ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Dopamine and dobutamine were administered to 12 patients who had undergone open cardiac operations. To eliminate the effects of variation in systemic blood flow upon renal function the drug infusion rates were adjusted to achieve equal cardiac outputs. Under conditions of equivalent systemic pressure and flow, dopamine (5.0 ± 1 μg · kg-1· min-1) and dobutamine (3.5 ± 1.8 μg · kg-1· min-1) had similar effects upon glomerular filtration rate (90 ± 29vs.83 ± 27 ml · min-1· 1.73 m-2) and effective renal plasma flow (375 ± 119vs.357 ± 126 ml · min-1· 1.73 m-2). However, dopamine administration resulted in a significantly greater diuresis (2.8 ± 2.7vs.1.0 ± 0.3 ml/min), natriuresis (0.32 ± 0.39vs.0.07 ± 0.10 mEq Na+/min), and kaliuresis (0.15 ± 0.06vs.0.10 ± 0.03 mEq K+/min) (P< 0.05). In patients with modest depression of cardiac performance and renal vasoconstriction, dopamine's selective renal vasodilator effects were not evident. Furthermore, these data suggest that dopamine inhibits tubular solute reabsorption directly. Thus, the diuresis and natriuresis that frequently accompany dopamine administration may occur independently of any effects of dopamine upon renal blood flow.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The hemodynamic, electroencephalographic (EEG), and metabolic effects of a high-dose methohexital anesthetic were examined in eight neurosurgical patients. The patients were studied at rest and at 15-min intervals during a 60-min infusion of the drug, given at a rate of 0.40 mg · kg-1· min-1(total dose 24 mg/kg). Ventilation was controlled with oxygentair (FIO2= 0.50), and fluid was infused at a rate sufficient to maintain pulmonary capillary wedge (PCW) pressures at control values (8 ± 2 mmHg, mean ± SD). Serum methohexital concentrations increased progressively, reaching values of 11.7 ± 2.9 μg/ml at t = 30 min and 18.1 ± 10.8 μg/ml at t = 60 min. Characteristic barbiturate-induced EEG changes were noted, with isoelectricity achieved at t = 28 ± 13 min.Methohexital infusion resulted in significant reductions in arterial pressure (84% of control at t = 60 min), systemic vascular resistances (83% of control at t = 60 min), right and left ventricular stroke work indices (65% and 68% of control, respectively at t = 60 min), and total body O2consumption (76% of control at t = 60 min). In addition, a progressive dose-related decrease in stroke volume index was noted (50.1 ± 90 ml ± beat-1· m-2at t = 0, 40.1 ± 10.2 ml · beat-1· m-2at t = 60 [80% of control]). This occurred in spite of unchanged ventricular filling pressures. However, cardiac index was well maintained (unchanged at t = 60 min) because of increases in heart rate (123% of control at t = 60 min). There was no change in PaO2, PaCO2, or pulmonary vascular resistance.These data demonstrate that doses of methohexital sufficient to produce profound EEG suppression are accompanied by both vasodilation and some depression of myocardial function, even when ventricular filling pressures are maintained. Nevertheless, the magnitude of these changes suggests that high doses of methohexital may be a hemodynamically acceptable form of anesthesia for certain restricted neurosurgical procedures. However, refractory postoperative seizures occurring in three patients indicate that this anesthetic technique has potentially serious associated difficulties. For this latter reason, the authors have suspended their use of methohexital and are examining the utility of alternative barbiturates.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The pharmacokinetics of sufentanil, a new thienyl analogue of fentanyl, were studied in 10 surgical patients. Sufentanil, 5 μg/kg, was given intravenously as a bolus injection and plasma concentrations measured at intervals up to 8 h. Plasma sufentanil concentrations decreased rapidly after injection—98% of the administered dose having left the plasma within 30 min. In 9 of the 10 patients, a tri-exponential equation optimally described the sufentanil concentration decay curve, with average (±SEM) half-lives for the rapid (π) and slow (α) distribution phases of 1.4 ± 0.3 min and 17.7 ± 2.6 min, respectively. The average terminal elimination (β) half-life was 164 ± 22 min. The average value for Vdβ was 2.9 ± 0.2 1/kg, Vdss1.7 ± 0.2 1/kg and total plasma clearance 12.7 ± 0.8 ml · kg-1· min-1(935 ± 50 ml/min). In one patient, a biexponential equation was sufficient to describe the concentration-time data, yielding a distribution half-life of 4.7 min and an elimination half-life of 117 min.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The principal site of action of intravenous regional anesthesia was studied using both prilocaine HCl 0.5% and technetium pertechnetate to define their distribution in the upper limb during this method of anesthesia. Using a single upper arm tourniquet and injecting technetium pertechnetate into a cubital fossa vein, the isotope spread to the finger tips. When a double tourniquet system was used to isolate the hand from the forearm, the following results were obtained: for up to 20 min after injection of the 40 ml of normal saline and radioisotope there was no leakage into the general circulation nor into the hand; after injection of 40 ml prilocaine HCl 0.5% into a cubital fossa vein, there was no anesthesia in the hand except for a small area on the dorsum corresponding to the area of sensory distribution of the radial nerve; while the tourniquets were inflated there was cramping pain in the hand. The results indicate that the initial analgesia obtained with the intravenous regional technique was due to blockade of small nerves or possibly nerve endings and not of the major nerve trunks at the elbow as has been suggested previously.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Eleven patients with acute respiratory failure due to diffuse, bilateral lung disease were treated according to a new ventilation concept. The patients were intubated with a double-lumen catheter and positioned in the lateral decubital posture. With two synchronized ventilators, each lung received half of the tidal volume (VT), in accordance with its presumed perfusion (differential ventilation—DV), and the end-expiratory pressure was increased locally in the dependent lung (selective PEEP). DV with and without selective PEEP was compared with conventional ventilation with free distribution of VT, with and without PEEP applied to both lungs. The major findings were that DV with a selective PEEP of 12 cmH2O to the dependent lung decreased venous admixture by 38% (P< 0.01) in comparison with conventional ventilation with no PEEP. Furthermore, it was found that selective PEEP, in contrast to general PEEP, had no deleterious effect on cardiac output. Consequently, DV with selective PEEP increased arterial oxygen tension by 23% (P< 0.05) compared with general PEEP and by 46% (P< 0.001) in comparison with conventional ventilation with no PEEP.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

To determine whether paralysis reduces oxygen consumption (VO2) after cardiac surgery in infants, the authors measured VO2before and after paralysis in 17 sedated infants who were ventilated mechanically after cardiac surgery. Oxygen consumption was determined as being the difference between oxygen content of inspired and expired gases. The absence or presence of “movement” (breathing or repeated movement of the extremities) before paralysis was noted. For eight infants who did not “move” before paralysis, VO2was similar before (9.1 ± 1.2 ml · kg-1· min-1, mean ± SD) and after (9.0 ± 1.5 ml · kg-1· min-1) paralysis (P= 0.81). However, for nine infants who did “move” before paralysis, VO2decreased from 9.2 ± 1.4 ml · kg-1· min-1before paralysis to 8.0 ± 1.4 ml · kg-1· min-1after paralysis (P< 0.05). One infant in each group had an increase in VO2greater than 10% of the baseline value (i.e., 12% and 14%). In conclusion, if breathing or repeated movement is present before paralysis, paralysis decreases VO2by 13% in sedated infants after cardiac surgery. If repeated or regular movement is not present before paralysis, paralysis does not decrease VO2. These data suggest that in normoxic patients, muscle paralysis does not significantly alter VO2and therefore should not be used for this purpose.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Each of six healthy volunteers was studied on three different occasions to determine the interactions of placebo–physostigmine, diazepam–physostigmine, and morphine–physostigmine with respect to respiration and psychomotor function. Respiratory measurements were made using the steady state and isohypercapnic techniques. Psychomotor function was assessed by the Trieger Dot Test (TDT) and compared with the Continuous Performance Test (CPT). Administration of physostigmine alone (3 mg, iv) did not affect ventilation. Diazepam (0.29 mg/kg, iv) did not cause a significant depression of ventilation in all subjects, although psychomotor function was impaired as measured by the CPT. The latter was unaffected by physostigmine. Administration of morphine (0.21 mg/kg, iv) caused a significant decrease in ventilation that was not antagonized by physostigmine. Morphine did not impair psychomotor function. The authors conclude that physostigmine is an ineffective antagonist of narcotic-induced respiratory depression and that the CPT correlates well with the TDT.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Using the technique of ventriculocisternal perfusion, resistance to reabsorption of cerebrospinal fluid (Rss) was calculated from determinations of the rate of reabsorption of cerebrospinal fluid (Vss) at differing cerebrospinal fluid pressures in dogs. Rawas examined during prolonged anesthesia (5.0–6.0 h) with enflurane (2.2%, end expired) or isoflurane (1.4%, end expired). Compared with previously reported normal values for Rain dogs (220–224 cmH2O · ml-1· min), enflurane increased Rato 274 ± 4 cmH2O · ml-1· min (mean ± SEM), and isoflurane decreased Rato 104 ± 1 cmH2O · ml-1· min. The alterations of cerebrospinal fluid (CSF) dynamics caused by enflurane, namely increase of both Raand the rate of production of cerebrospinal fluid (Vss), may contribute to the sustained increase of intracranial pressure observed during prolonged anesthesia with enflurane. In contrast, the different alterations of CSF dynamics caused by isoflurane, namely decrease of Rawith no change in Vss, may explain, in part, why minimal increase of intracranial pressure is observed during prolonged anesthesia with isoflurane. Because decreased Rsimproves spatial compensation by cerebrospinal fluid volume for increased intracranial pressure, isoflurane may offer an advantage over enflurane in patients at risk because of increased intracranial pressure.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The authors sought to determine whether the metabolites of neostigmine and pyridostigmine contribute to antagonism of neuromuscular blockade. Accordingly, the dose-response relationship, onset and duration of action (n = 60), and pharmacokinetics (n = 22) of neostigmine, pyridostigmine, their metabolites 3-hydroxyphenyltrimethylammonium (PTMA) and 3-hydroxy-N-methylpyridinium (MP), and edrophonium were determined in dogs anesthetized with sodium pentobarbital. The force of contraction of the anterior tibialis muscle was maintained at constant 90% depression by infusing pancuronium. Then, a single iv bolus dose of one of the drugs under study was injected while the pancuronium infusion was continued. Venous blood, urine, and bile were sampled for four hours. Concentrations were determined by liquid chromatographic techniques; a three-compartment pharmacokinetic model was fitted to the serum concentration data. The doses producing 50% antagonism were 6.5, 52, 69, and 40 μg/kg for neostigmine, pyridostigmine, edrophonium, and PTMA, respectively. MP was inactive as an antagonist. By comparing approximately equipotent doses, time to peak antagonism (onset) and until 30% of peak antagonism remained (duration) were shorter for both edrophonium and PTMA than for neostigmine and pyridostigmine. Slow distribution and elimination half-lives, volume of distribution at steady state (VDss), and total plasma clearance (Cl) were similar for the drugs except for a smaller Vdssand lower Cl for MP. More than 60% of the dose of each drug was recovered unchanged from urine; less than 1% was recovered from bile. Less than 10% of the dose of neostigmine was recovered as PTMA. Since PTMA was a weak antagonist and MP had no antagonist activity, the authors conclude that their contribution to antagonism of neuromuscular blockade is minimal. Therefore, the slower onset of neostigmine and pyridostigmine than of edrophonium cannot result from the time required for the formation of their metabolites. Also, differences in potency and duration between the drugs cannot be explained by pharmacokinetics. These results support the belief that there are pharmacodynamic differences between the drugs.

ISSN:0003-3022    

出版商:OVID    

年代:1984

数据来源: OVID