ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundAlthough the ulnar nerve is the most frequent site of perioperative neuropathy, the mechanism remains undefined. The ulnar nerve appears particularly susceptible to external pressure as it courses through the superficial condylar groove at the elbow, rendering it vulnerable to direct compression and ischemia. However, there is disagreement among major anesthesia textbooks regarding optimal positioning of the arm during anesthesia.MethodsTo determine which arm position (supination, neutral orientation, or pronation) minimizes external pressure applied to the ulnar nerve, we studied 50 awake, normal volunteers using a computerized pressure sensing mat. An additional group of 15 subjects was tested on an operating Table withtheir arm in 30 [degree sign], 60 [degree sign], and 90 [degree sign] of abduction, as well as in supination, neutral orientation, and pronation. To determine the onset of clinical paresthesia compared to the onset and severity of somatosensory evoked potential (SSEP) electrophysiologic changes, we studied a separate group of 16 male volunteers while applying intentional pressure directly to the ulnar nerve. Data are presented as mean (median; range).ResultsSupination minimizes direct pressure over the ulnar nerve at the elbow (2 mmHg [0; 0–23]; n = 50), compared with both neutral forearm orientation (69 mmHg [22; 0–220]; P < 0.0001), as well as pronation (95 mmHg [61; 0–220]; P < 0.0001). Neutral forearm orientation also results in significantly less pressure over the ulnar nerve compared to pronation (P <or= to 0.04). The estimated contact area of the ulnar nerve with the weight‐bearing surface was significantly (P < 0.0001) smaller in the supine position (2.2 cm2[0.5; 0–9]; n = 50) compared with both neutral orientation (5.5 cm2[5.0; 0–13]) and pronation (5.8 cm2[6; 0–12]). With the forearm in neutral orientation, ulnar nerve pressure decreased significantly (P <or= to 0.01; n = 15) as the arm was abducted at the shoulder from 0 [degree sign] to 90 [degree sign]. In the 16 male subjects tested, notable alterations in ulnar nerve SSEP signals (decrease >or= to 20% in N9‐N9′ amplitude) were detected in 15 of 16 awake males during application of intentional pressure to the ulnar nerve. However, eight of these subjects did not perceive a paresthesia, even as SSEP waveform amplitudes were decreasing 23–72%. Two of these eight subjects manifested severe decreases in SSEP amplitude (>or= to 60%).ConclusionsExtrapolating these results to the clinical setting, the supinated arm position is likely to minimize pressure over the ulnar nerve. With the forearm in neutral orientation, pressure over the ulnar nerve decreases as the arm is abducted between 30 [degree sign] and 90 [degree sign]. In addition, up to one half of male patients may fail to perceive or experience clinical symptoms of ulnar nerve compression sufficient to elicit SSEP changes.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundTo study the effect of nitecapone, a novel anti‐oxidant, on cardiac neutrophil activation during cardiopulmonary bypass in patients.MethodsIn a double‐blind, placebo controlled trial, 30 male patients undergoing coronary artery bypass grafting were randomly assigned to control (crystalloid cardioplegia, n = 15) and nitecapone groups (cardioplegia supplemented with nitecapone, n = 15). Leukocyte differential counts, neutrophil and monocyte CD11b and L‐selectin expressions and neutrophil hydrogen peroxide production were measured in blood samples parallelly obtained from the coronary sinus and aorta before cardiopulmonary bypass and at 1, 5, and 10 min after aortic declamping. Myocardial myeloperoxidase activity was analyzed in biopsies taken at 1, 5, and 10 min after declamping.ResultsTranscoronary neutrophil difference (i.e., aorta ‐ sinus coronarius) at 1 min after aortic declamping was significantly lower in nitecapone‐treated patients (0.41 [‐0.42–0.98] x 109cells/l) than in controls (0.68 [‐0.28–2.47] x 109cells/l; P = 0.032). At 5 min after aortic declamping, significant transcoronary reduction of neutrophil hydrogen peroxide production and CD11b expression were observed in controls but not in nitecapone patients. At 24 h postoperatively, left ventricular stroke volume was better in nitecapone‐treated patients (94 [51–118] ml) than controls (66 [40–104] ml; P = 0.018). Data are median [range].ConclusionNitecapone added to cardioplegia solution reduces cardiac neutrophil accumulation and transcoronary neutrophil activation during clinical cardiopulmonary bypass. Reflected by better left ventricular stroke volume, nitecapone treatment may be an additional way of reducing the deleterious effects of neutrophil activation during cardiopulmonary bypass.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundPlatelet dysfunction is a major contributor to bleeding after [1] cardiopulmonary bypass (CPB), yet it remains difficult to diagnose. A point‐of‐care monitor, the platelet‐activated clotting time (PACT), measures accelerated shortening of the kaolin‐activated clotting time by addition of platelet activating factor. The authors sought to evaluate the clinical utility of the PACT by conducting serial measurements of PACT during cardiac surgery and correlating postoperative measurements with blood loss.MethodsIn 50 cardiac surgical patients, blood was sampled at 10 time points to measure PACT. Simultaneously, platelet reactivity was measured by the thrombin receptor agonist peptide‐induced expression of P‐selectin, using flow cytometry. These tests were temporally analyzed. PACT values, P‐selectin expression, and other coagulation tests were analyzed for correlation with postoperative chest tube drainage.ResultsPACT and P‐selectin expression were maximally reduced after protamine administration. Changes in PACT did not correlate with changes in P‐selectin expression at any time interval. Total 8‐h chest tube drainage did not correlate with any coagulation test at any time point except with P‐selectin expression after protamine administration (r = ‐0.4; P = 0.03).ConclusionsThe platelet dysfunction associated with CPB may be a result of depressed platelet reactivity, as shown by thrombin receptor activating peptide‐induced P‐selectin expression. Changes in PACT did not correlate with blood loss or with changes in P‐selectin expression suggesting that PACT is not a specific measure of platelet reactivity.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundThe authors' previous study demonstrated that xenon (Xe) and nitrous oxide (N2O) in combination with sevoflurane can attenuate cardiovascular responses to skin incision. To quantitatively evaluate their suppressive effects on cardiovascular responses, the authors compared the MAC‐BAR (minimum alveolar concentration that blocks adrenergic or cardiovascular response to incision) values of sevoflurane when administered with Xe or N2O.MethodsForty‐three patients received sevoflurane with one of three anesthetics; 1 MAC Xe, 0.7 MAC Xe and 0.7 MAC N2O. The MAC‐BAR of sevoflurane was determined in each anesthetic using the "up and down" method. The response was considered positive if the heart rate or mean arterial pressure increased 15% or more. The end‐tidal sevoflurane concentration given to the next patient was increased or decreased by 0.3 MAC if the response was positive or negative in the previous patient, respectively. The MAC‐BAR was calculated as the mean of four independent cross‐over responses.ResultsThe MAC‐BAR of sevoflurane, including the contribution of Xe or N2O, was 2.1 +/‐ 0.2 MAC and 2.7 +/‐ 0.2 MAC when administered with 1 MAC Xe, respectively, and 2.6 +/‐ 0.4 MAC when administered with 0.7 MAC N (2) O (mean +/‐ SD).ConclusionsAlthough 1 MAC Xe has a more potent suppressive effect on cardiovascular responses to incision than 0.7 MAC Xe or N2O, Xe and N (2) O have a similar suppressive effect at 0.7 MAC.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundThe study was designed to examine a new method of confirming proper caudal needle placement using nerve stimulation.MethodsThirty‐two pediatric patients were studied. A 22‐gauge insulated needle was inserted into the caudal canal via the sacral notch until a "pop" was felt. The needle placement was classified as correct or incorrect depending upon the presence or absence of anal sphincter contraction (S2‐S4) to electrical simulation (1 to 10 mA).ResultsThree patients were excluded, two because they inadvertently received neuromuscular blockers and one because the patient's anatomy precluded any attempt at a caudal block. The sensitivity and specificity of the test were both 100% in predicting clinical outcomes of the caudal block. Six patients had a negative stimulation test after the first attempt to place the needle. Four of these went on to receive a second attempt of needle insertion after a subcutaneous bulge or resistance to local anesthetic injection were observed. Following needle reinsertion, positive stimulation tests were elicited. These patients received the local anesthetic injection with ease and had good analgesia postoperatively. No attempt was made to reinsert the needle in the remaining two patients with a negative stimulation test, as they did not show subcutaneous bulge or resistance upon injection. These patients had poor analgesia postoperatively. The positive predictive value of the test was greater than the presence of a "pop" alone (P < 0.05) but not significantly different (P = 0.492) over the presence of "pop" and easy injection.ConclusionThis test may be used as a teaching and adjuvant tool in performing caudal block.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID