Protective Manual Hyperinflation in Acute Mechanically Ventilated Trauma Patients

Comparison of Protective Manual Hyperinflation With Current Methods in Ventilated Acute Trauma Patients: a Randomized Controlled Trial

This single-blinded randomized study aims to compare two methods of manual hyperinflation (protective - moderate tidal volumes with positive end expiratory pressure) and non-protective (large tidal volume and no positive end expiratory pressure) in ventilated acute trauma patients, to investigate the effect on inflammatory markers, lung compliance, oxygenation and sputum volume.

Current evidence in mechanical ventilation supports a "protective lung strategy" that is, smaller tidal volumes and prevention of loss of positive end expiratory pressure (PEEP). There is concern that manual hyperinflation (MHI) may conflict with this strategy and cause volutrauma and atelectrauma potentially leading to biotrauma. This single-blinded randomized study aims to compare two methods of manual hyperinflation (protective - moderate tidal volumes with positive end expiratory pressure) and non-protective (large tidal volume and no positive end expiratory pressure) in ventilated acute trauma patients, to investigate the effect on inflammatory markers, lung compliance, oxygenation and sputum volume.

Manual hyperinflation for 10 minutes using a Mapleson C circuit and 100% oxygen with volume set at 8mls/kg and positive end expiratory pressure in the circuit appropriate to baseline levels

Manual hyperinflation for 10 minutes using a Mapleson C circuit and 100% oxygen with volume set at 12mls/kg and no positive end expiratory pressure in the circuit

5 mls of arterial blood will be colected in an EDTA tube, centrifuged and aliquoted within 30 minutes. It will be stored at -80 degrees C and the analysis completed in batches by enzyme linked immunosorbent assay

5 mls of arterial blood will be colected in an EDTA tube, centrifuged and aliquoted within 30 minutes. It will be stored at -80 degrees C and the analysis completed in batches by enzyme linked immunosorbent assay

5 mls of arterial blood will be colected in an EDTA tube, centrifuged and aliquoted within 30 minutes. It will be stored at -80 degrees C and the analysis completed in batches by enzyme linked immunosorbent assay

5 mls of arterial blood will be colected in an EDTA tube, centrifuged and aliquoted within 30 minutes. It will be stored at -80 degrees C and the analysis completed in batches by enzyme linked immunosorbent assay

The ratio between the partial pressure of oxygen in arterial blood and the fraction of inspired oxygen which is delivered to the patient.

Static lung compliance is the change in volume for any given applied pressure. The formula is Compliance = Change in volume/change in pleural pressure. An inspiratory hold will be dialled on the mechanical ventilator and the static lung compliance value will be recorded from the screen.

The mean blood pressure will be recorded from the arterial catheter in situ. This is displayed continuously on the Phillips Intellivue Monitor and will be recorded for the time of intervention

Sputum will be suctioned at the end of the manual hyperinflation technique by an inline suction catheter using sterile technique into a closed sample jar. This will be weighed on an Acculab Pocket Scale PP401

Inclusion Criteria: Trauma patients Day 1 of admission to intensive care Mechanically ventilated Exclusion Criteria: Pre-existing lung disease PEEP > 12.5cmH20 Nitric oxide in circuit Haemodynamically unstable Undrained pneumothorax Intracranial pressure > 25mmHg