Changes in intracranial pressure associated with apneumic retractors
J. R. Este-McDonald, L. G. Josephs, D. H. Birkett and E. F. Hirsch
Department of Surgery, Boston University Medical Center, Mass, USA.
OBJECTIVE: To investigate the effect of apneumic retraction on intracranial
pressure (ICP) using a live porcine model. DESIGN: Five 25- to 30-kg pigs
had a fiber-optic ICP bolt inserted under general endotracheal anesthesia
and were monitored for ICP, mean arterial pressure, arterial blood gas
measurements, and intra-abdominal pressure before, during, and after
pneumoperitoneum, with each period 30 minutes long. These series of
measurements were repeated after artificially raising ICP with an epidural
balloon to create a head-injured model. The mean (+/- SE) ICP in the
noninjured model at baseline was 13.46 +/- 1.01 mm Hg; during
pneumoperitoneum, 18.72 +/- 1.50 mm Hg (P = .0001). Similarly, in the
head-injured model, ICP was raised artificially to a new baseline of 22 +/-
1.75 mm Hg with an epidural balloon, and pneumoperitoneum increased ICP to
27.40 +/- 0.93 mm Hg (P = .0001). Pneumoperitoneum was then released, and
an apneumic retractor was inserted while maintaining the inflated epidural
balloon. MAIN OUTCOME MEASURE: Changes in ICP. RESULTS: Applying anterior
wall retraction equivalent to 20 mm Hg was not associated with changes in
ICP. These observations were independent of any changes in arterial PCO2 or
arterial pH. Following the release of pneumoperitoneum, abdominal wall
retraction, and epidural balloon, all measurements reverted to baseline.
CONCLUSION: Pneumoperitoneum adversely affects ICP, while apneumic
retraction may not affect animals with raised ICP. These findings suggest
that pneumoperitoneum should be used with caution in patients with raised
ICP, and apneumic retraction may be a safer alternative for laparoscopic
evaluation in this population.
