External validation of the ISARIC 4C Mortality Score to predict in-hospital mortality among patients with COVID-19 in a Canadian intensive care unit: a single-centre historical cohort study

PURPOSE

With uncertain prognostic utility of existing predictive scoring systems for COVID-19-related illness, the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) 4C Mortality Score was developed by the International Severe Acute Respiratory and Emerging Infection Consortium as a COVID-19 mortality prediction tool. We sought to externally validate this score among critically ill patients admitted to an intensive care unit (ICU) with COVID-19 and compare its discrimination characteristics to that of the Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores.

METHODS

We enrolled all consecutive patients admitted with COVID-19-associated respiratory failure between 5 March 2020 and 5 March 2022 to our university-affiliated and intensivist-staffed ICU (Jewish General Hospital, Montreal, QC, Canada). After data abstraction, our primary outcome of in-hospital mortality was evaluated with an objective of determining the discriminative properties of the ISARIC 4C Mortality Score, using the area under the curve of a logistic regression model.

RESULTS

A total of 429 patients were included, 102 (23.8%) of whom died in hospital. The receiver operator curve of the ISARIC 4C Mortality Score had an area under the curve of 0.762 (95% confidence interval [CI], 0.717 to 0.811), whereas those of the SOFA and APACHE II scores were 0.705 (95% CI, 0.648 to 0.761) and 0.722 (95% CI, 0.667 to 0.777), respectively.

CONCLUSIONS

The ISARIC 4C Mortality Score is a tool that had a good predictive performance for in-hospital mortality in a cohort of patients with COVID-19 admitted to an ICU for respiratory failure. Our results suggest a good external validity of the 4C score when applied to a more severely ill population.

High-flow nasal oxygen as first-line therapy for COVID-19-associated hypoxemic respiratory failure: a single-centre historical cohort study

PURPOSE

The optimal noninvasive modality for oxygenation support in COVID-19-associated hypoxemic respiratory failure and its association with healthcare worker infection remain uncertain. We report here our experience using high-flow nasal oxygen (HFNO) as the primary support mode for patients with COVID-19 in our institution.

METHODS

We conducted a single-centre historical cohort study of all COVID-19 patients treated with HFNO for at least two hours in our university-affiliated and intensivist-staffed intensive care unit (Jewish General Hospital, Montreal, QC, Canada) between 27 August 2020 and 30 April 2021. We report their clinical characteristics and outcomes. Healthcare workers in our unit cared for these patients in single negative pressure rooms wearing KN95 or fit-tested N95 masks; they underwent mandatory symptomatic screening for COVID-19 infection, as well as a period of asymptomatic screening.

RESULTS

One hundred and forty-two patients were analysed, with a median [interquartile range (IQR)] age of 66 [59-73] yr; 71% were male. Patients had a median [IQR] Sequential Organ Failure Assessment Score of 3 [2-3], median [IQR] oxygen saturation by pulse oximetry/fraction of inspired oxygen ratio of 120 [94-164], and a median [IQR] 4C score (a COVID-19-specific mortality score) of 12 [10-14]. Endotracheal intubation occurred in 48/142 (34%) patients, and overall hospital mortality was 16%. Barotrauma occurred in 21/142 (15%) patients. Among 27 symptomatic and 139 asymptomatic screening tests, there were no cases of HFNO-related COVID-19 transmission to healthcare workers.

CONCLUSION

Our experience indicates that HFNO is an effective first-line therapy for hypoxemic respiratory failure in COVID-19 patients, and can be safely used without significant discernable infection risk to healthcare workers.

Outcomes and clinical practice in patients with COVID-19 admitted to the intensive care unit in Montréal, Canada: a descriptive analysis

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic is responsible for millions of infections worldwide, and a substantial number of these patients will be admitted to the intensive care unit (ICU). Our objective was to describe the characteristics, outcomes and management of critically ill patients with COVID-19 pneumonia at a single designated pandemic centre in Montréal, Canada.

METHODS

A descriptive analysis was performed on consecutive critically ill patients with COVID-19 pneumonia admitted to the ICU at the Jewish General Hospital, a designated pandemic centre in Montréal, between Mar. 5 and May 21, 2020. Complete follow-up data corresponding to death or discharge from hospital health records were included to Aug. 4, 2020. We summarized baseline characteristics, management and outcomes, including mortality.

RESULTS

A total of 106 patients were included in this study. Twenty-one patients (19.8%) died during their hospital stay, and the ICU mortality was 17.0% (18/106); all patients were discharged home or died, except for 4 patients (2 awaiting a rehabilitation bed and 2 awaiting long-term care). Twelve of 65 patients (18.5%) requiring mechanical ventilation died. Prone positioning was used in 29 patients (27.4%), including in 10 patients who were spontaneously breathing; no patient was placed on extracorporeal membrane oxygenation. High-flow nasal cannula was used in 51 patients (48.1%). Acute kidney injury was the most common complication, seen in 20 patients (18.9%), and 12 patients (11.3%) required renal replacement therapy. A total of 53 patients (50.0%) received corticosteroids.

INTERPRETATION

Our cohort of critically ill patients with COVID-19 had lower mortality than that previously described in other jurisdictions. These findings may help guide critical care decision-making in similar health care systems in further COVID-19 surges.

Antihypertensive agents acting on the renin-angiotensin system and the risk of sepsis

AIMS

In response to safety concerns from two large randomized controlled trials, we investigated whether the use of telmisartan, an angiotensin receptor blocker (ARB), ARBs as a class and angiotensin-converting enzyme inhibitors (ACEIs) increase the risk of sepsis, sepsis-associated mortality and renal failure in hypertensive patients.

METHODS

We performed a nested case-control study from a retrospective cohort of adults with hypertension from the UK General Practice Research Database diagnosed between 1 January 2000 and 30 June 2009. All subjects hospitalized with sepsis during follow-up were matched for age, sex, practice and duration of follow-up with 10 control subjects. Exposure was defined as current use of antihypertensive drugs.

RESULTS

From the cohort of 550 436 hypertensive patients, 1965 were hospitalized with sepsis during follow-up (rate 6.9 per 10 000 per year), of whom 824 died and 346 developed acute renal failure within 30 days. Compared with use of β-blockers, calcium-channel blockers or diuretics, use of ARBs, including telmisartan, was not associated with an elevated risk of sepsis (relative risk 1.09; 95% confidence interval 0.83-1.43); but use ACEIs was (relative risk 1.65; 95% confidence interval 1.42-1.93). Users of ARBs, β-blockers, calcium-channel blockers or diuretics, but not users of ACEIs, had lower rates of hospitalization for sepsis compared with untreated hypertensive patients. Findings were similar for sepsis-related 30 day mortality and renal failure.

CONCLUSIONS

Hypertensive patients treated with ARBs, including telmisartan, do not appear to be at increased risk of sepsis or sepsis-related 30 day mortality or renal failure. On the contrary, users of ACEIs may have an increased risk.

Antimicrobial therapeutic determinants of outcomes from septic shock among patients with cirrhosis

It is unclear whether practice-related aspects of antimicrobial therapy contribute to the high mortality from septic shock among patients with cirrhosis. We examined the relationship between aspects of initial empiric antimicrobial therapy and mortality in patients with cirrhosis and septic shock. This was a nested cohort study within a large retrospective database of septic shock from 28 medical centers in Canada, the United States, and Saudi Arabia by the Cooperative Antimicrobial Therapy of Septic Shock Database Research Group between 1996 and 2008. We examined the impact of initial empiric antimicrobial therapeutic variables on the hospital mortality of patients with cirrhosis and septic shock. Among 635 patients with cirrhosis and septic shock, the hospital mortality was 75.6%. Inappropriate initial empiric antimicrobial therapy was administered in 155 (24.4%) patients. The median time to appropriate antimicrobial administration was 7.3 hours (interquartile range, 3.2-18.3 hours). The use of inappropriate initial antimicrobials was associated with increased mortality (adjusted odds ratio [aOR], 9.5; 95% confidence interval [CI], 4.3-20.7], as was the delay in appropriate antimicrobials (aOR for each 1 hour increase, 1.1; 95% CI, 1.1-1.2). Among patients with eligible bacterial septic shock, a single rather than two or more appropriate antimicrobials was used in 226 (72.9%) patients and was also associated with higher mortality (aOR, 1.8; 95% CI, 1.0-3.3). These findings were consistent across various clinically relevant subgroups.

CONCLUSION

In patients with cirrhosis and septic shock, inappropriate and delayed appropriate initial empiric antimicrobial therapy is associated with increased mortality. Monotherapy of bacterial septic shock is also associated with increased mortality. The process of selection and implementation of empiric antimicrobial therapy in this high-risk group should be restructured.

Non-steroidal anti-inflammatory drugs and the risk of Clostridium difficile-associated disease

AIM

Several case reports have linked diclofenac, a non-steroidal anti-inflammatory drug (NSAID), with Clostridium difficile associated disease (CDAD). We assessed whether NSAID use in general, and diclofenac use in particular, is associated with an increased risk of CDAD.

METHODS

We used the United Kingdom's General Practice Research Database (GPRD) to conduct a population-based case-control study. All cases of CDAD occurring between 1994 and 2005 were identified and were matched to 10 controls each. Conditional logistic regression was used to estimate the odds ratio of CDAD associated with current NSAID use, adjusting for covariates.

RESULTS

We identified 1360 CDAD cases and 13 072 controls. We found an increased risk of CDAD associated with diclofenac (adjusted odds ratio (RR) 1.35, 95% confidence interval (CI) 1.10, 1.67). We did not observe an increased risk of CDAD with use of any other NSAID. No dose-response for diclofenac exposure was found. When we analyzed only patients who were not hospitalized in the year before the index date, we found diclofenac to have a similar effect on CDAD risk (adjusted RR 1.43, 95% CI 1.11, 1.84).

CONCLUSION

Diclofenac use is associated with a modest increase in the risk of CDAD. In patients at risk of CDAD, other NSAIDs could be prescribed.

The relationship between inotrope exposure, six-hour postoperative physiological variables, hospital mortality and renal dysfunction in patients undergoing cardiac surgery

Introduction

Acute haemodynamic complications are common after cardiac surgery and optimal perioperative use of inotropic agents, typically guided by haemodynamic variables, remains controversial. The aim of this study was to examine the relationship of inotrope use to hospital mortality and renal dysfunction.

Material and methods

A retrospective cohort study of 1,326 cardiac surgery patients was carried out at two university-affiliated ICUs. Multivariable logistic regression analysis and propensity matching were performed to evaluate whether inotrope exposure was independently associated with mortality and renal dysfunction.

Results

Patients exposed to inotropes had a higher mortality rate than those not exposed. After adjusting for differences in Parsonnet score, left ventricular ejection fraction, perioperative intraaortic balloon pump use, bypass time, reoperation and cardiac index, inotrope exposure appeared to be independently associated with increased hospital mortality (adjusted odds ratio (OR) 2.3, 95% confidence interval (95% CI) 1.2 to 4.5) and renal dysfunction (adjusted OR 2.7, 95% CI 1.5 to 4.6). A propensity score-matched analysis similarly demonstrated that death and renal dysfunction were significantly more likely to occur in patients exposed to inotropes (P = 0.01).

Conclusions

Postoperative inotrope exposure was independently associated with worse outcomes in this cohort study. Further research is needed to better elucidate the appropriate use of inotropes in cardiac surgery.

Gene expression profiling in the developing rat brain exposed to ketamine

Ketamine, a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, is associated with accelerated neuronal apoptosis in the developing rodent brain. In this study, postnatal day (PND) 7 rats were treated with 20 mg/kg ketamine or saline in six successive doses (s.c.) at 2-h intervals. Brain frontal cortical areas were collected 6 h after the last dose and RNA isolated and hybridized to Illumina Rat Ref-12 Expression BeadChips containing 22,226 probes. Many of the differentially expressed genes were associated with cell death or differentiation and receptor activity. Ingenuity Pathway Analysis software identified perturbations in NMDA-type glutamate, GABA and dopamine receptor signaling. Quantitative polymerase chain reaction (Q-PCR) confirmed that NMDA receptor subunits were significantly up-regulated. Up-regulation of NMDA receptor mRNA signaling was further confirmed by in situ hybridization. These observations support our working hypothesis that prolonged ketamine exposure produces up-regulation of NMDA receptors and subsequent over-stimulation of the glutamatergic system by endogenous glutamate, triggering enhanced apoptosis in developing neurons.

Risk factors for mortality following emergency colectomy for fulminant Clostridium difficile infection

PURPOSE

This study evaluated risk factors for mortality after emergency colectomy for fulminant Clostridium difficile infection.

METHODS

Retrospective study of 130 cases of Clostridium difficile infection that required a colectomy between 1994 and 2007 in four hospitals of Quebec, Canada. Primary outcome was 30-day mortality.

RESULTS

Twenty-five cases underwent colectomy in 1994 to 2002, 41 in 2003, 40 in 2004, and 24 in 2005 to 2007. Common indications were septic shock (41 percent) and nonresponse to medical treatment (39 percent). Overall, 30-day mortality was 37 percent. Mortality increased with age but was not influenced by comorbidities burden. Mortality correlated with preoperative lactate (< or =2.1 mmol/L: 26 percent; 2.2-4.9 mmol/L: 52 percent; > or =5.0 mmol/L: 75 percent, P < 0.001), leukocytosis (<20.0 x 10(9)/L: 32 percent; 20.0-49.9 x 10(9)/L: 33 percent; > or =50.0 x 10(9)/L: 73 percent, P = 0.008), albumin (> or =25 g/L: 19 percent; 15-24 g/L: 38 percent; <15 g/L: 52 percent, P = 0.04) and renal failure. In multivariate analysis, risk factors for mortality were age (per year, adjusted odds ratio: 1.03, 95 percent confidence interval: 1.00-1.06), preoperative lactate greater than or equal to 5.0 mmol/L (adjusted odds ratio: 10.32, 95 percent confidence interval: 2.59-41.1), leukocytosis greater than or equal to 50.0 x10(9)/L (adjusted odds ratio: 3.68, 95 percent confidence interval: 0.92-14.8) and albumin less than 15 g/L (adjusted odds ratio, 6.57, 95 percent confidence interval: 1.31-33.1).

CONCLUSIONS

Incidence of Clostridium difficile infection-related emergency colectomies increased 20-fold during the epidemic. Postoperative mortality can be predicted by simple laboratory parameters. Three-fourths of patients with leukocytosis greater or equal to 50.0 x10(9)/L or lactate greater or equal to 5.0 mmol/L died. When possible, emergency colectomy should be performed earlier.

Acute kidney injury in septic shock: clinical outcomes and impact of duration of hypotension prior to initiation of antimicrobial therapy

OBJECTIVE

To describe the incidence and outcomes associated with early acute kidney injury (AKI) in septic shock and explore the association between duration from hypotension onset to effective antimicrobial therapy and AKI.

DESIGN

Retrospective cohort study.

SUBJECTS

A total of 4,532 adult patients with septic shock from 1989 to 2005.

SETTING

Intensive care units of 22 academic and community hospitals in Canada, the United States and Saudi Arabia.

MEASUREMENTS AND MAIN RESULTS

In total, 64.4% of patients with septic shock developed early AKI (i.e., within 24 h after onset of hypotension). By RIFLE criteria, 16.3% had risk, 29.4% had injury and 18.7% had failure. AKI patients were older, more likely female, with more co-morbid disease and greater severity of illness. Of 3,373 patients (74.4%) with hypotension prior to receiving effective antimicrobial therapy, the median (IQR) time from hypotension onset to antimicrobial therapy was 5.5 h (2.0-13.3). Patients with AKI were more likely to have longer delays to receiving antimicrobial therapy compared to those with no AKI [6.0 (2.3-15.3) h for AKI vs. 4.3 (1.5-10.8) h for no AKI, P < 0.0001). A longer duration to antimicrobial therapy was also associated an increase in odds of AKI [odds ratio (OR) 1.14, 95% CI 1.10-1.20, P < 0.001, per hour (log-transformed) delay]. AKI was associated with significantly higher odds of death in both ICU (OR 1.73, 95% CI 1.60-1.9, P < 0.0001) and hospital (OR 1.62, 95% CI, 1.5-1.7, P < 0.0001). By Cox proportional hazards analysis, including propensity score-adjustment, each RIFLE category was independently associated with a greater hazard ratio for death (risk 1.31; injury 1.45; failure 1.56).

CONCLUSION

Early AKI is common in septic shock. Delays to appropriate antimicrobial therapy may contribute to significant increases in the incidence of AKI. Survival was considerably lower for septic shock associated with early AKI, with increasing severity of AKI, and with increasing delays to appropriate antimicrobial therapy.

Patterns of antibiotic use and risk of hospital admission because of Clostridium difficile infection

BACKGROUND

Previous observations have indicated that infection with Clostridium difficile occurs almost exclusively after exposure to antibiotics, but more recent observations have suggested that prior antibiotic exposure may be less frequent among cases of community-acquired disease.

METHODS

We used 2 linked health databases to perform a matched, nested case-control study of elderly patients admitted to hospital with community-acquired C. difficile infection. For each of 836 cases among people 65 years of age or older, we selected 10 controls. We determined the proportion of cases that occurred without prior antibiotic exposure and estimated the risk related to exposure to different antibiotics and the duration of increased risk.

RESULTS

Of the 836 cases, 442 (52.9%) had no exposure to antibiotics in the 45-day period before the index date, and 382 (45.7%) had no exposure in the 90-day period before the index date. Antibiotic exposure was associated with a rate ratio (RR) of 10.6 (95% confidence interval [CI] 8.9-12.8). Clindamycin (RR 31.8, 95% CI 17.6-57.6), cephalosporins (RR 14.9, 95% CI 10.9-20.3) and gatifloxacin (RR 16.7, 95% CI 8.3-33.6) were associated with the highest risk. The RR for C. difficile infection associated with antibiotic exposure declined from 15.4 (95% CI 12.2-19.3) by about 20 days after exposure to 3.2 (95% CI 2.0-5.0) after 45 days. Use of a proton pump inhibitor was associated with increased risk (RR 1.6, 95% CI 1.3-2.0), as were concurrent diagnoses of inflammatory bowel disease (RR 4.1, 95% CI 2.6-6.6), irritable bowel syndrome (RR 3.4, 95% CI 2.3-5.0) and renal failure (RR 1.7, 95% CI 1.2-2.2).

INTERPRETATION

Community-acquired C. difficile infection occurred in a substantial proportion of individuals with no recent exposure to antibiotics. Among patients who had been exposed to antibiotics, the risk declined markedly by 45 days after discontinuation of use.

Patterns of antibiotic use and risk of hospital admission because of Clostridium difficile infection

BACKGROUND

Previous observations have indicated that infection with Clostridium difficile occurs almost exclusively after exposure to antibiotics, but more recent observations have suggested that prior antibiotic exposure may be less frequent among cases of community-acquired disease.

METHODS

We used 2 linked health databases to perform a matched, nested case-control study of elderly patients admitted to hospital with community-acquired C. difficile infection. For each of 836 cases among people 65 years of age or older, we selected 10 controls. We determined the proportion of cases that occurred without prior antibiotic exposure and estimated the risk related to exposure to different antibiotics and the duration of increased risk.

RESULTS

Of the 836 cases, 442 (52.9%) had no exposure to antibiotics in the 45-day period before the index date, and 382 (45.7%) had no exposure in the 90-day period before the index date. Antibiotic exposure was associated with a rate ratio (RR) of 10.6 (95% confidence interval [CI] 8.9-12.8). Clindamycin (RR 31.8, 95% CI 17.6-57.6), cephalosporins (RR 14.9, 95% CI 10.9-20.3) and gatifloxacin (RR 16.7, 95% CI 8.3-33.6) were associated with the highest risk. The RR for C. difficile infection associated with antibiotic exposure declined from 15.4 (95% CI 12.2-19.3) by about 20 days after exposure to 3.2 (95% CI 2.0-5.0) after 45 days. Use of a proton pump inhibitor was associated with increased risk (RR 1.6, 95% CI 1.3-2.0), as were concurrent diagnoses of inflammatory bowel disease (RR 4.1, 95% CI 2.6-6.6), irritable bowel syndrome (RR 3.4, 95% CI 2.3-5.0) and renal failure (RR 1.7, 95% CI 1.2-2.2).

INTERPRETATION

Community-acquired C. difficile infection occurred in a substantial proportion of individuals with no recent exposure to antibiotics. Among patients who had been exposed to antibiotics, the risk declined markedly by 45 days after discontinuation of use.

Is over-use of proton pump inhibitors fuelling the current epidemic of Clostridium difficile-associated diarrhoea?

Many developed countries have seen an increase in cases of Clostridium difficile-associated diarrhoea (CDAD) in recent years. This has occurred despite heightened awareness of the risks of broad-spectrum antibiotics, overall reduction in antibiotic use and increased focus on hospital hygiene. Some of the increase is due to the introduction of new hypervirulent strains, but it predates the description of these. The epidemic coincides with increased use of proton pump inhibitors (PPIs), much of which is inappropriate according to UK and other national guidelines. Gastric acid is a key host defence against other gastrointestinal infections and epidemiological and animal studies have demonstrated a positive association between incident CDAD and PPI use. An association with recurrence of CDAD after initially successful treatment has also been found. Vegetative C. difficile cells are rapidly killed at normal gastric pH, but survive at the pH found in patients taking PPI. It has recently been shown that vegetative organisms survive long enough on moist surfaces for transmission between patients to occur. We conclude that restricting PPI use to patients with an appropriate indication would reduce unnecessary expenditure on these agents, and might be an additional means of controlling the current epidemic of CDAD.

Antimicrobial drugs and community-acquired methicillin-resistant Staphylococcus aureus, United Kingdom

We report results of a case-control study of the association between receipt of antimicrobial agents and diagnosis of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) in the United Kingdom. Eligible adults, selected from the General Practice Research Database, had no previous diagnosis of MRSA, no hospitalization in the past 2 years, and > or = 2 years of follow-up recorded in the database. For 2000-2004, we identified 1,981 MRSA case-patients and 19,779 matched control-patients. The odds ratios (ORs) and 95% confidence intervals (CIs) of MRSA diagnosis for patients who were prescribed 1, 2-3, or > or = 4 antimicrobial drugs were 1.57 (CI 1.36-1.80), 2.46 (CI 2.15-2.83), and 6.24 (CI 5.43-7.17), respectively. Risk for community-acquired MRSA increased with number of antimicrobial drug prescriptions, appeared to vary according to antimicrobial drug classes prescribed the previous year, and was highest for quinolones (OR 3.37, CI 2.80-4.09) and macrolides (OR 2.50, CI 2.14-2.91).

Antimicrobial drugs and community-acquired Clostridium difficile-associated disease, UK

In a population-based case-control study of community-acquired Clostridium difficile–associated disease (CDAD), we matched 1,233 cases to 12,330 controls. CDAD risk increased 3-fold with use of any antimicrobial agent and 6-fold with use of fluoroquinolones. Prior use of antimicrobial agent did not affect risk for CDAD after 6 months.

Is there a role for mask continuous positive airway pressure in acute respiratory failure due to COPD? Lessons from a retrospective audit of 3 different cohorts

Exacerbations of COPD that result in acute respiratory failure requiring intubation and mechanical ventilation have high morbidity and mortality. This study is a retrospective observational study that compared the outcomes of 237 patients with COPD and acute respiratory failure requiring intensive care unit (ICU) admission according to modality of initial therapy: mask continuous positive airway pressure (CPAP), medical therapy, or intubation. Of the patients treated with CPAP initially, only 16% failed and required intubation compared with 62% of those treated medically (p=0.001). The median length of ICU stay was 5 days in those treated with CPAP, compared with 7 days for those medically treated, and 8.5 days for intubated patients (p=0.001). When compared with mask CPAP, and after adjusting for potentially confounding differences, mortality was significantly higher if patients were initially intubated (adjusted odds ratios [OR] 15.7; 95% confidence interval [CI] 4.2, 59) or given medical therapy (OR 5.1; CI 1.2, 20.8). In COPD patients with acute respiratory failure, initial treatment with mask CPAP was associated with significantly better outcomes than other treatment modalities, even after adjusting for potentially confounding differences in disease severity.

Proton pump inhibitor use and risk of community-acquired Clostridium difficile-associated disease defined by prescription for oral vancomycin therapy

BACKGROUND

The association between the use of proton pump inhibitors and the risk of Clostridium difficile-associated disease (CDAD) is controversial. In this study we re-examined a previously reported association between the use of proton pump inhibitors and the development of community-acquired CDAD, this time using an alternative case definition of the disease.

METHODS

We performed a case-control study of community-acquired CDAD using a United Kingdom clinical research database. Patients receiving oral vancomycin therapy were identified as having CDAD, the only indication for this drug. Each case subject was matched with up to 10 control subjects. Neither the cases nor the controls had been admitted to hospital in the year before the date of the vancomycin prescription (index date). Conditional logistic regression analysis was used to adjust for key covariates.

RESULTS

We identified 317 cases of community-acquired CDAD treated with oral vancomycin therapy and 3167 matched control subjects. Exposure to a proton pump inhibitor in the 90 days before the index date was associated with an increased risk of CDAD (odds ratio [OR] 3.5, 95% confidence interval [CI] 2.3-5.2). Antibiotic exposure in the 90 days before the index date was also a significant risk factor for community-acquired CDAD (OR 8.2, 95% CI 6.1- 11.0), even though 45% of the case subjects had not received a prescription for an antibiotic during that period. Certain comorbidities, in particular renal failure, inflammatory bowel disease and malignant disease, as well as prior methicillin-resistant Staphylococcus aureus infection, were also associated with an increased risk.

INTERPRETATION

Proton pump inhibitor use was associated with an increased risk of community-acquired CDAD, when cases were defined by receipt of prescription for oral vancomycin therapy. Prior antibiotic exposure was also a significant risk factor, but a significant proportion of the patients with community-acquired CDAD had no such exposure.

Use of gastric acid-suppressive agents and the risk of community-acquired Clostridium difficile-associated disease

CONTEXT

Recent reports suggest an increasing occurrence and severity of Clostridium difficile-associated disease. We assessed whether the use of gastric acid-suppressive agents is associated with an increased risk in the community.

OBJECTIVE

To determine whether the use of gastric acid-suppressive agents increases the risk of C difficile-associated disease in a community population.

DESIGN, SETTING, AND PATIENTS

We conducted 2 population-based case-control studies using the United Kingdom General Practice Research Database (GPRD). In the first study, we identified all 1672 cases of C difficile recorded between 1994 and 2004 among all patients registered for at least 2 years in each practice. Each case was matched to 10 controls on calendar time and the general practice. In the second study, a subset of these cases defined as community-acquired, that is, not hospitalized in the prior year, were matched on practice and age with controls also not hospitalized in the prior year.

MAIN OUTCOME MEASURES

The incidence of C difficile and risk associated with gastric acid-suppressive agent use.

RESULTS

The incidence of C difficile in patients diagnosed by their general practitioners in the General Practice Research Database increased from less than 1 case per 100,000 in 1994 to 22 per 100,000 in 2004. The adjusted rate ratio of C difficile-associated disease with current use of proton pump inhibitors was 2.9 (95% confidence interval [CI], 2.4-3.4) and with H2-receptor antagonists the rate ratio was 2.0 (95% CI, 1.6-2.7). An elevated rate was also found with the use of nonsteroidal anti-inflammatory drugs (rate ratio, 1.3; 95% CI, 1.2-1.5).

CONCLUSIONS

The use of acid-suppressive therapy, particularly proton pump inhibitors, is associated with an increased risk of community-acquired C difficile. The unexpected increase in risk with nonsteroidal anti-inflammatory drug use should be investigated further.

Abnormal neuronal metabolism and storage in mucopolysaccharidosis type VI (Maroteaux-Lamy) disease

Mucopolysaccharidosis (MPS) type VI, also known as Maroteaux-Lamy disease, is an inherited disorder of glycosaminoglycan catabolism caused by deficient activity of the lysosomal hydrolase, N-acetylgalactosamine 4-sulphatase (4S). A variety of prominent visceral and skeletal defects are characteristic, but primary neurological involvement has generally been considered absent. We report here that the feline model of MPS VI exhibits abnormal lysosomal storage in occasional neurones and glia distributed throughout the cerebral cortex. Abnormal lysosomal inclusions were pleiomorphic with some resembling zebra bodies and dense core inclusions typical of other MPS diseases or the membranous storage bodies characteristic of the gangliosidoses. Pyramidal neurones were shown to contain abnormal amounts of GM2 and GM3 gangliosides by immunocytochemical staining and unesterified cholesterol by histochemical (filipin) staining. Further, Golgi staining of pyramidal neurones revealed that some possessed ectopic axon hillock neurites and meganeurites similar to those described in Tay-Sachs and other neuronal storage diseases with ganglioside storage. Some animals evaluated in this study also received allogeneic bone marrow transplants, but no significant differences in neuronal storage were noted between treated and untreated individuals. These studies demonstrate that deficiency of 4S activity can lead to metabolic abnormalities in the neurones of central nervous system in cats, and that these changes may not be readily amenable to correction by bone marrow transplantation. Given the close pathological and biochemical similarities between feline and human MPS VI, it is conceivable that children with this disease have similar neuronal involvement.

Invasive aspergillosis in patients with chronic obstructive pulmonary diseases

OBJECTIVES

To determine the outcomes, and clinical and therapeutic factors associated with the development of invasive pulmonary aspergillosis (IPA) in patients with obstructive pulmonary diseases.

DESIGN

A case control study examining patients who developed IPA while hospitalized, and controls who were matched by year of hospitalization and type of obstructive lung disease.

SETTING

A tertiary care university-affiliated respiratory hospital.

PATIENTS

Twelve patients were identified who had developed nosocomial IPA. Each case was compared with four control patients: two with and two without Aspergillus colonization.

RESULTS

Patients and control patients had similar demographic characteristics, comorbid illnesses and severity of underlying pulmonary disease. All cases required admission to the intensive care unit and eight patients (67%) died, whereas only 17% of control patients required admission to the intensive care unit and 7% died. The patients with IPA received significantly higher daily doses of corticosteroids (median 106 mg of prednisone or equivalent for 18 days) and more broad-spectrum antibiotics (median three antibiotics for 13 days) in hospital before the development of aspergillosis compared with the control patients (median 44 mg for 14 days, and 1.5 antibiotics for nine days, respectively). Among the control patients, those with Aspergillus colonization were more likely to have received corticosteroid therapy and broad-spectrum antibiotics during and in the month preceding the index hospitalization, although the hospital course was not different.

CONCLUSIONS

IPA, although rare in patients with chronic obstructive lung diseases, was associated with high doses of corticosteroids and multiple broad-spectrum antibiotics. More judicious use of antibiotics and avoidance of prolonged high-dose corticosteroids may help prevent occurrences of IPA with its attendant serious morbidity and high mortality.

Hemodilution and surgical hemostasis contribute significantly to transfusion requirements in patients undergoing coronary artery bypass

OBJECTIVE

We sought to determine the incidence of and risk factors for the development of low intraoperative hematocrit levels and of excessive postoperative bleeding in patients undergoing coronary artery bypass grafting, whether the risk factors are the same, and their effect on blood product transfusions.

METHODS

We performed a prospective cohort study of 613 adult patients who underwent coronary artery bypass grafting in 3 tertiary, university-affiliated hospitals during the period from October 1, 2000, to March 31, 2001.

RESULTS

Low intraoperative hematocrit levels (<19%) were found in 131 (24%) patients who had operations performed with extracorporeal circulation compared with in 3 (4%) patients with operations performed off pump. In multivariate analysis this was associated with older age, female sex, lower preoperative hemoglobin levels, lower body surface area, longer duration on bypass, and use of higher total volumes with more hydroxyethyl starch in the circuit. Low intraoperative hematocrit levels did not predict excessive postoperative hemorrhage (>1 L of mediastinal drainage in the first 12 hours). This occurred in 26% (n = 140) of patients undergoing on-pump operations and in 25% of patients undergoing off-pump operations and in multivariate analysis was associated with male sex, longer pump times, not receiving aprotinin, and operations performed by certain surgeons but not with total circuit or hydroxyethyl starch volume.

CONCLUSIONS

We observed that the risk factors for the development of a low intraoperative hematocrit level and excessive postoperative bleeding differed. Our results suggest that decreasing these outcomes in patients undergoing cardiac surgery requires a comprehensive approach, including limiting hemodilution, particularly in female subjects with lower preoperative hemoglobin levels, and careful attention to surgical hemostasis.

Risk of Clostridium difficile diarrhea among hospital inpatients prescribed proton pump inhibitors: cohort and case-control studies

BACKGROUND

Antibiotic disruption of the normal intestinal flora is a well-known risk factor for Clostridium difficile-associated diarrhea. Reduced gastric acidity has been suggested as a risk factor, and we hypothesized that proton pump inhibitors, because of their potency, may be an independent risk factor for this problem.

METHODS

For the cohort study we identified from a pharmacy database 1187 inpatients at a Montreal teaching hospital who received antibiotics over a 9-month period beginning in August 2002. We compared patients in this group who had also received a proton pump inhibitor or an H(2) blocker with patients who had not received acid suppressive therapy. Hospital laboratory reports of positive assay results for C. difficile toxin were used to ascertain cases in the cohort. To assess the possibility that proton pump inhibitors were prescribed to patients who were sicker and had other risk factors for C. difficile infection, we did a case-control study at a second Montreal teaching hospital. Cases were defined as patients who were positive for C. difficile toxin and who had a history of diarrhea (n = 94). Control subjects were selected from among patients who had received an antibiotic and were matched to cases by ward, age within 5 years and class of antibiotics (n = 94).

RESULTS

In the cohort study, C. difficile diarrhea developed in 81 (6.8%) of the 1187 patients who received antibiotics while in hospital. In a multivariate analysis, C. difficile diarrhea was significantly associated with use of proton pump inhibitors (adjusted odds ratio [OR] 2.1, 95% confidence interval [CI] 1.2- 3.5), receipt of 3 or more antibiotics (OR 2.1, 95% CI 1.3- 3.4) and admission to a medical ward (OR 4.1, 95% CI 2.3- 7.3). In the case-control study C. difficile diarrhea was associated with female sex (adjusted OR 2.1, 95% CI 1.1-4.0), prior renal failure (adjusted OR 4.3, 95% CI 1.5-11.9), hospital admission in the 3 months before the index admission (adjusted OR 2.6, 95% CI 1.4-5.2) and use of proton pump inhibitors (adjusted OR 2.7, 95% CI 1.4-5.2).

INTERPRETATION

Patients in hospital who received proton pump inhibitors were at increased risk of C. difficile diarrhea.

Autotransfusion of Shed Mediastinal Blood *

RATIONALE

After the introduction of autotransfusion of shed mediastinal blood following cardiac surgery, the incidence of mediastinitis increased. The role of autotransfusion in the increased occurrence of this serious complication was examined.

METHODS

Using a case-control design, the preoperative, intraoperative, and postoperative characteristics of 11 patients with mediastinitis were compared to those of 33 randomly selected patients undergoing cardiac surgery between September 1, 2000, and April 15, 2001 (control subjects).

RESULTS

Patients with mediastinitis were significantly more likely to have a body mass index > 30 (unadjusted odds ratio [OR], 9.9; 95% confidence interval [CI], 2.3 to 42.5), to have received antibiotic therapy during the 2 weeks prior to cardiac surgery (OR, 12.0; 95% CI, 1.1 to 131), or to have required re-exploration within 24 h of the original operation (OR, 8.3; 95% CI, 1.8 to 39). Patients with mediastinitis had 3.4 known risk factors for mediastinitis, compared to only 1.4 risk factors per control subject (p = 0.0001), and longer duration of autotransfusion. After adjustment for other risk factors, autotransfusion for > 6 h was significantly associated with the development of mediastinitis (adjusted OR, 11.9; 95% CI, 1.4 to 97.2).

CONCLUSION

Retransfusion of shed mediastinal blood for > 6 h after cardiac surgery was an independent risk factor for mediastinitis.

Re-Evaluation of Acid-Base Prediction Rules in Patients with Chronic Respiratory Acidosis

RATIONALE: The prediction rules for the evaluation of the acid-base status in patients with chronic respiratory acidosis, derived primarily from an experimental canine model, suggest that complete compensation should not occur. This appears to contradict frequent observations of normal or near-normal pH levels in patients with chronic hypercapnia.

METHODS: Linear regression analysis was used to estimate the relationships between arterial pH, bicarbonate and partial pressure of carbon dioxide (PCO2) from 18 separate arterial blood gas measurements in 18 clinically stable outpatients with chronic hypercapnic respiratory failure from chronic obstructive lung disease, and without clinical conditions or medications likely to cause a primary metabolic alkalosis.

RESULTS: The PCO2ranged from 45 mmHg to 77 mmHg, and pH ranged from 7.37 to 7.44. In only three of the arterial blood gas measurements were the pH values lower than 7.38. From the regression equations derived from these measurements, the pH decreased by 0.014 for each 10 mmHg increase in the PCO2, and the bicarbonate level increased by 5.1 mmol/L. These values are quite different from a decrease in pH of 0.03 and an increase in bicarbonate of 3.5 mmol/L predicted using the rules derived from the canine model.

CONCLUSIONS: In patients with chronic stable hypercapnia, acid-base compensatory mechanisms appear to be more effective than would be predicted using the classic rules.

Pediatric sedation for procedures titrated to a desired degree of immobility results in unpredictable depth of sedation

OBJECTIVE

To test the hypothesis that the need to attain immobility during pediatric sedation for procedures determines the depth of sedation, which cannot always be predicted.

DESIGN

A retrospective review of sedation documents of 301 consecutive sedations of pediatric patients undergoing various procedures

SETTING

Division of Critical Care sedation service within a children's hospital.

MEASUREMENTS AND MAIN RESULTS

The medical records and sedation forms of our most recent 301 consecutive sedations were retrospectively reviewed. Based on the data gathered, the patients were categorized according to their achieved level of immobility, their level of consciousness according to the definitions of the American Academy of Pediatrics, the procedures for which sedation was administered, and the sedatives used. A total of 125 males and 89 females received 301 sedations. Their ages ranged from 22 days to 29 years (mean 7 y + 6 y). We recognized four categories of immobility for procedures. In category 1, some motion was allowed during painless and noninvasive procedures to the extent that it did not risk the patient nor hinder the successful performance of the procedures. In category 2, the patients were kept motionless during painless and noninvasive procedures. In category 3, the patients were kept motionless during painful and invasive procedures with the addition of local anesthetic. In category 4, the patients remained motionless throughout their painful or invasive procedure without the use of local anesthetics. There were 32, 10, 156 and 103 sedations in each category, respectively. Conscious sedation (CS) was observed in six sedations (19%) in category 1 of immobility; it was observed in none (0%) in category 2, in 4 sedations (2.6%) in category 3, and in 1 sedation (1%) in category 4. Deep sedation (DS) was noted in 26 category 1 sedations (81%), in 10 category 2 sedations (100%), in 136 category 3 sedations (87%), and in 63 category 4 sedations (61%). General anesthesia (GA) was only observed in categories 3 and 4 in 16 sedations (10%) and 39 sedations (38%), respectively. Intravenous (IV) ketamine, as a single agent or in combination with other agents, was the most frequently used sedative (88%) followed by IV benzodiazepines (64%), propofol (39%), opiates (15%), and barbiturates (5%). A total of 59 (19%) adverse events were encountered during the 301 sedations. In categories 1 and 2, no adverse event (0%) was encountered. In category 3, 19 adverse events took place (32%), and 40 adverse events (68%) (P< 0.05) occurred in category 4.

CONCLUSIONS

Pediatric sedation results in 4 categories of immobility. Complete immobility during painful and invasive procedures is associated with a higher incidence of adverse events. The depth of sedation (ie, CS, DS, or GA) required to achieve each category of immobility is unpredictable and varies from patient to patient. Thus, granting a limited sedation authority (conscious sedation only) to physicians may be of limited practical value.

Delirium in an intensive care unit: a study of risk factors

OBJECTIVES

(1) To establish risk factors for the development of delirium in an intensive care unit (ICU) and (2) to determine the effect of delirium on morbidity, mortality and length of stay.

DESIGN

Prospective study.

SETTING

Sixteen-bed medical/surgical ICU in a university hospital.

PATIENTS

Two hundred and sixteen consecutive patients admitted to the ICU for more than 24 h during 5 months were included in the study.

INTERVENTIONS

Medical history, selected laboratory values, drugs received and factors that may influence patient psychological and emotional well-being were noted. All patients were screened with a delirium scale. A psychiatrist confirmed the diagnosis of delirium. Major complications such as self-extubation and removal of catheters, as well as mortality and length of stay were recorded.

RESULTS

Forty patients (19%) developed delirium; of these, one-third were not agitated. In the multivariate analysis hypertension, smoking history, abnormal bilirubin level, epidural use and morphine were statistically significantly associated with delirium. Traditional factors associated with the development of delirium on general ward patients were not significant in our study. Morbidity (self-extubation and removal of catheters), but not mortality, was clearly increased.

CONCLUSION

Predictive risk factors for the development of delirium in studies outside the ICU may not be applicable to critically ill patients. Delirium is associated with increased morbidity. Awareness of patients at risk may lead to better recognition and earlier intervention.

Intensive Care Delirium Screening Checklist: evaluation of a new screening tool

OBJECTIVE

Delirium in the intensive care unit is poorly defined. Clinical evaluation is difficult in the setting of unstable, often intubated patients. A screening tool may improve the detection of delirium.

METHOD

We created a screening checklist of eight items based on DSM criteria and features of delirium: altered level of consciousness, inattention, disorientation, hallucination or delusion, psychomotor agitation or retardation, inappropriate mood or speech, sleep/wake cycle disturbance, and symptom fluctuation. During 3 months, all patients admitted to a busy medical/surgical intensive care unit were evaluated, and the scale score was compared to a psychiatric evaluation.

RESULTS

In 93 patients studied, 15 developed delirium. Fourteen (93%) of them had a score of 4 points or more. This score was also present in 15 (19%) of patients without delirium, 14 of whom had a known psychiatric illness, dementia, a structural neurological abnormality or encephalopathy. A ROC analysis was used to determine the sensitivity and specificity of the screening tool. The area under the ROC curve is 0.9017. Predicted sensitivity is 99% and specificity is 64%.

CONCLUSION

This study suggests that the Intensive Care Delirium Screening Checklist can easily be applied by a clinician or a nurse in a busy critical care setting to screen all patients even when communication is compromised. The tool can be utilized quickly and helps to identify delirious patients. Earlier diagnosis may lead to earlier intervention and better patient care.

Ocular Onchocerca infections in two dogs in western United States

Two dogs, one from California and one from Arizona, were found to have aberrant infections caused by filarial nematodes of the genus Onchocerca. In both cases, the parasites are localized in or near the eye. In one case the worm was located in the cornea and was surgically removed. In the second case, a very marked granulomatous reaction was induced in the retrobulbar space, mimicking an abscess. This eye was enucleated. The worms in both instances were female, and were gravid, i.e. contained microfilariae in utero, indicating that a male worm(s) had been present and mating had occurred. The exact identity of the species of Onchocerca responsible cannot be determined, although the features observed are most like Onchocerca lienalis of cattle. These cases represent the fourth and fifth such cases reported from the US, and are especially interesting because of the unusual location of the worms, the small number of recognized cases, and the similarity to a recent zoonotic human infection.

Automatic control of pressure support mechanical ventilation using fuzzy logic

There is currently no universally accepted approach to weaning patients from mechanical ventilation, but there is clearly a feeling within the medical community that it may be possible to formulate the weaning process algorithmically in some manner. Fuzzy logic seems suited this task because of the way it so naturally represents the subjective human notions employed in much of medical decision-making. The purpose of the present study was to develop a fuzzy logic algorithm for controlling pressure support ventilation in patients in the intensive care unit, utilizing measurements of heart rate, tidal volume, breathing frequency, and arterial oxygen saturation. In this report we describe the fuzzy logic algorithm, and demonstrate its use retrospectively in 13 patients with severe chronic obstructive pulmonary disease, by comparing the decisions made by the algorithm with what actually transpired. The fuzzy logic recommendations agreed with the status quo to within 2 cm H(2)O an average of 76% of the time, and to within 4 cm H(2)O an average of 88% of the time (although in most of these instances no medical decisions were taken as to whether or not to change the level of ventilatory support). We also compared the predictions of our algorithm with those cases in which changes in pressure support level were actually made by an attending physician, and found that the physicians tended to reduce the support level somewhat more aggressively than the algorithm did. We conclude that our fuzzy algorithm has the potential to control the level of pressure support ventilation from ongoing measurements of a patient's vital signs.

Ceftriaxone-related fatal hemolysis in an adolescent with perinatally acquired human immunodeficiency virus infection

A 14-year-old girl with perinatally acquired human immunodeficiency virus infection had fatal intravascular hemolysis after intravenous administration of ceftriaxone. Laboratory studies confirmed the presence of an antibody against ceftriaxone in the serum and on the patient's red blood cells. No evidence of sepsis, glucose-6-phosphate dehydrogenase deficiency or anaphylaxis was found.