Expansion of an Air-Filled Subdural Space During Nitrous Oxide Anesthesia

Abstract

The long-term administration of nitrous oxide anesthesia during craniotomy as well as following closure of the parietal craniotomy flap (under no tension) leads to significant expansion of the residual air bubble trapped under the dura. A case is presented in which an extracerebral avascular space, filled only with gas, caused a marked shift of the intracranial structures and uncal herniation secondary to nitrous oxide anesthesia during craniotomy and postcraniotomy angiography.

Intraoperative development of tension pneumocephalus in a patient undergoing repair of a cranial-dural defect under nitrous oxide anesthesia

“…[ 9 17 ] Since then, N 2 O has been implicated as a cause of tension pneumocephalus in other case reports. [ 11 12 18 19 ]…”

“…Hence, with increased amount of intracranial gas, there is a severe and rapid increase in intracranial pressure (ICP), especially with a preexisting pneumocephalus. [ 11 12 13 ]…”

Pediatric Pneumoencephalography with Nitrous Oxide

“…The patient of M ali.amo el al. [7] developed subfalcial and uncal herniation following expansion of a surgically trapped intracranial air bubble, and Phillipart [9] showed that NoO anesthesia was especially hazardous when a space-occupying mass Fig. 3.…”

Effects of general anaesthesia on size of cerebrospinal fluid spaces during and after pneumoencephalography.

“…Philippart et al (1968) suggested that the cerebrospinal fluid compartment is 'effectively indistensible', and explained the rise in pressure they observed as a direct result of this. Mallamo et al (1975) described considerable increase in size of a subdural air bubble remaining after a craniotomy while the patient was maintained under anaesthesia with 50% nitrous oxide. Gas embolism via ventriculoatrial shunts was described in two cases having air in the cerebral ventricles by Paul and Efyects of general anaesthesia on size of cerebrospinal fluid spaces Munson (1976); in one of these a cardiac murmur due to the gas in the shunt could be reproduced at will by reintroducing nitrous oxide to the inhaled gases!…”

“…The explanation offered for these observations hinges on the much greater solubility of nitrous oxide as compared with nitrogen (by a factor of 34, according to Mallamo et al (1975)). The contrast medium (air) is effectively 80% nitrogen and 20% oxygen.…”