Unexpected fatal neurological deterioration after successful cardio-pulmonary resuscitation and therapeutic hypothermia

Emergent Management of Hypoxic-Ischemic Brain Injury

OBJECTIVE

This article outlines interventions used to improve outcomes for patients with hypoxic-ischemic brain injury after cardiac arrest.

LATEST DEVELOPMENTS

Emergent management of patients after cardiac arrest requires prevention and treatment of primary and secondary brain injury. Primary brain injury is minimized by excellent initial resuscitative efforts. Secondary brain injury prevention requires the detection and correction of many pathophysiologic processes that may develop in the hours to days after the initial arrest. Key physiologic parameters important to secondary brain injury prevention include optimization of mean arterial pressure, cerebral perfusion, oxygenation and ventilation, intracranial pressure, temperature, and cortical hyperexcitability. This article outlines recent data regarding the treatment and prevention of secondary brain injury. Different patients likely benefit from different treatment strategies, so an individualized approach to treatment and prevention of secondary brain injury is advisable. Clinicians must use multimodal sources of data to prognosticate outcomes after cardiac arrest while recognizing that all prognostic tools have shortcomings.

ESSENTIAL POINTS

Neurologists should be involved in the postarrest care of patients with hypoxic-ischemic brain injury to improve their outcomes. Postarrest care requires nuanced and patient-centered approaches to the prevention and treatment of primary and secondary brain injury and neuroprognostication.

Brain injury after cardiac arrest: pathophysiology, treatment, and prognosis

Post-cardiac arrest brain injury (PCABI) is caused by initial ischaemia and subsequent reperfusion of the brain following resuscitation. In those who are admitted to intensive care unit after cardiac arrest, PCABI manifests as coma, and is the main cause of mortality and long-term disability. This review describes the mechanisms of PCABI, its treatment options, its outcomes, and the suggested strategies for outcome prediction.

Cerebral Edema After Cardiopulmonary Resuscitation: A Therapeutic Target Following Cardiac Arrest?

We sought to review the role that cerebral edema plays in neurologic outcome following cardiac arrest, to understand whether cerebral edema might be an appropriate therapeutic target for neuroprotection in patients who survive cardiopulmonary resuscitation. Articles indexed in PubMed and written in English. Following cardiac arrest, cerebral edema is a cardinal feature of brain injury and is a powerful prognosticator of neurologic outcome. Like other conditions characterized by cerebral ischemia/reperfusion, neuroprotection after cardiac arrest has proven to be difficult to achieve. Neuroprotection after cardiac arrest generally has focused on protecting neurons, not the microvascular endothelium or blood-brain barrier. Limited preclinical data suggest that strategies to reduce cerebral edema may improve neurologic outcome. Ongoing research will be necessary to determine whether targeting cerebral edema will improve patient outcomes after cardiac arrest.

The rate of brain death and organ donation in patients resuscitated from cardiac arrest: a systematic review and meta-analysis

BACKGROUND

The occurrence of brain death in patients with hypoxic-ischaemic brain injury after resuscitation from cardiac arrest creates opportunities for organ donation. However, its prevalence is currently unknown.

METHODS

Systematic review. MEDLINE via PubMed, ISI Web of Science and the Cochrane Database of Systematic Reviews were searched for eligible studies (2002-2016). The prevalence of brain death in adult patients resuscitated from cardiac arrest and the rate of organ donation among brain dead patients were summarised using a random effect model with double-arcsine transformation. The quality of evidence (QOE) was evaluated according to the GRADE guidelines.

RESULTS

26 studies [16 on conventional cardiopulmonary resuscitation (c-CPR), 10 on extracorporeal CPR (e-CPR)] included a total of 23,388 patients, 1830 of whom developed brain death at a mean time of 3.2 ± 0.4 days after recovery of circulation. The overall prevalence of brain death among patients who died before hospital discharge was 12.6 [10.2-15.2] %. Prevalence was significantly higher in e-CPR vs. c-CPR patients (27.9 [19.7-36.6] vs. 8.3 [6.5-10.4] %; p < 0.0001). The overall rate of organ donation among brain dead patients was 41.8 [20.2-51.0] % (9/26 studies, 1264 patients; range 0-100 %). The QOE was very low for both outcomes.

CONCLUSIONS

In patients with hypoxic-ischaemic brain injury following CPR, more than 10 % of deaths were due to brain death. More than 40 % of brain-dead patients could donate organs. Patients who are unconscious after resuscitation from cardiac arrest, especially when resuscitated using e-CPR, should be carefully screened for signs of brain death.

Optic nerve sheath diameter as a marker for evaluation and prognostication of intracranial pressure in Indian patients: An observational study

BACKGROUND AND AIMS

The aim was to evaluate efficacy of optic nerve sheath diameter (ONSD) by ultrasound as a noninvasive method for detecting raised intracranial pressure (ICP) in intensive care unit, to compare with computed tomography/magnetic resonance imaging (MRI) findings of raised ICP and to prognosticate ONSD value with treatment.

MATERIALS AND METHODS

We conducted a prospective, observational study on 101 adults by including 41 healthy individuals in group A as control and 60 patients in group B admitted with fever, headache, vomiting, and altered sensorium. We examined them in supine position using 10 MHz linear array probe on closed eyelid. ONSD was measured 3 mm behind the globe in each eye. A mean binocular ONSD > 4.6 mm in female and 4.8 mm in male was considered abnormal. Midline shift, edema, effacement or ONSD > 5.0 mm on T2 MRI suggestive of elevated ICP was used to evaluate ONSD accuracy.

RESULTS

Group A mean ONSD was 4.6 mm in females and 4.8 mm in males. Group B mean ONSD for 17 females was 5.103 ± 0.6221 mm (P = 0.002) and for 43 males 5.081 ± 0.5799 mm (P = 0.032). Radiological sign of raised ICP was confirmed in 35 patients (females = 11 and males = 24) with high ONSD value. Sensitivity of detecting raised ICP by ONSD was 84.6% in females and 75% in males while specificity was 100% in both genders. Out of 25 patients without radiological signs of raised ICP 10 patients showed high ONSD (females = 4.735 mm and males = 4.907 mm). ONSD was well prognosticated with treatment modalities.

CONCLUSION

Bedside ocular ultrasonography for measuring ONSD can be used an early test for diagnosing raised ICP as it is a noninvasive, cost effective bedside test, which can be repeated for re-evaluation.

Noninvasive surrogates of intracranial pressure: another piece added with magnetic resonance imaging of the cerebrospinal fluid thickness surrounding the optic nerve

Optic nerve sheath diameter enlargement measured by ultrasound is known to be associated with raised intracranial pressure (ICP). Magnetic resonance imaging (MRI) of the cerebrospinal fluid (CSF) surrounding the optic nerve has been found, in an elegant study published in Critical Care, to correlate well with lumbar CSF opening pressure, confirming previously published studies. A simple and rapid T2-weighted fat-suppressed sequence was used to noninvasively measure the CSF width surrounding the optic nerve, allowing one to predict lumbar CSF pressure with relatively good performances, taking into consideration the body mass index and the mean arterial blood pressure. Based on these results and when brain MRI is indicated in situations at risk for increased ICP, the optic CSF thickness measurement could be systematically performed and used as a surrogate marker of raised ICP.

[Non-invasive evaluation of intracranial pressure: how and for whom?]

The invasive monitoring of intracranial pressure is useful in circumstances associated with high-risk of raised intracranial pressure. However the placement of intracranial probe is not always possible and non-invasive assessment of intracranial pressure may be useful, particularly in case of emergencies. Transcranial Doppler measurements allow the estimation of perfusion pressure with the pulsatility index. Recently, new ultrasonographic methods of cerebral monitoring have been developed: the diameter of the optic nerve sheath diameter, a surrogate marker of raised intracranial pressure and the estimation of median shift line deviation.

Therapeutic hypothermia for out-of-hospital cardiac arrest: an update for neurosurgeons

BACKGROUND

Neurosurgeons have been familiar with the idea that hypothermia is protective against various types of brain injuries, including traumatic brain injury (TBI). Recent randomized controlled trials, however, have failed to demonstrate the efficacy of therapeutic hypothermia (TH) in patients with TBI. On the other hand, TH becomes popular in the treatment of out-of-hospital cardiac arrest (OHCA) survivors, after randomized controlled trials have shown that survival rate and functional outcome is improved with the use of TH in selected patients. We believe that knowledge on the recent progress in TH for OHCA is useful for neurosurgeons, because feedback of information obtained in the treatment of OHCA may revitalize the interest in TH for neurosurgical disorders, particularly TBI.

METHODS

A review of the literature was conducted with the use of PubMed.

RESULTS

Various cooling techniques and devices have been developed and trialed in the treatment of OHCA survivors, including prehospital cooling with bolus ice-cold saline, endovascular cooling catheters, and new generation surface cooling devices, some of which have already been known to neurosurgeons. The efficacy of these new methods and devices has been demonstrated in many preliminary studies, and phase III trials are also expected.

CONCLUSIONS

Neurosurgeons and critical care medicine physicians pursue the same goal of rescuing the brain from the secondary injury despite the difference in etiology (focal trauma vs. global ischemia), with the presumption that earlier and faster implementation of TH will result in better outcome. Thoughtful application of knowledge and techniques obtained in OHCA to TBI under a rigorously controlled situation will make a small, but significant difference in the outcome of TBI victims.

Therapeutic hypothermia

Pioneer works on therapeutic hypothermia (TH) half a century ago already showed promising results but clinical application was limited by a lack of understanding of the underlying pathophysiology, lack of reliable method for temperature control and lack of intensive care facilities to deal with possible complications. More recently, 2 studies in 2002 supported the application of moderate TH (32.0-34.0℃) in post-cardiac arrest patients. Although the studies included only patients suffering from out-of-hospital VF, many ICUs world-wide are applying the therapy to all post-cardiac arrest patients irrespective of site or presenting rhythm. While primary coagulopathy and cardiogenic shock are usually stated as relative contraindications, evidences are accumulating to support the application of TH in patients with cardiogenic shock. TH can be divided into 4 phases: Induction, maintenance, de-cooling and normothermia. Induction is usually achieved by infusion of cold isotonic fluid. The precautions included avoidance of over-cooling, hypokalaemia, hyperglycaemia, and shivering. TH can be maintained by many different methods, varying in their level of invasiveness, cost and effectiveness. Issues including changes in pharmacokinetics and haemodynamics, and susceptibility to infection need to the addressed. The optimal duration of maintenance is unknown but the usual practice is 12-24 hours. De-cooling and rewarming is especially challenging because complications can be serious if temperature rise by more than 1℃ every 3-5 hours. Life-theatening hyperkalaemia can occur especially if patient suffers from renal insufficiency. Fever is a frequent complication either due to infection or post-cardiac arrest syndrome but patient must be kept normothermic for 72 hours.

Methods of cooling: practical aspects of therapeutic temperature management

OBJECTIVES

To review traditional and newer means of inducing, maintaining, and withdrawing therapeutic hypothermia and normothermia. To suggest treatment algorithms for temperature modulation and review neuromonitoring options.

DESIGN

A review of current literature describing methods of performing therapeutic temperature management and neuromonitoring during the cooling, maintenance, and decooling periods. Algorithms for performing therapeutic temperature management are suggested.

RESULTS

Temperature management can be safely and effectively performed using traditional or newer modalities. Although traditional means of cooling are feasible and efficacious, modern devices utilizing feedback loops to maintain steady body temperature and prevent overcooling have advantages in ease of application, patient safety, maintenance of target temperature, and control of decooling. Neuromonitoring options should be adapted to an individual patient and situation.

CONCLUSIONS

Intensivists should be familiar with techniques to induce, maintain, and withdraw therapeutic temperature management, and select the most appropriate method for a given patient and situation.

Use of T2-weighted magnetic resonance imaging of the optic nerve sheath to detect raised intracranial pressure

Introduction

The dural sheath surrounding the optic nerve communicates with the subarachnoid space, and distends when intracranial pressure is elevated. Magnetic resonance imaging (MRI) is often performed in patients at risk for raised intracranial pressure (ICP) and can be used to measure precisely the diameter of optic nerve and its sheath. The objective of this study was to assess the relationship between optic nerve sheath diameter (ONSD), as measured using MRI, and ICP.

Methods

We conducted a retrospective blinded analysis of brain MRI images in a prospective cohort of 38 patients requiring ICP monitoring after severe traumatic brain injury (TBI), and in 36 healthy volunteers. ONSD was measured on T2-weighted turbo spin-echo fat-suppressed sequence obtained at 3 Tesla MRI. ICP was measured invasively during the MRI scan via a parenchymal sensor in the TBI patients.

Results

Measurement of ONSD was possible in 95% of cases. The ONSD was significantly greater in TBI patients with raised ICP (>20 mmHg; 6.31 ± 0.50 mm, 19 measures) than in those with ICP of 20 mmHg or less (5.29 ± 0.48 mm, 26 measures; P < 0.0001) or in healthy volunteers (5.08 ± 0.52 mm; P < 0.0001). There was a significant relationship between ONSD and ICP (r = 0.71, P < 0.0001). Enlarged ONSD was a robust predictor of raised ICP (area under the receiver operating characteristic curve = 0.94), with a best cut-off of 5.82 mm, corresponding to a negative predictive value of 92%, and to a value of 100% when ONSD was less than 5.30 mm.

Conclusions

When brain MRI is indicated, ONSD measurement on images obtained using routine sequences can provide a quantitative estimate of the likelihood of significant intracranial hypertension.