Association of Anaesthetists/Barema Joint Research Grants

Sheffield Teaching Hospitals NHS Foundation Trust

Title
Investigating the ability of cardiopulmonary exercise markers to predict successful extubation in intensive care (CPEXtubate)

Amount
£28,685

Scientific Abstract
Introduction: Determining whether a mechanically ventilated patient can safely tolerate extubation is an important clinical decision. The patient must have recovered sufficiently to ensure they can meet the increased metabolic demands of spontaneous ventilation. Cardiopulmonary exercise testing (CPET) equipment may be able to detect markers that indicate whether a patient is ready to cope with the physiological challenge of extubation.

Objective: This study aims to investigate whether CPET equipment can make reliable readings in mechanically ventilated patients and whether these can be interpreted to make predictions about readiness for successful extubation.

Study design: This is a prospective observational pragmatically blinded single centre study.

Study Population: Patients within a tertiary general intensive care unit being weaned and potentially considered for extubation after greater than forty-eight hours of mechanical ventilation.

Main parameters to be studied: CPET markers including RQ, RER, PETO2, PETCO2, dead space and VE/VCO2 measured before and during a spontaneous breathing trial. Important demographic and clinical data will also be collected.

Nature & extent of risks associated with participation: Considering the observational nature of the study there will be negligible risk to participating patients.

King's College London

Title
Continuous arterial oxygen monitoring to personalise ventilatory strategies

Amount
£33,412

Scientific Abstract
Mechanical ventilation has the potential to cause patient harm in both the perioperative and critical care environments. One underlying pathophysiological mechanism is cyclical atelectasis, which is currently impossible to detect at the bedside. Cyclical atelectasis is associated with intra-tidal oscillations of arterial oxygen tension (PaO2) that can be quantified with a fast-responding sensor. Measuring these respiratory PaO2 oscillations at the bedside has the potential to develop into a novel approach to diagnose cyclical atelectasis.

We propose two complementary experiments to detect PaO2 oscillations and their relationships to mechanical ventilation changes in patients with lung injury:

1) Multiple spot-ABG technique: rapid aspiration of arterial blood into 10 blood-gas syringes to demonstrate the presence of PaO2, PaCO2 and pH oscillations and determine their dominant frequency to be compared with respiratory rate.

2) External sensor experiment: slow aspiration of 10 mL of arterial blood over 50-60 seconds over a fast-acting PO2 sensor to record PaO2 oscillations. This experiment will be performed twice per patient: once at low positive end-expiratory pressure (PEEP) and high tidal volume, and once at high PEEP and low tidal volume. Primary outcomes will be detection of PaO2 oscillations and a reduction in amplitude between low and high PEEP.