The problems of controlled ventilation in the neurosurgical patient include those common to other patient groups. They include effects on cardiac output, hormonal changes, risks of barotrauma, and the introduction of infection. Additionally, sedation may be required to facilitate mechanical ventilation, and this may prevent neurological assessment.
PEEP is a necessary adjuvant in the treatment of many patients requiring mechanical ventilation for respiratory failure. However, it can have adverse effects on intracranial pressure which may be disadvantageous in neurosurgical patients. Rises in central venous pressure during PEEP may impair cerebral venous return and increase intracranial pressure. The effect of PEEP on intracranial pressure is variable, but is greatest in those with a low intracranial compliance. The intracranial effects of PEEP can be minimized by positioning the patient in a head-up position (15°-30°), with the neck in a moderate degree of flexion, to encourage maximal cerebral venous drainage. PEEP levels of up to 10 to 12 cmH2O have little effect on intracranial pressure under such circumstances. PEEP is also less easily transmitted to the intracranial compartment if the pulmonary compliance is low.
Invasive hemodynamic and intracranial pressure monitoring are necessary in all neurosurgical patients requiring more than modest levels of PEEP. In this way the cerebral perfusion pressure (CPP) can be measured and maintained using the following relationship:
Was this article helpful?