 95%CI [0.89, 0.996], p = 0.042) after adjustment for ICH Score, pneumonia and mechanical ventilation requirements. MRI data were available for 33 patients. Lower pCO₂ was associated with a higher risk of ischemic lesions, except in patients with low initial systolic blood pressure (p < 0.05 for main and blood pressure interaction effects), after adjustment for other predictors.

CONCLUSIONS

In ICH patients with spontaneous ventilation, lower pCO₂ was independently associated with greater risk of in-hospital death. In patients with elevated initial blood pressure, who undergo blood pressure reduction per guideline recommendations, lower pCO₂ was associated with increased risk to develop ischemic lesions.

Protocolized Brain Oxygen Optimization in Subarachnoid Hemorrhage

BACKGROUND

Brain tissue hypoxia (P_btO₂ < 20 mmHg) is common after subarachnoid hemorrhage (SAH) and associated with poor outcome. Recent data suggest that brain oxygen optimization is feasible and reduces the time spent with P_btO₂ < 20 mmHg from 45 to 16% in patients with severe traumatic brain injury. Here, we intended to quantify the brain tissue hypoxia burden despite implementation of a protocolized treatment approach in poor-grade SAH patients and to identify the simultaneous occurrence of pathologic values potentially amenable to treatment.

METHODS

We present a bi-centric observational cohort study including 100 poor-grade SAH patients admitted to two tertiary care centers who underwent multimodal brain monitoring and were managed with a P_btO₂-targeted protocolized approach. P_btO₂ optimization (≥ 20 mmHg) included a stepwise neuro-intensive care approach, aiming to prevent low cerebral perfusion pressure (CPP), and blood hemoglobin, and to keep normocapnia, normoxemia, and normothermia. Based on routine blood gas analysis, hemoglobin, PaCO_2, and PaO₂ data were matched to 2-h averaged data of continuous CPP, P_btO₂, core temperature, and to hourly cerebral microdialysis (CMD) samples over the first 11 days.

RESULTS

Patients had a Glasgow Coma Scale of 3 (IQR 3-4) and were 58 years old (IQR 48-66). Overall incidence of brain tissue hypoxia was 25%, which was not different between both sites despite differences in the treatment approach. During brain tissue hypoxia, episodes of CPP < 70 mmHg (27%), PaCO₂ < 35 mmHg (19%), PaO₂ < 80 mmHg (14%), Hb < 9 g/dL (11%), metabolic crisis (CMD-lactate/pyruvate ratio > 40, and CMD-glucose < 0.7 mmol/L; 7%), and temperature > 38.3 °C (4%) were common.

CONCLUSIONS

Our results demonstrate that brain tissue hypoxia remains common despite implementation of a P_btO₂-targeted therapy in poor-grade SAH patients, suggesting room for further optimization.

Early Hyperoxia in The Intensive Care Unit is Significantly Associated With Unfavorable Neurological Outcomes in Patients With Mild-to-Moderate Aneurysmal Subarachnoid Hemorrhage

INTRODUCTION

Although oxygen administration is fundamental in the management of aneurysmal subarachnoid hemorrhage (SAH) patients in the acute stage, hyperoxia has harmful effects. The effects of hyperoxia on neurological outcomes in SAH patients are unclear. We aimed to examine the association of hyperoxia during the first 24 h in the intensive care unit (ICU) with unfavorable neurological outcomes in SAH patients.

METHODS

We retrospectively selected consecutive adult patients admitted to ICU for SAH between January 2009 and April 2018. We defined normoxia during the first 24 h in ICU as PaO2 of 60 mm Hg to 120 mm Hg, mild hyperoxia as PaO2 of 121 mm Hg to 200 mm Hg, moderate hyperoxia as PaO2 of 201 mm Hg to 300 mm Hg, and severe hyperoxia as PaO2 of >300 mm Hg. Univariate and multivariate analyses were performed to examine the association between hyperoxia during the first 24 h in ICU and unfavorable neurological outcomes (i.e., modified Rankin scale score of 3-6 at hospital discharge).

RESULTS

Among 196 SAH patients, 90 had unfavorable neurological outcomes. Hyperoxia was observed in 93.4% of patients. No significant association was observed between unfavorable neurological outcomes and hyperoxia in overall patients. However, we found that early hyperoxia in ICU was significantly associated with unfavorable neurological outcomes in SAH patients with Hunt and Kosnik (H&K) grades I to III (Relative risk, 1.84; 95% confidence interval, 1.10-2.94; P = 0.02).

CONCLUSIONS

Early hyperoxia was not associated with unfavorable neurological outcomes in overall SAH patients, but it was associated with unfavorable neurological outcomes in those with H&K grades I to III.

Impact of Hyperoxia and Hypocapnia on Neurological Outcomes in Patients with Aneurysmal Subarachnoid Hemorrhage: A Retrospective Study

In recent decades, there is increasing evidence suggesting that hyperoxia and hypocapnia are associated with poor outcomes in critically ill patients with cardiac arrest or traumatic brain injury. Yet, the impact of hyperoxia and hypocapnia on neurological outcome in patients with subarachnoid hemorrhage (SAH) has not been well studied. In the present study, we evaluated the impact of hyperoxia and hypocapnia on neurological outcomes in patients with aneurysmal SAH (aSAH). Patients with aSAH who were admitted to the intensive care unit (ICU) of a tertiary hospital in Hong Kong between January 2011 and December 2016 were retrospectively recruited. Patients' demographics, comorbidities, radiological findings, clinical grades of SAH, PO_2, and PCO₂ within 24 hours of ICU admission, and Glasgow Outcome Scale (GOS) at 3 months after admission were recorded. Patients with a GOS score of 3 or less were considered having poor neurological outcomes. Among the 244 patients with aSAH, 122 of them (50%) had poor neurological outcomes at 3 months. Early hyperoxia (PO₂ > 200 mmHg) and hypercapnia (PCO₂ > 45 mmHg) were more common among patients with poor neurological outcomes. Logistic regression analysis indicated that hyperoxia independently predicted poor neurological outcomes (OR 3.788, 95% CI 1.131-12.690, P=0.031). Classification tree analysis revealed that hypocapnia was associated with poor neurological outcomes in patients who were less critically ill (APACHE < 50) and without concomitant intracranial hemorrhage (ICH) or intraventricular hemorrhage (IVH) (adjusted P=0.006, χ ² = 7.452). These findings suggested that hyperoxia and hypocapnia may be associated with poor neurological outcomes in patients with aSAH.

Association of Admission Serum Glucose-Phosphate Ratio with Severity and Prognosis of Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Serum hyperglycemia and hypophosphatemia have been reported to be common in patients with aneurysmal subarachnoid hemorrhage (aSAH). This study aimed to explore whether admission serum glucose-phosphate ratio was associated with the severity and prognosis of aSAH.

METHODS

We retrospectively analyzed 198 patients with aSAH who were admitted within 24 hours of hemorrhage to a single academic hospital from June 2016 to September 2017. The following determinations were recorded: aSAH severity on admission, assessment by the World Federation of Neurosurgical Societies grading scale (WFNS), Fisher score defined according to the computed tomography results, and 3-month outcome assessed by the Glasgow Outcome Scale. A statistical analysis of the clinical and laboratory risk factors of poor outcome was conducted.

RESULTS

Admission serum glucose-phosphate ratio was increased in a WFNS grade-dependent manner and was higher in patients who had a poor outcome than in those who had a good outcome 3 months after aSAH. Multiple binomial logistic regression analysis showed that serum glucose-phosphate ratio, along with age, WFNS grade, and intraventricular hemorrhage, was associated with 3-month poor outcome after aSAH when we controlled for Fisher score, acute hydrocephalus, delayed cerebral ischemia, symptomatic cerebral vasospasm, serum glucose and phosphate levels, and glucose-potassium ratio. Receiver operating characteristic analysis showed that the area under the curve for glucose-phosphate ratio was significantly higher than age and intraventricular hemorrhage.

CONCLUSIONS

The study shows that the glucose-phosphate ratio is a potential biomarker that can reflect disease severity and prognosis in aSAH patients.

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

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.

Association of abnormal carbon dioxide levels with poor neurological outcomes in aneurysmal subarachnoid hemorrhage: a retrospective observational study

Background

In patients with aneurysmal subarachnoid hemorrhage (SAH), an association between hypocapnia and poor clinical outcomes has been reported. However, the optimal arterial carbon dioxide tension (PaCO₂) remains unknown. The present retrospective study aimed to examine the association of abnormal PaCO₂ levels with neurological outcomes and investigate the optimal target PaCO₂ level in patients with SAH.

Methods

We retrospectively selected consecutive adult patients hospitalized in the intensive care unit (ICU) for SAH between January 2009 and April 2017. Univariate and multivariate analyses were performed to identify the independent predictors of unfavorable neurological outcomes (i.e., modified Rankin scale score of 3–6 on hospital discharge).

Results

Among 158 patients with SAH, 73 had unfavorable neurological outcomes. During the first 2 weeks in the ICU, the median number of PaCO₂ measurements per patient was 43. The factors significantly associated with unfavorable neurological outcomes were age, Hunt and Kosnik grade, maximum lactate levels during the first 24 h, and maximum (odds ratio [OR], 1.12; 95% confidence interval [CI], 1.03–1.21; p < 0.01) and minimum PaCO₂ levels (OR, 0.81; 95% CI, 0.72–0.92; p < 0.01). Receiver operating characteristic curve analysis revealed that the cutoff range of PaCO₂ was 30.2–48.3 mmHg. Unfavorable neurological outcomes were noted in 78.8% of patients with PaCO₂ levels outside this range and in 22.8% of patients with PaCO₂ levels within this range.

Conclusions

Both the maximum and minimum PaCO₂ levels during ICU management in patients with SAH were significantly associated with unfavorable neurological outcomes. Further prospective studies are required to validate our findings and explore their clinical implications. Our findings may provide a scientific rationale for these future prospective studies.

Electronic supplementary material

The online version of this article (10.1186/s40560-018-0353-1) contains supplementary material, which is available to authorized users.

Interventions affecting blood pressure variability and outcomes after intubating patients with spontaneous intracranial hemorrhage

INTRODUCTION

Spontaneous intracranial hemorrhage (sICH) that increases intracranial pressure (ICP) is a life-threatening emergency often requiring intubation in Emergency Departments (ED). A previous study of intubated ED patients found that providing ≥5 interventions after initiating mechanical ventilation (pMVI) reduced mortality rate. We hypothesized that pMVIs would lower blood pressure variability (BPV) in patients with sICH and thus improve survival rates and neurologic outcomes.

METHOD

We performed a retrospective study of adults, who were transferred to a quaternary medical center between 01/01/2011 and 09/30/2015 for sICH, received an extraventricular drain during hospitalization. They were identified by International Classification of Diseases, version 9 (430.XX, 431.XX), and procedure code 02.21. Outcomes were BPV indices, death, and being discharged home.

RESULTS

We analyzed records from 147 intubated patients transferred from 40 EDs. Forty-one percent of patients received ≥5 pMVIs and was associated with lower median successive variation in systolic blood pressure (BP_SV) (31,[IQR 18-45) compared with those receiving 4 or less pMVIs (38[IQR 16-70]], p = 0.040). Three pMVIs, appropriate tidal volume, sedative infusion, and capnography were significantly associated with lower BPV. In addition to clinical factors, BP_SV (OR 26; 95% CI 1.2, >100) and chest radiography (OR 0.3; 95% CI 0.09, 0.9) were associated with mortality rate. Use of quantitative capnography (OR 8.3; 95%CI, 4.7, 8.8) was associated with increased likelihood of being discharged home.

CONCLUSIONS

In addition to disease severity, individual pMVIs were significantly associated with BPV and patient outcomes. Emergency physicians should perform pMVIs more frequently to prevent BPV and improve patients' outcomes.

Reframing the Biological Basis of Neuroprotection Using Functional Genomics: Differentially Weighted, Time-Dependent Multifactor Pathogenesis of Human Ischemic Brain Damage

Background: Neuroprotection studies are generally unable to demonstrate efficacy in humans. Our specific hypothesis is that multiple pathophysiologic pathways, of variable importance, contribute to ischemic brain damage. As a corollary to this, we discuss the broad hypothesis that a multifaceted approach will improve the probability of efficacious neuroprotection. But to properly test this hypothesis the nature and importance of the multiple contributing pathways needs elucidation. Our aim is to demonstrate, using functional genomics, in human cardiac surgery procedures associated with cerebral ischemia, that the pathogenesis of perioperative human ischemic brain damage involves the function of multiple variably weighted proteins involving several pathways. We then use these data and literature to develop a proposal for rational design of human neuroprotection protocols.

Methods: Ninety-four patients undergoing deep hypothermic circulatory arrest (DHCA) and/or aortic valve replacement surgery had brain damage biomarkers, S100β and neurofilament H (NFH), assessed at baseline, 1 and 24 h post-cardiopulmonary bypass (CPB) with analysis for association with 92 single nucleotide polymorphisms (SNPs) (selected by co-author WAK) related to important proteins involved in pathogenesis of cerebral ischemia.

Results: At the nominal significance level of 0.05, changes in S100β and in NFH at 1 and 24 h post-CPB were associated with multiple SNPs involving several prospectively determined pathophysiologic pathways, but were not individually significant after multiple comparison adjustments. Variable weights for the several evaluated SNPs are apparent on regression analysis and, notably, are dissimilar related to the two biomarkers and over time post CPB. Based on our step-wise regression model, at 1 h post-CPB, SOD2, SUMO4, and GP6 are related to relative change of NFH while TNF, CAPN10, NPPB, and SERPINE1 are related to the relative change of S100B. At 24 h post-CPB, ADRA2A, SELE, and BAX are related to the relative change of NFH while SLC4A7, HSPA1B, and FGA are related to S100B.

Conclusions: In support of the proposed hypothesis, association SNP data suggest function of specific disparate proteins, as reflected by genetic variation, may be more important than others with variation at different post-insult times after human brain ischemia. Such information may support rational design of post-insult time-sensitive multifaceted neuroprotective therapies.

A Propensity Score Analysis of the Impact of Dexamethasone Use on Delayed Cerebral Ischemia and Poor Functional Outcomes After Subarachnoid Hemorrhage

OBJECTIVE

An inflammatory response occurs after aneurysmal subarachnoid hemorrhage (aSAH) and predicts poor outcomes. Glucocorticoids suppress inflammation and promote fluid retention. Dexamethasone is often administered after aSAH for postoperative cerebral edema and refractory headache. Our objective was to examine the impact of dexamethasone use on functional outcomes and delayed cerebral ischemia (DCI) after aSAH.

METHODS

Patients with aSAH admitted between 2010 and 2015 were included; the data source was a single-center subarachnoid hemorrhage registry. The intervention of interest was a dexamethasone taper used <7 days from ictus. The primary outcome was poor discharge functional outcome, with a modified Rankin Scale score >3. Other outcomes included DCI and infection. A propensity score for use of dexamethasone was calculated using a logistic regression model that included potential predictors of dexamethasone use and outcome. The impact of dexamethasone on outcomes of interest was calculated and the propensity score was controlled for.

RESULTS

A total of 440 patients with subarachnoid hemorrhage were admitted during the study period and 309 met eligibility criteria. Dexamethasone was administered in 101 patients (33%). A total of 127 patients (41%) had a discharge modified Rankin Scale score >3, 105 (34%) developed DCI, and 94 (30%) developed an infection. After propensity score analysis, dexamethasone use was associated with a significant reduction in poor functional outcomes (odds ratio [OR], 0.35; 95% confidence interval [CI], 0.19-0.66) but showed no significant association with DCI (OR, 0.93; 95% CI, 0.53-1.64) or infection (OR, 0.60; 95% CI, 0.34-1.06).

CONCLUSIONS

Dexamethasone use after aSAH was associated with a reduction in poor functional outcomes at discharge but not DCI, controlling for predictors of dexamethasone use.

Twenty-four-hour emergency intervention versus early intervention in aneurysmal subarachnoid hemorrhage

OBJECTIVE Recent observational data suggest that ultra-early treatment of ruptured aneurysms prevents rebleeding, thus improving clinical outcomes. However, advances in critical care management of patients with ruptured aneurysms may reduce the rate of rebleeding in comparison with earlier trials, such as the International Cooperative Study on the Timing of Aneurysm Surgery. The objective of the present study was to determine if an ultra-early aneurysm repair protocol will or will not significantly reduce the number of incidents of rebleeding following aneurysmal subarachnoid hemorrhage (SAH). METHODS A retrospective analysis of data from a prospectively collected cohort of patients with SAH was performed. Rebleeding was diagnosed as new or expanded hemorrhage on CT, which was determined by independent review conducted by multiple physicians. Preventability of rebleeding by ultra-early aneurysm clipping or coiling was also independently reviewed. Standard statistics were used to determine statistically significant differences between the demographic characteristics of those with rebleeding compared with those without. RESULTS Of 317 patients with aneurysmal SAH, 24 (7.6%, 95% CI 4.7-10.5) experienced rebleeding at any time point following initial aneurysm rupture. Only 1/24 (4.2%, 95% CI -3.8 to 12.2) incidents of rebleeding could have been prevented by a 24-hour ultra-early aneurysm repair protocol. The other 23 incidents could not have been prevented for the following reasons: rebleeding prior to admission to the authors' institution (14/23, 60.9%); initial diagnostic angiography negative for aneurysm (4/23, 17.4%); postoperative rebleeding (2/23, 8.7%); patient unable to undergo operation due to medical instability (2/23, 8.7%); intraoperative rebleeding (1/23, 4.3%). CONCLUSIONS At a single tertiary academic center, the overall rebleeding rate was 7.6% (95% CI 4.7-10.5) for those presenting with ruptured aneurysms. Implementation of a 24-hour ultra-early aneurysm repair protocol would only result in, at most, a 0.3% (95% CI -0.3 to 0.9) reduction in the incidence of rebleeding.

Neuropulmonology

Neuropulmonology refers to the complex interconnection between the central nervous system and the respiratory system. Neurologic injury includes traumatic brain injury, hemorrhage, stroke, and seizures, and in each there are far-reaching effects that can result in pulmonary dysfunction. Systemic changes can induce impairment of pulmonary function due to changes in the core structure and function of the lung. The conditions and disorders that often occur in these patients include aspiration pneumonia, neurogenic pulmonary edema, and acute respiratory distress syndrome, but also several abnormal respiratory patterns and sleep-disordered breathing. Lung infections, pulmonary edema - neurogenic or cardiogenic - and pulmonary embolus all are a serious barrier to recovery and can have significant effects on outcomes such as hospital course, prognosis, and mortality. This review presents the spectrum of pulmonary abnormalities seen in neurocritical care.

Respiratory Acid-Base Disorders in the Critical Care Unit

The incidence of respiratory acid-base abnormalities in the critical care unit (CCU) is unknown, although respiratory alkalosis is suspected to be common in this population. Abnormal carbon dioxide tension can have many physiologic effects, and changes in Pco₂ may have a significant impact on outcome. Monitoring Pco₂ in CCU patients is an important aspect of critical patient assessment, and identification of respiratory acid-base abnormalities can be valuable as a diagnostic tool. Treatment of respiratory acid-base disorders is largely focused on resolution of the primary disease, although mechanical ventilation may be indicated in cases with severe respiratory acidosis.

Higher Cerebrospinal Fluid pH may Contribute to the Development of Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage

Recent investigations have shown that many factors may cause delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH). To find new potential contributors to DCI, this retrospective study compared gas data in the cerebrospinal fluid (CSF) between patients with and without DCI. The subjects were 61 consecutive patients with SAH classified as Fisher group III on admission computed tomography scans, whose aneurysms were obliterated by clipping or coiling within 24 h post-SAH. Thirty-three patients were treated with CSF drainage. CSF samples were chronologically obtained from CSF drains or lumbar taps. Patients with DCI were more frequently treated with CSF drainage, especially cisternal drainage, and were associated with significantly higher pH and lower partial pressure of carbon dioxide (PCO₂) in the CSF compared with patients without DCI, although CSF concentrations of bicarbonate ion as well as arterial blood gas data were not different between the two groups. Total hemoglobin concentrations in the drained or tapped CSF were higher in patients with no DCI compared with patients with DCI at any sampling time, suggesting that CSF hemoglobin was not efficiently removed in patients with DCI. This study revealed higher CSF pH and lower CSF PCO₂ as new potential contributors to the development of DCI, which might result from inappropriate CSF drainage that failed to remove clot and acid metabolites in it efficiently. Both of the disturbed CSF gas and inappropriate CSF drainage may cause constriction of the arteries and arterioles, leading to DCI.