Open- versus closed-chest cardiac compressions in a canine model of pediatric cardiopulmonary resuscitation

2024 RECOVER Guidelines: Advanced Life Support. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR

OBJECTIVE

To systematically review the evidence and devise clinical recommendations on advanced life support (ALS) in dogs and cats and to identify critical knowledge gaps.

DESIGN

Standardized, systematic evaluation of literature pertinent to ALS following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by Evidence Evaluators, and findings were reconciled by ALS Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk:benefit relationship, and clinical feasibility. This process was implemented using an Evidence Profile Worksheet for each question that included an introduction, consensus on science, treatment recommendations, justification for these recommendations, and important knowledge gaps. A draft of these worksheets was distributed to veterinary professionals for comment for 4 weeks prior to finalization.

SETTING

Transdisciplinary, international collaboration in university, specialty, and emergency practice.

RESULTS

Seventeen questions pertaining to vascular access, vasopressors in shockable and nonshockable rhythms, anticholinergics, defibrillation, antiarrhythmics, and adjunct drug therapy as well as open-chest CPR were reviewed. Of the 33 treatment recommendations formulated, 6 recommendations addressed the management of patients with nonshockable arrest rhythms, 10 addressed shockable rhythms, and 6 provided guidance on open-chest CPR. We recommend against high-dose epinephrine even after prolonged CPR and suggest that atropine, when indicated, is used only once. In animals with a shockable rhythm in which initial defibrillation was unsuccessful, we recommend doubling the defibrillator dose once and suggest vasopressin (or epinephrine if vasopressin is not available), esmolol, lidocaine in dogs, and/or amiodarone in cats.

CONCLUSIONS

These updated RECOVER ALS guidelines clarify the approach to refractory shockable rhythms and prolonged CPR. Very low quality of evidence due to absence of clinical data in dogs and cats continues to compromise the certainty with which recommendations can be made.

Effects of Left Ventricular Versus Traditional Chest Compressions in a Traumatic Pulseless Electrical Activity Model

BACKGROUND

Prehospital cardiopulmonary resuscitation has commonly been considered ineffective in traumatic cardiopulmonary arrest because traditional chest compressions do not produce substantial cardiac output. However, recent evidence suggests that chest compressions located over the left ventricle (LV) produce greater hemodynamics when compared to traditional compressions. We hypothesized that chest compressions located directly over the LV would result in an increase in return of spontaneous circulation (ROSC) and hemodynamic variables, when compared to traditional chest compressions, in a swine model of traumatic pulseless electrical activity (PEA).

METHODS

Transthoracic echocardiography was used to mark the location of the aortic root (traditional compressions) and the center of the LV on animals (n = 34) that were randomized to receive chest compressions in one of the two locations. Animals were hemorrhaged to mean arterial pressure <20 to simulate traumatic PEA. After 5 minutes of PEA, basic life support (BLS) with mechanical cardiopulmonary resuscitation was initiated and performed for 10 minutes followed by advanced life support for an additional 10 minutes. Hemodynamic variables were averaged over the final 2 minutes of BLS and advanced life support periods.

RESULTS

Six of the LV group (35%) achieved ROSC compared to eight of the traditional group (47%) (P = .73). There was an increase in aortic systolic blood pressure (P < .01), right atrial systolic blood pressure (P < .01), and right atrial diastolic blood pressure (P = .02) at the end of BLS in the LV group compared to the traditional group.

CONCLUSIONS

In our swine model of traumatic PEA, chest compressions performed directly over the LV improved blood pressures during BLS but not ROSC.

The Effect of Chest Compression Location and Aortic Perfusion in a Traumatic Arrest Model

BACKGROUND

Recent evidence demonstrates that closed chest compressions directly over the left ventricle (LV) in a traumatic cardiac arrest (TCA) model improve hemodynamics and return of spontaneous circulation (ROSC) when compared to traditional compressions. Selective aortic arch perfusion (SAAP) also improves hemodynamics and controls hemorrhage in TCA. We hypothesized that chest compressions located over the LV would result in improved hemodynamics and ROSC in a swine model of TCA using SAAP.

MATERIALS AND METHODS

Transthoracic echo was used to mark the location of the aortic root (Traditional location) and the center of the LV on animals (n = 24), which were randomized to receive chest compressions in one of the two locations. After hemorrhage, ventricular fibrillation (VF) was induced to simulate TCA. After a period of 10 min of VF, basic life support (BLS) with mechanical CPR was initiated and performed for 10 min, followed by advanced life support (ALS) for an additional 10 min. SAAP balloons were inflated at min 6 of BLS. Hemodynamic variables were averaged over the final 2 min of the BLS and ALS periods. Survival was compared between this SAAP cohort and a control group without SAAP (No-SAAP) (n = 26).

RESULTS

There was no significant difference in ROSC between the two SAAP groups (P = 0.67). There was no ROSC difference between SAAP and No-SAAP (P = 0.74).

CONCLUSIONS

There was no difference in ROSC between LV and Traditional compressions when SAAP was used in this swine model of TCA. SAAP did not confer a survival benefit compared to historical controls.

The Effect of Chest Compression Location and Occlusion of the Aorta in a Traumatic Arrest Model

BACKGROUND

Recent evidence demonstrates that closed chest compressions directly over the left ventricle (LV) in a traumatic cardiac arrest (TCA) model improve hemodynamics and return of spontaneous circulation (ROSC) when compared with traditional compressions. Resuscitative endovascular balloon occlusion of the aorta (REBOA) also improves hemodynamics and controls hemorrhage in TCA. We hypothesized that chest compressions located over the LV would result in improved hemodynamics and ROSC in a swine model of TCA using REBOA.

MATERIALS AND METHODS

Transthoracic echo was used to mark the location of the aortic root (traditional location) and the center of the LV on animals (n = 26), which were randomized to receive chest compressions in one of the two locations. After hemorrhage, ventricular fibrillation was induced to simulate TCA. After a period of 10 min of ventricular fibrillation, basic life support (BLS) with mechanical cardiopulmonary resuscitation was initiated and performed for 10 min followed by advanced life support for an additional 10 min. REBOA balloons were inflated at 6 min into BLS. Hemodynamic variables were averaged during the final 2 min of the BLS and advanced life support periods. Survival was compared between this REBOA cohort and a control group without REBOA (no-REBOA cohort) (n = 26).

RESULTS

There was no significant difference in ROSC between the two REBOA groups (P = 0.24). Survival was higher with REBOA group versus no-REBOA group (P = 0.02).

CONCLUSIONS

There was no difference in ROSC between LV and traditional compressions when REBOA was used in this swine model of TCA. REBOA conferred a survival benefit regardless of compression location.

Survival and Cardiopulmonary Resuscitation Hemodynamics Following Cardiac Arrest in Children With Surgical Compared to Medical Heart Disease

OBJECTIVES

To assess the association of diastolic blood pressure cutoffs (≥ 25 mm Hg in infants and ≥ 30 mm Hg in children) during cardiopulmonary resuscitation with return of spontaneous circulation and survival in surgical cardiac versus medical cardiac patients. Secondarily, we assessed whether these diastolic blood pressure targets were feasible to achieve and associated with outcome in physiology unique to congenital heart disease (single ventricle infants, open chest), and influenced outcomes when extracorporeal cardiopulmonary resuscitation was deployed.

DESIGN

Multicenter, prospective, observational cohort analysis.

SETTING

Tertiary PICU and cardiac ICUs within the Collaborative Pediatric Critical Care Research Network.

PATIENTS

Patients with invasive arterial catheters during cardiopulmonary resuscitation and surgical cardiac or medical cardiac illness category.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic waveforms during cardiopulmonary resuscitation were analyzed on 113 patients, 88 surgical cardiac and 25 medical cardiac. A similar percent of surgical cardiac (51/88; 58%) and medical cardiac (17/25; 68%) patients reached the diastolic blood pressure targets (p = 0.488). Achievement of diastolic blood pressure target was associated with improved survival to hospital discharge in surgical cardiac patients (p = 0.018), but not medical cardiac patients (p = 0.359). Fifty-three percent (16/30) of patients with single ventricles attained the target diastolic blood pressure. In patients with an open chest at the start of chest compressions, 11 of 20 (55%) attained the target diastolic blood pressure. In the 33 extracorporeal cardiopulmonary resuscitation patients, 16 patients (48%) met the diastolic blood pressure target with no difference between survivors and nonsurvivors (p = 0.296).

CONCLUSIONS

During resuscitation in an ICU, with invasive monitoring in place, diastolic blood pressure targets of greater than or equal to 25 mm Hg in infants and greater than or equal to 30 mm Hg in children can be achieved in patients with both surgical and medical heart disease. Achievement of diastolic blood pressure target was associated with improved survival to hospital discharge in surgical cardiac patients, but not medical cardiac patients. Diastolic blood pressure targets were feasible to achieve in 1) single ventricle patients, 2) open chest physiology, and 3) extracorporeal cardiopulmonary resuscitation patients.

Left ventricular compressions improve return of spontaneous circulation and hemodynamics in a swine model of traumatic cardiopulmonary arrest

BACKGROUND

Prehospital cardiopulmonary resuscitation, including closed chest compressions, has commonly been considered ineffective in traumatic cardiopulmonary arrest (TCPA) because traditional chest compressions do not produce substantial cardiac output. However, recent evidence suggests that chest compressions located over the left ventricle (LV) produce greater hemodynamics when compared to traditional compressions. We hypothesized that chest compressions located directly over the LV would improve return of spontaneous circulation (ROSC) and hemodynamics when compared with traditional chest compressions, in a swine model of TCPA.

METHODS

Transthoracic echocardiography was used to mark the location of the aortic root (traditional compressions), and the center of the LV on animals (n = 26) which were randomized to receive chest compressions in one of the two locations. After hemorrhage, ventricular fibrillation was induced. After 10 minutes of ventricular fibrillation, basic life support (BLS) with mechanical cardiopulmonary resuscitation was initiated and performed for 10 minutes followed by advanced life support (ALS) for an additional 10 minutes. During BLS, the area of maximal compression was verified using transesophageal echocardiography. Hemodynamic variables were averaged over the final 2 minutes of the BLS and ALS periods.

RESULTS

Five (38%) of the LV group achieved ROSC compared with zero of the aortic root group (p = 0.04). Additionally, there was an increase in aortic systolic blood pressure (SBP), aortic diastolic blood pressure (DBP) and coronary perfusion pressure (CPP) at the end of both the BLS (95% confidence interval, SBP, -49 to -21; DBP, -14 to -5.6; and CPP, -15 to -7.4) and ALS (95% confidence interval: SBP, -66 to -21; DBP, -49 to -6.8; and CPP, -51 to -7.5) resuscitation periods among the LV group.

CONCLUSION

In our swine model of TCPA, chest compressions performed directly over the LV improved ROSC and hemodynamics when compared with traditional chest compressions.

Open-chest cardiopulmonary resuscitation: past, present and future

Out-of-hospital cardiac arrests account for approximately 1000 sudden cardiac deaths per day in the United States. Since its introduction in 1960 closed-chest cardiac massage (CCCM) often takes place as an attempt at resuscitation, although its survival rates are low. Other resuscitation techniques are available to physicians such as open-chest cardiopulmonary resuscitation (OCCPR). OCCPR has been shown by several scientists to be hemodynamically superior to CCCM as it increases arterial pressures, cardiac output, coronary perfusion pressures, return of spontaneous circulation and cerebral blood flow. Improved neurological and cardiovascular outcome and an increase in survival rate compared to CCCM have been described. Timing is one of the key variables in determining patient outcome when performing OCCPR. The American Heart Association in association with the International Liaison Committee (ILCOR) has specific indications for the use of OCCPR. Some investigators recommend starting OCCPR in out-of-hospital cardiac arrests on arrival at the scene instead of CCCM. Surprisingly, the incidence of infectious complications after thoracotomy in an unprepared chest is low. The vast majority of the patients' families accept OCCPR as a therapeutic choice for cardiac arrests and it has been showed to be economically viable. This paper reviews some of the basic and advanced concepts of this evolving technique.

Pediatric cardiopulmonary-cerebral resuscitation: an overview and future directions

The evolving understanding of pathophysiologic events during and after pediatric cardiac arrest has not yet resulted in significantly improved outcome. Exciting breakthroughs in basic and applied science laboratories are, however, on the immediate horizon for study in specific subpopulations of cardiac arrest victims. Strategically focusing therapies to specific phases of cardiac arrest and resuscitation and evolving pathophysiologic events offers great promise that critical care interventions will lead the way to more successful cardiopulmonary and cerebral resuscitation in children.

Insertion of the minimally invasive direct cardiac massage device (MIDCM): training on human cadavers

OBJECTIVE

Recently, a new device for minimally invasive direct cardiac massage (MIDCM) has been developed. In animal models of cardiopulmonary resuscitation MIDCM has been shown to provide better organ perfusion than external chest compressions (ECC) massage. Since this device has been developed to improve cardiopulmonary resuscitation in humans, its use must be simple. Thus, we measured the time required for the insertion of the MIDCM device on human cadavers.

DESIGN

After a 1 h theoretical course, physicians and surgeons were asked to use the MIDCM device on human cadavers. We measured the time from the cutaneous incision to the first direct cardiac compression.

MAIN RESULTS

The mean time required for the insertion of the MIDCM device was 16+/-11 s (range 8-58 s). The insertion time required for each group of physicians were as follows, 15+/-8 s for anaesthesiologists (range 8-28 s), 11+/-2 s for cardiac surgeons (range 9-15 s), 42+/-14 s for cardiologists (range 27-58 s), and 12+/-4 s for intensive care physicians (range 8-18). All participants compared the insertion of the MIDCM device favorably with the insertion of a chest drain.

CONCLUSION

The MIDCM device can be placed in a few seconds in human cadavers by physicians familiar with chest drain insertion. Theoretical course and training with the device may be useful especially for those who are not familiar with chest drain insertion.

Minimally invasive direct cardiac massage versus closed-chest cardiopulmonary resuscitation in a porcine model of prolonged ventricular fibrillation cardiac arrest

Open chest cardiac massage has been shown to be superior to closed-chest cardiopulmonary resuscitation for both hemodynamics produced during resuscitation and ultimate resuscitation success. The inexperience of many rescuers with emergency thoracotomy, along with the associated morbidity contributes to the continued reluctance in the use of invasive cardiopulmonary resuscitation techniques. A device has been developed for performing 'minimally invasive' direct cardiac massage. This technique was compared to standard closed-chest CPR for resuscitation results in 20 swine during prolonged ventricular fibrillation cardiac arrest. Minimally invasive direct cardiac massage was superior to closed-chest CPR for return of spontaneous circulation (7/10 vs. 2/10; P<0.02) and coronary perfusion pressure at 30 min of CPR (17+/-9 vs. 6+/-6 mmHg; P<0.05). No significant injuries altering outcome were found with the invasive device. Throughout most of the time course of the study no significant differences in end-tidal expired carbon dioxide levels were noted. Nor were there any differences in 24-h survival. Improvements in assuring proper placement of the device on the epicardium should make this technique a potent advanced cardiac life support adjunct.

Is emergency open chest cardiopulmonary resuscitation accepted by patients' families?

Emergency open chest cardiopulmonary resuscitation (OCCPR) is sometimes performed on patients with cardiopulmonary arrest (CPA), especially those resulting from trauma. Since OCCPR is frequently carried out without the permission of patients' families, we surveyed the opinions of the families. A total of 1058 CPA patients were transferred to our department during the last 15 years. We sent questionnaires individually to the families of these patients to ask their opinions about OCCPR. The questionnaire provided the six questions allowing multiple answers; (1) Do you unconditionally agree with OCCPR? (2) Do you agree with OCCPR in children? (3) Do you agree with OCCPR in elderly patients? (4) Do you agree with OCCPR without permission from patient's families? (5) Do you entrust OCCPR to the doctors in charge? and (6) others. The questionnaire reached 846 families, of which 277 (32.7%) responded. The percentage response to each question was (1) 70.2, (2) 5.8, (3) 21.8, (4) 7.1, (5) 4.2 and (6) 5.0%. The younger the age of the responders the more they agreed with OCCPR. All the responders less than 30 years old agreed with the procedure. Of the 277 families, 95 had CPA patients treated with OCCPR. This group of families responded to six questions at the following rates: (1) 79.5, (2) 6.0, (3) 13.3, (4) 2. 4, (5) 4.8 and (6) 4.8%, suggesting that families with OCCPR patients are more cooperative to our treatment than those with non-OCCPR patients. The results of this study suggest that OCCPR in CPA patients is generally accepted by the patients' families, especially by young generations, although post-OCCPR careful explanation to patients' families is still indispensable.

New thoughts on cardiopulmonary resuscitation

The results of cardiopulmonary resuscitation (CPR) have been distressingly poor when one considers the amount of research in this field since 1960. Accordingly, some improvements to present protocols have been suggested. Some of the suggestions can be applied by practicing veterinarians to increase the success rate for external chest massage. In addition, veterinarians are encouraged to switch to internal cardiac massage early in the resuscitation period.

Additive impact of in-hospital cardiac arrest on the functioning of children with heart disease

OBJECTIVE

This study examined the impact of a sudden cardiac arrest (CA) on the neurodevelopmental and adaptive functioning of young children with congenital heart disease (CHD).

METHODOLOGY

Sixteen children with CHD who had sustained an in-hospital CA were compared with a medically similar group of children with CHD who had not incurred a CA. The contribution of CA, disease severity, and family socioeconomic status on the prediction of developmental outcome variables was evaluated.

RESULTS

Children in the CA group displayed more impairments in general cognitive, motor, and adaptive behavior functioning as well as greater disease severity as measured by a cumulative medical risk index. With respect to all children in the study, a higher socioeconomic status was related to higher scores on cognitive functioning, lower levels of child maladjustment, and lower levels of stress within the parent-child relationship. Although the occurrence of a CA alone did not contribute to the prediction of outcome measures, a significant interactional effect between CA and cumulative medical risk index was found. Specifically, among children who had incurred a CA, as disease severity increased, decrements in abilities were observed. Few significant correlations between specific CA-related variables (eg, length of CA) and outcome indices were found.

CONCLUSIONS

Results from this study indicate that the impact of cardiac arrest on neuropsychological functioning may be mediated by the child's overall disease severity. These findings have implications for the identification of CA survivors at greatest risk for developmental difficulties.

Mastering pediatric cardiopulmonary resuscitation

Premature and unexpected death, especially in children, is tragic and very unacceptable. Effective treatments for sudden death of pediatric patients continue to emerge. Modern cardiopulmonary resuscitation function began with the widespread introduction of closed-chest cardiac massage in 1960; however, despite 35 years of research and refinement, more than 90% of children who receive cardiopulmonary resuscitation do not survive. This article summarizes and expands on current treatment concepts for pediatric sudden death. Emphasis is placed on procedures and techniques that likely are accessible in most medical centers caring for critically ill and injured children.

Extracorporeal circulation as an alternative to open-chest cardiac compression for cardiac resuscitation

Open-chest direct cardiac compression represents a more potent but highly invasive option for cardiac resuscitation when conventional techniques of closed-chest cardiac resuscitation fail after prolonged cardiac arrest. We postulated that venoarterial extracorporeal circulation might be a more effective intervention with less trauma. In the setting of human cardiac resuscitation, however, controlled studies would be limited by strategic constraints. Accordingly, the effectiveness of open-chest cardiac compression was compared with that of extracorporeal circulation after a 15-min interval of untreated ventricular fibrillation in a porcine model of cardiac arrest. Sixteen domestic pigs were randomized to resuscitation by either peripheral venoarterial extracorporeal circulation or open-chest direct cardiac compression. During resuscitation, epinephrine was continuously infused into the right atrium, and defibrillation was attempted by transthoracic countershock at 2-min intervals. Systemic blood flows averaged 198 ml.kg-1.min-1 with extracorporeal circulation. This contrasted with direct cardiac compression, in which flows averaged only 40 ml.kg-1.min-1. Coronary perfusion pressure, the major determinant of resuscitability on the basis of earlier studies, was correspondingly lower (94 vs 29 mm Hg). Extracorporeal circulation, in conjunction with transthoracic DC countershock and epinephrine, successfully reestablished spontaneous circulation in each of eight animals after 15 min of untreated ventricular fibrillation. This contrasted with the outcome after open-chest cardiac compression, in which spontaneous circulation was reestablished in only four of eight animals (p = .038). We conclude that extracorporeal circulation is a more effective alternative to direct cardiac compression for cardiac resuscitation after protracted cardiac arrest.

Limitations of open-chest cardiac massage after prolonged, untreated cardiac arrest in dogs

STUDY OBJECTIVES

Open-chest cardiac massage is an effective method of resuscitation if instituted within 15 minutes of normothermic cardiac arrest that has failed to respond to ongoing closed-chest CPR efforts. The usefulness of invasive forms of CPR after various periods of untreated cardiac arrest is less certain. This study was performed to determine the effectiveness of open-chest resuscitation after prolonged periods of untreated cardiac arrest.

SETTING AND DESIGN

Prospective, controlled laboratory investigation using an animal model of cardiac arrest. Open-chest cardiac massage initially was compared to standard closed-chest compression CPR. The efficacy of open-chest CPR then was evaluated after ten and 40 minutes of untreated ventricular fibrillation.

TYPE OF PARTICIPANTS

Twenty mongrel dogs (24 +/- 1 kg).

MEASUREMENTS AND MAIN RESULTS

After 20 minutes of untreated ventricular fibrillation, open-chest resuscitation was significantly better than closed-chest efforts for the production of coronary perfusion pressure (58 +/- 14 vs 2 +/- 1 mm Hg; P less than .05) and initial resuscitation success (five of five vs one of five; P less than .03). Open-chest cardiac massage was equally effective for initial resuscitation if begun after ten or 20 minutes of untreated ventricular fibrillation (five of five vs five of five), but if untreated ventricular fibrillation continued for 40 minutes prior to instituting open-chest massage, no resuscitation benefit was found (none of five; P less than .005). There were marked differences in 24-hour survival depending on the length of time untreated cardiac arrest continued prior to instituting open-chest resuscitation efforts. After 20 minutes of ventricular fibrillation, initial resuscitation was successful with open-chest massage, but long-term survival was poor.

CONCLUSION

Open-chest cardiac massage did not produce long-term survival if untreated cardiac arrest persisted for 20 or more minutes prior to invasive resuscitation efforts.

High-dose epinephrine improves outcome from pediatric cardiac arrest

STUDY OBJECTIVE

Animal studies suggest that the standard dose of epinephrine (SDE) for treatment of cardiac arrest in human beings may be too low. We compared the outcome after SDE with that after high-dose epinephrine (HDE) in children with refractory cardiac arrest.

DESIGN

Prospective intervention versus historic control groups.

TYPE OF PARTICIPANTS

Two similar groups of 20 consecutive patients each (median ages, 2.5 and 3 years) with witnessed cardiac arrest who remained in arrest after at least two SDEs (0.01 mg/kg).

INTERVENTIONS

Treatment with an additional SDE versus HDE (0.2 mg/kg).

MEASUREMENTS AND MAIN RESULTS

The rates of return of spontaneous circulation and long-term survival were compared. Fourteen of the HDE group (70%) had return of spontaneous circulation, whereas none of the SDE group did (P less than .001). Eight children survived to discharge after HDE, and three were neurologically intact at follow-up. No significant toxicity from HDE was observed.

CONCLUSION

HDE provided a higher return of spontaneous circulation rate and a better long-term outcome than SDE in our series of pediatric cardiac arrest. HDE may warrant incorporation into standard resuscitation protocols at an early enough point to prevent irreversible brain injury.

Open-chest cardiac massage. The possible rebirth of an old procedure

Open-chest cardiac massage was widely and successfully used for many decades before its virtual abandonment 25 years ago. Both experimental evidence and basic physiologic evidence indicate that it has many advantages over closed-chest massage (especially increased cardiac output). Both resuscitation techniques have specific and unique advantages and disadvantages: They are not mutually exclusive. However, significant increases in rates of survival after cardiac arrest cannot be expected with variations of closed-chest cardiac massage and standard advanced life support services. Therefore, physicians must be willing to support controlled human studies that can definitively determine the proper role of each in resuscitation after cardiac arrest.

Effect of epinephrine on cerebral and myocardial perfusion in an infant animal preparation of cardiopulmonary resuscitation

We assessed the efficacy of conventional cardiopulmonary resuscitation (CPR) in 2-week-old piglets. We determined intrathoracic vascular pressures, cerebral (CBF) and myocardial blood flows (MBF), and cerebral oxygen uptake during conventional CPR in this infant animal preparation and contrasted these results with those of previous work on adult animals. We further examined the effects of the infusion of epinephrine on these pressures and flows and on cerebral oxygen uptake, which has not been previously evaluated in adult preparations. Conventional CPR was performed on pentobarbital-anesthetized piglets with a 20% sternal displacement with the use of a pneumatic piston compressor. Chest recoil was incomplete, leading to an 18% to 27% reduction in anteroposterior diameter during the relaxation phase. Aortic and right atrial pressures in excess of 80 mm Hg were generated. These pressures are greater than those generally obtained in adult animals with similar percent pulsatile displacements. CBF and MBF were also initially greater than those reported in adult animals undergoing conventional CPR. However, when CPR was prolonged beyond 20 min, aortic pressure fell and CBF and MBF declined to the near-zero levels seen in adult preparations. At 5 min of CPR, CBF and MBF were 24 +/- 7 and 27 +/- 7 ml . min-1 x 100 g-1 (50% and 17% of the values during cardiac arrest), respectively. With the continuous infusion of epinephrine (4 micrograms/kg/min) in another group of animals, MBF was significantly greater at 20 min of CPR and CBF and cerebral O2 uptake were greater at 35 min of CPR as a result of higher perfusion pressures.(ABSTRACT TRUNCATED AT 250 WORDS)