ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A retrospective analysis of the influence of respiration was carried out in three patients with artificial hearts. During spontaneous ventilation, large swings in intrathoracic pressure can produce a pattern reminiscent of pulsus paradoxus in the systemic arterial pressure. A decrease in intrathoracic pressure decreased biventricular filling and enhanced biventricular emptying. An increase in intrathoracic pressure increased biventricular filling, but acting as an increased afterload, impeded biventricular emptying. The influence of respiration on the artificial heart can be considered the result of the artificial ventricles' functioning effectively as extrathoracic pumps, such that changes in intrathoracic pressure produce gradients for biventricular filling and ejection relative to atmospheric pressure (which serves as the reference pressure for the artificial ventricles). Respiratory-induced variation in ventricular performance is clearly present with the artificial heart, but the mechanisms producing these changes appear to be markedly different from normal conditions, in which the ventricles are functionally within the thorax and have a compliant common septum allowing ventricular interaction.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The authors performed a clinical trial in 313 patients in labor to determine the safety and efficacy of an air test for unintentional intravenous placement of epidural catheters. Following routine aspiration for blood and cerebrospinal fluid, 1 ml of air was injected through each epidural catheter while heart tones were continually monitored with a Doppler ultrasound probe placed over the maternal precordium. In 281 patients, Doppler heart tones did not change following air injection (negative air test). All but eight of these patients developed an adequate level of analgesia following anesthetic administration, and no patients with negative air tests developed signs or symptoms of local anesthetic toxicity (false-negative rate, 0%; 95% confidence limits, 0.0–1.1%). Doppler heart tone changes followed air injection in 22 cases (positive air test). In 16 of these, intravenous catheter position was subsequently shown by aspiration of blood from the catheter or by the use of test doses consisting of local anesthetics with or without epinephrine. In six cases, adequate levels of analgesia developed despite a positive air test (false-positive rate, 2%; 95% confidence limit, 0.7–4.3%). None of the 303 patients receiving the air test developed any complications attributable to the injection of air (95% confidence limits, 0.0–1.0%). The authors conclude that air, with precordial Doppler detection, is a safe and effective test for identifying intravenously located epidural catheters.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The authors used closed-loop feedback control of infusion of atracurium to study the effect of prior administration of succinyl-choline on neuromuscular blockade induced by atracurium in patients undergoing otolaryngologic surgery. Anesthesia was maintained with nitrous oxide in oxygen, flunitrazepam, and fentanyl. Of 14 patients given atracurium, seven were given prior administration of succinylcholine and seven were not. Interaction between the two drugs was quantified by determining the asymptotic steady-state rate of infusion necessary to produce a constant 90% neuro-muscular blockade. This was accomplished by applying nonlinear curve-fitting to data on the cumulative dose requirement during anesthesia. The neuromuscular blocking effect of atracurium was found to be greater after prior administration of succinylcholine. The asymptotic steady-state rate of infusion (±SD) for atracurium was 0.27 ± 0.06 mg·kg-1·h-1for patients given succinylcholine and 0.38±0.10 mg·kg-1·h-1for those not given succinylcholine. The clinical implication of this study is that the clinician should be aware of the fact that an induction dose of 1 mg/kg of succinylcholine does reduce atracurium requirement for 90% neuromuscular blockade by approximately 30%.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

We recorded the frequency with which anesthesia personnel came in contact with patient body fluids in order to provide an empirical basis for the recommendation of relevant precautions. Anesthesia personnel completed a questionnaire when performing a range of standardized procedures. The rate of contact with blood was as follows: catheterization of peripheral vein, 18%; insertion of central venous catheter, 87%; arterial puncture, 38%; lumbar puncture, 23%; catheterization of the extradural space, 34%; tracheal intubation, 4%; tracheal extubation, 9%; suction of oral cavity, pharynx, or trachea, 13%; intramuscular injection of drug, 8%; and establishment or discontinuation of drip for blood transfusion, 43%. By using protective gloves, 98% of contacts with patient blood would have been prevented. Blood contact was more frequent in the emergency ward than in the operating room (P< 0.05). Health care workers were not able to predict when a specific procedure would imply that contact with patient blood would occur. We recommend that specific precautions be adopted for the various procedures and discuss precautions that could have prevented contact with body fluid.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

We performed a prospective randomized controlled trial to assess the efficacy of a chlorhexidine dressing in reducing the microbial flora at the insertion site of epidural catheters. These catheters were used for acute pain management and were dressed either by a standardized method or with a CHX/urethane sponge composite. Microbial colonization of the catheter developed in 9 of 31 controls (29.0%) and 1 of 26 (3.8%) catheters with the CHX dressing (P< 0.05). The CHX dressing caused no adverse effects. The data suggest that delivery of antiseptic to the catheter wound site reduces catheter colonization with a possible reduction in the risk of epidural catheter-related infection.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To determine the effects of cardiopulmonary bypass with profound hypothermic circulatory arrest (PHCA) on anterior fontanel pressure (AFP) and visual evoked potentials (VEPs), 21 neonates and infants undergoing cardiopulmonary bypass (CPB) with PHCA for surgical correction of congenital heart defects were studied. Mean (± SD) minimum nasopharyngeal, esophageal, and rectal temperatures of 16.4 ± 2.2, 11.2 ± 2.7, and 17.7 ± 1.9°C, respectively, were achieved for a mean duration of PHCA of 51.6 ± 18.7 min. AFP increased significantly above pre-CPB values for the first 21.7 ± 8.1 min of rewarming. The duration of this increase in AFP was related logarithmically and directly to the product of the nasopharyngeal temperature (NPT) at the end of PHCA and the duration of PHCA (r2= 0.82,P< 0.0001). Nineteen of these patients had simultaneous monitoring of VEPs. The latency of both the N70 and P100 components of the VEPs increased as temperature decreased. The cerebral perfusion pressure was linearly and inversely related to the AFP (r2= 0.72,P< 0.01). The VEPs disappeared at a nasopharyngeal temperature (NPT) of 18.9 ± 2.8°C and reappeared after 21.9 ± 8.8 min post-PHCA at an NPT of 32.8 ± 1.4°C. There was no significant difference between duration of increased AFP (20.9 ± 8.1 min) and the duration of absence of VEPs during the post-PHCA period. The duration of increased AFP correlated linearly and directly with the duration of absence of VEPs (r2= 0.84,P< 0.005). These data demonstrate that transient neurophysiologic dysfunction occurs after PHCA. This dysfunction is related to the duration of elevation of the AFP and cannot be explained solely by a temperature effect.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To document the comparability of cerebral blood flow (CBF) values determined by quantification of133Xe washout after either intravenous or intracarotid administration, 12 patients undergoing elective carotid endarterectomy anesthetized with N2O/O2and either isoflurane or halothane were studied. Scintillation counters were placed over the middle cerebral artery territory ipsilateral to the operated carotid artery. CBF was measured by the intravenous method during dissection of the carotid sheath and was calculated as the initial slope index from head washout curves collected for 11 min after injection of 10–20 mCi133Xe in saline into a large vein. Immediately prior to carotid occlusion, CBF was determined by direct injection of 1 mCi133Xe in saline into either the internal carotid artery or the common carotid artery with the external carotid artery occluded. For the intracarotid injections, the initial slope was calculated from the 1st min of washout. Data were analyzed by linear regression and analysis of variance. Values are expressed as mean ± SD. The mean CBF for intravenous and intracarotid methods were both 29 ± 10 ml·100 g-1·min-1. The correlation between CBF measured by intravenous and intracarotid methods was excellent and was described by the line y = x + 0.6, r = 0.92. We conclude that in the flow range studied, the intravenous technique may be applied to measure CBF in physiologically stable situations in which direct intracarotid injection is not feasible.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Intraoperative segmental wall motion abnormalities (SWMA) detected by transesophageal echocardiography (TEE) are sensitive, but not always specific, markers of myocardial ischemia. To determine their incidence, characteristics, and relation to postoperative cardiac morbidity, we continuously recorded the left ventricular short-axis view and 12-lead ECG in 156 high-risk patients undergoing non-cardiac surgery. Monitoring was clinically blinded. Wall motion was scored at predefined clinical, hemodynamic, and ECG events and at periodic intervals (26 ± 11 samples per patient). We detected 44 episodes of new or worsened SWMA in 32 patients (20%). The severity of most episodes was limited to severe hypokinesis (24/44, 55%) followed by akinesis (16/44, 36%) and dyskinesis (4/44, 9%). The remaining 124 patients had normal wall motion or only mild hypokinesis (56/156, 36%) or chronic SWMA (68/156, 44%). The incidence of new SWMA did not differ for patients with known coronary artery disease (CAD) and those with cardiac risk factors only (22%vs.19%,P= not significant), although CAD patients had a significantly greater incidence of chronic SWMA (62%vs.41%,P= 0.02). The incidence of new or worsened SWMA was significantly greater during aortic vascular surgery (38%vs.17%,P= 0.05). Approximately 40% of all new TEE changes occurred in the absence of either an apparent clinical event or a significant change in systolic blood pressure or heart rate. Ten patients had new or worsened SWMA persisting until the end of surgery, 8 with new akinesis, only 1 developing myocardial infarction. The distribution of new or worsened SWMA and significant intraoperative ST-T changes (n= 19) in this cohort was discordant: temporal overlap between modalities was present in only 5 patients. Major cardiac complications occurred in 5 patients (3.2%), all of whom underwent peripheral vascularization. All patients with cardiac complications and new or worsened SWMA also had intraoperative or early postoperative ST-T changes. We conclude that: 1) continuous TEE recording with offline analysis in this high-risk group of patients revealed a relatively low incidence of new or worsened SWMA (20%), most episodes of which were characterized by severe hypokinesis (55%); 2) episodes were more common in patients undergoing aortic vascular surgery; 3) approximately 40% of episodes were unaccompanied by clinical events or significant hemodynamic changes; 4) episodes were poorly correlated with postoperative cardiac complications; and 5) the discordant relation between TEE and ECG changes observed here necessitates careful monitoring of the ECG when TEE is used clinically.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID