Intraoperative hypothermia during vascular neurosurgical procedures

Therapeutic hypothermia after cardiac arrest during living-donor liver transplant surgery: A case report

RATIONALE

Therapeutic hypothermia is an effective medical treatment for neurological recovery after cardiac arrest. Here, we describe a case of successful mild therapeutic hypothermia after cardiac arrest during living-donor liver transplantation.

PATIENT CONCERNS

A 54-year-old woman with alcoholic liver cirrhosis was admitted for living-donor liver transplantation. Cardiac arrest occurred during the anhepatic phase. After cardiopulmonary resuscitation, spontaneous circulation returned, but the bispectral index level remained below 10 until the end of surgery.

DIAGNOSES

Neurological injury caused by global cerebral hypoperfusion was suspected.

INTERVENTIONS

The patient was treated with mild therapeutic hypothermia for 24hours after resuscitation targeting a core body temperature of 34°C with surface cooling using ice bags.

OUTCOMES

The patient recovered consciousness about 22 hours after the event. However, she showed symptoms of delirium even when discharged. At the 3-month follow-up exam, she showed no specific neurological complications. The transplanted liver showed no problems with regeneration.

LESSONS

Mild therapeutic hypothermia may be safely adopted in cases of cardiac arrest in liver transplant patients and is beneficial for neurological recovery.

International survey of neurosurgical anesthesia (iSonata) : An international survey of current practices in neurosurgical anesthesia

BACKGROUND

No standardized recommendations have been currently defined for anesthesia management of patients undergoing elective intracranial surgery. It can therefore be assumed that international clinical institutions have diverging approaches or standard operating procedures (SOP) which determine the type of general anesthesia, hemodynamic management, neuromuscular blockade, implementation of hypothermia and postoperative patient care.

OBJECTIVE

This international survey aimed to assess perioperative patient management during elective intracranial procedures. This survey was performed from February to October 2018 and 311 neurosurgical, maximum care centers across 19 European countries were contacted. The aim was to evaluate the anesthesia management to provide relevant data of neuroanesthesia practices across European centers. The survey differentiated between vascular and non-vascular as well as supratentorial and infratentorial procedures.

RESULTS

A total of 109 (35.0%) completed questionnaires from 15 European countries were analyzed. The results illustrated that total intravenous anesthesia was most commonly implemented during elective intracranial procedures (83.8%). All centers performed endotracheal intubation prior to major intracranial surgery (100%). Central venous lines were placed in 63.3% of cases. Moderate intraoperative hypothermia was carried out in 12.8% of the procedures, especially during vascular supratentorial and infratentorial surgery. A neuromuscular blockade during surgery was implemented in 74.1% of patients. Assessment of the neuromuscular junction was performed in 59.2% of cases, 76.7% of patients were immediately extubated in the operating room. 84.7% of these patients were directly transferred to a monitoring ward or an intensive care unit (ICU) and 55.1% of ventilated patients were transferred directly to an ICU.

CONCLUSION

The data demonstrate that many aspects of anesthesia management during elective intracranial surgery vary between European institutions. The data also suggest that a broad consensus exists regarding the implementation of total intravenous anesthesia, airway management (endotracheal intubation), the implementation of urinary catheters, large bore peripheral venous lines and the broad availability of cross-matched red blood cell concentrates. Nevertheless, anesthesia management (e.g. central venous catheterization, moderate hypothermia, neuromuscular monitoring) is still handled differently across many European institutions. A lack of standardized guidelines defining anesthetic management in patients undergoing intracranial procedures could explain this variability. Further studies could help establish optimal anesthesia management for these patients. This in turn could help in the development of national and international guidelines and SOPs which could define optimal management strategies for intracranial procedures.

Nonobstetric Surgery During Pregnancy

One percent to 2% of pregnant women undergo nonobstetric surgery during pregnancy. Historically, there has been a reluctance to operate on pregnant women based on concerns for teratogenesis, pregnancy loss, or preterm birth. However, a careful review of published data suggests four major flaws affecting much of the available literature. Many studies contain outcomes data from past years in which diagnostic testing, surgical technique, and perioperative maternal-fetal care were so different from current experience as to make these data of limited utility today. This issue is further compounded by a tendency to combine experience from vastly disparate types of surgery into a single report. In addition, reports in nonobstetric journals often focus on maternal outcomes and contain insufficient detail regarding perinatal outcomes to allow distinction between complications associated with surgical disease and those attributable to surgery itself. Finally, most series are either uncontrolled or use the general population of pregnant women as controls rather than women with surgical disease who are managed nonsurgically. Consideration of these factors as well as our own extensive experience suggests that when the risks of maternal hypotension or hypoxia are minimal, or can be adequately mitigated, indicated surgery during any trimester does not appear to subject either the mother or fetus to risks significantly beyond those associated with the disease itself or the complications of surgery in nonpregnant individuals. In some cases, reluctance to operate during pregnancy becomes a self-fulfilling prophecy in which delay in surgery contributes to adverse perinatal outcomes traditionally attributed to surgery itself.

Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a worldwide health burden with high fatality and permanent disability rates. The overall prognosis depends on the volume of the initial bleed, rebleeding, and degree of delayed cerebral ischemia (DCI). Cardiac manifestations and neurogenic pulmonary edema indicate the severity of SAH. The International Subarachnoid Aneurysm Trial (ISAT) reported a favorable neurological outcome with the endovascular coiling procedure compared with surgical clipping at the end of 1 year. The ISAT trial recruits were primarily neurologically good grade patients with smaller anterior circulation aneurysms, and therefore the results cannot be reliably extrapolated to larger aneurysms, posterior circulation aneurysms, patients presenting with complex aneurysm morphology, and poor neurological grades. The role of hypothermia is not proven to be neuroprotective according to a large randomized controlled trial, Intraoperative Hypothermia for Aneurysms Surgery Trial (IHAST II), which recruited patients with good neurological grades. Patients in this trial were subjected to slow cooling and inadequate cooling time and were rewarmed rapidly. This methodology would have reduced the beneficial effects of hypothermia. Adenosine is found to be beneficial for transient induced hypotension in 2 retrospective analyses, without increasing the risk for cardiac and neurological morbidity. The neurological benefit of pharmacological neuroprotection and neuromonitoring is not proven in patients undergoing clipping of aneurysms. DCI is an important cause of morbidity and mortality following SAH, and the pathophysiology is likely multifactorial and not yet understood. At present, oral nimodipine has an established role in the management of DCI, along with maintenance of euvolemia and induced hypertension. Following SAH, hypernatremia, although less common than hyponatremia, is a predictor of poor neurological outcome.

Extracorporeal membrane oxygenation for cardiac arrest during moyamoya cerebral revascularization surgery: case report

The authors describe the case of a 51-year-old man with bilateral moyamoya disease and prior strokes who developed an asystolic cardiac arrest while undergoing revascularization surgery under mild hypothermia. The patient was successfully treated with venoarterial (VA) extracorporeal membrane oxygenation (ECMO) after manual cardiopulmonary resuscitation (CPR) was unsuccessful for 45 minutes. ECMO is a cardiopulmonary support system that is indicated for respiratory failure in pediatric and adult patients. It is increasingly being used as an extension to mechanical CPR for patients who have suffered cardiac arrest if the underlying cause of cardiac arrest is thought to be reversible. Identifying which patients should be placed on emergency ECMO after cardiac arrest is controversial given its high morbidity and mortality. ECMO in neurosurgical settings has associated risks of intracranial hemorrhage and neurological compromise, while resource utilization is paramount given the high costs of this treatment. This paper is significant because it describes the use of ECMO in an unindicated setting. Limited data are available for ECMO usage after cardiac arrest with baseline cerebral ischemia. Furthermore, this paper raises important considerations for extracorporeal CPR use in a patient who had recently undergone craniotomy. The patient in this report remained on ECMO for 48 hours, after which he was successfully weaned. He developed a pericardial effusion and compartment syndrome from the ECMO but made a complete neurological recovery. Use of ECMO emergently in an appropriately chosen neurosurgical patient is safe, even in the setting of baseline cerebral ischemia and recent craniotomy.

Surgical outcome of primary clipping for anterior circulation aneurysms of size 2 centimeters or larger

BACKGROUND

Aneurysms of the anterior circulation larger than 2cm have a complex relationship to the anterior skull base, requiring a multi-modality management approach. This retrospective study of 54 patients with such aneurysms who underwent clipping between 2001 and 2012 analyzes clinical and surgical data, aneurysm characteristics and correlates them with respect to the Glasgow outcome score at follow-up and immediate post-operative clinical status.

METHODS

Patients with an outcome score of 5 or 4 were categorized as "good", while those with score 3-1 were "poor". Fisher's exact test and paired T-test (p<0.5) were used to test statistical significance for discrete and continuous variables respectively.

RESULTS

44 (81.4%) patients had a good outcome. Patients with non-ophthalmic/paraclinoid aneurysms had significantly lower incidence of adverse intra-operative events (p=0.035). Patients older than 50 years (p=0.045), with adverse intra-operative events (p=0.015) and post-operative infarction (p<0.001) had a poor outcome compared to those younger than 50 years age and those without adverse intra-operative events or infarctions. The grouped age variable had maximum influence on patient outcome. Location and size of aneurysm did not have an overall impact on surgical outcome. There were 4 mortalities.

CONCLUSIONS

Primary clipping of proximal non-cavernous aneurysms on the internal carotid artery is associated with adverse intra-operative events. A multi-modality treatment approach in these aneurysms should be individualized, more so in patients older than 50 years.

Pre, intra and post-ischemic hypothermic neuroprotection in temporary focal cerebral ischemia in rats: morphometric analysis

OBJECTIVE

To evaluate the neuroprotection of mild hypothermia, applied in different moments, in temporary focal cerebral ischemia in rats.

METHODS

Rats was divided into Control (C), Sham (S), Ischemic-control(IC), Pre-ischemic Hypothermia (IH1), Intra-ischemic Hypothermia (IH2), and Post-ischemic Hypothermia (IH3) groups. Morphometry was performed using the KS400 software (Carl Zeiss®) in coronal sections stained by Luxol Fast Blue. Ischemic areas and volumes were obtained.

RESULTS

Statistically, blue areas showed difference for C vs. IC, IC vs. IH1 and IC vs. IH2 (p=0.0001; p=0.01; p=0.03), and no difference between C vs. S, IC vs. IH3 and IH vs. IH2 (p=0.39; p=0.85; p=0.63). Red areas showed difference between C vs. IC, IC vs. IH1 and IC vs. IH2 (p=0.0001; p=0.009; p=0.03), and no difference between C vs. S, IC vs. IH3 and IH1 vs. IH2 (p=0.48; p=0.27; p=0.68). Average ischemic areas and ischemic volumes showed difference between IC vs. IH1 and IC vs. IH2 (p=0.0001 and p=0.0011), and no difference between IC vs. IH3 and IH1 vs. IH2 (p=0.57; p=0.79).

CONCLUSION

Pre-ischemic and intra-ischemic hypothermia were shown to be similarly neuroprotective, but this was not true for post-ischemic hypothermia.

The Use of Hypothermia Therapy in Traumatic Ischemic / Reperfusional Brain Injury: Review of the Literatures

Therapeutic mild hypothermia has been used widely in brain injury. It has evaluated in numerous clinical trials, and there is strong evidence for the use of hypothermia in treating patients with several types of ischemic / reperfusional (I/R) injuries, examples being cardiac arrest and neonatal hypoxic-ischemic encephalopathy.In spite of many basic research projects demonstrating effectiveness, therapeutic hypothermia has not been proven effective for the heterogeneous group of traumatic brain injury patients in multicenter clinical trials. In the latest clinical trial, however, researchers were able to demonstrate the significant beneficial effects of hypothermia in one specific group; patients with mass evacuated lesions. This suggested that mild therapeutic hypothermia might be effective for I/R related traumatic brain injury.In this article we have reviewed much of the previous literature concerning the mechanisms of I/R injury to the protective effects of mild therapeutic hypothermia.

An activation-specific platelet inhibitor that can be turned on/off by medically used hypothermia

OBJECTIVE

Therapeutic hypothermia is successfully used, for example, in cardiac surgery to protect organs from ischemia. Cardiosurgical procedures, especially in combination with extracorporeal circulation, and hypothermia itself are potentially prothrombotic. Despite the obvious need, the long half-life of antiplatelet drugs and thus the risk of postoperative bleedings have restricted their use in cardiac surgery. We describe here the design and testing of a unique recombinant hypothermia-controlled antiplatelet fusion protein with the aim of providing increased safety of hypothermia, as well as cardiac surgery.

METHODS AND RESULTS

An elastin-mimetic polypeptide was fused to an activation-specific glycoprotein (GP) IIb/IIIa-blocking single-chain antibody. In silico modeling illustrated the sterical hindrance of a β-spiral conformation of elastin-mimetic polypeptide preventing the single-chain antibody from inhibiting GPIIb/IIIa at 37°C. Circular dichroism spectra demonstrated reverse temperature transition, and flow cytometry showed binding to and blocking of GPIIb/IIIa at hypothermic body temperature (≤32°C) but not at normal body temperature. In vivo thrombosis in mice was selectively inhibited at hypothermia but not at 37°C.

CONCLUSIONS

This is the first description of a broadly applicable pharmacological strategy by which the activity of a potential drug can be controlled by temperature. In particular, this drug steerability may provide substantial benefits for antiplatelet therapy.