Specific ventilation strategies
ARDS
Defined as acute onset respiratory distress with bilateral pulmonary infiltrates on CXR with a PaO2/FiO2 <200mmHg and no evidence of left atrial hypertension.
Usually secondary to chest or systemic infection, trauma, burns.
Ventilation strategy:-
tidal volumes 5 - 7ml/kg
high PEEP (10 - 15cm)
tolerate high pCO2 provided pH >7.25
aim for sats 88 - 92%
Neuro-protective
Maintain pCO2 4.5 - 5kPa (blood gas values, not end tidal) - pCO2 major determinant of cerebral blood flow
In severe refractory intracranial hypertension maintain pCO2 4 - 4.5kPa
pCO2 < 4kPa is associated with cerebral ischaemia - it must be corrected immediately
Pulmonary hypertension
Defined as: pulmonary artery systolic pressure >60% systemic systolic pressure (by echo)
Maintain pH 7.45 - 7.5 ( may use NaHCO3 if necessary) - pH major determinant of pulmonary vascular resistance
Maintain pCO2 normal range
Keep well sedated and consider paralysing
Aim to keep systemic BP high (well filled, dopamine)
Try to keep mean airway pressures low
High FiO2 Only once these measures have failed should iNO be tried.