Simultaneous Sterno-Thoracic Cardiopulmonary Resuscitation Improves the Short-Term Survival Rate in Canine Cardiac Arrests

BACKGROUND AND OBJECTIVES: We previously reported that, compared with standard cardiopulmonary resuscitation(S-CPR), better hemodynamic effects could be achieved by simultaneous sterno-thoracic cardiopulamonary resuscitation(SST-CPR) in which we compressed the sternum and constricted the thorax circumferentially during the systolic period by using a device. This study was designed to assess whether SST-CPR, compared with S-CPR, improve the survival rate of dogs with cardiac arrest. SUBJECTS AND METHODS: Twenty-five mongrel dogs(19~31kg) were enrolled in this study. After four minutes of ventricular fibrillation induced by an AC current, animals were randomized to resuscitate with either S-CPR(n=13) or SST-CPR(n=12). Epinephrine(1mg) was injected into the right atrium every three minutes after the beginning of CPR. Defibrillation was attempted after 6 minutes of CPR. Standard advanced cardiac life support was started if defibrillation was not successful. RESULTS: SST-CPR resulted in significantly(p<0.001) higher systolic arterial pressure(91+/- 47 vs 47+/-24mmHg), diastolic pressure(43+/- 24 vs 17+/- 10mmHg), coronary perfusion pressure(35+/- 25 vs 13+/- 9mmHg), and end tidal CO2 tension(9+/- 4 vs 3+/- 2mmHg). Two of 13 animals(15%) resuscitated with S-CPR and six of 12 animals(50%) resuscitated with SST-CPR survived until 12 hours after cardiac arrest(p<0.05). CONCLUSION: SST-CPR, compared with S-CPR, improves the short-term survival rate in canine cardiac arrests.

Changes of Aortic Dimensions as an Evidence of Cardiac Pump Mechanism During Cardiopulmonary Resuscitation: Transesophageal Echocardiographic Observation

BACKGROUND: Although the cardiac pump mechanists and the thoracic pump mechanism have been suggested, the mechanism of blood flow generated by precordial compression in human remains controversial. We hypothesized that, during compression systole, the proximal descending thoracic aorta would be distended by forward blood flow if the heart acts as a pump, and be contacted or unchanged if increased intrathoracic pressure generates blood flow. METHODS: Fourteen patients with cardiac angst underwent transesophageal echocardiogaphy to verify the morphologic changes of the descending thoracic aorta during standard manual cardiopulmonary resuscitation. The aortic dimensions including cross sectional area and diameters at the end of compression and of relaxation were measured proximal to and at the maximal compressing site of the descending thoracic aorta. RESULTS: At the point of maximal compression, deformations of the descending thoracic aorta were observed during compression in all patients and ratio of the longest to shortest diameter of the aorta deceased during compression than relaxation(0.58+/-0.15 versus 0.81+/-0.11, p=0.001). Cross sectional area of the aorta at the maxim compression deceased during compression than relaxation(3.01+/-1.91 versus 7.26+/-14.70 cm2, p=0.035). Ratio of the longest to shortest diameter of the proximal descending thoracic aorta remained unchanged during compression and relaxation(1.0+/- 0.88 versus 1.0+/-0.9, p=0.345). Cross sectional area of the proximal descending thoracic aorta increased during compression than relaxation(4.81+/-2.86 versus 4.29+/-2.51 cm2, p=0.011). CONCLUSION: Distention of the proximal descending thoracic aorta and deformation of the aorta at the maximal compression during the compression systole suggests that the heart act as a pump during standard manual cardiopulmonary resucitation in human.

Hemodynamic Effects of Simultaneous Sterno-Thoracic Cardiopulmonary Resuscitation (SST-CPR) in Canine Model of Cardiac Arrest

BACKGROUND AND OBJECTIVES: No existing device for cardiopulmonary resuscitation(CPR)isdesignedto exploit both the "cardiac pump" and the "thoracic pump" simultaneously. This study was designed to assess the hemodynamic effects of simultaneous sterno-thoracic CPR (SST-CPR) vs. standard CPR (S-CPR) using a mechanical resuscitator in a canine model of cardiac arrest. DEVICE DESCRIPTION: We have built a device that depresses the sternum and circumferentially constricts the thorax simultaneously. This device has two components. The first component is a piston, which depresses the sternum. The second is a circumferential strap that constricts the thorax as the piston is pushed down on the sternum. MATERIALS AND METHODS: Twelve domestic dogs were enrolled in this study. After catheterizations to measure pressures from the aorta and the right atrium, ventricular fibrillation was induced by passing AC current to the right ventricle. After 4 minutes of cardiac arrest, S-CPR and SST-CPR were performed alternatively. Aortic pressure, right atrial pressure, cardiac output, and end tidal CO2 were measured while each method of CPR was performing. RESULTS: SST-CPR resulted in significantly higher mean arterial pressure than S-CPR (68.9+/-16.1 vs 30.5+/-10.0 mmHg, p<0.01). SST-CPR could generate higher coronary perfusion pressure than S-CPR (47.0+/-11.4 vs 17.3+/-8.9 mmHg, p<0.01). End tidal CO2 tension was also higher during SST-CPR than S-CPR (11.6+/-6.1 vs 2.17+/-3.3 mmHg, p<0.01). CONCLUSION: Simultaneous sternothoracic cardiopulmonary resuscitation is a new method of cardiopulmonary resuscitation, which can generate better hemodynamic effects than standard cardiopulmonary resuscitation.

Hemodynamic Effects of Simultaneous Sterno-Thoracic Cardiopulmonary Resuscitation (SST-CPR) in Canine Model of Cardiac Arrest

BACKGROUND AND OBJECTIVES: No existing device for cardiopulmonary resuscitation(CPR)isdesignedto exploit both the "cardiac pump" and the "thoracic pump" simultaneously. This study was designed to assess the hemodynamic effects of simultaneous sterno-thoracic CPR (SST-CPR) vs. standard CPR (S-CPR) using a mechanical resuscitator in a canine model of cardiac arrest. DEVICE DESCRIPTION: We have built a device that depresses the sternum and circumferentially constricts the thorax simultaneously. This device has two components. The first component is a piston, which depresses the sternum. The second is a circumferential strap that constricts the thorax as the piston is pushed down on the sternum. MATERIALS AND METHODS: Twelve domestic dogs were enrolled in this study. After catheterizations to measure pressures from the aorta and the right atrium, ventricular fibrillation was induced by passing AC current to the right ventricle. After 4 minutes of cardiac arrest, S-CPR and SST-CPR were performed alternatively. Aortic pressure, right atrial pressure, cardiac output, and end tidal CO2 were measured while each method of CPR was performing. RESULTS: SST-CPR resulted in significantly higher mean arterial pressure than S-CPR (68.9+/-16.1 vs 30.5+/-10.0 mmHg, p<0.01). SST-CPR could generate higher coronary perfusion pressure than S-CPR (47.0+/-11.4 vs 17.3+/-8.9 mmHg, p<0.01). End tidal CO2 tension was also higher during SST-CPR than S-CPR (11.6+/-6.1 vs 2.17+/-3.3 mmHg, p<0.01). CONCLUSION: Simultaneous sternothoracic cardiopulmonary resuscitation is a new method of cardiopulmonary resuscitation, which can generate better hemodynamic effects than standard cardiopulmonary resuscitation.

Role of Transesophageal Echocardiography in Differential Diagnosis of The Cause of Cardiac Arrest During The Secondary Survey of Advanced Cardiac Life Support

BACKGROUND: During the secondary survey of advanced cardiac life support (ACLS), differential diagnosis to seek the cause of cardiac arrest is an important step in patient who failed to restore spontaneous circulation after the primary survey and resuscitation. This study was to evaluate the role of transesophageal echocardiography (TEE) for assessing the cause of cardiac arrest during the secondary survey of ACLS. METHOD: We performed biplane TEE during cardiopulmonary resuscitation (CPR) in 52 consecutive patients (31 male, 21 female, mean age: 58 years old) with cardiac arrest who failed to restore spontaneous circulation after the primary survey and resuscitation attempt. Initial presenting ECG rhythm was ventricular fibrillation in 7, asystole in 25, and pulseless electrical activity in 20 patients. TEE was performed immediately if spontaneous circulation was not restored after the primary survey and resuscitation. Possible causes of cardiac arrest were detected in 23 patients (44%) by TEE. Positive findings were observed in 3 (43%) of 7 patients with ventricular fibrillation, 12 (48%) of 25 patients with asystole, and 8 (40%) of 20 patients with pulseless electrical activity. TEE findings were as followings : pericardial effusion in 10, aortic dissection in 5, occlusion of mitral orifice by a thrombus or a mass in 2, main pulmonary artery thrombus in 2, thrombotic occlusion of the prosthetic valve in 1, hypertrophic cardiomyopathy in 1, and aortic stenosis in 1. Interventions including pericardiocentesis (n=10) and emergency thoracotomy (n=1) were attempted during resuscitation. Spontaneous circulation was restored in 16 patients (31%). One patient was discharged alive. CONCLUSION: TEE is an useful diagnostic tool to identify the cause of cardiac arrest during the secondary survey of ACLS.