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Objective: Heparin-induced thrombocytopenia (HIT) is the most common form of drug-induced immune-mediated thrombocytopenia. HIT may be aggravated by life-threatening arterial and venous thrombosis and, to a lesser extent, hemorrhagic complications. We investigated the incidence of thromboembolic and hemorrhagic complications in critically ill patients with the multiple organ dysfunction syndrome and HIT., Design: Case-control study., Setting: A 33-bed general intensive care unit in a university-affiliated teaching hospital., Patients: Twenty consecutive patients with laboratory-proven HIT compared with 20 contemporary, consecutive patients without HIT., Interventions: Unfractionated heparin or low-molecular-weight heparin were replaced by danaparoid sodium in patients with HIT., Measurements and Results: Heparin-induced thrombocytopenia was proven by a positive platelet aggregation test. The HIT group consisted of 14 males and 6 females aged 65.2+/-10.8 years (mean +/- standard deviation) with APACHE II scores of 26.7+/-5.4. Thrombocytopenia less than 100 x 10(9)/l developed within 6.4+/-7.0 days. In 12 patients thrombocytopenia resolved after discontinuation of unfractionated heparin in 8.8+/-6.4 days. Arterial and venous thromboembolic complications occurred more frequently in HIT patients than in non-HIT patients (10/20 (50%) versus 0/20 (0%); chi-square p<0.001). Hemorrhagic complications also occurred more frequently in HIT patients than in non-HIT patients (17/20 (85%) versus 7/20 (35%); chi-square p=0.001)., Conclusion: In critically ill patients with HIT, the incidence of thromboembolic complications and hemorrhagic complications was remarkably high.

Objectives: In a randomized clinical trial of patients undergoing elective coronary artery bypass grafting, we evaluated the effect of intraoperative whole blood sequestration and autotransfusion on postoperative blood loss and the use of allogeneic blood products., Methods: Male patients were included if it was possible to obtain at least 500 mL of autologous blood. For patients in group H (heparin autotransfusion, 50 patients; mean age 59 +/- 8 years), an average of 670 +/- 160 mL heparinized blood was drawn before bypass and reinfused after the period of the extracorporeal circulation. For patients in group C (citrate autotransfusion, 48 patients; mean age 60 +/- 10 years), 450 +/- 109 mL of citrate blood, drawn before administration of heparin, was used. Controls (N-group) consisted of 46 patients aged 62 +/- 8 years. Strict transfusion criteria were used, and blood loss and use of allogeneic blood products during the hospital stays of all patients were recorded. Mean differences with their 95% confidence intervals adjusted for potential confounders were obtained by multiple linear regression., Results: The mean difference (95% confidence interval) of blood loss of group H minus N was -93 mL (-307 to 139) and for C minus N was -66 mL (-186 to 179). The mean number of allogeneic blood transfusions for group H was 0.85 +/- 1.74. Group C and group N used 0.94 +/- 1.56 and 0.84 +/- 1.24., Conclusion: In coronary artery bypass grafting there is no effect of heparin or citrate intraoperative whole blood sequestration with regard to blood loss or use of allogeneic blood.

Background: Early detection and quantification of brain damage in neonatal asphyxia is important. In adults, S100 protein in blood is associated with damage to the central nervous system., Objective: To determine whether S100 protein can be detected in arterial and venous cord blood of healthy newborns and to relate S100 protein concentrations in cord blood to mode of delivery., Method: S100 protein levels in umbilical cord blood of 81 healthy infants were determined., Results: S100 protein was present in arterial (median concentration 1.62 micro g/l) and venous (median concentration 1.36 micro g/l) cord blood. Levels were significantly higher in vaginal births (median arterial concentration 1.72 micro g/l; median venous concentration 1.48 micro g/l) than births by caesarean section (1.51 micro g/l and 1.26 micro g/l respectively)., Conclusion: More research is necessary to determine whether S100 protein is a useful marker in neonatal asphyxia.

Objective: To assess the optimal moment of central vascular catheter replacement balancing infectious and mechanical complications in continuous renal replacement therapies in critically ill patients with acute renal failure., Methods: Prospective sequential trial with historical controls to compare liberal catheter replacement when clinically indicated with routine catheter replacement every 5 days in consecutive patients treated by continuous arteriovenous hemodiafiltration in a level I secondary referral intensive care unit of a university-affiliated teaching hospital. Intention-to-treat analysis., Measurements and Main Results: Twenty-two patients underwent catheter replacement when clinically indicated (group II), and 21 patients served as historical controls (group I). The groups were comparable for sex, age, Acute Physiology and Chronic Health Evaluation II scores, comorbidity, and creatinin and urea levels at the start of continuous arteriovenous hemodiafiltration. In group I, 71 catheters were used for 346 treatment days, and in group II, 68 catheters were used for 495 treatment days. The mean duration of catheterization was 4.9 +/- 2.0 days vs. 7.3 +/- 4.5 days, respectively (Student's t-test p <.001). There was no significant difference between the incidence of colonization of catheters (46.8% in group I vs. 39.1% in group II; chi-square p =.35) In group I, bacteremia and catheter sepsis occurred in two patients, whereas this did not occur in group II. The occurrence of mechanical complications was comparable in both groups (15.5% in group I vs. 19.1% in group II). There were significantly more mechanical complications with arterial vs. venous catheters (17 vs. 7; chi-square p =.027)., Conclusion: When catheters were changed as clinically indicated, they remained significantly longer in situ vs. being replaced routinely every 5 days; infectious and mechanical complications were comparable. The incidence of catheter sepsis was low (2.2%), and no prosthesis infection occurred. Catheter replacement when clinically indicated seems to be as safe as routine replacement every 5 days.

Objectives: to investigate whether transcranial Doppler (TCD) monitoring can identify patients at risk of hyperperfusion, and whether active postoperative treatment of selected patients decreases the risk of intracerebral haemorrhage (ICH)., Design: a case cohort study of 688 patients undergoing carotid endarterectomy (CEA) with intraoperative TCD monitoring., Methods: sixty-two patients (9%) fulfilled the TCD criteria for hyperperfusion, i.e. >100% increase of peak blood flow velocity or pulsatility index of the middle cerebral artery, compared to preclamp baseline values. In these patients, blood pressure was closely monitored and controlled postoperatively., Results: postoperatively, seven of these patients (11%) exhibited clinical signs or symptoms of hyperperfusion but no cerebral haemorrhage (ICH). This is a significantly better outcome (p <0.005) compared to a 2% incidence of ICH after CEA in previous years in our hospital., Conclusions: patients at risk of hyperperfusion syndrome after CEA can be identified intraoperatively by TCD monitoring. In these selected patients, immediate and adequate postoperative treatment of hypertension results in a decreased risk of intracerebral haemorrhage., (Copyright 1999 Harcourt Publishers Ltd.)

Objective: To update mortality rates and long-term survival of patients admitted to the hospital with ruptured abdominal aortic aneurysm (AAA) and to study prognostic factors associated with mortality., Design: Retrospective follow-up., Materials: 309 patients (274 men, 35 women, average age 71) admitted to the hospital between January 1980 and January 1994 who were surgically treated for ruptured AAA were studied., Methods: To identify the preoperative (9), intraoperative (23) and postoperative (49) variables associated with mortality logistic regression analysis (mortality within 48 h) and Cox regression analysis (mortality between 48 h and 30 days) were performed., Results: Hospital mortality improved from 1980 to 1994. Compared with the normal population adjusted for age and sex the long-term mortality rate was increased (standardised mortality ratio 2.1; 95% confidence interval 1.7-2.5). Increased age, peroperative hypotension and need for a bifurcated graft were associated with significantly increased mortality. Co-morbidity was not a predictive variable. Overall hospital mortality was 25%., Conclusion: Surgical repair of ruptured AAA should be considered even in patients with co-morbidity. Elderly patients with severe preoperative hypotension have a very high mortality rate and surgery may not be justified in these cases. Long-term survival is also worse in older patients.

Objective: To determine the influence of cardio-pulmonary-bypass-time on hospital mortality and ICU-morbidity in isolated CABG surgery., Methods: Between 1985 and 1994 perioperative data of 8578 consecutive CABG operations were prospectively collected. Seven variables: gender, redo vs. primary operation, elective vs. urgent surgery, age in 4 categories, use of IMA, number of distal anastomoses (> 4 vs. < = 4), and cardio-pulmonary-bypass-time in four categories were entered in multivariate logistic regression analysis and odds ratios for respective cardio-pulmonary-bypass-time-categories with regard to mortality, length-of-stay in the ICU and 8 ICU-complications were calculated. Bypass-time up to 90 min was the reference category, the other categories were from 1.5 to 2.5 h, 2.5 to 3.5 h, and longer than 3.5 h., Results: 8337 operations had complete data. Mortality and ICU-morbidity were low. The odds ratios for mortality were 2.3 (P = 0.0094), 7.4 (P < 0.0001) and 20.7 (P < 0.0001) for ascending bypass-time-categories. The odds ratios for prolonged ICU-stay were 1.8 (P = 0.0002), 3.3 (P < 0.0001) and 7.9 (P < 0.0001) for ascending bypass-time-categories. For postoperative complications the same pattern was found: consequently higher odds ratios for longer bypass-time-categories., Conclusion: The highly significant correlation between cardio-pulmonary-bypass-time-category and the occurrence of undesirable postoperative events is demonstrated by the consequent rise in odds ratios. This independent influence of cardio-pulmonary-bypass-time on outcome reflects both problems encountered during revascularisation and time-related influence of cardio-pulmonary-bypass on the human body. When a predictive model was created, CPBT proved to be a good predictor of undesirable postoperative events.

We examined the incidence of delirium and cognitive disorders after cardiac operations and the related risk factors. The value of pre- and intraoperative QEEG was determined. Using the Mini-Mental State Examination and the Saskatoon Delirium Checklist, 321 patients were tested during the immediate postoperative period. Forty-four patients (14%) showed delirium, 68 (23%) cognitive disorders and 26 (9%) both. Significant risk factors for the development of cognitive disorders were age > or = 70 yr, female gender, duration of cardiopulmonary bypass > or = 2.5 h and aorta-cross-clamping > 70 min. Risk factors for delirium were age > or = 70 yr, female gender and Hb < 5 mmol 1(-1) intraoperatively. The preoperative QEEG showed significant differences between the groups with and without a cognitive disorder, while the intraoperative QEEG showed significant differences between the groups with and without delirium. Different risk factors for delirium and cognitive disorders are a possible explanation for the controversies in the literature, where neuropsychologic complications were grouped together. A low intraoperative Hb is an important risk factor for the development of delirium and can be treated. The preoperative QEEG may have prognostic significance in the occurrence of cognitive disorders, while the intraoperative QEEG may have prognostic significance in the occurrence of delirium.

Background: Selective decontamination of the digestive tract (SDD) with non-absorbable antibiotics was extensively used at intensive care units (ICU) in Europe to prevent nosocomial infections in critically ill patients. After three recent meta-analyses in which it was demonstrated that SDD did not influence hospital stay and mortality in these patients several ICU's decided to stop the routine use of SDD., Objective: To examine the effects of the cessation of SDD on nosocomial infections, mortality and hospital stay at an ICU in post-operative patients., Design: Retro- and prospective follow-up., Patients: Post-operative patients with mechanical ventilation (MV) for > or = 5 days at an ICU were included. The retrospective group (SDD group) comprised of 138 patients (mean age 66, range 10-91; 78% male) and the prospective group (non-SDD group) of 142 patients (mean age 67 range 18-85; 65% male). The SDD regime consisted of colistin, tobramycin and amphotericin B. Cessation of the SDD was accompanied by a shortening of the routine intravenous cefuroxime prophylaxis., Results: There was a nonsignificant increase from an average 21 to 23 days ICU stay in the non-SDD group when compared with the SDD group (p > 0.05). Of the 280 patients 97 (35%) died on the ICU. The risk of death was lower in the non-SDD group (adjusted hazard ratio 0.7 with 95% Cl 0.5-1.1). There was a trend towards an increase in infections as a cause of death in the non-SDD group (38% of the ceased patients versus 20% in the SDD group) (p > 0.05). The incidence of respiratory tract infection (per 1000 person days) was 80 (95% Cl 48-113) in the non-SDD group versus 19 (95% Cl 8-22) in the SDD group (adjusted hazard ratio 4.5 (95% Cl 2.9-7.1))., Conclusion: The cessation of the routine application of SDD in post-operative patients mechanically ventilated for 5 days or more did nod adversely affect survival nor increased length of stay at the ICU. There may have been a shift to infections as a cause of death after cessation of SDD.

Objectives: To investigate the effects of perioperative occlusion of intestinal arteries on clinical outcome and changes in sigmoidal intramuscular pH (pHi). To determine the value of sigmoidal pHi measurement in predicting ischaemic colitis after aortic reconstructive surgery., Design: Prospective, non-selective, open study., Materials: Forty patients undergoing elective aortic infrarenal surgery were monitored with pHi. Pre- and postoperative digital venous subtraction angiography was combined with operative data to evaluate perioperative occlusion of intestinal arteries., Results: All patients had a significant (p< 0.05) drop in pHi after aortic clamping which returned to baseline 2-4 h after declamping. None of the patients had clinical signs of ischaemic colitis postoperatively. All patients had angiographically proven, patent superior mesenteric arteries pre- and postoperatively. Patients were divided into three groups: patients with no changes in intestinal arteries (n=13), patients with perioperative occlusion of the inferior mesenteric artery (n=22) and patients with perioperative occlusion of the inferior mesenteric and one or both iliac arteries (n = 5); there were no significant differences in pHi values between the groups., Conclusions: Return of the sigmoidal pHi to baseline values within 6-12 h after declamping probably predicts a postoperative course without ischaemic colitis. Perioperative occlusion of the inferior mesenteric artery alone, or in combination with occlusion of one or both internal iliac arteries, does not cause ischaemic colitis in patients whose sigmoidal pHi rises after declamping.

Objective: To determine survival rates of patients treated for more than 30 days in an intensive care unit (ICU)., Design: Retrospective, descriptive., Setting: Intensive care unit of the St. Antonius Hospital in Nieuwegein, the Netherlands., Methods: All patients who required more than 30 consecutive days ICU treatment between January 1985 and January 1992 were included. With the aid of a computerised data base the medical records of all patients were analysed. If discharged, their family doctor was contacted for information about survival and quality of life. Kaplan-Meier survival curves were calculated., Results: Among a total of 18,126 ICU admissions, 223 patients required more than 30 days ICU treatment; 25% died in the ICU; 14% died after discharge from the ICU, but still in the hospital; 31% of the patients were discharged to another hospital or nursing home. Of all patients 50% eventually reached home. Two months after ICU discharge 75% were alive, after 1 year 50%. Mean survival time was 36 months (SD: 3). Patients under 60 years of age and those who were discharged directly home had the best prognosis. 30% of the protracted IC patients could ultimately function independently at home., Conclusions: Patients who needed more than 30 days ICU treatment had a high ICU mortality; 2 months after discharge 75% were alive.

The influence of 51 preoperative, peroperative and postoperative variables on the development of serious acute renal failure (ARF) following open heart surgery was studied. Although a large number of significant variables was found, a logit-model with only 2 explanatory variables showed an almost perfect fit. With this model the chances of serious ARF up to 90% were estimated. The results suggest that a critical circulation is the main cause of serious ARF. Furthermore, a reduced ability to cope with a critical circulation without renal failure plays an important role in the pathogenesis. There is a higher risk of serious ARF for patients older than 70, especially when circulatory support with dopamine is needed.

Cardiotomy suction causes platelet damage and hemolysis due to air aspiration along with blood suction (uncontrolled suction = US). However, prevention of air aspiration (controlled suction = CS) reduces platelet damage and hemolysis and improves postoperative hemostasis, as only attainable in membrane oxygenator (MO) perfusions. We therefore studied 3 groups of patients subjected to extracorporeal circulation: bubble oxygenator (BO) with CS (n = 10), BO with US (n = 8) and MO with US (n = 10). If CS was used during BO perfusions we found that only hemolysis was significantly reduced, if compared to BO perfusions with US. Despite the use of CS during BO perfusions, platelets were still significantly better preserved during MO perfusions in which US was used. This was indicated by a higher platelet number, higher ADP-induced platelet aggregation, and lower beta-thromboglobulin plasma concentration, during and immediately after MO perfusions. Blood loss and blood transfusions during the first 18 hours after perfusion were not significantly different between the 3 groups. We conclude that the platelet-preserving capacity of CS is completely lost by the platelet damaging effect of the BO. However, reduction in hemolysis is well maintained.

To determine whether the large volumes of cardiotomy suction which occur during long perfusions can obscure the hematological advantage of the membrane oxygenator (MO) over the bubble oxygenator (BO), we studied 23 patients undergoing a coronary artery bypass grafting operation with an expected perfusion time of 3 hours (MO group, N = 10, SciMed spiral coil; BO group, N = 13, Shiley 100-A). During MO perfusion we found significantly higher platelet numbers, better platelet function (adenosine diphosphate-induced platelet aggregation), and less hemolysis (plasma hemoglobin), than during the BO perfusion. After the MO perfusion we measured significantly shorter bleeding times (Simplate II) and fewer transfusions of blood products. However, blood loss and whole-blood transfusions 18 hours after perfusion did not differ significantly between both groups. So in coronary artery bypass grafting operations with long perfusion times (mean, 3 hours), the MO still causes significantly less platelet and erythrocyte damage than the BO, despite the large volumes of cardiotomy suction known to occur during these operations.

The new Cobe CML membrane oxygenator is more compact than other membrane oxygenators and has a combined venous and cardiotomy suction reservoir. Its size makes it as easy to use as a bubble oxygenator. The studies reported here were designed to show whether the excellent haemocompatibility found with other types of membrane oxygenators had ben compromised by the changes introduced in the Cobe CML oxygenator. Platelet number and function (ADP induced aggregation) plasma betathromboglobulin concentration and plasma haemoglobulin concentration were studied in nine patients where the Cobe CML oxygenator had been used and these were compared with ten patients managed with a Shiley S-100 bubble oxygenator. We conclude that the constructional changes of the Cobe CML oxygenator do not affect the haemocompatibility of this type of membrane oxygenator and that it remains significantly better than the Shiley S-100 bubble oxygenator.

Sixteen patients who had undergone open heart surgery were studied in order to determine the factors influencing cardiac performance in the postoperative period. Hemodynamic influences during and following cardiopulmonary bypass were found to be more important than the preoperative cardiac function. The flow rate used during cardiopulmonary bypass had a pronounced influence on the post-operative cardiac performance. A low flow can result in the development of vasoconstriction postoperative with an increased chance of low cardiac output. A high flow during bypass is recommended, and in the postoperative period vasoconstriction must be treated vigorously to forecome low cardiac output.

In order to detect changes in renal perfusion and function in the postoperative period of open heart surgery, a prospective study of 21 patients following open heart surgery was performed. Cardiac output, renal blood flow, glomerular filtration and renal function parameters were determined during intermittent positive pressure ventilation (IPPV), and during spontaneous ventilation (SV). During IPPV, renal perfusion was found to be substantially decreased. The glomerular filtration rate was also reduced, but to a lesser extent, implying that the changes were due to a selective increase in postglomerular vascular resistance. The clearances of urea and creatinine were decreased during IPPV, but the clearances of osmoles and potassium were higher. The reabsorption of sodium, potassium and osmoles were also decreased during IPPV, but not that of urea. These findings are consistent with the development of increased renal venous pressure during IPPV, caused by impeded venous return to the heart. In the low cardiac output range a cardiac index in excess of 0.5l/min/m2 during IPPV seems necessary to achieve the same renal perfusion as during SV.

The effect of cardiopulmonary bypass (CPB) on pulmonary function was investigated in 32 adult patients, including 23 patients undergoing coronary artery bypass grafting and nine patients undergoing heart-valve replacement. Clinical indicators for pulmonary insufficiency, such as chest X-ray, gas exchange and lung function tests were measured. Transthoracic electrical impedances were measured, and the mean specific thoracic impedance (RHO) was calculated. (RHO is an accurate indicator for the intrathoracic fluid content; low RHO values correspond with high intrathoracic fluid content.) Significant postoperative decreases in RHO were paralleled by a significant impairment of gas exchange. Chest X-rays demonstrated accumulation of intrathoracic fluid. Lung function tests showed significant postoperative decreases in lung volumes and vital capacity. These findings are consistent with the concept that CPB provokes an inflammatory reaction in the lung. The non-invasive RHO measurement proved to be simple and in good agreement with clinical indicators. This method may be a real asset in the prevention and treatment of pulmonary dysfunction after CPB. The possibility of calibrating RHO with respect to absolute values of intrathoracic fluid content should be investigated.