Chest compression and ventilation rates during cardiopulmonary resuscitation: the effects of audible tone guidance.

OBJECTIVES: To determine: 1) whether chest compressions during CPR are being performed according to American Heart Association (AHA) guidelines during cardiac arrest; and 2) the effect of an audio prompt to guide chest compressions on compliance with AHA guidelines and hemodynamic parameters associated with successful resuscitation. METHODS: An observational clinical report and laboratory study was conducted. A research observer responded to a convenience sample of cardiac arrests within a 300-bed hospital and counted the rate of chest compressions and ventilations during CPR. To evaluate the effect of an audio prompt on CPR, health care providers performed chest compression without guidance using a porcine cardiac arrest model for 1 minute, followed by a second minute in which audio guidance was added. Chest compression rates, arterial and venous blood pressures, end-tidal CO2 (ETCO2) levels, and coronary perfusion pressures were measured and compared for the two periods. RESULTS: Twelve in-hospital cardiac arrests were observed in the clinical part of the study. Only two of 12 patients had chest compressions performed within AHA guidelines. No patient had respirations performed within AHA guidelines. In the laboratory, 41 volunteers were tested, with 66% performing chest compressions outside the AHA standards for compression rate without audible tone guidance. With guided chest compressions, the mean (+/- SD) chest compression rate increased from 74 +/- 22 to 100 +/- 3/min (p < 0.01). End-tidal CO2 levels increased from 15 +/- 7 to 17 +/- 7 torr (p < 0.01). Coronary perfusion pressure increased minimally with audible tone-guided chest compressions. CONCLUSIONS: The majority of Basic Cardiac Life Support--certified health care professionals did not perform CPR according to AHA-recommended guidelines. The use of audible tones to guide chest compression resulted in significantly higher chest compression rates and ETCO2 levels.

Bystander cardiopulmonary resuscitation. Concerns about mouth-to-mouth contact.

BACKGROUND: Bystander cardiopulmonary resuscitation (CPR) is performed on only a small percentage of patients who suffer cardiac arrest. We conducted a study to elucidate attitudes toward and potential obstacles to performance of bystander CPR. METHODS: Attitude survey of 975 people on the University Heart Center, University of Arizona, Tucson, mailing list. Participants were asked about their willingness to perform CPR under four conditions, with varying relationships (stranger vs relative or friend) and CPR techniques (chest compressions plus mouth-to-mouth ventilation [CC+V] vs chest compressions alone [CC]). RESULTS: Participants rated willingness to perform CPR and concern about disease transmission. Both relationship and CPR technique affected willingness to respond. Only 15% would "definitely" provide CC+V with strangers compared with 68% who would "definitely" perform CC. Even with relatives or friends, only 74% would "definitely" provide CC+V compared with 88% who would "definitely" provide CC. Eighty-two percent of participants were at least "moderately" concerned about disease transmission. CONCLUSION: Concerns regarding mouth-to-mouth ventilation appear to create substantial barriers to performance of bystander CPR. Intensified educational efforts and investigations of new approaches to bystander CPR are warranted.

Efficacy of audio-prompted rate guidance in improving resuscitator performance of cardiopulmonary resuscitation on children.

OBJECTIVE: To evaluate the effect of audio-prompted rate guidance during chest compressions on the performance of cardiopulmonary resuscitation (CPR) on children. METHODS: This 24-month prospective study occurred in the pediatric intensive care units of a university hospital and a children's hospital. Intubated children with nontraumatic cardiac arrest were eligible. After placement of an infrared capnometer between the endotracheal tube and resuscitation bag, an audiotape instructed the resuscitator to perform chest compressions at 100 per minute or 140 per minute for one minute, followed by another minute at the other rate. End-tidal carbon dioxide partial pressure (PETCO2) was recorded prior to audiotape instruction and after one minute of CPR at each rate. RESULTS: Six patients, two boys and four girls, with a mean age of 15 +/- 13 months (range 2-36 months) were studied. All had asystole or pulseless electrical activity. CPR was provided for 14 +/- 9 minutes prior to institution of the study protocol. PETCO2 at 140/min was higher than at baseline (12 +/- 7 torr verus 4 +/- 3 torr, p < 0.05). There was a trend towards higher PETCO2s at 100/min compared with baseline (11 +/- 12 torr versus 4 +/- 3 torr, p = 0.08). PETCO2s did not differ at 100/min compared with 140/min. CONCLUSIONS: In support of prior adult and animal investigations suggesting that basic CPRR is often performed poorly and at inappropriately slow rates, audio- prompted rate guidance during CPR in children resulted in higher PETCO2, suggesting improved CPR performance.

Lipid-lowering drugs.

Controlling hyperlipidemia is an important aspect in the treatment and prevention of coronary artery disease. This article provides the clinician with a general reference for currently used lipid-lowering agents. Lipoproteins present in the plasma are defined and a brief overview of their functions is presented. Normal lipid uptake from the intestine and normal lipid metabolism are discussed to provide a basis for an understanding of the pharmaceutical treatment of hyperlipidemia. Guidelines are reviewed for interpreting lipid profiles according to the National Cholesterol Education Program. An evaluation of the agents currently used to treat hyperlipidemia is included. Lipid-lowering agents cause alterations in liver function; therefore, patients taking these medications are monitored closely. Patient teaching, including adverse effects of the medications, diet therapy and other alterable risk factors, is also reviewed.

Oxygenation and ventilation during cardiopulmonary resuscitation utilizing continuous oxygen delivery via a modified pharyngeal-tracheal lumened airway.

Use of continuous transtracheal oxygen delivery systems combined with rhythmic chest compressions can provide excellent oxygenation and ventilation during cardiopulmonary resuscitation. However, occasional displacement of the transtracheal catheter results in life-threatening pneumomediastinal complications. We investigated using the pharyngeal lumen of a pharyngeal-tracheal lumened airway (PtL) as an alternative delivery system for continuous oxygen flow in 21 large mongrel dogs. Excellent ventilation was possible in anesthetized, apneic, and paralyzed dogs in normal sinus rhythm from the "bellows" effect of chest compressions. The hypercapnia and respiratory acidemia resulting from 5 min of complete apnea in ten dogs during normal sinus rhythm was readily corrected (p less than 0.01). In an additional 11 dogs, external chest compressions were performed and oxygen was delivered continuously via the PtL during 20 min of ventricular fibrillation. During this period of cardiac arrest, pH declined (7.38 +/- 0.01 vs 7.19 +/- 0.02; p less than 0.01), but PaCO2 (35 +/- 1 vs 38 +/- 3 mm Hg) and PaO2 (67 +/- 2 vs 68 +/- 3 mm Hg) were not significantly different from prearrest values. Successful resuscitation was achieved in 8 of 11 (73 percent) animals, which is similar to the results in historical controls with endotracheal intubation. No pneumomediastinal complications were seen with use of the PtL. We conclude that using the pharyngeal lumen of the PtL for continuous delivery of oxygen combined with external chest compressions can provide a safe and effective mode of oxygenation and ventilation during cardiac arrest.

A study of chest compression rates during cardiopulmonary resuscitation in humans. The importance of rate-directed chest compressions.

A prospective, cross-over trial was performed comparing two different rates of precordial compression using end-tidal carbon dioxide as an indicator of the efficacy of cardiopulmonary resuscitation in 23 adult patients. A second purpose of this study was to determine the effect of audio-prompted, rate-directed chest compressions on the end-tidal carbon dioxide concentrations during cardiopulmonary resuscitation. Patients with cardiac arrest received external chest compressions, initially in the usual fashion without rate direction and then with rhythmic audiotones for rate direction at either 80 compressions per minute or 120 compressions per minute. Nineteen of 23 patients had higher end-tidal carbon dioxide levels at the compression rate of 120 per minute. The mean end-tidal carbon dioxide level during compressions of 120 per minute was 15.0 +/- 1.8 mm Hg, slightly but significantly higher than the mean level of 13.0 +/- 1.8 mm Hg at a compression rate of 80 per minute. However, end-tidal carbon dioxide levels increased rather dramatically when audiotones were used to guide the rate of chest compressions. Mean end-tidal carbon dioxide concentration was 8.7 +/- 1.2 mm Hg during standard cardiopulmonary resuscitation immediately before audio-prompted, rate-directed chest compression and increased to 14.0 +/- 1.3 mm Hg after the first 60 seconds of audible tones directing compressions. Using end-tidal carbon dioxide as an indicator of cardiopulmonary resuscitation efficacy, we conclude that audible rate guidance during chest compressions may improve cardiopulmonary resuscitation performance.

End-tidal carbon dioxide monitoring during cardiopulmonary resuscitation. A prognostic indicator for survival.

The effectiveness of ongoing cardiopulmonary resuscitation efforts is difficult to evaluate. Recent studies suggest that carbon dioxide excretion may be a useful noninvasive indicator of resuscitation from cardiac arrest. A prospective clinical study was done to determine whether end-tidal carbon dioxide monitoring during cardiopulmonary resuscitation could be used as a prognostic indicator of resuscitation and survival. Thirty-five cardiac arrests in 34 patients were monitored with capnometry during cardiopulmonary resuscitation during a 1-year period. Nine patients who were successfully resuscitated had higher average end-tidal carbon dioxide partial pressures during cardiopulmonary resuscitation than 26 patients who could not be resuscitated (15 +/- 4 vs 7 +/- 5 mm Hg). The 3 patients who survived to leave the hospital had a higher average end-tidal carbon dioxide partial pressure than the 32 nonsurvivors (17 +/- 6 vs 8 +/- 5 mm Hg). All 9 patients who were successfully resuscitated had an average end-tidal carbon dioxide partial pressure of 10 mm Hg or greater. No patient with an average end-tidal carbon dioxide partial pressure of less than 10 mm Hg was resuscitated. Data from this prospective clinical trial indicate that findings from end-tidal carbon dioxide monitoring during cardiopulmonary resuscitation are correlated with resuscitation from and survival of cardiac arrest.