摘要:

A new percutaneous approach to central venous catheterization was recently described which seemed to offer advantages over others commonly used. To evaluate the technique, it was successfully used in 102 consecutive patients for monitoring, drug infusion, pulmonary arterial catheterization, and parenteral nutrition. There was a low incidence of complications, the most frequent being arterial puncture. The results confirm that this is an effective and relatively safe technique that deserves consideration in patients who require central venous catheterization.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Breathing circuit cannisters containing functional CO2absorbent are critical to prevent rebreathing CO2during general anesthesia using closed or semiclosed breathing systems. Ethyl violet is the indicator dye added to Sodasorb® to indicate impending exhaustion of the absorbent. A case of CO2rebreathing due to failure of ethyl violet indicator in exhausted Sodasorb® was encountered. Laboratory investigation demonstrated that dye failure could result from photodeactivation caused by fluorescent lights. Using a fixed intensity fluorescent light source and quantitative spectrophotometric analysis, a highly significant dose-response relationship was demonstrated between duration of light exposure and the decrease in ethyl violet concentration. After 24 h of fluorescent light exposure with a received flux density of 46 nwatts/cm2at 254 nm, the concentration of functional ethyl violet remaining in pulverized Sodasorb® was 16% of the baseline value. Furthermore, using multiple light sources of various intensities, the greater the intensity of light, the more rapid the rate of decline of the ethyl violet concentration. It is recommended to minimize the problem by using ultraviolet filters and incorporating additional ethyl violet in Sodasorb®. Finally, ethyl violet undergoes temporal deactivation after a Sodasorb® container is opened, even if it is stored in the dark.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The effects of maternal isoflurane-oxygen anesthesia (isoflurane, 1% inspired) were measured in eight pregnant ewes and their asphyxiated singleton fetuses. Stable fetal asphyxia, indicated by a stable fetal arterialpH of 7.1–7.2 units, was produced by maternal uterine artery occlusion. Maternal and fetal heart rates and blood pressures; maternal uterine artery flow; maternal arterial, fetal arterial, and sagittal sinuspH; and blood gas tensions were determined during an awake control period, during fetal asphyxia alone, and during fetal asphyxia plus isoflurane-oxygen. Measurements of representative fetal whole organ blood flows, cardiac output, and cerebral oxygen consumption were also made during each of the three experimental periods. During asphyxia alone regional and total brain, heart, and adrenal flows increased above control while flow to the spleen and carcass decreased. Similar responses were seen during asphyxia plus isoflurane-oxygen. Fetal arterial and sagittal sinuspH, base excess, Po2, and oxygen saturation decreased, and hydrogen ion concentrations and Pco2increased during asphyxia alone and asphyxia plus isoflurane-oxygen. Cerebral oxygen consumption decreased significantly from control during asphyxia plus isoflurane-oxygen, whereas no significant changes occurred in cerebral oxygen delivery. These results support the conclusions that in the asphyxiated fetus: 1) acidosis is increased; 2) cardiac output is redistributed to vital organs; and 3) the balance of cerebral oxygen supply-to-demand is maintained during maternal isoflurane-oxygen anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Caffeine and halothane contracture testing is widely used to detect malignant hyperthermia (MH) susceptibility. The accuracy and reliability of the 3% halothane test and the incremental caffeine test, as recommended by the North American MH Group, were assessed in 11 swine (five MHS, six control). Nine swine were tested twice, 4–6 weeks apart. Accuracy of thein vitrodiagnosis was also assessed byin vivoanesthetic challenge. Of all muscle bundles from MH-susceptible swine, 65% reacted positively to 3% halothane and 70% to 2 mM caffeine. Only 35% had a positive caffeine-specific concentration, and 25% developed an increase in baseline tension ≥ 7% at 2 mM caffeine. However, when only the most positive response to 3% halothane or to 2 mM caffeine was used (a minimum of three fresh muscle strips is recommended), these two tests were highly sensitive and specific. In control swine one of 30 muscle bundles reacted positively to 3% halothane. A positive caffeine-specific concentration developed in one of 25 control muscle bundles exposed to caffeine. The variability in the results of these tests mandated that at least three muscle bundles be used for each test. Nonviable muscle bundles sould not be relied upon to provide accurate results. In this porcine model, MH susceptibility could be detected by performing the Caffeine Halothane Contracture Test (CHCT) according to the guidelines of the North American MH Group. However, only the 3% halothane test and the response to 2 mM caffeine produced adequate diagnostic results in this breed of swine.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Pulmonary vascular tone was investigated by the construction of pulmonary arterial pressure (PAP)/cardiac output (&OV0422;) plots, and gas exchange, by the multiple inert gas elimination technique, in 24 anesthetized dogs before and after pulmonary embolization of autologous clots. Three PAP/&OV0422; plots were obtained by a manipulation of venous return at baseline and 60 min and 110 min after embolization. Before the third PAP/&OV0422; plot, the dogs were randomly allocated to one of the following iv treatments: 1) placebo (n = 6); 2) prostaglandin E1(PGE1) 0.4 μg·kg−1·min−1(n = 6); 3) hydralazine 2 mg/kg (n = 6); and 4) nitroprusside 10 μg·kg−1·min−1(n = 6). These vasodilators decreased systemic arterial pressure by a mean of 44%. Ventilation-perfusion (&OV0312;A/&OV0422;) distributions were determined at the same &OV0422; (2.4 ± 0.11·min−1·m−2, mean ± SE) of each PAP/&OV0422; plot. Embolization increased the intercept and the slope of the PAP/&OV0422; plots (p< 0.001). Distributions of &OV0312;A/&OV0422; were only moderately impaired, with an increased dispersion of both &OV0312;Aand &OV0422; and a shift of &OV0312;Adistributions to higher &OV0312;A/&OV0422;. Pao&OV0312;changed from 208 ± 5 to 172 ± 8 mmHg (P< 0.01) (fraction of inspired O20.4). None of the treatments had any effect on &OV0312;A/&OV0422; distributions. Placebo and PGE1had no effect on PAP/&OV0422; plots. Hydralazine and nitroprusside reduced the slope of the PAP/&OV0422; plots. Thus, in this canine model of acute pulmonary embolism: 1) &OV0312;A/&OV0422; distributions were moderately impaired accounting for only slight hypoxemia, and 2) pulmonary hypertension was partially reversible by hydralazine and by nitroprusside without associated non-flow-dependent change in &OV0312;A/&OV0422; distributions and arterial oxygenation.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Using a rat model of incomplete cerebral ischemia the effects of isoflurane (iso) and methohexital (metho) were compared with those of 70% nitrous oxide controls (N2O). Two levels of incomplete cerebral ischemia were produced by right carotid occlusion plus hypotension for 30 min: moderate = 30 mmHg, FIo2= 0.30; severe = 25 mmHg, FIo2= 0.20. The iso doses (1 and 2 MAC) and metho doses (0.01 and 0.1 mg·kg−1·min−1) were tested at each ischemic level. These iso and metho doses were selected because without ischemia they produced similar decreases in cerebral oxygen consumption (CMRo2) compared with that produced in N2O controls. In the absence of ischemia, the electroencephalogram (EEG) was suppressed by 0.01 mg·kg−1·min−1metho and 1 MAC iso and showed burstsuppression with 0.1 mg·kg−1·min−1metho and 2 MAC iso. The EEG was further depressed by ischemia under all anesthetic conditions. Neurologic outcome was evaluated for 3 days following incomplete cerebral ischemia by using a graded deficit score (0 = normal, 5 = death associated with stroke). Following moderate ischemia all four anesthetic treatments improved outcome compared with N2O controls, but after severe ischemia only 2 MAC iso significantly improved outcome. Neurohistopathology was evaluated on a scale of 0 to 40, 24 h after ischemia. The neurohistopathology score was significantly improved by all four anesthetic treatments compared with N2O following moderate ischemia and was better with 2 MAC iso compared with 0.1 mg·kg−1·min−1metho after both moderate and severe ischemia. These results show that both iso and metho improve outcome from cerebral ischemia compared with that associated with N2O, but only 2 MAC iso resulted in an improved outcome following severe ischemia. This difference in outcome between the two anesthetics may be related to greater neuronal depression with iso, which may occur with little difference in cerebral metabolic depression.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Application of the Doppler principle can provide relatively noninvasive and continuous measurement of cardiac output. However, it is based on certain assumptions that may introduce error. Esophageal Doppler cardiac output was compared with Fick cardiac output during acute blood loss (35–45% estimated blood volume) in eight anesthetized pigs. Mean Fick cardiac output decreased from 4.8 to 1.9 1/min, mean Doppler cardiac output from 4.9 to 2.9 1/min. This was accompanied by a decrease in mean arterial pressure from 119 to 55 mmHg and increase in heart rate from a mean of 115 to 156 beats/min. There was an inconsistent association between the two methods both within and between individual animals. Cubic polynomial regression equations of cardiac output with time indicated small measurement error in Fick (R2: mean 0.93, range 0.99–0.75) as opposed to Doppler (R2: mean 0.67, range 0.93–0.16) cardiac output. In one animal Doppler cardiac output showed an increase with time and in one the Doppler cardiac output measurements were unrelated to time. There was highly variable association comparing FickversusDoppler cardiac output with correlations ranging from −0.76 to 0.98. A sign test for mean differences indicated that Doppler derived cardiac output was higher than Fick cardiac output, and the chance of this occurring if the true difference was zero was less than 1 in 1,000. A test for homogeneity of correlations was also rejected. Inaccuracies in individual assumptions in the computation of esophageal Doppler cardiac output, especially unaccounted changes in aortic diameter, are responsible for the inconsistent and unpredictable values of Doppler cardiac output obtained in this experimental model of hemorrhage.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To study the cardiovascular effects of low blood ionized calcium ion concentrations [Ca2+] induced by citrate infusion followed by high [Ca2+], induced by CaCl2infusion awake and during enflurance (2.5% ET), halothane (1.2% ET), and isoflurane (1.6% ET) anesthesia, dogs were chronically instrumented to measure heart rate, aortic, left atrial, and left ventricular (LV) blood pressures, and cardiac output. In conscious dogs low [Ca2+] (decreased 0.35 mM); increased heart rate (HR) and mean aortic pressure (MAP) and decreased stroke volume (SV) and LV dP/dtmax. Low [Ca2+] increased HR during all three anesthetics and decreased LV dP/dtmaxexcept during isoflurane anesthesia. Low [Ca2+] produced more hemodynamic depression during enflurane anesthesia than during anesthesia with halothane or isoflurane increasing left atrial pressure and decreasing MAP and SV. The differences seen were partially related to decreased systemic vascular resistance during halothane and isoflurane anesthesia. In conscious dogs following high [Ca2+] (increased 0.37 mM); only MAP and LV dP/dtmaxincreased. LVdP/dtmaxwas also increased by high [Ca2+] during all three anesthetics without a change in MAP. Cardiac output increased during halothane and isoflurane anesthesia but was unchanged during enflurane. It would appear that the hemodynamic sensitivity for the effects of changing [Ca2+] was enflurane > halothane > isoflurane > awake. The results suggest that the effects of changes in [Ca2+] induced by citrate and CaCl2infusion are modified by the three volatile anesthetics.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The effect of albuterol (aβ2specific adrenergic agonist) on airway reactivity to histamine aerosol challenge was evaluated during halothane anesthesia and thiopental-fentanyi anesthesia in five Basenji Greyhound dogs. Responses to histamine aerosol challenges (0.01, 0.03, 0.1, 0.3, 1.0, and 3.0 mg/ml) were measured during thiopentalfentanyl anesthesia and during halothane anesthesia in the presence and absence of iv albuterol (2.5 μg/kg). Prior to aerosol challenges, baseline pulmonary resistance (RL) and dynamic compliance (Cdyn) did not differ in the four conditions. Albuterol significantly attenuated the pulmonary response to histamine during thiopental-fentanyl anesthesia. Although halothane itself significantly attenuated the pulmonary response to histamine, this response was further attenuated by the addition of albuterol. This study suggests that albuterol is effective in attenuating bronchoconstriction during both thiopental-fentanyl and halothane anesthesia. As the effects of albuterol and halothane on the airways are additive, β-adrenergic agonists such as albuterol are the agents of choice to treat bronchospasm in patients anesthetized with inhalational anesthetics.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The effects of flumazenil, a benzodiazepine antagonist, on the rate of cerebrospinal fluid (CSF) formation (&OV0312;f), resistance to reabsorption of CSF (Ra) and the electroencephalogram (EEG) was determined in 12 dogs anesthetized with halothane (0.4%, end-expired) and nitrous oxide (66%, inspired) in oxygen. In six dogs the responses to flumazenil were measured during administration of midazolam (1.6 mg/kg followed by 1.25 mg &OV0312; kg−1&OV0312; h−1, intravenously) given along with inhalational anesthesia, whereas in the other six dogs the responses to flumazenil were measured during inhalational anesthesia without midazolam. &OV0312;fand Rawere determined using ventriculocisternal perfusion, and EEG activity was evaluated using aperiodic analysis. Flumazenil, 0.0025 and 0.16 mg/kg, was administered both when CSF pressure was normal and when CSF pressure was increased to 36–38 cmH2O by continuous infusion of mock CSF. Flumazenil produced no statistically significant change in &OV0312;f. Flumazenil did produce inconsistent and relatively small changes in Ra. Quantitative aperiodic analysis indicated changes in EEG activity only when the larger dose of flumazenil was given to dogs receiving midazolam. At normal CSF pressure the changes were consistent and were comprised of decreases in &thetas;, α, and total hemispheric power. At elevated CSF pressure the changes were less consistent. It is concluded that smaller doses of flumazenil (which cause no EEG changes with the present method of analysis) and larger doses of flumazenil (which reverse midazolam-induced increase of &thetas; and α activity) produce no change of &OV0312;fand no consistent change of Ra. Although flumazenil given in the presence of midazolam may increase Ra, thereby increasing CSF pressure and impairing contraction of CSF volume, this effect is not likely to be clinically important.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID