ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Fentanyl and alfentanil produce very similar electroencephalographic (EEG) changes in humans. With increasing serum concentrations of either narcotic, progressive slowing in frequency occurs. This narcotic effect on the brain was quantitated using off-line EEG power spectrum analysis. During EEG recording, six unpremedicated patients received a fentanyl infusion (150 μg/min), and six received alfentanil (1,500 μg/min) until a specific level of EEG depression (delta waves) occurred. Timed arterial blood samples were obtained for measurement of the narcotic serum concentrations. The narcotic-induced EEG changes were found to lag behind (in time) the serum narcotic concentration changes. To accurately relate EEG changes to serum narcotic concentrations, a pharmacodynamic model (inhibitory sigmoid Emax) was combined with a pharmacokinetic model that incorporated an “effect” compartment. (The effect compartment is the separate pharmacokinetic compartment where drug effect is directly proportional to drug concentration. It is the effect site.) The magnitude of the time lag was quantitated by the half-time of equilibration between serum narcotic concentrations and concentrations in the effect compartment. With fentanyl a significantly greater time lag was present (half-time = 6.4 · 1.3 min; mean ± SD) than with alfentanil (half-time = 1.1 · 0.3 min). This difference in time lag between blood concentration and effect may be due to the larger brain-blood partition coefficient for fentanyl. The steady-state serum concentration that caused one-half of the maximal EEG slowing was 6.9 · 1.5 ng/ml for fentanyl, compared with 520 · 163 ng/ml for alfentanil. Although fentanyl is reported to have a dose potency approximately seven times that of alfentanil, the steady-state serum concentration potency ratio calculated from this study is approximately 75 to 1. This difference may be explained by alfentanil's smaller initial distribution volume and less time lag between serum concentration changes and changes in effect.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The effects of upper abdominal surgery on diaphragmatic function were studied in eight supine patients before and after administration of aminophylline. Changes in pleural (ΔPpl) and gastric pressure (ΔPga) swings were measured with balloon catheter systems. Transdiaphragmatic pressure change (ΔPdi) was calculated as the difference ΔPga-ΔPpl. The ratio ΔPga/ΔPdi, used as an index of the diaphragmatic contribution to the quiet breathing process, decreased significantly as early as 1 h after operation without any further change throughout the 6-h period studied. Administration of aminophylline (6 mg/kg), six hours postoperatively, produced a significant increase in this diaphragmatic index. These data indicate that the early reduced diaphragmatic activity, after upper abdominal surgery, partially may be reversed by administration of aminophylline. The mechanism of its action may involve central nervous stimulation and/or a direct inotropic effect on diaphragmatic muscle. Further studies are needed to evaluate if the correction of altered diaphragmatic motion by aminophylline improves postoperative lung function.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Functional residual capacity (FRC), rib cage and abdominal dimensions (rc-ab), central blood volume (CBV), and extra vascular lung water (EVLW) were measured in six lung-healthy subjects awake and during halothane anesthesia, muscle paralysis, and mechanical ventilation. FRC was assessed by multiple breath nitrogen washout, rc-ab dimensions by computerized tomography, and CBV and EVLW by a double-indicator dilution technique (thermo-dye). During anesthesia, FRC decreased by 0.5 1 (17%). The cross-sectional chest area was reduced by 12–20 cm2, causing an approximate reduction in thoracic volume by 0.3 1. Concomitantly, the diaphragm was moved cranially by an average of 1.9 cm, diminishing the thoracic volume a further 0.5 1. The abdominal cross-sectional area did not alter significantly, despite the shift of the diaphragm. CBV decreased by 0.3 1. EVLW did not change significantly. It is concluded that the thoracic volume is reduced during halothane anesthesia, muscle paralysis, and mechanical ventilation as a result of cranial shift of the diaphragm and reduction in transverse area. The decrease in thoracic volume is accompanied by a reduction in FRC and a displacement of blood from the thorax to the abdomen, the transverse area of the latter thus being maintained despite the shift of the diaphragm.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The effects of a single oral dose or chronic ingestion of ethanol onin vivoandin vitrometabolism of enflurane were studied in Fischer 344 rats. At various intervals after ethanol treatment, enflurane was administered ip and 1 h after enflurane administration fluoride and ethanol levels were measured in plasma and hepatic microsomes were prepared. The concentration of ethanol in plasma (±SE) was 0.138 · 0.035% at 9 h after the single dose of ethanol and decreased almost to control levels by 17 h. The hepatic microsomal defluorination of enflurane was enhanced 3.5-fold and 6.3-fold at 9 and 25 h after the ethanol dose and returned to the control level by 33 h.In vivodefluorination was inhibited almost completely at 8 h after the ethanol dose, increased to 3.4 times the control level at 24 h, and decreased to the control level by 32 h. At 1 h after the end of chronic ethanol treatment, the concentration of ethanol in plasma was 0.254 · 0.018%, and it decreased to the control level by 9 h. Hepatic microsomal enflurane defluorinating activity was increased 10.5-fold at 1 h after the end of chronic treatment and decreased to the control level by 13 h. Immediately following chronic treatment, enflurane defluorinationin vivowas almost totally inhibited. It increased to 9.3 times the control level at 4 h after chronic treatment was stopped and then decreased to nearly the control level at 12 h. Changes in hepatic microsomal enflurane defluorinating activity following ethanol administration were paralleled by changes in the amount of a microsomal protein that electrophoresed in the molecular weight region of the cytochrome P-450 isozymes. The results show that ethanol can produce a very rapid increase in hepatic microsomal enflurane defluorinating activity in rats and provide evidence that this increase results from the induction of a form of cytochrome P-450. Defluorination of enfluranein vivocan be inhibited or stimulated following treatment with ethanol, depending on the level of ethanol present when the enflurane is administered.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

In this study, 50 patients received an initial bolus epidural injection of 2 mg morphine–hydrochloride followed by a continuous-plus-on-demand epidural infusion of a 0.25% morphine-hydrochloride solution by means of a small, externally worn infusion device, for constant pain relief after abdominal operations. Mean morphine consumption on the operation day (until 8:00 AM on the first postoperative day) was 4.8 · 0.2 mg, on the first postoperative day (until 8:00 AM on the second postoperative day) 1.9 · 0.2 mg, and on a second postoperative day until 8:00 PM, 0.6 · 0.1 mg. The mean morphine consumption over 50 h was 7.1 · 0.3 mg; in the first 25 h and in the following 25 h after the operation, 5.44 · 0.3 mg and the significantly lower amount of 1.64 · 0.2 mg morphine, respectively, were consumed (P< 0.001). There were no serious side effects. Serum levels of free, unmetabolized morphine immunoreactivity decreased during the treatment. The described method is recommended for treating postoperative pain, as it offers constant analgesia and the possibility of individualized treatment.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The reduction in cerebral blood flow (CBF) caused by hypocapnia is an important element of neuroanesthesic techniques. While it has been demonstrated previously that the CO2response of the cerebral circulation (CO2· R) is enhanced (i.e., greater ΔCBF/ΔPaCO2) during halothane administration, the effect of isoflurane on CO2· R has not been evaluted completely. Accordingly, the authors examined CO2· R in cats during anesthesia with 1.0 MAC isoflurane (with 75% N2O) and compared it with CO2· R during anesthesia with 1.0 MAC halothane (with 75% N2O) and with CO2· R during the administration of 75% N2O alone.CO2· R during anesthesia with isoflurane–N2O was enhanced relative to that observed during administration of both halothane–N2O (P< 0.025) and N2O alone (P< .001). CO2· R during anesthesia with halothane–N2O was, in turn, greater than that observed during the administration of N2O alone (P< 0.025). Furthermore, at similar levels of hypocapnia (PaCO218–20 mmHg), CBF was significantly lower (P< 0.01) during administration of isoflurane–N2O (29.0 · 4.5 ml · 100 g−1· min−1) than during administration of either N2O (40.6 · 5.5 ml · 100 g−1· min−1) or halothane–N2O (39.6 · 7.8 ml · 100 g−1· min−1). CBF values during administration of the N2O alone and halothane–N2O were not different during hypocapnia.The results of this study indicate that CO2· R in cats not only is preserved during administration of 1.0 MAC isoflurane (with 75% N2O) but is enhanced relative to that observed during anesthesia with 1.0 MAC halothane (with 75% N2O) and during sedation with N2O alone. In addition, the induction hypocapnia (PaCO218–20 mmHg) resulted in a reduction of CBF to lower levels during the administration of isoflurane–N2O than during administration of halothane–N2O or N2O alone. If the cerebral circulation of anesthetized humans responds similarly to that of the cat, these results suggest that the induction of hypocapnia during the administration of isoflurane (with N2O) may facilitate a greater reduction in CBF, and therefore perhaps ICP, than will occur at a comparable PaCO2during anesthesia with halothane (with N2O) or during the administration of N2O alone.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID