ARDS: how are we doing?

Martin Hughes

September 2010

MAIN ARTICLEAcute respiratory distress syndrome: an audit ofincidence and outcome in Scottish intensive care

unitsM. Hughes,1 F. N. MacKirdy,2 J. Ross,2 J. Norrie3 and I. S. Grant4 on behalf of the

Scottish Intensive Care Society1 Intensive Care Unit, Royal Infirmary, Castle St, Glasgow, UK

2 Scottish Intensive Care Society Audit Group, Anaesthetic Department, Victoria Infirmary, Langside Avenue, Glasgow,UK

3 Robertson Centre For Biostatistics, University of Glasgow, University Avenue, Glasgow, UK

4 Consultant, Intensive Care Unit, Western General Hospital, Crewe Road South, Edinburgh, UK

Methods

• Ward Watcher computer in each of 23 ICUs

• Midnight entry of PaO2/FiO2 (nursing staff)

• Additional data• Chest x-ray enquiry• Alternative diagnoses excluded• Diagnosis based on American European

consensus• Underlying diagnosis

Methods 2

• Daily data collection

• PaO2/FiO2

• Indices of organ dysfunction

• Ventilation modes and parameters

• Infection and antibiotics

• Specific therapies e.g. NO, prone position, steroids

• Feeding, fluid use and fluid balance

Incidence

• 8.1% of ICU admissions

• 26.1% of occupied bed days

• 16.5/100,000/year

Results

• ICU mortality• SMR• (Hospital mortality• APACHE II• Mean age• LOS mean • LOS median

19.3% 53.1% (43% - 58.2%)

0.99 1.34

28.5% 60.9%)

18.3 22.3 (21.5 - 23.7)

58.2 56.8 (55.1 - 58.5)

4.3 14.56

1.83 11

Whole population ARDS (n=375)

Ventilatory parameters day 1

• Murray 2.41/2.56

• PaO2/FiO2 118mmHg

• Mean Peak Paw 31.0 cmH2O

• Mean PEEP 7.5 cmH2O

• Mean TV 642ml (9.2ml per kg)

Univariate analysis - ICU death

• Age: Odds Ratio (OR) 1.15 (1.08, 1.23) for each 5 year increase

• Admission source: ICU/HDU/ward doubled OR compared with theatre

• Days in hospital before ICU: OR 1.04 (1.01, 1.07) for each day

Univariate analysis - ICU death

• APACHE II: OR 1.09 (1.05, 1.12) for each 1 unit increase

• SAPS II: OR 1.06 (1.04, 1.08) for each 1 unit increase

• ICU stay strongly negatively predictive: stay < 5 days 89% mortality

Univariate analysis - ICU death: Admission variables

• SBP < 90mmHg: OR 2.53 (1.55, 4.14)

• Cardiac dysrythmia: OR 2.42 (1.20, 4.90)

• ARF: OR 3.93 (2.24, 6.91)

• Immunosuppression: OR 3.24 (1.17, 8.99)

Organ failures

• Median max 2

• Survivors median max 2 (IQR 1-3)

• Non Survivors median max 3 (IQR 2-4)

• At death: 21% 1 OF, 28% 2 OF, 29% 3 OF, 17 %4 OF, 6% 5 OF.

Multivariate analysis: significant factors

• Age: 5 years OR 1.13 (1.04, 1.23)

• SAPS II: 1 unit OR 1.05 (1.03, 1.07)

• SBP < 90: OR 2.51 (1.38, 4.54)

• Days in ICU: 1 day OR 0.95 (0.93, 0.97)

• Days in hospital before ICU: 1 day OR 1.05 (1.01, 1.08)

Significant negatives

• Direct or indirect lung injury

• GCS 3 - 5

• Very severe cardiac illness

• Severe respiratory disease

• Hepatic encephalopathy, cirrhosis

• Admission time

• HR > 150, GI bleed

Why the poor mortality?

• Other studies were series in single centres

• Note France 32% vs 60%

• Small amount of trauma

• Ventilatory or other management

• Severity of illness

What should we do?

• Repeat some of the study: prospective observational cohort study

• Mortality• Underlying diagnosis and severity• Organ dysfunction and support• Ward watcher data• Ventilatory parameters• Fluid balance

Problems

• Funding

• Additional work in each unit: ventilation, fluids, diagnosis, organ dysfunction

• Data validation

Questions

• Would it be useful?

• Is it worth the additional work?

• Is there a way to simplify it?

• Is there anything else which would improve it?