PHARM Podcast 009 – Prehospital airway literature updates with Dr Brian Burns
Hi folks! On this podcast I interview Dr Brian Burns, Emergency Physician and Retrieval Specialist with Greater Sydney Area HEMS service, Sydney, Australia. He is the director of clinical research for his service so knows a thing or two about clinical studies!
So naturally I had to ask him to review two latest prehospital research papers that have been released. I first met Brian last year at the AirMed conference in Brighton , UK where he presented a paper on ECMO retrievals and the New South Wales experience.
The picture of Brian is from this website, https://www.adventuremedic.com.au/advisoryboard
Now here are the two papers we discuss!
Abnormal End-Tidal Carbon Dioxide Levels on Emergency Department Arrival in Adult and Pediatric Intubated Patients
Prehospital Emergency Care, April-June 2012, Vol. 16, No. 2 , Pages 210-216
Background. The utility of prehospital intubation is controversial, as uncontrolled studies in trauma patients suggest adverse outcomes with prehospital intubation, perhaps secondary to inappropriate ventilation once intubation is accomplished.
Objectives. The objectives were 1) to establish, immediately upon arrival to the emergency department (ED), the prevalence of abnormal end-tidal carbon dioxide (ETCO2) levels in patients with prehospital intubation and 2) to describe the relationship between abnormal ETCO2 levels on ED arrival and mortality.
Methods. This was a prospective, observational cohort study of patients with prehospital intubation. Patients were excluded if they underwent prehospital cardiopulmonary resuscitation (CPR). On ED arrival, the initial ETCO2 measurement from the patient’s endotracheal tube was immediately obtained prior to purposeful intervention in the patient’s ventilation by using an Oridion Surestream Sure VentLine H Set with a Welch Allyn Propaq CS monitor. For each patient, the treating physician documented the ETCO2 measurement, patient demographics, and details of the transport. The primary outcome was an abnormal ETCO2 value (<30 mmHg or >45 mmHg). The secondary outcome was mortality.
Results. One hundred eligible patients were enrolled, with a median age of 30 years (interquartile range [IQR] 15, 48 years). Esophageal intubations were identified in four cases, and those cases were excluded from further analysis. Mechanisms included trauma, 74; medical, 12; and burn, 10. The median ETCO2 value was 32 mmHg (IQR 27, 38 mmHg), range 18–80 mmHg. Forty-six of 96 (48%, 95% confidence interval [CI] 38%, 58%) patients had abnormal ETCO2 values, including 37 (39%, 95% CI 29%, 49%) with low ETCO2 levels and nine (9%, 95% CI 4%, 17%) with high ETCO2 levels. Death was higher in those trauma patients with abnormal ETCO2 levels (10/33, 30%, 95% CI 16%, 49%) than in those with normal ETCO2 levels (2/41, 5%, 95% CI 0.6%, 17%), relative risk = 6.2 (95% CI 1.5, 26.4), p = 0.004.
Conclusion. Nearly half of all patients transported by prehospital providers had abnormal ETCO2 measurements on initial ED presentation, suggesting an area for potential improvement. Trauma patients with abnormal initial ETCO2 levels were more likely to die.
The second paper we review is
Injury. 2012 Apr 6. [Epub ahead of print]
The haemodynamic response to pre-hospital RSI in injured patients.
Source Kent, Surrey and Sussex Air Ambulance Trust, Kent, UK; London Helicopter Emergency Medical Service, The Royal London Hospital, London, UK; Trauma Sciences, Barts and The London School of Medicine and Dentistry, Queen Mary University, London, UK.
BACKGROUND: Laryngoscopy and tracheal intubation provoke a marked sympathetic response, potentially harmful in patients with cerebral or cardiovascular pathology or haemorrhage. Standard pre-hospital rapid sequence induction of anaesthesia (RSI) does not incorporate agents that attenuate this response. It is not known if a clinically significant response occurs following pre-hospital RSI or what proportion of injured patients requiring the intervention are potentially at risk in this setting.
METHODS: We performed a retrospective analysis of 115 consecutive pre-hospital RSI’s performed on trauma patients in a physician-led Helicopter Emergency Medical Service. Primary outcome was the acute haemodynamic response to the procedure. A clinically significant response was defined as a greater than 20% change from baseline recordings during laryngoscopy and intubation.
RESULTS: Laryngoscopy and intubation provoked a hypertensive response in 79% of cases. Almost one-in-ten patients experienced a greater than 100% increase in mean arterial pressure (MAP) and/or systolic blood pressure (SBP). The mean (95% CI) increase in SBP was 41(31-51) mmHg and MAP was 30(23-37) mmHg. Conditions leaving the patient vulnerable to secondary injury from a hypertensive response were common.
CONCLUSIONS: Laryngoscopy and tracheal intubation, following a standard pre-hospital RSI, commonly induced a clinically significant hypertensive response in the trauma patients studied. We believe that, although this technique is effective in securing the pre-hospital trauma airway, it is poor at attenuating adverse physiological effects that may be detrimental in this patient group.
Key messages of our review of these papers
- Monitoring ventilation and ETCO2 is vital if you are going to provide prehospital intubation, especially in head injured patients
- Oesophageal intubations in the prehospital setting will occur but failure to recognise them with gold standard monitoring such as wave form capnography is a critical patient safety indicator
- Do not forget to consider adequate analgesia in your prehospital patients and the rises in blood pressure that will occur with prehospital intubation. It is not just the hypotension that will worsen your head injured patients condition, it is the rise in intracranial pressure that may occur with the steel inotrope, your Macintosh blade!
So sit back, crack open a beer and listen to Brian and I discuss all the above. Be relaxed with Brian’s soothing Irish tones! Enjoy and stay safe out there in the prehospital world.
Now on to the Podcast
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