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Biomedical subjects

P Nightingale

Publications and source records attributed to P Nightingale.

At least 37 records · Page 2Linked to original sources
PubMed1998

Sources of error in bioimpedance spectroscopy.

Two different makes of bioimpedance spectrometer (UniQuest-SEAC SFB-3 and Xitron 4000B) were used for a series of measurements on volunteers and patients in intensive care. Although each machine was accurate over the frequency range 5 to 500 kHz when bench tested on model resistor-capacitor circuits, significant differences in their recorded impedance parameters appeared when used in vivo, especially on intensive care patients. A series of laboratory tests was performed on each machine simulating the situation in vivo to identify possible reasons for these differences. Whilst stray capacitance in the environment was identified as the major contributor to variability in high-frequency performance, interaction between electrode impedance and lead positioning was also a factor. The observed phase shift with frequency or time delay (Td) used in the Xitron modeling software appears to be the result of a time constant caused by stray capacitance and so is unlikely to have any biological meaning. Significant differences in the in vivo numerical values produced by bioimpedance spectrometers may be attributed to instrument design, data processing and, in particular, the clinical environment.

Adult↗
PubMed1998

Changes in arterial-mixed venous oxygen content difference (CaO2 - CvO2) and the effect on shunt calculations in critically ill patients.

Many commonly used indices of pulmonary oxygen transfer assume that CaO2 - CvO2 is constant. We studied changes in CaO2 - CvO2 in critically ill patients to determine the effect on calculated shunt of assuming a fixed CaO2 - CvO2. Two hundred pairs of arterial and mixed venous blood gas measurements were obtained retrospectively from 43 patients, each providing four or five pairs from a period of 48 h. CaO2 - CvO2 range from 13 to 74 ml l-1. The mean within-patient sd was 6.8 ml l-1 and the overall between-patient sd was 10.9 ml l-1. Our results show that assuming a fixed CaO2 - CvO2 leads to errors in quantifying pulmonary oxygen transfer.

Critical Care↗
PubMed1997

Liver transplantation for alcoholic liver disease: evaluation of a selection protocol.

We have used a formal transplant protocol to select patients with alcoholic liver disease (ALD) for transplantation. We retrospectively analyzed all the patients with ALD who were referred specifically for transplantation to our Liver Unit between 1987 and 1994. Patients were selected for liver transplantation if they had end-stage liver disease and had remained abstinent from the time they were medically advised to stop alcohol intake. Of the 180 patients referred for transplantation, 43 (none of whom were transplanted) had case records insufficiently complete for full analysis; this may bias the analysis. Of the remaining 137 patients, 39 were transplanted and 4 were awaiting transplantation at the time of analysis. Of the patients who were not accepted for transplantation, 13 died during the assessment, 7 were considered to be unlikely to survive the procedure, 29 were found to be medically unsuitable, 16 psychologically unsuitable, 7 patients refused the offer of transplantation, and an additional 19 either showed clinical improvement or were considered too well for transplantation. Special investigations, such as brain computerized tomography (CT) scan and echocardiograph, changed the clinical decision to transplant in only a small number of cases (4% and 5%, respectively). Nine of the transplanted patients died and the remaining were followed up for a median of 25 (range, 7-63) months. One year actuarial survival for the transplanted patients was 79%, for those considered too sick was 0%, for medically unsuitable patients was 44%, for psychologically unsuitable patients was 65% and for those considered too well was 94%. Only 5 of the transplanted patients (13%) reverted to drinking. The observed actuarial survival of nontransplanted patients was compared with the expected survival calculated by 'the Beclere model.' The observed actuarial survival in the nontransplanted groups was much better than anticipated from the Beclere model, which therefore, is not applicable to our patients. The proportional hazards regression analysis of our nontransplanted patients identified serum bilirubin, serum albumin, blood urea, ascites, and spontaneous bacterial peritonitis as factors significantly predictive of their probability of survival. Using a model based on these parameters, the expected survival of our transplanted patients was calculated. Although we applied the model to a different population, the observed actuarial survival in the transplanted patients was found to be better than their expected survival (P < or = .001). Our protocol was useful in selecting suitable patients with ALD for liver transplantation, which resulted in significant survival advantage with low recidivism rate.

Adult↗
PubMed1997

Early indicators of prognosis in fulminant hepatic failure: an assessment of the King's criteria.

BACKGROUND/AIMS: An accurate and early assessment of the individual patient is critical in deciding whether liver transplantation is indicated in the treatment of fulminant hepatic failure. Based on analysis of patients treated between 1973 and 1985, the Liver Unit at King's College Hospital, London, developed a prognostic model to identify patients with a poor prognosis. The present study was done to determine the applicability of this model in fulminant hepatic failure patients seen at our center in the 1990s. METHODS: The records of 145 patients with fulminant hepatic failure, treated conservatively at Queen Elizabeth Hospital, Birmingham between 1990 and 1994, were analyzed. An additional 81 patients, who were transplanted for fulminant hepatic failure during the same period were excluded from the study. RESULTS: Application of King's College Hospital criteria at the time of admission to this hospital in the acetaminophen group, had a positive predictive value of 88%, negative predictive value of 65% and predictive accuracy of 71%. The positive predictive value, negative predictive value and predictive accuracy of these criteria for non-acetaminophen-induced fulminant hepatic failure, were 79%, 50% and 68%. Multivariate analysis identified prothrombin time, serum creatinine, white cell count and abnormal potassium levels as independent predictors of mortality in acetaminophen-induced fulminant hepatic failure; and prothrombin time alone in fulminant hepatic failure induced by other etiologies. CONCLUSIONS: The King's College Hospital criteria for predicting outcome of fulminant hepatic failure were found to have a slightly lower predictive accuracy than shown in the original study.

Acetaminophen↗
PubMed1997

Measles virus serology in Crohn's disease.

BACKGROUND: There is evidence that measles virus infection in early life may predispose to Crohn's disease. AIMS: To examine using serological methods a potential association between measles virus infection in early life and predisposition to Crohn's disease. SUBJECTS: Forty five patients with Crohn's disease and forty five healthy controls were studied prospectively. METHODS: Clinical data were recorded and serum was analysed for measles virus, cytomegalovirus (CMV), adenovirus and herpes simplex virus (HSV) antibody titres by a complement fixation test (CFT), and for measles virus IgM by enzyme linked immunosorbent assay (ELISA). RESULTS: Reciprocal CFT titres for measles virus were lower in patients with Crohn's disease compared with controls (p < 0.05); there was no significant difference in titres for other viruses. None of the subjects studied had a level of measles virus IgM suggestive of acute infection, and there was no significant difference in measles virus IgM levels between patients and controls. The measles virus CFT titres and IgM levels in the patients with Crohn's disease did not correlate with any of the clinical features recorded. CONCLUSION: This study does not provide supportive evidence for a role for measles virus in the aetiology of Crohn's disease.

Adenoviridae↗
PubMed1995

Sex mismatch as a risk factor for chronic rejection of liver allografts.

Chronic irreversible rejection is a major cause of graft loss and retransplantation after orthotopic liver allotransplantation. To identify risk factors we retrospectively analysed 423 adult consecutive primary liver allograft recipients. The endpoint of the study was graft failure due to chronic rejection leading either to retransplantation or death. Chronic rejection developed in 22 (5.2%) patients. Pretransplant diagnosis of primary biliary cirrhosis or autoimmune hepatitis, recipient age less than 30 years, 1 or more episodes of acute cellular rejection, and transplantation of an organ from cytomegalovirus (CMV). IgG positive donor to an IgG negative recipient were identified as risk factors for chronic rejection. Transplantation of a liver from a male donor into a female recipient was also associated with an increased probability of chronic rejection. By logistic regression analysis, the probability of chronic rejection was predicted by: sex and cytomegalovirus match of donor and recipient, the presence of acute rejection, recipient age, transplantation for autoimmune hepatitis or primary biliary cirrhosis, and recipients receiving no azathioprine during the third month after transplantation. Sensitisation to antigens expressed by bile-duct epithelium as in primary biliary cirrhosis or exposure to donor bile-duct minor histocompatibility antigens, such as the male sex related H-Y antigen, may provide an explanation. More selective allocation of donor organs may allow a reduction in the incidence of ductopaenic rejection and graft loss.

ABO Blood-Group System↗
PubMed1995

Interobserver variation in the chest radiograph component of the lung injury score.

The lung injury score is a semi-quantitative system used in the definition and grading of the acute respiratory distress syndrome. It is composed of two, three or four equally weighted components. One component is derived from the chest radiograph, which may contribute up to 50% of the total score. A score of 1 is awarded for each quadrant on the chest radiograph which contains alveolar consolidation. We examined the interobserver variation between two anaesthetists, two radiologists and two critical care physicians who scored blindly 100 chest radiographs from patients with adult respiratory distress syndrome. There was very good agreement between the two radiologists in the total scores (kappa 0.97) and in individual scores in each of the 4 quadrants (kappa 0.97-1.0). The agreement between anaesthetists and radiologists was only fair for the total score (kappa 0.37-0.42), but moderate to good for individual quadrant scores (kappa 0.43-0.73). The agreement between the two anaesthetists was moderate for individual quadrant scores (kappa 0.44-0.60), but only fair for total score (kappa 0.34). There was poor agreement between the two critical care physicians for total score (kappa 0.05) and for individual quadrant scores (kappa 0.04-0.20). Agreement between the physicians and other observers was poor to fair for the total score (kappa 0.12-0.32) and poor to moderate for the individual quadrant scores (kappa 0.15-0.63). Both anaesthetists and physician 2 underestimated the overall chest scores (median scores 2, 3 and 1 respectively) in comparison to the radiologists (median scores 3.5). Physician 1 significantly overscored (median score 4). The chest radiograph component of the lung injury score can be consistently assessed by radiologists, but significant variations may be introduced when assessed by other clinicians. This has significant implications for the use of the lung injury score in studies of adult respiratory distress syndrome and other studies which incorporate radiographic appearances in the definition.

Acute Disease↗
PubMed1994

Comparison of the hemodynamic and oxygen transport responses to modified fluid gelatin and hetastarch in critically ill patients: a prospective, randomized trial.

OBJECTIVE: To compare the hemodynamic and oxygen transport responses to a rapid (< 10-min) infusion of 500 mL of modified fluid gelatin (group A) or hydroxyethyl starch (group B) in patients suffering from acute hypovolemia. DESIGN: Prospective, randomized, noncrossover study. SETTING: University hospital, general intensive care unit. PATIENTS: Twenty-eight patients with hypovolemia mechanically ventilated for concurrent acute respiratory failure. INTERVENTIONS: Patients were mechanically ventilated. Pulmonary and femoral artery catheters were used for hemodynamic monitoring. MEASUREMENTS AND MAIN RESULTS: Hemodynamic and oxygen transport variables were determined at baseline, 15 mins, and 30 mins after the infusion of each fluid. In both groups pulmonary artery occlusion pressure, stroke volume, and cardiac index significantly increased. In neither group did heart rate decrease. Oxygen delivery increased significantly in group A patients but not in group B patients. This result was due to greater hemodilution in group B patients. CONCLUSIONS: There are no significant differences in the hemodynamic responses to hydroxyethyl starch or modified fluid gelatin. The hemodynamic and oxygen transport effects of artificial colloid solutions may not be entirely predictable and should be monitored in critically ill patients.

Adult↗
PubMed1994

The need for quality control in measurement of mixed venous oxygen saturation.

We investigated the variability of arterial, mixed venous and peripheral venous oxygen saturation readings in three co-oximeters in regular use on two Intensive Care Units. Over a 2-week period, 96 readings were obtained from each of the following machines; two AVL 912 co-oxylite co-oximeters (Machines A and B, Biomedical Instruments, Graz, Austria) and one IL-282 (Machine C, Instrumentation Laboratories, Lexington, MA, USA). The coefficient of variation in the arterial oxygen saturations was extremely small on all three machines (< 0.43%). The coefficient of variation in the mixed venous samples, however, ranged from 1.96 to 4.61% on machine A, and from 2.73 to 4.71% on machine B, but only from 0.17 to 1.47% on machine C. The variation in mixed venous saturations obtained from a single blood sample repeatedly analysed on machines A and B was large enough to influence clinical management.

Humans↗
PubMed1994

A re-evaluation of the ventilator score as an indicator of prognosis in the adult respiratory distress syndrome.

OBJECTIVE: To determine whether the ventilator score of Smith and Gordon (1986) can accurately predict outcome in patients with severe Adult Respiratory Distress Syndrome (ARDS). DESIGN: Retrospective study of data from case records and flow sheets. SETTING: University Hospital Intensive Care Unit. SUBJECTS: Fifty-five patients with severe Adult Respiratory Distress Syndrome. MEASUREMENTS AND MAIN RESULTS: The ventilator score of Smith and Gordon (1986), based on a compound score of the patient's age, alveolar to arterial oxygen tension difference and mean peak airway pressure, was calculated daily for for each patient. In contrast to the original report, a high ventilator score ( greater than 80) had a predictive value for death of only 59%, and a specificity of only 29%. The use of a higher ventilator score ( greater than 100) resulted in a predictive value of only 70% with a specificity of 75%. The use of inverse ratio ventilation was associated with a significant improvement in survival in those patients with ventilator scores greater than 100. This finding has not been reported previously. CONCLUSIONS: The ventilator score does not provide a satisfactory predictor of outcome in ARDS and cannot be used as a prognostic tool. It may have some use as an indicator of the severity of respiratory failure. A ventilator score greater than 100 may be an indication for the institution of inverse ratio ventilation.

Adolescent↗
PubMed1993

Influence of an anti-tumor necrosis factor monoclonal antibody on cytokine levels in patients with sepsis. The CB0006 Sepsis Syndrome Study Group.

OBJECTIVES: To determine the safety, pharmacokinetics, and activity of an anti-tumor necrosis factor (TNF)-alpha monoclonal antibody in severe sepsis. DESIGN: Open-label, prospective, phase II multicenter trial with escalating doses of a murine monoclonal antibody (CB0006). SETTING: Twelve academic medical center intensive care units in the United States and Europe. PATIENTS: Eighty patients with severe sepsis or septic shock who received standard supportive care and antimicrobial therapy in addition to the anti-TNF antibody. INTERVENTIONS: Patients were treated intravenously with one of four dosing regimens with CB0006: 0.1 mg/kg, 1.0 mg/kg, 10 mg/kg or two doses of 1 mg/kg 24 hrs apart. MEASUREMENTS AND MAIN RESULTS: The murine monoclonal anti-TNF antibody was well tolerated despite the development of anti-murine antibodies in 98% of patients. No survival benefit was found for the total study population, but patients with increased circulating TNF concentrations at study entry appeared to benefit by the high dose anti-TNF antibody treatment. Increased interleukin (IL)-6 levels predicted a fatal outcome (p = .003), but TNF levels were not found to be a prognostic indicator. TNF levels were higher (206.7 +/- 60.7 vs. 85.9 +/- 26.1 pg/mL; p < .001) and outcome was poor (41% vs. 71% survival; p = .007) in patients who were in shock at study entry when compared with septic patients not in shock. CONCLUSIONS: The murine anti-TNF-alpha monoclonal antibody CB0006 has proven to be safe in this clinical trial and may prove to be useful in septic patients with increased circulating TNF concentrations. Further studies are needed to determine efficacy and the ultimate clinical utility of this immunotherapeutic agent in sepsis.

Antibodies, Monoclonal↗
PubMed1992

Early cardiorespiratory findings after severe blunt thoracic trauma and their relation to outcome.

This study examined the initial haemodynamic and oxygen transport patterns in 24 patients with severe blunt thoracic trauma in whom immediate monitoring with femoral and pulmonary artery catheters was required after admission to the intensive care unit. All patients required mechanical ventilation and were studied before receiving inhalational anaesthesia and within 12 h of injury. Two groups of patients were identified; nine patients (group 1) had an impaired left ventricular stroke work index (LVSWI) and 15 patients had a normal LVSWI (group 2). There were no significant differences in the abbreviated injury scale score for the chest, the total injury severity score, or the mean ages of the two groups. There were significant differences in stroke volume index, 32 versus 56 ml m-2 (P less than 0.001), and cardiac index, 3.2 versus 5.3 l min-1 m-2 (P less than 0.001), and therefore in oxygen delivery, 469 versus 852 ml min-1 m-2 (P less than 0.001), despite apparently adequate volume expansion using the same protocol and clinical criteria in both groups. Oxygen consumption was not significantly different in the two groups, 135 versus 157 ml min-1 m-2, because of a higher oxygen extraction ratio in group 1, 29 versus 19 per cent (P less than 0.001), and hence lower mixed venous oxygen saturation, 73 versus 82 per cent (P less than 0.02). Seven patients in group 1 died (78 per cent) compared with two in group 2 (13 per cent). Early depression of cardiac function is associated with poor outcome in patients with thoracic trauma, and measurements of oxygen transport variables may influence resuscitation and the timing of surgical procedures.

Cardiac Output↗