ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In a double-blinded, randomized, prospective multi-center study of 695 women, we investigated whether epidural injection of sufentanil added to 0.125% bupivacaine with epinephrine (1:800,000) reduces the total amount of local anesthetic required, resulting in less motor blockade and reduced incidence of instrumental deliveries, and improves the quality of analgesia provided by this low concentration of local anesthetic without jeopardizing the safety of the baby. In addition, other potential benefits of sufentanil (such as decrease in the incidence of shivering) and side effects were examined. It was found that adding incremental doses of 10 μg sufentanil up to a maximum of 30 μg reduced the incidence of instrumental deliveries from 36 to 24% (P< 0.01) and significantly improved quality and duration of analgesia without depressing the neurobehavioral status of the baby. No other benefits from adding sufentanil were found. The only side effect that occurred more frequently after sufentanil was pruritus. We conclude that epidural injection of 10–30 μg sufentanil added to 0.125% bupivacaine with epinephrine (1: 800,000) improved the quality of analgesia during labor and reduced the incidence of instrumental deliveries without jeopardizing the safety of the baby.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

We compared the duration of action and recovery times for vecuronium in normothermic and mildly hypothermic patients. Ten patients were actively cooled to a central body temperature near 34.5° C, and ten were maintained at a normothermic central temperature (>36.5° C); temperature was measured in the distal esophagus. Vecuronium 0.1 mg/kg was administered as an intravenous (iv) bolus to all patients, and the evoked mechanical response to train-of-four stimulation was recorded. Five hypothermic and five normothermic patients were allowed to recover spontaneously. In the remaining five in each group, neostigmine (40 μg/kg) and atropine (20 μg/kg) was administered when the first twitch (T1) height spontaneously recovered to 10% of control (T1 = 10% of the prevecuronium twitch tension). Vecuronium's duration of action (from injection of drug until T1 = 10%) was 28 ± 4 and 62 ± 8 min during normothermia and hypothermia, respectively (P< 0.05). The corresponding values for spontaneous recovery from Tl = 10% to TOF ratio >75% were 37 ± 15 and 80 ± 24 min (P< 0.05), and for neostigmine-induced recovery were 10 ± 3 and 16 ± 11 min (difference not significant). We conclude that mild hypothermia increases the duration of action of and time for spontaneous recovery from vecuronium-induced neuromuscular blockade.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

This study determined whether sodium nitroprusside (SNP) changes cerebral vascular resistance during stable, hypothermic cardiopulmonary bypass (CPB). Cerebral blood flow (CBF) was measured using Xenon clearance in 39 patients anesthetized with fentanyl. In 25 patients (group 1), CBF was measured before and during infusion of SNP at a rate sufficient to reduce mean arterial pressure (MAP) ∼ 20%. In 14 other patients (group 2), CBF was measured before and during simultaneous infusion of SNP and phenylephrine; SNP was continued at a rate that had reduced MAP ∼ 20% while phenylephrine was added in a dose sufficient to restore MAP to preinfusion levels. Patients within each group were randomized to maintenance of PaCO2∼ 40 mmHg (groups la and 2a), uncorrected for body temperature, or to maintenance of PaCO2∼ 50 mmHg (groups 1b and 2b). The following variables were maintained within a narrow range: nasopharyngeal temperature (26–29° C), pump oxygenator flow (1.7–2.5 1·min-1·m-2), PaO2(150–300 mmHg), and Hct (22–28 vol%). In each patient, controlled variables varied no more than ±5% between measurements. In group la (PaCO2∼ 40 mmHg), MAP was 86 ± 9 mmHg (mean ± SD) before and 65 ± 8 mmHg during SNP infusion (P< 0.0001). CBF was 12 ± 3 ml · 100 g-1· min-1before and 10 ± 2 ml·100-1min-1during SNP infusion (P< 0.01). In group 1b (PaCO2∼ 55 mmHg), MAP was 86 ± 11 mmHg before and 66 ± 13 mmHg during SNP infusion (P< 0.0001). CBF changed from 22 ± 10 to 16 ± 6 ml ± 100 g-1· min-1(P< 0.05). In group 2a (PaCO2∼ 40 mmHg), MAP was 71 ± 10 mmHg before and 73 ± 9 mmHg during the combined SNP-phenylephrine infusion (P= not significant). CBF was 12 ± 2 ml · 100 g-1min-1before and 10 ± 1 ml · 100 g-1· min-1during the combined infusion (P< 0.05). In group 2b (PaCO2∼ 50 mmHg), MAP was 74 ± 8 mmHg before and 71 ± 4 mmHg during the combined infusion (P= ns). CBF was 18 ± 5 ml · 100 g-1min-1before and 15 ± 5 ml · 100 g-1min-1during the combined infusion (P< 0.01). The decrease in CBF was statistically similar in each group and was comparable to that previously reported to occur as a function of the duration of stable hypothermic CPB. Restoration of MAP by phenylephrine during continued SNP infusion did not result in either a relative or absolute CBF increase. During nonpulsatile, hypothermic CPB, SNP does not produce primary cerebral vasodilation in humans anesthetized with fentanyl.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The recurrent laryngeal nerve was stimulated with surface electrodes to produce vocal cord adduction, and the response was measured as pressure changes in the inflatable cuff of a tracheal tube positioned between the vocal cords. To test the linearity of the system, a model of the larynx consisting of a syringe barrel was constructed, and weights were applied to two bands of tissue simulating the vocal cords. Tests on Mallinckrodt size-7.5 tubes showed that the pressure increase produced by a given force was independent of baseline pressure in the range 10–30 mmHg. In addition, the pressure inside the inflatable cuff was linear with increasing weight (or force) for a baseline pressure of 10 mmHg. Thirty ASA physical status 1 or 2 adults were anesthetized with propofol and fentanyl. Tracheal intubation was performed in the absence of muscle relaxants, and the inflatable cuff of the tracheal tube was positioned between the vocal cords. Pressure inside the cuff was measured with an air-filled transducer. Stimulation was produced at different sites along the course of the recurrent laryngeal nerve. A surface electrode placed over the notch of the thyroid cartilage produced consistent adduction of the cords, measured as an increase of 8.9 ± 5.1 mmHg (mean ± standard deviation [SD]) in the cuff pressure. Neuromuscular blocking drugs produced train-of-four fade, and large doses abolished the response completely, ruling out direct muscle stimulation. It is concluded that this assembly can provide useful information on intrinsic laryngeal muscle function.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The differences between neuromuscular blockade of the adductor muscles of the vocal cords and the adductor pollicis were examined in 20 adult women anesthetized with fentanyl and propofol. Vecuronium 0.04 or 0.07 mg/kg was given as a single bolus by random allocation. The force of contraction of the adductor pollicis was recorded. Laryngeal response was measured as pressure changes in the cuff of the tracheal tube positioned between the vocal cords. Train-of-four stimulation was applied to the recurrent laryngeal nerve at the notch of the thyroid cartilage and to the ulnar nerve at the wrist. Neuromuscular blockade had a faster onset, was less intense, and recovered more rapidly at the vocal cords. With 0.04 mg/kg, maximum blockade of first twitch (T1) was 55 ± 8 (mean ± standard error of the mean [SEM]) and 88 ± 4% at the vocal cords and the adductor pollicis, respectively (P= 0.006). Onset time was 3.3 ± 0.1 and 5.7 ± 0.2 min, respectively (P= 0.000001), and time to 90% T1 recovery was 11.3 ± 1.6 and 26.1 ± 1.8 min, respectively (P= 0.001). With 0.07 mg/kg, onset time was unchanged; maximum blockade was more intense, being 88 ± 4 and 98 ± 1%, respectively (P= 0.04 between muscles); and time to 90% T1 recovery was 23.3 ± 4.8 min at the vocal cordsversus40.3 ± 2.9 min at the adductor pollicis (P= 0.001). Approximately 1.73 times as much vecuronium was required at the larynx compared with the dose required at the adductor pollicis for the same intensity of blockade. It is concluded that total relaxation of the vocal cords requires large doses of vecuronium, but that maximal effect is reached more rapidly than at the adductor pollicis.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Whether isoflurane has the potential to produce coronary artery steal and associated myocardial ischemia is still controversial. Previous studies addressing this issue in humans did not purposefully control hemodynamics or use continuous measures of myocardial ischemia. The authors used transesophageal echocardiography (TEE) and continuous Holter electrocardiography (ECG) to study the relative risk of myocardial ischemia during isoflurane or sufentanil anesthesia under strict control of hemodynamics in 186 high-risk patients undergoing elective coronary artery bypass graft (CABG) surgery. Overall, hemodynamics were well controlled (increased heart rate = 9.8%; increased systolic blood pressure = 7.1%; decreased systolic blood pressure = 10.8% of total prebypass time compared with preoperative baseline values), with no difference between the two anesthetics. In the 162 patients with interpretable TEE recordings, moderate to severe TEE ischemic episodes (grade change ≥ 2) developed in 33 (21%) during the prebypass period, with no difference between isoflurane (12 of 56 = 21%) and sufentanil (21 of 106 = 20%) (P= 0.97). The duration and severity of TEE episodes were not significantly different between the two groups. No correlation was observed between TEE ischemic episodes and isoflurane concentrations (range, 0.47–1.75%). In the 181 patients with interpretable ECG recordings, ECG evidence of ischemia developed in 34 (19%) during the prebypass period, with no difference between isoflurane (12 of 59 = 20%) and sufentanil (22 of 122 = 18%) (P= 0.87). The duration and severity of electrocardiographic ischemic episodes were also similar in patients receiving either isoflurane or sufentanil. Four of the 62 patients (6%) who received isoflurane had an adverse cardiac outcomeversus15 of 124 patients (12%) who received sufentanil. (P= 0.34). The authors' findings demonstrate that, when hemodynamics are controlled, the incidence of myocardial ischemia (TEE or ECG) during isoflurane and sufentanil anesthesia is similar.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Perioperative myocardial ischemia is associated with an increased risk of perioperative myocardial infarction (PMI). Several attempts have been made to define intraoperative hemodynamic predictors of myocardial ischemia. In a canine preparation with coronary stenosis, a pressure rate quotient (PRQ = mean arterial pressure/heart rate) less than one (PRQ < 1) indicated subendocardial myocardial ischemia. The authors tested this hypothesis in patients undergoing elective coronary artery bypass graft operation (CABG), using electrocardiogram (ECG) ST-segment changes (leads II/V5) to diagnose myocardial ischemia. Sixty (n = 60) patients having CABG surgery were prospectively studied before initiation of cardiopulmonary bypass. Calibrated ECG leads II and V5(diagnostic mode) were monitored continuously and recorded with the use of a Hewlett-Packard computer ST-segment analyzer. In addition, arterial and pulmonary artery pressures were monitored. Ischemia was defined asnew-onset ST deviation (≥1 mm from the baseline ECG). ECG and hemodynamic data were stored at 2-min intervals for subsequent computer analysis. Serial creatinine phosphokinase (CPK) X MB (%) determinations and 12-lead ECGs were collected for the initial 3 postoperative days. Of the 3,463 intervals (2 min) available for study, 3,322 (96%) were satisfactorily recorded for 60 patients. Ischemia occurred during 65 intervals in 9 patients (9 of 60), of which only 34% (22 of 65) were associated with a PRQ < 1 (P< 0.01). In contrast, there were 466 intervals during which PRQ was less than 1, but without ECG evidence of ischemia. Four (4 of 60) patients had PMIs, but in only 1 (1 of 4) was pre-CPB ischemia associated with a PRQ < 1. The authors conclude that PRQ < 1 is an insensitive indicator and predictor of myocardial ischemia in patients undergoing elective CABG.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Transesophageal atrial pacing (TAP) with the use of standard, thermistor-equipped, esophageal stethoscopes, modified for pacing by incorporation of a 4-French, bipolar TAP probe (pacing esophageal stethoscope [PES]), was evaluated in 100 adult patients under general anesthesia. A commercially available TAP pulse generator supplied 10-ms pulses with current variable between 0 and 40 mA. Pacing distances (in centimeters) were measured from the infraal-veolar ridge to midway between PES electrodes (1.5-cm interelectrode distance). Pacing thresholds (milliamperes) were measured at the point of a maximum-amplitude P-wave (PMAX) in the bipolar esophageal electrogram and points 1 cm proximal or 1, 2, or 3 cm distal to PMAXTAP (70–100 beats per min) was used for sinus bradycardia ≤ 60 beats per min (36 patients) or atrioventricular (AV) junctional rhythm (2 patients) and blood pressure changes with TAP documented. In male patients (n = 49), PMAXwas 32.7 ± 0.3 cm (mean ± SE) and minimum pacing threshold 5.1 ± 0.4 mA (range, 1–13 mA) at 33.6 ± 0.3 cm (range, 30–37 cm). In female patients (n = 51), PMAXwas 30.4 ± 0.4 cm and minimum pacing threshold 4.4 ± 0.4 mA (range, 2–14 mA) at 31.1 ± 0.4 cm (range, 26–40 cm). TAP produced an average 13–16 mmHg increase in systolic, diastolic, or mean-arterial pressure in patients with sinus bradycardia or AV junctional rhythm. There were no subjective patient complaints (epigastric discomfort, dysphagia) that could be attributed to TAP; objective evaluation (esophagoscopy) was not performed. It is concluded that TAP is widely applicable to anesthetized adults; low TAP thresholds can be obtained by first determining PMAXand positioning the PES electrode 1 cm or less distal to PMAX; and TAP can be used to increase blood pressure in patients with sinus bradycardia or AV junctional rhythm.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The effect of isoflurane-induced hypotension on glomerular function and renal blood flow was investigated in 20 human subjects. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by inulin and paraaminohippurate (PAH) clearance, respectively. Anesthesia was maintained with fentanyl, nitrous oxide, oxygen, and isoflurane. Hypotension was induced for 236.9 ± 15.1 min by increasing the isoflurane inspired concentration to maintain a mean arterial pressure of 59.8 ± 0.4 mmHg. GFR and ERPF decreased with the induction of anesthesia but not significantly more during hypotension. Postoperatively, ERPF returned to preoperative values, whereas GFR was higher than pre-operative values. Renal vascular resistance increased during anesthesia but decreased when hypotension was induced, allowing the maintenance of renal blood flow. We conclude that renal compensatory mechanisms are preserved during isoflurane-induced hypotension and that renal function and hemodynamics quickly return to normal when normotension is resumed.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID