High frequency jet ventilation.
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Combined Modality Therapy↗
Biomedical subjects
L Deen
Publications and source records attributed to L Deen.
Influence of changes in arterial carbon dioxide tension on the electroencephalogram and posterior tibial nerve somatosensory cortical evoked potentials during alfentanil/nitrous oxide anesthesia.
The effects of variation of arterial CO2 tension (PaCO2) on the electroencephalogram (EEG) and posterior tibial nerve somatosensory cortical evoked potentials (PTN-SCEP) during opioid/N2O anesthesia have not been well documented. We studied the effects of hypocapnia (PaCO2 approximately 23 mmHg) and hypercapnia (PaCO2 approximately 50 mmHg) during steady-state alfentanil/N2O anesthesia in 16 patients. EEG and PTN-SCEP were recorded continuously, while PaCO2 was altered in 15-min intervals by varying the inspired CO2 concentration. Hypocapnia caused significant increases in power in the delta, theta, and beta bands (P less than 0.01), with the greatest increase observed in the alpha band. Relative power increased in the alpha band but remained unchanged in the delta, theta, and beta bands. Median frequency and 95% spectral edge frequency were unaltered during hypocapnia. In contrast, hypercapnia caused a significant decrease of power in the alpha and beta bands, whereas delta and theta power remained unchanged. This was reflected in a significant decrease of the 95% spectral edge frequency, from 8.9 (6.7-11.6) to 7.0 (5.6-8.6) Hz. All EEG parameters returned to normal upon restoration of normocapnia. There was a significant negative correlation between power in the alpha band and end-tidal CO2 in all patients (r = 0.47 to -0.89). PTN-SCEP latencies and amplitudes were not significantly different from control values during hypocapnia and hypercapnia. It is concluded that variations in PaCO2 within the limits 20-50 mmHg produce substantial changes in the EEG power spectrum, especially in the alpha band (8-12 Hz), but do not alter PTN-SCEP.
Adult↗
[Halothane hepatitis].
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Chemical and Drug Induced Liver Injury↗
Nitrous oxide and mammary carcinoma.
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Adenocarcinoma↗
Oesophageal/transpulmonary pressure change ratios as a guide to lung compliance. A study in rabbits undergoing IPPV.
Experimental studies in ten anaesthetised rabbits suggest that oesophageal-transpulmonary pressure ratios can be correlated with trends in lung compliance during IPPV. The relevance and limitations of this technique are discussed as an alternative method of lung compliance measurement in the sick neonate.
Animals↗
Oesophageal pressure measurement in rabbits and human infants using an air-filled balloon system.
In ventilated anaesthetized rabbits the relationship between the oesophageal pressure and the intrapleural pressure, measured with an air-filled balloon system, was studied. A balloon 15 mm long and 3 mm diameter detected 95% of the measured intrapleural pressure, provided the balloon was positioned accurately. In babies undergoing IPPV, the best balloon position was in the lower third of the oesophagus. When synchronous spontaneous respiration occurred in the course of IPPV the mean of intrapleural pressure remained negative in spite of positive ventilating pressures in the range 30-45 cm H2O.
Air↗