Measuring the Benefits of ALS in Prehospital Respiratory Care

Review of: Stiell IG, Spaite DW, Field B, et al: Advanced life support for out-of-hospital respiratory distress. New England Journal of Medicine. 356(21):2156 64, 2007.

The Science

This study from Canada was extracted from data collected during the Ontario Prehospital Advanced Life Support (OPALS) study. The researchers compared mortality of patients with respiratory distress in the BLS phase to that in the ALS phase. The primary difference between the two phases was the introduction of endotracheal intubation, intravenous administration of furosemide and morphine, and an increased use of nebulized bronchodilators and sublingual nitroglycerin administration.

They enrolled 8,138 patients and found that the overall mortality dropped significantly from 14.3% in Phase One to 12.4% in Phase Two. Endotracheal intubation occurred in only 1.4%. Intravenous medication administration occurred in only 15.1% of patients in Phase Two, of which the vast majority was furosemide. Symptomatic relief medication administration of nebulized salbutamol and sublingual nitroglycerin rose from 15.7% in phase one to 59.4% in Phase Two.

The authors conducted a subgroup analysis and discovered that patients with a final diagnosis of congestive heart failure (CHF) benefited the most. They further found that the vast majority of their mortality reduction occurred in cities with populations of greater than 100,000.

They concluded that, “the addition of a specific regimen of out-of-hospital [ALS] interventions to an existing EMS system that provides basic life support was associated with a decrease in the rate of death of 1.9 percentage points among patients with respiratory distress.”

The Street

I must congratulate the authors on attempting to study the impact of the introduction of these procedures into their system. However, one cannot simply take the conclusion and apply it to systems in the U.S. All pre-hospital providers in Canada are paramedics with various degrees of education. Their least trained paramedic receives almost four times as many hours of education as the nationally registered EMT-Basic.

My first point of concern is that no definition is provided for respiratory distress, other than to say that it was required that the patient complain of difficulty breathing in the absence of other complaints more indicative of a particular disease condition. This could skew the data significantly as we are well aware that patients in CHF may complain of fatigue, weakness and even chest pain.

Additionally, there is no way to determine from this study which of the interventions, if any, is responsible for the increased survival rate. The mere fact that administration of furosemide and nitroglycerin increased cannot be linked to the survival increase because there is no data presented to indicate which patients actually received these medications. Approximately 25% of the patients in both groups had CHF while 19% had chronic obstructive pulmonary disease (COPD). The implications to system oversight would be enormous if it were determined that a minority of the CHF patients got furosemide while a majority got nebulized salbutamol.

Another striking feature of this study is that the data was collected from 1995 to 1998 in Phase One and 1998 to 2000 in phase two. One has to wonder if there were changes in hospital management of these patients, which could have contributed to the lower mortality rate. While we continue to obsess about mortality rates, I believe other objective and subjective measures of the efficacy of pre-hospital care exist, such as dyspnea scores, change in vital signs and, for respiratory distress, end-tidal carbon dioxide levels as well as arterial gas measurement.

While I am a strong proponent of nebulized bronchodilators and nitroglycerin for the treatment of CHF, ample evidence supports that the routine use of diuretics increases the mortality of CHF patients. You also know that I m a proponent nebulized bronchodilators and continuous positive airway pressure (CPAP) for respiratory distress at the EMT-B level due to their high safety margin and clear clinical value.

More than anything, this paper begs the question of what is BLS and what is ALS. think this boils down more to critical thinking and the ability to develop a differential diagnosis than the number and types of skills and meds you have in your toolbox.

I hope the authors will accept my criticism with the intended respect and attempt to further refine their results to provide us a clearer picture of the cause and effect they measured. If anything, it s time we gathered similar data in the U.S. based on our scope of practice to determine what makes a difference, when it makes a difference and who should perform it.

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