Concepts and diagnosis of brain death

Medicine, Technology, and Religion Reconsidered: The Case of Brain Death Definition in Israel

The introduction of respiratory machines in the 1950s may have saved the lives of many, but it also challenged the notion of death itself. This development endowed “machines” with the power to form a unique ontological creature: a live body with a “dead” brain. While technology may be blamed for complicating things in the first place, it is also called on to solve the resulting quandaries. Indeed, it is not the birth of the “brain-dead” that concerns us most, but rather its association with a web of epistemological and ethical considerations, where technology plays a central role. The brain death debate in Israel introduces highly sophisticated religious thought and authoritative medical expertise. At focus are the religious acceptance and rejection of brain death by a technologically savvy group of rabbis whose religious doctrine––along with a particular form of religious reasoning––is used to support the truth claims made from the scientific community (brain death is death) but challenge the ways in which they are made credible (instrumental rather than clinical). In our case, brain death as “true” death is made religiously viable with the very use of technological apparatus and scientific rhetoric that stand at the heart of the scientific ethos.

False-Positive Diagnosis of Brain Death Following the Pediatric Guidelines: Case Report and Discussion

A 2-year-old boy with severe head trauma was diagnosed brain dead according to the 2011 Pediatric Guidelines. Computed tomographic (CT) scan showed massive cerebral edema with herniation. Intracranial pressures were extremely high, with cerebral perfusion pressures around 0 for several hours. An apnea test was initially contraindicated; later, one had to be terminated due to oxygen desaturation when the Pco₂ had risen to 57.9 mm Hg. An electroencephalogram (EEG) was probably isoelectric but formally interpreted as equivocal. Tc-99m diethylene-triamine-pentaacetate (DTPA) scintigraphy showed no intracranial blood flow, so brain death was declared. Parents declined organ donation. A few minutes after withdrawal of support, the boy began to breathe spontaneously, so the ventilator was immediately reconnected and the death declaration rescinded. Two hours later, life support was again removed, this time for prognostic reasons; he did not breathe, and death was declared on circulatory-respiratory grounds. Implications regarding the specificity of the guidelines are discussed.

Revised CT angiography venous score with consideration of infratentorial circulation value for diagnosing brain death

BACKGROUND

Computed tomography angiography (CTA) is largely performed in European countries as an ancillary test for diagnosing brain death. However, CTA suffers from a lack of sensitivity, especially in patients who have previously undergone decompressive craniectomy. The aim of this study was to assess the performance of a revised four-point venous CTA score, including non-opacification of the infratentorial venous circulation, for diagnosing brain death.

METHODS

A preliminary study of 43 control patients with normal CTAs confirmed that the infratentorial superior petrosal vein (SPV) was consistently visible. Therefore, 76 patients (including ten with decompressive craniectomy) who were investigated with 83 CTAs to confirm clinical brain death were consecutively enrolled between July 2011 and July 2013 at a university centre. The image analysis consisted of recording non-opacification of the cortical segment of the middle cerebral artery and internal cerebral vein (ICV), which were used as the reference CTA score, as well as non-opacification of the SPV. The diagnostic performance of the revised four-point venous CTA score based on the non-opacification of both the ICV and SPV was assessed and compared with that of the reference CTA score.

RESULTS

The revised four-point venous CTA score showed a sensitivity of 95 % for confirming clinical brain death versus a sensitivity of 88 % with the reference CTA score. Non-opacification of the SPV was observed in 95 % of the patients. In the decompressive craniectomy group, the revised four-point CTA score showed a sensitivity of 100 % compared with a sensitivity of 80 % using the reference CTA score.

CONCLUSION

Compared with the reference CTA score, the revised four-point venous CTA score based on ICV and SPV non-opacification showed superior diagnostic performance for confirming brain death, including for patients with decompressive craniectomy.

Apnea testing for the diagnosis of brain death

OBJECTIVES

A review is given on various methods, preconditions and pitfalls of apnea testing for the diagnosis of brain death.

MATERIALS AND METHODS

An extensive medical data base search was implemented by information gathered from books and our own experience with more than 2000 apnea tests.

RESULTS

While testing for apnea (AT) is considered indispensable worldwide, recommendations and handling differ. Rather than relying on elapsed time, a specific target value for the partial arterial pressure of carbon dioxide (PaCO2) should be aimed at being the maximum physiological stimulus for respiration. Methodological points are elaborated upon in detail for apneic oxygenation and hypoventilation.

CONCLUSION

AT is an indispensable element of diagnosing brain death. Although with proper handling and adequate precautions AT is safe, it should be performed as a last resort. An international agreement on target values for the PaCO2 is desirable.

Fast, Simple, and Validated Gas Chromatographic-Mass Spectrometric Assay for Quantification of Drugs Relevant to Diagnosis of Brain Death in Human Blood Plasma Samples

In addition to total anamnesis, one of the important aspects in diagnosis of brain death is the exclusion of effective plasma concentrations of drugs that might mimic brain death. A minimum consensus for toxicological analysis in this context includes relevant analytes (thiopental, pentobarbital, methohexital, phenobarbital, diazepam, nordazepam, and midazolam) and proposes limits of quantification. Propofol is another relevant drug. After liquid-liquid extraction of 200 microL of plasma using 50 microL of a solution of deuterated internal standards in butyl acetate and 50 microL of butyl acetate, 2 microL of the organic phase was analyzed by gas chromatography-mass spectrometry using selected-ion monitoring mode. Validation included the parameters selectivity, calibration model, precision and accuracy, and extraction efficiency. Accuracy and precision data obtained using 6-point and 1-point calibration were compared. The abovementioned analytes were separated within 10 minutes and sensitively detected. No interfering peaks were observed in blank samples from 10 different sources. The linearity ranges were 0.5-6 mg/L for propofol, 0.25-10 mg/L for pentobarbital and thiopental, 0.125-10 mg/L for methohexital, 2.5-50 mg/L for phenobarbital, 0.05-2.5 mg/L for diazepam and nordazepam, and 0.01-0.5 mg/L for midazolam. Extraction efficiency ranged from 85% to 111%. The acceptance criterion for accuracy and precision (99% confidence interval of measured mean within +/-50% of target value) was fulfilled for all analytes, even with 1-point calibration using a calibrator close to the center of the linearity range. The assay was applied to analysis of real brain death cases. In conclusion, the described assay allowed fast and reliable determination of analytes relevant to diagnosis of brain death, and 1-point calibration kept the workload low.

Difficulty in brainstem death testing in the presence of high spinal cord injury

In the UK, when the standard brain death criteria are met, further investigations are not necessary. Confirmatory tests can be useful, however, when it is not possible to carry out all of the brainstem tests. We report the case of a patient with multiple trauma and a high spinal cord injury who was apnoeic. Confirmatory tests (EEG, brainstem, auditory evoked potential) were essential in supporting the diagnosis of brainstem death to allow withdrawal of artificial ventilation, as organ donation was being considered.

Automated procedure for determination of barbiturates in serum using the combined system of PrepStation and gas chromatography-mass spectrometry

A system of an automatic sample preparation procedure followed by on-line injection of the sample extract into a gas chromatograph-mass spectrometer (GC-MS) was developed for the simultaneous analysis of seven barbiturates in human serum. A sample clean-up was performed by a solid-phase extraction (SPE) on a C18 disposable cartridge. A SPE cartridge was preconditioned with methanol and 0.1 M phosphate buffer. After loading 1.5 ml of a diluted serum sample into the SPE cartridge, the cartridge was washed with 2.5 ml of methanol-water (1:9, v/v). Barbiturates were eluted with 1.0 ml of chloroform-isopropanol (3:1, v/v) from the cartridge. The eluate (1 microl) was injected into the GC-MS. The calibration curves, using an internal standard method, demonstrated a good linearity throughout the concentration range from 0.1 to 10 microg ml(-1) for all barbiturates extracted. The proposed method was applied to 27 clinical serum samples from three patients who were administrated secobarbital.