TRANSCUTANEOUS CARBON-DIOXIDE MEASUREMENT AFTER CRANIOTOMY IN SPONTANEOUSLY BREATHING PATIENTS

OBJECTIVE: The purpose of this study was to determine the incidence of postoperative hypercarbia in patients undergoing intracranial neurosu rgery. Postoperative hypercarbia is a well-recognized cause of postope rative morbidity. METHODS: Sixty-four patients undergoing craniotomy w ere monitored in the first 36 postoperative hours using transcutaneous CO2 monitoring. We collected and analyzed demographic data, complete medical histories and examinations, and details of surgery, anesthesia , and postoperative progress. The accuracy of the transcutaneous CO2 m onitoring was evaluated by comparison with arterial blood gas CO2. INS TRUMENTATION: The ''TINA'' TCM3 Transcutaneous CO2 Monitor (Radiometer , Copenhagen, Denmark) was used. RESULTS: Thirty-nine patients (61%) d eveloped no hypercarbia. Nineteen patients (30%) developed mild to mod erate hypercarbia (46-59 mm Hg) and six patients (9%) developed severe hypercarbia (60 mm Hg or greater). Statistically significant differen ces were observed between the severely hypercarbic group and the other two groups combined, as follows: a higher incidence of preoperative a nd postoperative seizures, a lower average postoperative Glasgow Coma Scale score, a higher incidence of reintubation and ventilation, and a higher degree of intraoperative brain disturbance. Analysis of transc utaneous CO2 measurements and time-matched arterial blood gas CO2 meas urements revealed an acceptable accuracy of the transcutaneous method. CONCLUSION: This study demonstrates that, in routine neurosurgical pr actice, a subgroup of patients are at risk of developing postoperative hypercarbia, which may be more common than is generally recognized an d will not usually be detected by routine postoperative monitoring. Tr anscutaneous CO2 monitoring is a useful technique that may impact mana gement decisions.