摘要:

Polyvinyl chloride (PVC) endotracheal tube segments were exposed to a 5.0-W CO2laser beam in the presence of different fractions of oxygen and either helium or nitrogen. Time from onset of exposure until ignition was recorded, and mean time to ignition (MTI) was calculated after 10 exposures with the same gas mixture. A second series was done with 40% oxygen in either nitrogen or helium and a laser intensity of 7.5, 10.0, or 12.5 W; a third with 40% oxygen, 60% helium, and 2% halothane and a 10.0-W laser beam; and a fourth with 40% oxygen and 60% helium and a 10.0-W laser beam directed at the radioopaque barium sulfate stripe on the tube. With 5.0-W and 20% oxygen in either nitrogen or helium, segments did not ignite. With concentrations of oxygen greater than 20% in nitrogen, segments ignited sooner than with comparable concentrations in helium: MTIHe= 55.6 s and MTIN2= 27.6 s in 40% oxygen (P< 0.05). Sixty per cent helium remained protective at laser intensities up to 10.0 W (MTIHe= 42.6 svs.MTIN2= 14.3 s) (P< 0.05).However, at 12.5 W, MTIHe= 11.5 s and MTIN2= 11.3 s. Two per cent halothane in 40% oxygen and 60% helium reduced MTIHeto 25.3 s compared with 42.3 s without halothane. With the laser directed at the barium stripe, MTIHewas 7.2 s and MTIN21.1 s. Adding helium in concentrations ≥ 60% to anesthetic gases delays laser-induced PVC endotracheal tube fires, if laser intensity is ≤10.0 W and laser bursts are ≤10 s. The barium sulfate stripe should be avoided when using this technique.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Radionuclide cardiography with99mTc-labeled erythrocytes was carried out in three different studies comprising 20 female patients without heart or lung diseases. Left ventricular ejection fraction (LVEF) and other hemodynamic variables were measured immediately before and during induction of anesthesia (thiopental, N2O/O2, succinylcholine, laryngoscopy + oral intubation, halothane). In study 1, serial measurements of LVEF, left ventricular volume, and derived variables were obtained by gamma camera in seven patients using 3-min sampling periods. In Studies 2 and 3, LVEF was monitored serially in seven and six patients, respectively, by a portable, nonimaging probe (nuclear stethoscope) at 1-min intervals or less. The induction period was prolonged to last 24 min in studies 1 and 2, against 9 min in study 3.In studies 1 and 2 there was an increase in blood pressure and heart rate after thiopental and after laryngoscopy and intubation. In study 3 a similar increase was observed after intubation. In the gamma camera study LVEF decreased from 0.72 to 0.53 after thiopental, with no further decrease during intubation. This decrease was accompanied by an increase in end-systolic volume and a decrease in the ratio: systolic cuff pressure/end systolic volume, whereas end-diastolic volume and cardiac index remained unchanged. In the nuclear stethoscope studies, LVEF decreased both after thiopental and after intubation, in study 2 from 0.68 to 0.38 and from 0.53 to 0.41, respectively; in study 3 from 0.69 to 0.53 and from 0.57 to 0.44, respectively.Our observation, in healthy, female individuals, provide an impetus for further noninvasive radionuclide studies during anesthesia in patients with cardiovascular disease.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Avoidance of ketamine has been recommended in children with pulmonary hypertension or with limited right ventricular reserve, despite absence of data about the effects of ketamine on pulmonary vascular resistance (PVR) in children. Ketamine has been associated with increased PVR in studies of adults; in these studies adults were spontaneously breathing through unprotected airways, despite ketamine's known effects of ventilatory depression and partial loss of airway. The authors measured pulmonary and systemic hemodynamic responses to ketamine during spontaneous ventilation in 14 intubated infants who were receiving minimal ventilatory support with an intermittent mandatory ventilation (IMV) of 4 at an FIO2of 0.3–0.4. No significant changes were found in cardiac index (CI), pulmonary vascular resistance index (PVRI), or systemic vascular resistance index (SVRI) in a group of seven infants with normal PVRI or in another group of seven infants with preexisting increased PVRI. Results did not differ in infants receiving diazepam sedation. The authors conclude that ketamine has little effect on baseline hemodynamics in mildly sedated infants whose airway and ventilation are maintained; in particular, PVRI is little changed by ketamine administration in ventilated infants with either normal or increased baseline PVRI.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Mean arterial pressure, heart rate, plasma catecholamines, renin activity, and vasopressin changes induced by a 30-degree head-up tilt were studied before and during epidural anesthesia with bupivacaine in eight elderly patients (ages 58–82 yr). The tilt performed before epidural anesthesia did not modify mean arterial pressure, heart rate, plasma catecholamines, renin activity, and vasopressin at 5 and 15 min. During epidural anesthesia, the superior level of analgesia ranged from T4 to T10. Epidural anesthesia induced significant (P< 0.05) decreases from control values in mean arterial pressure and plasma norepinephrine (from 85 · 6 to 67 · 8 mmHg and from 600 · 108 to 307 · 77 pg/ml, respectively, mean ± SEM) without significant changes in heart rate, plasma epinephrine, renin activity, and vasopressin. However 5 and 15 min after tilt, significant decreases from pretilt values were measured in mean arterial pressure (from 67 · 8 to 57 · 6 and 55 · 6 mmHg, respectively) and in heart rate (from 70 · 8 to 63 · 7 and 62 · 7 beats/min). Simultaneously, an increase in plasma vasopressin (from 14.8 · 5.5 to 36.2 · 10.3 and 40.0 · 10.5 pg/ml) was recorded, whereas plasma norepinephrine and epinephrine remained unchanged. Posttilt plasma renin activity values at 5 and 15 min were increased significantly when compared with the preepidural values (2,752 · 1,168, 2,410 · 1,214 and 713 · 190 pg · ml−1· h−1, respectively). The authors conclude that during epidural anesthesia in elderly patients 1) the heart rate and the plasma catecholamines responses to hypotension induced by tilt are impaired, even if the level of analgesia is below T4; and 2) vasopressin and, to a lesser degree, the renin–angiotensin system may play important roles in the regulation of arterial pressure.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Pulmonary gas exchange during conventional mechanical ventilation (CMV) (tidal volume 10 ml/kg, rate 8–10 breaths/min) was compared with that during high-frequency small-volume ventilation (HFV) in 67 patients undergoing anesthesia for various surgical procedures. HFV was studied at oscillation frequencies ranging from 3 to 18 Hz with stroke volumes of 0.8 to 2.2 ml/kg. Adequate pulmonary gas exchange was achieved with CMV and HFV, and the efficiency of oxygenation, that is, (A-a)DO2, was similar in the two conditions. During HFV, the lung volume was higher than during CMV in most patients. Muscle paralysis did not significantly change either PaCO2, or PaO2. In general, increasing fresh gas flow into the HFV system above approximately 10 1/min resulted in little reduction in PaCO2, but reduction of fresh gas flow below approximately 6 1/min increased PaCO2progressively. Currently, we do not recommend HFV at 12–18 Hz for routine use during anesthesia for orthopedic or abdominal surgery.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The mutagenic effects of several inhaled anesthetic agents were investigated using the sex-linked recessive lethal assay in the fruit fly,Drosophila melanogaster. Male wild-type flies were exposed for 1 hr to either halothane, enflurane, isoflurane, or fluroxene at vapor concentrations of 1 or 2% or to nitrous oxide at concentrations of 40 or 80%. Control flies were exposed to air alone. Following treatment, male flies were mated with untreated virgin females of theBascstrain and the rate of sex-linked recessive lethals was determined in the F2generation. Halothane and fluroxene produced a dose-dependent and statistically significant increase in the rate of sex-linked recessive lethals, whereas enflurane, isoflurane, and nitrous oxide were not mutagenic at the concentrations tested.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

In an attempt to evaluate health experiences of operating room personnel using previously published reports, the authors calculated summary relative risks (RRs) for each outcome under investigation by combining data from six studies. For each summary RR, they also calculated 95% confidence limits; when the range of the confidence interval excludes 1.0, the increased risk is statistically significant at the 0.05 level. The most consistent evidence was for spontaneous abortion among pregnant physicians and nurses who work in operating rooms, where the RR was 1.3 (95% confidence limits from 1.2 to 1.4). For liver disease there were statistically significant increased RRs among both men (1.6, 1.3–1.9) and women (1.5, 1.2–1.9), but these were based on smaller numbers of studies. Although the results of pooled analyses are suggestive, most studies of this issue have relied on voluntary responses and self-reported outcomes, so that response and/or recall bias could explain these findings. In addition, these investigations generally have examined working in operating rooms rather than actual exposure to anesthetic gases. Finally, there have been considerable improvements in operating room scavenging systems during the last decade. Thus, prospective cohort studies are needed to determine whether there is a relationship between current levels of occupational exposure to anesthetic gases and adverse outcomes, particularly spontaneous abortion and liver disease.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

MAC determinations for halothane, enflurane, and isoflurane were performed in New Zealand white rabbits (n = 8, approximate age 6 months). The MAC values (±SD) were as follows: halothane 1.39 · 0.23%, enflurane 2.86 · 0.18%, and isoflurane 2.05 · 0.18%. Comparison of these results with published MAC values for other species suggests that the ratio of the potencies for any pairing of these three agents is constant from species to species. This observation provides a means for assessing the validity of preexisting or newly determined MAC values.

ISSN:0003-3022    

出版商:OVID    

年代:1985

数据来源: OVID