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Hourly subglottic aspiration of secretions is consistent with a lower incidence of VAP

Citation/s:
Mahul P, et al. Prevention of nosocomial pneumonia in intubated patients: respective role of mechanical subglottic secretions drainage and stress ulcer prophylaxis. Intensive Care Medicine 1992; 18: 20-25

Lead author's name and fax: Dr Ph Mahul, Service de Reanimation, Hopital Nord, CHRU St Etienne, Av. Albert Raimond, F-42277 St Priest en Jarez, France

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 without intention-to-treat.

The Study Patients: All patients admitted to a single general ICU in a 1 year period who were expected to be intubated for more than 3 days. Randomised first to receive or not to receive subglottic secretion drainage (SSD). Then randomised to receive ulcer prophylaxis with either aluminium hydroxide or sucralfate. Therefore 4 groups analysed. VAP diagnosed if a new and persistent infiltrate appeared on the chest X-ray after 2 days or more of intubation, and an aerobic organism on BAL. "End-point day" was defined by extubation, death or diagnosis of nosocomial pneumonia.

Control group (N = 75; 75 analysed): All patients received stress ulcer prophylaxis. This was continued if enteral feeding was established. No selective decontamination of gut. On days 1, 2, 3, and then every 2nd day until "end-point day", researchers collected gastric secretions and tracheal aspirate for culture, to look for evidence of colonisation of tracheal aspirate.

Experimental group (N = 70; 70 analysed): As above, plus SSD patients all intubated with the same type of tracheal tube with an extra dorsal lumen ending just above the cuff. Intra-cuff pressure measured every 8 hours and kept up to 30mmHg. Hourly aspiration of subglottic secretions. Subglottic aspirate sent with specimens as above for culture.

The Evidence:

Comments:
No information on how patients were randomised or how they were cared for apart from that given above. Extra complexity added to a fairly small study by also comparing 2 different drugs for stress ulcer prophylaxis (which is of doubtful benefit anyway). This data was disregarded as irrelevant to the question of whether subglottic drainage affected the incidence of VAP. Did not provide data on effect of treatment group on length of ICU stay or mortality.

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

4)      Did results get omitted? Of the 158 patients originally randomised, 5 died and 8 were extubated before the end of day 3. They were not included in the subsequent data analysis.

5)      Did they suggest areas of further research? No

6)      Did they make recommendations based on the results and were they appropriate? They state that subglottic drainage of secretions halves the incidence of VAP, delays its onset and decreases the rate of colonisation of tracheal secretions, but do not make any recommendations.

7)      Is the study relevant to my clinical practice? Yes

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? Yes, if these results are considered along with the other papers.

12)   Should I audit my current practice because of these results? I should audit my current rate of VAP without using subglottic drainage and then repeat it using subglottic drainage.

Appraised by: Dr Joyce Stuart, ICU, Western General Hospital, Edinburgh EH4 2XU ; 18 November 2004

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

Kill or Update By: January 2009  

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