Decision tree-based machine learning analysis of intraoperative vasopressor use to optimize neurological improvement in acute spinal cord injury.

OBJECTIVE: Previous work has shown that maintaining mean arterial pressures (MAPs) between 76 and 104 mm Hg intraoperatively is associated with improved neurological function at discharge in patients with acute spinal cord injury (SCI). However, whether temporary fluctuations in MAPs outside of this range can be tolerated without impairment of recovery is unknown. This retrospective study builds on previous work by implementing machine learning to derive clinically actionable thresholds for intraoperative MAP management guided by neurological outcomes. METHODS: Seventy-four surgically treated patients were retrospectively analyzed as part of a longitudinal study assessing outcomes following SCI. Each patient underwent intraoperative hemodynamic monitoring with recordings at 5-minute intervals for a cumulative 28,594 minutes, resulting in 5718 unique data points for each parameter. The type of vasopressor used, dose, drug-related complications, average intraoperative MAP, and time spent in an extreme MAP range (< 76 mm Hg or > 104 mm Hg) were collected. Outcomes were evaluated by measuring the change in American Spinal Injury Association Impairment Scale (AIS) grade over the course of acute hospitalization. Features most predictive of an improvement in AIS grade were determined statistically by generating random forests with 10,000 iterations. Recursive partitioning was used to establish clinically intuitive thresholds for the top features. RESULTS: At discharge, a significant improvement in AIS grade was noted by an average of 0.71 levels (p = 0.002). The hemodynamic parameters most important in predicting improvement were the amount of time intraoperative MAPs were in extreme ranges and the average intraoperative MAP. Patients with average intraoperative MAPs between 80 and 96 mm Hg throughout surgery had improved AIS grades at discharge. All patients with average intraoperative MAP > 96.3 mm Hg had no improvement. A threshold of 93 minutes spent in an extreme MAP range was identified after which the chance of neurological improvement significantly declined. Finally, the use of dopamine as compared to norepinephrine was associated with higher rates of significant cardiovascular complications (50% vs 25%, p < 0.001). CONCLUSIONS: An average intraoperative MAP value between 80 and 96 mm Hg was associated with improved outcome, corroborating previous results and supporting the clinical verifiability of the model. Additionally, an accumulated time of 93 minutes or longer outside of the MAP range of 76-104 mm Hg is associated with worse neurological function at discharge among patients undergoing emergency surgical intervention for acute SCI.

Assessment of a noninvasive cerebral oxygenation monitor in patients with severe traumatic brain injury.

OBJECT: Development of a noninvasive monitor to assess cerebral oxygenation has long been a goal in neurocritical care. The authors evaluated the feasibility and utility of a noninvasive cerebral oxygenation monitor, the CerOx 3110, which uses near-infrared spectroscopy and ultrasound to measure regional cerebral tissue oxygenation in patients with severe traumatic brain injury (TBI), and compared measurements obtained using this device to those obtained using invasive cerebral monitoring. METHODS: Patients with severe TBI admitted to the intensive care unit at Hadassah-Hebrew University Hospital requiring intracranial pressure (ICP) monitoring and advanced neuromonitoring were included in this study. The authors assessed 18 patients with severe TBI using the CerOx monitor and invasive advanced cerebral monitors. RESULTS: The mean age of the patients was 45.3 ± 23.7 years and the median Glasgow Coma Scale score on admission was 5 (interquartile range 3-7). Eight patients underwent unilateral decompressive hemicraniectomy and 1 patient underwent craniotomy. Sixteen patients underwent insertion of a jugular bulb venous catheter, and 18 patients underwent insertion of a Licox brain tissue oxygen monitor. The authors found a strong correlation (r = 0.60, p < 0.001) between the jugular bulb venous saturation from the venous blood gas and the CerOx measure of regional cerebral tissue saturation on the side ipsilateral to the catheter. A multivariate analysis revealed that among the physiological parameters of mean arterial blood pressure, ICP, brain tissue oxygen tension, and CerOx measurements on the ipsilateral and contralateral sides, only ipsilateral CerOx measurements were significantly correlated to jugular bulb venous saturation (p < 0.001). CONCLUSIONS: Measuring regional cerebral tissue oxygenation with the CerOx monitor in a noninvasive manner is feasible in patients with severe TBI in the neurointensive care unit. The correlation between the CerOx measurements and the jugular bulb venous measurements of oxygen saturation indicate that the CerOx may be able to provide an estimation of cerebral oxygenation status in a noninvasive manner.

Malaria in India: the center for the study of complex malaria in India.

Malaria is a major public health problem in India and one which contributes significantly to the overall malaria burden in Southeast Asia. The National Vector Borne Disease Control Program of India reported ∼1.6 million cases and ∼1100 malaria deaths in 2009. Some experts argue that this is a serious underestimation and that the actual number of malaria cases per year is likely between 9 and 50 times greater, with an approximate 13-fold underestimation of malaria-related mortality. The difficulty in making these estimations is further exacerbated by (i) highly variable malaria eco-epidemiological profiles, (ii) the transmission and overlap of multiple Plasmodium species and Anopheles vectors, (iii) increasing antimalarial drug resistance and insecticide resistance, and (iv) the impact of climate change on each of these variables. Simply stated, the burden of malaria in India is complex. Here we describe plans for a Center for the Study of Complex Malaria in India (CSCMi), one of ten International Centers of Excellence in Malaria Research (ICEMRs) located in malarious regions of the world recently funded by the National Institute of Allergy and Infectious Diseases, National Institutes of Health. The CSCMi is a close partnership between Indian and United States scientists, and aims to address major gaps in our understanding of the complexity of malaria in India, including changing patterns of epidemiology, vector biology and control, drug resistance, and parasite genomics. We hope that such a multidisciplinary approach that integrates clinical and field studies with laboratory, molecular, and genomic methods will provide a powerful combination for malaria control and prevention in India.

Critical care assessment and management of acute ischemic stroke.

The resuscitation and treatment of patients with an acute stroke has evolved measurably during the past 2 decades. Acute ischemic stroke represents a true emergency where time is crucial and, therefore, evaluation and treatment often proceed simultaneously. Advanced imaging techniques can provide information about the state of brain perfusion, metabolism, and the cerebrovascular anatomy to help identify patients with viable brain tissue who may derive the greatest benefit from available therapies. Currently, several agents are available for rapid restoration of perfusion to ischemic brain. These include intravenous administration of recombinant tissue-type plasminogen activator (tPA), which is effective within a 3-hour period, and intraarterial thrombolytic therapy, which may be effective within 6 hours. In addition, newer agents such as ancrod and abciximab may be effective within the acute time period. Optimal care requires a multidisciplinary approach with attention to a wide variety of therapeutic issues while maintaining adequate brain perfusion to reverse or halt the ischemic process. Herein, the author examines the important therapeutic concerns in the critical care management of ischemic stroke, including the management of elevated intracranial pressure, elevated and low blood pressure, cardiac complications, and potential metabolic disturbances.