Cerebral venous sinus pressure in seated dogs: impact of PEEP, cervical venous compression, and abdominal compression

The authors studied the effects of positive end-expiratory pressure (10 cmH2O PEEP), abdominal compression, and neck compression on dural venous sinus pressure (VSP) in seated dogs. Abdominal compression increased the central venous pressure (CVP) as well as both the systemic arterial pressure and the cardiac output and thus may offer a useful substitute for an antigravity suit. Except when CVP was greater than 8 mmHg, there was little or no correlation between CVP and VSP. Moreover, each method increased VSP, but this effect was closely related to VSP prior to application of the method (pre-VSP). On comparing the VSP changes in relation to the pre-VSP levels when they were either above or below -1.0 mmHg, significant differences were noted in VSP increases, i.e., -0.4 +/- 1.3 (mean +/- SEM) and 4.3 +/- 1.2 mmHg by PEEP, 1.9 +/- 0.3 and 6.4 +/- 0.4 mmHg by abdominal compression, and 10.2 +/- 1.3 and 1.5 +/- 0.5 mmHg by neck compression, respectively. This indicates that PEEP and abdominal compression were more effective in increasing relatively highly negative pre-VSP (less than -1.0 mmHg), while neck compression greatly increased pre-VSP when it was at or above a slightly negative pressure (-1.0 mmHg). The authors conclude that a single application of any one of these three methods during sitting-position surgery may not be effective in increasing cerebral dural sinus pressure.