The Effect of a Liberal Approach to Glucose Control in Critically Ill Patients with Type 2 Diabetes: A multicenter, parallel-group, open-label, randomized clinical trial

Rationale Blood glucose concentrations affect outcomes in critically ill patients but the optimal target blood glucose range in those with type 2 diabetes is unknown. Objective To evaluate the effects of a 'liberal' approach to targeted blood glucose range during intensive care unit (ICU) admission. Methods This mutlicenter, parallel-group, open-label, randomized clinical trial included 419 adult patients with type 2 diabetes expected to be in the ICU on at least three consecutive days. In the intervention group intravenous insulin was commenced at a blood glucose >252 mg/dL and titrated to a target range of 180 to 252 mg/dL. In the comparator group insulin was commenced at a blood glucose >180 mg/dL and titrated to a target range of 108 to 180 mg/dL. The primary outcome was incident hypoglycemia (<72 mg/dL). Secondary outcomes included glucose metrics and clinical outcomes. Main Results At least one episode of hypoglycemia occurred in 10 of 210 (5%) patients assigned the intervention and 38 of 209 (18%) patients assigned the comparator (incident rate ratio: 0.21 (95% CI, 0.09 to 0.49); P<0.001). Those assigned the intervention had greater blood glucose concentrations (daily mean, minimum, maximum), less glucose variability and less relative hypoglycaemia (P<0.001 for all comparisons). By day 90, 62 of 210 (29.5%) in the intervention and 52 of 209 (24.9%) in the comparator group had died (absolute difference 4.6 percentage points (95%CI, -3.9 to 13.2%); P=0.29). Conclusions A liberal approach to blood glucose targets reduced incident hypoglycemia but did not improve patient-centered outcomes. Clinical trial registration available at www.anzctr.org.au, ID: ACTRN12616001135404.

Study protocol and statistical analysis plan for the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial

BACKGROUND

Contemporary glucose management of intensive care unit (ICU) patients with type 2 diabetes is based on trial data derived predominantly from patients without type 2 diabetes. This is despite the recognition that patients with type 2 diabetes may be relatively more tolerant of hyperglycaemia and more susceptible to hypoglycaemia. It is uncertain whether glucose targets should be more liberal in patients with type 2 diabetes.

OBJECTIVE

To detail the protocol, analysis and reporting plans for a randomised clinical trial - the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial - which will evaluate the risks and benefits of targeting a higher blood glucose range in patients with type 2 diabetes.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTION

A multicentre, parallel group, open label phase 2B randomised controlled clinical trial of 450 critically ill patients with type 2 diabetes. Patients will be randomised 1:1 to liberal blood glucose (target 10.0-14.0 mmol/L) or usual care (target 6.0-10.0 mmol/L).

MAIN OUTCOME MEASURES

The primary endpoint is incident hypoglycaemia (< 4.0 mmol/L) during the study intervention. Secondary endpoints include biochemical and feasibility outcomes.

RESULTS AND CONCLUSION

The study protocol and statistical analysis plan described will delineate conduct and analysis of the trial, such that analytical and reporting bias are minimised.

TRIAL REGISTRATION

This trial has been registered on the Australian New Zealand Clinical Trials Registry (ACTRN No. 12616001135404) and has been endorsed by the Australian and New Zealand Intensive Care Society Clinical Trials Group.

Study protocol and statistical analysis plan for the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial

BACKGROUND: Contemporary glucose management of intensive care unit (ICU) patients with type 2 diabetes is based on trial data derived predominantly from patients without type 2 diabetes. This is despite the recognition that patients with type 2 diabetes may be relatively more tolerant of hyperglycaemia and more susceptible to hypoglycaemia. It is uncertain whether glucose targets should be more liberal in patients with type 2 diabetes. OBJECTIVE: To detail the protocol, analysis and reporting plans for a randomised clinical trial — the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial — which will evaluate the risks and benefits of targeting a higher blood glucose range in patients with type 2 diabetes. DESIGN, SETTING, PARTICIPANTS AND INTERVENTION: A multicentre, parallel group, open label phase 2B randomised controlled clinical trial of 450 critically ill patients with type 2 diabetes. Patients will be randomised 1:1 to liberal blood glucose (target 10.0–14.0 mmol/L) or usual care (target 6.0–10.0 mmol/L). MAIN OUTCOME MEASURES: The primary endpoint is incident hypoglycaemia (< 4.0 mmol/L) during the study intervention. Secondary endpoints include biochemical and feasibility outcomes. RESULTS AND CONCLUSION: The study protocol and statistical analysis plan described will delineate conduct and analysis of the trial, such that analytical and reporting bias are minimised. TRIAL REGISTRATION: This trial has been registered on the Australian New Zealand Clinical Trials Registry (ACTRN No. 12616001135404) and has been endorsed by the Australian and New Zealand Intensive Care Society Clinical Trials Group.

A novel biometric approach to estimating tidal volume

BACKGROUND

Low tidal volume ventilation (LTVV) of 4-8 mL/kg of ideal body weight (IBW) reduces mortality in patients with acute respiratory distress syndrome, and, more recently, it has been recommended as the default therapy for all controlled ventilation. However, adherence to LTVV is poor. Barriers to adherence include not having height measurements taken or IBW calculated during admission. The aim of our project was to develop and validate a simple one step biometric measuring tool to directly estimate tidal volume (V_T) in ventilated patients based on their demispan.

OBJECTIVES

To validate our novel biometric approach for the estimation of V_T in mechanically ventilated patients by demonstrating its accuracy as a simple reliable alternative to IBW derived from measured height.

DESIGN AND SETTING

A simple computer program was written based on regression equations for demispan, height and IBW which used simple substitution to produce a vector graphic scale with markings in millilitres of 6 mL/kg IBW V_T printed onto a paper tape. We performed an observational validation study on ventilated patients after cardiac surgery comparing the V_T derived from demispan measurements using our tape with the V_T based on IBW calculated from pre-operative vertical height.

MAIN OUTCOME MEASURE

We compared compliance with a target V_T ≤ 6.5 mL/kg for V_T derived using our demispan method and with V_T based on IBW calculated from vertical height.

RESULTS

Eighty-two patients were studied. The mean age was 65.7 years (SD, 11.4) and 61 patients (74%) were male. Mean height was 170.4 cm (SD, 9.5) and mean body mass index for the group was 28.6 kg/m² (SD, 5.5). The V_T based on 6 mL/kg IBW estimated by traditional height method and using our biometric tape method correlated well (r = 0.8) and was not statistically different, with a mean difference of -7.5 mL (SEM, 8.8). Bland-Altman plot showed 95% limits of agreement from -64 mL to 79 mL around the mean difference of 7.5 mL, with 4 points (4.9%) outside the limits of agreement. Fifty-one of the initial V_T (62%) were compliant, with a target of ≤ 6.5 mL/kg IBW using volumes determined from measured height, while 66 of the tape volumes (80%) would have been compliant at a target of ≤ 6.5 mL/kg IBW.

CONCLUSION

Estimating V_T using of our biometric one step approach based on demispan correlates well with V_T derived from vertical height. The simplicity of its use and accuracy could lead to improved adherence in a large cohort of patients who currently do not receive the recommended V_T restriction.

Opinions and practices of blood glucose control in critically ill patients with pre-existing type 2 diabetes in Australian and New Zealand intensive care units

BACKGROUND

Approximately 9000 patients with type-2 diabetes mellitus (T2DM) are admitted to an intensive care unit (ICU) in Australia and New Zealand annually. For these patients, recent exploratory data suggest that targeting a more liberal blood glucose range during ICU admission may be safe and potentially beneficial. However, the current approach to blood glucose management of patients with T2DM in Australia and New Zealand ICUs is not well described, and there is uncertainty about clinician equipoise for trials of liberal glycaemic control in these patients.

AIM

The aim is to describe self-reported blood glucose management in patients with T2DM by intensivists working in Australian and New Zealand ICUs and to establish whether equipoise exists for a trial of liberal versus standard glycaemic control in such patients.

METHOD

An online questionnaire of Australia and New Zealand intensivists conducted in July-September 2016.

RESULTS

Seventy-one intensivists responded. Forty-five (63%) used a basic nomogram to titrate insulin. Sixty-six (93%) reported that insulin was commenced at blood glucose concentrations >10 mmol/L and titrated to achieve a blood glucose concentration between 6.0 and 10.0 mmol/L. A majority of respondents (75%) indicated that there was insufficient evidence to define optimal blood glucose targets in patients with T2DM, and 59 (83%) were prepared to enrol such patients in a clinical trial to evaluate a more liberal approach.

CONCLUSION

A majority of respondents were uncertain about the optimal blood glucose target range for patients with T2DM and would enrol such patients in a comparative trial of conventional versus liberal blood glucose control.

The impact of an education program and written guideline on adherence to low tidal volume ventilation

BACKGROUND

Low tidal volume ventilation reduces mortality in patients with acute lung injury (ALI) and may reduce the risk of ALI in ventilated patients. A previous audit of our ventilation practices showed poor adherence to low tidal volume ventilation, and we subsequently introduced written ventilation guidelines and an education program to change practice.

OBJECTIVES

To determine if adherence to low tidal volume ventilation (defined as mandatory tidal volumes of =?6.5 mL/ kg predicted body weight [PBW]) in ventilated patients was improved with a written guideline and staff education.

DESIGN AND SETTING

Retrospective analysis of recorded mandatory ventilator settings from the clinical information system of a tertiary referral intensive care unit from 1 January 2012 to 31 December 2015, involving analysis of mandatory ventilator settings in relation to PBW to determine adherence to guidelines, and interrupted time-series analysis to assess the impact of education.

MAIN OUTCOME MEASURE

Adherence to low tidal volume ventilation.

RESULTS

The mean tidal volume for the cohort was 7.4 mL/ kg (SD, 1.3 mL/kg) PBW, and 760 patients (26.9%) received an average tidal volume during mandatory ventilation of ≤6.5 mL/kg PBW. Interrupted time-series analysis showed improved adherence after education, with an increase in adherence of 29.4% (95% CI, 19.3%-39.5%) from baseline. Multivariate logistic analysis found height, weight and staff education, but not sex, were associated with adherence to low tidal volume ventilation.

CONCLUSION

Written protocols and education can influence clinician behaviour, with substantial improvements in adherence to low tidal volume ventilation. Efforts to improve adherence through ward-based education appear warranted and necessary. Adherence was strongly associated with patient height, which suggested that adherence was partly the result of chance rather than design.

Heatwave hyponatraemia: a case series at a single Victorian tertiary centre during January 2014

Heatwaves are a major public health threat for Australians. Hyponatraemia is common, with an increased incidence previously described during heatwaves. We report a series of 10 patients admitted with moderate to profound hyponatraemia, the majority with a history of excess water consumption, during the January 2014 heatwave.

Prospective observational study of emergency airway management in the critical care environment of a tertiary hospital in Melbourne

The objective of this study is to describe the population of patients receiving emergency airway management outside operating theatres at our institution, a tertiary referral centre in Melbourne. A registry of all patients receiving emergency airway management in the emergency department, ICU and on the wards as part of Medical Emergency Response teams' care, was prospectively collected. There were 128 adults and one paediatric patient requiring emergency airway management recruited to the study. Data for analysis included patient demographics, pre-oxygenation and apnoeic oxygenation, staff, drugs, details of laryngoscopic attempts, adjuncts, airway manoeuvres, complications sustained and method of confirmation of endotracheal tube placement. Over a 12-month period, there were 139 intubations of 129 patients, requiring a total of 169 attempts. Respiratory failure was the most common indication for intubation. Intubation was successful on the first episode of laryngoscopy in 116 (83.5%) patients. Complications occurred in 48 patients. In the cohort of patients without respiratory failure, nasal cannulae apnoeic oxygenation significantly reduced the incidence of hypoxaemia (0 out of 31 [0.0%] versus 10 out of 60 [16.7%], P=0.016; absolute risk reduction 16.7%; number needed to treat: 6). Waveform capnography was used to confirm endotracheal tube placement in 133 patients and there were four episodes of oesophageal intubation, all of which were recognised immediately. In the critical care environment of our institution, emergency airway management is achieved with a first-attempt success rate that is comparable to overseas data. Nasal cannulae apnoeic oxygenation appears to significantly reduce the risk of hypoxaemia in patients without respiratory failure and the use of waveform capnography eliminates episodes of unrecognised oesophageal intubation.

Do we practise low tidal-volume ventilation in the intensive care unit? a 14-year audit

BACKGROUND

Low tidal volume ventilation (LTVV) has been shown to reduce mortality of patients with acute lung injury (ALI) but uptake by clinicians has been low. Recent studies have shown that LTVV results in survival benefit at 24 months after discharge and, importantly, benefits patients without ALI.

OBJECTIVE

To determine adherence to LTVV in patients on mechanical ventilation (MV).

DESIGN, SETTING AND PARTICIPANTS

Retrospective analysis of ventilator settings recorded within the clinical information system of a 15-bed general ICU in a tertiary referral hospital, between 1 January 2000 and 31 May 2013.

METHODS

Analysis of mandatory MV with volume or pressure control.

MAIN OUTCOME MEASURES

Adherence to LTVV (_6.5 mL/ kg predicted body weight [PBW]).

RESULTS

We studied 4923 patients with a median age of 66 years (interquartile range [IQR], 57-74 years), and a median Acute Physiology and Chronic Health Evaluation II score of 16 (IQR, 13-19). Included were 3486 men (70.8%), and 3386 (66.8%) had undergone cardiac surgery. There were 249 450 ventilator measurements, with a median per patient of 75 measurements (IQR, 17-255 measurements). The median tidal volume was 8.15 mL/kg PBW (IQR, 7.15- 9.34 mL/kg PBW) for an adherence of 13.4%. Independent factors associated with adherence were sex, high inspiratory pressures, high positive end expiratory pressure and low PaO2/FiO2 ratio.

CONCLUSION

Adherence to LTVV in a general cohort of ICU patients was low, but it was better in patients with more severe lung disease. Overestimation of PBW may have contributed to our findings. Regular auditing of LTVV adherence might be considered a clinical indicator of good MV practice.

Intensive care unit admission in patients following rapid response team activation: call factors, patient characteristics and hospital outcomes

Rapid Response Systems (RRSs) have been widely introduced throughout hospital health systems, yet there is limited research on the characteristics and outcomes of patients admitted to an intensive care unit (ICU) following RRS activation. Using database extraction, this study examined the factors associated with ICU admission and patient outcome in patients receiving RRS activation in a tertiary level hospital between 2009 and 2013. Of 3004 RRS activations, 392 resulted in ICU admissions. Call factors associated with ICU admission and increased hospital mortality included tachypnoea (P <0.001 and P <0.001, respectively), hypoxia (P <0.001 and P <0.001, respectively) and having multiple Medical Emergency Team call triggers breached simultaneously (P <0.001 and P <0.001, respectively). Patients with seizures (P <0.001) and tachycardia (P=0.004) were more likely to survive to hospital discharge. Patient factors associated with ICU admission included young age (P <0.001) and having severe liver disease (P <0.001). Factors associated with increased hospital mortality included delayed RRS activation (P <0.001), increased age (P <0.001) and comorbidities including ischaemic heart disease (P=0.006), congestive heart failure (P <0.001), chronic kidney disease (P <0.001) and severe liver disease (P <0.001). Multiple factors relating to both the nature of the RRS activation call and patient characteristics are associated with ICU admission and hospital mortality post RRS activation. This information may be useful for risk stratification of deteriorating patients and determination of appropriate escalation.

The duration of hospitalization before review by the rapid response team: A retrospective cohort study

PURPOSE

The purpose of this study is to compare cases of rapid response team (RRT) review for early deterioration (<48 hours after admission), intermediate deterioration (48 to <168 hours after admission), late deterioration (≥168 hours after admission), and cardiac arrest and to determine the association between duration of hospitalization before RRT review and mortality.

METHODS

This is a retrospective cohort study of RRT cases from a single hospital over 5 years (2009-2013) using administrative data and data for the first RRT attendance of each hospital episode.

RESULTS

Of 2843 RRT cases, 971 (34.2%) were early deterioration, 917 (32.3%) intermediate, 775 (27.3%) late, and 180 (6.3%) cardiac arrest. Compared with early deterioration patients, late deterioration patients were older (median, 71 vs 69 years; P = .005), had a higher Charlson comorbidity index (median, 2 vs 1; P < .001), more often had RRT review for respiratory distress (32.5% vs 23.5%; P < .001), more often received RRT-initiated not for resuscitation orders (8.4% vs 3.9%; P < .001), less often were discharged directly home (27.9% vs 58.4%; P < .001), and more often died in hospital (30.6% vs 12.8%; P < .001). Compared with early deterioration and adjusted for confounders, the odds ratio of death in hospital for late deterioration was 2.36 (1.81-3.08; P < .001).

CONCLUSIONS

Late deterioration is frequently encountered by the RRT and, compared with early deterioration, is associated with greater clinical complexity and a worse hospital outcome.

Medical emergency teams are associated with reduced mortality across a major metropolitan health network after two years service: a retrospective study using government administrative data

Introduction

Medical emergency teams (MET) are implemented to ensure prompt clinical review of patients with deteriorating physiology with the intention of averting further deterioration, cardiac arrest and death. We sought to determine if MET implementation has led to reductions in hospital mortality across a large metropolitan health network utilising routine administrative data submitted by hospitals to the Department of Health Victoria.

Methods

The Victorian admissions episodes data set (VAED) contains data on all individual hospital separations in the State of Victoria, Australia. After gaining institutional ethics approval, we extracted data on all acute admissions to metropolitan hospitals for which we had information on the presence and timing of a MET system. Using logistic regression we determined whether there was an effect of MET implementation on mortality controlling for age, gender, Charlson comorbidity diagnostic groupings, emergency admission, same day admission, ICU admission, mechanical ventilation, year, indigenous ethnicity, liaison nurse service and hospital designation.

Results

5911533 individual admissions and 73,599 associated deaths from July 1999 to June 2010 were included in the analysis. 52.2% were male and median age was 57(42-72 IQR). Mortality rates for MET and non-MET periods were 3.92 (3.88-3.95 95%CI) and 4.56 (4.51-4.61 95%CI) deaths per 1000 patient days with a rate ratio after adjustment for year of 0.88 (0.86-0.89 95%CI) P < 0.001. In a multivariable logistic regression, mortality was associated with a MET team being active in the hospital for more than 2 years. The odds ratio for mortality in hospitals where a MET system had been in place for greater than 4 years duration was 0.90 (0.88-0.92). Mortality during the first 2 years of a MET system being in place was not statistically different from pre-MET periods.

Conclusions

Utilising routinely collected administrative data we demonstrated that the presence of a hospital MET system for greater than 2 years was associated with an independent reduction in hospital mortality across a major metropolitan health network. Mortality benefits after the introduction of a MET system take time to become apparent.

An intensivist-led tracheostomy review team is associated with shorter decannulation time and length of stay: a prospective cohort study

INTRODUCTION

Without specific strategies to address tracheostomy care on the wards, patients discharged from the intensive care unit (ICU) with a tracheostomy may receive suboptimal care. We formed an intensivist-led multidisciplinary team to oversee ward management of such patients. To evaluate the service, we compared outcomes for the first 3 years of the service with those in the year preceding the service.

METHODS

Data were prospectively collected over the course of 3 years on ICU patients not under the care of the ear, nose, and throat unit who were discharged to the ward with a tracheostomy and compared with outcomes in the year preceding the introduction of the service. Principal outcomes were decannulation time, length of stay after ICU discharge, and stay of less than 43 days (upper trim point for the disease-related group [DRG] for tracheostomy). Analysis included trend by year and multivariable analysis using a Cox proportional hazards model. P values of less than 0.05 were assumed to indicate statistical significance. As this was a quality assurance project, ethics approval was not required.

RESULTS

Two hundred eighty patients were discharged with a tracheostomy over the course of a 4-year period: 41 in 2003, 60 in 2004, 95 in 2005, and 84 in 2006. Mean age was 61.8 (13.1) years, 176 (62.9%) were male, and mean APACHE (Acute Physiology and Chronic Health Evaluation) II score was 20.4 (6.4). Length of stay after ICU decreased over time (30 [13 to 52] versus 19 [10 to 34] days; P < 0.05 for trend), and a higher proportion of decannulated patients were discharged under the upper DRG trim point of 43 days (48% versus 66%; P < 0.05). Time to decannulation after ICU discharge decreased (14 [7 to 31] versus 7 [3 to 17] days; P < 0.01 for trend). Multivariate analysis showed that the hazard for decannulation increased by 24% (3% to 49%) per year.

CONCLUSION

An intensivist-led tracheostomy team is associated with shorter decannulation time and length of stay which may result in financial savings for institutions.

Predicted body weight during mechanical ventilation: using arm demispan to aid clinical assessment

INTRODUCTION

Recent research suggests an association between the development of acute lung injury (ALI) and mechanical ventilation with tidal volumes > 6mL per kg of predicted body weight (BW). Specific subgroups (women and obese patients) may be at risk of unintentional delivery of excessive tidal volumes. We conducted a prospective audit of delivered tidal volumes (mL/kg) calculated using recorded BW and compared these to volumes calculated using predicted BW.

PARTICIPANTS AND SETTING

Patients requiring controlled mechanical ventilation admitted to a mixed intensive care unit in October 2006 were eligible. Exclusion criteria were ALI on admission or no recorded BW (defined as a weight measured by scales or a dietitian-estimated weight) for the current admission.

METHODS

Arm demispan was used to calculate height, and predicted BW was derived using ARDSNet formulas. Hourly Day 1 tidal volumes were downloaded from the medical record, and the mean for each patient was calculated. Volumes (mL/kg) were calculated using predicted and recorded BW. Data are presented as mean (SD) or median (interquartile range) depending on normality. The Mann-Whitney rank sum test was used for comparisons.

RESULTS

34 patients were studied (20 men) with a mean age of 60.6 (SD, 13.3) years and mean APACHE II score of 19.5 (SD, 6.1). Predicted BW was lower than recorded BW (69.0 [61.0-74.8] v 75 [65-85] kg; P < 0.05). Median tidal volumes (mL) were higher for men than women (552 [530- 586] v 474 [424-500] ; P < 0.01). Tidal volumes expressed as mL/kg were higher when calculated from predicted BW than from recorded BW (7.8 [7.3-8.3] v 7.2 [6.3-7.9]; P<0.05). Volumes calculated using predicted BW were higher among women than men (8.2 [7.8-8.7] v 7.5 [6.8-8]mL/kg; P < 0.05). The difference in volume between the sexes using recorded weight was not significant (7.5 [6.6-8.6] v 6.9 [6.2-7.8]mL/kg; P=0.42).

CONCLUSION

Predicted BW was significantly less than recorded BW. Consequently, larger tidal volumes were delivered on a mL/kg basis when calculated using predicted BW than recorded BW. This was particularly so for women, who received higher volumes than men when using predicted BW. Calculating predicted BW using demispan as a surrogate marker of height is a cheap, easy and noninvasive tool for clinical assessment; its use in the ICU may result in the delivery of more appropriate tidal volumes.

Mechanisms by which systemic salbutamol increases ventilation

BACKGROUND AND OBJECTIVE

Salbutamol (SAL) has systemic effects that may adversely influence ventilation in asthmatic patients. The authors sought to determine the magnitude of this effect and mechanisms by which i.v. SAL affects ventilation.

METHODS

A prospective study of nine healthy subjects (eight men, one woman; age 23 +/- 1.4 years (SD)) was undertaken. Each subject received i.v. SAL at 5, 10 and 20 microg/min each for 30 min at each dose and was observed for 1 h post infusion. Minute ventilation ((VE)), oxygen consumption (VO(2)), CO(2) production (VCO(2)), occlusion pressure (P(0.1)), heart rate, blood pressure, respiratory rate, glucose, arterial blood gases, lactate and potassium (K(+)) were recorded at baseline and at 30-min intervals. The effect of 100% oxygen on (VE) and P(0.1) during SAL infusion at 20 microg/min was observed. Results are expressed as mean +/- SEM.

RESULTS

V(E) was significantly increased at 20 microg/min SAL (37.8 +/- 12.1%, P = 0.01), as were VO(2) (22.5 +/- 5.1%, P < 0.01) and VCO(2) (40.9 +/- 10.6%, P < 0.01). Ventilation was in excess of metabolic needs as demonstrated by a rise in the respiratory exchange ratio (0.87 +/- 0.03 to 0.99 +/- 0.04, P < 0.05). Serum lactate rose by 124 +/- 30.4% from baseline to 20 microg/min (1.1 +/- 0.1 to 2.3 +/- 0.25 mmol/L, P < 0.01) and base excess decreased (0.89 +/- 0.56 to vs. -1.75 +/- 0.52 mmol/L, P < 0.01) consistent with a lactic acidosis contributing to the excess ventilation. There was no significant differences in (VE) or P(0.1) with F(I)O(2) = 1.0, suggesting peripheral chemoreceptor stimulation was not responsible for the rise in (VE). At 20 microg/min SAL, K(+) fell significantly from baseline (3.8 +/- 0.06 to 2.8 +/- 0.09 mmol/L, P < 0.001).

CONCLUSION

Systemic SAL imposes ventilatory demands by increasing metabolic rate and serum lactate. This may adversely affect patients with severe asthma with limited ventilatory reserve.

After-hours discharges from intensive care are associated with increased mortality

OBJECTIVE

To investigate the change in pattern of discharge of patients from an intensive care unit (ICU) to hospital wards and to determine the impact of discharge time on subsequent hospital mortality.

DESIGN AND PARTICIPANTS

A retrospective cohort study of 10 903 patients discharged alive from a single ICU between 1 January 1992 and 31 December 2002.

MAIN OUTCOME MEASURE

In-hospital mortality.

RESULTS

Of the 10 903 patients discharged alive from the ICU, 486 (4.5%) died in hospital wards. When discharge times were categorised according to nursing shift (morning, 07:00-14:59; afternoon, 15:00-21:59; and night, 22:00-06:59), patients were more likely to be discharged on an afternoon shift (odds ratio, 3.63; 95% CI, 3.05-4.30) or night shift (4.52; 95% CI, 3.15-6.64) in 2000-2002 compared with 1992-1994. In a multiple logistic model, hospital mortality after discharge from the ICU was increased by higher APACHE II score (1.14; 95% CI, 1.12-1.16); admission to ICU from the operating room (1.47; 95% CI, 1.11-1.95) and from the general ward (1.75; 95% CI, 1.37-2.23); and discharge during the afternoon (1.36; 95% CI, 1.08-1.70) and night shifts (1.63; 95% CI, 1.03-2.57).

CONCLUSION

Over an 11-year period, more patients are being discharged from the ICU in the afternoon and night suggesting increasing pressure on ICU beds. Patients discharged on these shifts have an increased risk of death.

Kinetic Isotope Effects and Stereochemical Studies on a Ribonuclease Model: Hydrolysis Reactions of Uridine 3'-Nitrophenyl Phosphate

The reactions of a ribonuclease model substrate, the compound uridine-3'-p-nitrophenyl phosphate, have been examined using heavy-atom isotope effects and stereochemical analysis. The cyclization of this compound is subject to catalysis by general base (by imidazole buffer), specific base (by carbonate buffer), and by acid. All three reactions proceed by the same mechanistic sequence, via cyclization to cUMP, which is stable under basic conditions but which is rapidly hydrolyzed to a mixture of 2'- and 3'-UMP under acid conditions. The isotope effects indicate that the specific base-catalyzed reaction exhibits an earlier transition state with respect to bond cleavage to the leaving group compared to the general base-catalyzed reaction. Stereochemical analysis indicates that both of the base-catalyzed reactions proceed with the same stereochemical outcome. It is concluded that the difference in the nucleophile in the two base-catalyzed reactions results in a difference in the transition state structure but both reactions are most likely concerted, with no phosphorane intermediate. The (15)N isotope effects were also measured for the reaction of the substrate with ribonuclease A. The results indicate that considerably less negative charge develops on the leaving group in the transition state than for the general base-catalyzed reaction in solution. Copyright 2000 Academic Press.

Isoxazolines as potent antagonists of the integrin alpha(v)beta(3)

Starting with lead compound 2, we sought to increase the selectivity for alpha(v)beta(3)-mediated cell adhesion by examining the effects of structural changes in both the guanidine mimetic and the substituent alpha to the carboxylate. To prepare some of the desired aminoimidazoles, a novel reductive amination utilizing a trityl-protected aminoimidazole was developed. It was found that guanidine mimetics with a wide range of pK(a)'s were potent antagonists of alpha(v)beta(3). In general, it appeared that an acylated 2-aminoimidazole guanidine mimetic imparted excellent selectivity for alpha(v)beta(3)-mediated adhesion versus alpha(IIb)beta(3)-mediated platelet aggregation, with selectivity of approximately 3 orders of magnitude observed for compounds 3g and 3h. It was also found in this series that the alpha-substituent was required for potent activity and that 2,6-disubstituted arylsulfonamides were optimal. In addition, the selective alpha(v)beta(3) antagonist 3h was found to be a potent inhibitor of alpha(v)beta(3)-mediated cell migration.

Rhizobial Nod factors stimulate somatic embryo development in Picea abies

 Nod factors are lipochitooligosaccharides (LCOs) secreted by rhizobia. Nod factors trigger the nodulation programme in a compatible host. A bioassay was set up to test how crude (NGR234) and purified (NodS) Nod factors influence cell division and somatic embryogenesis in a conifer, Norway spruce (Picea abies). The Nod factors promoted cell division in the absence of auxin and cytokinin. More detailed studies showed that NodS stimulates development of proembryogenic masses from small cell aggregates and further embryo development. However, stimulation was only observed in low-density cell cultures. Our data suggest that rhizobial Nod factors substitute for conditioning factors in embryogenic cultures of Norway spruce.

Orally active isoxazoline glycoprotein IIb/IIIa antagonists with extended duration of action

Modification of the alpha-carbamate substituent of isoxazoline GPIIb/IIIa (alphaIIb beta3) antagonist DMP 754 (7) led to a series of alpha-sulfonamide and alpha-sulfamide diaminopropionate isoxazolinylacetamides which were found to be potent inhibitors of in vitro platelet aggregation. Aryl- and heteroaryl-alpha-sulfonamide groups, in conjunction with (5R)-isoxazoline (2S)-diaminopropionate stereochemistry, were found to impart a pronounced duration of antiplatelet effect in dogs, potentially due to high affinity for unactivated platelets. Isoxazolylsulfonamide 34b (DMP 802), a highly selective GPIIb/IIIa antagonist, demonstrated a prolonged duration of action after iv and po dosing and high affinity for resting and activated platelets. The prolonged antiplatelet profile of DMP 802 in dogs and the high affinity of DMP 802 for human platelets may be predictive of clinical utility as a once-daily antiplatelet agent.

Isoxazoline GPIIb/IIIa antagonists bearing a phosphoramidate

Isoxazolinylacetamides bearing a phosphoramidate group alpha- to the carboxylate moiety (3) were prepared and evaluated for in vitro antiplatelet efficacy. They were found to bind GPIIb/IIIa with high affinity and were potent antagonists of ADP mediated platelet aggregation.

Dictyostelium discoideum fatty-acyl amidase II has deacylase activity on Rhizobium nodulation factors

Dictyostelium discoideum (Amoebidae) secretes cell-lysing enzymes: esterases, amidases, and glycosylases, many of which degrade soil bacteria to provide a source of nutrients. Two of these enzymes, fatty-acyl amidases FAA I and FAA II, act sequentially on the N-linked long chain acyl groups of lipid A, the lipid anchor of Gram-negative bacterial lipopolysaccharide. FAA I selectively hydrolyzes the 3-hydroxymyristoyl group N-linked to the proximal glucosamine residue of de-O-acylated lipid A. Substrate specificity for FAA II is less selective, but does require prior de-N-acylation of the proximal sugar, i.e. bis-N-acylated lipid A is not a substrate. We have synthesized a 14C-labeled substrate analog for FAA II and used this in a novel assay to monitor its purification. Inhibitory studies indicate that FAA II is not a serine protease, but may have a catalytic mechanism similar to metalloprotein de-N-acetylases such as LpxC. Interestingly, rhizobial Nod factor signal oligosaccharides that induce root nodules on leguminous plants have many of the structural requirements for substrate recognition by FAA II. In vitro evidence indicates that Rhizobium fredii Nod factors are selectively de-N-acylated by purified FAA II, suggesting that the enzyme may reduce the N2-fixing efficiency of Rhizobium-legume symbioses. In contrast, N-methylated Nod factors from transgenic R. fredii carrying the rhizobial nodS gene were resistant to FAA II, suggesting a mechanism by which Nod factors may be protected from enzymatic de-N-acylation. Since FAA II and Nod factors are both secreted, and Nod factors that lack the N-acyl group are unable to induce nodules, dictyostelial FAA II may decrease the efficiency of symbiotic nitrogen fixation in the environment by reducing the available biologically active nodule inducer signal.

Discovery of an orally active series of isoxazoline glycoprotein IIb/IIIa antagonists

Using isoxazoline XR299 (1a) as a starting point for the design of highly potent, long-duration GPIIb/IIIa antagonists, the effect of placing lipophilic substituents at positions alpha and beta to the carboxylate moiety was evaluated. Of the compounds studied, it was found that the n-butyl carbamate 24u exhibited superior potency and duration of ex vivo antiplatelet effects in dogs. Replacement of the benzamidin-4-yl moiety with alternative basic groups, elimination of the isoxazoline stereocenter, and reversal of the orientation of the isoxazoline ring resulted in lowered potency and/or duration of action.

Discovery of potent isoxazoline glycoprotein IIb/IIIa receptor antagonists

Using the isoxazoline as a common structural feature, three series of glycoprotein IIb/IIIa receptor antagonists were evaluated, culminating in the discovery of XR299 (30). In an in vitro assay of platelet inhibition, XR299 had an IC50 of 0.24 microM and was a potent antiplatelet agent when dosed intravenously in a canine model. It was shown through X-ray studies of the cinchonidine salt 49 that the receptor required the 5(R)-stereochemistry for high potency. The ethyl ester prodrug of XR299, XR300 (29), was orally active in the dog.