ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Regional motion of the human diaphragm was determined by high-speed, three-dimensional x-ray computed tomography. Six healthy volunteers were studied first while awake and breathing spontaneously and again while anesthetized-paralyzed and their lungs ventilated mechanically. Tidal volume (VT) and respiratory frequency were similar during both conditions. Three subjects were studied while they were supine and three while they were prone. During spontaneous breathing, movement of dependent diaphragm regions was greater than that of nondependent regions in four of six subjects. In five of the six subjects, dorsal diaphragm movement exceeded ventral movement regardless of body position. The volume displaced by the diaphragm (ΔVdi) was similar to VTin supine subjects but tended to be less than VTin prone subjects. After induction of anesthesia-paralysis, the end-expiratory position of the diaphragm did not change consistently in supine subjects, whereas a consistent cephalad volume shift occurred in prone subjects. During anesthesia-paralysis and mechanical ventilation, ΔVdiwas reduced to approximately 50% of VTin both body positions. In the supine position, the pattern of diaphragm motion during mechanical inflation was nearly uniform. By contrast, in the prone position, the motion was nonuniform, with most motion occurring in the dorsal (nondependent) regions. It is concluded that the dominant influence on diaphragm motion may be some anatomical difference between the crural and costal diaphragm regions rather than the abdominal hydrostatic pressure gradient.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Reversal of the sedative and amnesic effects of intravenous diazepam by the benzodiazepine antagonist flumazenil was investigated in 30 patients undergoing conscious sedation for dental surgery. Verbal memory tasks were administered and patients' subjective ratings of mood were obtained before and after diazepam and then periodically after intravenous administration of flumazenil or placebo under double-blind conditions. Immediate and delayed recall and recognition tests showed that diazepam impaired memory and that flumazenil partially reversed this impairment. The subjective ratings showed that diazepam produced physical and mental sedation and that flumazenil reversed this sedation. The reversal produced a return to presurgery scores for mental sedation but not for physical sedation or memory. For physical sedation, the difference between flumazenil and placebo was not demonstrable for more than 15 min after flumazenil administration; for mental sedation, it was demonstrable for as long as 60 min. The reversal by flumazenil of diazepam-induced memory impairment did not change significantly over time.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Laboratory and clinical evidence of the inhibition of plasma cholinesterase by metoclopramide was demonstrated. When succinylcholine is used as the substrate and the product choline assayed by choline oxidase-peroxidase-quinone dye colorimetry, the rate of the choline production as optical density change was reduced to 50% by 19.5 X 10−6M metoclopramide at 20° C. Prolongation of neuromuscular blockade produced by concurrent administration of succinylcholine and metoclopramide was studied in 22 patients aged between 18 and 40 years undergoing elective gynecological surgery. EMG activity in the adductor pollicis muscle was recorded in response to a train-of-four (TOF) stimulus delivered every 10 s. Patients were randomly divided into two groups: A and B. In both groups, anesthesia was induced with thiopental and maintained with sufentanil and nitrous oxide. Tracheal intubation followed intravenous succinylcholine. Intraoperatively, after returning of neuromuscular function, patients in both groups received 20 mg succinylcholine for the determination of duration of neuromuscular blockade. Time from 95% suppression of baseline twitch following a 20 mg increment of succinylcholine until recovery to 25% of control activity was determined. Thereafter, in group A, patients receive metoclopramide (10 mg iv) followed by succinylcholine 20 mg iv, and patients in group B received succinylcholine 20 mg iv alone. Recovery times were again measured and found to be prolonged in patients receiving metoclopramide compared with those not receiving metoclopramide (P< 0.05). Metoclopramide has no intrinsic neuromuscular blocking activity, but its ability to inhibit plasma cholinesterase probably is the mechanism by which it prolongs succinylcholine block. Reducing the dose of succinylcholine may be appropriate when metoclopramide is given concurrently.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

The effects of local infiltration anesthesia, brachial plexus blockade, isoflurane, or halothane anesthesia on blood flow through the brachial artery and through a newly created forearm arteriovenous fistula (AVF) were compared in 36 patients with endstage renal failure. Brachial artery blood flow was measured at two different times, before anesthesia and during anesthesia but before surgery, using a pulsed Doppler flowmeter. AVF flows were calculated from brachial, radial, and ulnar blood flows at the end of surgery, 2 h after surgery, and 3 and 10 days after the procedure. Mean arterial pressure was lower in patients receiving isoflurane or halothane than in those receiving local anesthesia or brachial plexus blockade (BPB). There was a significant increase in brachial artery blood flow following BPB (43.7 ± 18.7 to 186.9 ± 98.2 ml.min−1) during isoflurane anesthesia (46.2 ± 15.9 to 153.1 ± 80.5 ml.min−1) and during halothane anesthesia (49.9 ± 24.1 to 97.6 ± 62.1 ml.min−1). During anesthesia, the difference in brachial artery blood flow between patients in the BPB and halothane groups was significant. Local anesthesia failed to increase brachial artery blood flow (44.0 ± 12.7 to 45.6 ± 11.3 ml.min−1). In the immediate postoperative period, the AVF blood flow was lower in patients in the halothane group than in the other groups, but this difference was only significant when compared with BPB group. In the late postoperative period, AVF blood flows were lower in patients in the local anesthesia group than in the other groups. The authors conclude that the highest AVF blood flow with the least hemodynamic changes was obtained with the BPB technique. Nevertheless, the four types of anesthesia used in this study were suitable for this procedure, since no thrombotic complications occurred.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

The relative potency and speed of onset of action of pancuronium, gallamine, and d-tubocuraine was studied in 55 adult female patients receiving nitrous oxide/oxygen-narcotic anesthesia. The integrated electromyogram of the adductor pollicis muscle was monitored using a cumulative dose-response technique; train-of-four stimuli were administered at 0.05 Hz. The measured ED95values for pancuronium and gallamine were 0.069 and 2.38 mg/kg, respectively. In three separate groups, pancuronium 0.07 mg/kg, gallamine 2.4 mg/kg, or d-tubocurarine 0.45 mg/kg were given as a single bolus and the speed of onset and time to maximum effect determined. Peak twitch depression was essentially identical in all groups (92.7 ± 1.4 [SE]vs.93.3 ± 1.1vs.93.7 ± 1.1%, respectively). The rate of onset of neuromuscular blockade in these three groups was, however, quite different. After administration of pancuronium (n = 10) the times to 5%, 20%, 50%, and 80% twitch depression were 68 ± 5, 97 ± 6, 141 ± 8, and 222 ± 18 s. The comparable times following gallamine (n = 10) were 29 ± 2, 42 ± 3, 66 ± 5, and 136 ± 14 s; d-tubocurarine (n = 10) was intermediate in speed with onset times of 40 ± 4, 63 ± 6, 99 ± 11, and 178 ± 25 s. It appears that the onset times of different nondepolarizing blocking agents (even when given in equipotent doses) may vary by clinically appreciable amounts. The results of this study support the hypothesis that nondepolarizing neuromuscular blocking agents of low potency may have a more rapid onset of action than that seen with agents of high potency.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Total respiratory compliance (Crs) has not previously been measured from the static pressure-volume (P-V) curve during spontaneous breathing in anesthestized infants and children. A single breath test and a volume recruitment maneuver for measuring Crs were applied to 18 infants and children breathing spontaneously during halothane anesthesia in order to determine the usefulness and reliability of these noninvasive tests for measuring static compliance during anesthesia. Crs from the single breath test (Crsab) was determined from the mask pressure plateau (P) during a brief end-inspiratory airway occlusion and the lung volume (V) from the passive expiration following release of the occlusion. Crs from the volume recruitment maneuver (Crsvr) was determined from P and V during a series of expiratory occlusions at progressively higher lung volumes. The P-V curves fit a polynomial curve with the convexity toward the pressure axis in most patients, and Crsvrwas the tangent to the curve in the mid-tidal range. The tallest four patients did not show respiratory muscle relaxation during the occlusions with either test, and the single breath test could not be completed in an additional two patients. In the 12 patients (59–89 cm in height) in whom both tests were successful, Crsabcorrelated with, and was similar to, Crsvr*The intrasubject coefficient of variation was less with the single breath test (9.4 ± 6.7%) than with the volume recruitment maneuver (15.0 ± 7.1%). The authors conclude that both tests are simple, reliable, and rapid and give similar results for Crs in spontaneously breathing children (59–89 cm in height) anesthetized with halothane.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Fentanyl was administered intravenously and transdermally to eight surgical patients to determine the systemic bioavailability and rate of absorption of the transdermally administered drug. Serum fentanyl concentrations reached a plateau approximately 14 h after placement of the transdermal fentanyl delivery system. This plateau was maintained until removal of the system at 24 h. The decline in serum fentanyl concentrations after removal of the transdermal system had a terminal half-life of 17.0 ± 2.3 h (mean ± SD), considerably longer than the terminal elimination half-life seen after intravenous administration of fentanyl in the same patients (6.1 ± 2.0 h). The rate of fentanyl absorption, predicted to be 100 μg/h fromin vitrodata, appeared to be relatively constant during a period starting 4–8 h after placement of the transdermal system until removal of the system at 24 h. The rate of absorption during this period was 91.7 ± 25.7 μg/h. After removal of the transdermal fentanyl delivery system, absorption continued at a declining rate. This indicates that the long terminal half-life of serum fentanyl concentrations after transdermal system removal is due to continued slow absorption of fentanyl, probably from a cutaneous depot of drug at the site of prior transdermal system placement. At the time of removal of the transdermal fentanyl system, 1.07 ± 0.43 mg of drug remained in this depot. Systemic fentanyl bioavailability was found to be 0.92 ± 0.33, with no evidence of significant cutaneous metabolism or degradation by the skin's bacterial flora. The transdermal administration of fentanyl produces relatively constant serum fentanyl concentrations for significant periods of time in the postsurgical patient requiring analgesic therapy.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

To test whether the radial artery-to-aorta pressure gradient seen in some patients after cardiopulmonary bypass (CPB) is due to reduction in hand vascular resistance, the authors compared pressures in the ascending aorta with pressures in the radial artery before and after CPB in 12 patients. They increased hand vascular resistance by briefly occluding the radial and ulnar arteries at the wrist and recorded that effect on the radial artery-to-aorta pressure relationship. They also recorded the effect of wrist compression on radial artery pressures before and after CPB in 38 patients not having aortic pressure measurements. Before CPB in the first 12 patients, the radial systolic arterial pressure (SAP) was significantly higher (P< 0.05) than the ascending aortic SAP, and wrist compression did not significantly affect that difference (P> 0.05). After CPB, the radial artery and aortic SAPs were not statistically different (P> 0.05), but wrist compression restored the higher radial artery SAP. The mean arterial pressure (MAP) was equal in four patients and 1–3 mmHg higher or lower in eight patients before CPB, and wrist compression did not alter those relationships. After CPB, MAP was equal in four patients; radial MAP was 1–3 mmHg higher or lower in six patients, and 7 and 10 mmHg lower in the last two patients. Wrist compression did not affect the dispersion around the zero mark in the first ten patients, but it increased radial MAP by 7 mmHg in the last two patients. In the final 38 patients, wrist compression did not affect radial MAP before CPB, but increased it by 7–12 mmHg in six patients after CPB. This increase was statistically significant (P< 0.05). These findings strongly suggest that a radial artery pressure lower than the aortic pressure after CPB is due mainly to a marked decrease in hand vascular resistance.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Pharmacokinetics and blood concentrations of bupivacaine were studied after intercostal nerve blocks were performed intraoperatively using 1.5 mg.kg−1in 11 neonates (age 0–28 days) and 11 infants between age 1 and 6 months. The study aimed to provide pharmacokinetic data that are limited in these age groups, and to identify any adverse effects of intercostal nerve block in infancy. Arterial blood samples were taken at 0, 5, 10, 15, 20, 30, 60, 120, 240, and 360 min. Whole blood bupivacaine was assayed by high-performance liquid chromatography. Peak blood concentrations were attained within 10 min in 18 of 22 subjects, and were 0.82 ± 0.56 μg.ml−1(mean and SD) and 0.91 ± 0.27 μg.ml−1in neonates and infants, respectively. Pharmacokinetic variables in the two groups included elimination half-life (t1/2β): 132 ± 59 min and 102 ± 39 min; steady-state volume of distribution (Vdss): 2.56 ± 0.76 1.kg−1and 2.17 ± 0.17 1.kg−1; and total body clearance (Clt): 16.93 ± 9.32 ml.min−1.kg−1and 15.71 ± 6.99 ml.min−1.kg−1. There was no statistically significant difference between neonates and infants with regard to any of these parameters. Patients were further divided into those with acyanotic and cyanotic disease. Cyanotic infants were significantly heavier than acyanotic infants (P< 0.05), but no other differences were demonstrated. No adverse effects resulting from the technique were identified. Elimination half-lives were shorter and total body clearance greater than has been reported in some pediatric studies, and in comparison with published adult data, pharmacokinetics of bupivacaine in the neonates and infants in this study are characterized by larger volumes of distribution, greater clearance, and similar elimination half-lives.

ISSN:0003-3022    

出版商:OVID    

年代:1989

数据来源: OVID