Incidence of arrhythmias after thoracic surgery: thoracotomy versus video-assisted thoracoscopy.

PURPOSE: Atrial arrhythmias, especially supraventricular tachycardia (SVT) and atrial fibrillation, are common after thoracotomy and lung surgery. There are few existing data on the incidence of postoperative arrhythmias after video-assisted thoracoscopy (VAT). The purpose of the present investigation was to retrospectively determine the incidence of postoperative arrhythmias in patients who underwent VAT compared with those who underwent thoracotomy, and which factors are associated with an increased risk for arrhythmias in both groups. DESIGN: A retrospective investigation. SETTING: A metropolitan university hospital. PARTICIPANTS: The medical records of 124 patients who underwent thoracotomy and 81 patients who underwent VAT over a 2-year period were reviewed. MEASUREMENTS AND MAIN RESULTS: There was a 17% incidence of atrial arrhythmias after thoracotomy and 10% after VAT, but the difference was not statistically significant. In both groups, atrial fibrillation was the most common atrial arrhythmia. CONCLUSION: Patients receiving digoxin were at higher risk for postoperative arrhythmias. Patients older than 65 years were at risk for arrhythmias after thoracotomy and patients older than 80 years were at risk for arrhythmias after VAT. Patients who had postoperative arrhythmias had prolonged hospital stays compared with patients who did not have arrhythmias.

Role of zatebradine and propranolol in attenuation of tachycardia produced by dobutamine in pigs.

BACKGROUND: Zatebradine is a new specific bradycardiac agent that selectively slows the depolarization in the pacemaker cells of the sinoatrial node. The purpose of our investigation was to determine whether the tachycardia induced by dobutamine can be attenuated by the administration of zatebradine. The results were compared with those produced by propranolol, which is used in the treatment of sinus tachycardia. METHODS: Twelve pigs were anesthetized with sodium pentobarbital, intubated, and ventilated. After baseline hemodynamic measurements were obtained, dobutamine was administered until the heart rate reached 25% above baseline. Animals were randomized to one of two groups. Group I received zatebradine, 0.5 mg/kg i.v., and Group II received propranolol, 0.5 mg/kg i.v. RESULTS: Dobutamine 10 micrograms.kg-1.min-1 increased the heart rate (FIR) by 25%, and increased mean arterial blood pressure (MAP) left ventricular (LV) dp/dt, and cardiac output (CO) (P < 0.05). Zatebradine decreased the HR to baseline (P < 0.05) without affecting left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), LV dP/dt, or CO. Stroke volume (SV) increased significantly (P < 0.05). Propranolol also reduced HR to baseline, but decreased LV dP/dt, LVSP, CO, and SV (P < 0.05). CONCLUSION: Zatebradine effectively attenuates the tachycardia caused by dobutamine in anesthetized pigs, without reducing cardiac performance.

Incidence of malposition of polyvinylchloride and red rubber left-sided double-lumen tubes and clinical sequelae.

Currently, fiberoptic bronchoscopy (FB) is recommended for correct positioning of double-lumen endobronchial tubes (DLTs) because of the high incidence of malpositions not appreciated by clinical signs. The aims of this study were to assess whether clinical signs allow accurate confirmation of adequate positioning with left red rubber (RR) or polyvinyl-chloride (PVC) double-lumen tubes and to compare the incidence of malpositions between the two tubes. Another goal was to assess whether these malpositions, not appreciated by clinical assessment, adversely affected outcome. Twenty-one adult patients scheduled for elective thoracic surgery were randomly assigned to the RR (11 patients) or PVC group (10 patients). After endobronchial intubation, the position of the tubes was adjusted until clinically satisfactory lung separation had been achieved. A single investigator performed all the FB assessments were performed in the supine (SUP) and lateral positions. The anesthesiologists responsible for the clinical evaluation were "blinded" to the bronchoscopic findings. While in the SUP position, the tube was "too deep" to permit visualization of the carina during tracheal bronchoscopy in 5 patients (2 RR, 3 PVC). In 17 of 21 (10 RR, 7 PVC), the bronchial cuff could not be visualized, although in 1 patient (RR group), the cuff was overinflated and bulged out to partially obstruct the right main bronchus orifice. Bronchial bronchoscopy showed 4 of 11 patients in the RR group in whom the left upper lobe orifice was occluded compared with 1 only in the PVC group.(ABSTRACT TRUNCATED AT 250 WORDS)

Esmolol and intraoperative myocardial ischemia: a double-blind study.

Forty patients scheduled to undergo elective myocardial revascularization were included in a randomized, double-blind, placebo-controlled study to evaluate any influence of esmolol on the incidence of myocardial ischemia. Calibrated recordings of ECG leads II and V5 were continuously monitored with the QMED Monitor One TC (Qmed Inc, Clark, NJ) from the time of arrival in the operating room holding area through the induction of anesthesia, using a high-dose opioid technique, and until the initiation of cardiopulmonary bypass. One group received a bolus of esmolol, 1.0 mg/kg, followed by a continuous infusion of 100 micrograms/kg/min. The other group received a bolus and infusion of saline placebo of equal volume. The incidence of myocardial ischemia was not significantly different between the groups on arrival in the holding area, or at any study point. Heart rate, mean arterial pressure, and the number of patients developing myocardial ischemia during the course of the study also did not differ significantly between the groups. There were significant decreases in heart rate and mean arterial pressure compared with the awake baseline values in both groups during multiple study points. It is concluded that esmolol was ineffective at treating preexisting or new-onset myocardial ischemia at this dosage in this clinical setting.

Arrhythmogenic potential of dopexamine hydrochloride during halothane anaesthesia in dogs.

Dopexamine hydrochloride (Dopacard) is the novel synthetic catecholamine designed for use in the acute management of a low cardiac output status. In addition to dopaminergic receptor stimulation, dopexamine hydrochloride is a potent beta 2 adrenoceptor agonist with negligible direct beta 1 and no alpha adrenergic effect. The objective of this study was to compare the arrhythmogenic effects of dopexamine hydrochloride and dopamine in dogs anaesthetized with halothane (1.2 MAC). The starting dose for dopexamine hydrochloride was 3.5 micrograms.kg-1.min-1 and for dopamine was 5 micrograms.kg-1.min-1. Concentrations of the drugs were increased until four or more premature ventricular contractions within 15 seconds were produced. All dogs developed ventricular tachycardia when dopamine was administered in concentrations ranging between 18-20 micrograms.kg-1.min-1. Unlike dopamine, dopexamine hydrochloride even at concentrations as high as 50 micrograms.kg-1.min-1 did not induce any atrial or ventricular ectopic beats. Lack of beta 1 and alpha adrenergic agonist effects is a likely explanation for low arrhythmogenicity of dopexamine hydrochloride. Both drugs increase cardiac output; dopexamine hydrochloride primarily by a dose-related increase in heart rate and increased afterload. At the maximal concentration dopexamine hydrochloride increased heart rate from 114 to 150 beat.min-1, mean arterial pressure decreased from 81 mmHg to 45 mmHg and SVR decreased from 2418 to 962 dyne.sec-1cm-5. Myocardial contractility increased only moderately, as evaluated by dP/dt, which increased from 1290 to 1696 mmHg.sec-1. Dopamine had a more marked inotropic effect: the dP/dt increased, at the maximal concentration, from 1480 to 2570 mmHg.sec-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Transoesophageal echocardiography and the intraoperative diagnosis of left atrial invasion by carcinoid tumour.

A 41-yr-old woman with pulmonary carcinoid tumour presented for thoracotomy and lung resection. However, intraoperative transoesophageal echocardiography (TEE) revealed that the tumour had invaded the left atrium, and the planned resection was aborted to allow resection under cardiopulmonary bypass at a later date. Although the incidence of cardiac involvement by lung cancer at the time of pulmonary resection is unknown, transoesophageal echocardiography can be useful in identifying the extension of hilar lung tumours. This should preferentially be done preoperatively, but can be done intraoperatively as described in this case report.

Intrathecal morphine during thoracotomy, Part I: Effect on intraoperative enflurane requirements.

The ability of intrathecal morphine to reduce the anesthetic requirements during thoracotomy was investigated. Twenty-four patients scheduled for thoracic surgery were studied. Anesthesia was induced with thiamylal sodium, 4 mg/kg, fentanyl, 100 micrograms, and 100 mg of succinylcholine. Prior to skin incision, 12 patients received intrathecal injection of 12 micrograms/kg of preservative-free morphine sulfate (ITM), while the remaining 12 patients served as controls. The ITM was given undiluted at the L3-4 or L4-5 level. Anesthesia was maintained solely with enflurane, titrated to keep mean arterial pressure within 15% of the preoperative values. Vecuronium was given as required for relaxation. No additional narcotics were administered. Throughout the procedure, end-tidal (ET) enflurane concentration was recorded at 15-minute intervals from the mass spectrometer (Perkin Elmer). The intraoperative mean ET concentration of enflurane was significantly reduced in the ITM group beginning 1 hour after the injection (1.19 +/- .45% in the control group versus 0.73 +/- 0.08% in the ITM group). The enflurane requirements, expressed as percent end-tidal enflurane/hour, were significantly less in the ITM group for the duration of the procedure (0.8 +/- .17 v 1.08 +/- .22, respectively). In conclusion, when administered prior to skin incision for post-thoracotomy pain control, intrathecal morphine reduces intraoperative enflurane requirements.

Intrathecal morphine during thoracotomy, Part II: Effect on postoperative meperidine requirements and pulmonary function tests.

The ability of intrathecal morphine (ITM) to reduce post-thoracotomy pain and meperidine requirements was investigated. Thirty adult patients scheduled for thoracic surgery were studied. Following induction with thiamylal sodium and succinylcholine, anesthesia was maintained with 100 micrograms of fentanyl, vecuronium, and enflurane. Prior to skin incision, 16 patients received intrathecal morphine, 12 micrograms/kg, injected at the L3-4 or L4-5 level. The other 14 patients were controls. Postoperatively, patients were evaluated for pain scores and the total doses of meperidine required over 24 hours. The patients in the ITM group required significantly less meperidine compared to the control group (59 +/- 68 v 167 +/- 97 mg, respectively) and had lower pain scores (1.4 +/- 1.1 v 2.4 +/- 0.9 mg, respectively). There were no serious side effects attributable to ITM. It is concluded that ITM is an effective adjunctive treatment for control of post-thoracotomy pain.