Chest Compressions Alone Best for Resuscitation in Cardiac Arrest Patients  CME/CE

News Author: Sue Hughes
CME Author: Désirée Lie, MD, MSEd

Disclosures

Release Date: March 20, 2007Valid for credit through March 20, 2008

Credits Available

 

Physicians - maximum of 0.25 AMA PRA Category 1 Credit(s)™ for physicians;
Family Physicians - up to 0.25 AAFP Prescribed credit(s) for physicians;
Nurses - 0.25 nursing contact hours (None of these credits is in the area of pharmacology)

 

from Heartwire — a professional news service of WebMD

March 20, 2007A study has shown that for bystander cardiopulmonary resuscitation (CPR), the use of chest compressions alone without mouth-to-mouth ventilation is the preferable method for reviving people who have had out-of-hospital cardiac arrest.

The study, published in the March 17 issue of The Lancet, found no evidence for any benefit from the addition of mouth-to-mouth ventilation to chest compressions and that certain groups of patients had better outcomes with chest compressions alone.

An accompanying editorial states, "This critically important finding ... should lead to changes in guidelines. Advocating, encouraging, and teaching chest-compression only for witnessed unexpected sudden collapse will dramatically increase bystander initiated resuscitation efforts and thereby give these patients a better chance of survival when emergency personnel arrive."

The study authors, led by Ken Nagao, MD, from the Surugadai Nihon University Hospital in Tokyo, Japan, note that although bystander CPR improves the likelihood of survival for people with cardiac arrest, it is attempted in less than one third of patients who collapse. They say that one of the major barriers to bystanders performing CPR is their reluctance to undertake mouth-to-mouth ventilation, partly because of fear of transmission of infectious diseases, and the complexity of the CPR technique as presently taught.

They point out that cardiac-only resuscitation is recommended if a rescuer is unwilling or unable to do mouth-to-mouth ventilation, but that this technique is not generally taught to the public, and few clinical studies have evaluated this approach.

They therefore conducted a prospective, multicenter, observational study of patients who had witnessed out-of-hospital cardiac arrest in which, on arrival at the scene, paramedics assessed the technique of bystander resuscitation. Of 4068 adult cardiac arrest patients included, 11% received cardiac-only resuscitation from bystanders, 18% received conventional CPR with both cardiac compression and mouth-to-mouth ventilation, and 72% received no bystander CPR.

Results showed that any resuscitation attempt was associated with a higher likelihood of having favorable neurologic outcomes at 30 days than no resuscitation.

Table 1. Proportion of Patients Achieving a Favorable Neurologic Outcome at 30 Days

Neurologic Outcome

Any Resuscitation Technique

No Bystander Resuscitation

P

Favorable outcome

5.0%

2.2%

< .0001

 

Source. Lancet. 2007;369:882-884, 920-926.

Although favorable neurologic outcomes did not differ between the cardiac-only resuscitation group and the conventional CPR group for the whole cohort (P = .1459), cardiac-only resuscitation resulted in a higher proportion of patients with favorable neurologic outcomes than conventional CPR in the subgroups of patients with apnea (about 90% of patients in this study), ventricular fibrillation, or tachycardia as initial cardiac rhythm, and in those in whom resuscitation was started within 4 minutes of collapse. Furthermore, there was no evidence for any benefit from the addition of mouth-to-mouth ventilation in any subgroup of patients.

Table 2. Proportion of Patients Achieving a Favorable Neurologic Outcome at 30 Days

Patients

Cardiac-Only Resuscitation

Conventional CPR

P

Patients with apnea

6.2%

3.1%

.0195

Patients with a shockable rhythm

19.4%

11.2%

.041

Patients in whom resuscitation started within 4 minutes

10.1%

5.1%

.0221

 

Source: Lancet. 2007;369:882-884, 920-926.

The authors suggest several reasons for their results. They cite previous studies that have suggested that ventilation is not essential during the initial 12 minutes of resuscitation, and note that time spent on mouth-to-mouth ventilation takes precious time away from chest compressions that support cerebral and coronary perfusion.

In the editorial, Gordon Ewy, MD, from the University of Arizona College of Medicine in Tucson, suggests more reasons why mouth-to-mouth ventilation may be unnecessary or even detrimental. He points out that during cardiac arrest, mouth-to-mouth or positive-pressure ventilation increases intrathoracic pressures, thereby reducing venous return to the chest, and reducing the already marginal coronary and cerebral blood flow during cardiac arrest and resuscitation, a situation which is made worse if forceful ventilation is given while the chest is being compressed. Dr. Ewy also notes that with the onset of ventricular-fibrillation induced arrest, the pulmonary veins, the left heart, and the entire arterial system are already filled with oxygenated blood, and in addition, many people who experience cardiac arrest will initially gasp and thereby provide physiologic ventilation.

Guidelines Should Be Changed

Dr. Ewy says a major flaw with the current, and all previous, guidelines for cardiac arrest is that they recommend the same approach of CPR for 2 entirely different clinical conditions: primary cardiac arrest where the arterial blood is well oxygenated at the time of the cardiac arrest and respiratory arrest when the arterial blood is so severely desaturated that it contributes to hypotension and secondary cardiac arrest.

"We should continue, for now, to follow the newer guidelines of assisted ventilations and chest compressions for respiratory arrest (such as in drowning or drug overdose), but the guidelines should promptly be changed to chest-compression alone for witnessed unexpected sudden collapse (a condition that is, in all probability, cardiac arrest)," he concludes.

Lancet. 2007;369:882-884, 920-926.

The complete contents of Heartwire, a professional news service of WebMD, can be found at www.theheart.org, a Web site for cardiovascular healthcare professionals.

Clinical Context

CPR consisting of chest compression plus mouth-to-mouth ventilation is a major element in the chain of survival for people with cardiac arrest. However, although bystander CPR improves the likelihood of survival, it is attempted in less than one third of patients who collapse, partly due to the reluctance of bystanders to undertake mouth-to-mouth ventilation. In CPR guidelines, according to the current authors, cardiac-only resuscitation by bystanders is recommended in dispatch-assisted resuscitation or if a rescuer is unwilling or unable to do mouth-to-mouth ventilation, but this technique is not generally known or taught to the public. One study has shown that cardiac-only resuscitation results in better survival without neurologic impairment.

This is a prospective, multicenter, observational study of bystander cardiac-only compared with conventional CPR and no resuscitation in patients who experienced out-of-hospital cardiac arrest.

Study Highlights

  • Included were patients with out-of-hospital cardiac arrest witnessed by bystanders who were subsequently transported to emergency hospitals by paramedics.
  • Excluded were patients younger than 18 years, with further cardiac arrest after arrival of paramedics, documented terminal illness, presence of a "do not resuscitate" order, or who received resuscitation without chest compression.
  • Cardiac arrest was defined as the cessation of cardiac mechanical activity, manifesting as unresponsiveness, apnea, or gasping breathing and absence of pulse.
  • The technique used during bystander resuscitation was classified as "cardiac-only," "conventional CPR," "pulmonary-only resuscitation," "unidentified technique," or "chest compression" not documented.
  • The person attempting bystander resuscitation was classified as a lay person with basic CPR training, a lay person assisted by a dispatcher, a lay person without training or assistance, or a medical worker.
  • Resuscitation attempts were documented by paramedics and attending physicians.
  • Primary endpoint was favorable neurologic outcome 30 days after cardiac arrest defined as a Glasgow-Pittsburgh cerebral performance category of 1 or 2.
  • Assessment of neurologic status was by blinded clinicians.
  • Secondary outcome was survival 30 days after cardiac arrest.
  • Included were 4068 bystander-witnessed cardiac arrests, of which 28% received bystander resuscitation.
  • 11% received cardiac-only, 18% received conventional CPR, and 72% did not receive any bystander resuscitation.
  • No patient was lost to follow-up.
  • There were no differences between groups for cause of cardiac arrest, location, initial cardiac rhythm, time of arrival of emergency services, or proportion with gasping breathing.
  • For the cardiac-only and conventional CPR groups, mean age was 68 years, two thirds were male, 55% occurred at home or in a residence and 35% outdoors, and 11% had gasping breathing.
  • The initial heart rhythm was asystole in 50% and pulseless ventricular tachycardia in 28%.
  • Average time from collapse to first bystander resuscitation attempt was 4 minutes and time from bystander attempt at resuscitation to first automated emergency defibrillation was 9 minutes.
  • Any resuscitation attempt was associated with higher frequencies of favorable neurologic outcome at 30 days, with a rate of 5% vs 2% (P < .001) for the resuscitation vs no resuscitation groups.
  • Better neurologic outcomes were associated with subgroups of patients with cardiac causes, with apnea, with ventricular fibrillation or tachycardia as initial cardiac rhythm, or who were resuscitated within 4 minutes of collapse.
  • Neurologic outcomes at 30 days were similar whether resuscitation was received from a lay or a medically trained person.
  • There was no benefit of the addition of mouth-to-mouth ventilation in any subgroup of patients.
  • The adjusted odds ratio for a favorable neurologic outcome after cardiac-only resuscitation was 2.2 in patients who received any resuscitation from bystanders.
  • Predictors of favorable neurologic outcome were younger age, shorter time between first bystander resuscitation, and automated emergency defibrillation analysis and ventricular fibrillation or tachycardia as initial cardiac rhythm.
  • The likelihood of favorable neurologic outcomes decreased in both bystander resuscitation groups for every 1-minute increment in time from first resuscitation attempt to first automated emergency defibrillation analysis.
  • The proportion of patients alive at 30 days and those alive at hospital admission were similar between the 2 bystander resuscitation groups.

Pearls for Practice

  • Predictors of favorable neurologic outcome in patients receiving bystander resuscitation for cardiac arrest are younger age, shorter time between first bystander resuscitation, and automated emergency defibrillation analysis and ventricular fibrillation or tachycardia as initial cardiac rhythm.
  • The use of cardiac-only resuscitation vs conventional CPR by bystanders is the preferred approach for better neurologic outcomes, especially in those with apnea, shockable rhythm, or short periods of untreated arrest.


1.

According to this study, all of the following are associated with better neurologic outcomes at 30 days after cardiac arrest with bystander resuscitation except:  (Required for credit)

 

Younger age

 

Male sex

 

Shorter time to automated emergency defibrillation analysis

 

Ventricular fibrillation as initial rhythm

2.

A bystander witnesses a cardiac arrest and attempts resuscitation. According to this study, which of the following options is most likely to be associated with more favorable neurologic outcome at 30 days after arrest?  (Required for credit)

 

Administration of CPR by a medically trained person

 

Use of conventional CPR

 

Use of cardiac-only resuscitation

 

Use of pulmonary-only resuscitation