ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Intravenous magnesium supplementation is often used to control cardiac arrhythmias and coronary artery vasospasm resulting from disturbances of magnesium homeostasis after coronary artery bypass surgery. Many such patients also require inotropic drug support of depressed myocardial function. However, increased serum magnesium concentrations directly depress cardiac contractility in animals and may interfere with catecholamine actions. To determine whether small intravenous doses of magnesium sulfate (MgSO4) interfere with the cardiotonic actions of epinephrine, we examined the hemodynamic effects of MgSO4and epinephrine infusion in 17 cardiac surgical patients on their 1st postoperative day in a prospective, controlled study. In 11 patients, infusion of MgSO4(7-mg kg−1bolus followed by 10 mg-kg−1·h−1as a continuous infusion) increased serum magnesium concentrations by 44% (mean ± standard error of the mean [SEM] of 0.8 ± 0.1 to 1.2 ± 0.1 mM;P< 0.01) but had no significant effect on heart rate; mean arterial, central venous, or pulmonary arterial occlusion pressures; or cardiac output. Epinephrine infusion (30 ng·kg−1·min−1) significantly increased cardiac index (2.7 ± 0.1 to 3.1 ± 0.2 1·min−1·m−2;P< 0.05); this effect was not altered by MgSO4administration (n = 11). However, MgSO4significantly blunted epinephrine's hypertensive action and prevented a significant increase in mean arterial pressure during concurrent MgSO4-epinephrine administration. Six placebo control patients were given two sequential infusions of epinephrine separated by a placebo infusion to rule out an effect of time on the hemodynamic response to epinephrine. Mean arterial pressure and cardiac index responses to epinephrine were identical before and after placebo infusion. We conclude that infusion of the small doses of MgSO4after coronary surgery to treat arrhythmias and vasospasm attenuates the vasoconstrictor actions of epinephrine but has no effect on epinephrine's cardiotonic activity.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

This single-blind study examined four levels of monitoring in 402 pediatric cases. Patients were randomly assigned to one of four groups: 1) oximeter and capnograph; 2) only oximeter; 3) only capnograph; or 4) neither oximeter nor capnograph data available to the anesthesia team. An anesthesiologist, not involved in patient care, observed all cases and continuously recorded hemoglobin oxygen saturation (Spo2), ECG, expired CO2, and the oximeter plethysmographic output. Mean age, weight, ASA physical status, airway management (mask or endotracheal tube), and anesthetic technique were similar in each group. Two-hundred sixty problems were documented in 153 patients. Fifty-nine events in 43 patients resulted in “major” desaturation (Spo2≤ 85% for ≥ 30 s). Fifteen “major” capnograph events (esophageal intubation, disconnection, accidental extubation, or obstructed endotracheal tube) were observed in 11 patients; 8 of these also developed varying degrees of desaturation. One-hundred thirty “minor” desaturation events (Spo2≤ 95% for ≥ 60 s) and 79 “minor” capnograph events (hypercarbia or hypocarbia) were observed. A number of problems fulfilled criteria in multiple categories. Infants ≤ 6 months of age had the highest incidence of major desaturation events (18 of 65 [27%]) compared to toddlers 7–24 months of age or children >24 months of age (P< 0.001). Blinding the oximeter data increased the number of patients (12vs.31) experiencing major desaturation events (P= 0.003); blinding the capnograph data altered neither the frequency of desaturation events nor the incidence of major capnograph events. Blinding the capnograph data increased the number of patients with minor capnograph events (22vs.47;P= 0.0026). More patients experienced multiple problems when neither capnograph nor oximeter data were available compared to when both were available (23 as. 11;P= 0.04). We conclude: 1) The pulse oximeter is far superior to either the capnograph or clinical judgment in providing the earliest warning of desaturation events. 2) Capnography can provide an early warning to potentially life-threatening problems, but such problems often result in desaturation. 3) Capnography reduces the incidence of hypercarbia and hypocarbia. 4) Infants ≤ 6 months of age are at greatest risk for major desaturation and major capnograph events. 5) The number of problems observed can be significantly reduced when both monitors are used.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Desmopressin acetate is used to reduce blood loss after cardiac surgery. However, there have been reports that hypotension can occur with infusion of desmopressin and that postoperative blood loss is not reduced. In this randomized, double-blinded study, we investigated the effects of desmopressin on hemodynamics, coagulation, and postoperative blood loss in patients undergoing primary elective coronary artery bypass grafting (CABG). After reversal of heparin effect, 20 patients received desmopressin 0.3 μg-kg−1, infused over 15 min, and 20 patients received a placebo. Desmopressin produced a small but significant decrease in diastolic blood pressure when compared with the placebo (50.8 mmHgvs.57.6 mmHg for the desmopressin- and placebo-treated groups, respectively;P= 0.0372). A 20% or greater decrease in mean arterial pressure was observed in 7 of 20 patients receiving desmopressin, whereas only one patient in the placebo-treated group experienced a decrease of this magnitude (P= 0.0177). Reductions in arterial pressure were secondary to decreases in systemic vascular resistance (SVR) (mean SVR before and after the drug infusion, 1,006 and 766 dyn s cm−5, respectively, for the desmopressin-treated group; and 994 and 1,104 dyn s cm−5, respectively, for the placebo-treated group;P= 0.0078). In addition, desmopressin did not reduce postoperative blood loss (mean 24-h mediastinal blood loss, 790 mlvs.687 ml for the desmopressin- and placebo-treated groups, respectively), improve the postoperative bleeding time (mean times of 8.3 minvs.9.0 min for the desmopressin- and placebo-treated groups, respectively), or enhance coagulation (mean prothrombin time, 14.2 svs.13.5 s and, mean partial thromboplastin time, 46.0 svs.45.5 s for desmopressin-and placebo-treated groups, respectively) in patients undergoing primary CABG. The authors conclude that intravenous infusion of desmopressin reduces SVR, often leading to hypotension, and does not reduce postoperative blood loss in patients having uncomplicated CABG.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The effects of two doses of dexmedetomidine (0.3 or 0.6 μg kg−1), fentanyl 2.0 μg kg−1, or saline as a single intravenous bolus administered 10 min prior to the induction of anesthesia were assessed in double-blind, randomized study in 96 women undergoing abdominal hysterectomy. In each patient, anesthesia was induced with thiopental 4.0 mg kg−1, and after the effect of succinylcholine had dissipated, isoflurane 0.3% end-tidal concentration in 70% nitrous oxide was begun to maintain anesthesia. The isoflurane concentration was adjusted to maintain blood pressure and heart rate within 20% of preoperative values, and fentanyl was given if the end-tidal isoflurane concentration exceeded 1.5%. In all groups, blood pressure and heart rate increased after tracheal intubation. However, the increase in blood pressure and heart rate was significantly less in the higher dexmedetomidine (0.6 μg kg−1) group than in the saline group (P< 0.01). Also, the postintubation increase in heart rate was significantly less (P< 0.05) in the dexmedetomidine 0.6 μg kg−1group (increase of 18 ± 3 beats per min) compared to the fentanyl group (increase of 26 ± 3 beats per min). In patients receiving dexmedetomidine 0.3 μg-kg−1, the increase in blood pressure or heart rate did not differ from that of the saline group. The mean end-tidal isoflurane concentration was significantly less in the women receiving the higher dose of dexmedetomidine (0.35%) than in those receiving saline (0.47%) or fentanyl (0.48%), although the reduction was not clinically important Thus, a single intravenous bolus dose of dexmedetomidine 0.6 μ·kg−1, given before the induction of anesthesia, reduced the increase in heart rate in response to tracheal intubation and diminished isoflurane requirements during abdominal hysterectomy, when compared to that required by patients receiving fentanyl 2.0 mg·kg−1. The clinical importance of these effects is unclear and must await studies in patients having more significant cardiovascular disease.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

To examine the association between anemia and postoperative apnea in former preterm infants, 24 former preterm infants of less than 60 weeks postconceptual age undergoing inguinal hernia repair were studied. A hematocrit of at least 25% was required for study participation. General endotracheal inhalational anesthesia, supplemented with neuromuscular blockade and controlled ventilation, was used. No barbiturates or opioids were administered. Respiratory pattern and heart rate were recorded for at least 12 h postoperatively using an impedance pneumograph. Tracings were analyzed for evidence of apnea, periodic breathing, and/or bradycardia by a pulmonologist unaware of the hematologie profile of the infant. Nineteen patients had a hematocrit of 30% or greater (group 1). Their mean (± standard deviation [SD]) gestational age was 33.5 ± 2.7 weeks and postconceptual age 45.5 ± 4.6 weeks. Five infants had a hematocrit less than 30% (group 2). Their mean gestational age (± SD) was 32.4 ± 3.2 weeks and postconceptual age 43.6 ± 5.5 weeks. Anemic infants had an 80% incidence of postoperative apneaversus21% in infants with a normal hematocrit (P< .03). In the infants who developed postoperative prolonged apnea and/or bradycardia, a prior history of apnea was equally present in both groups (21% in group 1 and 20% in group 2). This study shows that anemia in former preterm infants can be associated with an increased incidence of postoperative apnea.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Patients who cannot be separated from mechanical ventilation (MV) after an episode of acute respiratory failure often have coexisting coronary artery disease. The authors hypothesized that increased left ventricular (LV) wall stress during periods of spontaneous ventilation (SV) could alter myocardial perfusion in these patients. Using thallium-201 (201TI) myocardial seintigraphy, the authors studied the occurrence of myocardial perfusion abnormalities during periods of SV in 15 MV-dependent patients (nine women, six men; aged 71 ± 7 yr, mean ± SD). Fourteen of these patients were studied once with201TI myocardial seintigraphy during intermittent mechanical ventilation (IMV) and again on another day, after at least 10 min of SV through a T-piece. One patient was studied during SV only. Thirteen of 14 of the patients (93%) studied during MV had abnormal patterns of initial myocardial201TI uptake, but only 1 patient demonstrated redistribution of201TI on delayed images. The remainder of the abnormalities observed during MV were fixed defects. SV produced significant alterations of myocardial201TI distribution or transient LV dilation, or both, in 7 of the 15 patients (47%). Four patients demonstrated new regional decreases of LV myocardial thallium concentration with redistribution of the isotope on delayed images. The patient studied only during SV also had myocardial201TI defects with redistribution. Five patients (3 also having areas of201TI redistribution) had transient LV dilation during SV. The change from MV to SV was accompanied by increased spontaneous minute ventilation (3.5 ± 2.6 to 8.4 ± 3.7 1/min) and mean arterial blood pressure (90 ± 2 to 98 ± 3 mmHg), and decreasedpHa(7.41 ± 0.02 to 7.37 ± 0.03) (P< 0.05 by pairedttest for each comparison); the Pao2, Paco2, heart rate, 12-lead ECG, tidal volume, vital capacity, and maximum inspiratory pressure were unchanged. The frequent occurrence of new regions of altered myocardial201TI uptake and LV dilation during SV suggests that myocardial perfusion often is altered and myocardial ischemia may be present during SV in MV-dependent patients.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Whether or not intravenous glucose administration during pediatric anesthesia is necessary remains a controversial issue. The current study was designed to investigate the effect of glucose infusion on concentrations of plasma glucose, nonesterified fatty acids (NEFA), triglycerides, ketone bodies, and insulin and to determine whether the use of solutions containing less than 5% glucose would maintain physiologic plasma glucose concentrations during tympanoplasty lasting about 6 h. Forty-five children aged between 1.5 and 9 yr were divided randomly into three groups of 15 patients each to receive the following intravenous solutions: LR group, lactated Ringer's solution (LR) alone; D2LR group, 2% glucose in LR; and D5LR group, 5% glucose in LR. All fluids were infused at a rate of 6 ml · kg−1· h−1until 1 h after anesthesia. In the LR group, the plasma glucose concentrations remained unchanged perioperatively compared with basal values, whereas in the D2LR group they showed a gradual increase during surgery but remained normoglycemic. On the other hand, in the D5LR group, the plasma glucose concentrations increased markedly both during and after the operation. Furthermore, 3 of 15 patients showed hyperglycemia of more than 300 mg · dl−1during anesthesia. There was no evidence of lipid mobilization or impaired secretion of insulin, since plasma NEFA, triglycerides, ketone bodies, and insulin remained within normal concentration ranges throughout the sample period in the three groups. These data indicate the possibility that even in uncomplicated pediatric surgery of long duration, intravenous infusion of glucose at a concentration of 2% and less may be sufficient to maintain plasma glucose concentrations within physiologic ranges and to prevent compensatory increase in lipid mobilization (lipolysis) when fluids are infused at a rate of 6 ml · kg−1· h−1. Extrapolation of the results to the general population is limited because of the small number of patients and the limited age range studied.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Sixty unpremedicated outpatients undergoing elective extracorporeal shock wave lithotripsy using an unmodified Dornier HM-3 lithotriptor were randomly assigned to receive an intravenous infusion of either alfentanil or ketamine as an adjuvant to midazolam for sedation and analgesia. Although both drug regimens allowed the maximal number of shock waves and energy level, the alfentanil group had significantly better calculi fragmentation (78%vs.50% of patients with fragments < 2 mm). Ketamine infusion provided superior intraoperative cardiorespiratory stability; however, it was associated with more disruptive movements (22vs.5) and dreaming (35%vs.5%) during the procedure (P< 0.05). Postoperatively, confusion also occurred more frequently in the ketamine-treated patients (31%vs.5%,P< 0.05). Alfentanil infusion was associated with more episodes of hemoglobin oxygen desaturation to < 90% (12vs.2,P< 0.05), itching (23%vs.4%,P< 0.05), and ability to recall intraoperative events (45%vs.12%,P< 0.05). The incidence of postoperative nausea was decreased (not significantly) in the alfentanil group (32%vs.54%). The mean anesthesia time was similar in both groups; however, discharge times (means ± standard deviations) were-shorter in the alfentanil group (142 ± 42 minvs.161 ± 31 min,P= 0.05). These data suggest that although both techniques proved effective for anesthesia in outpatients undergoing immersion lithotripsy, alfentanil is superior to ketamine as part of a sedative-analgesic technique because of the improved recovery profile and calculi fragmentation.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

To test the hypothesis that increasing levels of epidural analgesia will produce progressive decreases in circulating catecholamines, we sequentially produced three levels of analgesia, T8, T4, and C8, to pin prick in young, healthy volunteers. Three percent chloroprocaine (plain) was used as the local anesthetic. The epidural analgesia was allowed to dissipate following the T8 and T4 levels of block. After the C8 level the block was reinforced to study the effect of a “top-up” dose. Blood samples were drawn from a central venous catheter. Plasma concentrations of norepinephrine and epinephrine were determined by the single isotope radioenzymatic method. Despite extensive block, hemodynamic alterations were minimal, and no significant decrease in plasma epinephrine was observed as the level of analgesia was raised to the C8 dermatome. When the level of analgesia was raised above T8, there was a trend for norepinephrine to decrease, but this decrease did not become statistically significant until analgesia reached the C8 dermatome. Reinforcing the epidural block at the C8 level of analgesia resulted an insignificant decrease in epinephrine and norepinephrine NE. Under the conditions of the present study, epidural block with a sensory analgesia level as high as C8 did not significantly decrease the plasma concentration of epinephrine in unstressed volunteers. The plasma concentration of norepinephrine significantly decreased only when the level of sensory analgesia was approximately C8.

ISSN:0003-3022    

出版商:OVID    

年代:1991

数据来源: OVID