Cerebral dysfunction in sepsis is common in critically ill adults. However, little is known of the effects of sepsis on cerebral haemodynamics. We studied 12 sedated and ventilated patients in whom sepsis had been established for > 24 h. Transcranial Doppler measurements of the middle cerebral artery flow velocity were made at normocapnia, then hypocapnia ()1 kPa) and hypercapnia (+1 kPa). From these data, cerebrovascular reactivity to carbon dioxide was calculated. Variables indicating disease severity, systemic cardiovascular status and outcome were also recorded. We found significant changes in cerebrovascular reactivity to carbon dioxide. Only three of 12 patients had a cerebrovascular reactivity to carbon dioxide in the normal range; seven patients had a reduced cerebrovascular reactivity to carbon dioxide, whereas in two patients it was raised. In this small sample, we could not find any trend of association between altered cerebrovascular reactivity to carbon dioxide and severity of illness, cardiovascular status or outcome. This study suggests that established sepsis profoundly affects the vascular tone and reactivity, not only of the systemic circulation, but also of the cerebral vasculature.
We measured the effect of 5 and 10 cm H(2)O continuous positive airways pressure (CPAP) on middle cerebral artery blood flow velocity (FV) in 15 awake, healthy volunteers by using transcranial Doppler ultrasonography. Mean, systolic, and diastolic FV plus pulsatility index were recorded. No significant change in any measured variable was observed with the application of 5 or 10 cm H(2)O CPAP. These results are in contrast to those of a previous study, which found a significant increase in mean FV and a decrease in pulsatility index during the application of 12 cm H(2)O CPAP.
This study compares prospectively the cardiovascular and catecholamine responses to central venous and pulmonary artery catheterization before and after induction of general anaesthesia. Twenty patients for elective coronary artery surgery were randomized into two groups. One group had central venous and pulmonary artery catheterization performed awake using local anaesthesia. The other group had these catheters inserted following induction of general anesthaesia. In all patients heart rate, arterial blood pressure, ST segment analysis and epinephrine and norepinephrine
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