[Effect of fentanyl and enflurane on sensory evoked potentials in the human in basic flunitrazepam/N2O anesthesia]. / Wirkung von Fentanyl und Enfluran auf sensorisch evozierte Potentiale des Menschen in Flunitrazepam/N2O-Basisnarkose.

The use of evoked potential recording is commonly employed for monitoring peripheral and central sensory functions during neurosurgical procedures. However, the neuronal structures studied must not be changed by the anesthetic agents used. In this connection, the influence of two anesthetics, fentanyl and enflurane, on evoked potentials was investigated under basic anesthesia. A total of 60 patients undergoing lumbar disc removal were included in the study. Somatosensory (SEP), auditory (AEP), and visual (VEP) evoked potentials were each recorded in 20 patients the day before operation. Basic anesthesia was induced with flunitrazepam, nitrous oxide, and pancuronium bromide. Following induction, recordings of evoked potentials were again made. One half of each group of 20 patients received increasing doses of fentanyl (1.8, 3.6, and 7.2 micrograms/kg in the somatosensory and auditory groups; 4.0 and 8.0 micrograms/kg in the visual group). The other half was given increasing inspiratory concentrations of enflurane (0.5, 1.0, and 1.5 vol.%). At each level of anesthesia, SEPs, AEPs or VEPs were recorded. As compared with preoperative recordings, post-stimulus latencies were virtually unaffected by the basic anesthesia. Fentanyl caused little increase in the latencies of middle-latency-SEPs and of peak P2 of the VEPs. With enflurane, however, the latencies of the SEPs were dose-dependently prolonged, in particular those of the later components (P25 to N55). The same was true for the peak P2 in the VEPs. AEPs were not changed at all. From the results it can be concluded that enflurane, but not fentanyl, impairs impulse conduction in central synaptic pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in water balance and kidney function caused by cardiopulmonary bypass]. / Veränderungen von Wasserhaushalt und Nierenfunktion durch den kardiopulmonalen Bypass.

The authors studied in 42 patients, 35 normotensives and 7 hypertensives, undergoing open-heart surgery, the perioperative behaviour of renal function and fluid balance. Before cardio-pulmonary bypass (CPB), there was a prerenal impairment of renal function caused by reduced fluid intake. During CPB a marked osmolal diuresis without tubular failure occurred. The amount of positive fluid balance was proportional to the duration of CPB. In those hypertensive patients in whom CPB perfusion pressure was below 50 mmHg, the creatinine clearance decreased by 67% during this period. The results indicate that the extent of CPB-induced renal dysfunction is tolerable and does not result in renal failure provided an adequate perfusion pressure is maintained. However, the consequences of marked water retention for undisturbed vital organ function must be taken into consideration.