Evaluation of Diaphragmatic Function in Hematological Patients With Acute Hypoxemic Respiratory Failure
Conditions: Respiratory Failure, Diaphragm Injury, Ultrasound, Mechanical Ventilation Complication
Sponsor: Azienda Sanitaria-Universitaria Integrata di Udine

Study protocol 
 
Acute hypoxemic respiratory failure due to parenchymal disfunction is one of the main complications of 
immunocompromised hematological patients. In these cohort of patients mechanical ventilation is frequently 
needed  in order to restore oxygenation and normocapnia. Since every positive-pressure ventilation regimen 
may potentially determine pulmonary complications, due to alteration in pressure and volume lung 
homeostasis and diaphragm activity, also diaphragm function has to be assessed not to worsen ventilator-
induced lung injury (VILI). Main targets of VILI are pulmonary interstitium and diaphragm.   
Pulmonary interstitium is frequently involved in different mechanism of injury, that derive both from induced 
tidal volume and positive end expiratory pressure (PEEP). Indeed, large tidal volumes generated during 
assisted spontaneous breathing may configure non-protective ventilation regimens and the so called 
“pendelluft phenomenon”, that is the intrinsic flow of air within the lung from nondependent to dependent 
regions without changes in tidal volume, may affect inadequate PEEP values. 
Positive-pressure ventilation may also alter diaphragm activity. Recent data show that diaphragm disfunction, 
considered as an enhanced or reduced thickening fraction, occurs in about 65% of patients undergoing 
mechanical ventilation.  
For these reasons the evaluation of basal diaphragm activity, the choice of the device for oxygen support 
administration and the setting of ventilatory parameters become fundamental in defining hospital stay and 
outcome of patients affected by acute hypoxemic respiratory failure. 
The aim of this study is to evaluate the basal diaphragm activity of acute hypoxemic respiratory failure patients 
admitted in Intensive Care Unit (ICU) and to record diaphragm activity modifications during the ICU stay in 
relation to the optimization of medical therapy and, if necessary, according to the need of ventilatory support. 
This study intends to register also daily diaphragm thickening fraction, daily arterial blood gas analysis, failure 
frequency of non-invasive ventilation, frequency of tracheal intubation, length of mechanical ventilation, 
length of hospital stay and hospital mortality.