The continuous measurement of cerebrospinal fluid gas tensions in critically ill neurosurgical patients: a prospective observational study.
OBJECTIVE
To determine the feasibility and usefulness of continuous cerebrospinal fluid pH and gas tension monitoring in critically ill neurosurgical patients.


METHODS
Prospective, observational study.


METHODS
Neurosurgical intensive care unit in a teaching hospital.


METHODS
Five critically ill neurosurgical patients (GCS < 8) requiring intensive care intracranial pressure monitoring and intermittent positive pressure ventilation.


METHODS
Placement of a Paratrend 7 sensor into the external ventricular drain.


RESULTS
The cerebrospinal fluid (CSF) pH, PCO2 and PO2 were recorded at 1-min intervals. Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were recorded at 15-min intervals. The mean baseline CSF pH, O2 and PO2 values were 7.28 +/- 0.08 pH units, 44 +/- 6 torr and 43 +/- 27 torr, respectively. The ranges of CSF pH, PCO2 and PO2 observed during the study were 6.3-7.8 pH units, 37-150 torr and 4-150 torr, respectively. A statistically significant correlation between ICP, CPP and CSF gas tensions occurred in patient 3. Significant changes in CSF PO2 and pH were observed with augmentation of CPP and preceded clinical improvement in patient 4. There were no complications attributable to sensor placement. CSF gas tensions and pH values obtained from patients 3 and 4 suggest that these measurements may be an indicator of cerebral perfusion.


CONCLUSIONS
Continuous CSF gas tension measurements in critically ill patients are possible and may be an indicator of adequacy of cerebral perfusion. The relative merits and limitations of the technique are discussed.
Venkatesh
B
B
Department of Intensive Care Medicine, Royal Brisbane Hospital, Queensland, Australia.
Boots
R
R
Tomlinson
F
F
Jones
R D
RD
D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000134:cerebrospinal fluid / Q000503:physiopathology / Q000601:surgery; D002245:Carbon Dioxide / Q000134:cerebrospinal fluid*; D002543:Cerebral Hemorrhage / Q000134:cerebrospinal fluid / Q000503:physiopathology / Q000601:surgery; D003422:Critical Care; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D010100:Oxygen / Q000134:cerebrospinal fluid*; D010477:Perfusion; D011446:Prospective Studies
D002245:Carbon Dioxide; D010100:Oxygen