Effects of amino acids on substrate selection, anaplerosis, and left ventricular function in the ischemic reperfused rat heart.

The effect of aspartate and glutamate on myocardial function during reperfusion is controversial. A beneficial effect has been attributed to altered delivery of carbon into the citric acid cycle via substrate oxidation or by stimulation of anaplerosis, but these hypotheses have not been directly tested. 13C isotopomer analysis is well suited to the study of myocardial metabolism, particularly where isotopic and metabolic steady state cannot be established. This technique was used to evaluate the effects of aspartate and glutamate (amino acids, AA) on anaplerosis and substrate selection in the isolated rat heart after 25 min of ischemia followed by 30 or 45 min of reperfusion. Five groups of hearts (n = 8) provided with a mixture of [1,2-13C]acetate, [3-13C]lactate, and unlabeled glucose were studied: control, control plus AA, ischemia followed by 30 min of reperfusion, ischemia plus AA followed by 30 min of reperfusion, and ischemia followed by 45 min of reperfusion. The contribution of lactate to acetyl-CoA was decreased in postischemic myocardium (with a significant increase in acetate), and anaplerosis was stimulated. Metabolism of 13C-labeled aspartate or glutamate could not be detected, however, and there was no effect of AA on functional recovery, substrate selection, or anaplerosis. Thus, in contrast to earlier reports, aspartate and glutamate have no effect on either functional recovery from ischemia or on metabolic pathways feeding the citric acid cycle.

Aprotinin but not epsilon-aminocaproic acid decreases interleukin-10 after cardiac surgery with extracorporeal circulation: randomized, double-blind, placebo-controlled study in patients receiving aprotinin and epsilon-aminocaproic acid.

BACKGROUND: Extracorporeal circulation induces a systemic inflammatory response, which may adversely affect organ function. One manifestation of this response is increased fibrinolysis. Antifibrinolytic drugs such as aprotinin and epsilon-aminocaproic acid have been effective in reducing fibrinolysis and blood loss after extracorporeal circulation; however, the effects of antifibrinolytic drugs on proinflammatory and anti-inflammatory mediators are not known. This study examined the effects of aprotinin and epsilon-aminocaproic acid on plasma levels of proinflammatory [interleukin-6 (IL-6)] and anti-inflammatory [interleukin-10 (IL-10)] cytokines during and after extracorporeal circulation. METHODS AND RESULTS: Seventy-two patients undergoing coronary artery bypass grafting with extracorporeal circulation were randomly assigned in a double-blind study to receive high-dose aprotinin, epsilon-aminocaproic acid, or saline placebo. Plasma levels of IL-6 and IL-10 were measured at 5 time points before, during, and after extracorporeal circulation. In all 3 groups, both IL-6 and IL-10 rose significantly after institution of extracorporeal circulation and remained elevated through the first postoperative day. Compared with saline, aprotinin significantly reduced IL-10 (P=0.02) and peak IL-6 (P=0.02) after extracorporeal circulation. In contrast, none of the reductions in IL-6 and IL-10 by epsilon-aminocaproic acid achieved statistical significance. Both aprotinin and epsilon-aminocaproic acid decreased blood loss compared with saline, but there was no significant difference in the number of patients receiving blood products among the treatment groups. CONCLUSIONS: These data suggest that aprotinin and epsilon-aminocaproic acid differ in their effects on the inflammatory response to extracorporeal circulation. Aprotinin but not epsilon-aminocaproic acid appears to attenuate the rise in the proinflammatory and anti-inflammatory cytokines IL-6 and IL-10. Further studies will be required to determine if these cytokine alterations translate to changes in clinical outcomes.

Assessment of aortic regurgitation by transesophageal color Doppler imaging of the vena contracta: validation against an intraoperative aortic flow probe.

OBJECTIVES: This study was performed to validate the accuracy of color flow vena contracta (VC) measurements of aortic regurgitation (AR) severity by comparing them to simultaneous intraoperative flow probe measurements of regurgitant fraction (RgF) and regurgitant volume (RgV). BACKGROUND: Color Doppler imaging of the vena contracta has emerged as a simple and reliable measure of the severity of valvular regurgitation. This study evaluated the accuracy of VC imaging of AR by transesophageal echocardiography (TEE). METHODS: A transit-time flow probe was placed on the ascending aorta during cardiac surgery in 24 patients with AR. The flow probe was used to measure RgF and RgV simultaneously during VC imaging by TEE. Flow probe and VC imaging were interpreted separately and in blinded fashion. RESULTS: A good correlation was found between VC width and RgF (r = 0.85) and RgV (r = 0.79). All six patients with VC width >6 mm had a RgF >0.50. All 18 patients with VC width <5 mm had a RgF <0.50. Vena contracta area also correlated well with both RgF (r = 0.81) and RgV (r = 0.84). All six patients with VC area >7.5 mm2 had a RgF >0.50, and all 18 patients with a VC area <7.5 mm2 had a RgF <0.50. In a subset of nine patients who underwent afterload manipulation to increase diastolic blood pressure, RgV increased significantly (34 +/- 26 ml to 41 +/- 27 ml, p = 0.042) while VC width remained unchanged (5.4 +/- 2.8 mm to 5.4 +/- 2.8 mm, p = 0.41). CONCLUSIONS: Vena contracta imaging by TEE color flow mapping is an accurate marker of AR severity. Vena contracta width and VC area correlate well with RgF and RgV obtained by intraoperative flow probe. Vena contracta width appears to be less afterload-dependent than RgV.

Effect of biphasic endocardial countershock on pacing thresholds in humans.

The use of non-thoracotomy endocardial implantable defibrillators with pacing capabilities has increased substantially over the past 2 years. This report demonstrates that the pacing threshold increases in some patients after endocardial defibrillation, and substantiates the practice of using maximal pacing output after endocardial defibrillation.

Effects of repeated electrical defibrillations on cardiac troponin I levels.

Multiple endocardial countershocks applied during intraoperative endocardial implantable cardioverter-defibrillator testing for the purpose of defibrillation threshold determination resulted in detectable myocardial injury in 5 of 12 patients, as indicated by elevations in cardiac troponin I levels. This injury was not associated with acute changes on the surface electrocardiogram.

Results of extracorporeal membrane oxygenation in neonates with sepsis. The Extracorporeal Life Support Organization experience.

Use of extracorporeal membrane oxygenation for treatment of respiratory failure caused by sepsis is controversial because of concerns over survival benefit and hemorrhage-related complications. To evaluate the impact of the primary diagnosis of sepsis on outcome, we reviewed data from 6853 neonates in the Extracorporeal Life Support Organization Registry and defined two groups: group 1 (n = 1060), all patients undergoing extracorporeal membrane oxygenation with a primary diagnosis of sepsis; group 2 (n = 5793), those with any other primary diagnosis. A multivariate logistic regression analysis that considered 15 variables present before extracorporeal membrane oxygenation (including age, sex, birth weight, prior cardiopulmonary arrest, arterial blood gas results, and ventilator settings) was used to compare outcomes between groups. Survival was not different between the two groups (77%, group 1; 82%, group 2; p = 0.2480), although lung recovery was less frequent in the patients with sepsis (p = 0.0185). Group 1 had a higher incidence of complications including seizures (odds ratio 1.446, p = 0.0346), cerebral infarct or hemorrhage (2.310, p = 0.0001), need for dialysis (1.478, p = 0.0131), hypernatremia (2.089, p = 0.0019), hyperbilirubinemia (2.423, p = 0.0001), and dobutamine use (1.918, p = 0.0001). Neonates with sepsis are more likely to have neurologic, renal, and metabolic complications from extracorporeal membrane oxygenation but may still achieve a survival benefit equivalent to those without sepsis. From these data, extracorporeal membrane oxygenation should not be withheld from neonates solely on the basis of sepsis. Rather, management strategies should focus on limiting the incidence or severity of the common complications.

Nucleoside trapping during reperfusion prevents ventricular dysfunction, "stunning," in absence of adenosine. Possible separation between ischemic and reperfusion injury.

A previous study has shown that endogenous adenosine trapping during ischemia (by blocking adenine nucleoside transport and inhibiting adenosine breakdown) prevents myocardial stunning. In this study, we tested the hypothesis that delay of administration of inhibitors until reperfusion would similarly prevent myocardial stunning in the absence of entrapped adenosine. In both studies, a selective nucleoside transport blocker, p-nitrobenzyl-thioinosine, was used in combination with a potent adenosine deaminase inhibitor, erythro-9-(2-hydroxy-3-nonyl)adenine, to entrap adenosine (preischemic treatment) or inosine (postischemic treatment) in an in vivo canine model of reversible global ischemia. Twenty-five anesthetized adult dogs were instrumented (by sonomicrometry) to monitor left ventricular performance from the relationship between stroke work and end-diastolic length as a sensitive and load-independent index of contractility. Hearts of animals supported by cardiopulmonary bypass were subjected to 30 minutes of normothermic global ischemia and 60 minutes of reperfusion. Saline solution containing the pharmacologic agents were infused into the bypass circuit before ischemia (group 1) or during reperfusion (group 2). Control group (group 3) received saline before and after ischemia. Myocardial biopsy specimens were obtained before, during, and after ischemia, and levels of adenine nucleotides, nucleosides, oxypurines, and the oxidized form of nicotinamide-adenine dinucleotide were determined. Left ventricular contractility fully recovered within 30 minutes of reperfusion in the groups treated with erythro-9-(2-hydroxy-3-nonyl)adenine and p-nitrobenzyl-thioinosine (p < 0.05 versus control group). Myocardial adenosine triphosphate was depleted by 50% in all groups at the end of ischemia. Adenosine triphosphate recovered during reperfusion only in the group that was treated with inhibitors before ischemia (group 1). At the end of ischemia, adenosine levels were low (< 10% of total nucleosides) in the control group (group 3) and in the group treated only after ischemia (group 2). A high level of adenosine (> 90% of total nucleosides) was present in group 1. We infer that selective pharmacologic blockade of nucleoside transport, only after ischemic injury, accelerated functional recovery during reperfusion, even without trapping of endogenous adenosine during ischemia and without adenosine triphosphate recovery during reperfusion. Recovery of myocardial adenosine triphosphate required preischemic treatment and adenosine entrapment during ischemia and reperfusion. Therefore, nucleoside trapping may be used to prevent reperfusion-mediated injury after reversible ischemic injury.

Effects of glutamate and aspartate on myocardial substrate oxidation during potassium arrest.

OBJECTIVES: A recent report (J Clin Invest 1993;92:831-9) found no effect of glutamate plus aspartate on metabolic pathways in the heart, but the experimental conditions did not model clinical cardioplegia. The purpose of this study was to determine the effects of glutamate and aspartate on metabolic pathways feeding the citric acid cycle during cardioplegic arrest in the presence of physiologic substrates. METHODS: Isolated rat hearts were supplied with fatty acids, lactate, pyruvate, glucose, and acetoacetate in physiologic concentrations. These substrates were enriched with 13C, which allowed a complete analysis of substrate oxidation by 13C-nuclear magnetic resonance spectroscopy in one experiment. Three groups of hearts were studied: arrest with potassium cardioplegic solution, arrest with cardioplegic solution supplemented with glutamate and aspartate (both in concentrations of 13 mmol/L), and a control group without cardioplegic arrest. RESULTS: In potassium-arrested hearts, the contributions of fatty acids and lactate to acetyl coenzyme A were reduced, and acetoacetate was the preferred substrate for oxidation in the citric acid cycle. The addition of aspartate and glutamate in the presence of cardioplegic arrest did not further alter patterns of substrate utilization substantially, although acetoacetate use was somewhat lower than with simple cardioplegic arrest. When [U-13C]glutamate (13 mmol/L) and [U-13C]aspartate (13 mmol/L) were supplied as the only compounds labeled with 13C, little enrichment in citric acid cycle intermediates could be detected. CONCLUSIONS: Glutamate and aspartate when added to potassium cardioplegic solutions have relatively minor effects on citric acid cycle metabolism.

Myocardial protective effects of the class Ic antiarrhythmic agent flecainide.

The class Ic antiarrhythmic agent flecainide has recently become available in this country for management of ventricular arrhythmias. The pharmacologic and electrophysiologic features of this class of drug--marked sodium channel blockade producing inhibition of phase 0 of the myocardial action potential, moderate blockade of slow inward (calcium) channels, and general lack of systemic toxicity--suggest that these agents may exert significant myocardial protective effects. This hypothesis was tested in isolated, perfused rat hearts subjected to 30 minutes of global normothermic ischemia followed by 30 minutes of reperfusion after pretreatment with (1) Krebs-Henseleit buffer (n = 7); (2) Krebs-Henseleit buffer with potassium adjusted to 20.9 mmol/L with potassium chloride (n = 10); and (3) Krebs-Henseleit buffer plus flecainide acetate 50 mg/L (0.12 mmol/L) (n = 11). Severity of ischemic injury was assessed by time to ischemic contracture: 9.9 +/- 1.3 (Krebs-Henseleit buffer), 18.4 +/- 1.1 (potassium chloride), and 25.4 +/- 1.0 (flecainide) minutes (mean +/- standard error of the mean) (p less than 0.05 among all groups). Functional recovery after ischemia and reperfusion was measured by developed pressure (expressed as percent of preischemic control): 19.6 +/- 5.4 (Krebs-Henseleit buffer), 70.8 +/- 3.2 (potassium chloride), and 67.3 +/- 2.7 (flecainide). These results suggest that class Ic agents afford significant myocardial protection from global normothermic ischemia.

Triple-drug immunosuppression with steroid discontinuation by six months after heart transplantation.

BACKGROUND: Triple-drug immunosuppression with cyclosporine, azathioprine, and prednisone is associated with complications which might be reduced by steroid withdrawal. METHODS: In two groups of heart transplant recipients maintained on an identical regimen of cyclosporine and azathioprine, prednisone was withdrawn in group I patients (n = 35) by 6 months after transplantation, whereas in group II patients (n = 49) prednisone was never discontinued. RESULTS: Survival was similar in the two groups. The incidence of acute graft rejection was significantly higher in group I (54%) than in group II (12%), whereas infective complications were significantly lower in group I than in group II (0.63 versus 1.02 episode/patient). The degree of posttransplantation weight gain, lipid abnormalities, and incidence of hypertension were not modified by the fast tapering of prednisone, whereas the incidence of cataract and compression fracture and the degree of bone loss were significantly reduced in group I. Graft function and incidence of coronary artery disease were similar in the two groups. CONCLUSIONS: The present data suggest that prednisone can be safely withdrawn in heart transplant recipients without jeopardizing survival and graft function. Longer follow-up is needed to assess the full impact of early withdrawal of steroids from triple-drug immunosuppression, especially on long-term graft function and incidence of coronary artery disease. Benefits of early steroid withdrawal included a reduction in bone loss, which might ultimately have a major positive impact on the extent of long-term rehabilitation and exercise tolerance after heart transplantation.

Results of extracorporeal membrane oxygenation in children with sepsis. The Extracorporeal Life Support Organization.

BACKGROUND: Despite good results in neonates, extracorporeal membrane oxygenation (ECMO) is less well accepted in pediatric patients. Older children frequently undergo ECMO for severe bacterial, viral, or aspiration pneumonia and many have coexisting systemic sepsis. We reviewed data from a national registry to study the influence of sepsis on survival from ECMO. METHODS: Six hundred fifty-five patients (aged 2 weeks to 17 years) with respiratory failure treated with ECMO were divided into two groups by the presence (n = 76) or absence (n = 579) of sepsis. Groups were compared by univariate analysis and by multivariate logistic regression that considered 10 additional pre-ECMO variables (age, sex, weight, arterial blood gas results, ventilator parameters, and renal failure). RESULTS: By univariate analysis, survival was lower in septic children (36.8% versus 51.6%; p < 0.02). However, by multivariate analysis, sepsis was not an independent survival predictor (odds ratio, 0.578; 95% confidence interval, 0.288-1.162; p = 0.12). The ECMO complications predicted by the presence of sepsis included (1) seizures, (2) other neurologic complications, and (3) infection at other sites (all p < 0.05). CONCLUSIONS: Systemic sepsis does not independently influence survival in pediatric ECMO. This therapy should not be withheld solely because of sepsis, although neurologic complications may occur more frequently.

Neonatal extracorporeal membrane oxygenation complicated by sepsis. Extracorporeal Life Support Organization.

The onset of sepsis in neonates while on extracorporeal membrane oxygenation (ECMO) may portend adverse results. Nevertheless, ECMO has been used as a therapy in the management of septic conditions. This study assessed morbidity and mortality in neonates in whom septic complications developed while they were on ECMO. Of 5,123 neonates in the Extracorporeal Life Support Organization Registry undergoing ECMO for nonseptic indications, 217 patients had development of septic complications. A multivariate logistic regression analysis that considered 15 pre-ECMO criteria was performed to evaluate outcome. Mortality was higher in the septic group (35% versus 17%; p < 0.002) and ECMO duration averaged 85 hours longer (p < 0.001). Septic neonates had a greater frequency of complications including seizures, gastrointestinal bleeding, renal dysfunction, and metabolic problems (all p < 0.05). Transfusion requirements were doubled. Oxygenator thrombi and hemofilter malfunction occurred more often in septic patients (p < 0.03). New strategies to prevent sepsis and associated thrombotic and metabolic complications may be indicated. A critical reappraisal of continued aggressive support may be warranted when septic complications develop in neonates during ECMO.

Neonatal myocardial oxygen consumption during ventricular fibrillation, hypothermia, and potassium arrest.

BACKGROUND: Many investigators have examined oxygen consumption in adult heats under conditions that simulate those encountered during cardiac operations and those that approximate basal metabolism. Few studies, however, have addressed this issue in neonatal myocardium. METHODS: Hearts from 3- to 9-day-old piglets were studied in a blood-perfused isolated heart preparation in working, empty beating, fibrillating, potassium chloride-arrested (at 37 degree C and 15 degree C), and hypothermic (15 degree C) states. RESULTS: Oxygen consumption (expressed in milliliters of O2 per 100 g of ventricular tissue per minute; mean +/- standard deviation) was 6.69 +/- 1.91 for working hearts and fell to 3.19 +/- 1.08 for empty-beating hearts, 3.72 +/- 0.84 for fibrillating hearts, 1.30 +/- 0.34 for potassium-arrested hearts at 37 degree C, 0.37 +/- 0.18 for hypothermic (15 degree C) hearts, and 0.32 +/- 0.10 for potassium-arrested hearts at 15 degree C. All values were significantly different except the two obtained at 15 degree C. CONCLUSIONS: Vented fibrillating hearts used more oxygen than empty beating hearts. The addition of an arresting concentration of KCl did not lower oxygen consumption below that observed with hypothermia alone at 15 degree C. If potassium-based cardioplegia is incrementally beneficial in neonatal myocardial protection over that afforded by hypothermia alone, its effects cannot be explained by reduction in oxygen demand.

Early evacuation of traumatic retained hemothoraces using thoracoscopy: a prospective, randomized trial.

BACKGROUND: Failure to adequately evacuate blood from the pleural space after trauma may result in extended hospitalization and complications such as empyema. METHODS: Patients with retained hemothoraces were prospectively randomized to either a second tube thoracostomy (group 1, n = 24) or video-assisted thoracoscopy (VATS) (group 2, n = 15). Group 1 patients in whom additional tube drainage failed were subsequently randomized to either VATS or thoracotomy. Study end points included duration and costs of hospitalization. RESULTS: During a 4-year period, 39 patients were entered into the study. Patients in group 2 had shorter duration of tube drainage (2.53 +/- 1.36 versus 4.50 +/- 2.83 days, mean +/- standard deviation; p < 0.02), shorter hospital stay after the procedure (3.60 +/- 1.64 versus 7.21 +/- 5.30 days; p < 0.02), and shorter total hospital stay (5.40 +/- 2.16 versus 8.13 +/- 4.62 days; p < 0.02). Hospital costs were also less in this group ($7,689 +/- 3,278 versus $13,273 +/- 8,158; p < 0.02). There was no mortality in either group. No group 2 patient required conversion to thoracotomy. In 10 group 1 patients additional tube placement failed, and this subset was randomized to VATS (n = 5) or thoracotomy (n = 5). No significant difference in clinical outcome was found between these subgroups. CONCLUSIONS: In many patients treated only with additional tube drainage (group 1), this therapy fails, necessitating further intervention. Intent to treat with early VATS for retained hemothoraces decreases the duration of tube drainage, the length of hospital stay, and hospital cost. Early intervention with VATS may be a more efficient and economical strategy for managing retained hemothoraces after trauma.

Importance of complete system removal of infected cardioverter-defibrillators.

We describe a case of device infection after implantable cardioverter-defibrillator implantation managed by removal of all hardware except a portion of the epicardial sensing electrodes. Recurrent septic complications developed until all residual foreign material was eliminated. Despite anecdotal reports of successful management without device removal, extraction of all hardware components should be considered standard treatment for this complication.

Successful surgical repair of aortic dissection presenting with complete heart block.

Acute dissection of the ascending aorta can present with complete heart block if the dissecting hematoma involves the interatrial septum near the atrioventricular node. We report a case of acute type A dissection presenting with complete heart block treated with emergency grafting of the ascending aorta, aortic valve replacement, and coronary artery bypass grafting. The patient survived, although complete heart block persisted requiring permanent pacemaker implantation.

Histologic evidence of the safety of endoscopic saphenous vein graft preparation.

BACKGROUND: Endoscopic methods of saphenous vein procurement have recently been introduced. These techniques have been successful in limiting pain and wound complications, but less information on assessing potential trauma to the harvested vein segment is available. METHODS: Fourteen male patients undergoing coronary artery bypass grafting were included in the study. Nine patients underwent endoscopic procurement of saphenous vein whereas 5 patients underwent procurement using standard open techniques. Histologic appearance and immunohistochemical studies (factor VIII:vWF [von Willebrand factor protein] and CD34) of the vein segments were reviewed in a blinded fashion. RESULTS: On histologic analysis, no differences in the intima, media, or adventitia were found between endoscopically and conventionally obtained vein segments. Immunohistochemical staining for factor VIII:vWF and CD34 showed no differences between veins harvested by the two techniques. CONCLUSIONS: Endoscopic saphenous vein harvesting does not appear to traumatize the vessel wall any more than open techniques. Longitudinal assessment is necessary to evaluate long-term patency in vein grafts procured using this method.

Esophageal Doppler monitor determinations of cardiac output and preload during cardiac operations.

BACKGROUND: Perioperative management of cardiac surgical patients frequently mandates measurements of cardiac output and left ventricular filling. This study compared cardiac output and left ventricular filling measured by pulmonary artery (PA) catheter and esophageal Doppler monitor (EDM). METHODS: Thirty-four patients undergoing coronary artery bypass grafting were prepared by implanting a PA catheter, an EDM, and a transit-time ultrasonic flow probe around the ascending aorta. In 20 patients, left ventricular end-diastolic short-axis area (EDA) was measured by transesophageal echocardiography. At five time points, cardiac output was measured from the flow probe, the EDM, and the PA catheter (by thermodilution), and left ventricular filling was assessed from the PA catheter (as PA diastolic pressure), the EDM (corrected flow time), and the EDA. For cardiac output, concordance correlations relating EDM to flow probe and PA catheter to flow probe were calculated, transformed (Fisher's z transformation), and compared by Student's t test. For left ventricular filling, regression coefficients were created between corrected flow time and EDA and between PA diastolic pressure and EDA. Spearman correlations were compared by Wilcoxon rank sum test. RESULTS: The EDM and the PA catheter exhibited similar relationships to the flow probe (concordance correlations, 0.55 +/- 0.35 [mean +/- standard deviation] and 0.49 +/- 0.34, respectively; p = 0.088). The correlation between corrected flow time and EDA was better than the correlation between PA diastolic pressure and EDA (concordance correlations, 0.49 +/- 0.55 versus 0.10 +/- 0.43, respectively; p < 0.01). CONCLUSIONS: These data suggest that the EDM may offer a less invasive technique for evaluating cardiac output and a more accurate estimate for preload compared with the PA catheter.

Effects of storage and reperfusion oxygen content on substrate metabolism in the isolated rat lung.

BACKGROUND: Lung transplantation requires a period of storage and ischemia; we examined the largely unknown effects of that period on intermediary metabolism. METHODS: Two groups of isolated rat lung blocks (n = 16 each) were flushed with Euro-Collins solution and harvested. The lung blocks were immediately ventilated and either perfused for 30 minutes with an erythrocyte-based solution containing carbon 13 labeled substrates (group 1) or stored for 6 hours at 1 degree C and then reperfused (group 2). Half of each group was reperfused at a physiologic Po2 the other half at high Po2. Analysis of carbon 13 isotopomers was performed to determine substrate utilization through aerobic pathways in lung tissue. RESULTS: Lungs from both groups oxidized all major substrates. The contribution of fatty acids to acetylcoenzyme acid oxidized in the citric acid cycle was significantly higher in group 2 than in group 1 (31.3% +/- 2.2% versus 22.0% +/- 2.1%, p < 0.05). Perfusate Po2 did not affect substrate preference. Gas exchange was worse in stored lungs. CONCLUSIONS: After a period of hypothermic ischemia and storage, substrate preference in lung tissue exhibits a switch towards fatty acids. As fatty acid oxidation occurring after ischemia is deleterious in other organs, strategies to inhibit this process in stored lungs may warrant further investigation.

Indications for using video-assisted thoracoscopic surgery to diagnose diaphragmatic injuries after penetrating chest trauma.

BACKGROUND: Video-assisted thoracoscopic surgery (VATS) has been shown to be an accurate method for identifying diaphragmatic injuries (DIs). The purpose of this investigation was to establish specific indications for the use of VATS after penetrating chest trauma. METHODS: A retrospective review of all patients undergoing VATS after penetrating chest trauma at a level 1 trauma center over an 8-year period was performed. Logistic regression was used in an attempt to identify independent predictors of DI. RESULTS: One hundred seventy-one patients underwent VATS assessment of a hemidiaphragm, and 60 patients (35%) were found to have a DI. Five independent risk factors for DI were identified from analyzing the patient records: abnormal chest radiograph, associated intraabdominal injuries, high-velocity mechanism of injury, entrance wound inferior to the nipple line or scapula, and right-sided entrance wound. CONCLUSIONS: In the largest published series of patients undergoing VATS to exclude a DI, this review identifies five independent predictors of DI after penetrating chest trauma. A diagnostic algorithm incorporating these five factors was designed with the goal of reducing the number of unrecognized DIs after penetrating chest trauma by using VATS for patients at greatest risk for such injuries.