General Anesthesia For Cardiac Surgery Research Articles

Intrathecal Morphine Plus General Anesthesia in Cardiac Surgery: Effects on Pulmonary Function, Postoperative Analgesia, and Plasma Morphine Concentration

OBJECTIVES:To evaluate the effects of intrathecal morphine on pulmonary function, analgesia, and morphine plasma concentrations after cardiac surgery.INTRODUCTION:Lung dysfunction increases morbidity and mortality after cardiac surgery. Regional analgesia may improve pulmonary outcomes by reducing pain, but the occurrence of this benefit remains controversial.METHODS:Forty-two patients were randomized for general anesthesia (control group n=22) or 400 μg of intrathecal morphine followed by general anesthesia (morphine group n=20). Postoperative analgesia was accomplished with an intravenous, patient-controlled morphine pump. Blood gas measurements, forced vital capacity (FVC), forced expiratory volume (FEV), and FVC/FEV ratio were obtained preoperatively, as well as on the first and second postoperative days. Pain at rest, profound inspiration, amount of coughing, morphine solicitation, consumption, and plasma morphine concentration were evaluated for 36 hours postoperatively. Statistical analyses were performed using the repeated measures ANOVA or Mann-Whiney tests (*p<0.05).RESULTS:Both groups experienced reduced FVC postoperatively (3.24 L to 1.38 L in control group; 2.72 L to 1.18 L in morphine FEV1 (p=0.085), group), with no significant decreases observed between groups. The two groups also exhibited similar results for FEV1/FVC (p=0.68) and PaO2/FiO2 ratio (p=0.08). The morphine group reported less pain intensity (evaluated using a visual numeric scale), especially when coughing (18 hours postoperatively: control group= 4.73 and morphine group= 1.80, p=0.001). Cumulative morphine consumption was reduced after 18 hours in the morphine group (control group= 20.14 and morphine group= 14.20 mg, p=0.037). The plasma morphine concentration was also reduced in the morphine group 24 hours after surgery (control group= 15.87 ng.mL−1 and morphine group= 4.08 ng.mL−1, p=0.029).CONCLUSIONS:Intrathecal morphine administration did not significantly alter pulmonary function; however, it improved patient analgesia and reduced morphine consumption and morphine plasma concentration.

Validation of the index of consciousness during sevoflurane and remifentanil anaesthesia: a comparison with the bispectral index and the cerebral state index

BackgroundThe purpose of this study was to validate a new level of consciousness monitor derived from the EEG, called the index of consciousness (IoC), by comparing it with the bispectral index (BIS) and the cerebral state index (CSI) during general anaesthesia for cardiac surgery using sevoflurane, remifentanil, and atracurium. MethodsAfter ethical committee approval and written patient consent, data from 35 patients [31 males, four females, age 55 (10) yr] were recorded during general anaesthesia for elective cardiac bypass surgery. All patients were induced with sevoflurane 8%, until the Observer's Assessment of Alertness and Sedation (OAAS) scale level 1 was reached, and then was set at a 1% end-tidal sevoflurane concentration. Subsequently, remifentanil and atracurium were administered, the trachea was intubated, and the procedure continued as usual. To assess accuracy, the prediction probability (Pk) was calculated both during induction and during maintenance. ResultsThe Pk values [mean (se)] for IoC, BIS, and CSI during induction were 0.90 (0.01), 0.90 (0.01), and 0.88 (0.01), respectively, whereas the corresponding Pk values during maintenance were 0.95 (0.01), 0.94 (0.01), and 0.60 (0.01). ConclusionsThe three indices performed equally well during the induction phase and were able to predict the level of consciousness of the patients satisfactorily. During maintenance, the IoC and the BIS showed good agreement with the clinical signs. The CSI was significantly influenced by the administration of atracurium; therefore, the agreement with the OAAS scale during the maintenance phase was significantly less for CSI than for IoC and BIS.

Anesthetic Induction in a Sitting Position for a Patient with Congestive Heart Failure

A 67-year-old woman with severe congestive heart failure (New York Heart Association, NYHA class IV) was set to receive general anesthesia for cardiac surgery. For several months, she had been in a constant sitting position from which the slightest change evoked dyspnea. A patient in such a condition is rarely considered a candidate for general anesthesia, because such patients are never eligible for any type of surgery other than that used to fix the heart problem itself. We report this case to explain how anesthesia was induced with the patient sitting in a crouching position and discuss other methods of induction that can probably be used in similar situations.

The use of regional anesthesia in combination with general anesthesia for cardiac surgery in children

The use of regional anesthesia in combination with general anesthesia for children undergoing cardiac surgery is the subject of a number of publications and presentations. Benefits of regional anesthesia in patients having cardiac surgery include attenuation of the neuroendocrine response to surgical stress, improved postoperative pulmonary function, enhanced cardiovascular stability, and improved postoperative analgesia. Regional anesthesia can control adverse cardiovascular reflexes in cardiac surgical patients and may facilitate early tracheal extubation, thereby reducing complications and costs associated with postoperative mechanical ventilation. These benefits must, however, be weighed against the adverse effects which may accompany the use of regional anesthesia, including hypotension, postoperative respiratory depression, and epidural hematoma formation. In this article, the benefits and risks of regional anesthesia in infants and children having open heart surgery are reviewed. In addition, specific spinal and epidural techniques currently in use are described, including management of side effects.

Epidural Anesthesia Improves Outcome and Resource Use in Cardiac Surgery: A Single-Center Study of a 1293-Patient Cohort

Thoracic epidural anesthesia (TEA) combined with general anesthesia in cardiac surgery has the potential to initiate earlier spontaneous ventilation and extubation, improved hemodynamics, less arrhythmia or myocardial ischemia, and an attenuated neurohormonal response. The aim of the current study was to characterize the correlation between TEA and postoperative resource use or outcome in a consecutive-patient cohort. The study was performed in a tertiary care, 3-surgeon, university-affiliated hospital that performs 350 to 400 cardiac surgeries per year. All 1293 adult patients who underwent cardiac surgery between July 1, 2002, and February 1, 2006, were included. Patients were assigned to anesthesiologists practicing TEA (TEA group, n = 506) or not (control group, n = 787) for cardiac surgery. The preoperative parameter values and Parsonnet scores for the 2 groups were similar. The 2 groups had the same distribution of surgery types. The TEA group presented with fewer intensive care unit (ICU) complications, such as delirium, pneumonia, and acute renal failure, and presented with better myocardial protection. The TEA group presented with a higher proportion of immediately postoperative extubations and with shorter ventilation times and ICU stays. Total ICU costs decreased from US $18,700 to $9900 per patient. Combining TEA and general anesthesia for cardiac surgery allows a significant change in anesthesia strategy. This change improves immediate postoperative outcomes and reduces the use and costs of ICU resources.

General Anesthesia in Cardiac Surgery: A Review of Drugs and Practices

General anesthesia is defined as complete anesthesia affecting the entire body with loss of consciousness, analgesia, amnesia, and muscle relaxation. There is a wide spectrum of agents able to partially or completely induce general anesthesia. Presently, there is not a single universally accepted technique for anesthetic management during cardiac surgery. Instead, the drugs and combinations of drugs used are derived from the pathophysiologic state of the patient and individual preference and experience of the anesthesiologist. According to the definition of general anesthesia, current practices consist of four main components: hypnosis, analgesia, amnesia, and muscle relaxation. Although many of the agents highlighted in this review are capable of producing more than one of these effects, it is logical that drugs producing these effects are given in combination to achieve the most beneficial effect. This review features a discussion of currently used anesthetic drugs and clinical practices of general anesthesia during cardiac surgery. The information in this particular review is derived from textbooks, current literature, and personal experience, and is designed as a general overview of anesthesia during cardiac surgery.

What is the optimal paddle force for defibrillation?

Introduction - Firm paddle pressure during defibrillation is important to minimize transthoracic impedance (TTI) and optimize trans-myocardial current. Previous European Resuscitation Council (ERC) guidelines recommended that 12 kg force should be used [1] and the more recent International Liaison Committee on Resuscitation (ILCOR) guidelines recommend 'firm' pressure [2]. The actual relationship between force and transthoracic impedance has not been established. Methods - 55 patients (36 male, 19 female) undergoing general anaesthesia for cardiac surgery were investigated. Male chests were shaved. A pair of gel pads and paddles were placed in the anterior-apical position according to the ILCOR guidelines. The endotracheal tube was opened to air and paddles instrumented with force sensors were applied to the chest wall with progressive force to a maximum of 12 kgf. The resultant TTI was recorded at 10 measurements per second to a hard drive. Results - Light pressure results in a high TTI that rapidly decreases as paddle force increases (Fig. 1). An 18.7% fall in overall TTI occurs when applying force from 0.5 to 6.0 kg. Increasing paddle force from 6 to 12 kg results in a further decrease in TTI of 3.2%. Conclusion - A minimum of 6 kg force applied to each paddle is necessary to achieve 83% of the overall decrease in TTI seen at 12 kgf. Further decrease in TTI as force is applied in excess of 6 kgf is small and a force of 12 kgf only reduces TTI by a further 3.2% compared with TTI at 6 kgf. The additional clinical benefit of applying 12 kgf as opposed to 6 kgf is questionable.

The Use of Regional Anesthesia in Combination With General Anesthesia for Cardiac Surgery in Children

The use of regional anesthesia in combination with general anesthesia for children undergoing cardiac surgery is the subject of a growing number of publications and presenta tions. Benefits of regional anesthesia in patients having car diac surgery include attenuation of the neuroendocrine response to surgical stress, improved postoperative pulmo nary function, enhanced cardiovascular stability, and im proved postoperative analgesia. To the extent that regional anesthesia facilitates early tracheal extubation in cardiac surgical patients, complications and costs associated with postoperative mechanical ventilation may be reduced. These benefits must, however, be weighed against the ad verse effects that may accompany the use of regional anes thesia, including hypotension, postoperative respiratory de pression, and epidural hematoma formation. In this article, the benefits and risks of regional anesthesia in infants and children undergoing open heart surgery are reviewed. In addition, specific spinal and epidural techniques currently in use are described, including management of side effects. Copyright © 2001 by W.B. Saunders Company.

Thoracic epidural anesthesia as an adjunct to general anesthesia for cardiac surgery: Effects on ventilation-perfusion relationships

Postoperative hypoxemia remains a serious and frequent complication after cardiac surgery. Development of atelectasis during anesthesia appears to be a major factor in producing the increase in intrapulmonary shunt and consequently impaired gas exchange after cardiopulmonary bypass. Postoperative hypoxemia can produce significant ill effects, including increase in duration of postoperative ventilation, pulmonary complications, myocardial ischemia, and neurologic impairment. These complications are associated with prolonged intensive care unit (ICU) and hospital length of stay, resulting in significant increase in cost.

Thoracic epidural anesthesia as an adjunct to general anesthesia for cardiac surgery: Effects on ventilation-perfusion relationships

Objective: To determine the effects of thoracic epidural anesthesia (TEA) on ventilation-perfusion (V A/Q) relationships, atelectasis, and oxygenation before and after coronary artery bypass graft surgery (CABG). Design: Prospective, controlled, unblinded, randomized trial. Setting: Cardiothoracic clinic at a major university referral center. Participants: Twenty-eight patients undergoing elective CABG. Interventions: Perioperative and postoperative TEA was added to general anesthesia (GA) in 14 patients, and 14 patients receiving GA alone served as controls. Measurements and Main Results: V A/Q relationships were measured by the multiple inert gas elimination technique, and, 20 hours postoperatively, atelectasis was assessed by computerized tomographic scans. Arterial and mixed venous blood gases and hemodynamic variables were measured by standard techniques. TEA per se caused no change in shunt, V A/Q matching, or oxygenation. Induction of GA in the control group and induction of TEA caused similar reductions in mean arterial pressure. The TEA patients needed less morphine analgesia postoperatively and were extubated earlier. Extubation caused significant improvement in V A/Q matching. On the first postoperative day, a slight reduction in PaCO 2 was seen in the TEA group, but no differences in shunt, V A/Q matching, or oxygenation compared with the GA group. Both groups showed extensive bilateral atelectasis. Conclusion: TEA can reduce respirator time and the need for morphine analgesics after CABG without negative effects on V A/Q matching, oxygenation, or atelectasis formation.