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Continuous subglottic drainage in ventilated cardiac surgery patients does not significantly alter the incidence of VAP, but may delay its onset.

Citation/s:
Kollef M, et al. A randomised clinical trial of continuous aspiration of subglottic secretions in cardiac surgery patients. Chest 1999; 116: 1339-1346
Lead author's name and fax: Marin H. Kollef. kollef@pulmonary.wustl.edu

Three-part Clinical Question: Does subglottic drainage of secretions prevent ventilator-associated pneumonia in ventilated patients?

Search Terms: critical care; ventilation; subglottic drainage; pneumonia; ventilator- associated pneumonia

The Study: Single-blinded randomised controlled trial with intention-to-treat.

The Study Patients: Patients >18 years old requiring ventilation in a cardiothoracic ICU after undergoing cardiac surgery. Diagnostic criteria for VAP modified from American College of Chest Physicians criteria. Did not perform bronchoscopies.

Control group (N = 183; 183 analysed): Allocated to this group if even birth year. Same type of tracheal tube as study group, but suction port not aspirated. No other details about treatment given. Followed up until weaned from ventilator, and discharged from hospital or died.

Experimental group (N = 160; 160 analysed): Allocated to this group if odd birth year. Continuous subglottic suction not exceeding 20mmHg. No other details about treatment given. Observed daily for VAP until weaned, discharged from hospital, or died.

The Evidence:

Comments:
Data not necessarily widely applicable to other critical care populations. Likely low incidence of sepsis, different pattern of bacterial colonisation, and shorter intubation times. No information about how patients treated (eg positioning, use of stress ulcer prophylaxis, etc).

EBM Questions:

1)      Do the methods allow accurate testing of the hypothesis? Yes

2)      Do the statistical tests correctly test the results to allow differentiation of statistically significant results? Yes

3)      Are conclusions valid in light of the results? Yes. There was not a statistically significant difference in the incidence of VAP between the 2 groups. However, in the 23 patients who developed VAP, there was a highly significant difference between the groups in the number of ventilator days before VAP developed. There was no overall difference between the 2 groups in duration of ventilation, length of ICU stay, length of hospital stay or hospital mortality.

4)      Did results get omitted? No

5)      Did they suggest areas of further research? Since their results were equivocal, they suggested further clinical trials “to determine the overall impact of CASS as part of a more systematic approach to the prevention of VAP”.

6)      Did they make recommendations based on the results and were they appropriate? “Individual clinicians must decide how best to use their available resources to prevent the occurrence of VAP”. This is an appropriate recommendation.

7)      Is the study relevant to my clinical practice? Not entirely, since the study patients were all in a cardiothoracic ICU following cardiac surgery.

8)      What level of evidence does this study represent? 1⁺

9)      What grade of recommendation can I make on this result alone? B

10)   What grade of recommendation can I make when this study is considered along with other available evidence? A

11)   Should I change my practice because of these results? Not because of the results of this trial, but there is a case for a change in practice after reviewing all of the available evidence.

12)   Should I audit my current practice because of these results? I might consider auditing my current rate of VAP without using CASS and then re-audit using CASS.

Appraised by: Joyce Stuart Western General Hospital Edinburgh; 13 January 2004

Email: Joyce.Stuart@luht.scot.nhs.uk

Kill or Update By: January 2009

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