摘要:

Cardiovascular function, serum ionized calcium (Ca+2), and serum citrate were measured intraoperatively in patients (n = 9) undergoing orthotopic hepatic homotransplantation. Serum citrate increased 20-fold (P< 0.0006) following transfusion of citrated blood products in the absence of a functional liver. Serum ionized calcium decreased (P< 0.003) with concomitant decreases in cardiac index (P< 0.005), stroke index (P< 0.004), and left ventricular stroke work index (P< 0.001). Hemodynamic depression and ionic hypocalcemia were reversed following the administration of CaCl2. In contrast to patients with normal hepatic function, who may tolerate large amounts of citrated blood, patients with end-stage liver disease demonstrate acute ionic hypocalcemia with concomitant hemodynamic depression when receiving citrated blood products during the course of hepatic transplantation.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Halothane is commonly viewed as a more potent cerebral vasodilator than isoflurane. It was speculated that the lesser vasodilation caused by isoflurane might be the result of the greater reduction in cerebral metabolic rate (CMR) that it causes, and that the relative vasodilating potencies of halothane and isoflurane would be similar if the two agents were administered in a situation that precluded volatile-agent-induced depression of CMR. To test this hypothesis, cerebral blood flow (CBF) and the cerebral metabolic rate for oxygen (CMR01) were measured in two groups of rabbits before and after the administration of 0.75 MAC halothane or isoflurane. One group received a background anesthetic of morphine and N2O, which resulted in an initial CMR01of 3.21 ± 0.17 (SEM) ml · 100 g−1· min−1; second group received a background anesthetic of high-dose pentobarbital, which resulted in an initial CMR01of 1.76 ± 0.16 ml · 100 g−1· min−1. In rabbits receiving a background of morphine sulfate/ N2O, halothane resulted in a significantly greater CBF (65 ± 10 ml · 100 g−1· min−1) than did isoflurane (40 ± 5 ml · 100 g−1· min−1). Both agents caused a reduction in CMRO1, but CMRO1was significantly less during isoflurane administration. By contrast, with a background of pentobarbital anesthesia, CBF increased by significant and similar amounts with both halothane and isoflurane. With halothane, CBF increased from 22 ± 2 ml · 100 g−1· min−1in the control state to 39 ± 3, and with isoflurane from 24 ± 2 to 38 ± 2 ml · 100 g−1· min−1. CMR01was not depressed further by either halothane or isoflurane. These results suggest that the relative effects of halothane and isoflurane on CBF are dependent on the CMR present prior to their administration. When the preexistent CMR is not markedly depressed, isoflurane decreases CMR and causes less cerebral vasodilation than does halothane. When initial CMR is depressed, halothane and isoflurane have similar vasodilating potencies.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Recent reports of opiate receptors in the peripheral nervous system have led to the hypothesis that the analgesic action of opiates might, in part, result from a reduction in response of peripheral nerve fibers thought to be concerned with signaling pain (nociceptive afferents). The authors examined the effects of the narcotics, fentanyl (up to 30 μg/kg, iv) and morphine (1 mg/kg, iv), on the response of single unmyelinated afferents (C-fiber nociceptors and warm fibers), recorded a monkeys, to heat stimuli applied to their receptive fields. Neither narcotic affected the response of the afferents. In addition, naloxonc did not affect their response. Thus, an alteration of cutaneous nociceptor response is unlikely to contribute to the analgesic action of narcotics.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Recently, an inhibitory dopaminergic receptor has been described that modulates catecholamine release from adrenal medulla. It has also been reported that low doses of droperidol increase arterial pressure in some patients with pheochromocytoma. The authors investigated whether an effect of droperidol on such a receptor could be one of the mechanisms involved in the hypertensive response. Isolated cat adrenal glands were perfused with Krebs-bicarbonate solution, and the catecholamine release was measured in the effluent. Then, the glands were stimulated by activation of the nicotinic receptor (nicotine, 5μM), and the effect of low and high doses of droperidol and/or apomorphine on the catecholamine secretory responses evoked by nicotine was investigated. Low concentrations of droperidol (0.05 μM) (a dopaminergic antagonist) markedly increased the secretory response induced by nicotine whereas higher concentrations (50 μM) decreased it. Apomorphine (1 μM) (a dopaminergic agonist) inhibits the catecholamine release produced by nicotine, and this inhibitory effect was completely reversed by the lowest concentration of droperidol but not by the highest. In fact, the high concentration of droperidol further inhibited the catecholamine release induced by nicotine. The results suggest that the hypertensive responses evoked by low doses of droperidol in some patients with pheochromocytoma could be due to the inactivation of a dopaminergic inhibitory system present in the adrenal medulla that, under physiologic conditions, limits the amount of catecholamines released by the gland. Such as an inhibitory mechanism could operate in an exaggerated manner in patients with pheochromocytoma.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

This study explored the prejunctional actions of vecuronium using thein vivocat soleus nerve-muscle preparation. Vecuronium doses of 1 to 5 μg/kg iv suppressed the repetitive firing of the motor nerve endings, and the obligatory potentiation of the twitch response following high-frequency conditioning at 400 Hz for 10 s without attenuating neuromuscular transmission at 0.4 Hz. It was also found that extremely low doses of vecuronium had excitatory effects at the cat soleus motor nerve endings: doses of 0.5 and 1 μg/kg is evoked a modest postdrug repetitive firing of the nerve endings and a concomitant potentiation of the muscle responses. These dose-related agonist and antagonist activities suggest that at the motor nerve endings, vecuronium is a weak partial agonist. The major action of vecuronium at the motor nerve endings, however, was suppressive, and this antagonist action contributed to the neuromuscular blocking action of this muscle relaxant.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Nineteen critically ill patients with acute respiratory failure were studied to compare the hemodynamic effects of continuous positive-pressure ventilation (CPPV) and high-frequency jet ventilation (HFJV) at comparable levels of alveolar ventilation. Patients were divided into three groups: Group 1 included seven patients without circulatory shock in whom mean airway pressure (Paw) was slightly higher during CPPV than during HFJV (17.3 ± 3.0vs.13.0 ± 2.9 mm Hg); Group 2 included six patìents without circulatory shock in whom HFJV and CPPV were compared at the same level of Paw (19.2 ± 5.0 mm Hg); Group 3 included seven patients with circulatory shock in whom HFJV and CPPV were compared at the same level of Paw (16.0 ± 3.9 mm Hg). The following respiratory frequencies were used in HFJV: Group 1, 200 ± beats/min; Group 2, 238 ± 103 beats/min; Group 3, 286 ± 149 beats/min. In all patients comparable levels of Paco2were obtained with CPPV and HFJV. In Group 1 patients, mean arterial pressure, cardiac index, and stroke index were significantly higher during HFJV. In Group 2 patients, no significant difference was found between HFJV and CPPV. In Group 3 patients, the following hemodynamic variables were significantly higher during HFJV: mean arterial pressure (71 ± 24vs.84 ± 23 mm Hg), cardiac index (3.6 ± 1vs.4.1 ± 1.41 · min−1· m−2), and oxygen delivery (403 ± 93vs.471 ± 124 ml · m−1· m−2). However, Pao2was significantly lower (210 ± 105vs.155 ± 99 mm Hg, fractional inspired oxygen content [FIo2] 1) and pulmonary shunt (Qs/Qt) was significantly higher (31 ± 12vs.36 ± 11%) during HFJV. These results demonstrate that patients with circulatory shock and acute respiratory failure have a more favorable hemodynamic profile during HFJV than during CPPV at identical levels of Paw.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effects of anesthetic doses of ketamine (iv bolus of 3 mg · kg−1followed by a continuous infusion of 20 μg · kg−1· min−1) on functional residual capacity (FRC) measured by the helium dilution method and on the breathing pattern recorded by a noninvasive method (NIM) based on chest wall circumference changes were studied in 14 ASA P.S.I patients. Ketamine anesthesia was associated with: 1) the maintenance of FRC, minute ventilation, and tidal volume; 2) an increase in rib cage contribution to tidal breathing; and 3) an alteration of volume-motion relationships of the chest wall compartments. It is concluded that: 1) in contrast to volatile anesthetic agents, ketamine anesthesia has a sparing effect on intercostal muscle activity, which may explain the maintenance of FRC; and 2) changes in chest wall geometry and compliance induced by anesthetic agents must be taken into account for NIM to be valid.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The cerebrovascular and cerebral metabolic chancges produced by intraperitoneal injection of phenobarbital (50, 150, and 250 mg/kg) were studied in young adult (6-month) and senescent (28-month) Wistar rats. Cerebral blood flow (CBF) was measured using radioactive microspheres and cerebral oxygen consumption (CMRO2) was obtained by multiplying cortex CBF by the arterial-sagittal sinus oxygen content difference. Control values for blood pressure, blood gas tensions, CBF, and CMRo2were similar in the young and aged animals during 70% N2O/30% O2. Intraperitoneal phenobarbital produced dose-dependent decreases in CBF with no significant difference between young and aged rats at each phenobarbital dose. At the highest phenobarbital dose (250 mg/kg) CBF was reduced by 49% in the young rats and 52% in the aged rats (P> 0.10). CMRo2was also depressed in a dose-dependent fashion in both young and aged animals with each phenobarbital dose. However, the decrease produced by the highest phenobarbital dose was significantly greater in the aged rats (55%) than the young rats (43%,P< 0.05), even though the EEG was isoelectric in both groups. The difference in CMRo2between youngversusaged rats at a time when the EEG is isoelectric suggests that high-dose phenobarbital may depress nonelectrical cerebral metabolic processes more in aged rats.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effects of lidocaine or verapamil on pancuronium neuromuscular blockade and the ability of anticholinesterase agents to antagonize these combined blockades were studied in 14 cats using a standard peroneal nerve-anterior tibialis muscle preparation. Pancuronium was infused at a constant rate to produce a stable 50% depression of single twitch tension. In nine cats, intravenous lidocaine boluses followed by a constant infusion produced serum lidocaine levels of 5.09± 1.9 μg/ml (mean ± SD) and resulted in an additional 20.0 ± 5.5% depression of twitch tension. In the other five cats, intravenous injection of 0.15 mg/kg of verapamil produced an additional 12.8 ± 8.0% twitch depression of pancuronium-induced neuromuscular blockade. For individual animals, edrophonium antagonism of the combined lidocaine-pancuronium-induced neuromuscular blockade or combined verapamil-pancuronium-induced neuromuscular blockade was not significantly different from antagonism of an equivalent twitch depression produced by pancuronium alone. It is concluded that lidocaine and verapamil augment neuromuscular blockade caused by pancuronium and that anticholin-esterase antagonism of this augmented blockade can be expected to occur in a normal fashion.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effects of the neodymium-yttrium aluminum garnet (Nd-YAG) laser on several commonly used endotracheal tubes were examined. Six different types of tubes were tested for flammability. Three tubes were clear, transparent polyvinylchloride with black lettering on the surface. One was yellow–green silicone rubber with green lettering on the surface. One, which was opaque gray with no printing or marks on it, was designed specifically for use with the carbon dioxide (CO2) laser, and one was opaque red rubber with black letters printed on the surface. The latter was tested with and without a wrapping of reflective aluminum tape. On each tube a clear, unmarked area and an area with printing were tested. In each area the tube was impacted by the laser at three to five points. Pulsed and continuous patterns of laser impact were used. Power ranged from 20 to 50 W. The clear polyvinylchloride tubes were not damaged by a pulsed pattern of exposure in unmarked areas. Segments with black printing or marks were consistently damaged. Continuous laser exposure consistently damaged clear portions of the tube. In clear unmarked areas, silicone rubber tubes were damaged with the pulsed pattern when exposure reached 50 W for I s. Areas with green lettering were damaged at the lowest level of exposure. Continuous laser exposure at 30 W damaged clear portions of these tubes after 7 s. Opaque red rubber and opaque gray tubes were damaged at the lowest levels of exposure in both clear and marked areas with pulsed and continuous laser emission. A wrapping of reflective aluminum tape offered no protection. The study demonstrated that all the tubes tested are vulnerable to damage when exposed to the Nd-YAG laser. Transparent, unmarked polyvinylchloride is relatively resistant. Colored markings on clear tubes and colored opaque or semiopaque tubes absorb the light energy and are easily damaged. In contrast to CO2laser exposure the covering of red rubber tubes with reflective aluminum tape offers no protection.

ISSN:0003-3022    

出版商:OVID    

年代:1986

数据来源: OVID