ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Five groups of surgical patients, each comprising six individuals, received epidural doses of morphine or meperidine, and the plasma and CSF kinetics were studied. Three groups received epidural doses of morphine 3 mg in 1 or 10 ml or meperidine 30 mg in 1 ml. Cerebrospinal fluid (CSF) and central venous blood opioid concentrations were measured intermittently for 6 h after injection. Two groups received epidural doses of morphine 3 mg in 1 ml or meperidine 30 mg in 1 ml, and opioid CSF concentrations were determined over a 24-h period. Morphine appeared rapidly in plasma, and maximum plasma concentrations were usually detected 5 min after injection and averaged 33 ng · ml-1in the 1-ml volume group and 40 ng · ml-1in the 10-ml volume group. The terminal plasma half-life averaged 91 ± 34 min and 87 ± 27 min, respectively (mean ± SEM). Maximal plasma concentrations of meperidine were usually detected 10 or 15 min post-injection and averaged 196 ± 29 ng · ml-1. The terminal plasma half-life averaged 124 ± 26 min. Morphine crossed the dura relatively slowly, and the absorption half-life across the dura averaged 22 min. Maximal CSF concentrations were usually seen 60–90 min post-injection. In contrast, me peridine crossed the dura quickly, with an absorption half-life averaging 7.6 ± 2.0 min. Maximal CSF concentrations were seen 15 or 30 mid post-injection. Morphine and meperidine concentrations remained several times higher in the CSF than in the plasma. The fraction of the opioid dose crossing the dura was calculated to be 3.6% for morphine and 3.7% for meperidine. There were no significant differences in the kinetics of morphine administered in 1 or in 10 ml when CSF was sampled close to the site of lumbar epidural injection. The CSF concentration-time curves of both drugs decreased biexponentially after the initial rise due to diffusion across the dura. The early half-life in CSF averaged 73.3 ± 11.5 min for morphine and 71.3 ± 3.1 min for meperidine, and the late half-life averaged 369 ± 113 min for morphine and 982 ± 449 min for meperidine. Dose-normalized morphine and meperidine CSF concentrations after epidural administration showed that meperidine concentrations were down to one-fourth the corresponding morphine concentrations from the 2nd to the 15th h after administration, which may partly explain the longer duration of analgesia from morphine. Compartment analysis showed that meperidine is removed faster than morphine from the CSF after epidural adminstration, which may reduce the risk of cephalad transport and supraspinal adverse effects.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Two groups of surgical patients each comprising six individuals received an intrathecal injection of morphine 0.3 mg or meperidine 10 mg. Cerebrospinal fluid (CSF) and plasma were sampled frequently during a 6-h period and analyzed for morphine or meperidine. Maximum plasma morphine concentrations were found 5–10 min after injection, and averaged 4.5 ± 1.1 ng · ml-1(mean ± SEM). Maximum CSF morphine concentrations were considerably higher than maximum plasma concentrations, 6410 ± 1290 ng · ml-1. Maximum plasma concentrations of meperidine were also measured 5 or 10 min after injection and were low (36 ± 9 ng · ml-1) compared with the maximum CSF concentrations (364 ± 105 μg · ml-1). After a rapid initial decline for about 15 min after injection, the CSF concentrations decreased with a half-life of 89.8 ± 16.1 min for morphine and 68.0 ± 5.1 min for meperidine during the rest of the study period. The initial volume of distribution in CSF was similar for both drugs, or 22 ± 8 ml for morphine and 18 ± 5 ml for meperidine. After 6 h, 1.6 ± 0.9% of the injected morphine dose and 0.41 ± 0.09% of the meperidine dose remained in the initial volume of distribution. Large inter-individual differences in morphine and meperidine CSF kinetics existed, which may explain some of the reported individual differences in duration of effects. The disappearance of meperidine from CSF tended to be faster than that of morphine, which may be explained, in part, by the differences in lipid solubilities of the drugs.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The profile and duration of action of triethyldodecyl ammonium bromide (TEA-C12) on natural spike activity of rabbit aortic nerve was examined. To study the profile of action, a segment of the aortic nerve of anesthetized rabbits was placed in a perfusion chamber and exposed to increasing concentrations of TEA-C12and, for comparison, of procaine. Total nerve activity was recorded continuously and its change related to drug concentrations (concentration/effect curves). The half-lives of onset time after drug administration and recovery following drug-washout were also determined. To study the duration of conduction block induced by TEA-C12, the aortic nerve of anesthetized rabbits was exposed to a concentration slightly higher than the minimal blocking concentration for an average time of 130 min after complete conduction block occurred. Three to 40 days later, the nerves were examined both neurophysiologically and neuropathologically. TEA-C12blocked nerve activity in a concentration-related manner, as did procaine, however, the onset time (t1/5) was much slower for TEA-C12(9.2 min) than for procaine (2.2 min). Most importantly, TEA-C12block could not be reversed within 9 h of drug-washout, whereas all the procaine-blocked nerves completely recovered (t1/2= 3.0 min). Nerve activity was completely blocked by TEA-C12and nerve block was accompanied by severe morphological damage with complete loss of myclinated nerve fibers and severe axonal edema of the remaining axons for about 4 weeks. Nerve function completely recovered, but with only partial morphological restoration between day 30 and 40 after the initial block. Thus, TEA-C12blocked natural spike activity of the aortic nerves of rabbits in a concentration-related manner, but this block was maintained for about 4 weeks by neurotoxic damage.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The influence of halothane, pentobarbital, and their interaction on the passage of air across the pulmonary circulation was studied in 12 dogs using transesophageal M-mode echocardiography for air detection in the left atrium and/or aorta. Air was detected in the left atrium and/or aorta after pulmonary artery air injection of 0.04 ml/kg during 1% halothane anesthesia (n = 5). Addition of pentobarbital changed the threshold to 1.0 ml/kg. During pentobarbital anesthesia with and without halothane (n = 7), the thresholds were 1.1 and 1.2 ml/kg, respectively. The authors conclude that the threshold for transpulmonary passage of venous air is higher during anesthesia with pentobarbital with or without halothane than during anesthesia with halothane alone.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Controversy exists as to whether the halogenated inhalation (IH) anesthetics impair arterial oxygenation during one-lung ventilation (1-LV). Accordingly, the authors have answered this question in 12 consenting patients who required 1-LV to facilitate the performance of thoracic surgery, by comparing arterial oxygenation during a prolonged period of IH anesthesia with arterial oxygenation during a prolonged period of intravenous (IV) anesthesia during stable 1-LV conditions. The patients were equally divided into halothane and isoflurane groups. Each patient in each III anesthetic group underwent the following experimental sequence: step 1, two-lung ventilation (2-LV), 1 MAC IH anesthesia; step 2, 1-LV, 1 MAC IH anesthesia; step, 3, 1-LV, iv anesthesia; step 4, 2-LV, iv anesthesia. Stable 1-LV conditions were proven by serial arterial blood gas measurement. Conversion from 2-LV to 1-LV during III anesthesia (step 1 to step 2) caused a very large and significant decrease in Pao1(from 484 ± 49 to 116 ± 61, and from 442 ± 58 to 232 ± 97 mm Hg in the halothane and isoflurane groups, respectively) and increase in shunt (from 14 ± 4 to 44 ± 9, and from 19 ± 5 to 31 ± 8% in the halothane and isoflurane groups, respectively). Conversion from 1 MAC halothane anesthesia to iv anesthesia during 1-LV caused a slight but significant decrease in shunt (2 ± 2% of the cardiac output) and increase in Pao1(39 ± 29 mmHg), whereas conversion from 1 MAC isoflurane anesthesia to iv anesthesia caused a very slight and nonsignificant decrease in shunt (2 ± 2% of the cardiac output) and increase in Pao1(13 ± 19 mmHg). Return to 2-LV (step 3 to step 4) cansed a large and significant increase in Pao1(from 155 ± 84 to 411 ± 101 mmHg, and from 245 ± 97 to 431 ± 104 mmHg in the halothane and isoflurane groups, respectively) and a large decrease in shunt (from 37 ± 9 to 20 ± 8, and from 36 ± 5 to 20 ± 7% in the halothane and isoflurane groups, respectively). The authors calculated that the atelectatic lung had hypoxic pulmonary vasoconstriction (HPV) and that the slight increase in shunt and decrease in Pao1caused by changing from IH to iv anesthesia was consistent with the finding in animal studies that 1 MAC IH anesthesia causes a 20% inhibition of HPV. In view of the usual efficacy of nondependent lung CPAP1the authors conclude that IH anesthetic drugs are safe to use in patients undergoing 1-LV.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

To investigate the extent to which reduced pulmonary flow may affect non-ventilalory functions of the lung, pulmonary artery pressures were altered systematically in anin vitroperfused lung preparation. Metabolic integrity of the tissue was assessed at two levels: disposition of exogenous serotonin (5-hydroxytryptamine; 5-HT) was monitored as a specific indicator of endothelial cell metabolism; and whole-tissue rates of protein synthesis and levels of ATP were evaluated as indices of general metabolic activity and energy availability. Rat lungs were perfused with recirculating cell-free buffer (37°C) for I or 3 h at high (36) or low (3 ml · min-1· g-1) pulmonary flow; initial rates of 5-HT metabolism were measured over a subsequent 2-min interval of single-pass perfusion. Metabolism of 5-HT was inhibited and protein synthesis decreased 35% at low pulmonary flow. These changes did not appear to result directly from hypoxia, nor from the associated fall in tissue ATP. The effects of low flow were not reversed at high Po1, nor was 5-HT metabolism inhibited by restricted oxygen availability at high How rates. After as long as 3 h exposure to a combination of low flow, ventilation (&OV0312; = 0), and temperature (27° C) and to the volatile anesthetic, halothane, inhibitory effects on both amine and protein metabolism were rapidly reversible. Reductions in the rate of 5-HT metabolism at reduced flow involved a decrease in the maximal velocity (Vmax: 8.0 to 2.2 nmol · min-1· g-1), without change in the apparent Km (2.6–3.2 μM) of the pathway for amine metabolism. These changes in endothelial metabolism thus appear to reflect a low flow-associated reduction in vascular surface area, rather than general metabolic alterations due to hypoxiaper se.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Although nitrous oxide is commonly administered to patients with ischemic heart disease, recent reports suggest that it may induce myocardial ischemia in these patients. The authors compared the effects of nitrous oxide on segmental left ventricular (LV) function and the ST segment of the electrocardiogram with the effects of an equal concentration of nitrogen (crossover design) before the start of surgery in 18 patients who required coronary-artery bypass grafting. The patients studied did not have valvular or LV dysfunction. Anesthesia was induced and maintained with intravenous fentanyl. After endotracheal intubation and 20 min of ventilation with 100% oxygen, either 60% nitrous oxide or 60% nitrogen (randomly assigned) was added to the inspired gas mixture of each patient for 10 min. This was followed by 10 min of 100% oxygen, and then 10 min of 60% nitrous oxide or 60% nitrogen, whichever had not been administered previously. Patients were monitored for myocardial ischemia using a standard 12-lead electrocardiogram and transesophageal two-dimensional echocardiography. Surgery did not begin until the study was concluded. No patient experienced an ST segment change > 1 mm during the study, and none developed a new segmental wall motion abnormality during inhalation of either nitrous oxide or nitrogen. The authors conclude that nitrous oxide does not induce myocardial ischemia when used as an adjunct to fentanyl anesthesia in patients who have severe coronary-artery disease accompanied by well-preserved valvular and LV function.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

A prospective cohort study of 489 pediatric patients was performed to investigate the prevalence of perioperative respiratory complications and symptomology in children presenting for myringotomy with upper respiratory tract infections (UR1s). All children undergoing myringotomy received halothane N2O/O2anesthesia administeredviaface mask. Information on complications and respiratory symptoms was obtained from the anesthesia and recovery room records, and by standardized questionnaire. There were no significant differences in perioperative complications between asymptomatic children (1.23%), symptomatic children fulfilling predetermined URI criteria (1.28%), and symptomatic children that did not fulfill the URI criteria (2.38%). In addition, the prevalence and duration of respiratory symptoms was significantly less in children having received anesthesia and surgery than in a matched group of non-anesthetized controls who did not have surgery. Results from this study suggest that there is no increased morbidity for children presenting at minor surgery with acute uncomplicated URIs and who did not require tracheal intubation. In addition, the administration of general anesthesia and surgery to this group of patients was followed by a decrease in both the appearance and duration of a number of respiratory symptoms.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Although it is generally accepted that a decrease in plasma oncotic pressure may result in the formation of peripheral edema, the effect of a hypo-oncotic state on brain water content is less well known. Therefore, utilizing the technique of hollow-fiber plasma-pheresis to manipulate plasma composition, the authors examined the effects of acute changes in either plasma osmolality or colloid oncotic pressure on the EEG, regional cerebral blood flow, intracranial pressure, and brain tissue specific gravity (as a measure of cerebral water content) in anesthetized, neurologically normal New Zealand white rabbits. Animals in which either osmolality or oncotic pressure was decreased by plasma replacement with an appropriate solution were compared with a group of control animals in which both of these variables were maintained constant. Animals in which plasma osmolality was decreased by 13 ± 6 mOsm/kg (from a baseline value of 295 ± 5 mOsm/kg) showed evidence of a significant increase in cortical water content (≈0.5%), whereas a 65% reduction in oncotic pressure (from 20 ± 2 mmHg to 7 ± 1 mmHg) failed to produce any change. There were no significant differences in mean arterial pressure, central venous pressure, regional cerebral blood flow, or the EEG between any of the groups. Although intracranial pressure increased in all groups, the largest increase (8.1 ± 4.4 mmHg) occurred in those animals whose osmolality was reduced. The increase in intracranial pressure in animals rendered hypo-oncotic was no different front the “control‘’ group (2.4 ± 0.9 mmHgvs. 3.0 ± 1.5 mmHg). This study suggests that an acute fall in oncotic pressure does not promote an increase in cerebral water content in the non-injured brain. Unlike peripheral tissues, the presence of the blood-brain barrier with its small pore size and limited permeability may serve to enhance the importance of osmolality and minimize the role of oncotic pressure in determining water movement between the vasculature and brain tissue.

ISSN:0003-3022    

出版商:OVID    

年代:1987

数据来源: OVID