ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The effects of the calcium entry blocker diltiazem (iv loading dose 0.4 mg/kg, iv maintenance dose 0.4 mg/min) and subsequent isoflurane-induced hypotension to mean aortic pressures of 70 and 55 mmHg on global and regional right ventricular (RV) and left ventricular (LV) performance (ultrasonic dimension technique), on coronary (electromagnetic flow probes) and systemic hemodynamics, and on electrophysiologic parameters (PR, QRS, QTcintervals) were studied in eight open-chest dogs, anesthetized and paralyzed by continuous infusions of fentanyl and pancuronium. Diltiazem at a plasma concentration of 282 ± 33 ng/ml (mean ± SE) caused significant (P < 0.05) increases in coronary blood flows, and decreases in coronary and systemic vascular resistances with only little effect on global and regional RV and LV function. However, the PR interval increased by 40%, and three animals developed II° atrioventricular block type I. At stable diltiazem plasma levels, administration of isoflurance caused dose-dependent decreases in myocardial segment shortening and stroke volume with unchanged LV or increased RV preload, and little changed RV or reduced LV afterload indicating myocardial depression. Coronary and systemic vascular resistances remained unaffected. At the higher concentration of isoflurane (mean inspired 1.3 ± 0.2%), seven animals developed intermittent sinus node arrests with pauses up to 12 s followed by intermittent junctional escape or sinus rhythms. Similar interactions might develop in patients on diltiazem receiving isoflurane.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Continuous infusions of verapamil and diltiazem were established in halothane-anesthetized dogs (1.15–1.35% end tidal concentration) with or without a concomitant propranolol infusion to investigate changes: in cardiovascular function, in reflex activation as reflected in circulating catecholamine levels, and in the chronotropic response to the exogenously administered beta agonist, isoproterenol. Verapamil plasma levels of approximately 100 and 250 ng · ml-1, diltiazem plasma levels of approximately 140 and 325 ng · ml-1, and propranolol levels of approximately 70 ng · ml-1were tolerated individually in the presence of halothane, although atrioventricular conduction was prolonged in the verapamil and diltiazem groups. Catecholamine levels were increased in the high verapamil group. However, when propranolol was combined with the lower levels of verapamil or diltiazem, the result was decreased heart rate, blood pressure, left ventricular maximum rate of tension development (dP/dt), and cardiac index with increased systemic vascular resistance. When the attempt was made to proceed to the increased plasma levels of verapamil or diltiazem in the presence of propranolol, 6/6 animals in the verapamil-propranolol group and 4/6 animals in the diltiazem-propranolol group were unable to maintain a mean arterial blood pressure of greater than 50 mmHg, and many developed 2° or higher heart block. Analysis of the plots of the logarithms of the doses of isoproterenolversuschanges in heart rate revealed that larger amounts of isoproterenol were required to achieve the same increase in heart rate as with halothane alone if these plasma levels of propranolol, verapamil, or diltiazem individually were present, and that very much larger doses of isoproterenol were required to increase heart rate to the same level as with halothane alone when a combined block with verapamil or diltiazem plus propranolol was present.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Sufentanil (mean total dose 2 μ/kg) was compared with fentanyl (mean total dose 15 μ/kg) as a supplement to 60% N2O anesthesia in 30 adult patients undergoing general surgical procedures. Comparisons were made with respect to stability of hemodynamic variables (heart rate and systolic and diastolic blood pressure), changes in stress hormones (cortisol, antidiuretic hormone, epinephrine, norepinephrine, and dopamine), recovery of alertness and orientation, time to extubation, postoperative analgesia, and measures of respiratory depression (resting end-tidal carbon dioxide tension [PETCO2], CO2response curve for minute ventilation [δVE/δPETCO2]). Hemodynamic variables remained stable and similar in both groups throughout the study. Plasma hormone levels remained similar to baseline in both groups until 1 h postoperatively when epinephrine levels were significantly elevated in both groups (P< 0.05). Recovery times, including time to extubation, were similar in both groups. Patients given sufentanil had less pain 30 min post-operatively than those given fentanyl, although at 60 min postoperatively pain levels were similar in both groups. Small but significant elevations in resting PETCO2were seen in both groups postoperatively (P< 0.05), but postoperative δVE/δPETCO2responses were significantly depressed only in patients receiving fentanyl (P< 0.05). The results of this study demonstrate that sufentanil–N2O anesthesia is as effective as fentanyl–N2O in attenuating the hemodynamic and hormonal responses to the stress of general surgery. Because continuous intraoperative PETCO2monitoring was not employed in this study, intraoperative hypocapnea cannot be strictly excluded as a possible influence on the postoperative measures of ventilatory drive. However, the results of this study suggest that sufentanil–N2O results in less profound respiratory depression and greater analgesia in the immediate postoperative period after general surgery.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The pharmacokinetics of morphine in ten infants ≤ 10 weeks of age who were receiving morphine infusions were determined. Infants 1–4 days of age (newborns) showed longer elimination half-lives than the older infants (6.8vs.3.9 h). Clearance in the newborns is less than one-half that found in older infants (6.3vs.23.8 ml · min-1· kg-1). The combination of lower clearance and longer elimination half-life in newborns (0–7 days) may well explain a prolonged duration of action for morphine in very young infants, but other etiologies are needed to explain the respiratory sensitivity believed to persist in older infants.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Dogs were chronically instrumented to measure aortic and left atrial blood pressures, left ventricular maximal rate of tension development (dP/dt), cardiac output, and carotid, coronary and renal blood flows. Measurements were taken with the animals awake and during steady-state low and high concentrations of halothane (1.2%, 2.4%), enflurane (2.4%, 4.0%), and isoflurane (1.6%, 3.0%) with and without at least 2 weeks of oral verapamil, 120 mg, three times per day. Plasma verapamil levels varied widely, with means of 500–700 ng · ml-1in awake animals and lower (300–400 ng · ml-1) at the time of hemodynamic measurements during anesthesia. Chronic oral verapamil in awake dogs produced predominantly tachycardia. The hemodynamic effects of low-dose halothane and isoflurane before and after oral verapamil were unchanged except for decreased renal blood flow after oral verapamil and no coronary vasodilation nor tachycardia. However, left atrial pressure was increased and cardiac output and coronary blood flow were decreased by low concentrations of enflurane with oral verapamil compared to without. The combination of oral verapamil with low (clinical) doses of enflurane was more depressant to the cardiovascular system of healthy dogs than was the combination of verapamil and halothane or isoflurane.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The effect of iv methohexital infusion anesthesia on functional residual capacity (FRC) (helium dilution) in 14 surgical patients (age 23 to 59 years) was determined. Eight subjects were studied wearing an inflatable mask, sealed with surgical lubricant. They showed a mean ± SD 3.5 ± 6.4% FRC decrease (no significance). Six subjects studiedviamouthpiece awake andviaendotracheal tube during anesthesia showed a mean 22 ± 19% reduction in FRC, significantly greater than face mask studies (P < 0.05). The greatest FRC decrease occurred in subjects with repetitive or protracted coughing after intubation. The serum methohexital level was 6.6 ± 3.6 μg/ml for intubated patients, and 6.0 ± 1.1 μ/ml in those with face mask (no significance). The depth of anesthesia was sufficient to produce a 50% reduction in ventilatory response to CO2rebreathing, from 15.8 to 8.7 1/min/% CO2. Respitrace® plethysmography indicated a 38 ± 12% ribcage contribution to tidal volume during quiet breathing, which increased to 47 ± 14% with CO2breathing (end-tidal FCO29–10%). There was no dimunition of ribcage contribution during anesthesia in either group, irrespective of CO2concentration. The authors interpret their findings to indicate that iv methohexital anesthesia does not produce FRC reduction, in contrast to an inhaled anesthetic such as halothane. It is proposed that this difference may be related to maintenance of coordinated ribcage/diaphragm muscle activity, because ribcage activity is markedly suppressed by halothane. In addition, it is proposed that FRC reduction in intubated subjects was the result of a confounding variable, namely coughing in response to the endotracheal tube.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Six healthy, consenting volunteer males received ketamine iv in five logarithmically scaled doses totaling 3 mg/kg on three occasions each. The sessions differed only in the initial injection of an unknown drug: placebo, morphine sulfate 0.2 mg/kg, or morphine sulfate 0.4 mg/kg. Initial and terminal steady-state ventilatory responses to CO2(VERCO2) and isohypercapnic ventilation (end-tidal CO249.8 ± 2.4 mmHg) during drug administration assessed CO2-mediated ventilatory drive. Oxygen concentration of 40% ablated hypoxic drive contribution. Morphine caused a decrease of isohypercapnic ventilation (VE) of 8.2 ± 1.2 l/min after 0.2 mg/kg. Doubling the dose to 0.4 mg/kg gave a further depression of 6.6 ± 1.8 l/min. No subject lost consciousness after morphine. Over a dose range of 0.39 to 3.0 mg/kg ketamine caused log-linear dose-related depression of 1.6 ± 0.3 l/min for each doubling of dose, although the first significant depression of 4.9 ± 1.1 l/min did not occur until the third dose (1.1 mg/kg) in the absence of morphine. All subjects were unconscious after 1.8 mg/kg ketamine. Slopes of the VERCO2did not differ from control, regardless of the pretreatment, placebo, or morphine in the two doses. Ketamine alone, 3.0 mg/kg, caused a displacement of VERCO2of +2.0 ± 1.2 mmHg in CO2, while combination of ketamine and morphine in either dose caused a +10 mmHg displacement of VERCO2. Thus, ketamine appears qualitatively similar but less potent than premedicant doses of morphine in depressing respiration despite near equipotency in producing loss of consciousness.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Lung densities (atelectasis) and pulmonary gas exchange were studied in 13 supine patients with no apparent lung disease, the former by transverse computerized tomography (CT) and the latter by a multiple inert gas elimination technique for assessment of the distribution of ventilation/perfusion ratios. In the awake state no patient had clear signs of atelectasis on the CT scan. Lung ventilation and perfusion were well matched in most of the patients. Three patients had shunts corresponding to 2–5% of cardiac output, and in one patient there was low perfusion of poorly ventilated regions. CT scans after 15 min of halothane anesthesia and mechanical ventilation showed densities in dependent lung regions in 11 patients. A shunt was present in all patients, ranging from 1% in two patients (unchanged from the awake state) to 17%. Ventilation of poorly perfused regions was noted in nine patients, ranging from 1–19% of total ventilation. The magnitude of the shunt significantly correlated to the size of dependent densities (r = 0.84,P< 0.001). Five patients studied during spontaneous breathing under anesthesia displayed both densities in dependent regions and a shunt, although of fairly small magnitude (1.8% and 3.7%, respectively). Both the density area and the shunt increased after muscle paralysis. PEEP reduced the density area in all patients but did not consistently alter the shunt. It is concluded that the development of atelectasis in dependent lung regions is a major cause of gas exchange impairment during halothane anesthesia, during both spontaneous breathing and mechanical ventilation, and that PEEP diminishes the atelectasis, but not necessarily the shunt.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Minute ventilation (VE), tidal volume (VT), carbon dioxide elimination (VCO2), and end-tidal (PETCO2) and arterial CO2tensions (PaCO2) were measured in 39 anesthetized infants and children with body weights ranging from 3.1 to 31 kg. Eighteen children had normal cardiopulmonary function, seven had acyanotic congenital heart disease, and 11 had cyanotic congenital heart disease. One child had left heart failure and pulmonary congestion, and two had severe parenchymal lung disease. To evaluate differences between pulmonary gas exchange calculated from PaCO2versusPETCO2, dead space volume (VD) and alveolar ventilation (VA) based on a PaCO2(VDa, VAa) as well as on PETCO2(VDET, VAET) were performed, and correlations between PaCO2– PETCO2, VDa/VT– VDET/VT, and VAa – VAET were carried out. It was demonstrated that in normal children, as well as in those with acyanotic congenital heart disease, PETCO2correlated closely with PaCO2(r = 0.94, 0.98, respectively). In children with cyanotic congenital heart disease, however, correlation between PETCO2and PaCO2was relatively poor (r = 0.61). Mean values for PaCO2were significantly higher than PETCO2in the cyanotic children (P< 0.01), resulting in significant underestimation of physiologic dead space (P< 0.05) and significant overestimation of alveolar ventilation (P< 0.01). In three patients with pulmonary disease, large differences between PaCO2and PETCO2were comparable with those observed in the children with cyanotic congenital heart disease. It is concluded that in normal children and in children with acyanotic heart disease during anesthesia, noninvasive measurement of PETCO2can be used as a reliable estimate of PaCO2and for calculations of physiologic dead space and alveolar ventilation. In children with cyanotic congenital heart disease and severe pulmonary disease, PETCO2does not provide a precise estimate of PaCO2, and calculations of physiologic dead space and alveolar ventilation should be based on direct measurements of PaCO2.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID