Abstract
Introduction
Emergency medical services (EMS) provide prehospital care for trauma patients. Both prehospital advanced life support (ALS) and basic life support (BLS) can be performed on trauma patients in New Zealand. Multiple published systematic reviews have not found a conclusive survival benefit for trauma patients who received prehospital ALS compared to BLS, and no studies have been undertaken in New Zealand.
Aim
This thesis aimed to investigate the relationship between prehospital ALS compared to BLS and survival to hospital for major trauma patients in New Zealand.
Methods
A mixed methods approach was utilised. The quantitative phase examined routinely collected data for major trauma patients attended by a road ambulance between 1 December 2016 to 30 November 2018 in New Zealand. To estimate the odds of survival for patients who received ALS compared to BLS only, propensity scores were used to adjust for baseline differences and then incorporated in a multivariable model. The qualitative phase explored the potential implications of the quantitative results for EMS practice in New Zealand. Semi-structured interviews were undertaken with key stakeholders identified from the ambulance and trauma sector. The interview transcripts were analysed using thematic analysis.
Results
Of 1,118 attended patients that met the inclusion criteria, 59% (n=661) received ALS and 41% received BLS only (n= 457). Mortality was low with only 5% of patients (n=52) not surviving to hospital. After adjustment, the odds of survival for patients who received ALS were 1.49 times higher than patients who received BLS only (95% CI 0.66, 3.35).
Five key stakeholder organisations from the ambulance and trauma sector were identified (Hato Hone St John, Wellington Free Ambulance, Northern Rescue Helicopter Limited, National Trauma Network, and Kaunihera Manapou Paramedic Council) and a clinical leader from each organisation was interviewed. Six themes were generated from the thematic analysis: pathways and processes, the role of evidence, ambivalent thoughts on interventions, who provides care, what lies ahead, and clinical judgement. The interviewees discussed the provision of ALS in light of the quantitative results shared with them. They considered that the choice of ALS was based on the clinical judgment of ambulance officers informed by training and experience. Prehospital guidelines help reduce variation in care and in conjunction with clinical judgement, contribute to equitable outcomes. There was support for the provision of ALS for major trauma patients despite the inconclusive quantitative findings.
Conclusion
Although the adjusted odds ratio suggests that ALS provides a survival benefit for major trauma patients, the confidence interval indicates there is considerable uncertainty with the estimate. The interviewees continued to support the provision of ALS based on clinical judgement, noting that there was insufficient evidence to change current EMS practice in New Zealand. This thesis has illustrated the tension between population level data and provision of care at the individual level. Future research should examine outcomes beyond survival such as disability and quality of life.