Association between severe pandemic 2009 influenza A (H1N1) virus infection and immunoglobulin G(2) subclass deficiency

BACKGROUND

. Severe pandemic 2009 influenza A virus (H1N1) infection is associated with risk factors that include pregnancy, obesity, and immunosuppression. After identification of immunoglobulin G(2) (IgG(2)) deficiency in 1 severe case, we assessed IgG subclass levels in a cohort of patients with H1N1 infection.

METHODS

Patient features, including levels of serum IgG and IgG subclasses, were assessed in patients with acute severe H1N1 infection (defined as infection requiring respiratory support in an intensive care unit), patients with moderate H1N1 infection (defined as inpatients not hospitalized in an intensive care unit), and a random sample of healthy pregnant women.

RESULTS

Among the 39 patients with H1N1 infection (19 with severe infection, 7 of whom were pregnant; 20 with moderate infection, 2 of whom were pregnant), hypoabuminemia (P < .001), anemia (P < .001), and low levels of total IgG (P= .01), IgG(1) (P= .022), and IgG(2) (15 of 19 vs 5 of 20; P= .001; mean value +/- standard deviation [SD], 1.8 +/- 1.7 g/L vs 3.4 +/- 1.4 g/L; P= .003) were all statistically significantly associated with severe H1N1 infection, but only hypoalbuminemia (P= .02) and low mean IgG(2) levels (P= .043) remained significant after multivariate analysis. Follow-up of 15 (79%) surviving IgG(2)-deficient patients at a mean (+/- SD) of 90 +/- 23 days (R, 38-126) after the initial acute specimen was obtained found that hypoalbuminemia had resolved in most cases, but 11 (73%) of 15 patients remained IgG(2) deficient. Among 17 healthy pregnant control subjects, mildly low IgG(1) and/or IgG(2) levels were noted in 10, but pregnant patients with H1N1 infection had significantly lower levels of IgG(2) (P= .001).

CONCLUSIONS

Severe H1N1 infection is associated with IgG(2) deficiency, which appears to persist in a majority of patients. Pregnancy-related reductions in IgG(2) level may explain the increased severity of H1N1 infection in some but not all pregnant patients. The role of IgG(2) deficiency in the pathogenesis of H1N1 infection requires further investigation, because it may have therapeutic implications.

Decreased catecholamine degradation associates with shock and kidney injury after cardiac surgery

Enzymatic pathways involving catechol-O-methyltransferase (COMT) catabolize circulating catecholamines. A G-to-A polymorphism in the fourth exon of the COMT gene results in a valine-to-methionine amino acid substitution at codon 158, which leads to thermolability and low ("L"), as opposed to high ("H"), enzymatic activity. We enrolled 260 patients postbypass surgery to test the hypothesis that COMT gene variants impair circulating catecholamine metabolism, predisposing to shock and acute kidney injury (AKI) after cardiac surgery. In accordance with the Hardy-Weinberg equilibrium, we identified 64 (24.6%) homozygous (LL), 123 (47.3%) heterozygous (HL), and 73 (28.1%) homozygous (HH) patients. Postoperative catecholamines were higher in homozygous LL patients compared with heterozygous HL and homozygous HH patients (P < 0.01). During their intensive care stay, LL patients had both a significantly greater frequency of vasodilatory shock (LL: 69%, HL: 57%, HH: 47%; P = 0.033) and a significantly longer median duration of shock (LL: 18.5 h, HL: 14.0 h, HH: 11.0 h; P = 0.013). LL patients also had a greater frequency of AKI (LL: 31%, HL: 19.5%, HH: 13.7%; P = 0.038) and their AKI was more severe as defined by a need for renal replacement therapy (LL: 7.8%, HL: 2.4%, HH: 0%; P = 0.026). The LL genotype associated with intensive care and hospital length of stay (P < 0.001 and P = 0.002, respectively), and we observed a trend for higher mortality. Cross-validation analysis revealed a similar graded relationship of adverse outcomes by genotype. In summary, this study identifies COMT LL homozygosity as an independent risk factor for shock, AKI, and hospital stay after cardiac surgery. (ClinicalTrials.gov number, NCT00334009).

Post-hypoxic myoclonic status: the prognosis is not always hopeless

A 67-year-old woman abruptly developed acute pulmonary oedema, severe bradycardia and then cardiac arrest while in hospital 6 days after an elective hernia repair. She was resuscitated, intubated and transferred to the intensive care unit. Within 24 hours, she began to display repetitive, generalised myoclonic jerks that failed to respond to therapy with conventional anticonvulsants; an electroencephalogram confirmed myoclonic status. After administration of levetiracetam was begun on Day 3, myoclonic jerks reduced, and there was gradual clinical improvement. By Day 6 after the arrest, the patient was alert and oriented (Glasgow Coma Score, 15/15). Although she died on Day 11 after massive haemoptysis and cardiac arrest, this patient demonstrates the possibility of reasonable neurological recovery despite early onset of myoclonic status.

Continuous hemofiltration for anasarca: recovery of renal function after 71 liters of net ultrafiltration

We report on a 64-year-old female presenting with anasarca secondary to volume loading in the setting of chronic liver disease, acute on chronic renal failure, circulatory failure and sepsis. Over 37 days, a net negative fluid balance of 71 L was achieved using continuous hemofiltration, with spontaneous recovery of urine output, vasopressor independence and resolution of coagulopathy. This case report underlines the pathophysiological role of tissue edema in the downward spiral of hepato-renal and cardio-renal dysfunction and illustrates that very large volumes of tissue fluid can be safely and effectively removed with continuous renal replacement therapy, thereby permitting recovery of organ function. To our knowledge, there have been no previous reports of such large volume net fluid removal by progressive ultrafiltration in the intensive care unit.

Effect of an education programme on the utilization of a medical emergency team in a teaching hospital

BACKGROUND

Medical Emergency Teams (MET) have been developed to identify, review and manage acutely unwell ward patients. Previous studies have suggested that there may be obstacles to the utilization and activation of the MET.

AIMS

To determine the effect of a detailed education programme on the rate of utilization of the MET system 3.5 years after its introduction in a University teaching hospital.

METHODS

Prospective interventional study involving a detailed programme of education, feedback and decision support for nursing and medical staff given before, during and after implementation of a MET system. We measured the number of MET calls per month for both medical and surgical patients for 109 250 consecutive admissions to the acute care campus of Austin Health from August 2000 to June 2004.

RESULTS

Overall activation of the MET increased from 25 calls per month to a peak of 79 calls per month over the study period (average increase of one MET call/month). After standardization for monthly admissions, the increase in MET utilization for surgical patients (increase by 1.13 MET/1000 admissions/month) was 4.9-fold greater than for medical patients (increase by 0.23 MET/1000 admissions/month; P < 0.0001). At the peak level of activity (April 2004), the MET was called to review 8.4% of surgical and 2.7% of medical admissions (P < 0.0001).

CONCLUSIONS

There was a progressive increase in the utilization of the MET service in the 3.5 years after implementation, with the rate of uptake 4.9 times greater for surgical than for medical patients. Sustained uptake of the MET system is possible, but increased utilization may take several years to develop. Short-term studies testing the efficacy of the MET system are likely to significantly underestimate its effect on reducing adverse events. Intensive care unit resource adjustments will become necessary to meet increased demand.

Circadian pattern of activation of the medical emergency team in a teaching hospital

INTRODUCTION

Hospital medical emergency teams (METs) have been implemented to reduce cardiac arrests and hospital mortality. The timing and system factors associated with their activation are poorly understood. We sought to determine the circadian pattern of MET activation and to relate it to nursing and medical activities.

METHOD

We conducted a retrospective observational study of the time of activation for 2568 incidents of MET attendance. Each attendance was allocated to one of 48 half-hour intervals over the 24-hour daily cycle. Activation was related nursing and medical activities.

RESULTS

During the study period there were 120,000 consecutive overnight medical and surgical admissions. The hourly rate of MET calls was greater during the day (47% of calls in the 10 hours between 08:00 and 18:00), but 53% of the 2568 calls occurred between 18:00 and 08:00 hours. MET calls increased in the half-hour after routine nursing observation, and in the half-hour before each nursing handover. MET service utilization was 1.25 (95% confidence interval [CI] = 1.11-1.52) times more likely in the three 1-hour periods spanning routine nursing handover (P = 0.001). The greatest level of half-hourly utilization was seen between 20:00 and 20:30 (odds ratio [OR] = 1.76, 95% CI = 1.25-2.48; P = 0.001), before the evening nursing handover. Additional peaks were seen following routine nursing observations between 14:00 and 14:30 (OR = 1.53, 95% CI = 1.07-2.17; P = 0.022) and after the commencement of the daily medical shift (09:00-09:30; OR = 1.43, 95% CI = 1.00-2.04; P = 0.049).

CONCLUSION

Peak levels of MET service activation occur around the time of routine observations and nursing handover. Our findings raise questions about the appropriate frequency and methods of observation in at-risk hospital patients, reinforce the need for adequately trained medical staff to be available 24 hours per day, and provide useful information for allocation of resources and personnel for a MET service.

A before and after trial of the effect of a high-dependency unit on post-operative morbidity and mortality

OBJECTIVE

It has been suggested that the availability of a high-dependency unit (HDU), to facilitate graded admission to, and discharge from, an intensive care unit (ICU), might decrease post-operative morbidity. We wished to determine whether the addition of a 4-bed HDU to a tertiary 17-bed ICU facility at a University-affiliated hospital would decrease post-operative morbidity and mortality.

PATIENTS AND METHODS

A prospective controlled before-and-after trial was performed with the opening of a 4-bed HDU. Consecutive patients admitted to hospital for major surgery during a 4-month control (pre-HDU) phase and during a 4-month intervention (HDU) phase were studied for the incidence of serious adverse events (SAEs), mortality after major surgery and mean duration of hospital stay.

RESULTS

There were 1319 operations performed in 1125 patients during the pre-HDU period and 1369 operations performed in 1127 patients during the HDU period. During the HDU period there was an excess in unscheduled surgery cases (674 during HDU vs. 531 during the pre-HDU period; p < 0.0001). In the pre-HDU period, there were 414 SAEs in 190 patients compared with 456 SAEs in 209 patients during the HDU period (NS). There were no significant changes in any of the individual SAEs measured except for the incidence of post-operative acute pulmonary edema, which increased from 19 cases to 46 during the HDU period (p = 0.028). This increase was associated with a greater number of patients requiring re-intubation (52 vs. 75 cases; p = 0.044). The introduction of an HDU had no effect on mortality (80 deaths vs. 76; NS) and failed to reduce mean hospital length of stay (21.8 vs. 24 days; NS).

CONCLUSIONS

The introduction of a 4-bed HDU in a teaching hospital was associated with a marked increase in unscheduled surgery and failed to reduce the incidence of post-operative SAEs, post-operative mortality, and mean duration of hospital stay.

Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia

BACKGROUND

Cardiac arrest outside the hospital is common and has a poor outcome. Studies in laboratory animals suggest that hypothermia induced shortly after the restoration of spontaneous circulation may improve neurologic outcome, but there have been no conclusive studies in humans. In a randomized, controlled trial, we compared the effects of moderate hypothermia and normothermia in patients who remained unconscious after resuscitation from out-of-hospital cardiac arrest.

METHODS

The study subjects were 77 patients who were randomly assigned to treatment with hypothermia (with the core body temperature reduced to 33 degrees C within 2 hours after the return of spontaneous circulation and maintained at that temperature for 12 hours) or normothermia. The primary outcome measure was survival to hospital discharge with sufficiently good neurologic function to be discharged to home or to a rehabilitation facility.

RESULTS

The demographic characteristics of the patients were similar in the hypothermia and normothermia groups. Twenty-one of the 43 patients treated with hypothermia (49 percent) survived and had a good outcome--that is, they were discharged home or to a rehabilitation facility--as compared with 9 of the 34 treated with normothermia (26 percent, P=0.046). After adjustment for base-line differences in age and time from collapse to the return of spontaneous circulation, the odds ratio for a good outcome with hypothermia as compared with normothermia was 5.25 (95 percent confidence interval, 1.47 to 18.76; P=0.011). Hypothermia was associated with a lower cardiac index, higher systemic vascular resistance, and hyperglycemia. There was no difference in the frequency of adverse events.

CONCLUSIONS

Our preliminary observations suggest that treatment with moderate hypothermia appears to improve outcomes in patients with coma after resuscitation from out-of-hospital cardiac arrest.

Early and intensive continuous hemofiltration for severe renal failure after cardiac surgery

BACKGROUND

The aim of this study was to test whether early and intensive use of continuous venovenous hemofiltration (CVVH) achieved a better than predicted outcome in patients with severe acute renal failure undergoing cardiac operations, and whether a simple and yet accurate model could be developed to predict their outcome before starting CVVH.

METHODS

Medical record analysis with collection of demographic, clinical, and outcome information was used.

RESULTS

Sixty-five consecutive patients were treated with early and intensive CVVH (mean operation to CVVH time, 2.38 days; pump-controlled ultrafiltration rate, 2 L/h) after coronary artery bypass grafting (56.9%), single valve procedure (16.9%), or combined operations (26.2%). In 32.3% of patients, intraaortic balloon counterpulsation was required and 20% of patients were emergencies. Sustained hypotension despite inotropic and vasopressor support occurred in 40% of patients and prolonged mechanical ventilation in 58.5%. Using an outcome prediction score specific for acute renal failure, the predicted risk of death was 66%. Actual mortality was 40% (p = 0.003). Using multivariate logistic regression analysis and neural network analysis, patient outcome could be predicted with good levels of accuracy (receiver operating characteristic 0.89 and 0.9, respectively).

CONCLUSIONS

Early and aggressive CVVH is associated with better than predicted survival in severe acute renal failure after cardiac operations. Using readily available clinical data, the outcome of such patients can be predicted before the implementation of CVVH.

Atrial fibrillation after coronary artery bypass grafting is associated with sympathetic activation

BACKGROUND

We prospectively investigated the role of sympathetic activation in the etiology of atrial fibrillation following coronary artery bypass grafting.

METHODS

Continuous ambulatory monitoring was performed for 80 hours in 131 patients after coronary artery bypass grafting. Right atrial plasma norepinephrine levels were assessed preoperatively and every 4 hours for 48 hours postoperatively.

RESULTS

Of the 131 patients, 50% (65) had development of atrial fibrillation and 36% (47) required treatment. Onset of atrial fibrillation was preceded by a significant increase in sinus rate and atrial ectopic activity. On multivariate logistic regression, elevated mean postoperative norepinephrine levels (5.78 +/- 2.83 versus 3.57 +/- 1.31 nmol/L; p < 0.0001), increased age (68.9 +/- 5.7 versus 63.8 +/- 8.7 years; p = 0.02), and decreased postoperative magnesium levels (0.79 +/- 0.09 versus 0.83 +/- 0.10 mmol/L; p = 0.02) were independently associated with the occurrence of atrial fibrillation.

CONCLUSIONS

Elevated norepinephrine levels suggest that sympathetic activation may be important in the pathogenesis of atrial fibrillation after coronary artery bypass grafting, and this underlines the importance of beta-adrenoceptor blockade as prophylaxis.

Adverse incident reporting in intensive care

This prospective, observational, anonymous incident reporting study aimed to identify and correct factors leading to reduced patient safety in intensive care. An incident was any event which caused or had the potential to cause harm to the patient, but included problems in policy or procedure. Reports were discussed at monthly meetings. Of 390 incidents, 106 occasioned "actual" harm and 284 "potential" harm. There was one death, 86 severe complications and 88 complications of minor severity. Most were transient but the effects of 24 lasted up to a week. Most incidents affected cardiovascular and respiratory systems. Incident categories involved drugs, equipment, management or procedures. Incident causes were knowledge-based, rule-based, technical, slip/lapse, no error or unclassifiable. The study has identified some human and equipment performance problems in our intensive care unit. Correction of these should lead to a reduction in the future incidence of those events and hence an increased level of patient safety.

Haemodynamic, renal and hormonal responses to enalkiren in four patients with post-surgical oliguria

1. The haemodynamic and hormonal responses of four patients with acute post-surgical oliguria (urine output < 0.5 mL/kg per h) were measured in response to the renin inhibitor enalkiren. Enalkiren was infused at 0.01 up to 0.1 mg/kg per h for up to 4 h. 2. Enalkiren infusion was associated with a progressive fall in blood pressure, clinically significant in three of the four patients. Systemic vascular resistance fell in proportion to blood pressure fall. Cardiac output and pulse rate remained unchanged. Effective renal plasma flow rose in all four cases (236 +/- 19 to 327 +/- 38). There was no change in urine flow rate, or urinary sodium excretion. 3. Plasma renin activity (ng angiotensin I/mL per h) fell from 1.9 +/- 0.5 to 0.02 +/- 0.01 (P < 0.04), plasma angiotensin II (pg/mL) fell from 104 +/- 93 to 7.7 +/- 1.5, and plasma aldosterone (ng/dL) fell from 32 +/- 8 to 21 +/- 9 (P = 0.03) at the highest infusion dose. 4. Enalkiren inhibited plasma renin activity with reduced plasma angiotensin II and aldosterone concentrations. This was associated with vasodilation, reduced blood pressure and maintained cardiac output. There was no beneficial effect on renal function in these patients with post-surgical oliguria.