Selected Controversies in Pre-Hospital Emergency Care

1. Selected Controversies in Pre-Hospital Emergency Care Moritz Haager PGY-2 Dr. Ian Wishart April 24, 2003

2. Objectives • Does pre-hospital intubation improve patient outcomes? • Are ALS trained crews superior to BLS only systems? • Are current fluid resuscitation protocols appropriate?

3. More is Better. Right? • Development of ALS-capable EMS systems based on assumption that earlier provision of advanced interventions will improve outcomes • “The entire basis of prehospital care is directed toward straightforward treatments that make sense based on probable cause of early death” • Hoyt. Ann Surg. 2003; 237: 161-2

4. Multicenter Canadian Study of Prehospital Trauma Care • Prospective cohort study of EMS systems in 3 major trauma centres • 9045 pts treated by BLS-EMT, PMD-ALS, or MD-ALS • 36% inc in odds of dying for MD-ALS • 21% inc in odds of dying for ALS vs BLS • Differences significant even when stratified by Injury Severity Score • Conclude that EMS-ALS crews have no benefit in trauma victims in urban centers

5. Multicenter Canadian Study of Prehospital Trauma Care • Limitations • MD’s & PMD-ALS crews saw sicker pts • Significant differences in patient population b/w cities involved • Not a randomized study

6. The Bottomline • None of the ALS interventions has been shown to be beneficial in sufficiently rigorous studies • Some (e.g. PASG, IV fluids, pediatric RSI) appear to worsen mortality • Lots of money, training, and ongoing experience required to aquire and maintain skills

7. The Bottomline • “it will be difficult for us to accept since we have so much invested in training ALS skills & because of the intuitive nature of these practices for improving outcome” • Hoyt. Ann Surg. 2003; 237: 161-2

8. AIRWAY • 1950’s – landmark studies by Elam & Safar demonstrate efficacy of rescue breathing in maintaining O2 sats @ 90%

9. Methods for Airway Control • BVM • LMA / intubating LMA • Combi-tube • ETT • Definitive, but also most complicated • Surgical airway • Where does the balance of risking aspiration vs. failed airway capture lie? Which method is most expedient?

10. Evaluating Airway Methods • Variables to consider • Time spent capturing airway • Success rate of capturing airway • Complications particular to that method • Aspiration • Failed airway • Surgical airway • Training & experience required • Practicality in anticipated environment

11. Airway Protection • Non-invasive ventilation predisposes to gastric insufflation • Increased risk of aspiration • Decreased pulmonary compliance • Risk of insufflation increases with decreasing pulmonary compliance & LES tone • Ongoing cardiac arrest + CPR • Asthma, COPD • Obesity, supine position

12. Airway Protection • 35% of arrest survivors aspirated • How does aspiration kill? • Mechanical airway obstruction • Irritant laryngo- or bronchospasm • Hemorrhagic pneumonia (~6 hrs) • ARDS • Hypoxemic respiratory failure

13. Complications of ETI • Low success rates in absence of RSI • Risk of aspiration w/ RSI • Delayed transport to hospital • Raised ICP • Unrecognized esphageal intubation • Displacement or obstruction of ETT • Pneumothorax  tension PTX

14. A Slippery Slope?

16. Should we just keep it simple?

17. BVM • “there needs to be some alternatives to BVM. Although its use has been encouraged for many years, most providers do not perform this skill well” • Wayne et al. Prehosp Emerg Care. 1999; 3: 290-6 • “In unskilled hands, maintaining a patent airway whilst at the same time attempting to ventilate the patient is not easy and is performed badly….alternative airway devices..may be better than an OPA and BVM” • Nolan. Curr Opinion Crit Care. 2001; 7:413-21

18. Tidal Volume • Balance b/w risk of gastric inflation and benefit of pulmonary ventilation • Several studies demonstrate that smaller TV’s decrease gastric distention, but may not achieve adequate P02 unless suppl O2 is used • ACLS 2000: • W/ O2 use TV 6-7 ml/kg over 2 sec • W/O O2 use TV 10 ml/kg over 2 sec

19. Pre-hospital RSI • Widespread use US; less in Canada • Locally EMS RSI introduced 2000 • Reported success rate 75-96.6% • Complication rates 5 – 13% • Cricothyrotomy rates 1.1 – 14.9% • Bulger et al. J Emerg Med 2002; 23: 181-9 • Local success rate ~84% • Calgary EMS 2-10 tubes/yr • Local cricothyrotomy rate ~3%

20. Components of EMS RSI System • NAEMSP Position Paper • Medical direction & supervison • Intensive training including OR-based experience & continuing education programs • Tools for placement confirmation & continous monitoring • Drug delivery & storage provisions • Standardized RSI protocols • Rescue methods & devices • QI / QA programs & performance reviews • Wang et al. Prehosp Emerg Care. 2001; 5: 40-8

21. Intubation Conditions • The Field • Fewest helpers & equipment • Least trained & experienced personnel • Awkward positioning & access to pt • Difficulty maintaining calm environment

22. Intubation Conditions • The ED • More help • More equipment • Better trained & more experienced personnel • Better monitoring of patient • Calmer conditions • Ability to carry out advanced interventions under sterile conditons

23. ETT Training • 20 year review of Pre-hospital ETI in Whatcom County, Washington • 1657 adults underwent RSI w/ sux • 210 (13%) aspirated (1.2% after sux) • 96.2% successfully intubated w/ sux • 3 cricothyrotomies • 6 esophageal intubations • 131 pediatric pts • 97.6% successfully intubated w/ sux • Wayne et al. Prehosp Emerg Care 1999; 13: 107-9

24. ETT Training • Pre-hospital ETI Training in Whatcom County, Washington • 2500 hrs to achieve certification • > 20 intubations in OR • > 1 ETI /month & 1/yr in OR to maintain certification in first 3 yrs • Subsequently > 1 ETI q3mo & 1 in OR • Wayne et al. Prehosp Emerg Care. 1999; 3: 290-6 • Seattle • Similar training requirements • Animal lab q2yrs for surgical airway skills • Bulger et al. J Emerg Med 2002; 23: 183-9

25. Training • “no clear consensus on the number of intubations required to train prehospital personnel adequately or on the number they need to undertake to maintain their skills. In comparison with anesthesiology trainees, all these paramedic students are undertaking far fewer intubations.” • Nolan. Curr Opinion Crit Care. 2001; 7:413-21 • Experience & success rate in anesthesia residents • >58 intubations req’d for >90% success rate • >90 intubations req’d for >95% success rate • Konrad et al. Anesth Analg. 1998; 86: 635-9

26. Success Rate • Pre-hospital intubation 75-98.4% • Paramedic students in OR setting • 94% 1st try LMA vs. 69% ETT • 10% failed ETT vs 0% LMA • Pennant & Walker. Anest Analg 1992. 74: 531-34 • Novices trained on 110 pts in OR • 94% success with LMA vs. 51% w/ ETT • Davies et al. Lancet. 1990. 336: 977

27. Failed Intubations • 56/592 (9.5%) failed PH-ETI’s • Various factors • Inadequate relaxation (no RSI) 49% • Difficult anatomy 20% • Obstruction 10% • 86% of failed pre-hospital intubations had their airway captured successfully in the ED • Predict only 3.7% of prehospital ETI would benefit from RSI drugs • Wang et al. Prehosp Emerg Care. 2001; 5: 314-141

28. How Do EP’s Compare? • NEAR (National Emergency Airway Registry) • 6294 ED intubations by EP’s • 99% success rate • Cricothyrotomy <1%

29. RSI in Seattle • Retrospective study of 2614 pts who underwent intubation • 5.4% intubation rate • 50% underwent RSI w/ Sux • 98.4% success rate • 1.1% surgical airway rate • 0.6% unabale to achieve airway – BVM • No long-term outcome, # of intubation attempts, or scene time data • Bulger et al. J Emerg Med 2002; 23: 183-9

30. Does Sux Improve Outcome? • “…whether succinylcholine-assisted ventilation makes a real difference, but not enough data are available to answer it…” • “..personal observation suggest the outcome is noticeably improved..” • “A problem with obtaining valid outcomes data is that the use of a direct control group would negate the standard of care” • Wayne et al. Prehosp Emerg Care. 1999; 3: 290-6

31. Does Sux Improve Outcome? • There really seems little doubt that use of drugs increases success rates especially in trauma pts • 4 studies totalling 2446 pts of paramedics using drugs for ETI w/ success rates of 90.5% for midaz only – 97.9% for midaz + sux • Rates for PH-ETI w/o drugs range from 49%-96% • Nolan. Curr Opinion Crit Care. 2001; 7:413-21

32. Prehospital RSI in CHI • Prospective case-control study of 209 head-injured adult trauma victims compared to 627 hand-matched controls • excluded pts intubated w/o RSI from both groups • all pts first had non-RSI attempts at ETI • paramedics had 8 hr training course in RSI • Davis et al. J Trauma. 2003; 54: 444-53

33. Inclusion Criteria • >18yo • major trauma (county protoclos) • suspected CHI • GCS 3-8 • estimated transport to ED > 10 min • unsuccessful non-RSI intubation attempt

34. Exclusion Criteria • Inabilty to capture airway (ETI or CTI) following RSI • no head injury (H + N AIS < 2) • H & N AIS defined by neck injury • failure to fulfill MTOS criteria • death in field or ED w/in 30 min of arrival • any patient intubated w/o RSI • unable to start IV or CPR before RSI

35. Outcomes • Death • “good outcome” • discharge to • home • rehabilitation (not for long term care) • psychiatry • jail • LAMA

36. Results • RSI increased successful intubations but also increased mortality (33% vs 24.2% OR 1.6 [1.2-2.2]) and decreased “good” outcomes (45.5% vs. 57.9%, OR 1.6 [1.2-2.3]) • largest difference noted for most severely injured pts • longer scene times w/ RSI • more inadvertent hyperventilation w/ RSI • inc’d mortality w/ single (37.4%) vs. multiple (26.7%) intubation attempts (no P value given)

37. Study Conclusions • Prehospital RSI causes increased mortality and morbidity • Trial suspended until cause for increased mortality can be determined

38. Criticisms • Did not compare RSI-intubated pts w/ non-RSI intubated pts • by inclusion criteria, all pts had at least 2 attempts at intubation • minimal training & experience in RSI • 67 / 209 pts ultimately had minor or no head injury • no power calculation • not randomized

39. My Conclusions • Methodologic flaws make drawing conclusions difficult • Taken together with other recent studies suggests that prehospital RSI intubation may be harmful

40. RSI • Consensus meeting failed to embrace pre-hospital RSI • Lack of evidence for its benefit • Wayne et al. Prehosp Emerg Care. 1999; 3: 290-6

41. Complications • Surgical airway • 1.1 – 14.9% • A review of failed pre-hospital airway mgmt cases demonstrated • Questionable indications for intubation • Lack of alternative rescue techniques employed prior to cricothyrotomy • Extensive complications • Mizelle et al. Prehosp Emerg Care. 2002; 6:472-75

42. Unrecognized Esophageal Intubation • PH-ETI with drugs • 0.4% rate in 2 retrospective studies • Wang et al. Prehosp Emerg Care. 2001; 5: 134-41 • Wang et al. Prehosp Emerg Care. 1999; 3: 377-78 • PH-ETI without drugs • Prospective observational study in urban EMS • 108 pts had ETT placement checked upon arrival in ED: • “Clearly misplaced” (epigastric sounds, vomitus per tube) – only in 4 / 27 pts not confirmed by direct laryngoscopy • ETCO3 for all pts • Auscaultation & direct laryngoscopy • 25% misplaced (18/27 in esophagus) • ETCO2 use in field purposely not recorded • No central direct medical oversight of EMS • Concluded rate of misplacement much higher than thought • Katz & Falk. Ann Emerg Med. 2001; 37: 62-4

43. Verifying Tube Position • ETCO2 is the recommended gold standard in all locations • Prospective study of self-inflating bulb EDD in 65 pts intubated in ED for cardiac arrest • EDD 100% (5/5) sens for esophageal placement, but 18 false +ve’s (poor spec) • ETCO2 100% sens for esophageal placement, but also no ETCO2 in 26/60 tracheal intubations • EDD & ETCO2 together only have 90.8% sensitivity for tracheal placement • Tanigawa et al. Anesthesiology. 2000; 93: 1432-6 • Other studies suggest the syringe EDD is 99% sensitive for tracheal intubation • Bozeman et al. Ann Emerg Med 1996; 27: 595-9

44. Verifying Tube Position • Other studies suggest the syringe EDD is 99% sensitive for tracheal intubation • Bozeman et al. Ann Emerg Med 1996; 27: 595-9 • Prospective randomized X-over study • 48 cardiac arrest pts intubated in ED • SIB, Syringe ETT, & ETCO2 • No sig differences b/w the 2 EDD’s • Similar sensitivity for tracheal intubation (70.8-72.9%) as previous study • 100% sens (8) for esophageal intubation • Tanigawa et al. Anesth Analg 2001; 92: 375-8 • All studies hampered by small sample size & lack of a consistent gold-standard

45. Outcome Data for ETI • “there are no well-controlled, prospective studies showing that outcome is influenced by tracheal intubation by paramedics” • Nolan. Curr Opinion Crit Care. 2001; 7:413-21

46. Outcome Data for ETI • Anti-ETI • Prospective, odd-even day randomized BVM vs. ETI analyzed as ITT analysis • 820 pts < 12 yo • 57% success rate for ETI days (174/305) • No difference in survival (OR 0.82; 95%CI 0.61-1.11) or neurological outcome (OR 0.87; 95%CI 0.62-1.22) • significantly better outcome w/ BVM in 3 subgroups • Foreign body aspiration (neuro OR 0.13; 95%CI 0.02-0.76) • Respiratory arrest b( mortalitly OR 0.27; 95%CI 0.11-0.69) • Child maltreatment (mortality OR OR 0.07; 95%CI 0.01-0.58) • no differendes in pulse oximetry • Complications: • 3 (2%) esophageal intubations • 12 (6%) unrecognized dislodgement • 33 (18%) mainstem bronchus intubation • 44 (24%) wrong tube size • 14/15 died due to esophageal intubation or dislodgement • equal rate of vomiting and aspiration in both groups • Signifantly longer scene & total transport times for ETI • Paramedics w/ adult ETI experience but only 6 hrs of classroom training in pediatric airway; no paralytics • Conclude that pre-hospital ETI does not improve outcome over BVM and should not be incorporated into EMS care • Gaushe et al. JAMA 2000; 283: 783-90

47. Outcome Data for ETI • Pro ETI • Retrospective case-control study • 1092 blunt trauma pts w/ GCS < 8 • ALS crews, no paralytics or sedation • 51.7% intubated

48. Significantly less mortality in ETI group (26%) vs non-ETI group (36%) for all comers, BUT more people able to be discharged home in non ETI group (63.1% vs. 54.8%) • odds ratio for mortality 1.6 for all pts • odds ratio for mortality 3.0 for isolated severe CHI subgroup (but no difference in morbidity) • also separately calculated Aeromedical data found sig increase in mortality for ETI pts (35%) vs non-intubated pts (21%) all comers -- attributed to sicker pts • Concluded PH-ETI saves lives • Winchell & Hoyt. Arch Surg. 1997; 132: 592-97

49. Criticisms • no comparison of intubation attempts b/w groups • no data on why the non-ETI pts were not intubated • no scene time data • not randomized or prospective • don’t comment on discrepancies, and ignore other data • no sample size estimate / power calc’n

50. My Conclusions • At best this study fails to show a difference in functional outcome • At worst it suggest that functional outcome is actually better in the non-ETI group, and that mortality is increased by ETI by aeromedical crews