[The effect of high frequency jet ventilation on intracranial pressure in the patients with severe head injury].

The effect of high frequency jet ventilation (HFJV) on intracranial pressure (ICP) in the series of seven patients with severe head injury was studied. These patients received mechanical ventilation for respiratory failure accompanied with neural damage or circulatory shock and for ICP control by decreasing PaCO2. ICP was measured continuously by subarachnoid catheter method connected to Gould P-50 strain-gage transducer and controlled by hyperventilation and/or osmotic diuretics during acute phase. Arterial pressure, central venous pressure and intratracheal pressure were measured continuously in the same way. Arterial blood gases were analysed by BG-I of Technicon Co. Ltd. At the weaning from respirator, two methods were applied. One was conventional IMV (with PEEP) and/or CPAP by using IMV mode of Servo 900 respirator or T-piece together with PEEP valve and another was new-fashioned HFJV. Mean intratracheal pressure (mPit) was fixed at 0 mmHg (control value), 5, 10 and 15mmHg in both methods by adjusting PEEP valve or driving pressure of HFJV. The result is that in the same patients ICP was significantly lower during HFJV than IMV/CPAP when mPit was 5 and 10mmHg. Only three cases having been studied at 15mmHg of mPit because circulatory condition would not permit it, significant difference of ICP between HFJV and IMV/CPAP was not detected. PaCO2, being suspected to be the cause of lower ICP of HFJV group, was studied too. But blood gas analysis showed no significant difference neither PaCO2 nor PaO2. The fluctuation of CVP reflecting the change of intrathracic pressure was smaller in HFJV group than in IMV/CPAP group.(ABSTRACT TRUNCATED AT 250 WORDS)