Bradford P. Blakeman

Pulmonary effects of methylprednisolone in patients undergoing coronary artery bypass grafting and early tracheal extubation

Numerous clinical studies suggest that methylprednisolone may facilitate early tracheal extubation after cardiac surgery, yet no investigation has rigorously examined the use of the drug in this setting.In this prospective, randomized, double-blind, placebo-controlled study, we examined the pulmonary effects of methylprednisolone in patients undergoing coronary artery bypass grafting (CABG) and early tracheal extubation. Sixty patients undergoing elective CABG and early tracheal extubation were randomized into two groups. Group MP patients received IV methylprednisolone (30 mg/kg during sternotomy and 30 mg/kg during initiation of cardiopulmonary bypass) and Group NS patients received IV placebo at the same two times. Perioperative management was standardized. Alveolar-arterial (A-a) oxygen gradient, lung compliance, shunt, and dead space were determined four times perioperatively. Postoperative tracheal extubation was accomplished at the earliest appropriate time. Both groups exhibited significant postoperative increases in A-a oxygen gradient and shunt (P < 0.000001 for each group) and significant postoperative decreases in dynamic lung compliance (P < 0.000001 for each group). Patients in Group MP exhibited significantly larger increases in postoperative A-a oxygen gradient (P = 0.001) and shunt (P = 0.001) compared with patients in Group NS. Postoperative alterations in dynamic lung compliance, static lung compliance, and dead space were not statistically significant between the groups. The time to postoperative tracheal extubation was prolonged in Group MP patients compared with Group NS patients (769 +/- 294 vs 604 +/- 315 min, respectively; P = 0.05). Methylprednisolone was associated with larger increases in postoperative A-a oxygen gradient and shunt, was unable to prevent postoperative decreases in lung compliance, and prolonged extubation time, which indicate that use of the drug may hinder early tracheal extubation in patients after cardiac surgery. Implications: Traditionally, methylprednisolone has been administered to patients undergoing cardiac surgery to decrease postoperative pulmonary dysfunction. This study revealed that the drug is associated with larger increases in postoperative alveolararterial oxygen gradient and shunt and prolonged tracheal extubation time in patients undergoing coronary artery bypass grafting, which indicate that use of the drug may hinder early tracheal extubation. (Anesth Analg 1998;87:27-33)

Intrathecal morphine for coronary artery bypass graft procedure and early extubation revisited

OBJECTIVE To determine the dose of intrathecal (IT) morphine (along with the intraoperative baseline anesthetic) that provides significant analgesia yet does not delay extubation in the immediate postoperative period in patients undergoing cardiac surgery and early extubation. DESIGN Prospective, randomized, double-blinded, placebo-controlled clinical study. SETTING Single university hospital. PARTICIPANTS Forty patients undergoing elective coronary artery bypass graft procedure and early extubation. INTERVENTIONS Twenty patients received 10 microg/kg of IT morphine, and 20 patients received IT placebo. Perioperative anesthetic management was standardized and included postoperative patient-controlled morphine analgesia. MAIN RESULTS Of the patients tracheally extubated during the immediate postoperative period, mean time to extubation was similar in patients who received IT morphine (6.8+/-2.8 h) or IT placebo (6.5+/-3.2 h). Four patients who received IT morphine had extubation substantially delayed because of prolonged ventilatory depression. There was no difference between groups in postoperative patient-controlled morphine analgesia use. CONCLUSION Even when used in conjunction with an intraoperative baseline anesthetic that allows early extubation, IT morphine (10 microg/kg) was unable to provide substantial postoperative analgesia. The risks of using IT morphine in patients undergoing cardiac surgery and early extubation may outweigh the potential benefits.

Hemodynamic effects of methylprednisolone in patients undergoing cardiac operation and early extubation

BACKGROUND Whether or not methylprednisolone is beneficial during cardiac operation remains controversial. This study examines the effects of the drug on complement activation and hemodynamics in patients undergoing cardiac operation and early extubation. METHODS Patients undergoing cardiac operation were randomized to receive either intravenous methylprednisolone (group MP) or intravenous placebo (group NS). Complement 3a (C3a) levels and hemodynamic parameters were obtained perioperatively. Extubation was accomplished at the earliest clinically appropriate time. RESULTS Both groups exhibited equivalent increases in C3a levels after exposure to bypass. Group MP exhibited increased cardiac index, decreased systemic vascular resistance, and increased shunt flow when compared to group NS. More group MP patients required hemodynamic support and group MP patients had prolonged extubation times. CONCLUSIONS Methylprednisolone was unable to attenuate complement activation and led to hemodynamic alterations (primarily vasodilation) that may hinder early extubation in patients after cardiac operations.

Myocardial metabolism and adaptation during extreme hemodilution in humans after coronary revascularization

ObjectiveThis study was designed to evaluate the oxygen transport adjustments and myocardial metabolic adaptation that occurs with different levels of hemodilution during normothermia after cardiopulmonary bypass. DesignProspective, nonrandomized study. SettingOperating room in a university hospital. PatientsEight patients with ejection fractions (>40%) undergoing elective coronary artery bypass grafting. MethodsBefore the institution of cardiopulmonary bypass, blood was withdrawn from patients to a target hematocrit of 15%. After coronary artery bypass grafting, a catheter was inserted directly into the coronary sinus. After the patients were rewarmed to 37°C, they were weaned from cardiopulmonary bypass. Hemodynamic indices were measured, as well as measurements of myocardial oxygen consumption (Vo2) and myocardial metabolism (lactate extraction and coronary sinus hypoxanthine). Measurements were made at three different hematocrit values: 15%, 20%, and 25%. Hematocrit was increased by autologous blood transfusion. Measurements and Main ResultsThe three levels of hemodilution (hematocrit: 17.4 ±PT 3.4%; 23.0 ±PT 3.7%; 27.8 ±PT 4.8%) were significantly different from baseline (hematocrit 37 ±PT 2.6%; p <.05). Oxygen delivery, which increased with autologous transfusion, exceeded 350 mL/min/m2 at each level of dilution. The myocardial Vo2 increased significantly after autologous transfusion compared with the most dilute condition (7.0 ±PT 3.7 mL/min at hematocrit 17.4% vs. 11.2 ±PT 4.8 mL/min at hematocrit 23.0% and 12.4 ±PT 4.0 mL/min at hematocrit 27.8%). This transfusion-induced increase was also true of myocardial oxygen extraction. Lactate extraction and hypoxanthine release were normal and unchanged at each level of hemodilution. Systemic oxygen extraction ratio increased with hemodilution and decreased with autologous transfusion. ConclusionsHemodilution to a hematocrit of approximately 15% is tolerated in anesthetized humans after coronary artery bypass surgery. There was no evidence of myocardial ischemia, as demonstrated by absence of S-T depression on the electrocardiogram, lactate extraction, or hypoxanthine release. In selected patients, postoperative transfusion may be based on systemic physiologic end-points, such as oxygen extraction ratio, rather than set hematocrit values.

Port-access minimally invasive cardiac surgery increases surgical complexity, increases operating room time, and facilitates early postoperative hospital discharge

Background Proposed advantages of port-access cardiac surgery have yet to be substantiated. The authors retrospectively compared patients undergoing port-access cardiac surgery with a matched group undergoing conventional cardiac surgery. Methods Forty-six patients who underwent port-access cardiac surgery were matched with 46 who underwent conventional cardiac surgery. Absolute criteria for matching included morning-of-surgery admission, procedure undergone, and care being delivered by one of two surgeons. If possible, matching included care delivered by one of two anesthesiologists. Patients were matched as closely as possible for preoperative demographic and clinical characteristics. Results All 46 pairs of patients were matched for procedure and admitted the morning of surgery. All 92 operations were performed by one of two surgeons, and 89% were performed by one of two anesthesiologists. Preoperative demographic and clinical characteristics were equivalent between groups. Compared with conventional cardiac surgery, port-access cardiac surgery increased surgical complexity (it almost tripled cardiopulmonary bypass time during coronary artery bypass grafting and increased it almost 40% during mitral valve procedures) and increased total operating room time (P < 0.0001). Port-access cardiac surgery had no beneficial effect on earlier postoperative extubation, decreased incidence of atrial fibrillation, or intensive care unit time, yet it decreased postoperative duration of stay (P = 0.029, all patients), a benefit observed primarily in patients undergoing coronary artery bypass grafting (P = 0.002). Conclusions This retrospective analysis revealed that port-access cardiac surgery increases surgical complexity, increases operating room time, has no effect on earlier postoperative extubation or decreased incidence of atrial fibrillation or intensive care unit time, and may facilitate postoperative hospital discharge (primarily in patients undergoing coronary artery bypass grafting). Properly designed prospective investigation is necessary to ascertain whether port-access cardiac surgery truly offers any benefits over conventional cardiac surgery.

Modified Konno-Rastan Procedure for Subaortic Stenosis: Indications, Operative Techniques, and Results

BACKGROUND Diffuse or unresectable subaortic stenosis (SAS) necessitates an aggressive surgical approach for the elimination of left ventricular outflow tract obstruction. In this article we report our experience with the modified Konno-Rastan procedure, with inherent preservation of the native aortic valve and annulus, in the treatment of diffuse or unresectable SAS. METHODS Sixteen children (age range, 21 months to 18 years) underwent the modified Konno-Rastan procedure through either a transventricular (n = 12) or a transatrial approach (n = 4) to the conal septum. Indications for operation were recurrent SAS (n = 3), hypertrophic obstructive cardiomyopathy (n = 3), tunnel stenosis (n = 2), SAS related to a canal (n = 3), and SAS after ventricular septal defect closure (n = 5). Eleven patients had undergone previous procedures and 5 underwent the modified Konno-Rastan procedure as their primary operation. RESULTS The mean preoperative left ventricular outflow tract gradient of 50 +/- 17 mm Hg was reduced to 3 +/- 7 mm Hg (p < 0.001) after surgical repair. Postoperative complications included sternal infection (n = 1), heart block (n = 2), mediastinal bleeding (n = 1), and renal and cerebral ischemia (n = 1). There was 1 late postoperative death caused by pneumonia 2 years after operation (6.2% mortality rate). The mean follow-up period was 62 +/- 39 months and all patients had complete relief of preoperative symptoms and were in New York Heart Association class I. One patient underwent a successful redo modified Konno-Rastan procedure 7 years after the first operation for residual left ventricular outflow tract obstruction immediately below the aortic valve. One patient is awaiting reoperation for aortic incompetence unrelated to conal enlargement 1.5 years after the first procedure. CONCLUSIONS The modified Konno-Rastan procedure represents an excellent therapy for diffuse or unresectable SAS in patients with a normal aortic valve. In addition, it produces excellent results in a limited number of patients with hypertrophic obstructive cardiomyopathy, in whom the Morrow procedure traditionally has been performed. Although it usually is performed through a transventricular approach, the modified Konno-Rastan procedure also can be performed through a transatrial approach; this is particularly useful in patients who have had previous ventricular septal defect closure associated with SAS occurring proximal to the prosthetic patch.

Somatosensory evoked potential monitoring of the brachial plexus to predict nerve injury during internal mammary artery harvest: Intraoperative comparisons of the rultract and pittman sternal retractors

Brachial plexus injury after coronary artery bypass grafting (CABG) continues to be a common problem postoperatively. With the use of somatosensory evoked potential monitoring (SSEP), neurologic integrity of the brachial plexus during internal mammary artery (IMA) harvest was assessed and the Rultract and Pittman sternal retractors were compared to determine what effect they had on SSEP characteristics. Results showed that the Rultract and Pittman retractors caused large decreases in SSEP amplitudes after insertion, (1.25 +/- 0.14 versus 0.72 +/- 0.09, P < 0.05; and 1.64 +/- 0.27 versus 0.91 +/- 0.14, P < 0.05) respectively. This decrease was noted in 85% of Rultract and 68.75% of Pittman patients, respectively. Amplitudes increased after retractor removal but never returned to baseline values. Cooley retractor placement in the patients not undergoing IMA harvest (control) produced only mild decreases in amplitude. Waveform latency increased in all groups after retractor placement, but these increases were thought to be clinically insignificant. Postoperatively, three patients in each of the IMA retractor groups had brachial plexus symptoms (18%), whereas only one patient in the control group had symptoms. Somatosensory evoked potential monitoring seems to be a sensitive intraoperative monitor for assessing brachial plexus injury during CABG. The nerve plexus seems to be most at risk for pathologic injury during retraction of the sternum for IMA harvest. Though the Rultract retractor caused greater changes in SSEP characteristics than the Pittman, no clinical outcome differences between the two could be ascertained. Using SSEP monitoring may reduce brachial plexus injury during IMA harvest by allowing early detection of nerve compromise and therapeutic interventions to alleviate the insult while under general anesthesia.

Predictors of Defibrillation Energy Requirements with Nonepicardial Lead Systems

The determinants of high defibrillation energy requirements (DER) using nonepicardial lead systems (NELS) have not been well characterized. The goal of this study was to examine prospectively the influence of clinical, radiographic, echocardiographic, and procedural variables on DER during NELS placement. Data from 100 consecutive patients undergoing attempted NELS implantation were analyzed. Transve‐nous leads, subcutaneous patches, and monophasic shock devices from two manufacturers were used. Leads were successfully positioned for testing in 95% of patients. An adequate DER (≤ 25 J) was obtained in 73 of 95 (77%) of patients. Univariate analysis identified amiodarone therapy and left ventricular mass as predictors of high DER. With multivariate analysis, amiodarone therapy was the sole significant predictor of high DER (P = 0.002, odds ratio 5.46). The 22 patients with high NELS DER also had high epicardial DER (mean 24 ± 9 J). The two patch epicardial DER was > 25 joules in 12 of 22 patients. Thus, adequate DER with monophasic shock waveforms can be obtained in most patients undergoing NELS testing. However, amiodarone therapy significantly increases the probability of obtaining high DER.

Hands-up positioning during asymmetric sternal retraction for internal mammary artery harvest: A possible method to reduce brachial plexus injury

This study compares the hands-up (HU) with the arms at side (AAS) position to determine whether one is beneficial in reducing brachial plexus stress during asymmetric sternal retraction. Eighty patients undergoing cardiac surgery were assigned to either Group 1 (AAS) or Group 2 (HU). Perioperative neurologic evaluations of the brachial plexus were performed and somatosensory evoked potentials (SSEPs) were collected during internal mammary artery harvest using asymmetric sternal retraction. Demographic data, SSEP changes, and postoperative brachial plexus symptoms were compared between groups. SSEP amplitude decreased in 95% of all patients during retractor placement with substantial decreases (>50%) observed on the left side in 50% of the AAS and 35% of the HU patients. Amplitude recovery was normally seen in both groups after asymmetric retractor removal. Similar changes were noted, to a lesser degree, on the right side. During asymmetric sternal retraction, HU positioning offered minimal benefit in reducing brachial plexus stress as measured by SSEP. Three of the seven AAS patients who reported brachial plexus symptoms had an ulnar nerve distribution of injury. However, none of the four patients with plexus symptoms in the HU group had ulnar nerve problems, suggesting that the higher incidence of postoperative symptoms observed with AAS positioning may occur from ulnar nerve compression. (Anesth Analg 1997;84:260-5)

Internal mammary artery revascularization in the patient on long-term renal dialysis

Twenty-six patients on long-term renal dialysis underwent coronary artery bypass grafting. The patients were divided into two groups: group 1, (16 patients) saphenous vein bypass grafts, and group 2, (10 patients) internal mammary artery in combination with saphenous vein bypass grafts. Both groups were similar in terms of cardiac hemodynamics and previous number of myocardial infarctions, though more group 1 patients were in New York Heart Association class III or IV. Patients in group 1 received 2.9 bypass grafts per patient; patients in group 2 received 4.0 bypass grafts per patient (4 with bilateral mammary arteries). No wound healing problems occurred in either group. Blood replacement was similar for both groups (group 1, 5.5 units/patient; group 2, 5.3 units/patient). More platelets were given to group 1 patients (16.2 units/patient) than group 2 patients (3.1 units/patient). We conclude that use of the internal mammary artery in patients on long-term renal dialysis does not alter wound healing or increase blood loss in this subset of patients.