Sun21November0437PM 12

A 27-year-old woman with adult respiratory distress syndrome (ARDS) is ventilated on intensive care.

Her inspired oxygen is 100%, positive end expiratory pressure is 15 cmH2O and peak airway pressure is 40 cmH2O.

Her arterial blood gas shows:

PaO2 6 kPa (11.3-12.6)

PaCO2 6.9 kPa (4.7-6.0)

SpO2 88% (>92%)

Which treatment is most likely to decrease mortality in this patient group?

(Please select 1 option)

Increasing tidal volume and respiratory rate on the ventilator

Prone position Incorrect answer selected

Extracorporeal membrane oxygenation (ECMO) This is the correct answer

Inhaled nitric oxide therapy

High frequency oscillatory ventilation (HFOV)

Explanation

This lady is on maximal ventilatory therapy but is still hypoxic. Her high CO2 is a reflection of permissive hypercapnia to prevent overdistension of the lungs with high tidal volumes.

Treatment of these patients used to be extremely difficult, with no significant improvement in prognosis seen will any technique. However, in 2010 the CESAR trial demonstrated a significant increase in survival without significant disability with the use of extracorporeal membrane oxygenation (ECMO).

ECMO involves connecting a patient's circulation to an external oxygenator and pump, via a catheter placed in the right side of the heart. It requires the continuous infusion of anticoagulant, and as such bleeding is the most commonly associated complication. Infection and haemolysis are also a risk. Extracorporeal membrane oxygenation (ECMO) is a treatment option considered for acute respiratory distress syndrome (ARDS) patients who are refractory to conventional treatments. However, treatment with ECMO has not shown significant reduction of mortality which may be due to inappropriate selection criteria.

A recent study1 published in the NEJM concluded that prone positioning improved outcome in severe ARDS. However, it is only one study in a controversial area. There are a number of studies, including one by the same group, which have not shown a mortality benefit (and others which show a detrimental effect on mortality). Prone positioning is therefore not yet widely accepted in clinical practice, although this may change in the future.

Reference:

Guérin C, Reignier J, Richard JC, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med. 2013;368:2159-68.

Peek GJ, et al. Randomised controlled trial and parallel economic evaluation of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR). Health Technol Assess. 2010;14:1-46.

Chest. 2017Jan; 151(1): 215-224.Treatment of ARDS With Prone Positioning

Answer Statistics

1

1%

2

86%

3

14%

4

1%

5

1%

Times answered: 370