Table 1 Studies of advanced life support systems and interventions

In support of ALS systems

Roudsari and colleagues [14]

Multicenter, multinational, ecological study

Countries with physician-provided ALS compared with countries with paramedic-provided ALS

Lower early (24 hour) mortality with physician-provided ALS

Heterogeneity in the types of prehospital and inhospital care across countries with apparent similar prehospital models of care precludes attributing improved outcomes to physician-provided ALS alone

Physician and paramedic providers

Lower mortality to hospital discharge among those with ISS >25

Adult, major trauma

Klemen and Grmec [16]

Single-center, retrospective cohort study

ALS with ETI by physicians compared with BLS by paramedics

No difference in overall survival

Possible measurement bias in recording GCS

Urban/physician and paramedic providers

Improved early (1 hour, 24 hour) survival and functional outcomes with physician providers

Crossover between groups

Adult, moderate to severe head injury with ISS >15

Lower mortality among patients with GCS of 6 to 8 with physician providers

Messick and colleagues [13]

Multicenter, ecological study

Counties with ALS programs compared with counties with BLS programs

ALS program availability an independent predictor of lower per-capita county trauma death rates

Significant residual confounding as BLS counties were significantly more rural

Urban and rural/paramedic providers

Adult and pediatric, major trauma

Honigman and colleagues [9]

Single center, case series

ALS (ETI, intravenous, PASG)

Scene time did not adversely affect outcome

No direct comparison of BLS with ALS

Urban/paramedic providers

Scene time independent of field procedures performed and mortality

Not generalizable to greater spectrum of trauma patients

Adult, penetrating cardiac injuries

Jacobs and colleagues [10]

Single-center, prospective cohort study

ALS-trained paramedics (ETI, intravenous, PASG) compared with BLS-trained paramedics

Improvement in trauma score in prehospital setting with ALS

ALS care assignment nonrandom

Urban/paramedic providers

ALS not an independent predictor of survival

Adult and pediatric, major trauma

Aprahamian and colleagues [11]

Single center, before/after design

New ALS program (ETI, intravenous, thoracentesis, pericardiocentesis) compared with police-provided ambulance service

Lower mortality among patients with prehospital systolic blood pressure<60 mmHg

Historical controls fail to take into consideration other changes in care

Urban/paramedic providers

Adult, penetrating injuries

Fortner and colleagues [12]

Two centers, before/after design

ALS program (ETI, intravenous) compared with BLS program

Greater proportion of patients surviving to reach hospital and surviving to hospital discharge

Historical controls

Urban/paramedic providers

Specific interventions were not documented

Adult, falls from significant height

In support of ALS interventions

Bulger and colleagues [24]

Single-center, retrospective cohort study

Prehospital ETI with RSI compared with prehospital ETI without RSI

Lower mortality with prehospital RSI

Nonrandom selection

Urban/paramedic and nurse providers

Lower mortality with prehospital RSI among patients with GCS <9

Possible confounding by indication; patients not receiving RSI probably agonal

Adult, moderate to severe head injury

Improved functional outcomes with prehospital RSI among patients with GCS <9

Bushby and colleagues [15]

Single-center, retrospective, TRISS analysis

Intubation, needle chest decompression

Prehospital intubation, chest decompression associated with better than expected outcomes

Historic controls (TRISS methodology)

Urban and rural/paramedic providers

Long prehospital times among large proportion of patients limit generalizability

Adult, blunt injuries causing moderate to severe thoracic injuries

Arbabi and colleagues [17]

Two centers, retrospective cohort study

Prehospital ETI compared with emergency department ETI and nonintubated patients

Higher mortality with emergency department ETI compared with prehospital ETI

Nonrandom selection and potential for residual confounding

Urban/paramedic providers

No difference in survival with prehospital ETI compared with no intubation

Adult, major trauma

Winchell and Hoyt [18]

Multicenter, retrospective cohort study

Prehospital ETI compared with nonintubated patients

Lower mortality among intubated patients

Nonrandom selection

Urban and rural/paramedics

Lower mortality among intubated patients with severe head injuries

Residual confounding (no adjustment for age, ISS, shock)

Adult, blunt injuries, GCS <9

In support of BLS systems

Stiell and colleagues [32]

Multicenter, before/after design

New ALS program (ETI, intravenous, administration of medication) compared with BLS program

No difference in survival

Study conducted early after implementation of ALS – may not reflect mature prehospital system

Urban/paramedic providers

Higher mortality among patients with GCS <9 after implementation of ALS program

Relatively few patients received ALS interventions after implementation of ALS program

Adult, major trauma

Liberman and colleagues [31]

Multicenter, retrospective cohort study

ALS care (physician or paramedic provided) compared with BLS care (paramedic provided)

Higher mortality with onscene treatment by physicians

Nonrandom assignment of ALS care, likely confounding by indication

Urban/physician and paramedic providers

Higher mortality with prehospital ALS

Adult, major trauma

Di Bartolomeo and colleagues [29]

Multicenter, prospective cohort study

Prehospital ALS by physician (air transport) compared with BLS by paramedics (ground transport)

No difference in mortality with prehospital ALS provided by physicians

Prolonged transport times with frequent interfacility transfers limit generalizability

Urban and rural/physician and paramedic providers

Adult and pediatric, severe head injury

Eckstein and colleagues [20]

Single-center, retrospective cohort study

Prehospital ETI compared with prehospital BVM and emergency department ETI

Higher mortality with prehospital ETI

Nonrandomized with possible confounding by indication

Urban/paramedic providers

Prehospital intravenous fluids compared with no prehospital intravenous fluids

Adult and pediatric, major trauma

Cayten and colleagues [27]

Multicenter, retrospective, TRISS analysis

ALS units (ETI, intravenous fluids, PASG) compared with BLS units

Improved prehospital RTS with ALS

Biased exclusion of patients due to missing data

Urban/paramedic providers

No improvement in predicted mortality with ALS

Variable expertise among providers

Patients aged >12 years, major trauma

Higher than predicted mortality for patients with penetrating injuries receiving ALS care

Historic controls (TRISS methodology)

Sampalis and colleagues [30]

Multicenter, retrospective cohort study

ALS care (physician provided) compared with BLS care (physician or paramedic provided)

No difference in mortality

Nonrandom assignment of ALS care, likely confounding by indication

Urban/physician and paramedic providers

Adult and pediatric, major trauma

Potter and colleagues [25]

Multicenter, prospective cohort study

ALS prehospital care compared with BLS prehospital care

Lower rate of early deaths (24 hours) with prehospital ALS, yet no improvement in survival to hospital discharge

Nonrandom assignment of ALS, likely confounding by indication

Urban/paramedic providers

Ad hoc presence of physicians with BLS crew renders attribution of outcomes to ALS versus BLS crew difficult

Adult, major trauma and burns

Ivatury and colleagues [34]

Single-center, retrospective cohort study

Field stabilization (ETI, intravenous, PASG, drug administration) compared with direct transport

Lower survival among patients with field stabilization attempts

Wide range of ALS procedures, some with low success rates

Urban/paramedic providers

Confounding by indication likely

Patients with penetrating thoracic injuries, in extremis, requiring emergency department thoracotomy

In support of BLS interventions

Davis and colleagues [19]

Multicenter, retrospective cohort study

Prehospital ETI compared with emergency department ETI

Higher mortality with prehospital ETI

Nonrandomized with possible confounding by indication

Urban/paramedic providers

Higher mortality with prehospital ETI among patients with severe head injuries

Adult, moderate to severe head injury

DiRusso and colleagues [39]

Multicenter, retrospective cohort study

Prehospital ETI compared with emergency department ETI and nonintubated patients

Higher mortality with prehospital ETI

No information about provider type

Urban and rural/paramedic providers

Worse functional outcomes at discharge with prehospital ETI

Nonrandomized with possible confounding by indication

Pediatric, major trauma

Stockinger and McSwain [21]

Single-center, retrospective cohort study

Prehospital ETI compared with prehospital BVM

Higher mortality with ETI compared with BVM

Nonrandomized with possible confounding by indication

Urban/paramedic providers

Higher than predicted mortality with ETI among patients with penetrating injuries using the TRISS methodology

Adult, major trauma, receiving prehospital ETI or BVM

Mortality as predicted among patients with blunt injuries receiving ETI

Wang and colleagues [37]

Multicenter, retrospective cohort study

Prehospital ETI compared with emergency department ETI

Higher mortality with prehospital ETI

Nonrandomized with possible confounding by indication

Urban and rural/paramedic providers

Adult, moderate to severe head injury

Davis and colleagues [42]

Multicenter, retrospective matched cohort study

Prehospital ETI attempted with RSI compared with matched nonintubated historical controls

Higher mortality with prehospital RSI

Nonrandomized with possible confounding by indication

Urban/paramedic providers

Higher mortality related to hypocapnea on arrival

Adult, moderate to severe head injury

Murray and colleagues [38]

Multicenter, retrospective cohort study

Prehospital ETI compared with attempted ETI or nonintubated patients

Higher mortality with prehospital ETI compared with nonintubated patients

Nonrandomized with possible confounding by indication

Urban/paramedic providers

Higher mortality with prehospital ETI compared with attempted ETI

Adult and pediatric, severe head injury

Sloane and colleagues [36]

Single-center, retrospective cohort study

Prehospital ETI compared with emergency department ETI

No difference in mortality in subgroup analysis of patients with isolated head injuries

Small sample size with potential for type II error

Urban/aeromedical crews, physician, paramedic or nurse provider

Overall mortality effect not reported

Adult, major trauma

Bickell and colleagues [33]

Single-center, prospective, unblinded quasirandomized study (alternate-day assignment)

Prehospital fluid resuscitation compared with delayed fluid resuscitation (once hemorrhage controlled)

Lower mortality with delayed resuscitation

Not generalizable to wider spectrum of trauma patients

Urban/paramedic providers

Shorter length of stay with delayed resuscitation

Adult, penetrating torso injuries causing hypotension and operative intervention