engleski

Hyperventilation and secondary brain injury

Mechanical hyperventilation is widely used in patients with severe brain injury. It is very well documented that mechanical hyperventilation can cause the secondary brain injuries and brain schema The use of continuos jugular bulb oximetry demonstrated that a great number of desaturations occurred during hyperventilation and they were associated with poor outcome. Jugular bulb oximetry was proposed to be used in patients with severe head injury only if hyperventilation of < 30 mmHg is need. The objective of this study was the evaluation of continuos SjO2 monitoring on the optimal ventilator settings in severe head injured patients. Patients and Methods: 20 patients with severe head injury were included in the study (Glasgow Coma Scale score < 8). All the patients were mechanically ventilated to PaCO2 of about 35 mmHg. Continuous monitoring of ICP with Codman MicroSensor ICP intraparenchymal transducer, arterial pressure, endexpiratory CO2 and pulse oximetry was started as soon as possible. Continuous monitoring of SjO2 was performed with Opticath 4F catheter and Oximetric 3 System (Abbott). All the patients included in the study had cerebral perfusion pressure of at least 60 mmHg. Results: Periods of desaturation (SjO2 below 55%) were observed in 4 of 13 patients who had ICP below 20 mmHg. The lowering of minute ventilation resulted in satisfactory values of SjO2 in 3 of 4 patients. Too high jugular bulb saturation (SjO2 above 75%) was detected in 7 patients. All of them had elevated ICP (21-62mmHg). In 5 of that 7 patients, the increasing of minute ventilation to keep endexpiratory CO2 between 25 and 30 mmHg, and application of manitol resulted in satisfactory values of SjO2 and decreased ICP. Some patients had satisfactory SjO2 only with normoventilation. With initial ventilation to PaCO2 of about 35 mmHg to high jugular bulb values with increased ICP can occur, but is some patients desaturation periods were also noticed. Conclusions: Our data confirm the need for optimized hyperventilation in severe brain injury patients. Our opinion is that that continuous monitoring of SjO2 has to be routine monitor in all patients with severe traumatic brain injury together with ICP and MAP monitoring. Continuos monitoring of SjO2 in severe brain injury patients can prevent period of desaturations and secondary brain injury.

hyperventilation; severe brain injury;

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