X3.2 Non-invasive positive pressure ventilation

Non-invasive positive pressure ventilation is effective for acute hypercapnic ventilatory failure (Ram 2004) [evidence level I]

Ventilatory support with intermittent positive pressure ven­tilation (IPPV) should be considered in patients with rising PaCO2 levels who are unable to ventilate adequately (ie, acute or acute-on-chronic respiratory acidosis) (Meyer 1994, Bott 1993, Brochard 1995, Kramer 1995, Plant 2000). This can be achieved non-invasively (by means of a face mask, NIPPV) or invasively through an endotracheal tube (Rossi 1985, Esteban 2000).

NIV is an effective and safe means of treatment of ventilatory failure. Its use allows preservation of cough, physiological air warming and humidification, and normal swallowing, feeding and speech. Early intervention with NIV is suggested when the respiratory rate is more than 30 per minute and blood pH is less than 7.35. An improvement in respiratory rate and pH usually occurs within one hour of starting NIV (Meyer 1994, Bott 1993, Brochard 1995, Kramer 1995, Plant 2000). Failure to respond or further deterio­ration would indicate a need to consider intensive care unit admission (see Box 10).

Applying non-invasive ventilation in addition to conven­tional therapy reduces mortality (Relative Risk 0.5), and the need for intubation (RR 0.4) and its potential complications. NIV results in more rapid improvements in respiratory rate, dyspnoea score and blood gas abnormalities than conventional therapy alone. Some studies have also shown an improvement in survival and a reduced length of stay in hospital (Weighted Mean Difference 3.24 days) (Ram 2004) [evidence level I].