摘要:

The efficacy of intravenous (iv) and epidural infusions of alfentanil for postoperative pain relief was investigated in 24 patients (ASA physical status 1–2) who were scheduled for abdominal hysterectomy. The patients were allocated randomly to receive either epidural or iv alfentanil. In both groups, a loading dose of 15 μg·kg-1was administered, followed by a constant rate infusion of 18 μg·kg-1. h-1alfentanil for 20 h. Both routes provided similar degrees of analgesia; however, analgesia occurred earlier in the intravenously treated group (P< 0.03). Mean plasma alfentanil concentrations (Cps) varied between 42 and 82 ng·ml-1in the iv group and 23 and 68 ng·ml-1in the epidural group, with higher concentrations in the iv group for the first 60 min only (P< 0.01). Cpsincreased with infusion time, suggesting accumulation of alfentanil. After infusion ended, pain recurred at the same time in both groups, whereas the alfentanil Cpsstill were greater than 45 ng/ml. Postoperative epinephrine concentrations decreased after 60 min of infusion (P< 0.02), whereas, after 6 h, cortisol levels decreased to preoperative values. Norepinephrine concentrations decreased only slightly. The only clinically meaningful effect on vital signs that occurred was an abrupt reduction of respiratory rate after the iv loading dose. Paco2increased to the same extent in both groups during the first 15 min only. The incidence of opioid-related side effects was similar in both groups. These results suggest that the iv and epidural routes were equally effective for providing postoperative pain control and controlling the postoperative response to surgical stress.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Flumazenil, a benzodiazepine antagonist, reliably reverses midazolam-induced sedation; however, its effect on respiratory depression has not been established completely. Twelve healthy volunteers received sufficient midazolam (0.13 ± 0.01 mg·kg-1mean ± SE) to render them unresponsive to verbal command; they then received flumazenil 1.0 mg or placebo (flumazenil vehicle) in a randomized, double-blind fashion. Ventilatory drive was measured before and after administration of midazolam, as well as 3, 30, 60, and 120 min after administration of flumazenil or placebo. Seven to 30 days later, the study was repeated, with subjects receiving placebo or flumazenil (whichever they had not received during their first trial). Midazolam caused significant decreases in the slope of the CO2response (-29 ± 5%;P< 0.005); minute ventilation (VE) at end-tidal CO2tension (PETco2) = 46 mmHg (-28 ± 4%;P< 0.001), and tidal volume at PETco246 mmHg (-44 ± 4%;P< 0.005). Three minutes after intravenous administration of flumazenil 1.0 mg, VE46 and tidal volume increased to 108 ± 6% and 105 ± 6%, respectively, of their premidazolam values; at the same time after administration of placebo, VE46 and tidal volume remained significantly depressed (between groups,P< 0.005 for each variable). Thirty minutes later, these variables did not differ between groups, probably because the effects of flumazenil and midazolam were diminishing. Neither flumazenil nor placebo affected the slope of the CO2response, which remained significantly (P< 0.05) less than premidazolam values for 2 h after both treatments; this variable never differed between groups. By virtue of its ability to reverse some components of midazolaminduced ventilatory depression, flumazenil may help improve resting ventilation in patients who have received midazolam.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The purpose of this study was to determine the contribution of nitrous oxide to isoflurane MAC in pediatric patients. MAC was determined in 47 infants and small children (mean ages 16.6 ± 6.7 months) during isoflurane and oxygen anesthesia (n = 11) and isoflurane and nitrous oxide anesthesia (25% nitrous oxide [n = 12], 50% nitrous oxide [n = 12], and 75% nitrous oxide [n = 12]). After assigning patients to one of four groups, anesthesia was induced with increasing inspired concentrations of isoflurane in oxygen. After anesthetic induction and tracheal intubation, ventilation was controlled (carbon dioxide partial pressure = 32 ± 5 mmHg), and nitrous oxide was added to the inspired gas mixture to achieve endexpired nitrous oxide concentrations of 0, 25, 50, or 75%. Inspired and expired gas samples were obtained from a distal sampling port in the tracheal tube. The response to skin incision in each patient was assessed at a previously selected end-tidal concentration of isoflurane. The MAC of isoflurane was determined in each group using the up-and-down method described for evaluating quantal responses. The mean duration of constant end-tidal concentrations prior to skin incision was 14 ± 7 min (range 6–46 min). The ratio of expired to inspired nitrous oxide and isoflurane concentrations during the period of constant end-tidal concentrations was 0.96 ± 0.01 and 0.93 ± 0.03 respectively. The MAC of isoflurane in oxygen was 1.69 ± 0.13 vol % (mean ± standard deviation). The MAC of isoflurane in the presence of 25, 50, and 75% nitrous oxide was 1.26 ± 0.10, 0.97 ± 0.10, and 0.58 ± 0.09 vol %, respectively. As the concentration of nitrous oxide increased, the MAC of isoflurane decreased linearly (r2= 0.93). The predicted MAC of nitrous oxide in children was 109 ± 5 vol %, a value similar to the predicted MAC of nitrous oxide in prior studies of adults.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In searching for a nondepolarizing muscle relaxant with intermediate duration but more rapid onset of action than the presently available compounds, the neuromuscular and circulatory effects of ORG9426 were investigated in two studies in humans receiving fentanyl, droperidol, thiopental, and nitrous oxide–oxygen anesthesia. Eighty patients, randomly assigned to one of four groups of 20 each, received 0.12, 0.16, 0.20, or 0.24 mg/kg ORG9426. In the first study, the doses (in milligrams per kilogram) of ORG9426 that caused 50% (ED50), 90% (ED90), or 95% (ED95) neuromuscular block were determined by the individual dose-response method; they were 0.170, 0.268, and 0.305 mg/kg, respectively. In the second study, after induction of anesthesia, patients received 0.6 mg/kg (about 2 X ED95) of ORG9426, either in a single bolus (group 1) or in two unequal (0.1 and 0.5 mg/kg) increments 4 min apart (group 2). After the administration of 0.6 mg/kg ORG9426, maximal neuromuscular block developed in 1.5 ± 0.12 min in group 1 and in 1.2 ± 0.14 min in group 2. Patients tracheas were intubated after development of the maximal neuromuscular effect of the intubating dose and after the recording of heart rate and systolic and diastolic blood pressure. There was no difference in the clinical duration of the intubating doses, which were 40.0 ± 3.2 (15–73) min in group 1 and 39.3 ± 2.4 (19–57) min in group 2. Clinical duration of the first repeat dose of 0.1, 0.15, or 0.2 mg/kg ORG9426, administered whenever the twitch tension elicited by the first train-of-four impulse recovered to 25% of control were 11.0 ± 1.0 (4–16), 18.3 ± 1.6 (7–50), and 28.1 ± 6.3 (7–69) min, respectively. The recovery index was 16.7 ± 1.2 (4–64) min. In 89 patients residual neuromuscular block at the end of anesthesia could be antagonized with 0.5 mg/kg edrophonium†0.015 mg/kg atropine in 2 to 5 min. No circulatory or other side effects attributable to ORG9426 and no signs or symptoms of recurrent paralysis were observed in the postanesthetic recovery room. The onset time of ORG9426 was shorter than those of other nondepolarizing muscle relaxants previously studied in identically anesthetized patients. “Priming” did not shorten the onset time of 2 X ED95ORG9426. Because of its rapid onset of action, of the currently available nondepolarizing muscle relaxants, ORG9426 may prove useful for facilitating rapid sequence intubation.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Desflurane's induction and recovery characteristics were compared to those of propofol–nitrous oxide in outpatients undergoing laparoscopic procedures. Ninety-two healthy patients were randomized to receive either: 1) propofol induction and propofol-nitrous oxide maintenance (control), 2) propofol induction and desfluranenitrous oxide maintenance, 3) desflurane–nitrous oxide, or 4) desflurane alone for induction and maintenance of anesthesia. Inhalational induction with desflurane–nitrous oxide was faster than with desflurane alone (100 ± 35vs.124 ± 43 s). Inhalation inductions were associated with a high incidence of apnea (17 and 26%), breathholding (26 and 39%), and coughing (30 and 22%) in groups 3 and 4, respectively. The emergence time after discontinuation of desflurane in oxygen (4.5 ± 2.1 min.) was significantly less than that after propofol–nitrous oxide (7.3 ± 3.9 min.). However, times from arrival in the recovery room until the patients were judged fit for discharge were similar for all four treatment groups. Digit–symbol substitution test results and sedation visual analogue scores also were similar during the first 2 h in the recovery room. A lower incidence of moderate-to-severe nausea was reported in group 1 (15%vs.52, 52, and 59% in groups 2, 3, and 4, respectively). In conclusion, induction of anesthesia with desflurane was rapid but is associated with a high incidence of airway irritation. Emergence and recovery profiles after maintenance of anesthesia with desflurane compared favorably to a propofol–nitrous oxide combination. However, propofol was associated with a lower incidence of nausea than was desflurane after outpatient anesthesia for laparoscopic surgery.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Vomiting is a common problem after strabismus surgery in pediatric outpatients. We compared the effects of propofol with and without N2O and droperidol to the effects of a conventional regimen consisting of halothane–N2O–droperidol on the recovery characteristics and the incidence of postoperative emesis after strabismus surgery in 120 ASA physical status 1 or 2 children. After induction of anesthesia with halothane–N2O, patients were randomly assigned to one of four groups. Group A (control) received halothane, 66% N2O, and droperidol 75 μ·kg-1; group B, propofol 2 mg·kg-1bolus followed by infusion of 160 μ·kg-1min-1; group C, propofol (as in group B) and 66% N2O; and group D, propofol (as in group B), 66% N2O (as in group C), and droperidol 75 μ·kg-1. Patients in group B had more episodes of intraoperative oculocardiac reflex responses than patients in group A, but had shorter times to extubation, oral intake, ambulation, and discharge, as well as a lower incidence of postoperative emesis (P< 0.05). The addition of N2O to the propofol anesthetic regimen (group C) was associated with an increased incidence of emesis (P< 0.05), whereas the addition of droperidol to the propofol–N2O regimen (group D) did not affect the incidence of emesis compared to the other three groups. We conclude that maintenance of anesthesia with a total intravenous regimen using propofol results in a more rapid recovery and less postoperative emesis than with a halothane–N2O–droperidol regimen.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In right-to-left (RL) intracardiac shunting, the venous blood that is added to the oxygenated blood in the left heart is both poor in oxygen and rich in carbon dioxide. Thus, any given degree of arterial desaturation is associated with an obligatory arterial to end-tidal carbon dioxide tension difference (Paco2– PETco2). This paper presents a theoretical analysis of the relationship between Paco2– PETco2and arterial hemoglobin saturation (Sao2) in cyanotic heart disease. Using the shunt equation as a starting point, a curvilinear, negative correlation between Paco2– PETco2and Sao2, can be demonstrated. The slope of the regression of Paco2– PETco2against Sa02is shown to be positively correlated to Hb concentration, Paco2, and the respiratory quotient R. The slope of the regression is also slightly increased at relatively high Sao2s and at high inspired oxygen fractions, although these latter factors are of lesser significance. However, in addition to the above primary effects of RL shunting, secondary effects may occur if pulmonary perfusion is reduced sufficiently to cause “alveolar hypoperfusion,” which also creates an alveolar dead space. Primary and secondary effects are additive. This theoretical analysis is illustrated with a study of 27 children with congenital heart disease. Their lungs were ventilated with a Servoventilator 900 C, and carbon dioxide single-breath tests were obtained on-line with the use of a computerized system based on the Siemens-Elema carbon dioxide analyzer 930. Blood was sampled for Paco2measurement and arterial Hb saturation was measured by pulse oximetry (Spo2). The relationship between Paco2– PETco2and Spo2, was found to agree with that predicted by theory, confirming that in cyanotic heart disease, Paco2– PETco2increases by 0.2–0.4 kPa (2–3 mmHg) for every 10% reduction in Spo2. Awareness of this relationship is necessary when attempting to estimate Paco2from PETco2, during anesthesia in cyanotic children.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Clonidine, recently introduced into anesthesia practice, may cause bradycardia. Whether this bradycardia is reversible with atropine is not known. Accordingly, we studied heart rate (HR) responses to intravenous atropine in 80 patients assigned randomly to either a control group, who received no medication (n = 20), or a clonidine group, who received oral clonidine of approximately 1.2 μg.kg-1(n = 20), 2.5 μg.kg-1(n = 20), or 5 μg.kg-1(n = 20). All patients received incremental doses of atropine, 2.5, 2.5, and 5 μg.kg-1, at 2-min intervals (total dose 10 μg.kg-1). Positive chronotropic response to the cumulative atropine dose of 10 μg.kg-1was attenuated significantly only in patients given clonidine 5 μg·kg-1(7 ± 1 beats per min, mean ± standard error) when compared with those given smaller doses of clonidine (15 ± 2, 16 ± 2 beats per min) or no clonidine (19 ± 2 beats per min) (P< 0.05). To determine whether HR hyporesponsiveness to atropine induced by clonidine can be overcome by a larger dose of atropine, the authors studied 30 additional patients given clonidine 5 μg·kg-1or no medication. In all patients not receiving clonidine (n = 15), HR increased by more than 20 beats per min when atropine of 15 μg·kg-1was administered, whereas in only 5 patients (33%) receiving clonidine did the HR increase by 20 beats per min after atropine 15 μg.kg-1(P< 0.001). Furthermore, only slight increases in HR were noted in 4 of 15 patients given clonidine medication (26%) even after the administration of atropine 40 μg·kg-1. It is concluded that the HR response to intravenous atropine is attenuated in awake humans receiving oral clonidine of 5 μg·kg-1. The decreased responsiveness to atropine in patients receiving clonidine 5 μg·kg-1cannot be effectively overcome in all patients by a larger dose of atropine.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Oral transmucosal fentanyl citrate (OTFC) is a novel, noninvasive dosage form of fentanyl used to provide children and adults with sedation, anxiolysis, and analgesia. In order to determine the bioavailability and absorption of fentanyl from OTFC, 12 volunteers were given intravenous fentanyl citrate or OTFC 15 μg/kg on each of two occasions. On a third occasion, the authors assessed oral administration (gastrointestinal absorption) by giving eight of the same volunteers the same dose of a solution of fentanyl citrate to swallow. In each study, arterial blood samples were taken over 24 h for analysis of plasma fentanyl. After intravenous (iv) administration of fentanyl, clearance (mean ± standard deviation) was 0.67 ± 0.15 1/min; volume of distribution at steady state was 287 ± 79 1; and the terminal elimination half-life was 425 ± 102 min. Peak plasma concentrations of fentanyl were higher (3.0 ± 1.0vs.1.6 ± 0.6 μg/ml,P= 0.01) and occurred sooner (22 ± 2.5vs.101 ± 48.8 min,P= 0.003) after OTFC than after oral solution administration. Plasma concentrations of fentanyl after OTFC decreased rapidly, to less than 1.0 ng/ml within 75–135 min after the beginning of administration. Peak absorption rate was greater (11.1 ± 4.3vs.3.6 ± 2.1 μg/min,P= 0.004) and occurred much sooner after OTFC than after oral solution administration (19 ± 2.6vs.87.5 ± 38.1 min,P= 0.001). Systemic bioavailability was greater after OTFC administration than after the oral solution (0.52 ± 0.1vs.0.32 ± 0.1,P= 0.01). Terminal elimination half-life was similar after all modes of fentanyl delivery–OTFC (460 ± 313 min), iv (425 ± 102 min), or oral solution (469 ± 123 min). These results suggest that although absorption of fentanyl from OTFC occurs through both the oral mucosa and the gastrointestinal tract, it is more rapid at the former. The data also indicate that sequestration of fentanyl in the oral mucosa is minimal.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Recently, we described a basic model and its more elaborate variants to predict the uptake and distribution of inhalational anesthetics during closed-circuit anesthesia. As an initial clinical validation of the linear, continuous, 14-compartment basic model, the current study examined its predictive performance in 50 patients by comparing quantitatively the predicted and the measured alveolar concentration-time profiles after bolus injections of liquid isoflurane into the closed system during mechanical ventilation. The two versions of the model studied differed in the size of their peripheral shunt, as 0% (version A) and 16% (version B) of the cardiac output. A total of 15,744 alveolar concentrations of isoflurane (one per 10s period) were measured by mass spectrometry. For each measured concentration we used computer simulations of version A and version B to calculate a predicted concentration for both versions. For each patient we calculated the bias (indicating over- or underprediction) and the scatter of the prediction errors (indicating the typical error size). The bias and the scatter of the prediction errors, both given as mean (and standard deviation), were 2.25 (13.59) and 12.51 (5.84)% for version A and 12.00 (14.97) and 14.12 (6.54)% for B. Version A performed better than B: both the bias (P= 0.008) and the scatter (P< 0.0001) were closer to zero for A. Logistic regression analysis showed for version A that scatter, but not bias, increased with age (P= 0.002). Gender, body mass index (weight·height-2), and number of injections per hour did not influence scatter or bias. The results indicate that version A is sufficiently accurate to be used for clinical, teaching, research, economic, and ecological purposes.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID