Document Detail

The effects of high-frequency positive-pressure ventilation on intracranial pressure and brain surface movement in cats.
MedLine Citation:
PMID:  7015926     Owner:  NLM     Status:  MEDLINE    
Compared to traditional, low-frequency ventilation (LFV), mechanical ventilation at high frequencies (60-200 breaths/min) and low tidal volumes (HFV) is known to: 1) eliminate respiratory-synchronous variations in blood pressure; 2) minimize ventilatory effects on the cardiovascular system; 3) reduce peak airway pressures; and 4) suppress spontaneous respiratory efforts. Since these and other properties may make HFV useful in patients with acute intracranial pathology, we studied the effects of HFV on intracranial pressure (ICP) in cats. Compared with LFV (rate 11/min, tidal volume equals 15 ml/kg), HFV (rate 100/min, VT equals 3.3 ml/kg) had little effect on mean arterial pressure, heart rate, right atrial pressure, mean ICP or mean cerebral perfusion pressures, even if baseline ICP was raised using an epidural balloon. However, HFV effectively eliminated ventilator-linked fluctuations in both blood pressure and ICP, and at all levels of mean ICP studied (4.8, 15, and 30 torr), significantly reduced the peak ICP seen during a single respiratory cycle. The reduction in ICP fluctuation and peak pressure was more pronounced as intracranial complicance fell. However, the physiologic significance of such a change in the ICP pressure waveform is unknown. Because of the observed influence of HFV on ICP fluctuations, we also examined its effects on the physical movement of the exposed brain, using a non-contact, inductive displacement measuring device. During LFV, the cortical surface moved "in and out" by 0.36 plus or minus 0.1 (plus or minus SD) mm, a distance sufficient to make microscopic focusing difficult. Changing to HFV reduced surface movement to 0.05 plus or minus 0.01 mm, producing a very stable surface. These results suggested that HFV may play a very important role in the intraoperative management oif patients undergoing certain neurosurgical procedures, particularly those requiring microsurgical techniques where reduced brain movement may facilitate surgery.
M M Todd; S M Toutant; H M Shapiro
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Anesthesiology     Volume:  54     ISSN:  0003-3022     ISO Abbreviation:  Anesthesiology     Publication Date:  1981 Jun 
Date Detail:
Created Date:  1981-07-23     Completed Date:  1981-07-23     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  496-504     Citation Subset:  AIM; IM    
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MeSH Terms
Brain / physiology*
Cerebral Cortex / anatomy & histology
Intermittent Positive-Pressure Ventilation*
Intracranial Pressure*
Positive-Pressure Respiration*
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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