Acetylcysteine as a cytoprotective antioxidant in patients with severe sepsis: potential new use for an old drug

OBJECTIVE

To stimulate debate regarding a potential new use for acetylcysteine as a cellular antioxidant in severely septic patients with systemic inflammatory response syndrome (SIRS).

DATA SOURCES

A MEDLINE review of published animal, human, and laboratory studies relating to the cytopathogenic effects of active radicals in SIRS and the protective effects of acetylcysteine and glutathione.

STUDY SELECTION

Few studies were available so all studies pertinent to the objective were reviewed.

DATA EXTRACTION

Clinical and basic science data from the available trials of the effects of acetylcysteine on active radical production or active radical cell injury were extrapolated to predict the effect of acetylcysteine on human sepsis.

DATA SYNTHESIS

Severe sepsis is a major cause of SIRS. Much of the cellular injury associated with SIRS is mediated by active radicals produced by inflammatory cells that overwhelm endogenous antioxidants. Reduced glutathione is a crucial intracellular antioxidant that becomes depleted during SIRS. Regeneration of glutathione can be achieved by acetylcysteine, which unlike glutathione itself penetrates cells. In animal models of sepsis and lung injury, acetylcysteine mitigates the cytopathologic effects of SIRS. In humans, clinical benefit has been demonstrated in the SIRS of established fulminant hepatic failure.

CONCLUSIONS

The data do not as yet lead to any firm conclusions regarding the value of acetylcysteine in the management of SIRS in severe sepsis. The animal and human studies are, however, sufficiently encouraging to warrant formal trials to test the hypothesis that acetylcysteine therapy has a cytoprotective effect in sepsis.

Failure of intravenous low dose midazolam to influence memory recall in drug paralysed post-operative patients sedated with papaveretum

Sedation of ventilated patients in the Intensive Care Unit generates a tension between adequate sedation to maintain comfort and ease of ventilation and over sedation with undesirable prolongation of ventilation and delays in discharge. Studies in animals suggest very low dose midazolam, but not higher doses, potentiate the sedative effects of opiates. We undertook a trial of opiate sedation versus opiate sedation plus low dose midazolam (1 mg/hour) to determine whether a similar effect could be demonstrated in man. Although ventilator time and the duration of admission to Intensive Care was not prolonged by the addition of midazolam, we were unable to demonstrate any statistically significant benefit with regard to memory recall.

The significance for critical care nurses of the "dying with dignity" legislation

This paper examines the potential contribution of the critical care nurse to ethical decisions made with respect to the dying with dignity legislation. The literature to date on ethics in nursing has largely focused on increasing nurses awareness thereby encouraging their contribution to the ethical decision-making process. By accentuating the 'art of nursing' where forms of knowing encompass an understanding of the patient's experience, this article describes the unique contribution that the nurse can make to the specific area of 'dying with dignity' in the acute care setting. On a theoretical level this knowledge is invaluable as it ensures a range of constituents are accommodated in this decision-making process, however, in practice this ideal is not readily attainable. Firstly, tradition seeks to curtail the value of this form of nursing knowledge in the decision-making process and secondly, nurses need to recognise their own prejudices in order to make an appropriate contribution to this legitimate body of knowledge.

Effect of postoperative low-dose dopamine on renal function after elective major vascular surgery

OBJECTIVE

To determine the effect on renal function of postoperative low-dose dopamine in volume-replete patients after elective, major vascular abdominal surgery.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Intensive care unit of a referral hospital in Brisbane, Australia.

PATIENTS

37 patients having elective repair of an abdominal aortic aneurysm or having aortobifemoral grafting; 18 received dopamine, and 19 received placebo. Two patients were excluded from the 5-day analysis because of perioperative death.

INTERVENTIONS

Patients were randomly assigned to receive either placebo or a low-dose infusion of dopamine (3 micrograms/kg per minute) in saline. Patients in both groups were given sufficient crystalloid to maintain a urine flow of more than 1 mL/kg per hour during the first 24 postoperative hours. Care in the intensive care unit was otherwise usual and was the same for each group.

MEASUREMENTS

Plasma creatinine levels, urea levels, and creatinine clearance were measured preoperatively and postoperatively (at 24 hours and 5 days). Urine flow and the volume of crystalloid during the first 24 hours were recorded.

RESULTS

Two postoperative deaths occurred in the dopamine group (from renal failure and myocardial infarction). Four patients had myocardial infarction, three of whom received dopamine. Plasma creatinine levels remained unchanged in both groups. At 24 hours, the mean plasma urea level decreased by 1.07 mmol/L in the dopamine group compared with 1.84 mmol/L in the placebo group, a difference of 0.77 (95% CI, -0.12 to 1.67). The mean 24-hour creatinine clearance increased by 0.165 mL/s (9.89 mL/min) in the dopamine group and by 0.199 mL/s (11.98 mL/min) in the placebo group (P > 0.2). Urine volumes were slightly higher in those receiving dopamine (1.83 mL/kg compared with 1.6 mL/kg, a difference of 0.23 [CI, -0.18 to 0.64]). None of these differences were statistically or clinically significant.

CONCLUSIONS

Within the limits of the small size of the study, low-dose dopamine appeared to offer no advantage to euvolemic patients after elective abdominal aortic surgery. However, patients with acute oliguric renal failure were not included in the study.

Serum lipids and apolipoproteins and their relationship with macrovascular disease in type 1 diabetes

In order to examine the relationship between serum lipids and apolipoproteins and macrovascular disease in patients with Type 1 diabetes mellitus, 50 patients with Type 1 diabetes mellitus attending the diabetic clinics at St Mary's and St Charles' Hospitals, London were recruited into a cross-sectional study. B-mode ultrasound was used to measure intima-media thickness and define an arterial ultrasound score for each patient as a non-invasive indicator of atherosclerotic change. Intima-medial (i-m) thickness was significantly higher in those subjects with clinical evidence of macrovascular disease compared to those without macrovascular disease (0.865 +/- 0.191 vs 0.695 +/- 0.162 mm, p = 0.0038). In the study group there were significant correlations between i-m thickness and age (r = 0.65, p < 0.01), total serum cholesterol (r = 0.32, p < 0.01), and serum fibrinogen (r = 0.43, p < 0.01) but no other lipid or apolipoprotein variable. When i-m thickness was corrected for age there were significant correlations with total cholesterol (r = 0.43, p < 0.01) and LDL-cholesterol (r = 0.42, p < 0.01). Whereas total and LDL-cholesterol and serum fibrinogen concentrations were related to the extent of atherosclerotic disease by ultrasound techniques, there was no relationship with high density lipoprotein (HDL) or subfraction cholesterol concentrations. HDL-cholesterol may not be a useful marker for cardiovascular disease in Type 1 diabetes.

Charts of fetal size: 3. Abdominal measurements

OBJECTIVE

To construct new size charts for fetal abdominal circumference and area.

DESIGN

A prospective, cross sectional study.

SETTING

The routine ultrasound department of a London teaching hospital.

SUBJECTS

The fetuses of 663 women seen in the routine antenatal booking clinic whose ultrasound and menstrual dates agreed within 10 days.

METHODS

Fetuses were scanned once only for the purpose of the study at gestations between 12 and 42 weeks, when up to 20 dimensions were measured. Separate regression models were fitted to estimate the mean and standard deviation as functions of gestational age. Centiles were derived by combining these two regression models, assuming that the measurements have a Normal distribution at each gestation.

RESULTS

A total of 610 fetuses had their abdominal circumference measured directly. Abdominal diameters were recorded for 425 fetuses and the circumference was also derived from these, as was the abdominal area. New charts for abdominal circumference (directly measured and derived from diameters) are presented. The directly measured circumferences were consistently (by about 3.5%) greater than those derived from measurement of the abdominal diameters. The new charts are compared with previously published charts that are in wide use. A chart for abdominal area is also presented.

CONCLUSIONS

We have constructed new size charts for the fetal abdominal circumference, both measured directly and derived from abdominal diameters. We have demonstrated the difference between the size charts constructed from these two sets of values and hence the importance of using the appropriately derived chart when assessing the abdominal circumference. The differences between the new charts and previous ones may be largely due to methodological differences.

Charts of fetal size: 4. Femur length

OBJECTIVE

To construct a new size chart for fetal femur length.

DESIGN

A prospective, cross sectional study of fetuses scanned once only for the purpose of the study at gestations between 12 and 42 weeks.

SETTING

The routine ultrasound department of a London teaching hospital.

SUBJECTS

The fetuses of 663 women seen in the routine antenatal booking clinic whose ultrasound and menstrual dates agreed within 10 days.

RESULTS

Femur length was measured on 649 of the 663 fetuses. A linear-cubic regression model was fitted to estimate the mean and a separate linear regression to estimate the standard deviation. Centiles were derived by combining these two regression models, assuming that the measurements have a normal distribution at each gestational age. A new chart for femur size is presented and compared with previously published data.

CONCLUSIONS

We have constructed a new size chart for fetal femur length taking into consideration the increasing variability with increasing gestational age. We have compared our chart with other published data, and believe that the differences seen may be largely due to methodological differences.

The effects of gender and type of diabetes on HDL-cholesterol

OBJECTIVE

To investigate the influence of gender and type of Diabetes on plasma lipoproteins and post-heparin plasma lipoprotein lipase and hepatic lipase activities.

DESIGN AND PATIENTS

Cross sectional study of 22 lean Type 2 diabetic subjects (11 men, 11 women) individually matched for gender, BMI and HbA1 with 22 Type 1 (C-peptide negative) diabetic subjects.

MEASUREMENTS

Samples were taken for fasting lipids and post heparin samples were obtained for estimation of post heparin lipolytic activity.

RESULTS

In men, HDL-Cholesterol was higher in Type 1 diabetes [1.56 (range 0.97-2.27) vs 1.07 (0.54-1.78) mmol/l, p = 0.009] and this was reflected in both HDL2-cholesterol [0.42 (0.02-1.36) vs 0.22 (0.01-0.90) mmol/l, p = 0.05] and HDL3-cholesterol [1.00 (0.75-1.51) vs 0.72 (0.53-0.87) mmol/l, p = 0.02] subfractions while serum triglyceride concentrations were similar. Lipoprotein lipase activity was higher in men with Type 1 diabetes [16.2 (6.2-42.4) vs 9.77 (5.6-22.6) mmol/h/l, p = 0.02] while hepatic lipase activities were similar [15.7 (9.3-23.0) vs 14.0 (6.8-24.0) mmol/h/l, NS). In women, there were no significant differences between Type 1 and Type 2 diabetes in triglycerides, HDL-C, HDL2 or HDL3. Lipoprotein lipase activity was higher in Type 1 women [19.3 (14.1-35.7) vs 11.0 (7.2-15.2) mmol/h-1 1-1, p = 0.0006] but lipatic lipase activity was also higher [12.1 (4.8-20.5) vs 7.3 (2.3-21.4) mmol/h-1 1-1, p = 0.023].

CONCLUSION

In non-obese diabetic subjects, men with Type 1 diabetes have higher HDL-cholesterol than those with Type 2 diabetes, possibly due to the action of peripheral insulin on lipoprotein lipase activity, while in women, HDL-cholesterol concentrations were similar in Type 1 and Type 2 subjects possibly because of lowered lipatic lipase activity in Type 2 women which offsets the increased lipoprotein lipase activity of the Type 1 women.

Charts of fetal size: 2. Head measurements

OBJECTIVE

To construct new size charts for fetal head circumference, biparietal diameter and other head dimensions.

DESIGN

A prospective, cross sectional study.

SETTING

The routine ultrasound department of a London teaching hospital.

SUBJECTS

The fetuses of 663 women seen in the routine antenatal booking clinic whose ultrasound and menstrual dates agreed within 10 days.

METHODS

Fetuses were scanned once only for the purpose of the study at gestations between 12 and 42 weeks, when up to 20 dimensions were measured. For each measurement separate regression models were fitted to estimate the mean and standard deviation at each gestational age. Centiles were derived by combining these two regression models, assuming that the measurements have a normal distribution at each gestational age.

RESULTS

A total of 594 fetuses had their biparietal diameter measured and their head circumference measured directly. Both head diameters were recorded for 587 fetuses and the circumference was also derived from these, as was the cephalic area. New charts are presented for biparietal diameter (both outer-outer and outer-inner), head circumference (directly measured and derived from diameters). The directly measured head circumferences were consistently (by about 1%) greater than those derived from measurement of the head diameters. The new charts are compared with previously published charts that are in wide use. Charts for occipitofrontal diameter, cephalic index and cephalic area are also presented.

CONCLUSIONS

We have constructed new size charts for the fetal biparietal diameter and for head circumference, both measured directly and derived from head diameters. We have demonstrated the difference between the size charts constructed from these two sets of values and hence the importance of using the appropriately derived chart when assessing the head circumference. The differences between the new charts for biparietal diameter and head circumference and previous ones may be largely due to methodological differences.

Use of monoethylglycinexylidide as a liver function test in the liver transplant recipient

The hepatic conversion of lignocaine to monoethylglycinexylidide (MEGX) has been used as a real time monitor of liver function in liver transplant recipients. Data are reported for the first 4 weeks after transplant in 50 consecutive orthotopic liver grafts in 47 adults. The MEGX concentration was significantly depressed by approximately 50% in those patients in whom there was a complicated clinical course (excluding steroid-sensitive rejection) after transplantation, compared with patients in whom major complications did not occur. The MEGX concentration in the recipients after transplant was independent of the donor MEGX concentration, but, in addition to the patient's clinical status, was strongly influenced by the recipients pretransplant biochemical profile, being inversely related to the pretransplant bilirubin concentration. MEGX concentrations < 25 micrograms/L in the first 36 hr after revascularization were predictive of greater morbidity and mortality.

The resource implications of severe necrotizing pancreatitis treated by necrosectomy

This study reviews the resource utilization of patients admitted to the Intensive Care Unit (ICU) with severe necrotizing pancreatitis treated by early necrosectomy. For 21 patients there was a total of 221 abdominal operations, 2365 hospital days, 565 ICU days and 1185 days of parenteral nutrition. The mortality rate was 43%. The treatment for patients with necrotizing pancreatitis is 10 times more resource intense than other admissions to the ICU. The implications of necrotizing pancreatitis treated by necosectomy in the context of a Diagnosis-Related Groups Prospective Payment model of hospital funding are discussed.

Fatal brown snake (Pseudonaja textilis) envenomation despite the use of antivenom

OBJECTIVE

To report two cases of fatal brown snake envenomation in adults despite the use of appropriate antivenom.

CLINICAL FEATURES

Two men, aged 42 and 39, one with a history of hypertension, suffered fatal brown snake envenomation in Queensland. One believed he had been stung by a wasp. Both developed cardiorespiratory failure within one hour of the bite, followed by coagulopathy and pulmonary oedema. One patient developed fulminant multiorgan failure.

INTERVENTION

Both patients died despite the administration of large doses of appropriate antivenom and full supportive care.

CONCLUSION

Brown snake bites remain extremely dangerous despite the availability of specific antivenom. In severe cases associated with myocardial depression and gross coagulopathy, death may occur rapidly despite the use of conventional doses of antivenom. In such patients the antivenom requirement may be much greater than is currently recommended.

Patterns of visual spatial inattention and their functional significance in stroke patients

The relationship between patterns of visual spatial inattention and activities of daily living (ADL) performance was investigated in 64 Chinese patients with right brain lesions, using the Klein-Bell ADL Scale and the Random Chinese Word Cancellation Test. The result showed that patients demonstrating hemi-inattention were significantly worse in ADL performance than patients with nonlateralized inattention or patients with normal attention, but that the latter two groups did not differ from each other. Although ADL performance was also found to be significantly related to somatosensation, motor status, and visual factors, after controlling the effects of these variables by partial correlation, hemi-inattention still was highly related to ADL performance. Independence in dressing, mobility, and elimination appeared to be more adversely affected by hemi-inattention than were bathing/hygiene, eating, and telephone use.

Acute bacterial meningitis in young adults mistaken for substance abuse

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