Influence of inspiration:expiration ratio on intracranial and cerebral perfusion pressure in acute stroke patients.
OBJECTIVE
We undertook this study to evaluate the influence of the inspiration:expiration (I:E) ratio on intracranial pressure and cerebral perfusion in patients with acute stroke.


METHODS
Ventilated patients with acute stroke were examined under a protocol involving variations of I:E ratio from 1:2 to 1:1 to 1:2 under positive end-expiratory pressure (PEEP) of 5.3 and - subsequently - 10.6 cmH(2)O. Intracranial pressure was monitored with parenchymal or ventricular catheters. Mean arterial blood pressure, intracranial pressure (ICP), heart rate and peak mean flow velocity of the middle cerebral arteries were continuously recorded.


METHODS
Neurological intensive care unit.


METHODS
A total of 45 monitoring sessions were performed in 16 patients (subarachnoid haemorrhage 3, ischemic stroke 13).


RESULTS
No significant changes in any of the parameters monitored were evident in association with the I:E ratio variations under either of the PEEP levels applied. It must be noted, though, that ICP exceeded 15 mmHg in only 5/45 monitoring sessions, and never exceeded 20 mmHg.


CONCLUSIONS
Our preliminary results suggest that variations of the I:E ratio cause no significant changes in intracranial or cerebral perfusion pressure and, thus, can be safely used in patients with acute stroke without intracranial hypertension. The influence of I:E ratio variations on stroke patients with intracranial hypertension remains to be evaluated.
Department of Neurology, University of Heidelberg, Germany. Dimitrios.Georgiadis@nos.usz.ch
Dimitrios
D
Georgiadis
Stefan
S
Schwarz
Rainer
R
Kollmar
Ralf W
RW
Baumgartner
Stefan
S
Schwab
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D011175:Positive-Pressure Respiration; D015656:Respiratory Mechanics; D020521:Stroke / Q000503:physiopathology* / Q000628:therapy