Systemic venous collateral development after the bidirectional cavopulmonary anastomosis. Prevalence and predictors

OBJECTIVES: To determine the prevalence of systemic venous collaterals after the bidirectional cavopulmonary anastomosis and the factors associated with their development. BACKGROUND: Systemic venous collaterals have been found after cavopulmonary anastomosis. Methods. Cardiac catheterization was performed in 103 patients before and after a bidirectional cavopulmonary anastomosis. RESULTS: After surgery, 51 venous collaterals were identified in 32 patients (31%). Collateral development was associated with an abnormal superior vena caval connection (56% incidence vs. 26% with a single right superior vena cava, p = 0.01) and postoperative factors including pulmonary artery distortion (53% incidence vs. 22% without distortion, p = 0.002); increased superior vena caval mean pressure (14 +/- 5 mm Hg versus 11 +/- 4 mm Hg with no collaterals, p = 0.0002); increased pulmonary artery mean pressure (13 +/- 4 mm Hg vs. 11 +/- 4 mm Hg with no collaterals, p = 0.02); lower right atrial mean pressure (5 +/- 2 mm Hg vs. 6 +/- 3 mm Hg with no collaterals, p = 0.04); and increased mean gradient between superior vena cava and right atrium (8 +/- 3 mm Hg vs. 5 +/- 4 mm Hg with no collaterals, p = 0.0002). Using multiple logistic regression, only this last factor was independently associated with collateral development with an odds ratio per 1 mm Hg of 1.33 (95% CI 1.12-1.58, p = 0.001) for their presence. CONCLUSIONS: Systemic venous collaterals occur frequently after a bidirectional cavopulmonary anastomosis and are found postoperatively when a significant pressure gradient occurs between cava and right atrium.     

The predictive value of intraoperative somatosensory evoked potential monitoring: review of 244 procedures

INTRODUCTION: There is some controversy regarding the value of intraoperative neurophysiological monitoring in predicting postoperative neurological deficits. We discuss our experience with the use of intraoperative somatosensory evoked potentials (SSEPs) during surgery of cranial base tumors. METHODS: We retrospectively reviewed all of the procedures that had been performed for the resection of cranial base tumors from July 29, 1993, through March 16, 1995. One hundred ninety-three consecutive patients had undergone a total of 244 procedures. SSEP waveforms were classified as follows: Type I, no change; Type II, change that reverts to baseline; Type III, change that does not revert to baseline; and Type IV, complete flattening of the SSEP waveform without improvement. Two patients had no waveforms from the beginning of the case (Type V) and were excluded from further analysis. New immediate postoperative neurological deficits were recorded. RESULTS: There were 64 male and 129 female patients, with a mean age of 46.6 years. One hundred seventy-seven patients had Type I SSEP waveforms, 13 of whom had postoperative deficits (7%). Fifty-six patients had Type II SSEPs, and nine (16%) of them had postoperative neurological deficits. Six patients had Type III SSEPs, and three had Type IV SSEPs, all of whom (100%) had postoperative deficits. There was a correlation between SSEP type and the results of the postoperative neurological examinations. The positive predictive value is 100%, and the negative predictive value is 90%. Although a change in the waveform that did not revert to baseline (Types III and IV) always predicted a postoperative deficit, a normal waveform did not always rule out postoperative deficits. Pathological abnormality, vessel encasement, vessel narrowing, degree of cavernous sinus involvement, brain stem edema, middle fossa location, final amount of resection, age, and tumor size correlated with a high predictive value of SSEP monitoring on univariate analysis (P < 0.05). None of these variables correlated significantly on multivariate analysis (P > 0.05), although brain stem edema was close (P = 0.0571). CONCLUSION: Intraoperative SSEPs have a high positive predictive value during surgery for cranial base tumors, but they do not detect all postoperative deficits.     

The prevalence of foot ulceration and its correlates in type 2 diabetic patients: a population-based study

The prevalence of peripheral neuropathy, peripheral vascular disease, and foot ulceration in Type 2 diabetic patients in the community were determined in a community-based study. Eight hundred and eleven subjects (404 male, 407 female, mean age 65.4 (range 34-90) years, diabetes duration 7.4 (0-50) years) from 37 general practices in three UK cities were studied. Neuropathy was diagnosed clinically using modified neuropathy disability scores which were ascertained using structured interviews and clinical examinations by one observer in each city. Peripheral vascular disease was diagnosed if a history of revascularization was present or > or = 2 foot pulses were absent. History of current or previous foot ulceration was recorded. The prevalence of neuropathy was 41.6% (95% confidence limits 38.3-44.9%) and the prevalence of PVD, 11% (9.1-13.7%). Forty-eight percent of neuropathic patients reported significant neuropathic symptoms. Forty-three patients (5.3% (3.8-6.8%)) had current or past foot ulcers; 20 of these were pure neuropathic ulcers, 13 neuroischaemic, 5 pure vascular, and 5 were unclassified. Multiple logistic regression showed history of amputation, neuropathy disability score, and peripheral vascular disease to be significantly associated with foot ulceration after adjusting for age and diabetes duration. A substantial proportion of Type 2 diabetic patients, often elderly patients who do not attend hospitals, suffered from peripheral neuropathy and peripheral vascular disease. These patients are at risk of foot ulceration and may benefit from preventive footcare.     

Effect of hypertonic saline solution and dextran on ventricular blood flow and heart-lung interaction after hemorrhagic shock

BACKGROUND: Hypertonic saline solutions may have beneficial hemodynamic effects in the resuscitation of hemorrhagic shock. The effects on cardiac function and potential interaction with lung function are controversial and served as the basis for this study. METHODS: Domestic swine were resuscitated from hemorrhagic shock with equivalent sodium loads of lactated Ringer's solution (LR) or 7.5% NaCl plus 10% dextran (HSD). Hemodynamic data were obtained at baseline, shock, and after resuscitation. Right ventricular ejection fraction and left ventricular change in pressure with respect to time (dP/dt) were used to index contractility. Regional myocardial blood flow was determined with microspheres. Lung water was determined gravimetrically. RESULTS: There were no differences in the ability to restore hemodynamic parameters with equivalent sodium loads of LR and HSD resuscitation. Right ventricular ejection fraction and left ventricular change in pressure with respect to time were only transiently affected by shock and resuscitation. Regional myocardial blood flow was increased above baseline values after HSD. The total resuscitation volumes were 1958 +/- 750 mL and 140 +/- 31 mL with LR and HSD, respectively. CONCLUSIONS: Although LR and HSD were equally effective in the early resuscitation of hemorrhagic shock, this occurred at the expense of significantly greater volume requirements for resuscitation with LR. This may contribute to cardiac dysfunction in this setting. Enhanced regional myocardial blood flow after HSD resuscitation may be beneficial against ongoing myocardial stress.     

Prolonged pregnancy. Labor induction versus intensified monitoring]

This study was made in order to evaluate the effect of a policy of induction of labour at 42 weeks of gestation in post-term pregnancies. A group of 139 women with uncomplicated post-term pregnancies, who gave birth at the maternity ward at Herlev Hospital in 1993 was compared to a group of 145 women, who gave birth in 1996 at the same location. In 1993 spontaneous labour was awaited with twice weekly surveillance tests, and labour was only induced if there was evidence of foetal or maternal compromise, while in 1996 labour was induced at 42 weeks of gestation. There were at 20.1% inductions of labour in 1993 compared to 44.8% in 1996. The perinatal morbidity and birth complication rates were similar in the two groups.     

Effect of hypotension preceding death on the function of lungs from donors with nonbeating hearts

BACKGROUND: A shortage of suitable brain-dead donors continues to severely limit lung transplantation. Use of donors with nonbeating hearts has been suggested as a solution. Lungs are unique, in that aerobic metabolism can continue in the absence of blood circulation because oxygen is present in airways and alveoli. Animal studies have shown reasonable cadaveric graft function up to several hours after sudden death by drug administration. However, hemodynamic instability before death may worsen lung function through activation and pulmonary sequestration of neutrophils and release of inflammatory mediators. Because many potential cadaveric donors experience hypotension before death, this study was undertaken to assess the effect of hypotensive shock on cadaveric lung viability. METHODS: A rat isolated lung reperfusion model was used to assess pulmonary function over 3 hours of reperfusion or until gross pulmonary edema developed. Twenty-five rats were randomly allocated to the following study groups, which were based on status before lung harvest: (1) control: no interventions; (2) hypotensive: 1 hour of hypotension by exsanguination to a mean blood pressure of 30 to 40 mm Hg; (3) cadaver: death by cervical dislocation followed by 3 hours of in situ lung ischemia; (4) hypotensive + 3 hours cadaver: 1 hour of hemorrhagic shock, followed by death and 3 hours of in situ ischemia; (5) hypotensive + 2 hours cadaver: similar to group 4, except the in situ ischemia was abbreviated to 2 hours. RESULTS: No significant differences were found among group 1, 2, or 3 lungs with regard to wet to dry weight ratios, gas exchange, and pulmonary arterial or airway pressures. However, all group 4 lungs became grossly hemorrhagic and developed severe pulmonary edema within 10 minutes of reperfusion. Group 5 lungs fared only marginally better, with two of five lungs tolerating 3 hours of reperfusion. CONCLUSIONS: A period of hypotension before death severely impairs cadaveric lung viability.