Manual External Chest Compressions Research Articles

Manual external chest compression reverses respiratory failure in children with severe air trapping.

We report manual external chest compression (MECC) as an effective treatment for acute respiratory failure due to severe air trapping. In this retrospective study, we describe our experience with MECC administered to five children suffering from severe air trapping as a consequence of severe asthma or bronchiolitis. These children were admitted to the Pediatric Intensive Care Unit (PICU) with clinical and blood gases parameters compatible with acute respiratory failure. Before intubation MECC was performed. The results of blood gasses before, during, and after MECC showed gradual changes in PCO2 over time indicating the improvement in tidal volume and ventilation. Respiratory failure resolved in all five children within 4 h with no complications. The need for intubation and mechanical ventilation was avoided, and all children were discharged from the PICU within 48 h.

ACLS and Chest Compressions in Patients with Durable LVADs

Introduction Durable left ventricular assist devices (LVADs) are increasingly used to improve longevity in patients with advanced heart failure; however, optimal management of end-of-life issues including cardiopulmonary arrest remains uncertain for this relatively new population. We aim to assess the safety and efficacy of Advanced Cardiovascular Life Support (ALCS) including chest compressions in patients with LVADs. Methods We performed a retrospective chart review of all LVAD patients that received ACLS and chest compressions for in-hospital cardiopulmonary arrest at a single academic medical center between 2011 and 2017. We evaluated post-arrest survival, LVAD parameters/function, imaging studies, and autopsy results to assess for (1) structural issues such as LVAD dislodgment, aortic dissection/rupture, or pericardial effusion, and (2) LVAD mechanical issues such as hardware or software failure. Results Durable LVADs were implanted in 191 patients during the study period, of which 18 patients (9%) suffered in-hospital cardiopulmonary arrest necessitating ACLS (median of 22.5 days, range from 1 to 1323 days from implant). Of the patients requiring ACLS 11 (61%) survived the arrest with 7 (39%) surviving to hospital discharge. Ten patients (56%) received manual external chest compressions, and 7 (39%) received defibrillator shocks. Of the patients who received chest compressions and/or defibrillator shocks, no significant changes to LVAD parameters/function was noted after the arrest. Five autopsies were completed, all of which reported the LVAD in its proper position without evidence structural or mechanical LVAD complications. Two of the surviving patients were taken emergently to the operating room for treatment of cardiac tamponade; during the procedure the LVAD anastomoses were inspected, and no bleeding was noted in either case. Two echocardiograms were performed following chest compressions without evidence of LVAD dysfunction. There were no iatrogenic sequelae identified in any of the patients following ACLS. Conclusion While cardiopulmonary arrest in patients with LVADs is associated with high mortality, ACLS with chest compressions appears to be safe. Larger studies are warranted to identify patterns of post ALCS complications and define potential population-specific management.

Three Methods of Manual External Chest Compressions During Microgravity Simulation

Cardiopulmonary resuscitation (CPR) in microgravity is challenging. There are three single-person CPR techniques that can be performed in microgravity: the Evetts-Russomano (ER), Handstand (HS), and Reverse Bear Hug (RBH). All three methods have been evaluated in parabolic flights, but only the ER method has been shown to be effective in prolonged microgravity simulation. All three methods of CPR have yet to be evaluated using the current 2010 guidelines. There were 23 male subjects who were recruited to perform simulated terrestrial CPR (+1 G(z)) and the three microgravity CPR methods for four sets of external chest compressions (ECC). To simulate microgravity, the subjects used a body suspension device (BSD) and trolley system. True depth (D(T)), ECC rate, and oxygen consumption (Vo2) were measured. The mean (+/- SD) D(T) for the ER (37.4 +/- 1.5 mm) and RBH methods (23.9 +/- 1.4 mm) were significantly lower than +1 G(z) CPR. However, both methods attained an ECC rate that met the guidelines (105.6 +/- 0.8; 101.3 +/- 1.5 compressions/min). The HS method achieved a superior D(T) (49.3 +/- 1.2 mm), but a poor ECC rate (91.9 +/- 2.2 compressions/min). Vo2 for ER and HS was higher than +1 Gz; however, the RBH was not. All three methods have merit in performing ECC in simulated microgravity; the ER and RBH have adequate ECC rates, and the HS method has adequate D(T). However, all methods failed to meet all criteria for the 2010 guidelines. Further research to evaluate the most effective method of CPR in microgravity is needed.

The effect of levosimendan combined with 20% lipid emulsion treatment on survival from bupivacaine induced toxicity in experiment.

Recent reports demonstrated that levosimendan improved post-resuscitation myocardial function in rat and pig models. Rabbits were randomized into 4 groups as 12 rabbits in each group. Bupivacaine 10 mg/kg was injected as an intravenous bolus to all groups. Basic life support was performed by mechanical ventilation and manual external chest compressions. After 1 min, animals in the group 1 received 1.5 ml/ kg saline 0.9% solution, and animals in the groups 2 and 4 received 5 ml/kg 20% lipid emulsion for 1 min through the ear vein followed by continuous infusion at 0.25 ml/kg/min. Three additional boluses of 1.5 ml/ kg lipid emulsion were repeated at 5-min intervals. The group 3 received fluid resuscitation plus levosimendan (3 µg/kg/min) 1 min after asystole and the group 4 received both levosimendan and lipid emulsion treatment. Return of spontaneous circulation and hemodynamic metrics were obtained in 20 minutes. The number of rabbits that survived after cardiac resuscitation was lower in the Groups 1 (0%) and 3 (33.3%) than in the Group 4 (91.7%) with a statistically significant difference (p < 0.001). The number of rabbits that survived resuscitation was higher in the Group 4 than in the Group 2 (66.7%), though not with a statistically significant difference (p = 0.317). The median duration of cardiac arrest in the Group 4 was significantly shorter than that in the other three groups (p < 0.001). In this rabbit model of bupivacaine-induced cardiac arrest, resuscitation with combined iv lipid emulsion and levosimendan was more efficacious than lipid alone (Tab. 3, Ref. 24).

Web-based general public opinion study of automated versus manual external chest compression

BackgroundOnly a few cardiac-arrest victims receive external chest compression (ECC) by a bystander.ObjectiveTo test the hypothesis that the general public might start ECC more often if they used an automated...

The effect of the external chest compression appliance (AutoPulse) on cardiac arrest in the emergency department and influence on blood gas and N-terminal B-type natriuretic peptide

To investigate the value of AutoPulse in the patients with cardiac arrest (CA) in emergency department. Patients with CA seen in the Emergency Department of Chaoyang Hospital, Affiliated to Capital Medical University from September 2008 to August 2009 were divided into standard manual external chest compression group (n=42) and mechanical chest compression group with AutoPulse (n=43), based on the method of the external chest compression . Tracheal intubation was performed and mechanical ventilation instituted in all the patients. Other rescue measures, such as intravenous infusion of fluids, electrocardiogram, electric shock for defibrillation were performed following the cardiopulmonary guideline of 2005. The patients with restoration of spontaneous circulation in 20 minutes were excluded. Among patients with resuscitation over 20 minutes, there were 29 cases in AutoPulse group and 28 cases in standard manual external chest compression group. The blood gas and N-terminal B-type natriuretic peptide (NT-proBNP) from the blood samples obtained from the femoral artery 20 minutes after resuscitation were determined, and the survival rate at 2 hours and 24 hours in both groups was recorded. Twenty minutes after cardiopulmonary resuscitation, the pH value and the arterial partial pressure of oxygen (PaO(2)) of the AutoPulse group (n=29) were significantly higher than those of the standard manual external chest compression group [n=28, pH value: 7.142±0.134 vs. 7.010±0.136, PaO(2) ( mm Hg, 1 mm Hg= 0.133 kPa): 71.92±9.59 vs. 65.61±7.66, both P<0.01], the arterial partial pressure of carbon dioxide (PaCO(2)) and NT-proBNP were significantly lower than those of the standard manual external chest compression group [PaCO(2) (mm Hg): 39.43±14.09 vs. 51.07±16.31, NT-proBNP (ng/L) : 548.18±256.93 vs. 699.40±303.35, P<0.01 and P<0.05]. The 2-hour survival rate in AutoPulse group was higher than that in the standard manual external chest compression group, the disparity of the two groups was statistically significant [74.4% (32/43) vs. 52.4% (22/42), P<0.05]. Though the 24-hour survival rate of AutoPulse group was higher than that of the standard manual external chest compression group, the difference was not statistically significant [9.3% (4/43) vs. 4.8% (2/42), P>0.05]. The device of AutoPulse can improve the tissue perfusion in patients with CA. Though this device may give rise some benefit in resuscitation for a short time, there is no decisive improvement in term of outcome of the patient.

Hemodynamic, respiratory, and perfusion parameters during asphyxia, resuscitation, and post-resuscitation in a pediatric model of cardiac arrest

To analyze the evolution of hemodynamic, respiratory, and tissue perfusion parameters in an infant animal model of asphyxial cardiac arrest (CA). This was a secondary analysis of a prospective observational study conducted at a laboratory research department of a university hospital. Seventy-one, 2-month-old piglets were studied. CA was induced by removal of mechanical ventilation. Cardiopulmonary resuscitation (CPR) was performed by means of manual external chest compressions, mechanical ventilation, epinephrine and/or terlipressin intravenous administration. The evolution of hemodynamic (heart rate, blood pressure, cardiac index), respiratory (end-tidal CO(2), blood gas analysis), and tissue perfusion (intramucosal gastric pH, central, cerebral, and renal hemoglobin saturation) parameters was analyzed during three periods: asphyxia, CPR, and after return of spontaneous circulation (ROSC). During asphyxia, a severe arterial and tissue hypoxia with hypercapnia and lactic acidosis quickly developed. Bradycardia, hypotension, and increasing of systemic vascular resistances and pulmonary arterial pressure were also observed. During CPR, arterial, cerebral, and tissue oxygenation were low in spite of ventilation with oxygen 100%. After ROSC a rapid restoration of hemodynamic and respiratory parameters was observed. However, 30min after ROSC, lactic acidosis and low intramucosal gastric pH persisted. Asphyxia leads to sudden hypoxia and hypercapnia with tissue hypoxia and progressive bradycardia. Standard CPR is not able to maintain an adequate tissue oxygenation during CPR in this animal model. When ROSC is achieved, a rapid restoration of the normal values of general hemodynamic and respiratory parameters is observed, although lactic acidosis and splanchnic hypoperfusion persist in time.

Terlipressin versus adrenaline in an infant animal model of asphyxial cardiac arrest

The objective of this study was to compare the efficacy of terlipressin versus adrenaline in an experimental infant animal model of asphyxial cardiac arrest (ACA). Prospective randomised animal study. Laboratory research department of a university hospital. Seventy-one, 2-month-old, mechanically ventilated piglets were investigated. ACA was induced by removal of mechanical ventilation. Resuscitation was performed by means of manual external chest compressions and mechanical ventilation (CC + V). After 3 min of CC + V, return of spontaneous circulation (ROSC) was observed in 11 animals. The 60 piglets without ROSC were then randomised to the four study groups: adrenaline standard dose (Asd): 0.01 mg/kg/3 min; adrenaline high dose (Ahd): first dose (0.01 mg/kg) and subsequent doses (0.1 mg/kg/3 min); terlipressin (T): 20 microg/kg/6 min; and adrenaline standard dose plus terlipressin (Asd + T). The relationship between haemodynamic (heart rate, blood pressure, ECG rhythm, cardiac index), respiratory (end-tidal CO(2), blood gas analysis) and tissue perfusion (gastric intramucosal pH, central, cerebral and renal saturation) parameters and ROSC was analysed. ROSC was achieved in three piglets treated with Asd (20%), four treated with Ahd (26.7%), one treated with T (6.7%) and seven treated with Asd + T (46.7%) (P = 0.099). ROSC was achieved in 43.1% of animals with pulseless electrical activity, 30.4% with asystole and none with ventricular fibrillation (P = 0.0001). In this infant animal model of cardiac arrest, there was a non-significant trend towards better outcome when terlipressin was combined with adrenaline compared with the use of adrenaline or terlipressin alone.

Increased cortical cerebral blood flow with LUCAS; a new device for mechanical chest compressions compared to standard external compressions during experimental cardiopulmonary resuscitation

Objective: LUCAS is a new device for mechanical compression and decompression of the chest during cardiopulmonary resuscitation (CPR). The aim of this study was to compare the efficacy of this new device with standard manual external chest compressions using cerebral cortical blood flow, cerebral oxygen extraction, and end-tidal CO 2 for indirect measurement of cardiac output. Drug therapy, with adrenaline (epinephrine) was eliminated in order to evaluate the effects of chest compressions alone. Methods: Ventricular fibrillation (VF) was induced in 14 anaesthetized pigs. After 8 min non-intervention interval, the animals were randomized into two groups. One group received external chest compressions using a new mechanical device, LUCAS. The other group received standard manual external chest compressions. The compression rate was 100 min −1 and mechanical ventilation was resumed with 100% oxygen during CPR in both groups. No adrenaline was given. After 15 min of CPR, external defibrillatory shocks were applied to achieve restoration of spontaneous circulation (ROSC). Cortical cerebral blood flow was measured continuously using Laser-Doppler flowmetry. End-tidal CO 2 was measured using mainstream capnography. Results: During CPR, the cortical cerebral blood flow was significantly higher in the group treated with LUCAS ( p = 0.041). There was no difference in oxygen extraction between the groups. End-tidal CO 2, an indirect measurement of the achieved cardiac output during CPR, was significantly higher in the group treated with the LUCAS device ( p = 0.009). Restoration of spontaneous circulation was achieved in two animals, one from each group. Conclusions: Chest compressions with the LUCAS device during experimental cardiopulmonary resuscitation resulted in higher cerebral blood flow and cardiac output than standard manual external chest compressions. These results strongly support prospective randomised studies in patients to evaluate this new device.

CPREzy™: an evaluation during simulated cardiac arrest on a hospital bed

CPREzy is a new adjunct designed to improve the application of manual external chest compressions (ECC) during cardiopulmonary resuscitation (CPR). The aim of this study was to determine the effect of using the CPREzy device compared to standard CPR during the simulated resuscitation of a patient on a hospital bed. Twenty medical student volunteers were randomised using a cross over trial design to perform 3 min of continuous ECC using CPREzy and standard CPR. There was a significant improvement in ECC depth with CPREzy compared to standard CPR 42.9 (4.4) mm versus 34.2 (7.6): mm, P = 0.001; 95% CI d.f. 4.4-12.9 mm. This translated to a reduction in the percentage of shallow compressions (<38 mm) with CPREzy 16 (23)% compared to standard CPR 59 (44)%, P = 0.003. There was a small increase in the percentage of compression regarded excessive (>51 mm): CPREzy 6.5 (19)% versus standard CPR 0 (0.1)%. P = 0.012). There was no difference in compression rate or duty cycle between techniques. Equal numbers of participants (40% in each group) performed one of more incorrectly placed chest compression. However the total number of incorrect compressions was higher for the CPREzy group (26% versus 3.9% standard CPR, P < 0.001). This was due to a higher number of low compressions (26% of total compressions for CPREzy versus 1% for standard CPR, P < 0.001). In conclusion, CPREzy was associated with significant improvements in ECC performance. Further animal and clinical studies are required to validate this finding in vivo and to see if it translates to an improvement in outcome in human victims of cardiac arrest.

A LTERNATIVE C ARDIOPULMONARY R ESUSCITATION D EVICES

Cardiopulmonary resuscitation (CPR) involving manual external chest compression combined with artificial respiration was first described in 1960 by Kouwenhoven et al. (Kouwenhoven W, Jude JR, Knickerbocker GG. Closed-chest cardiac massage. JAMA. 1960;173:1064-7). In the four decades since then, there have been no widely accepted alternatives for this technique. Even with the subsequent worldwide adoption of CPR and other advanced cardiac life support measures, long-term survival after prehospital cardiac arrest is still typically only 5% to 10%. The performance of CPR must therefore be improved to increase the rate of long-term survival. Currently under development are new, alternative techniques such as interposed abdominal compression (IAC), active compression- decompression (ACD), pneumatic and nonpneumatic circumferential chest compression, and minimally invasive cardiac massage. Many of these newer techniques, compared with standard manual CPR, appear to provide superior vital organ blood flow and increased blood pressure. To date, only IAC (in-hospital only) and ACD have been shown to improve long-term survival in clinical studies. Circumferential chest compression and minimally invasive cardiac massage, on the other hand, have not yet been adequately tested in large clinical trials. Despite the difficulty and expense in studying these CPR techniques, additional research is necessary to evaluate their effectiveness in improving survival after sudden cardiac arrest.

Automatic and manual mechanical external chest compression devices for cardiopulmonary resuscitation

Modern cardiopulmonary resuscitation (CPR) is only 35 years old [1], but Boehm did record successful external CPR in animals in 1878 [2], and Maass described the method in patients in 1892 [3]. Kouwenhoven rediscovered artificial circulation by manual external chest compressions (ECC) in 1960 with laboratory documentation and the first clinical proof of efficacy [1]. Later this group reported that external cardiac massage, combined with artificial respiration could restore cardiac and neurological function before defibrillation in more than 60% of their series of cardiac arrests [4]. Peter Safar organised the knowledge available in the early 1960s into ‘Airway, Breathing and Circulation’ [5]. ECC became step C of the US national [6] and World Federated Society for Anesthesiologists (WFSA) international guidelines [5]. These have been revised several times [7–10], and since 1992 the European Resuscitation Council have published European versions of the guidelines [11,12]. Early defibrillation is the most important single factor to influence survival in out-of-hospital resuscitation, but the majority of patients (\60%) will receive basic life support consisting of chest compression and ventilation before defibrillation is available [12–15]. One study has even suggested that patients suffering cardiac arrest of more than 4 min should be given routinely chest compressions for a short period before defibrillation [16]. Scientists have tried to improve CPR techniques by focusing on manual or automatic driven devices to provide more consistent chest compressions and ventilations. At present there are manual and mechanical automatic devices that provide Vest CPR [17], active compression–decompression (ACD) CPR [18,19], phased thoracic–abdominal compression and decompression (PTACD) CPR [20], standard CPR [21–36], and automatic Belt CPR [unpublished data]. There are four main needs for mechanical ECC: 1. For the scientific study of CPR to provide consistent levels of support according to a protocol. 2. To optimise CPR performance based on the present standards for ECC. 3. To perform CPR using new protocols, optimised for machine resuscitation. 4. To provide basic life support (BLS), and allow the rescuer to concentrate on advanced life support (ALS) and start post resuscitative brain-oriented protective therapy. * +47-22868495. E-mail address: lars.wik@chello.no (L. Wik).

Epinephrine and sodium bicarbonate during CPR following asphyxial cardiac arrest in rats

Although high-dose epinephrine during CPR improves coronary perfusion pressure (CoPP) and rate of return of spontaneous circulation (ROSC) in some models, its impact on long term outcome (≥ 72 h) has not been evaluated. Previous studies of sodium bicarbonate (NaHCO 3) therapy during CPR indicate that beneficial effects may be dependent on epinephrine (EPI) dose. We hypothesized that EPI and NaHCO 3 given during CPR have a significant impact on long term outcome. One hundred male Sprague-Dawley rats were prospectively studied in a block randomized placebo controlled trial. Rats were anesthetized, paralyzed, mechanically ventilated, instrumented, and each underwent 10 min of asphyxia, resulting in 6.8 ± 0.4 min of circulatory arrest. Resuscitation was performed by mechanical ventilation and manual external chest compressions. EPI 0.0 (placebo), 0.01, 0.1, or 1.0 mg/kg IV was given at the onset of CPR, followed by NaHCO 3 0.0 (placebo) or 1.0 mEq/kg IV. Successfully resuscitated rats were monitored and ventilated for l h without hemodynamic support. Neurologic deficit scores (NDS), cerebral histopathologic damage scores (CHDS) and myocardial histopathologic damage scores (MHDS) were determined in rats that survived 72 h, EPI improved CoPP and ROSC in a dose-dependent manner up to 0.1 mg/kg. Rats receiving EPI 0.1 and 1.0 mg/kg during CPR exhibited prolonged post-ROSC hypertension and metabolic acidemia, increased A-a O 2 gradient, and an increased incidence of post-ROSC ventricular tachycardia or fibrillation. Overall survival was lower with EPI 0.1 and 1.0 mg/kg compared to 0.01 mg/kg. Although NDS was significantly less with EPI 0.1 mg/kg compared to placebo, there was no difference in CHDS between groups. In contrast, MDS was significantly higher with EPI 0.1 mg/kg compared to placebo or EPI 0.01 mg/kg. There was an overall trend toward improved survival at 72 h in rats that received NaHCO 3 which was most evident in the EPI 0.1 mg/kg group. We conclude that (1) EPI during CPR has a biphasic dose/response curve in terms of survival, when post-resuscitation effects are left untreated and (2) NaHCO 3 doses greater than 1.0 mEq/kg may be necessary to treat the side-effects of high-dose EPI. Further work is needed to determine if treating the immediate post-resuscitation effects of high-dose EPI can prevent detrimental effects on long-term outcome.

Selective aortic perfusion and oxygenation: An effective adjunct to external chest compression-based cardiopulmonary resuscitation

Objectives. The purpose of this study was to compare the perfusion pressure and rate of return of spontaneous circulation produced by advanced cardiac life support with that resulting from advanced cardiac life support with simultaneous aortic occlusion and proximal infusion with oxygenated fluid.Background. Cardiopulmonary-resuscitation based solely on external chest compression is unable to achieve return of spontaneous circulation in most patients with cardiac arrest. Adjunctive therapies that enhance myocardial oxygen supply may improve outcomes.Methods. We conducted a prospective, randomized study in mongrel dogs using a fibrillatory model of cardiac arrest with a 20-min arrest time. Dogs were randomized to two groups. Aortic arch and right micromanometers were placed to measure intravascular pressure. Manual external chest compression was used and standardised to an esophageal pulse pressure of 50 mm Hg. Two minutes after initiation of advanced cardiac life support, selective aortic perfusion and oxygenation were initiated in dogs assigned to one group by inflation of an occluding balloon in the descending aorta and infusion of 450 ml of ultrapurified polymerized bovine hemoglobin through a large bore central infusion port.Results. Maximal aortic pressure during standard advanced cardiac life support was 42 ± 23 (mean ± SD) versus 69 ± 28 mm Hg during advanced cardiac life support with selective aortic perfusion and oxygenation. Maximal coronary perfusion pressure during standard therapy was 33 ± 21 versus 62 ± 26 mm Hg during combined therapy. Only 2 of 10 dogs receiving standard therapy had return of spontaneous circulation versus 6 of 7 receiving combined therapy. Balloon occlusion alone did not increase perfusion pressure significantly.Conclusions. The use of selective aortic perfusion and oxygenation increases aortic and coronary perfusion pressures during cardiopulmonary resuscitation, resulting in a large increase in the rate of return of spontaneous circulation. This technique may be an effective adjunct to advanced cardiac life support based on any method of external chest compression and may improve the poor prognosis of patients with cardiac arrest.

The effect of global ischemia and reperfusion on the plasma levels of vasoactive peptides. The neuroendocrine response to cardiac arrest and resuscitation.

Return of spontaneous circulation with CPR is a function of coronary perfusion pressure, which is determined by vasomotor tone and the force of compression. Vasomotor tone is affected by the relative stimulation of arterial vasoconstricting and vasorelaxing receptors by vasoactive substances. We measured the plasma levels of the endogenous vasoactive peptides arginine vasopressin (AVP) angiotensin II (ANG-II) and atrial natriuretic peptide (ANP) during cardiac arrest and resuscitation. A fibrillatory canine model of canine arrest was used. 'Down time' was greater than 10 min, during which no therapy, including BLS, was given. Standard ACLS was initiated at the end of the down time with manual external chest compression standardized to an esophageal pulse pressure of 50 mmHg. Blood samples were collected through an aortic catheter during spontaneous circulation and 3 min after initiation of ACLS. Peptide levels were measured using standard RIA techniques. Results are reported as the mean +/- S.D. in pg/ml. AVP levels increased from a baseline of 1.7 +/- 1.0 pg/ml during spontaneous circulation to 29.9 +/- 33.3 during cardiac arrest and CPR (P = 0.01). There was a moderate positive correlation between aortic pressure and circulating AVP levels after the first dose of epinephrine (R = 0.5). There was a trend towards higher AVP levels in animals with return of spontaneous circulation (P = 0.12). ANG-II levels increased from a baseline of 14.7 +/- 12.9 pg/ml during spontaneous circulation to 151 +/- 105 during cardiac arrest and CPR (P < 0.05). ANP levels increased from a baseline of 55 +/- 46 pg/ml during spontaneous circulation to 293 +/- 73 during cardiac arrest and CPR (P < 0.01). There were significant increases in the levels of these endogenous vasoactive peptides. This reflects the neuroendocrine response to global ischemia and CPR reperfusion. Plasma levels of these peptides may effect the vital organ perfusion pressures, response to exogenous vasopressors, and outcome of resuscitative efforts. Future therapies may be directed at enhancing or blocking the effect of these peptides so as to optimize perfusion pressure which is one of the principle determinants of outcome during CPR.

Determinants of blood flow to vital organs during cardiopulmonary resuscitation in dogs.

Whether blood flow during cardiopulmonary resuscitation (CPR) results from intrathoracic pressure fluctuations or direct cardiac compression remains controversial. From modeling considerations, blood flow due to intrathoracic pressure fluctuations should be insensitive to compression rate over a wide range, but dependent on the applied force and compression duration. If direct compression of the heart plays a major role, however, flow should be dependent on compression rate and force, but above a threshold, insensitive to compression duration. These differences in hemodynamics produced by changes in rate and duration form a basis for determining whether blood flow during CPR results from intrathoracic pressure fluctuations or from direct cardiac compression. Manual CPR was studied in eight anesthetized, 21 to 32 kg dogs after induction of ventricular fibrillation. There was no surgical manipulation of the chest. Myocardial and cerebral blood flows were determined with radioactive microspheres. At nearly constant peak sternal force (378 to 426 newtons), flow was significantly increased when the duration of compression was increased from 14 +/- 1% to 46 +/- 3% of the cycle at a rate of 60/min. Flow was unchanged, however, after an increase in rate from 60 to 150/min at constant compression duration. The hemodynamics of manual CPR were next compared with those produced by vest inflation with simultaneous ventilation (vest CPR) in eight other dogs. Vest CPR changed intrathoracic pressure without direct cardiac compression, since sternal displacement was less than 0.8 cm. At a rate of 150/min, with similar duration and right atrial peak pressure, manual and vest CPR produced similar flow and perfusion pressures. Finally, the hemodynamics of manual CPR were compared with the hemodynamics of direct cardiac compression after thoracotomy. Cardiac deformation was measured and held nearly constant during changes in rate and duration. As opposed to changes accompanying manual CPR, there was no change in perfusion pressures when duration was increased from 15% to 45% of the cycle at a constant rate of 60/min. There was, however, a significant increase in perfusion pressures when rate was increased from 60 to 150/min at a constant duration of 45%. Thus, vital organ perfusion pressures and flow during manual external chest compression are dependent on the duration of compression, but not on rates of 60 or 150/min. These data are similar to those observed for vest CPR, where intrathoracic pressure is manipulated without sternal displacement, but opposite of those observed for direct cardiac compression.(ABSTRACT TRUNCATED AT 400 WORDS)