Asymmetry of Bispectral Index (BIS) in severe brain-injured patients treated by barbiturates with unilateral or diffuse brain injury.

OBJECTIVE: Bispectral index (BIS) may be used in traumatic brain-injured patients (TBI) with intractable intracranial hypertension to adjust barbiturate infusion but it is obtained through a unilateral frontal electrode. The objective of this study was to evaluate differences in BIS between hemispheres in two groups: unilateral frontal (UFI) and diffuse (DI) injured. PATIENTS AND METHODS: Prospective monocenter observational study in 24 TBI treated with barbiturates: 13 UFI and 11 DI. Simultaneous BIS and EEG was recorded for 1h. Goal of monitoring was a left BIS between 5 and 15. Biases in BIS were considered as clinically relevant if greater than 5. Differences in biases were interpreted from both statistical (Mann-Whitney test) and clinical points of view. RESULTS: Mean BIS in the two hemispheres remained in the same monitoring range. There were statistic and clinical differences in some values in the two groups of patients (15% of bias greater than I5I in UFI group and 10% in DI group). BIS monitoring allowed the adequate number of bursts/minutes to be predicted in 18 patients and did not detect an overdosage in 2. CONCLUSIONS: While asymmetric BIS values in TBI patients occur whatever the kind of injury, they were not found to be clinically relevant in most of these heavily sedated patients. Asymmetrical BIS monitoring might be sufficient to monitor barbiturate infusion in TBI provided that the concordance between BIS and EEG is regularly checked.

[Traumatic rupture of the aortic isthmus in a patient with severe head injury]. / Rupture traumatique de l'isthme aortique chez un traumatisé crânien grave.

A 32-year-old man sustained a severe head injury in a road traffic accident. On admission, he was in deep coma (6 on the Glasgow coma scale). The aortic knuckle was difficult to identify on a plain chest film. Twenty hours after admission, the aortic knuckle had completely disappeared and the mediastinal shadow had become enlarged. The diagnosis of a ruptured aortic isthmus was confirmed by angiography. Surgical repair of this lesion may be carried out either with simple aortic cross-clamping, or by using cardiopulmonary bypass (CPB). Either technique may worsen other injuries, especially head injury, by initiating severe arterial hypertension or coagulation disturbances. In this patient, the technique chosen was aortic cross-clamping with permanent monitoring of the intracranial and cerebral perfusion pressures. Anaesthesia was obtained with 5 mg.kg-1 of thiopentone, 30 mg.kg-1 x h-1 of sodium gamma hydroxybutyrate and 8 micrograms.kg-1 x h-1 of fentanyl. Surgery lasted for 90 min, with 33 min of aortic clamping. The increase in arterial blood pressure was controlled with 0.25 mg.kg-1 x h-1 of thiopentone and nicardipine which was stopped 8 min before unclamping. The postoperative course was uneventful. Sedation was stopped after 8 days, and the patient regained consciousness two days later. These remained a paraplegia with no sensory deficit, which had totally receded 15 months later. Carrying out this emergency surgery without CPB means that the intracranial pressure must imperatively be monitored during surgery. Any intracranial hypertension should delay the surgery.

[Hemodynamic, coagulation and glycoregulation changes induced by brain death]. / Perturbations de l'hémodynamique, de la coagulation et de la glycorégulation induites par la mort cérébrale.

Brain death results in various changes in circulation haemostasis, acid-base balance and glycoregulation. This study was carried out between February 1988 and December 1988 in 91 patients with brain death. Age range was between 6 and 58 years. The cause of brain death was brain trauma (71%) and vascular malformations (26%). In all patients a cardio-vascular collapse occurred at the moment of brain death, requiring an intravascular loading (466.3 +/- 240.3 ml.h-1) with crystalloids and albumin. Dopamine was used in 70% of cases at the dose of 3 micrograms.kg.min-1 to improve kidney and splanchnic perfusion. No alterations of acid-base balance were observed in these patients who admitted for organ donation in a short delay (17.1 +/- 6 h). Haemostasis was modified in all patients but the alterations occurred before the brain death and were related to brain injury. Further investigations are required for a better understanding of glycoregulation changes as they could influence pancreatic transplant survival. Hormonal changes have also to be more extensively studied for possible physiopathologic causes of the variations. A better understanding of these alterations will be of benefit for management of patients in brain death and potential organ donors.

[Rhabdomyolysis after prolonged knee-chest position]. / Rhabdomyolyse après position génu-pectorale prolongée.

Two cases are described of surgery for spondylolisthesis requiring prolonged knee-chest position (5 h 20 min and 4 h 30 min); acute renal failure with anuria occurred early in one case (within the first 24 h postoperatively), and later in the other case (on the 8th day). The diagnosis of rhabdomyolysis was made on the increase of CPK and myoglobin blood levels. Post-haemodialysis evolution was satisfactory. The possible mechanism was muscle compression against the rests. Diagnosis must be made quickly; the only treatment is early fasciotomy, with the supplying of alkali to prevent acute renal failure. It would appear that the knee-chest position can be kept a maximum of 3 h without any problem.