A 44 year old man, with morbid obesity (175 cm tall and 210 kg) presents to the Emergency Department with respiratory failure. He is obtunded with an arterial blood gas (ABG) showing pH 7.25, Pa C02 82 mmHg and PaO2 53 mm Hg.
CXR reveals cardiomegaly and clear lung fields.
It is day 1. He is intubated and ventilated, and no precipitant was found for his respiratory failure. CXR reveals an obscured left hemi-diaphragm and new infiltrates behind the heart.
(b) Outline your management
Ongoing management now relies on reversal of factors resulting in initial requirement for ventilation (predominantly fatigue by exclusion), removal of factors keeping him ventilator dependent, and consideration of techniques to prevent and treat left lower lobe collapse consolidation.
Reversal of initial fatigue will occur with adequate provision of rest (including sleep, and minimization of imposed work of breathing [eg. an adequate sized ETI (probably at least 8 nun), the use of the smallest amount of work to trigger the ventilator (eg. flow triggering), and the use of adequate amounts of ventilatory support (eg. pressure support, or similar mode)]. The patient will need to be awake as much as possible during the day (using appropriate sedation regimen if necessary overnight).
Left lower lobe collapse of some form may be minimized by the use of higher levels of PEEP, appropriate posturing (mcluding semi-prone and prone). and the at least intermittent use of adequate tidal volumes (eg. sigh or IMV breath). The possibility of nosocomial pneumonia and other differential diagnoses (eg. pulmonary emboli) needs to be entertained, and excluded if appropriate.