A positive response to a recruitment maneuver with PEEP titration in patients with ARDS, regardless of transient oxygen desaturation during the maneuver

Recruitment maneuvers (RMs) can expand collapsed alveoli in ventilated patients. The optimal method for delivering RMs is unknown.

PURPOSE

To evaluate the safety and the respiratory and hemodynamic effects of a staircase recruitment maneuver (SRM) with decremental positive end expiratory pressure (PEEP) titration and the consequences of desaturation during the SRM in patients with early acute lung injury (ALI).

METHODS

In total, 20 consecutive patients with early ALI were enrolled and received an SRM. Patients were given 15 ± 3 cm H(2)O pressure-controlled ventilation. Positive end expiratory pressure was increased from baseline (range 10-18) to 20, 30, and 40 cm H(2)O every 2 minutes to achieve maximum alveolar pressure of 55 ± 3 cm H(2)O, then decreased at 3-minute intervals to 25, 22.5, 20, 17.5, and 15 cm H(2)O until a decrease of 1% to 2% oxygen saturation from maximum was detected. Positive end expiratory pressure was left at the level where the fall in oxygen saturation occurred. Standard respiratory and circulatory variables, arterial and central venous gases were measured before, during, and after the SRM.

RESULTS

There were significant improvements in shunt fraction (36.3% ± 10% to 26.4% ± 14%, P < .001), oxygen saturation (93.4% ± 2% to 96.8% ± 3%, P = .007), partial pressure of oxygen, arterial (PaO(2))/fraction of inspired oxygen ([FIO(2)]; 150 ± 42 to 227 ± 100, P = .004), lung compliance (33.9 ± 9.1 to 40.1 ± 11.4 mL/cm H(2)O, P < .01), and chest x-ray (CXR) after the SRM. Briefly, 80% of the patients responded and the response was maintained at 1 hour. In total, 8 patients desaturated 6.1% ± 2.8% in SaO(2) during the SRM but 5 of those improved SaO(2) relative to baseline by the end of the SRM.

CONCLUSIONS

In all, 80% of the patients with early ALI responded to the SRM with decremental PEEP titration. Desaturation during the SRM did not indicate a failed response 1 hour later.

A pilot study evaluating multiple risk factor interventions by community pharmacists to prevent cardiovascular disease: the PAART CVD pilot project

BACKGROUND

There is insufficient evidence for the efficacy of comprehensive multiple risk factor interventions by pharmacists in the primary prevention of cardiovascular disease (CVD). Given the proven benefits of pharmacist interventions for individual risk factors, it is essential that evidence for a comprehensive approach to care be generated so that pharmacists remain key members of the health care team for individuals at risk of initial onset of CVD.

OBJECTIVE

To establish the feasibility of an intervention delivered by community pharmacists to reduce the risk of primary onset of CVD.

METHODS

A single-cohort intervention study was undertaken in 2008-2009. Twelve community pharmacists from 10 pharmacies who were trained to provide lifestyle and medicine management support to reduce CVD risk recruited 70 at-risk participants aged 50-74 years who were free from diabetes or CVD. Participants received a baseline assessment to establish CVD risk and health behaviors. An assessment report provided to patients and pharmacists was used to collaboratively establish treatment goals and, over 5 sessions, implement treatment strategies. Follow-up assessment at 6 months measured changes in baseline parameters. The primary outcome was the average change to overall 5-year risk of CVD onset.

RESULTS

Sixty-seven participants were included in the analysis. The mean participant age was 60 years and 73% were female. We observed a 25% (95% CI 17 to 33) proportional risk reduction in overall CVD risk. Significant reductions also occurred in mean blood pressure (-11/-5 mm Hg) and waist circumference (-1.3 cm), with trends toward improvement for most other observed risk factors.

CONCLUSIONS

Findings support previous evidence of positive cardiovascular health outcomes following pharmacist intervention in other patient groups; we recommend generating randomized controlled trial evidence for a primary prevention population.

Increased mortality associated with after-hours and weekend admission to the intensive care unit: a retrospective analysis

OBJECTIVE

To study variation in mortality associated with time and day of admission to the intensive care unit (ICU).

DESIGN

Retrospective cohort analysis using the Australian and New Zealand Intensive Care Society Adult Patient Database.

SETTING AND PARTICIPANTS

245,057 admissions to 41 Australian ICUs from January 2000 to December 2008.

MAIN OUTCOME MEASURES

Observed mortality and standardised mortality ratio (SMR) based on Acute Physiology and Chronic Health Evaluation III, 10th iteration (APACHE III-j) scores. Subgroup analysis was performed on the basis of elective surgical or emergency admission to ICU.

RESULTS

48% of patients were admitted after hours (18:00-05:59) and 20% of patients were admitted on weekends (Saturday and Sunday). Patients admitted after hours had a 17% hospital mortality rate compared with 14% of patients admitted in hours (P < 0.001); and SMRs of 0.92 (95% CI, 0.91-0.93) and 0.83 (95% CI, 0.83-0.84), respectively. Weekend admissions had a 20% hospital mortality rate compared with 14% on weekdays (P < 0.001), with SMRs of 0.95 (95% CI, 0.94-0.97) and 0.92 (95% CI, 0.92-0.93), respectively. Variation in outcome with time of admission to ICU was accounted for predominantly by elective surgical patients.

CONCLUSIONS

Patients admitted to ICUs in Australia after hours and on weekends have a higher observed and risk-adjusted mortality than patients admitted at other times. Further research is required to determine the causes and relationship to resource availability and staffing.

A randomised controlled trial of an open lung strategy with staircase recruitment, titrated PEEP and targeted low airway pressures in patients with acute respiratory distress syndrome

INTRODUCTION

Tidal volume and plateau pressure minimisation are the standard components of a protective lung ventilation strategy for patients with acute respiratory distress syndrome (ARDS). Open lung strategies, including higher positive end-expiratory pressure (PEEP) and recruitment manoeuvres to date have not proven efficacious. This study examines the effectiveness and safety of a novel open lung strategy, which includes permissive hypercapnia, staircase recruitment manoeuvres (SRM) and low airway pressure with PEEP titration.

METHOD

Twenty ARDS patients were randomised to treatment or ARDSnet control ventilation strategies. The treatment group received SRM with decremental PEEP titration and targeted plateau pressure < 30 cm H2O. Gas exchange and lung compliance were measured daily for 7 days and plasma cytokines in the first 24 hours and on days 1, 3, 5 and 7 (mean ± SE). Duration of ventilation, ICU stay and hospital stay (median and interquartile range) and hospital survival were determined.

RESULTS

There were significant overall differences between groups when considering plasma IL-8 and TNF-α. For plasma IL-8, the control group was 41% higher than the treatment group over the seven-day period (ratio 1.41 (1.11 to 1.79), P = 0.01), while for TNF-α the control group was 20% higher over the seven-day period (ratio 1.20 (1.01 to 1.42) P = 0.05). PaO2/FIO2 (204 ± 9 versus 165 ± 9 mmHg, P = 0.005) and static lung compliance (49.1 ± 2.9 versus 33.7 ± 2.7 mls/cm H2O, P < 0.001) were higher in the treatment group than the control group over seven days. There was no difference in duration of ventilation (180 (87 to 298) versus 341 (131 to 351) hrs, P = 0.13), duration of ICU stay (9.9 (5.6 to 14.8) versus 16.0 (8.1 to 19.3) days, P = 0.19) and duration of hospital stay (17.9 (13.7 to 34.5) versus 24.7 (20.5 to 39.8) days, P = 0.16) between the treatment and control groups.

CONCLUSIONS

This open lung strategy was associated with greater amelioration in some systemic cytokines, improved oxygenation and lung compliance over seven days. A larger trial powered to examine clinically-meaningful outcomes is warranted.

TRIAL REGISTRATION

ACTRN12607000465459.

A randomised controlled trial of an open lung strategy with staircase recruitment, titrated PEEP and targeted low airway pressures in patients with acute respiratory distress syndrome

INTRODUCTION

Tidal volume and plateau pressure minimisation are the standard components of a protective lung ventilation strategy for patients with acute respiratory distress syndrome (ARDS). Open lung strategies, including higher positive end-expiratory pressure (PEEP) and recruitment manoeuvres to date have not proven efficacious. This study examines the effectiveness and safety of a novel open lung strategy, which includes permissive hypercapnia, staircase recruitment manoeuvres (SRM) and low airway pressure with PEEP titration.

METHOD

Twenty ARDS patients were randomised to treatment or ARDSnet control ventilation strategies. The treatment group received SRM with decremental PEEP titration and targeted plateau pressure < 30 cm H2O. Gas exchange and lung compliance were measured daily for 7 days and plasma cytokines in the first 24 hours and on days 1, 3, 5 and 7 (mean ± SE). Duration of ventilation, ICU stay and hospital stay (median and interquartile range) and hospital survival were determined.

RESULTS

There were significant overall differences between groups when considering plasma IL-8 and TNF-α. For plasma IL-8, the control group was 41% higher than the treatment group over the seven-day period (ratio 1.41 (1.11 to 1.79), P = 0.01), while for TNF-α the control group was 20% higher over the seven-day period (ratio 1.20 (1.01 to 1.42) P = 0.05). PaO2/FIO2 (204 ± 9 versus 165 ± 9 mmHg, P = 0.005) and static lung compliance (49.1 ± 2.9 versus 33.7 ± 2.7 mls/cm H2O, P < 0.001) were higher in the treatment group than the control group over seven days. There was no difference in duration of ventilation (180 (87 to 298) versus 341 (131 to 351) hrs, P = 0.13), duration of ICU stay (9.9 (5.6 to 14.8) versus 16.0 (8.1 to 19.3) days, P = 0.19) and duration of hospital stay (17.9 (13.7 to 34.5) versus 24.7 (20.5 to 39.8) days, P = 0.16) between the treatment and control groups.

CONCLUSIONS

This open lung strategy was associated with greater amelioration in some systemic cytokines, improved oxygenation and lung compliance over seven days. A larger trial powered to examine clinically-meaningful outcomes is warranted.

TRIAL REGISTRATION

ACTRN12607000465459.

Age of red blood cells and mortality in the critically ill

Introduction

In critically ill patients, it is uncertain whether exposure to older red blood cells (RBCs) may contribute to mortality. We therefore aimed to evaluate the association between the age of RBCs and outcome in a large unselected cohort of critically ill patients in Australia and New Zealand. We hypothesized that exposure to even a single unit of older RBCs may be associated with an increased risk of death.

Methods

We conducted a prospective, multicenter observational study in 47 ICUs during a 5-week period between August 2008 and September 2008. We included 757 critically ill adult patients receiving at least one unit of RBCs. To test our hypothesis we compared hospital mortality according to quartiles of exposure to maximum age of RBCs without and with adjustment for possible confounding factors.

Results

Compared with other quartiles (mean maximum red cell age 22.7 days; mortality 121/568 (21.3%)), patients treated with exposure to the lowest quartile of oldest RBCs (mean maximum red cell age 7.7 days; hospital mortality 25/189 (13.2%)) had an unadjusted absolute risk reduction in hospital mortality of 8.1% (95% confidence interval = 2.2 to 14.0%). After adjustment for Acute Physiology and Chronic Health Evaluation III score, other blood component transfusions, number of RBC transfusions, pretransfusion hemoglobin concentration, and cardiac surgery, the odds ratio for hospital mortality for patients exposed to the older three quartiles compared with the lowest quartile was 2.01 (95% confidence interval = 1.07 to 3.77).

Conclusions

In critically ill patients, in Australia and New Zealand, exposure to older RBCs is independently associated with an increased risk of death.

Global daily dynamics of the pineal transcriptome

Transcriptome profiling of the pineal gland has revealed night/day differences in the expression of a major fraction of the genes active in this tissue, with two-thirds of these being nocturnal increases. A set of over 600 transcripts exhibit two-fold to >100-fold daily differences in abundance. These changes appear to be primarily attributable to adrenergic-cyclic-AMP-dependent mechanisms, which are controlled via a neural pathway that includes the suprachiasmatic nucleus, the master circadian oscillator. In addition to melatonin synthesis, night/day differences in gene expression impact genes associated with several specialized functions, including the immune/inflammation response, photo-transduction, and thyroid hormone/retinoic acid biology. The following nonspecialized cellular features are also affected: adhesion, cell cycle/cell death, cytoskeleton, DNA modification, endothelium, growth, RNA modification, small molecule biology, transcription factors, vesicle biology, signaling involving Ca(2+), cyclic nucleotides, phospholipids, mitogen-activated protein kinases, the Wnt signaling pathway, and protein phosphorylation.

Inflammation in the avian spleen: timing is everything

Background

The synchrony of an organism with both its external and internal environment is critical to well-being and survival. As a result, organisms display daily cycles of physiology and behavior termed circadian rhythms. At the cellular level, circadian rhythms originate via interlocked autoregulatory feedback loops consisting of circadian clock genes and their proteins. These regulatory loops provide the molecular framework that enables the intracellular circadian timing system necessary to generate and maintain subsequent 24 hr rhythms. In the present study we examine the daily control of circadian clock genes and regulation of the inflammatory response by the circadian clock in the spleen.

Results

Our results reveal that circadian clock genes as well as proinflammatory cytokines, including Tnfά and IL-1β, display rhythmic oscillations of mRNA abundance over a 24 hr cycle. LPS-induced systemic inflammation applied at midday vs. midnight reveals a differential response of proinflammatory cytokine induction in the spleen, suggesting a daily rhythm of inflammation. Exogenous melatonin administration at midday prior to LPS stimulation conveys pleiotropic effects, enhancing and repressing inflammatory cytokines, indicating melatonin functions as both a pro- and anti-inflammatory molecule in the spleen.

Conclusion

In summary, a daily oscillation of circadian clock genes and inflammatory cytokines as well as the ability of melatonin to function as a daily mediator of inflammation provides valuable information to aid in deciphering how the circadian timing system regulates immune function at the molecular level. However, further research is needed to clarify the precise mechanisms by which the circadian clock and melatonin have an impact upon daily immune functions in the periphery.

Engaging community pharmacists in the primary prevention of cardiovascular disease: protocol for the Pharmacist Assessment of Adherence, Risk and Treatment in Cardiovascular Disease (PAART CVD) pilot study

Background

Cardiovascular disease (CVD) is the leading cause of death globally. Community pharmacist intervention studies have demonstrated clinical effectiveness for improving several leading individual CVD risk factors. Primary prevention strategies increasingly emphasise the need for consideration of overall cardiovascular risk and concurrent management of multiple risk factors. It is therefore important to demonstrate the feasibility of multiple risk factor management by community pharmacists to ensure continued currency of their role.

Methods/Design

This study will be a longitudinal pre- and post-test pilot study with a single cohort of up to 100 patients in ten pharmacies. Patients aged 50-74 years with no history of heart disease or diabetes, and taking antihypertensive or lipid-lowering medicines, will be approached for participation. Assessment of cardiovascular risk, medicines use and health behaviours will be undertaken by a research assistant at baseline and following the intervention (6 months). Validated interview scales will be used where available. Baseline data will be used by accredited medicines management pharmacists to generate a report for the treating community pharmacist. This report will highlight individual patients' overall CVD risk and individual risk factors, as well as identifying modifiable health behaviours for risk improvement and suggesting treatment and behavioural goals. The treating community pharmacist will use this information to finalise and implement a treatment plan in conjunction with the patient and their doctor. Community pharmacists will facilitate patient improvements in lifestyle, medicines adherence, and medicines management over the course of five counselling sessions with monthly intervals. The primary outcome will be the change to average overall cardiovascular risk, assessed using the Framingham risk equation.

Discussion

This study will assess the feasibility of implementing holistic primary CVD prevention programs into community pharmacy, one of the most accessible health services in most developed countries.

Trial registration

Australia and New Zealand Clinical Trial Registry Number: ACTRN12609000677202

Mortality prediction and outcomes among burns patients from Australian and New Zealand intensive care units

BACKGROUND

Acute Physiology and Chronic Health Evaluation (APACHE) III scores have been shown to correlate with outcomes for patients with burn injuries. It is unknown whether they can be used to compare outcomes between intensive care units that admit patients with burns in Australia and New Zealand.

OBJECTIVE

To assess the APACHE III-j score as a predictor of mortality for burns patients and use it to compare riskadjusted outcomes between different ICUs.

DESIGN, SETTING AND PARTICIPANTS

Retrospective cohort study of all patients listed in the Australian and New Zealand Intensive Care Society Adult Patient Database with a diagnosis of burns between 1 January 2001 and 30 June 2008. Logistic regression analysis was used to assess the relationship between APACHE III-j score and mortality, and to derive a predicted risk of death for each patient. Standardized mortality ratios for individual ICUs were calculated and outcome variation assessed.

RESULTS

Data on 1618 patients were included in the analysis (mean age, 40.6 years; mortality, 13.2%). Increasing APACHE III-j scores were significantly associated with increasing likelihood of death (odds ratio, 1.05 [95%CI, 1.04-1.06]). The largest ICU and two small ICUs had risk-adjusted outcomes that were significantly better than the rest. Over the study period there was a decline in observed mortality accompanied by a parallel reduction in predicted risk of death.

CONCLUSION

The APACHE III-j score is a good predictor of death among burns patients admitted to ICUs in Australia and New Zealand. It can be used to compare risk-adjusted outcomes between individual ICUs and over time.

A simple tool for mortality prediction in burns patients: APACHE III score and FTSA

Prediction of outcome for patients with major thermal injury is important to inform clinical decision making, alleviate individual suffering and improve hospital resource allocation. Age and burn size are widely accepted as the two largest contributors of mortality amongst burns patients. The APACHE (Acute Physiology and Chronic Health Evaluation) III-j score, which incorporates patient age, is also useful for mortality prediction, of intensive care populations. Validation for the burns specific cohort is unclear. A retrospective cohort study was performed on patients admitted to the Intensive Care Unit (ICU) via the Victorian Adult Burns Service (VABS), to compare observed mortality with burns specific markers of illness severity and APACHE III-j score. Our primary aim was to develop a mortality prediction tool for the burns population. Between January 1, 2002 and December 31, 2008, 228 patients were admitted to the ICU at The Alfred with acute burns. The mean age was 45.6 years and 81% (n=184) were male. Patients had severe injuries: the average percent TBSA (total body surface area) was 28% (IQR 10-40) and percent FTSA (full thickness surface area) was 18% (IQR 10-25). 86% (n=197) had airway involvement. Overall mortality in the 7-year period was 12% (n=27). Non-survivors were older, had larger and deeper burns, a higher incidence of deliberate self-harm, higher APACHE III-j scores and spent less time in hospital (but similar time in ICU), compared with survivors. Independent risk factors for death were percent FTSA (OR 1.03, 95% CI 1.01-1.05, p=0.01) and APACHE III-j score (OR 1.04, 95% CI 1.02-1.07, p<0.001). Mortality prediction based on both of these variables in combination was more specific than either individual variable alone (AUROC 0.85, 95% CI 0.79-0.92). Likelihood of death for patients with severe thermal injury can be predicted with accuracy from APACHE III-j score and percent FTSA. Prospective validation of our model on different burn populations is necessary.

Venous thromboembolism prophylaxis in the critically ill: a point prevalence survey of current practice in Australian and New Zealand intensive care units

BACKGROUND

Critically ill patients are at high risk of morbidity and mortality caused by venous thromboembolism (VTE). In addition to premorbid predisposing conditions, critically ill patients may be exposed to prolonged immobility, invasive intravascular catheters and frequent operative procedures, and further may have contraindications to pharmaceutical prophylactic measures designed to attenuate VTE risk. There are limited data describing current VTE prophylaxis regimens in Australia and New Zealand.

OBJECTIVE

To document current Australian and New Zealand management of VTE prophylaxis in a large mixed cohort of critically ill patients.

DESIGN

Prospective, multicentre point prevalence survey endorsed by the Australian and New Zealand Intensive Care Society Clinical Trials Group (ANZICS CTG).

SETTING

30 public hospital ICUs in Australia and New Zealand surveyed on Wednesday 9 May 2007.

METHODS

For all patients in each ICU on the study day, demographic data, admission diagnosis and information on VTE prophylaxis were prospectively collected.

RESULTS

502 patients were included in the survey, and 431 of these (86%) received VTE prophylaxis. Of these, 64% (276/431) received pharmacological prophylaxis and 80% (345/431) received mechanical prophylaxis, with 44% (190/431) receiving both. Of those receiving pharmacological prophylaxis, unfractionated heparin was used in 74%, and enoxaparin (low molecular weight heparin) in 23%. Contraindications to pharmacological prophylaxis were reported in 122 patients. Overall, pharmacological prophylaxis was administered to 87% of potentially suitable patients.

CONCLUSIONS

We observed a high prevalence of VTE prophylaxis, with many critically ill patients receiving two or more modalities of prophylaxis. These results show that the potential risk of VTE in critically ill patients is recognised in Australia and New Zealand, and strategies to mitigate this serious complication are widely implemented.

Evaluation of a community pharmacy-based intervention for improving patient adherence to antihypertensives: a randomised controlled trial

Background

The majority of patients using antihypertensive medications fail to achieve their recommended target blood pressure. Poor daily adherence with medication regimens and a lack of persistence with medication use are two of the major reasons for failure to reach target blood pressure. There is no single intervention to improve adherence with antihypertensives that is consistently effective. Community pharmacists are in an ideal position to promote adherence to chronic medications. This study aims to test a specific intervention package that could be integrated into the community pharmacy workflow to enable pharmacists to improve patient adherence and/or persistence with antihypertensive medications - Hypertension Adherence Program in Pharmacy (HAPPY).

Methods/Design

The HAPPY trial is a multi-centre prospective randomised controlled trial. Fifty-six pharmacies have been recruited from three Australian states. To identify potential patients, a software application (MedeMine CVD) extracted data from a community pharmacy dispensing software system (FRED Dispense^®). The pharmacies have been randomised to either 'Pharmacist Care Group' (PCG) or 'Usual Care Group' (UCG). To check for 'Hawthorne effect' in the UCG, a third group of patients 'Hidden Control Group' (HCG) will be identified in the UCG pharmacies, which will be made known to the pharmacists at the end of six months. Each study group requires 182 patients. Data will be collected at baseline, three and six months in the PCG and at baseline and six months in the UCG. Changes in patient adherence and persistence at the end of six months will be measured using the self-reported Morisky score, the Tool for Adherence Behaviour Screening and medication refill data.

Discussion

To our knowledge, this is the first research testing a comprehensive package of evidence-based interventions that could be integrated into the community pharmacy workflow to enable pharmacists to improve patient adherence and/or persistence with antihypertensive medications. The unique features of the HAPPY trial include the use of MedeMine CVD to identify patients who could potentially benefit from the service, control for the 'Hawthorne effect' in the UCG and the offer of the intervention package at the end of six months to patients in the UCG, a strategy that is expected to improve retention.

Trial Registration

Australian New Zealand Clinical Trial Registry ACTRN12609000705280

Pineal function: impact of microarray analysis

Microarray analysis has provided a new understanding of pineal function by identifying genes that are highly expressed in this tissue relative to other tissues and also by identifying over 600 genes that are expressed on a 24-h schedule. This effort has highlighted surprising similarity to the retina and has provided reason to explore new avenues of study including intracellular signaling, signal transduction, transcriptional cascades, thyroid/retinoic acid hormone signaling, metal biology, RNA splicing, and the role the pineal gland plays in the immune/inflammation response. The new foundation that microarray analysis has provided will broadly support future research on pineal function.

Thyroid hormone and adrenergic signaling interact to control pineal expression of the dopamine receptor D4 gene (Drd4)

Dopamine plays diverse and important roles in vertebrate biology, impacting behavior and physiology through actions mediated by specific G-protein-coupled receptors, one of which is the dopamine receptor D4 (Drd4). Here we present studies on the >100-fold daily rhythm in rat pineal Drd4 expression. Our studies indicate that Drd4 is the dominant dopamine receptor gene expressed in the pineal gland. The gene is expressed in pinealocytes at levels which are approximately 100-fold greater than in other tissues, except the retina, in which transcript levels are similar. Pineal Drd4 expression is circadian in nature and under photoneural control. Whereas most rhythmically expressed genes in the pineal are controlled by adrenergic/cAMP signaling, Drd4 expression also requires thyroid hormone. This advance raises the questions of whether Drd4 expression is regulated by this mechanism in other systems and whether thyroid hormone controls expression of other genes in the pineal gland.

Effect of pump prime on acidosis, strong-ion-difference and unmeasured ions during cardiopulmonary bypass

We tested the hypothesis that a cardiopulmonary bypass prime with lactate would be associated with less acidosis than a prime with only chloride anions because of differences in the measured strong-ion-difference. We randomised 20 patients to a 1500 ml bypass prime with either a chloride-only solution (Ringer's Injection; anions: chloride 152 mmol/l) or a lactated solution (Hartmann's solution; anions: chloride 109 mmol/l, lactate 29 mmol/l). Arterial blood was sampled before bypass and then two, five, 15 and 30 minutes after initiating bypass. We used repeated measures analysis of variance to compare groups. In both groups, the base-excess and measured strong-ion-difference decreased markedly from baseline after two minutes of bypass. The chloride-only group had greater acidosis with lower base-excess and pH (P < 0.05), greatest after five minutes of bypass (C5). Contrary to our hypothesis, however, the difference between the groups was not due to a difference in the measured strong-ion-difference, P = 0.88. At C5 when the difference in standard base-excess between the groups was greatest, 1.9 mmol/l (95% confidence interval: 0.1 to 3.6 mmol/l, P < 0.05), the difference in the measured strong-ion-difference was only 0.2 mmol/l (95% confidence interval: -2.4 to 2.7 mmol/l, P > 0.05). There was, however a difference in the net-unmeasured-ions (strong-ion-gap). We conclude that acid-base changes with cardiopulmonary bypass may differ with the prime but that the early differences between chloride-only and lactated primes appear not to be due to differences in the measured strong-ion-difference. We suggest future studies examine other possible mechanisms including unmeasured ions.

Prospective observational study of postoperative complications after percutaneous dilatational or surgical tracheostomy in critically ill patients

OBJECTIVE

To assess and describe postoperative complications of single dilator percutaneous dilatational tracheostomy (PDT) and surgical tracheostomy (ST) in a large series of critically ill patients.

METHODS

A prospective observational study was conducted in 1163 critically ill patients in a university affiliated tertiary referral hospital between 2002 and 2007. PDT was the procedure of choice for all critically ill patients requiring tracheostomy except for those with an anatomic abnormality or refractory coagulopathy, who underwent ST. Demographic and postoperative complication data were collected in a web-based database.

RESULTS

913 patients (79%) underwent PDT at the bedside in the ICU, and 250 (21%) underwent ST in the operating theatre. The tracheostomy tube was larger, and the duration of tracheostomy cannulation was shorter after PDT than after ST. The postoperative complication rate for PDT was 9.6% compared with 19.6% for ST (P<0.001). Tracheal tube obstruction and displacement were significantly less frequent after PDT (obstruction 1.0% for PDT v 3.6% for ST, P = 0.007; displacement, 1.3% for PDT v 4.8% for ST, P = 0.002).

CONCLUSIONS

In a large heterogeneous group of critically ill patients, single dilator PDT was safe and had few postoperative complications. Although ST was used in higher-risk patients, those who underwent PDT were more likely to receive a larger-sized tracheostomy tube; they were also less likely to experience obstruction or displacement of the postoperative tracheostomy tube. These differences are probably related to a combination of patient selection, smaller, shorter tracheostomy tubes, and larger tissue incision size with ST.

Prospective meta-analysis using individual patient data in intensive care medicine

Meta-analysis is a technique for combining evidence from multiple trials. However, meta-analyses of studies with substantial heterogeneity among patients within trials-common in intensive care-can lead to incorrect conclusions if performed using aggregate data. Use of individual patient data (IPD) can avoid this concern, increase the power of a meta-analysis, and is useful for exploring subgroup effects. Barriers exist to IPD meta-analysis, most of which are overcome if clinical trials are designed to prospectively facilitate the incorporation of their results with other trials. We review the features of prospective IPD meta-analysis and identify those of relevance to intensive care research. We identify three clinical questions, which are the subject of recent or planned randomised controlled trials where IPD MA offers advantages over approaches using aggregate data.

Landmark survival as an end-point for trials in critically ill patients--comparison of alternative durations of follow-up: an exploratory analysis

Introduction

Interventional ICU trials have followed up patients for variable duration. However, the optimal duration of follow-up for the determination of mortality endpoint in such trials is uncertain. We aimed to determine the most logical and practical mortality end-point in clinical trials of critically ill patients.

Methods

We performed a retrospective analysis of prospectively collected data involving 369 patients with one of the three specific diagnoses (i) Sepsis (ii) Community acquired pneumonia (iii) Non operative trauma admitted to the Royal Perth Hospital ICU, a large teaching hospital in Western Australia (WA cohort). Their in-hospital and post discharge survival outcome was assessed by linkage to the WA Death Registry. A validation cohort involving 4609 patients admitted during same time period with identical diagnoses from 55 ICUs across Australia (CORE cohort) was used to compare the patient characteristics and in-hospital survival to look at the Australia-wide applicability of the long term survival data from the WA cohort.

Results

The long term outcome data of the WA cohort indicate that mortality reached a plateau at 90 days after ICU admission particularly for sepsis and pneumonia. Mortality after hospital discharge before 90 days was not uncommon in these two groups. Severity of acute illness as measured by the total number of organ failures or acute physiology score was the main predictor of 90-day mortality. The adjusted in-hospital survival for the WA cohort was not significantly different from that of the CORE cohort in all three diagnostic groups; sepsis (P = 0.19), community acquired pneumonia (P = 0.86), non-operative trauma (P = 0.47).

Conclusions

A minimum of 90 days follow-up is necessary to fully capture the mortality effect of sepsis and community acquired pneumonia. A shorter period of follow-up time may be sufficient for non-operative trauma.

Night/day changes in pineal expression of >600 genes: central role of adrenergic/cAMP signaling

The pineal gland plays an essential role in vertebrate chronobiology by converting time into a hormonal signal, melatonin, which is always elevated at night. Here we have analyzed the rodent pineal transcriptome using Affymetrix GeneChip(R) technology to obtain a more complete description of pineal cell biology. The effort revealed that 604 genes (1,268 probe sets) with Entrez Gene identifiers are differentially expressed greater than 2-fold between midnight and mid-day (false discovery rate <0.20). Expression is greater at night in approximately 70%. These findings were supported by the results of radiochemical in situ hybridization histology and quantitative real time-PCR studies. We also found that the regulatory mechanism controlling the night/day changes in the expression of most genes involves norepinephrine-cyclic AMP signaling. Comparison of the pineal gene expression profile with that in other tissues identified 334 genes (496 probe sets) that are expressed greater than 8-fold higher in the pineal gland relative to other tissues. Of these genes, 17% are expressed at similar levels in the retina, consistent with a common evolutionary origin of these tissues. Functional categorization of the highly expressed and/or night/day differentially expressed genes identified clusters that are markers of specialized functions, including the immune/inflammation response, melatonin synthesis, photodetection, thyroid hormone signaling, and diverse aspects of cellular signaling and cell biology. These studies produce a paradigm shift in our understanding of the 24-h dynamics of the pineal gland from one focused on melatonin synthesis to one including many cellular processes.

Developmental and diurnal dynamics of Pax4 expression in the mammalian pineal gland: nocturnal down-regulation is mediated by adrenergic-cyclic adenosine 3',5'-monophosphate signaling

Pax4 is a homeobox gene that is known to be involved in embryonic development of the endocrine pancreas. In this tissue, Pax4 counters the effects of the related protein, Pax6. Pax6 is essential for development of the pineal gland. In this study we report that Pax4 is strongly expressed in the pineal gland and retina of the rat. Pineal Pax4 transcripts are low in the fetus and increase postnatally; Pax6 exhibits an inverse pattern of expression, being more strongly expressed in the fetus. In the adult the abundance of Pax4 mRNA exhibits a diurnal rhythm in the pineal gland with maximal levels occurring late during the light period. Sympathetic denervation of the pineal gland by superior cervical ganglionectomy prevents the nocturnal decrease in pineal Pax4 mRNA. At night the pineal gland is adrenergically stimulated by release of norepinephrine from the sympathetic innervation; here, we found that treatment with adrenergic agonists suppresses pineal Pax4 expression in vivo and in vitro. This suppression appears to be mediated by cAMP, a second messenger of norepinephrine in the pineal gland, based on the observation that treatment with a cAMP mimic reduces pineal Pax4 mRNA levels. These findings suggest that the nocturnal decrease in pineal Pax4 mRNA is controlled by the sympathetic neural pathway that controls pineal function acting via an adrenergic-cAMP mechanism. The daily changes in Pax4 expression may influence gene expression in the pineal gland.

Developmental and daily expression of the Pax4 and Pax6 homeobox genes in the rat retina: localization of Pax4 in photoreceptor cells

Pax4 is a homeobox gene encoding Pax4, a transcription factor that is essential for embryonic development of the endocrine pancreas. In the pancreas, Pax4 counters the effects of the related transcription factor, Pax6, which is known to be essential for eye morphogenesis. In this study, we have discovered that Pax4 is strongly expressed in retinal photoreceptors of the rat. Pax4 expression is not detectable in the foetal eye; however, postnatal Pax4 transcript levels rapidly increase. In contrast, Pax6 exhibits an inverse developmental pattern of expression being more strongly expressed in the foetal eye. Histological analysis revealed that Pax4 mRNA is exclusively expressed in the retinal photoreceptors, whereas Pax6 mRNA and protein are present in the inner nuclear layer and in the ganglion cell layer of the mature retina. In the adult retina, Pax4 transcripts exhibit a diurnal rhythm with maximal levels occurring during the light period, whereas retinal Pax6 transcript levels do not change throughout the day. The daily changes in Pax4 expression may contribute to daily changes in function in the differentiated retinal photoreceptor.