Forty patients undergoing elective thoracotomy were studied to assess the possibility of predicting PaO2 during one-lung ventilation (OLV) when continuous positive airway pressure (CPAP) was applied to the nondependent lung. The first 20 patients were studied retrospectively and the three most significant independent variables that correlated with PaO2 during OLV with CPAP were: side of operation (P = 0.04), FEV1/FVC ratio (P = 0.01), and the intraoperative PaO2 during two-lung ventilation (P = 0.0002). By the method of multiple linear regression, these three variables were used to construct a predictive equation for PaO2 during OLV with CPAP. The second 20 patients were studied prospectively and the predicted PaO2 correlated significantly with the observed PaO2 during OLV with CPAP (r = 0.86, P less than 0.001). Therefore, it is concluded that the PaO2 during OLV with CPAP can be predicted using routinely available data.
A MIODARONE, a class III antiarrhythmic agent, has been implicated as a cause of cardiovascular instability during anesthesia.is3 Two major side effects of amiodarone include bradyarrhythmias and low systemic vascular resistance (SVR). Profound hypotension can sometimes result from either of these side effects. Electrical pacing is the treatment of choice for the dysrhythmia, and angiotensin may be the drug of choice for treating the low SVR.’ A patient taking amiodarone before cardiac surgery is reported. An angiotensin infusion was used to reverse marked hypotension that developed during cardiopulmonary bypass (CPB), and was continued to wean the patient from CPB and to maintain an adequate SVR in the postCPB period.
Arterial blood gas measurement is frequently performed in critically ill patients to diagnose and monitor acute respiratory failure. At a given metabolic rate, carbon dioxide partial pressure (Paco2) is entirely determined by CO2 elimination through ventilation. Transcutaneous partial pressure of carbon dioxide (PtcCO2) monitoring permits a noninvasive and continuous estimation of arterial CO2 tension (Paco2). The accuracy of PtcCO2, however, has not been well studied.To assess the accuracy of different CO2 monitoring methods, we compared PtcCO2 and end-tidal CO2 concentration (EtCO2) to Paco2 measurements in nonintubated intensive care unit (ICU) patients with acute respiratory failure.During a 2-month period, we conducted a prospective observational cohort study in 25 consecutive nonintubated and spontaneously breathing patients admitted to our ICU. Arterial blood gases were measured at study inclusion, 30, 60, and 120 minutes later. At each sampling time, EtCO2 was continuously monitored using a Philips Smart Capnoline Plus, and PtcCO2 was measured using was measured using SenTec device. The aim of the study was to assess agreement between PtcCO2 and Paco2 and between EtCO2 and Paco2 in nonintubated ICU patients with acute respiratory failure. Bland-Altman techniques and Pearson correlation coefficients were used. The differences over time (at 30, 60, and 120 minutes) between Paco2 and EtCO2 and between PtcCO2 and Paco2 were evaluated using 1-way analysis of variance.Transcutaneous partial pressure of carbon dioxide and Paco2 were well correlated (R = 0.97), whereas the correlation between EtCO2 and Paco2 was poor (R = 0.62) probably due to the presence of an alveolar dead space in a few patients, most notably in the group with chronic obstructive pulmonary disease. The difference over time remained stable for both Paco2 vs EtCO2 (analysis of variance; P = .88) and Paco2 vs PtcCO2 (P = .93).We found large differences between EtCO2 and Paco2 in spontaneously breathing nonintubated ICU patients admitted for acute respiratory failure. Our study argues against the use of EtCO2 monitoring in such patients but raises the possibility that PtcCO2 measurement may provide reasonable estimates of Paco2.
During the 22 years since Barnard’s historic operation, numerous clinical studies and advancements in basic science research have allowed significant breakthroughs in cardiothoracic organ transplantation. As experience with heart transplantation grew, surgical options for patients with high pulmonary vascular resistance and right ventricular failure were being investigated. In 1981, the Stanford group successfully performed the first combined heart and lung transplantation.’ The patient with end-stage pulmonary disease and normal cardiac function presents thoracic surgeons with a different set of challenges. The first human lung transplant was performed by Hardy et al in 1963.2 During the following 20 years, approximately 50 lung transplant operations were performed, the longest patient survival being 8 months.3 Because of this poor long-term survival rate, lung transplantation was performed only rarely until the mid-1980s. With the
Enoximone belongs to a new class of noncatecholamine-positive inotropes, which selectively inhibit phosphodiesterase type III and increase cyclic AMP (cAMP). This study was performed in 30 coronary artery surgery patients with impaired myocardial function (ejection fraction [EF] < 50%). The study's two purposes were to investigate the hemodynamic effects of enoximone, 0.5 mg/kg, administered following induction of anesthesia (phase I), and to assess whether enoximone can potentiate the actions of sympathomimetic agents during weaning from cardiopulmonary bypass (CPB) (phase II). Starting with already reduced hemodynamics, induction of anesthesia led to a further deterioration of blood pressure and cardiac output (CO). Administration of enoximone produced a significant increase in cardiac index (CI) (+47%), whereas pulmonary capillary wedge pressure (PCWP) (−37%), pulmonary artery pressure (PAP) (−17%). and systemic vascular resistance (SVR) (−17%) were significantly reduced. Heart rate (HR) was not increased, and no dysrhythmiss occurred during the investigation. The hemodynamic effects were maintained for 30 minutes until the start of the operation. In phase II, where weaning from CPB was not possible without pharmacological support, either enoximone (0.5 mg/kg) + epinephrine (0.1 gg/kg/min) or only epinephrine (same dosage) was randomly selected. Weaning was successful in both groups, but the combined therapy produced a larger increase in CI and a more pronounced decrease of the elevated filling pressure (PCWP). PAP was not changed in the combined therapy group, but increased in the patients receiving epinephrine alone. It is concluded that enoximone has beneficial hemodynamic effects in the perioperative period, and that potentiation of the effects of epinephrine in severe heart failure may be one of the drug's most useful features.
This study was performed in 11 patients undergoing cardiac surgery during cardiopulmonary bypass (CPB). A Bentley-10 oxygenator (American Bentley, Irvine, CA) was used during bypass, and 1,500 mL of Ringer's solution was used to prime the oxygenator. A perfusion flow of 2.4 L/min/m2 was used, and an equivalent flow of 100% oxygen was added to the oxygenator. The mixed venous oxygen saturation (SvO2) was monitored by continuous in-line venous oximetry using the Bentley Oxy-Stat Meter. Body temperature and SvO2 measurements were made at the venous blood port of the oxygenator. The authors investigated the correlation between SvO2 and changes of body temperature, perfusion flow, and hematocrit values. SvO2 correlated inversely, in a linear fashion, with the body temperature. The SvO2 was markedly decreased after rewarming, and was significantly affected during normothermia by changes in perfusion flow rates and hematocrit levels. An adequate SvO2 was found when the flow was greater than 2.4 L/min/m2 and the hematocrit was greater than 20%. In-line oximetry can help to optimize perfusion during CPB and to detect episodes of desaturation.
The influence of the degree of sympathetic nervous system activation on the cardiovascular effects of dopamine was studied during abdominal aortic surgery in 13 patients. The arterial plasma norepinephrine concentration (NE) was used as an index of sympathetic nervous system activity. During anesthesia with nitrous oxide and fentanyl, 7 patients (group 1) had a NE above 700 pg/mL and an increased mean arterial pressure (MAP) compared with the preanesthetic level (150 +/- 6 v 117 +/- 10 mm Hg; p less than 0.01, mean +/- SEM). The other 6 patients (group 2) had no significant change in MAP compared with the preanesthetic MAP (119 +/- 7 v 105 +/- 4 mm Hg). Dopamine, 4 micrograms/kg/min, decreased MAP in group 1 by 19% (150 +/- 6 to 121 +/- 8 mm Hg; P less than 0.05) because of a 32% +/- 9% decrease (P less than 0.05) in systemic vascular resistance. MAP was not altered by dopamine in group 2 (119 +/- 7 v 123 +/- 6 mm Hg; not significant). Following termination of dopamine, the anesthetic was supplemented with thoracic epidural anesthesia (TEA). This reduced MAP to 65 +/- 7 mm Hg (P less than 0.01) and 56 +/- 3 mm Hg (P less than 0.01), and NE to 441 +/- 76 (P less than 0.05) and 235 +/- 45 pg/mL (P less than 0.05) in groups 1 and 2, respectively. During TEA, dopamine increased MAP similarly in both groups, to 85 +/- 7 mm Hg (P less than 0.01) and 82 +/- 9 mm Hg (P less than 0.05), respectively. In conclusion, dopamine, at the same dosages, counteracted hypertension during general anesthesia and counteracted hypotension during general anesthesia combined with TEA.
