Web site designed and maintained by Chris Cairns  © SICS EBM Group 2004                                  

NIV reduces VAP in acute hypoxaemic respiratory failure

Citation/s:
Massimo Antonelli, Giorgio Conti et al: A comparison of noninvasive positive pressure ventilation and conventional mechanical ventilation inpatients with acute respiratory failure. NEJM 1998; 339:429-435.

Lead author's name and fax: Massimo Antonelli

Three-part Clinical Question: In intensive care patients with hypoxaemic respiratory failure, does the use of non-invasive ventilation reduce the incidence of ventilator- associated pneumonia as compared to conventional invasive ventilation?
 

Search Terms: VAP, NIV, intensive care.

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

The Study Patients: Adult patients admitted to a single ITU with acute hypoxaemic respiratory failure over the course of 1 year. Entry criteria were acute respiratory distress, deteriorating despite medical management. This was defined as a respiratory rate >35, a PaO2/FiO2 ratio of < 200mmHg while breathing oxygen from a venturi mask, using accessory muscles of respiration. Exclusion criteria included : COPD, severe haemodynamic instability, asthma, more than 2 new organ failures.

Control group (N = 32; 32 analysed): Initial mode of ventilation was assist control with TV of 10ml/kg and RR 14-18, PEEP of 5 and FiO2 0.8. PEEP was titrated upwards in increments of 2-3 cm to a maximum of 10cm to achieve FiO₂ ≤0.6. After spontaneous ventilation returned, the mode was changed to IMV with a RR of 4-7 and pressure support at 14-20 to achieve a PS TV of 8-10ml/kg, a RR of < 25 and disappearance of the use of accessory muscle activity and patient comfort. Patients were weaned using a standard protocol. No detail of sedation regimen given in the paper.

Experimental group (N = 32; 32 analysed): Full face mask ventilation was used. Pressure support was increased to achieve an expired TV of 8-10ml/kg, a RR<25, the disappearance of accessory muscle activity. PEEP was titrated upwards in increments of 2-3 cm to a maximum of 10cm to achieve FiO₂ ≤0.6.  No sedation was used. The duration of ventilation was protocolized. Criteria for intubation were failure to maintain a PaO₂> 65mmHg with FiO2 of at least 0.6, requirement for airway protection (e.g. for coma), to manage copious secretions, haemodynamic or electrocardiographic instability, or patient intolerance of the mask. NIV was discontinued when RR<30, Pa O₂>75mmHg on FiO2 0.5 with no ventilatory support.

 The Evidence:

Comments:

Do the methods allow accurate testing of the hypothesis? There is no information as to how sample size was determined. A larger study might have resulted in significant mortality data. Although the control group had a lower pH at enrollment, they were not acidaemic and this probably did not affect the result.

Do the statistical tests correctly test the results to allow differentiation of statistically significant results? Yes
Are the conclusions valid in light of the results? Yes
Did results get omitted, and why? No
Did they suggest areas of further research? No
Did they make any recommendations based on the results and are they appropriate? No
Is the study relevant to my clinical practice? Yes
What level of evidence does this study represent? Level 1⁺
What grade of recommendation can I make on this result alone? B
What grade of recommendation can I make when this study is considered along with other available evidence? N/A – single study
Should I change my practice because of these results? Yes
Should I audit my current practice because of these results? Yes – should audit the use of NIV in these patients.

Appraised by: B Miles, Stobhill Hospital, Glasgow; 20 May 2004

Email: barbara.miles.stob@northglasgow.scot.nhs.uk

Kill or Update By: 31 May 2006

Printer Friendly Version

© SICS EBM Group 2004