Resuscitation. 2006 Jun;69(3):455-69. Epub 2006 Mar 24. Links Biophysics of cardiopulmonary resuscitation with periodic z-axis acceleration or abdominal compression at aortic resonant frequencies. Babbs CF. Department of Basic Medical Sciences, Purdue University, 1426 Lynn Hall, West Lafayette, IN 47907-1246, USA. [EMAIL PROTECTED] Periodic z-axis acceleration (pGz)-CPR involves an oscillating motion of a whole patient in the head-to-foot dimension on a mechanized table. The method is able to sustain blood flow and long-term survival during and after prolonged cardiac arrest in anesthetized pigs. However, the exact mechanism by which circulation of blood is created has remained unknown. OBJECTIVES: To explain the hemodynamic mechanism of pGz-CPR and to suggest some theoretically useful improvements. METHOD: Computer modeling using a hybrid analytical-numerical approach, based upon Newton's second law of motion for fluid columns in the aorta and vena cavae, Ohm's law for resistive flow through vascular beds, and a 10-compartment representation of the adult human circulation. This idealized 70-kg human model is exercised to explore the effects upon systemic perfusion pressure of whole body z-axis acceleration at frequencies ranging from 0.5 to 5 Hz. The results, in turn, suggested studies of abdominal compression at these frequencies. RESULTS AND CONCLUSIONS: Blood motion induced in great vessels by periodic z-axis acceleration causes systemic perfusion when cardiac valves are competent. Blood flow is a function of the frequency of oscillation. At 3.5 Hz, periodic acceleration using +/-0.6G and +/-1.2 cm oscillations induces forward blood flow of 2.1L/min and systemic perfusion pressure of 47 mmHg. A form of resonance occurs at the frequency for peak-flow, in which the period of oscillation matches the round-trip transit time for reflected pulse waves in the aorta. For +/-1.0 G acceleration at 3.5 Hz, systemic perfusion pressure is 80 mmHg and forward flow is 3.8L/min in the adult human model with longitudinal z-axis motion of only +/-2 cm. Similar results can be obtained using abdominal compression to excite resonant pressure-volume waves in the aorta. For 20 mmHg abdominal pressure pulses at 3.8 Hz, systemic perfusion pressure is 7 mmHg and forward flow is 2.8L/min. pGz-CPR and high-frequency abdominal CPR are the physically realistic means of generating artificial circulation during cardiac arrest. These techniques have fundamental mechanisms and practical features quite different from those of conventional CPR and the potential to generate superior systemic perfusion. PMID: 16563598 [PubMed - indexed for MEDLINE] Resuscitation. 2001 Oct;51(1):55-62. Links Novel CPR with periodic Gz acceleration. Adams JA, Mangino MJ, Bassuk J, Kurlansky P, Sackner MA. Department of Research, Division of Neonatology, Mount Sinai Medical Center, and Miami Heart Research Institute, 4300 Alton Road, 3 Blum, Miami Beach, FL 33140, USA. [EMAIL PROTECTED] The effects of periodic Gz acceleration (pGz) on cardiovascular function and hemodynamics were determined in a pig model of acute cardiopulmonary resuscitation (CPR). The application of pGz (horizontal head-to-foot oscillations) at 2 Hz increased cardiac output in fibrillated animals proportional to the amplitude of the applied acceleration force that plateaued at 0.7 G. Cardiac output in fibrillating animals was restored to 20% of the values obtained before fibrillation with pGz-CPR and arterial blood gas values were normal during this period. The central vascular pressure gradient driving blood flow was only about 6 mmHg, suggesting low vascular resistance during pGz-CPR. In another study, capillary blood flow was determined before and after pGz-CPR using colored microspheres. Capillary perfusion was detected in all tissue beds studied during pGz-CPR. Significant capillary blood flow was detected in the endocardium and brain stem during pGz-CPR that represented 39 and 197% of control values before fibrillation, respectively. Thus, the cardiac output during pGz-CPR was preferentially distributed to the myocardial and brain tissues. In a final group, animals were successfully resuscitated with return of spontaneous circulation (ROSC) after pGz-CPR for 15 min following cardiac fibrillation with a 3-min non-intervention period. Following ROSC, blood pressure was maintained at pre-arrest values for 2 h without any pharmacological or mechanical support. Arterial blood gases during the pGz-CPR and the ROSC periods were normal and not different from values obtained before fibrillation. None of the control animals (18 min of fibrillation without pGz-CPR) survived the experimental protocol and only two of these six animals briefly returned to spontaneous circulation (<20 min). In conclusion, experimental pGz-CPR produces cardiac output, capillary blood flow, and ventilation sufficient to maintain fibrillating animals for 18 min with ROSC for 2 h without support. PMID: 11719174 [PubMed - indexed for MEDLINE] Resuscitation. 2003 Feb;56(2):215-21. Links Survival and normal neurological outcome after CPR with periodic Gz acceleration and vasopressin. Adams JA, Bassuk J, Wu D, Kurlansky P. Division of Neonatology, Department of Research, Mount Sinai Medical Center, Miami Beach, FL 33140, USA. [EMAIL PROTECTED] BACKGROUND: We showed previously that whole body periodic acceleration along the spinal axis (pGz) is a novel method of cardiopulmonary resuscitation (CPR). The ultimate assessment of the value of any CPR technique is the neurological outcome after using such a technique. In this study, we determined the neurological outcome in pigs after prolonged pGz-CPR, with administration of vasopressin immediately prior to defibrillation. Neurological outcome after pGz-CPR was compared to a control group where no intervention occurred for the same time period (C-NoInterv). METHODS AND RESULTS: Ventricular Fibrillation (VFIB) was induced in 12 animals. After a 3 min non-interventional interval, the animals received either pGz-CPR (n=7), or C-NoInterv (n=5) for 15 min. After 18 min of VFIB, a single dose of vasopressin (0.8 U/kg) was administered along with sodium bicarbonate and bretylium, and defibrillation was attempted. All animals in the pGz-CPR group had return of spontaneous circulation (ROSC) and normal neurological assessment at 24 h. Neurologic outcome remained normal at 48 h. In contrast, none of the animals in the C-NoInterv had ROSC. CONCLUSION: Prolonged pGz-CPR, with administration of vasopressin immediately prior to defibrillation results in normal neurological outcomes at 24 h. PMID: 12589997 [PubMed - indexed for MEDLINE] Resuscitation. 2006 Sep;70(3):454-62. Epub 2006 Jul 10. Links Post-resuscitation reperfusion injury: comparison of periodic Gz acceleration versus Thumper CPR. Wu D, Bassuk J, Arias J, Peschiera I, Lamet A, Kurlansky P, Adams JA. Department of Research and Division of Neonatology, Mount Sinai Medical Center, 4300 Alton Road, Miami Beach, FL 33140, USA. [EMAIL PROTECTED] The effects of whole body, periodic acceleration (pGz) on cardiopulmonary resuscitation outcome, organ blood flow and tissue inflammatory injury were examined in an experimental pig model, and compared with Thumper (TH)-CPR. VF was induced in 16 pigs, and remained untreated for 3 min, followed by either pGz-CPR or TH-CPR for 15 min. Defibrillation attempts were made at 18 min of VF. Six of eight animals had ROSC in both groups. Post-arrest myocardial dysfunction was present in both groups and progressed over hours. pGz-CPR animals had less wall motion abnormality and higher left ventricular ejection fraction than TH-CPR. The post-resuscitation haemodynamic variables returned to baseline after 3h of ROSC in pGz-CPR group, and remained low in TH-CPR group. The brain blood flow during CPR was similar between TH-CPR and pGz-CPR, 17% and 20% of pre-fibrillation values, respectively. The cardiac blood flow during CPR was significantly lower in pGz-CPR than TH-CPR (TH: 10.2% and pGz: 1.9% of pre-fibrillation value), as well as in other organs. The brain and heart blood flow was significantly higher than pre-fibrillation values after 30 min of ROSC in both groups. The pGz group had significantly higher blood flow in brain, heart and kidney than TH-CPR after 30 min of ROSC. Blood flow in all organs decreased below pre-fibrillation values at 2h of ROSC. Tissue inflammatory injury progressed over hours in the post-resuscitation phase. pGz-CPR group had significantly lower myeloperoxidase (MPO) activity and plasma creatine phosphokinase (CPK) and cardiac troponin I, TNF-alpha, and IL-6 than TH-CPR. Results from the present study demonstrate again that pGz-CPR is an effective method of cardiopulmonary resuscitation, with less post-reperfusion injury compared to TH-CPR. PMID: 16828959 [PubMed - in process] Resuscitation. 2005 Jul;66(1):91-7. Links Echocardiographic comparison of cardiopulmonary resuscitation (CPR) using periodic acceleration (pGz) versus chest compression. Nava G, Adams JA, Bassuk J, Wu D, Kurlansky P, Lamas GA. Divisions of Cardiology, Neonatology, Department of Research, Mount Sinai Medical Center, Miami Heart Research Institute, 4300 Alton Road, Miami Beach, FL 33140, USA. OBJECTIVE: This investigation compared the effects of conventional cardiopulmonary resuscitation (CPR) using an automated Thumper chest compression device to periodic acceleration CPR (pGz-CPR) on early post-resuscitation ventricular function assessed by echocardiography, in an adult pig model of CPR. BACKGROUND: Whole body periodic acceleration along the spinal axis (pGz) is a new method of cardiopulmonary resuscitation (CPR). Biomechanical forces and biochemical release produced by pGz impart ventilation and increase blood flow. Our laboratory has reported normal neurological and cardiovascular function 48 h after return of spontaneous circulation in animals that have undergone 22 min of pGz-CPR. METHODS: Ventricular fibrillation (VF) was induced in 16 animals (25-35 kg). After 3 min of non-interventional period, the animals were randomized to receive either pGz-CPR or Thumper-CPR for 15 min. After 18 min of VF, a single dose of vasopressin and bicarbonate were administered and defibrillation attempted. An echocardiogram was performed at baseline and serially for 6h. Ejection fraction (EF), fractional shortening (FS) and wall motion were assessed by 2D and M-mode echocardiography. RESULTS: Return of spontaneous circulation to 360 min occurred in 5/8 (62%) of the animals receiving Thumper-CPR and in 7/8 (88%) receiving pGz-CPR. FS and EF were impaired after CPR, but pGz-CPR animals had less impairment than Thumper-CPR animals. Further, wall motion score index (WMSI) was more impaired after Thumper-CPR and remained as such even 6h post-CPR. CONCLUSION: pGz holds promise as a new method for CPR with better left ventricular (LV) function post-CPR than the more traditional chest compression method. PMID: 15993734 [PubMed - indexed for MEDLINE]
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