OBJECTIVE:Hypercoagulability may compromise the patency of bypass grafts. The authors hypothesized that perioperative in vitro platelet responses to varying agonists (eg, thrombin, platelet activating factor, collagen, adenosine diphosphate) correlate with early graft thrombosis after off-pump coronary artery bypass grafting (OPCAB).DESIGN AND PARTICIPANTS:Prospective study of 78 OPCAB patients with 151 venous bypass grafts treated with perioperative aspirin and intraoperative heparin (250 U/kg).SETTING:Tertiary, academic medical center.INTERVENTIONS:None.MEASUREMENTS AND MAIN RESULTS:Hypercoagulability, defined by TEG (maximum amplitude [MA]>70 mm), whole-blood aggregometry (>15 ohms after 5 mcl/mL collagen) or hemoSTATUS (Ch5CR>0.5), was serially assessed around OPCAB. An immediate decline in platelet function after surgery and on postoperative day 1 returned to normal by postoperative day 3 in most patients. Graft blood flow was analyzed intraoperatively, and vein biopsies were analyzed for endothelial disruption. Graft patency was assessed by multichannel computed tomography coronary angiography on postoperative day 5. No differences in any of the platelet function assays were noted for the 8 patients with graft thrombosis (n=8 grafts) versus the 68 patients with all patent grafts (n=129 grafts). Ten patients developed a rise in platelet function postoperatively >1 SD above baseline; only 1 developed graft thrombosis (p=not significant v patients with normal platelet function).CONCLUSIONS:OPCAB is not associated with a significant activation in postoperative platelet function. This study suggests that if hypercoagulability exists after OPCAB, it is not involved in the pathogenesis of arterial thrombotic events such as early bypass graft failure.

Background. Visual loss from optic neuropathy rarely occurs in the perioperative period in patients who have undergone nonocular surgery. We performed a retrospective, matched, case-control study to determine the incidence of perioperative optic neuropathy (PON) after cardiac surgery with the use of cardiopulmonary bypass (CPB) and to determine risk factors that may lead to this potentially devastating complication.Methods. Medical records of all patients undergoing cardiac surgery during a 9-year period were reviewed retrospectively to identify visual loss from acute unilateral and bilateral optic neuropathy during the perioperative period that had developed in patients. Data were collected from these patients and compared with data from control subjects matched for age, gender, risk factors for vascular disease, and type of surgery to determine the incidence of and potential risk factors for PON.Results. Of 9701 surgical patients requiring CPB, 11 patients (0.113%) with PON were identified. Although both the absolute and relative drop in hemoglobin during the perioperative period approached statistical significance, no other putative risk factors were identified.Conclusions. The risk of PON associated with cardiac surgery in which CPB is used is low but substantial. The factors that lead to the condition remain unknown, although the presence of systemic vascular disease and both the absolute and relative drop in hemoglobin during the perioperative period seem to be important. Because PON often causes profound permanent visual loss, we recommend that patients, particularly those with systemic vascular disease, for whom cardiac surgery with CPB is planned, be made aware of this potential complication. (C) 2004 by The Society of Thoracic Surgeons.

From the Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD. Reprints: Timothy B. Gilbert, MD Department of Anesthesiology University of Maryland, South Hospital Room S11-C10, 22 S. Greene Street, Baltimore, MD 21201-1595 (e-mail: [email protected]).

DIFFERENTIAL LUNG VENTILATION and novel methods for ventilation are used occasionally to manage significant bronchopleural fistulae (BPF), in hopes of reducing air loss and enhancing its closure. A patient in whom adequate oxygenation and ventilation could only be achieved using airway pressure release ventilation (APRV) independently to the nonoperative lung unaffected by BPF is described.

J Thorac Cardiovasc Surg 2003;125:1157-8

BACKGROUND If surgeons could "see " through blood and cardiac chamber walls, it would ultimately be unnecessary to open the heart or use cardiopulmonary bypass to perform procedures such as atrial septal defect (ASD) closure or mitral valve repair. Conventional echocardiography generates cross-sectional images that are not satisfactory as the only visualization for surgical procedures, and current 3-Dimensional (3-D) CT and echo systems take several minutes to compose and process a single still frame. Recently, however, the first system for real-time 3-D echocardiography has been developed. This study examines whether real-time 3-D echocardiography can provide images of sufficient anatomic definition, depth perception, and image resolution to substitute for optical visualization in performing ASD closures. METHODS A prototype Volumetrics 3-D echocardiographic system was evaluated in a water bath on a complex-surfaced standard reference model to determine the image resolution and define the ideal imaging parameters. A static image and views of sutures being placed with an endoscopic needle driver and two commercial suture placement devices were evaluated at multiple angles and distances from the target. The resulting images were graded by a blinded reviewer. Once the best imaging parameters were determined, five porcine ASDs were closed with interrupted sutures, running sutures, or a pursestring suture using only echo visualization. RESULTS The highest quality images were obtained with the probe at a distance of 4-6 cm and at angles perpendicular or 45 degrees forward to the target. Spatial and temporal resolutions were adequate to suture all ASDs closed under only echo guidance. CONCLUSIONS The evaluated real-time 3-D echo system provided adequate spatial and temporal information to act as a guide for surgical procedures.

OBJECTIVE:To study the effects of electrical applications and subsequent postshock hypotension on myocardial performance and vascular tone during implantable cardioverter-defibrillator (ICD) placement. DESIGN:Prospective, blinded, observational investigation. SETTING:Single, university-affiliated institution. PARTICIPANTS:Twenty patients undergoing elective ICD placement and testing under general anesthesia. INTERVENTIONS:None. MEASUREMENTS AND MAIN RESULTS:Serial measurements were made of hemodynamic variables, left ventricular end-systolic (ESA) and end-diastolic (EDA) areas, fractional-area-of-contraction (FAC), time of hypoperfusion (when mean arterial pressure < or =50 mmHg postshock), and applied conversion energy. Multiple linear regression was performed to determine correlations among collected variables, and repeated measures analysis of variance was used to compare mean values. Minimal changes were detected in mean values of arterial, pulmonary, and central venous pressures; cardiac output; heart rate; and mixed venous saturation during repeated testing. Percentage changes in cardiac index (CI) rose and systemic vascular resistance index (SVRI) fell, however, as the number of shocks increased, reaching significance at the seventh and eighth shocks (v baseline; both p = 0.015). The percentage change in CI was linearly related to hypoperfusion time and accumulated energy (%deltaCI = 1.553 + [0.068 x sigma hypoperfusion time [sec]], r = 0.92, p < 0.001; %deltaCI = 0.326 + [0.125 x sigma Energy [J]], r = 0.94, p < 0.001). The percentage change in SVRI was inversely related to hypoperfusion time and accumulated energy (%deltaSVRI = 2.195 - [0.122 x sigma energy [J]], r = 0.79, p = 0.004; %deltaSVRI = 0.542 - [0.0634 - sigma hypoperfusion time [sec]], r = 0.73, p = 0.01). Echocardiographic EDA, ESA, and FAC were not significantly changed but showed substantial variability. CONCLUSION:Hemodynamic stability was generally well maintained during ICD placement and testing. Increases in CI were associated with concurrent reductions in systemic afterload, rather than enhanced FAC. Increasing postshock hypotension and applied energy were associated with decreases in CI and systemic afterload. Insignificant, but highly variable, changes were noted echocardiographically.

Background: If surgeons could see through blood and cardiac chamber walls, it would ultimately be unnecessary to open the heart or use cardiopulmonary bypass to perform procedures such as atrial septal defect (ASD) closure or mitral valve repair. Conventional echocardiography generates cross-sectional images that are not satisfactory as the only visualization for surgical procedures, and current 3-Dimensional (3-D) CT and echo systems take several minutes to compose and process a single still frame. Recently, however, the first system for real-time 3-D echocardiography has been developed. This study examines whether real-time 3-D echocardiography can provide images of sufficient anatomic definition, depth perception, and image resolution to substitute for optical visualization in performing ASD closures.Methods: A prototype Volumetrics 3-D echocardiographic system was evaluated in a water bath on a complex-surfaced standard reference model to determine the image resolution and de ne the ideal imaging parameters. A static image and views of sutures being placed with an endoscopic needle driver and two commercial suture placement devices were evaluated at multiple angles and distances from the target. The resulting images were graded by a blinded reviewer. Once the best imaging parameters were determined, five porcine ASDs were closed with interrupted sutures, running sutures, or a pursestring suture using only echo visualization.Results: The highest quality images were obtained with the probe at a distance of 4-6 cm and at angles perpendicular or 45 degrees forward to the target. Spatial and temporal resolutions were adequate to suture all ASDs closed under only echo guidance.Conclusions: The evaluated real-time 3-D echo system provided adequate spatial and temporal information to act as a guide for surgical procedures.

IMPLICATIONS:An overdose of the antiarrhythmic drug, lidocaine hydrochloride, was inadvertently administered to a patient through an arterial pressure monitoring apparatus, resulting in cardiac asystole. This medication error demonstrates to all anesthesia care team members the importance of preventing similar occurrences.

Background: Cross-clamping of the descending aorta during operative repairs causes sudden, significant reductions in renal function that may persist well beyond arterial clamp release. Commonly used agents, such as dopamine and mannitol, have not consistently affected renal outcome in these high-risk patients. Fenoldopam mesylate is a novel, highly selective dopamine type-I agonist that preferentially dilates the renal and splanchnic vasculature, but has not been investigated in patients undergoing prolonged aortic clamping for whom adverse renal outcomes should be more likely. Methods and Results: Twenty-two adult patients without significant pre-existing renal dysfunction and presenting for elective repairs of abdominal aortic aneurysms were studied. Fenoldopain mesylate was infused after obtaining baseline values ranging from 0.1 to 1.0 pg/kg/min for the first 24 hours postoperatively to maintain mean arterial pressure ±25% baseline. Serial renal function indices, including creatinine clearance and electrolyte fractional excretions, were measured at baseline, at aortic clamping and unclamping, and post-clamp release, and were estimated through hospital discharge. Creatinine clearance fell during abdominal exploration and clamping, reaching a nadir with clamp removal. Partial recovery occurred by 2 hours after clamp removal, and returned to baseline values by postoperative day 1 and thereafter. Fractional excretions rose rapidly throughout the operative phase. Total fenoldopam dose was directly related to the baseline creatinine clearance; after clamp removal, creatinine clearance was directly related to the mean arterial pressure at the lowest dose of fenoldopam, and inversely related to the mean arterial pressure at clamp release. Conclusions: In elderly patients with severe vascular disease undergoing aneurysmal repairs, the use of a fenoldopam infusion in this open-label, uncontrolled trial was associated with a relatively rapid return of renal function to baseline values, despite profound decreases during aortic cross-clamping. Further studies will be necessary to investigate how fenoldopam infusions compare with traditional therapies.

Pulmonary artery thromboendarterectomy (PTE) is a potentially curative surgical procedure for chronic thromboembolic pulmonary hypertension. It is, nevertheless, associated with considerable mortality caused by postoperative complications, such as reperfusion pulmonary edema (RPE) (i.e., pulmonary infiltrates in regions distal to vessels subjected to endarterectomy) and right heart failure (RHF). However, there are no reports about the influence of different postoperative treatment strategies on complications and mortality. Therefore, we compared two different treatment strategies. In Group I (n = 33), positive inotropic catecholamines and vasodilators were avoided during termination of cardiopulmonary bypass (CPB) and thereafter, and mechanical ventilation was performed with low tidal volumes < 8 mL/kg, duration of inspiration:duration of expiration = 3:1, and peak inspiratory pressures < 18 cm H2O. In Group II (n = 14), positive inotropic catecholamines and vasodilators were regularly used for termination of CPB and thereafter, and ventilation was performed with high tidal volumes (10–15 mL/kg) and peak inspiratory pressures up to 50 cm H2O. Hemodynamics, the incidence of RPE and RHF, duration of ventilation, morbidity, and mortality were recorded. Cardiac index was comparable before surgery (2.11 ± 0.09 vs 2.08 ± 0.09 L · min−1 · m−2) and 20 min after CPB (2.26 ± 0.09 vs 2.60 ± 0.20 L · min−1 · m−2). RPE occurred in 6.1% (Group I) versus 14.3% (Group II), and RHF was observed in 9.1% (Group I) versus 21.4% (Group II). Mortality was 9.1% (Group I) versus 21.4% (Group II). Thus, the avoidance of positive inotropic catecholamines and vasodilators in combination with nonaggressive mechanical ventilation after PTE was associated with a low incidence of RPE, RHF, duration of ventilation, and mortality after PTE. Implications The avoidance of positive inotropic catecholamines and vasodilators in combination with nonaggressive mechanical ventilation was associ- ated with a low incidence of reperfusion pulmonary edema and/or right heart failure after pulmonary artery thromboendarterectomy.

The Baltimore Hip Studies, a multicenter, noninterventional, observational trial, provided an opportunity to investigate the effects of anesthetic technique on the long-term outcome of elderly patients after hip fracture repair. Detailed interviews assessing functional status and pain were conducted during the hospital stay. Out-of-hospital evaluations were repeated after the procedure at 2, 6, 12, 18, and 24 months with a portable gait and balance laboratory. Multivariate analysis was done to determine the effects of anesthetic technique on functional and other outcomes, after controlling for multiple baseline variables. Of 741 enrolled patients who completed the study, 430 and 311 patients received spinal anesthesia or general anesthesia, respectively. Subgroup analysis of three spinal anesthetics, tetracaine, lidocaine, and epinephrine, was also done. In the present large observational study, general anesthesia was at least as efficacious as spinal anesthesia, and possibly better, in affording good long-term outcome.

Single-lung ventilation using a double-lumen endobronchial tube (EBT) is often performed for surgical procedures involving the thorax. The ability to isolate and collapse the nondependent lung is particularly imperative for thoracoscopic procedures, because adequate visualization of most intrathoracic structures depends on near complete atelectasis. Despite proper placement and use of an EBT, severe airway injury by the tube tip or either of its cuffs may occur occasionally. Previous reports seem to be limited to injury during open thoracotomy, in which broad visual exposure of the entire thorax is possible. We report a case of iatrogenic bronchial rupture during the use of an EBT for staging thoracoscopy in which the site of injury was not appreciated initially during the videoscopic examination. Case Report A 53-yr-old, previously healthy patient presented for right-sided thoracoscopic evaluation for staging of biopsyproven esophageal adenocarcinoma. Physical examination was unremarkable; height and weight were 160 cm and 68 kg, respectively. Following the uneventful induction of general anesthesia, a 37F, left-sided, styletted EBT (BronchoCath[registered sign]; Mallinckrodt, Glen Falls, NY) was passed easily through the vocal cords and into the left mainstem bronchus. We performed fiberoptic bronchoscopy (FOB) to confirm proper tube placement and to visualize inflation of the endobronchial balloon cuff; <3 mL of air was required to achieve an adequate seal. Appropriate lung isolation was then confirmed by auscultation. After turning the patient to a left-lateral decubitus position, thoracoscopy commenced with trochar insertion and carbon dioxide insufflation (peak pressure

Performance of a wind instrument requires appreciable lung volume and diaphragmatic mechanical force, skilled breath control, adequate patency and humidity of air passages, and precise coordination of the oropharyngeal cavity. Depending on the instrument class, variable rates of air flow, pressure, and duration are necessary to produce optimal tone quality. Wind players may be seriously impaired by respiratory diseases that, comparatively, might appear trivial to the nonperformer. The workplace environment should be assessed for occupational hazards when managing these patients, and smoking should be particularly discouraged. Controversy exists implicating wind instrument use in the exacerbation of respiratory disease, including bronchial, laryngeal, pharyngeal, and oral anatomic changes--a result of the constant barotrauma of performance. Asthma is the most common chronic pulmonary disorder among wind players, and therapeutic programs that include breath training and physical exercise improve symptoms, endurance, and general well-being.

STUDY OBJECTIVES To characterize acute changes in the dynamic, passive mechanical properties of the lungs and chest wall, elastance (E) and resistance (R), caused by lung volume reduction surgery (LVRS). DESIGN Prospective data collection. PATIENTS Nine anesthetized/paralyzed patients with severe emphysema. INTERVENTIONS Bilateral LVRS. MEASUREMENTS AND RESULTS From measurements of airway and esophageal pressures and flow during mechanical ventilation throughout the physiologic range of breathing frequency (f) and tidal volume (VT), E and R of the total respiratory system (Ers and Rrs), lungs (EL and RL), and chest wall (Ecw and Rcw) immediately before and after LVRS were calculated. After surgery, Ers, EL, Rrs, and RL were all greatly increased at each combination off and VT (p<0.05). Ecw and Rcw showed no consistent changes (p>0.05). The increases in EL were greatest in those patients with the lowest residual volumes, highest FEV1 values, and highest maximum voluntary ventilations measured 3 months preoperatively (p<0.05); the increases in RL were greatest in those patients with the lowest preoperative residual volumes (p<0.05). The largest increases in RL were in those patients with the largest decreases in residual volume and total lung capacity, measured 3 months postoperatively, caused by LVRS (p<0.05). CONCLUSION Acute effects of LVRS are large increases in lung elastic tension and resistance; these increases need to be considered in immediate postoperative care, and can be predicted roughly from results of preoperative pulmonary function tests.

To the Editor: In his review of Dermatology in Emergency Care (Feb. 12 issue),1 Dr. Greaves incorrectly uses the generic name ephedrine for a 2 percent phenylephrine spray used to treat a localized mucosal reaction. Phenylephrine hydrochloride is an α-adrenergic agonist that is useful for topical as well as intravenous vasoconstriction. It is commonly dispensed (in the United States, at least) as a 1 percent concentration. Ephedrine, a generic, indirect-acting sympathomimetic agent, is ubiquitous in perioperative care. It is dispensed in 5 percent ampules that are generally diluted before use. These drugs are therefore not equivalent.

With the growing reliance on the implantable cardioverter defibrillator (ICD) for the primary treatment of life-threatening ventricular arrhythmias, interactions between these devices and antiarrhythmic drugs has assumed increased clinical importance. The effects of antiarrhythmic drugs on defibrillation threshold (DFT) have been investigated [1]. Lidocaine, a commonly used antiarrhythmic drug, has generally been reported to increase DFT (requires more energy to defibrillate the heart) on a concentration-dependent basis in experimental animal preparations [2,3], but there are relatively little data available regarding the effects of lidocaine on DFT in humans. We describe a major increase in DFT that occurred in a patient who received 100 mg of intravenous (IV) lidocaine to attenuate the pain during the injection of an IV anesthetic during routine ICD implantation. Case Report A 59-yr-old man with coronary artery disease and moderately severe left ventricular dysfunction was referred for ICD implantation after electrophysiologic study revealed an easily inducible, rapid, sustained, monomorphic ventricular tachycardia. Implantation was performed with sedation provided by IV midazolam (7 mg), fentanyl (100 micro g), and droperidol (0.75 mg). The initial DFT was determined to be 15 joules using a stepdown approach from 20 joules with a transvenous lead system (Endotak C; Guidant Corp., Cardiac Pacemakers, St. Paul, MN) and a biphasic waveform. Brief general anesthesia was then induced with 200 mg of propofol administered IV with 100 mg of lidocaine. The pulse-generator pocket was constructed in the subcutaneous tissue superficial to the rectus sheath, and the lead was tunneled to the pocket and connected to the pulse generator. A total of 10 mL of 1% lidocaine was used for local infiltration during the procedure. During subsequent device testing, a 30-J biphasic shock was insufficient to defibrillate the patient in two consecutive trials, and a biphasic 34-J "rescue" shock was required to restore normal sinus rhythm. Subsequently, the implant team discovered that IV lidocaine had been administered. Serum lidocaine concentration, drawn 30 min after the 100-mg bolus of lidocaine, was 3.8 micro g/mL (therapeutic range 1.5-5.0 micro g/mL). After allowing an additional 30 min for the serum lidocaine concentration to dissipate, repeat testing revealed a biphasic DFT of 10 J. The patient has done well since that time and has been successfully defibrillated by his device on several occasions. Discussion The major finding in the present case report is that lidocaine, when administered IV for the purpose of preventing discomfort associated with the administration of IV propofol, can significantly increase DFT and have potentially important clinical consequences. Given the time course of the events (30-J shocks that failed twice and a subsequent DFT of 10 J after sufficient time had elapsed to allow the serum lidocaine concentration to decrease), we believe it unlikely that our findings are artifactual. In this case, the knowledge that lidocaine can increase DFT prevented unnecessary revision of the lead system. Like many other antiarrhythmic medications, lidocaine increases DFT, usually in a dose-related manner [2]. Echt et al. [4] obtained DFT in 16 patients before and after the administration of a 200 to 250-mg loading dose of lidocaine followed by a 3-mg/min maintenance infusion. They found that 7 of 8 patients with a serum lidocaine concentration increased >or=to5 micro g/mL had a significant increase in DFT. In contrast, DFT increased in only two patients with lower serum concentrations, although in those two patients, it increased to 25 and 30 J. The maximum output of most commercially available ICDs is 30-34 J. In our case, the blood sample was drawn 30 minutes after the lidocaine bolus had been administered, therefore, it is probable that the serum concentration was considerably higher at the time of the failed shocks. Assuming that lidocaine is eliminated by first-order kinetics with a half-life of 120 minutes, the estimated initial lidocaine concentration would be approximately 4.8 micro g/mL at the time of the failed shocks and 3.2 micro g/mL one hour later, when repeat DFT testing was successful. Propofol is an IV general anesthetic that has become increasingly popular recently because of rapid induction and emergence with few side effects [5]. One of the major drawbacks in the use of propofol is the pain associated with IV administration. Accordingly, it has become customary to administer propofol in conjunction with a local anesthetic, most often lidocaine [5,6]. Although the effects of propofol on DFT have not been fully elucidated, the lack of problems in direct current cardioversion in patients treated with propofol [7] suggests that it is unlikely to have played a role in our findings. Based upon our experience, it would be prudent to use IV lidocaine with caution in patients with ICDs. The dramatic increase in DFT encountered in our patient was most probably secondary to the large (1.4 mg/kg) dose of lidocaine administered and appears less likely with the use of smaller doses (0.1-0.2 mg/kg), which are still sufficient to minimize pain [5]. Alternatively, patients should be cautioned about the possibility of brief pain, and propofol should be administered through large-bore catheters using a free-flowing IV line. For patients known to have a low pain threshold, pentothal or metoclopramide, which have also been reported to attenuate the local discomfort of propofol injection, may be added to the infusion [8,9]. Our findings have another potentially important implication: lidocaine is recommended by the American Heart Association (Guidelines for Advanced Cardiac Life Support) for use in patients with persistent ventricular fibrillation [10]. Our experience and other published data [2-4] suggest that this recommendation should be reevaluated.