OPALS Study; COMPRESSIONS-ONLY CPR; BYSTANDERS; HYPERVENTILATION

ALS Benefit for Respiratory Distress
     Stiell IG, Spaite DW, Field B, et al. Advanced life support for out-of-hospital respiratory distress. New England Journal of Medicine 356(21):2,156-;64, May 24, 2007.

     Abstract: Respiratory distress is a common symptom of patients transported to hospitals by emergency medical services personnel. The benefit of advanced life support for such patients has not been established. Methods-The Ontario Prehospital Advanced Life Support (OPALS) Study was a controlled clinical trial conducted in 15 cities before and after the implementation of a program to provide advanced life support for patients with out-of-hospital respiratory distress. Paramedics were trained in standard advanced life support, including endotracheal intubation and the administration of intravenous drugs. Results-The clinical characteristics of the 8,138 patients in the two phases of the study were similar. During the first phase, no patients were treated by paramedics trained in advanced life support; during the second phase, 56.6% of patients received this treatment. Endotracheal intubation was performed in 1.4% of the patients, and intravenous drugs were administered to 15.0% during the second phase. This phase of the study was also marked by a substantial increase in the use of nebulized albuterol and sublingual nitroglycerin for the relief of symptoms. The rate of death among all patients decreased significantly, from 14.3% to 12.4% (absolute difference 1.9%; 95% CI, 0.4-;3.4; p=0.01) from the basic life support phase to the advanced life support phase (adjusted odds ratio 1.3; 95% CI, 1.1-;1.5). Conclusions-The addition of a specific regimen of out-of-hospital advanced life support 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.

     Comment: This is good evidence that the prompt and correct treatment of patients with respiratory distress results in better immediate (greater prehospital improvement, lower incidence of ED intubation) and long-term (reduced mortality, better overall cerebral function) outcome. These are important results that identify a group of patients prehospital ALS treatment is likely to help.

     Perhaps even more promising is that the majority of the reduction in mortality was seen in patients with congestive heart failure (CHF). Our treatments for CHF have greatly improved since this study was concluded in 2000. With a de-emphasis or elimination of morphine and furosemide (Lasix), higher doses of nitroglycerin and the addition of CPAP (and perhaps even captopril), one would expect that outcomes today would be even better.

     As we learn more from excellent studies such as these, it helps us focus our quality improvement efforts. Previous OPALS papers have concluded that ALS care improves outcomes in patients with chest pain, but not cardiac arrest (where CPR and defibrillation are most important) or trauma. EMS systems should keep the treatment of chest pain and respiratory distress patients as high priorities in their QI systems.

CPR With Chest Compressions Only
     SOS-KANTO study group. Cardiopulmonary resuscitation by bystanders with chest compression only: An observational study. Lancet 369(9,565):920-;6, Mar 17, 2007.

     Abstract: Mouth-to-mouth ventilation is a barrier to bystanders doing cardiopulmonary resuscitation (CPR), but few clinical studies have investigated the efficacy of bystander resuscitation by chest compressions without mouth-to-mouth ventilation (cardiac-only resuscitation). This is a prospective, multicenter observational study of patients who had out-of-hospital cardiac arrest. On arrival at the scene, paramedics assessed the technique of bystander resuscitation. The primary endpoint was favorable neurological outcome 30 days after cardiac arrest. 4,068 adult patients who had out-of-hospital cardiac arrest witnessed by bystanders were included; 439 (11%) received cardiac-only resuscitation from bystanders, 712 (18%) received conventional CPR, and 2,917 (72%) received no bystander CPR. Any resuscitation attempt was associated with a higher proportion having favorable neurological outcomes than no resuscitation (5.0% vs. 2.2%, p-lt;0.0001). Cardiac-only resuscitation resulted in a higher proportion of patients with favorable neurological outcomes than conventional CPR in patients with apnea (6.2% vs. 3.1%, p=0.0195), with shockable rhythms (19.4% vs. 11.2%, p=0.041), and with resuscitation that started within four minutes of arrest (10.1% vs. 5.1%, p=0.0221). However, there was no evidence for any benefit from the addition of mouth-to-mouth ventilation in any subgroup. The adjusted odds ratio for a favorable neurological outcome after cardiac-only resuscitation was 2.2 (95% CI, 1.2-;4.2) in patients who received any resuscitation from bystanders.

     Interpretation-Cardiac-only resuscitation by bystanders is the preferable approach to resuscitation for adult patients with witnessed out-of-hospital cardiac arrest, especially those with apnea, shockable rhythms or short periods of untreated arrest.

     Comment: A number of animal studies have concluded that chest-compression-only (CCC, or continuous-chest-compression) CPR is as effective as, or more effective than, standard CPR in treating cardiac arrest, and this is strong evidence that the same is true in humans. The authors compare bystander performance of cardiac-only CPR with standard CPR in a real-world community setting. For patients with shockable rhythms (VT or VF) or who had CPR started within four minutes of collapse, the survival with CCC-CPR was double that of those who had conventional CPR. For many groups the survival was marginally increased, and for no group was the survival better with conventional CPR.

     An accompanying editorial (Ewy GA. Cardiac arrest-guideline changes urgently needed. Lancet 369:882, Mar 17, 2007) describes the many reasons for this finding. Ventilations delay the start of, and create long pauses in, chest compressions. They raise intrathoracic pressure, which squeezes blood out of the chest and further reduces brain circulation. And there is no evidence that artificial ventilations are helpful, at least for the first few minutes of a cardiac arrest, as there is a large amount of oxygen already in the blood, and early and effective chest compressions will prolong agonal gasps and continue the supply of oxygen.

     Curiously, in Dr. William B. Kouwenhoven's first published study in 1960, he described his success in using only chest compressions to resuscitate a number of patients. Soon thereafter, and perhaps unfortunately, he and Dr. Peter Safar added mouth-to-mouth ventilations to create modern CPR. It may very well be time to go back to Kouwenhoven's original method.

Bystander CPR: Who and Where?
     Vadeboncoeur T, Bobrow BJ, Clark L, et al. The Save Hearts in Arizona Registry and Education (SHARE) program: Who is performing CPR and where are they doing it? Resuscitation, Apr 28, 2007 [e-pub ahead of print].

     Abstract: Bystander CPR decreases mortality from out-of-hospital cardiac arrest significantly. Accordingly, layperson CPR is an integral component in the chain of survival for out-of-hospital cardiac arrest victims. The statewide [Arizona] incidence and location of layperson CPR is unknown. Objective-To determine true incidence and location of layperson CPR in the state of Arizona. Methods-The Save Hearts in Arizona Registry and Education (SHARE) program reviewed EMS first care reports submitted voluntarily by 30 municipal fire departments responsible for approximately 67% of Arizona's population. In addition to standard Utstein-style data, information regarding the performance of bystander CPR, the vocation and medical training of the bystander and the location of the arrest were documented. Results-The total number of out-of-hospital adult arrests of presumed cardiac etiology reported statewide was 1,097. Cardiac arrests occurred in private residences in 67% [of these cases], extended care or medical facilities in 18%, and public locations in 15%. Bystander CPR was performed in 37% of all arrests, 24% of residential arrests, 76% of extended care or medical facility arrests, and 52% of public arrests. Bystander CPR provided an odds ratio of 2.2 for survival [95% CI, 1.2-;4.1]. Excluding cardiac arrests which occurred in the presence of bystanders with formal CPR training as part of their job description, layperson CPR was performed in 218 of 857 (25%) cases. Conclusions-The near statewide incidence of layperson CPR is extremely low. This low rate of bystander CPR is likely to contribute to the low overall survival rates from cardiac arrest. Public health officials should re-evaluate current models of public education on CPR.

     Comment: This is the most recent of many studies that continue to show that bystander CPR rates are dismally low. As we learn more about the value of CPR in improving patient outcomes, this becomes an increasingly important topic. Previous studies also tell us why this is the case. One of the most important barriers is reluctance to perform mouth-to-mouth ventilation. Another, also the subject of numerous prior studies, is the method of CPR instruction. Short, individual video-based courses are equivalent or superior to conventional four-hour CPR training sessions in learning essential skills, and for many are far more desirable.

     The net result is that we rarely achieve the chain of survival, and much more commonly witness a cycle of failure. Barriers to learning and performing CPR keep more people from participating, bystanders are unwilling and/or unable to perform CPR when it is needed, and the resulting low rate of survival keeps us from realizing the true value of having the population trained in, and performing, immediate and effective CPR. Urgent changes are indeed needed in CPR guidelines, training and practice.

Hyperventilation During CPR
     O'Neill JF, Deakin CD. Do we hyperventilate cardiac arrest patients? Resuscitation 73(1):82-;5, Apr 2007. Abstract: Hyperventilation during cardiopulmonary resuscitation is detrimental to survival. Several clinical studies of ventilation during hospital and out-of-hospital cardiac arrest have demonstrated respiratory rates far in excess of the 10/minute (-1) recommended by the European Resuscitation Council. [Authors] observed detailed ventilation variables prospectively during manual ventilation of 12 cardiac arrest patients treated in the emergency department of a U.K. hospital. Methods-Adult cardiac arrest patients were treated according to ERC guidelines. Ventilation was provided using a self-inflating bag. A monitor was inserted into the ventilation circuit at the beginning of the resuscitation from which ventilation data were downloaded to a laptop. Results-Data were collected from 12 patients (seven male; age 47-;82 years). The maximum respiratory rate was 9-;41 breaths per minute (median 26). The median tidal volume was 619 ml (374-;923 ml), and the median respiratory rate was 21/minute (-1) (7-;37 [-1]). The corresponding median minute volume was 13.0 l/min. (4.6-;21.3 [-1]). Median peak inspiratory pressures were 60.6 cm H2O (range 46-;106). Airway pressure was positive for 95.3% of the respiratory cycle (range 87.9%-;100%). Conclusions-Hyperventilation was common, mostly through high respiratory rates rather than excessive tidal volumes. This is the first study to document tidal volumes and airway pressures during resuscitation. The persistently high airway pressures are likely to have a detrimental effect on blood flow during CPR. Guidelines on respiratory rates are well known, but it would appear that in practice, they are not being observed.

     Comment: Eventually in cardiac arrest, after the first few minutes, ventilations can continue to supply oxygen during CPR. However, ventilations can harm as well, by increasing intrathoracic pressures and forcing blood out of the chest, thereby reducing blood circulation. The recommended rate of ventilation during CPR is 8-;10/minute and the volume (with oxygen) only 500-;600 ml-less than needed for most manikins to show a chest rise. We all know that ventilation rates and volumes usually far exceed these guidelines. EMS systems should begin to evaluate and train all providers to decrease the rate and reduce the volume of ventilations. It is not a simple task-it seems s-o-o-o sl-o-o-ow (and shallow)-but it's important to good patient care.

Angelo Salvucci, Jr., MD, FACEP, is an emergency physician and medical director for the Santa Barbara County and Ventura County (CA) EMS Agencies, and chair of the California Commission on EMS.