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Biomedical subjects

C G Tribble

Publications and source records attributed to C G Tribble.

At least 19 recordsLinked to original sources
PubMed1999

Does a focal neurologic deficit contraindicate operation in a patient with endocarditis?

BACKGROUND: As many as 40% of patients with left-sided bacterial endocarditis will sustain a neurologic insult. The importance of a neurologic change as an indication or a contraindication for valve replacement remains controversial. METHODS: We performed a retrospective analysis of the records of 33 patients admitted to the University of Virginia Health Sciences Center between January 1, 1978, and June 30, 1996, with a diagnosis of endocarditis and a neurologic change. RESULTS: All 33 patients had echocardiographic or pathologic evidence of left-sided endocarditis; 23 were seen with focal neurologic findings and had a mortality rate of 22% (5 of 23), and 10 patients were seen with nonfocal, diffuse encephalopathy and had a mortality rate of 60% (6 of 10) (p<0.05). Of the 33 patients, 14 underwent operation and 19 were treated medically. The mortality rate was 21.4% (3 of 14) in the surgical group and 42.1% (8 of 19) in the medical group (p = not significant). In 71% (10 of 14) of the surgical patients, the operation was done within 1 week of the neurologic event. Additional neurologic deterioration occurred in 18.2% (2 of 11) of survivors in the surgical group and 9.1% (1 of 11) in the medical group (p = not significant). CONCLUSIONS: Choosing therapy for a patient with endocarditis and a neurologic change remains a difficult challenge. Initial findings of nonfocal, global dysfunction on examination are a predictor of a poor outcome. By comparing surgical and medical groups derived from the same series of patients, it is clear that patients with bacterial endocarditis and central nervous system changes face substantial mortality regardless of intervention. However, these data demonstrate that when compared with a similar group of medical patients, surgical patients who require and receive operation early in the course of their illness do comparatively well. Improving outcomes by delaying surgical intervention may serve to "select out" hardier patients but will lead to the death of patients who might benefit from such intervention.

Adult↗
PubMed1999

Membranous tracheobronchial injury repaired with gastric serosal patch.

This unusual case involves pharyngolaryngoesophagectomy complicated by injury to the membranous trachea and right bronchus. Repair was possible after partial sternal split and elevation of the tracheostoma through the anterior mediastinum, pulling the stomach to the neck, and using the stomach as a patch to repair the injury to the membranous portion of the airway.

Bronchi↗
PubMed1999

Reduced neutrophil infiltration protects against lung reperfusion injury after transplantation.

BACKGROUND: There is evidence that lung ischemia reperfusion injury is a result of the activation of components of the inflammatory cascade. However, the role of neutrophils in lung reperfusion injury continues to be a source of controversy. METHODS: Using an isolated, whole blood-perfused, ventilated rabbit lung model, we sought to characterize the pattern of reperfusion injury and investigate the contribution of neutrophils to this injury. Donor rabbits underwent lung harvest after pulmonary arterial prostaglandin E1 injection and Euro-Collins preservation solution flush. Group I lungs (n = 8) were immediately reperfused without ischemic storage. Group II lungs (n = 8) were stored for 18 h at 4 degrees C before reperfusion. Group III lungs (n = 10) underwent 18 h of ischemic storage and were reperfused with whole blood that was first passed through a leukocyte-depleting filter. All lungs were reperfused for 2 h. RESULTS: Arterial oxygenation in group III progressively improved, and was significantly higher than that of group II after 2 h of reperfusion (272.58+/-58.97 vs 53.58+/-5.34 mm Hg, p = 0.01). Both pulmonary artery pressure and pulmonary vascular resistance were significantly reduced in group III when compared with group II (27.85+/-1.45 vs 44.15+/-4.77 mm Hg, p = 0.002; and 30,867+/-2,323 vs 52,775+/-6,386 dynes x sec x cm(-5), p = 0.003, respectively). Microvascular permeability in group III lungs was reduced to 73.98+/-6.15 compared with 117.16+/-12.78 ng Evans blue dye/g tissue in group II (p = 0.005). Group III myeloperoxidase activity was 56.92+/-6.31 deltaOD/g/min compared with 102.84+/-10.41 delta0d/g/min in group II (p = 0.002). CONCLUSIONS: Leukocyte depletion of the blood reperfusate protects against microvascular permeability and significantly improves pulmonary graft function. The neutrophil plays a major role in amplifying lung injury later during reperfusion, and this lung ischemia reperfusion injury may be reversed through the interruption of the inflammatory cascade and the interference with neutrophil infiltration.

Animals↗
PubMed1999

Spinal cord protection during aortic cross-clamping using retrograde venous perfusion.

BACKGROUND: Paraplegia remains a devastating complication following thoracic aortic operation. We hypothesized that retrograde perfusion of the spinal cord with a hypothermic, adenosine-enhanced solution would provide protection during periods of ischemia due to temporary aortic occlusion. METHODS: In a rabbit model, a 45-minute period of spinal cord ischemia was produced by clamping the abdominal aorta and vena cava just below the left renal vessels and at their bifurcations. Four groups (n = 8/group) were studied: control, warm saline, cold saline, and cold saline with adenosine infusion. In the experimental groups, saline or saline plus adenosine was infused into the isolated cavae throughout the ischemic period. Clamps were removed and the animals to recovered for 24 hours before blinded neurological evaluation. RESULTS: Tarlov scores (0 = paraplegia, 1 = slight movement, 2 = sits with assistance, 3 = sits alone, 4 = weak hop, 5 = normal hop) were (mean +/- standard error of the mean): control, 0.50 +/- 0.50; warm saline, 1.63 +/- 0.56; cold saline, 3.38 +/- 0.26; and cold saline plus adenosine, 4.25 +/- 0.16 (analysis of variance for all four groups, p < 0.00001). Post-hoc contrast analysis showed that cold saline plus adenosine was superior to the other three groups (p < 0.0001). CONCLUSION: Retrograde venous perfusion of the spinal cord with hypothermic saline and adenosine provides functional protection against surgical ischemia and reperfusion.

Animals↗
PubMed1999

Preservation of intercostal arteries during thoracoabdominal aortic aneurysm surgery: a retrospective study.

OBJECTIVE: The purpose of this article was to examine the influence of reimplantation of patent intercostal and lumbar arteries on the incidence of postoperative paraplegia/paraparesis in patients undergoing clamp-and-sew surgical repair of thoracoabdominal aortic aneurysms. METHODS: Data from January 1987 through December 1997 were retrospectively collected on 132 patients. Ninety-one patients in group I underwent aneurysm repairs before January 1995 and did not undergo intercostal artery reimplantation. Group II included the more recent 41 patients who had vessels between the eighth thoracic intercostal and the second lumbar arteries reimplanted to the graft or preserved at the aortic anastomoses. RESULTS: The operative mortality rate was 13.2% (12/91) in group I and 4.9% (2/41) in group II (P =.22). The incidence of postoperative paraplegia was significantly lower in the more recent cohort of patients (8.8% [8/91] in group I vs 0% [0/41] in group II, P =.05). The overall rate of spinal cord dysfunction was lowered from 9.9% (9/91) in group I to 2.4% (1/41) in group II (P =.17). However, a multivariable logistic regression analysis identified only aneurysm extent (Crawford type I and type II) as a predictor of less postoperative spinal cord injury (P =.08). The average aortic crossclamp time in group I was 30.3 +/- 11.5 (SD) minutes, and the time of aortic occlusion in group II was not significantly prolonged, with an average crossclamp time of 31.0 +/- 21.0 (SD) minutes (P =. 88). CONCLUSIONS: An aggressive approach to maintain intercostal artery patency during clamp-and-sew repair of thoracoabdominal aortic aneurysms may effectively lower the incidence of spinal cord injury without prolonging aortic crossclamp time.

Aged↗
PubMed1999

Intern call schedules and their relationship to sleep, operating room participation, stress, and satisfaction.

BACKGROUND: The ideal resident call schedule remains unknown. This study assessed the impact of different call schedules on intern performance and education. METHODS: A year-long, prospective, observational study of first-year residents in a surgery training program was performed with use of intern sleep/operative logs and questionnaires, and faculty questionnaires. RESULTS: Compared with interns taking call every third or fourth night (and cross-covering a separate service), interns taking call every other night reported the greatest amount of fatigue and stress, the lowest satisfaction, and the fewest operative cases. Errors in patient care were not different between schedules. Multivariate analysis revealed that operative participation was inversely related to frequency of night call and level of fatigue post call, stress was related to fatigue while off call and service census, and overall satisfaction was associated with infrequency of call and operative cases performed. Faculty reported more errors by interns cross-covering other services and less operating room participation by interns taking call every other night. CONCLUSIONS: No single resident schedule optimally balances patient care and resident education and satisfaction. All 3 patterns of call studied are acceptable; specific decisions regarding the allocation of house staff manpower should be flexible and dependent on individual service and educational needs.

General Surgery↗
PubMed1998

Nitric oxide potentiates acute lung injury in an isolated rabbit lung model.

BACKGROUND: The effect of inhaled nitric oxide (NO) treatment on pulmonary function in the setting of adult respiratory distress syndrome is controversial. We examined the effect of inhaled NO on pulmonary function in an isolated rabbit lung model of oleic acid (OA)-induced acute lung injury. We hypothesized that NO would decrease pulmonary artery pressure and improve oxygenation. METHODS: Rabbit heart-lung blocks were isolated, flushed in vivo, harvested, and immediately perfused with whole blood and ventilated with 50% oxygen (O2). Pulmonary artery pressure was determined every 15 seconds for 60 minutes of perfusion. Oxygenation was determined by blood gas analysis of pulmonary venous effluent at 0, 20, 40, and 60 minutes after initiation of OA infusion. Rabbits were randomized into four study groups: saline control; OA control, which received a 20-minute infusion of 50% OA/ethanol solution; NO treatment (20 ppm NO inhaled before OA infusion); and NO control, which underwent NO (20 ppm) pretreatment, followed by saline infusion. Pulmonary artery pressure, oxygenation (arteriovenous O2 difference), compliance, and wet/dry lung weight were determined. RESULTS: Pretreatment with NO caused significant increases in pulmonary artery pressure (NO treatment versus NO control and saline control; no significant difference between NO treatment group and OA control group), and did not improve oxygenation in our model. CONCLUSIONS: Contrary to our hypothesis, pretreatment with NO potentiates acute lung injury in our isolated lung model. There was significant exacerbation of pulmonary hypertension and no improvement in oxygenation. Further investigation of the possible deleterious effects of NO in acute lung injury are needed, especially in the early acute phases of this process.

Animals↗
PubMed1998

Replacing the atherosclerotic ascending aorta is a high-risk procedure.

BACKGROUND: Improved techniques in cerebral and myocardial protection have made replacement of the chronically aneurysmal ascending thoracic aorta a safe and effective procedure. We hypothesized that patients with severe ascending or aortic arch atherosclerosis were at greater risk for operative complications during ascending aortic replacement because of the diffuse nature of their atherosclerotic process. METHODS: We retrospectively analyzed the records of 17 patients who received ascending aortic replacement during elective coronary artery bypass grafting (CABG) because of the intraoperative finding of severe atherosclerosis. All 17 patients underwent tube graft replacement of the ascending aorta under hypothermic circulatory arrest and retrograde cerebral perfusion before coronary artery bypass grafting. The outcomes for these patients were compared with those of a control group of 89 consecutive patients who underwent replacement for ascending thoracic aortic aneurysm. RESULTS: The hospital mortality rate for replacement of the ascending thoracic aorta for severe atherosclerosis was 23.5% (4/17) versus 2.25% (2 of 89) for the control group (p=0.006). The incidence of cerebrovascular accident in the atherosclerotic group was 17.6% (3/17) and 3.37% (3/89) for the control group (p=0.051). Nine of 17 atherosclerotic patients (52.9%) had operative morbidity. Only 20.2% (18 of 89) of the control patients had nonfatal postoperative complications. CONCLUSIONS: The severely atherosclerotic ascending aorta is a marker of diffuse atherosclerosis. Despite improved techniques of myocardial and cerebral protection, we have been unable to duplicate our success with ascending thoracic aneurysm repair. Preoperative screening of the ascending aorta by chest computed tomography may be appropriate in select high-risk patients to determine operability.

Aged↗
PubMed1998

Inhibition of inducible nitric oxide synthase after myocardial ischemia increases coronary flow.

BACKGROUND: The role of nitric oxide synthase in myocardial ischemia-reperfusion injury is complex. Our hypothesis was that inducible nitric oxide synthase has a role in the regulation of coronary flow after ischemia. METHODS: Four groups of isolated blood-perfused rabbit hearts underwent sequential periods of perfusion, ischemia, and reperfusion (20, 30, and 20 minutes). Two groups underwent 40 minutes of perfusion. Ischemic groups received saline vehicle, N omega-nitro-L-arginine methyl ester (L-NAME) or the highly specific inducible nitric oxide synthase inhibitor 1400W in low or high doses during reperfusion. Two nonischemic groups were treated with saline vehicle or 1400W during the last 20 minutes of perfusion. Left ventricular developed pressure and coronary flow were measured after each perfusion period. Ventricular levels of myeloperoxidase and cyclic guanosine monophosphate were measured at the end of the second perfusion period. RESULTS: Coronary flow was significantly increased in both 1400W groups versus L-NAME (p < 0.001) and in high-dose 1400W versus control (p < 0.001). Coronary flow was not significantly different between the nonischemic groups. Left ventricular developed pressure was not significantly different among the ischemic groups or between the two nonischemic groups. There were no differences in cyclic guanosine monophosphate levels in any of the ischemic hearts. Myeloperoxidase levels were significantly elevated in L-NAME versus high-dose 1400W, nonischemic 1400W, and nonischemic saline groups (p < 0.02). CONCLUSIONS: Highly selective inhibition of inducible nitric oxide synthase results in increased coronary flow after ischemia but not after continuous perfusion. This occurs with decreased neutrophil accumulation and a trend toward increased contractility without elevation of cyclic guanosine monophosphate levels.

Animals↗
PubMed1998

Simultaneous coronary artery bypass grafting and abdominal aneurysm repair decreases stay and costs.

BACKGROUND: Patients with large (> or = 5.0 cm) abdominal aortic aneurysms (AAA) frequently have marked associated coronary artery disease. We hypothesized that a single operation for coronary artery bypass grafting (CABG)/AAA would provide equivalent, if not improved, patient care while decreasing postoperative length of stay and hospital costs compared with staged procedures. METHODS: Eleven patients to date have undergone a combined procedure at our institution. Ten underwent CABG followed by AAA repair, whereas one patient received an aortic valve replacement before aneurysm repair. We performed a retrospective analysis comparing the postoperative length of stay and hospital costs for this single procedure to a combined cohort of 20 randomly selected patients who either received AAA repair (n = 10) or standard CABG (n = 10) during the same time period. RESULTS: No operative mortality has been reported. There were no episodes of neurologic deficit or cardiac complication after these procedures. The postoperative length of stay was significantly decreased for the CABG/AAA group compared with the combined postoperative length of stay for the AAA plus CABG group (7.44+/-0.88 days versus 14.10+/-2.00; p = 0.012). Total hospital costs were also significantly decreased for the CABG/AAA group compared with total hospital costs for the AAA plus CABG group ($22,941+/-$1,933 versus $34,076+/-$2,534; p = 0.003). CONCLUSIONS: A single operation for coronary revascularization and AAA repair is safe and effective. Simultaneous CABG and AAA repair substantially decreases postoperative length of stay and hospital costs while avoiding possible interim aneurysm rupture and repeat anesthesia.

Aged↗
PubMed1998

Preservation with 8-bromo-cyclic GMP improves pulmonary function after prolonged ischemia.

BACKGROUND: Cyclic guanosine monophosphate (cGMP) is a potent second messenger for the nitric oxide pathway in the pulmonary vasculature. Increased cytosolic cGMP levels elicit pulmonary vasodilatation resulting in decreased pulmonary vascular resistance and maximized pulmonary function after ischemia-reperfusion injury. We hypothesized that the addition of a membrane-permeable cGMP analogue (8-bromo-cGMP) to a Euro-Collins (EC) preservation solution would ameliorate pulmonary reperfusion injury better than prostaglandin E1 injection alone after prolonged hypothermic ischemia. METHODS: All lungs from New Zealand White rabbits (weight, 3 to 3.5 kg) were harvested en bloc, flushed with EC solution, and reperfused with whole blood for 30 minutes. Group 1 lungs (immediate control) were immediately reperfused. Group 2 lungs (control) were stored inflated at 4 degrees C for 18 hours before reperfusion. Groups 3 and 4 lungs were flushed with EC solution containing 200 micromol/L 8-bromo-cGMP and stored at 4 degrees C for 18 and 30 hours, respectively. Fresh, nonrecirculated venous blood was used to determine single-pass pulmonary venous-arterial oxygen gradients at 10-minute intervals. Assays for cGMP, cyclic adenosine monophosphate, nitric oxide synthase activity, and myeloperoxidase were performed on all lung tissue samples. Wet to dry weight ratios were determined after 2 weeks of passive desiccation. RESULTS: Oxygenation (venous-arterial oxygen gradient), pulmonary artery pressure, pulmonary vascular resistance, and edema formation were significantly improved in groups 3 and 4 (addition of 8-bromo-cGMP to EC plus 18 or 30 hours of hypothermic ischemia). Hypothermic storage (groups 2, 3, and 4) decreased both nitric oxide synthase activity and myeloperoxidase levels compared with immediate reperfusion (group 1). CONCLUSIONS: These results suggest that the addition of a membrane-permeable cGMP analogue to an EC pulmonary flush solution improves pulmonary function after prolonged storage compared with EC and prostaglandin (E1) preservation alone. The finding of myeloperoxidase reduced levels after hypothermic storage and subsequent reperfusion may suggest a more important role for pulmonary hemodynamic control in mitigating pulmonary reperfusion injury.

Alprostadil↗
PubMed1998

Hypothermic circulatory arrest does not increase the risk of ascending thoracic aortic aneurysm resection.

OBJECTIVE: The purpose of this study was to investigate the safety and efficacy of a period of deep hypothermic circulatory arrest (DHCA) during elective replacement of the ascending thoracic aorta. SUMMARY BACKGROUND DATA: DHCA has been implemented in ascending thoracic aortic aneurysm resection whenever the anatomy or pathology of the aorta or arch vessels prevents safe or adequate cross-clamping. Profound hypothermia and retrograde cerebral perfusion have been shown to be neurologically protective during ascending aortic replacement under circulatory arrest. METHODS: The authors conducted a retrospective analysis of 91 consecutive patients who underwent repair of chronic ascending thoracic aortic aneurysms from 1986 to present. The authors hypothesized that patients undergoing DHCA with or without retrograde cerebral perfusion during aneurysm repair were at no greater operative risk than patients who received aneurysm resection while on standard cardiopulmonary bypass. RESULTS: There were no significant differences in hospital mortality, stroke rate, or operative morbidity between patients repaired on DHCA when compared to those repaired on cardiopulmonary bypass. CONCLUSIONS: DHCA with or without retrograde cerebral perfusion does not result in increased morbidity or mortality during the resection of ascending thoracic aortic aneurysms. In fact, this technique may prevent damage to the arch vessels in select cases and avoid the possible complications associated with cross-clamping a friable or atherosclerotic aorta.

Aged↗
PubMed1998

Protective roles of nitric oxide and testosterone in endotoxemia: evidence from NOS-2-deficient mice.

Lipopolysaccharide (LPS)-induced septic shock, which triggers nitric oxide (NO) overproduction, multiple organ dysfunction, and death, can be affected by gender and sex hormones. We hypothesized that NO is beneficial during endotoxemia and that this beneficial effect is influenced by sex hormones. C57BL/6 wild-type (WT) mice and congenic inducible NO synthase knockout (KO) mice were injected with LPS, and mortality was recorded for 4 days. After 5 mg/kg LPS, female KO mice had significantly higher mortality than WT. After 12.5 mg/kg LPS, both male and female KO mice had significantly higher mortality than WT. Ovariectomy did not alter mortality, but orchiectomy dramatically increased mortality in KO mice. After 5 mg/kg LPS, exogenous testosterone completely prevented the increased mortality in KO female and orchiectomized KO male mice. WT survival was not affected by exogenous testosterone. After 12.5 mg/kg LPS, exogenous testosterone significantly improved survival of female KO mice. Serum enzymes and organ edema, which may not correlate with mortality, were significantly and similarly increased in both WT and KO endotoxemic mice; however, edema was not observed in KO hearts. Thus, NO plays a protective role in endotoxemia while having differential effects on different organs. Importantly, testosterone is beneficial in endotoxemia when NO production is deficient, and may be therapeutic in certain septic patients.

Animals↗
PubMed1997

Intraoperative hetastarch infusion impairs hemostasis after cardiac operations.

BACKGROUND: An outbreak of excessive bleeding after cardiac operations occurred at our institution when 5% albumin was in short supply and hetastarch became the preferred intraoperative colloid. As hetastarch may impair coagulation, we investigated the effects of its intraoperative administration on post-cardiac surgical hemostasis. METHODS: Indices of postoperative hemostasis were analyzed in 189 consecutive patients undergoing coronary artery bypass grafting. Three groups were compared: one group (n = 68) received a mean of 796 mL of hetastarch only in the operating room (a few minutes after cessation of cardiopulmonary bypass), another group (n = 59) received a mean of 856 mL postoperatively only, and a third group (n = 62) received no hetastarch. RESULTS: Compared with the other two groups, those patients administered hetastarch intraoperatively exhibited significant reductions in hematocrit and platelet count, a significant prolongation in the prothrombin time, and significant increases in both blood loss and hemostatic drug requirement. Also identified were obvious trends toward a greater transfusion requirement and reexploration rate for bleeding in the latter group. CONCLUSIONS: Hetastarch infusion just after weaning from cardiopulmonary bypass produces a clinically important impairment in post-cardiac surgical hemostasis. Intraoperative use of this agent during heart operations should be avoided until the safe timing of its administration is clarified.

Blood Loss, Surgical↗
PubMed1997

Intravenous phenylephrine preconditioning of cardiac grafts from non-heart-beating donors.

BACKGROUND: Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non-heartbeating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning. METHODS: Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non-heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 microg/kg (n = 7) before initiation of apnea. Non-heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia. RESULTS: Phenylephrine 25 microg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 +/- 0.5 versus 7.7 +/- 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 +/- 5.3 versus 41.0 +/- 3.4 mm Hg; p = 0.04). Phenylephrine 25 microg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09). CONCLUSIONS: Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.

Analysis of Variance↗