Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2001
Clinical Trial Controlled Clinical TrialThe additive pulmonary vasodilatory effects of inhaled prostacyclin and inhaled milrinone in postcardiac surgical patients with pulmonary hypertension.
Selective pulmonary vasodilation is an advantageous therapeutic strategy for cardiac surgical patients with increased pulmonary vascular resistance (PVR) and right ventricular failure. We hypothesized that milrinone, an adenosine-3',5'-cyclic monophosphate (cAMP)-selective phosphodiesterase enzyme (PDE) inhibitor may, when nebulized and inhaled, cause selective pulmonary vasodilation and potentiate the vasodilation by inhaled prostacyclin (iPGI(2)). Consequently, we investigated the hemodynamic effects of inhaled milrinone or the combination iPGI(2) + inhaled milrinone in cardiac surgical patients with postoperative mean pulmonary arterial pressure (MPAP) >25 mm Hg and PVR >200 dynes. s(-1). cm(-5). During mechanical ventilation and using a conventional nebulizing system, 9 patients inhaled incremental concentrations of milrinone (0.25, 0.5 and 1 mg/mL) in subsequent 10-min periods (Study Part 1). In the same manner, 11 patients received iPGI(2) (10 microg/mL) followed by the combination of iPGI(2) (10 microg/mL) and inhaled milrinone (1 mg/mL) (Study Part 2). Inhaled milrinone reduced PVR with a maximal effect (-20%, P < 0.001) at the largest concentration. As compared with iPGI(2) alone, iPGI(2) + inhaled milrinone caused a further and prolonged reduction of PVR (-8%, P < 0.05) and increased stroke volume (+5%, P < 0.05). Systemic vascular resistance or mean arterial pressure was not affected by inhalation of either drug(s). The authors conclude that inhalation of the cAMP-selective PDE-inhibitor milrinone selectively dilates the pulmonary vasculature without systemic effects in cardiac surgical patients with pulmonary hypertension. Furthermore, inhaled milrinone appears to potentiate and prolong the pulmonary selective vasodilatory effect of iPGI(2). Inhaled milrinone alone or combined with iPGI(2) may be an important therapeutic option in the treatment of patients with pulmonary hypertension and right ventricular failure. ⋯ Pulmonary hypertension may cause or aggravate right heart failure. IV vasodilators reduce systemic blood pressure and might thereby further impair coronary perfusion and right heart performance. In the present study of cardiac surgical patients with pulmonary hypertension, selective pulmonary vasodilation without systemic effects was induced by nebulized, inhaled vasodilators.
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Anesthesia and analgesia · Dec 2001
The predictive value of ventricular fibrillation electrocardiogram signal frequency and amplitude variables in patients with out-of-hospital cardiac arrest.
We evaluated ventricular fibrillation frequency and amplitude variables to predict successful countershock, defined as pulse-generating electrical activity. We also elucidated whether bystander cardiopulmonary resuscitation (CPR) influences these electrocardiogram (ECG) variables. In 89 patients with out-of-hospital cardiac arrest, ECG recordings of 594 countershock attempts were collected and analyzed retrospectively. By using fast Fourier transformation analysis of the ventricular fibrillation ECG signal in the frequency range 0.333-15 Hz (median [range]), median frequency, dominant frequency, spectral edge frequency, and amplitude were as follows: 4.4 (2.4-7.5) Hz, 4.0 (0.7-7.0) Hz, 7.7 (3.7-13.7) Hz, and 0.94 (0.24-1.95) mV, respectively, before successful countershock (n = 59). These values were 3.8 (0.8-7.7) Hz (P = 0.0002), 3.0 (0.3-9.7) Hz (P < 0.0001), 7.3 (2.0-14.0) Hz (P < 0.05), and 0.53 (0.03-3.03) mV (P < 0.0001), respectively, before unsuccessful countershock (n = 535). In patients in whom bystander CPR was performed (n = 51), ventricular fibrillation frequency and amplitude before the first defibrillation attempt were higher than in patients without bystander CPR (n = 38) (median frequency, 4.4 [2.4-7.5] vs 3.7 [1.8-5.3] Hz, P < 0.0001; dominant frequency, 3.8 [0.9-7.7] vs 2.6 [0.8-5.9] Hz, P < 0.0001; spectral edge frequency, 8.4 [4.8-12.9] vs 7.2 [3.9-12.1] Hz, P < 0.05; amplitude, 0.79 [0.06-4.72] vs 0.67 [0.16-2.29] mV, P = 0.0647). Receiver operating characteristic curves demonstrate that successful countershocks will be best discriminated from unsuccessful countershocks by ventricular fibrillation amplitude (3000-ms epoch). At 73% sensitivity, a specificity of 67% was obtained with this variable. ⋯ In patients with out-of-hospital cardiac arrest, successful countershocks will be best discriminated from unsuccessful countershocks by ventricular fibrillation amplitude (3000-ms epoch). At 73% sensitivity, a specificity of 67% was obtained with this variable.
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Anesthesia and analgesia · Dec 2001
Risk factors for ischemic optic neuropathy after cardiopulmonary bypass: a matched case/control study.
Visual loss (acuity or field) secondary to ischemic optic neuropathy (ION) is a rare but devastating complication of cardiac surgery involving cardiopulmonary bypass (CPB). We determined clinical features and risk factors for ION by a retrospective time-matched, case-control study. ION was identified in 17 (0.06%) patients out of 27,915 patients who underwent CPB between January 1, 1976, and December 31, 1994. For each ION patient, two patients who underwent CPB exactly 2 wk before the ION patient were selected as controls. Data were analyzed by using conditional logistic regression with the 1:2 matched-set feature of 17 cases and 34 controls. Two-tailed P values < or =0.05 were considered significant. From bivariate analysis, smaller minimum postoperative hemoglobin concentration (odds ratio [OR] = 1.9, P = 0.047) and the presence of atherosclerotic vascular disease (OR = 7.0, P = 0.026) were found to be independently associated with ION after CPB, as were smaller minimum postoperative hemoglobin concentration (OR = 2.2, P = 0.027) and preoperative angiogram within 48 h of surgery (OR = 7.2, P = 0.042). In ION patients, 13 (76.5%) of 17 experienced a minimum postoperative hemoglobin value of < 8.5 g/dL, whereas only 14 (41.2%) of 34 control patients experienced values < 8.5 g/dL. ⋯ Patients with clinically significant vascular disease history or preoperative angiogram may be at increased risk for ischemic optic neuropathy after cardiac surgery, especially if the hemoglobin remains low in the postoperative period.
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Anesthesia and analgesia · Dec 2001
Comparative StudyThe comparative electrophysiologic and hemodynamic effects of a large dose of ropivacaine and bupivacaine in anesthetized and ventilated piglets.
Ropivacaine is less potent and less toxic than bupivacaine. We administered these two local anesthetics in a cardiac electrophysiologic model of sodium thiopental-anesthetized and ventilated piglets. After assessing the stability of the model, bupivacaine (4 mg/kg) and ropivacaine (6 mg/kg) were given IV in two groups (n = 7) of piglets. No alteration in biological variables was reported throughout the study. Bupivacaine and ropivacaine similarly decreased mean aortic pressure from 99 +/- 22 to 49 +/- 31 mm Hg and from 87 +/- 17 to 58 +/- 28 mm Hg, respectively, and decreased the peak of the first derivative of left ventricular pressure from 1979 +/- 95 to 689 +/- 482 mm Hg/s and from 1963 +/- 92 to 744 +/- 403 mm Hg/s, respectively. Left ventricular end-diastolic pressure was similarly increased from 6 +/- 5 to 9 +/- 5 mm Hg and from 6 +/- 4 to 12 +/- 4 mm Hg, respectively. Bupivacaine and ropivacaine similarly lengthened the cardiac cycle length (R-R; from 479 +/- 139 to 706 +/- 228 ms and from 451 +/- 87 to 666 +/- 194 ms, respectively), atria His (from 71 +/- 15 to 113 +/- 53 ms and from 64 +/- 6 to 86 +/- 10 ms, respectively), and QTc (QTc = QT x R-R(-0.5), Bazett formula; from 380 +/- 71 to 502 +/- 86 ms and from 361 +/- 33 to 440 +/- 56 ms, respectively) intervals. Bupivacaine altered to a greater extent the PQ (the onset of the P wave to the Q wave of the QRS complex) (from 97 +/- 20 to 211 +/- 60 ms versus from 91 +/- 8 to 145 +/- 38 ms, P < 0.05), QRS (from 58 +/- 3 to 149 +/- 34 ms versus from 60 +/- 5 to 101 +/- 17 ms, P < 0.05), and His ventricle interval (from 25 +/- 4 to 105 +/- 30 ms vs from 25 +/- 4 to 60 +/- 30 ms, P < 0.05) than ropivacaine. A 6 mg/kg ropivacaine dose induced similar hemodynamic alterations as 4 mg/kg bupivacaine. However, bupivacaine altered the variables of ventricular conduction (QRS and His ventricle) to a greater extent. ⋯ A 6 mg/kg ropivacaine dose induced similar hemodynamic alterations as 4 mg/kg bupivacaine. However, bupivacaine altered the variables of ventricular conduction (QRS and His ventricle) to a greater extent.
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Anesthesia and analgesia · Dec 2001
Case ReportsGeneralized tonic-clonic activity after remifentanil administration.
This is the first report of seizure-like activity in an adult who received remifentanil. This report confirms that opioid administration can be associated with generalized tonic-clonic seizure-like activity. It is suggested that this reaction could be referred to as the "opioid-seizure syndrome."