Site banner

Reports of research work funded by grants prior to 2014

University of Otago Wellington

The impact of changes in mechanical ventilation and systemic perfusion on brain blood flow and oxygenation in sheep

M Berry, S Tzeng, C Marsland
Department of Paediatrics and Child Health, Department of Surgery and Anaesthesia and Department of Anaesthesia, Capital and Coast District Health Board

Phase 1 experiments have been completed in which the feasibility of conducting detailed large animal physiological studies on the Wellington Campus was established.  These experiments have been highly successful and will provide the basis for future research on this, and other critical care models.

Funding provided through the WMRF enabled purchase of a designated research portable i-stat blood gas anaylser and the probes necessary for direct arterial flow measurement.

Specific project goals were achieved as follows:

  • Development of a collaborative multidisciplinary team comprising CCDHB clinicians and University of Otago academics
  • Development of a suite of state of the art physiological data acquisition equipment for animal studies; these can be easily modified to accommodate a range of species and experimental paradigms
  • Refinement of anaesthetic protocols for sheep using inhalational or total intravenous anaesthesia
  • Development of a robust experimental model of acute airway obstruction and resuscitation techniques
  • Development of the methodology for optimal trans-tracheal catheter placement under bronchoscopic guidance
  • Development of a technique for continuous closed airway pressure monitoring
  • Successful placement of arterial and central venous vascular catheters for continuous arterial and venous pressure monitoring
  • Rapid modulation of ventilation support parameters based on feed back provided by the i-STAT blood gas unitDevelopment of the techniques needed for reliable carotid and systemic arterial flow measurements

These preliminary experiments have been highly productive and are of significant strategic importance for translational biomedical research at the University of Otago, Wellington campus.  We have successfully demonstrated how academics and clinicians can work collaboratively to produce clinically relevant, novel, high calibre physiological studies in the UOW Biomedical Research Unit.

Outputs to date:

  • Dr Colin Marsland (in collaboration with Drs Berry and Tzeng); The Ritchie Prize (a prestigious prize awarded annually and sponsored by the New Zealand Society of Anaesthetists) for studies based on the acute cardio-respiratory consequences of emergency trans-tracheal ventilation.
  • Establishment of a critical airway management course using our instrumented sheep model in conjunction with the CCDHB ‘Sim-suite’. This allows clinicians to see in real time the effects of changes in ventilation technique in an emergency airway scenario on key physiological parameters.  This gives valuable high-fidelity training on resuscitation techniques that cannot be developed in a clinical emergency, or in a ‘Sim-suite’ environment alone.  The feedback from clinicians has been superb (‘best educational course in my 38 year career’) and it has highlighted the research opportunities available to clinicians through the Biomedical Research Unit.
  • Publication: Percutaneous transtracheal ventilation in an obstructed airway model in post-apnoeic sheep. British Journal of Anaesthesia doi:10.1093/bja/aeu188. Epub ahead of print, June 30th (Manuscript attached).

The funding support of the WMRF has been integral to the success of these experiments, and as such has been acknowledged in the manuscript described above and all forums where this work has been presented.  The equipment funded is also being used to support studies looking at the detailed haemodynamic effects of cerebral ischaemia in a rat stroke model, and Phase 2 sheep and preterm lamb studies exploring in more detail the cerebral flow characteristics across a range of neurocritical care scenarios are planned.  Access to a designated research i-stat blood gas analyser has also facilitated other human research initiatives run through the Centre for Translational Physiology (for instance, in conjunction with Well Sleep, the respiratory status of subjects with obesity hyperventilation syndrome). This has added to both the safety and quality of research, and thus supported a broad range of collaborative research on the Wellington campus. 

We are extremely grateful for the support of the Wellington Medical Research Foundation and their contribution towards the work that we do.

The impact of changes in mechanical ventilation and systemic perfusion on brain blood flow and oxygenation in sheep

+ Text Size -