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PubMed1989

[Variability of heart rate as a diagnostic criterion for determining brain death].

Determination of brain death and proof of its irreversibility are necessary when intensive care applied to patients with cerebral areflexia is to be discontinued. In almost all countries a 12-hour observation time with consecutive clinical confirmation of brain death is sufficient to meet the legal needs. If it is possible to get organs for transplantation purposes, a reduction of the observation period is required. Permissible and suitable technical methods for this purpose are reported on. Heart rate variability as a clinical parameter has not yet been sufficiently investigated. Its validity for diagnosing brain death is examined. The beat-to-beat heart interval was measured in 46 patients 68 times and dispersion as well as the coefficient of variability were calculated. In 25 cases the time of investigation was shortly after clinical deterioration and in 27 cases after brain death had been confirmed by a neurologist. Furthermore, 14 and 7 preliminary investigations, respectively, were considered comparatively. It was shown that the significant decrease in heart rate variability was a prognostically bad symptom. Moreover, a fast Fourier transformation was carried out. The most important frequency ranges, marked A, B and C, and their respective percentage were compared. In the course of intensive therapy a remarkable decrease in the B percentage and a simultaneous increase in the C percentage are indicators for bad prognosis.

Brain Death↗

PubMed2003

Functional evidence of reversible ischemic injury immediately after the sympathetic storm associated with experimental brain death.

BACKGROUND: Acute brain death from increased intracranial pressure results in a transient increase in myocardial adenosine and lactate, which indicates that oxygen demand exceeds oxygen delivery during the sympathetic "storm". The aim of this study was to determine the functional significance of this period of ischemia. METHODS: Brain death was inflicted on 40 Westran pigs (36.5-68.0 kg) by inflating a 21-ml subdural balloon over 3 minutes. In 38 animals, micromanometry and sonomicrometry were used to obtain left ventricular pressure-volume loops to determine the preload recruitable stroke work (PRSW) relationship. Data files were recorded before and at 15-minute intervals after beginning balloon inflation. Plasma troponin I was measured before and 60 minutes after beginning balloon inflation in the 38 instrumented and 2 non-instrumented animals. RESULTS: All animals experienced the classical sympathetic storm. The slope of the PRSW relationship decreased, and the volume-axis intercept shifted to the right 15 minutes after beginning balloon inflation (p < 0.0001). Progressive incremental recovery (leftward shift) occurred between subsequent time points (p < or = 0.0018). In the instrumented animals, the mean plasma troponin I level increased from 1.4 +/- 1.6 microg/liter to 2.8 +/- 2.3 microg/liter (p < 0.001). However, troponin I was not detected before or after induction of brain death in the plasma of either non-instrumented animal (p = 0.001). CONCLUSIONS: The sympathetic storm produced transient contractile dysfunction, consistent with ischemic injury. However, troponin I release reflected surgical instrumentation and not brain death.

Animals↗

PubMed1990

[Is brain death actually death?].

The paper rejects "brain death" as a new criterion, or definition, of actual death. The main theses are two: 1. Brain death as such--in any of its meanings--is not man's death and this can be proven by means of many cogent and some plausible arguments. 2. Even if the theoretical arguments against the identification of man's actual death with brain death did not demonstrate their non-identity, the opposite position would still be uncertain, at least. In view of this undeniable fact, a minimal ethical responsibility demands that we must not act, by organ retrievals, on the assumption of the identity of "brain death"--in any of its meanings--with man's actual death. We must avoid those actions which, like killing, presuppose a high degree of moral certainty concerning death, given that we cannot attain such certainty, as in the case of brain death. Thus organ and heart-explantations are found to be unethical. A newly thought out notion of biological death of the human organism as a whole ("clinical death" as irreversible cessation of all vital bodily functions, in particular of cardiopulmonary and cerebral functions) is proposed as theoretically best founded and ethically safest medical criterion of death.

Brain Death↗

PubMed1995

99mTc HM-PAO brain perfusion SPECT in brain death.

Diagnosis of brain death must be certain to allow discontinuation of artificial ventilation and organ transplantation. Brain death is present when all functions of the brain stem have irreversibly ceased. Clinical and electrophysiological criteria may be misinterpreted due to drug intoxication, hypothermia or technical artefacts. Thus, if clinical assessment is suboptimal, reliable early confirmatory tests may be required for demonstrating absence of intracranial blood flow. We have easily carried out and interpreted 99mTc HM-PAO SPECT in a consecutive series of 40 comatose patients with brain damage, without discontinuing therapy. Brain death was diagnosed in 7 patients, by recognising absence of brain perfusion, as shown by no intracranial radionuclide uptake. In patients in whom perfusion was seen on brain scans, HM-PAO SPECT improved assessment of the extent of injury, which in general was larger than suggested by CT.

Adolescent↗

PubMed1975