Ingrid M. Lindner

Randomised comparison of epinephrine and vasopressin in patients with out-of-hospital ventricular fibrillation

BACKGROUND Studies in animals have suggested that intravenous vasopressin is associated with better vital-organ perfusion and resuscitation rates than is epinephrine in the treatment of cardiac arrest. We did a randomised comparison of vasopressin with epinephrine in patients with ventricular fibrillation in out-of-hospital cardiac arrest. METHODS 40 patients in ventricular fibrillation resistant to electrical defibrillation were prospectively and randomly assigned epinephrine (1 mg intravenously; n = 20) or vasopressin (40 U intravenously; n = 20) as primary drug therapy for cardiac arrest. The endpoints of this double blind study were successful resuscitation (hospital admission), survival for 24 h, survival to hospital discharge and neurological outcome (Glasgow coma scale). Analyses were by intention to treat. FINDINGS Seven (35%) patients in the epinephrine group and 14 (70%) in the vasopressin group survived to hospital admission (p = 0.06). At 24 h, four (20%) epinephrine-treated patients and 12 (60%) vasopressin-treated patients were alive (p = 0.02). Three (15%) patients in the epinephrine group and eight (40%) in the vasopressin group survived to hospital discharge (p = 0.16). Neurological outcomes were similar (mean Glasgow coma score at hospital discharge 10.7 [SE 3.8] vs 11.7 [1.6], p = 0.78). INTERPRETATION In this preliminary study, a significantly larger proportion of patients created with vasopressin than of those treated with epinephrine were resuscitated successfully from out-of-hospital ventricular fibrillation and survived for 24 h. Based upon these findings, larger multicentre studies of vasopressin in the treatment of cardiac arrest are needed.

Vasopressin administration in refractory cardiac arrest

In studies done in pigs, the administration of exogenous vasopressin during closed- and open-chest cardiopulmonary resuscitation has been shown to be more effective than optimal doses of epinephrine in improving vital organ blood flow and increasing perfusion pressure [1, 2]. Interest in the potential value of vasopressin administration during cardiopulmonary resuscitation also stems from human studies showing high levels of circulating vasopressin in patients in cardiac arrest [3, 4]. Higher levels of endogenous vasopressin are associated with greater chances for survival, and higher endogenous levels of epinephrine and norepinephrine are associated with decreased chances for survival [4]. To date, no case reports or controlled studies have addressed the potential value of exogenous vasopressin for the treatment of patients having cardiac arrest. In light of the data from the animal studies, eight patients having refractory in-hospital cardiac arrest were treated with vasopressin after standard therapies, including intravenous administration of epinephrine, had failed. Methods In a final effort to resuscitate patients in whom standard American Heart Association Advanced Cardiac Life Support therapies after in-hospital cardiac arrest had failed, arginine vasopressin was administered centrally as an initial 40-U bolus. Each patient had received standard manual cardiopulmonary resuscitation with at least 1 mg of epinephrine and an attempt at direct-current shock before receiving vasopressin through either a femoral or jugular vein. Table 1 lists patient demographic characteristics, and Table 2 provides some details of therapy and outcome after cardiac arrest. One of eight patients (patient 2) had an unwitnessed arrest. Cardiopulmonary resuscitation was initiated less than 1 minute after arrest in the remaining patients; cardiopulmonary resuscitation and advanced cardiac life support were done on all patients for at least 12 minutes (mean SD, 21.6 11.8 minutes) before vasopressin was administered. Three patients were discharged from the hospital with good neurologic recovery. Table 1. Demographic Characteristics of Patients Having In-Hospital Cardiac Arrest Refractory to Epinephrine*. Table 2. Time Intervals and Outcome in Patients Having In-Hospital Cardiac Arrest Refractory to Epinephrine*. Case Highlights Patient 4 Four days after having a hemicolectomy, a 78-year-old woman developed pulmonary emboli and ventricular fibrillation. Defibrillation (200 J) led to asystole. The patient received cardiopulmonary resuscitation and epinephrine (1-mg, 3-mg, and 5-mg doses administered 3 minutes apart). After the 5-mg bolus, ventricular fibrillation evolved but was resistant to repeated direct-current shocks and to lidocaine (100 mg). Central administration of vasopressin (40 U) followed by direct-current shock (360 J) resulted in a supraventricular rhythm with a palpable carotid pulse. A systolic blood pressure of approximately 100 mm Hg was maintained with a norepinephrine infusion of 0.15 g/kg of body weight per minute. After uncomplicated embolectomy, the patient was transferred to the intensive care unit for 3 days and was discharged without neurologic deficit 4 weeks later. Patient 5 A 71-year-old woman developed ventricular fibrillation while her chest was being scrubbed before implantation of a permanent pacemaker. Closed-chest cardiac massage was initiated within seconds. After three successive direct-current shocks (200 J, 300 J, and 300 J) followed by epinephrine (1 mg) and another direct-current shock (300 J), the patient remained in ventricular fibrillation. Examination of arterial blood gases showed a pH of 7.33 and a Po 2 of 60 mm Hg before endotracheal intubation. Additional epinephrine (1 mg) and defibrillation efforts were unsuccessful. Vasopressin (40 U) was administered 50 minutes after the arrest, and spontaneous circulation returned immediately after a 300-J direct-current shock. Immediately before vasopressin administration, the patients arterial blood had a pH of 7.18 and a Po 2 of 543 mm Hg. The patient was treated with dopamine (10 g/kg per minute) intravenously. Forty-five minutes later, she again developed hypotension followed by ventricular fibrillation. Cardiopulmonary resuscitation was reinitiated, but direct-current shock (300 J), epinephrine (1 mg), and another direct-current shock (300 J) failed to revive her. Vasopressin (20 U) followed 30 seconds later by direct-current shock (300 J) was unsuccessful; more vasopressin (20 U) was administered 2 minutes after the first 20-U dose. Thirty seconds later, a direct-current shock (300 J) led to an immediate return of spontaneous circulation. The patients pulmonary capillary wedge pressure at this time was 25 mm Hg, and her pulmonary systolic pressure was 35 mm Hg. Twenty minutes after her second and final resuscitation effort, she became hypotensive and bradycardic and died secondary to pulseless electrical activity. Patient 6 Immediately after induction with a standard cardiac general anesthetic for placement of an implantable cardioverter-defibrillator, a 45-year-old man developed pulseless electrical activity. Standard closed-chest manual cardiopulmonary resuscitation was started immediately. The patient received fluids (500 mL of normal saline), atropine (1 mg intravenously), and epinephrine (1 mg intravenously). After 10 minutes and another 1-mg epinephrine dose, he developed ventricular fibrillation. Several efforts to defibrillate failed. Twenty minutes after cardiac arrest, the patient received vasopressin (40 U); after a single 360-J transthoracic direct-current shock, spontaneous circulation promptly returned. The patient remained hemodynamically stable for 30 minutes. Despite intravenous fluids, dopamine (10 g/kg per minute), and placement of an intra-aortic balloon pump, he again developed hypotension, followed by ventricular fibrillation. After an effort to resuscitate the patient with standard cardiopulmonary resuscitation, epinephrine (1 mg), and direct-current shock was unsuccessful, the patient was given vasopressin (40 U) and was successfully resuscitated with direct-current shock. An angiogram showed a large thrombus at the site of an angioplasty done 2 weeks earlier; the vessel was again dilated. Within 30 minutes, the patient developed polymorphous ventricular tachycardia and had another cardiac arrest. Standard manual cardiopulmonary resuscitation, intravenous vasopressin (40 U), and direct-current shock were not effective. The patient received active compression-decompression cardiopulmonary resuscitation and vasopressin (40 U). Systolic arterial pressure increased to more than 100 mm Hg; when active compression-decompression cardiopulmonary resuscitation was stopped, the patient spontaneously convertedwithout direct-current shockto sinus tachycardia. One hour later, ventricular fibrillation again developed. Resuscitation efforts were terminated. Patient 8 A 31-year-old man had several internal injuries after a car accident. He developed ventricular fibrillation on the way to the operating room for emergent repair of a ruptured aorta. Fibrillation persisted despite many direct-current shocks and the administration of epinephrine (2 1 mg repeated after 3 minutes). After 4 minutes of closed-chest cardiopulmonary resuscitation, examination of the arterial blood showed a pH of 7.16, a Pco 2 of 54 mm Hg, a Po 2 of 49 mm Hg (fraction of inspired oxygen, 1.0), a potassium level of 2.8 mmol/L, and a hemoglobin level of 9.1 g/L. Despite treatment with epinephrine, diastolic arterial pressures remained less than 15 mm Hg. Administration of vasopressin (40 U) increased the diastolic arterial pressure to 30 mm Hg, and a subsequent direct-current shock (360 J) restored a stable heart and blood pressure. After the operation, the patient was transferred to the intensive care unit. Discussion These cases show that in patients in cardiac arrest who are receiving closed-chest cardiopulmonary resuscitation and have not responded to the standard doses of epinephrine recommended by the American Heart Association, spontaneous circulation can be restored by intravenous administration (through the femoral or jugular vein) of 40 U of vasopressin. These results are consistent with recent data from animals showing that vasopressin has greater efficacy than epinephrine during cardiopulmonary resuscitation [1, 2]. Although the prognosis was poor in all cases and all conventional measures had failed, spontaneous circulation was restored in all eight patients after vasopressin administration. Three patients survived to hospital discharge with minimal or no neurologic deficit. In addition, when active compression-decompression cardiopulmonary resuscitation was combined with the use of vasopressin, one patient had spontaneous conversion to sinus rhythm without the use of direct-current shock. Although the optimal dose of vasopressin in humans is not known, 40 U was effective in all of our patients. In one patient, a dose of 20 U was not effective. In the eight patients studied, an initial dose of 1 mg of epinephrine was administered. In four of these eight patients, an escalating dose of epinephrine (from 1 mg to 3 mg to 5 mg) was used but was similarly ineffective. In humans having cardiac arrest, epinephrine therapy is used on the basis of case reports and animal studies [5, 6]. Recent clinical trials comparing low-dose with high-dose epinephrine show that the latter has no significant advantage [7, 8]. A more recent placebo-controlled trial showed that neither high- nor low-dose epinephrine had benefit compared with placebo [9]. In our patients, vasopressin may have been more effective because of several factors. Vasopressin exerts a greater vasoconstrictive effect under conditions of hypoxia and acidosis than does epinephrine, and the effects of vasopressin last longer [1, 2]. Vasopressin causes a greater increase in arterial tone than does epine

Effects of active compression-decompression resuscitation on myocardial and cerebral blood flow in pigs.

BACKGROUND This study was designed to assess the effects of a modified cardiopulmonary resuscitation (CPR) technique that consists of both active compression and active decompression of the chest (ACD CPR) versus standard CPR (STD CPR) on myocardial and cerebral blood flow during ventricular fibrillation both before and after epinephrine administration. METHODS AND RESULTS During a 30-second period of ventricular fibrillation cardiac arrest, 14 pigs were randomized to receive either STD CPR (n = 7) or ACD CPR (n = 7). Both STD and ACD CPR were performed using an automated pneumatic piston device applied midsternum, designed to provide either active chest compression (1.5 to 2.0 in.) and decompression or only active compression of the chest at 80 compressions per minute and 50% duty cycle. Using radiolabeled microspheres, median total myocardial blood flow after 5 minutes of ventricular fibrillation was 14 (7 to 30, minimum to maximum) STD CPR versus 30 (9 to 46) mL.min-1 x 100 g-1 with ACD CPR (P < .05). Median cerebral blood flow was 15 (10 to 26) mL.min-1 x 100 g-1 with STD CPR and 30 (21 to 39) with ACD CPR (P < .01). When comparing STD with ACD CPR, aortic systolic (62 mm Hg [48 to 70] vs 80 [59 to 86]) and diastolic (22 [18 to 28] vs 28 [21 to 36]) pressures, calculated coronary systolic (30 [22 to 36] vs 49 [37 to 56]) and diastolic (18 [16 to 23] vs 26 [21 to 31]) perfusion pressures, end-tidal CO2 (1.4% [0.8 to 1.8] vs 2.1 (1.8 to 2.4]), cerebral O2 delivery (3.1 mL.min-1 x 100 g-1 [1.5 to 4.5] vs 5.3 [3.8 to 7.5]), and cerebral perfusion pressure (14 mm Hg [4 to 22] vs 26 [6 to 34]) were all significantly higher with ACD CPR: To compare these parameters before and after vasopressor therapy, a bolus of high-dose epinephrine (0.2 mg/kg) was given to all animals after 5 minutes of ventricular fibrillation. Organ blood flow and calculated perfusion pressures increased significantly in both the STD and ACD groups after epinephrine. The differences observed between STD and ACD CPR before epinephrine were diminished 90 seconds after epinephrine but were again statistically significant when assessed 5 minutes later, once the acute effects of epinephrine had decreased. No difference in short-term resuscitation success was found between the two groups. CONCLUSIONS We conclude that ACD CPR significantly increases myocardial and cerebral blood flow during cardiac arrest in the absence of vasopressor therapy compared with STD CPR:

Effect of vasopressin on hemodynamic variables, organ blood flow, and acid-base status in a pig model of cardiopulmonary resuscitation

Based upon the hypothesis that vasopressin (antidiuretic hormone) may increase vascular resistance during ventricular fibrillation, the effects of this potent vasoconstrictor were studied in a porcine model of ventricular fibrillation. Vasopressin therapy was compared to epinephrine by randomly allocating 14 pigs to receive either 0.045 mg/kg of epinephrine (n = 7) or 0.8 U/kg of vasopressin (n = 7) after 4 min of ventricular fibrillation and 3 min of open-chest cardiopulmonary resuscitation. During cardiopulmonary resuscitation, myocardial blood flow before and 90 s and 5 min after drug administration was 57 +/- 11, 84 +/- 11, and 59 +/- 9 mL.min-1 x 100 g-1 (mean +/- SEM) in the epinephrine group, and 61 +/- 5, 148 +/- 26, and 122 +/- 22 mL.min-1 x 100 g-1 in the vasopressin group (P < 0.05 at 90 s and 5 min). At the same times, mean cardiac index was not significantly different between the groups. After drug administration, coronary venous PCO2 was significantly higher and coronary venous pH was significantly lower in the epinephrine as compared to the vasopressin group. All pigs in both groups were resuscitated and survived the 2-h observation period. We conclude that vasopressin improves vital organ perfusion during ventricular fibrillation and cardiopulmonary resuscitation. Vasopressin seems to be at least as effective as epinephrine in this pig model of ventricular fibrillation.

Spectral analysis of ventricular fibrillation and closed-chest cardiopulmonary resuscitation

This study was designed to assess the interference by closed-chest cardiopulmonary resuscitation (CPR) on the ventricular fibrillation (VF) ECG signal in a porcine model of cardiac arrest and to elucidate which variable of VF spectral analysis reflects best myocardial blood flow and resuscitation success during CPR. Fourteen domestic pigs were allocated to receive either 0.4 U/kg vasopressin (n = 7) or 10 ml saline (n = 7) after 4 min of VF and 3 min of CPR. Using radiolabeled microspheres, myocardial blood flow was determined during CPR before, and 90 s and 5 min after, drug administration. Using spectral analysis of VF, the median frequency, dominant frequency, edge frequency and amplitude of VF were determined simultaneously and before the first defibrillation attempt. Using filters in order to specify frequency ranges, stepwise elimination of mechanical artifacts resulting from CPR revealed that at a frequency bandpass of 4.3-35 Hz, median fibrillation frequency has a sensitivity, specificity, positive and negative predictive value of 100% to differentiate between resuscitated and non-resuscitated animals. The best correlation between myocardial blood flow and fibrillation frequency was found at a median frequency range of 4.3-35 Hz. We conclude that spectral analysis of VF can provide reliable information relating to successful resuscitation. In this model after elimination of oscillations due to mechanical CPR, median fibrillation frequency best reflects the probability of resuscitation success.

Effects of graded doses of vasopressin on median fibrillation frequency in a porcine model of cardiopulmonary resuscitation: results of a prospective, randomized, controlled trial.

OBJECTIVE To assess the effects of graded doses of vasopressin vs. saline on median fibrillation frequency and defibrillation success in a porcine model of cardiopulmonary resuscitation. DESIGN Prospective, randomized, controlled trial. SETTING Animal laboratory in a university medical center. SUBJECTS Twenty-eight domestic pigs (body weight between 26 and 31 kg), aged 12 to 14 wks. INTERVENTIONS AND MAIN RESULTS After 4 mins of ventricular fibrillation and 3 mins of closed-chest cardiopulmonary resuscitation, the animals were allocated to receive either 0.2 U/kg of vasopressin (n = 7), 0.4 U/kg of vasopressin (n = 7), 0.8 U/kg of vasopressin (n = 7), or 10 mL of saline (n = 7, control group). Using radiolabeled microspheres, myocardial blood flow rates during cardiopulmonary resuscitation-before drug administration and 90 secs and 5 mins after drug administration-were as follows in the four groups (mean +/- SEM): 18.8 +/- 0.9, 17.2 +/- 1.1, and 14.6 +/- 1.4 mL/min/100 g in the control group; 17.8 +/- 2.2, 49.6 +/- 6.3 (p < .01 vs. control group), and 29.4 +/- 3.1 mL/min/100 g (p < .05 vs. control group) in the group receiving 0.2 U/kg of vasopressin; 17.1 +/- 1.0, 52.4 +/- 7.5 (p < .01 vs. control group), and 52.2 +/- 5.8 mL/min/100 g (p < .001 vs. control group) in the group receiving 0.4 U/kg of vasopressin; and 18.1 +/- 1.6, 94.9 +/- 9.2 (p < .001 vs. control group), and 57.2 +/- 6.3 mL/min/100 g (p < .001 vs. control group) in the group receiving 0.8 U/kg of vasopressin. Using spectral analysis, median frequencies of ventricular fibrillation-before drug administration and 90 secs and 5 mins after drug administration-were as follows in the four groups: 9.6 +/- 0.4, 8.5 +/- 0.8, and 7.2 +/- 1.0 Hz in the control group; 9.7 +/- 0.5, 12.9 +/- 0.8 (p < .01 vs. control group), and 12.7 +/- 0.8 Hz (p < .001 vs. control group) in the group receiving 0.2 U/kg of vasopressin; 10.3 +/- 0.2, 12.7 +/- 0.9 (p < .01 vs. control group), and 12.8 +/- 0.7 Hz (p < .001 vs. control group) in the group receiving 0.4 U/kg of vasopressin; and 10.0 +/- 0.9, 14.1 +/- 0.9 (p < .001 vs. control group), and 12.5 +/- 0.9 Hz (p < .001 vs. control group) in the group receiving 0.8 U/kg of vasopressin at the same points in time. Median frequency before the first defibrillation attempt was 12.3 +/- 0.4 Hz in the resuscitated animals (n = 19) and 8.2 +/- 1.2 Hz in the nonresuscitated animals (n = 9) (p < .001). CONCLUSIONS This study contributes to the characterization of the effect of increasing global myocardial blood flow on median fibrillation frequency after administration of graded doses of vasopressin in a porcine model of ventricular fibrillation. Interventions such as vasopressor treatment that increase fibrillation frequency improve the chance of successful defibrillation.

Effect of angiotensin II on myocardial blood flow and acid-base status in a pig model of cardiopulmonary resuscitation

The effect of angiotensin II on myocardial blood flow and acid-base status during cardiopulmonary resuscitation (CPR) was assessed. Fourteen pigs were allocated randomly to receive either 0.9% saline (n = 7) or 0.05 mg/kg angiotensin II (n = 7) after 4 min of ventricular fibrillation and 3 min of open-chest CPR. Total myocardial blood flow (measured with radiolabeled microspheres) before, 90 s, and 5 min following drug administration was 74 +/- 18, 62 +/- 12, and 54 +/- 11 mL.min-1 x 100g-1 (mean +/- SD) in the control, and 72 +/- 17, 125 +/- 25, and 74 +/- 20 mL.min-1 x 100 g-1 in the angiotensin II group (P < 0.001 at 90 s and P < 0.05 at 5 min). The PCO2 of coronary venous blood at 90 s after drug administration was 82 +/- 8 mm Hg in the control group as compared to 47 +/- 9 mm Hg in the angiotensin II group (P < 0.001). Only three of the seven control group animals could be resuscitated successfully, whereas all of the angiotensin II-treated pigs survived the 1-h observation period (P < 0.05), during which neither arterial hypertension nor bradycardia was observed. Angiotensin II was associated with an improvement of myocardial blood flow during CPR and short-term resuscitation success. The increase in myocardial perfusion is associated with a lower coronary venous PCO2 and a higher coronary venous pH. The authors conclude that angiotensin II administration facilitated cardiopulmonary resuscitation.

Concentrations of prolactin and prostaglandins during and after cardiopulmonary resuscitation.

OBJECTIVES To assess differences in plasma prolactin and prostaglandin concentrations in resuscitated and nonresuscitated patients during cardiopulmonary resuscitation (CPR), and to compare changes of prostaglandin and prolactin concentrations with hemodynamic variables in the immediate postresuscitation phase. DESIGN Prospective, descriptive study. SETTING Emergency medical service at a university hospital. PATIENTS Twenty-nine patients ranging in age from 39 to 87 yrs with out-of-hospital cardiac arrest. INTERVENTIONS Venous blood samples were taken during CPR and at 5, 15, 30, and 60 mins after restoration of spontaneous circulation in order to measure plasma concentrations of prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 by immunoassay. Heart rate and blood pressure were measured at 5, 15, 30, and 60 mins after restoration of spontaneous circulation. MEASUREMENTS AND MAIN RESULTS In 15 patients, restoration of spontaneous circulation was achieved; in the remaining 14 patients, successful resuscitation was not possible. During CPR, the mean plasma prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 concentrations were 95.9 +/- 13.6 micrograms/L, 357 +/- 61 ng/L, 228 +/- 28 ng/L, 277 +/- 66 ng/L, and 375 +/- 78 ng/L, respectively, in resuscitated patients, and 23.9 +/- 5.6 micrograms/L (p = .0001), 192 +/- 22 ng/L (p = .005), 202 +/- 31 ng/L (p = .528), 221 +/- 40 ng/L (p = .713), and 344 +/- 77 ng/L (p = .780), respectively, in nonresuscitated patients. At 60 mins after restoration of spontaneous circulation, the mean plasma prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 concentrations were 50.1 +/- 9.5 micrograms/L, 306 +/- 42 ng/L, 503 +/- 87 ng/L, 278 +/- 55 ng/L, and 355 +/- 30 ng/L, respectively. Mean values of systolic arterial blood pressure were 114 +/- 12 mm Hg at 30 mins and 123 +/- 18 mm Hg at 60 mins. No significant correlations were found between hemodynamic values and plasma concentrations of prolactin or prostaglandins. CONCLUSIONS Prolactin and prostaglandin concentrations were increased during cardiac arrest and CPR. Successful initial resuscitation was associated with increased prolactin and prostaglandin F2 alpha concentrations during CPR. Decreased concentrations in non-resuscitated patients may have been a result of exhaustion of the neuroendocrine and eicosanoid systems, or may be due to differences in bioavailability at the site of blood sampling based upon differences in hemodynamics.

Angiotensin II Augments Reflex Activity of the Sympathetic Nervous System During Cardiopulmonary Resuscitation in Pigs

BACKGROUND During hypotensive states, angiotensin II augments reflex activity of the sympathetic nervous system. The purpose of the present study was to assess the effects of this vasoconstrictor on myocardial blood flow and plasma catecholamine concentrations during and after CPR. METHODS AND RESULTS After 4 minutes of ventricular fibrillation and 3 minutes of open-chest CPR, 14 pigs (24 to 26 kg) were randomized into two groups receiving either saline (n = 7) or 0.05 mg/kg angiotensin II (n = 7). Arterial plasma catecholamine concentration was measured with high-pressure liquid chromatography. Organ blood flow was measured with radiolabeled microspheres. During CPR, after drug administration, left ventricular myocardial blood flow was significantly higher in the angiotensin II-treated group than in the control group. During CPR, median epinephrine concentrations before and 90 seconds and 5 minutes after drug administration were 63.0, 35.2, and 22.5 ng/mL, respectively, in the control group and 63.2, 139.8, and 154.2 ng/mL, respectively, in the angiotensin II group (P < .001 at 90 seconds and P < .01 at 5 minutes). At the same times, median norepinephrine concentrations were 52.6, 59.8, and 33.9 ng/mL, respectively, in the control group and 42.5, 98.7, and 111.3 ng/mL, respectively, in the angiotensin II group (P < .01 at 5 minutes). Restoration of spontaneous circulation was possible in all of the angiotensin II-treated pigs, whereas only 3 of the 7 saline-treated pigs could be resuscitated. At 5 minutes after successful resuscitation, epinephrine was 6.8 ng/mL in the control group and 16.1 ng/mL in the angiotensin II group (P < .05). CONCLUSIONS During CPR, angiotensin II appears to increase coronary perfusion pressure and myocardial blood flow, not only by direct peripheral arteriolar vasoconstriction via angiotensin II receptors but also by inducing a massive catecholamine release with adrenergic peripheral vasoconstriction.

Literature of resuscitationAngiotensin II augments reflex activity of the sympathetic nervous system during cardiopulmonary resuscitation in pigs: Circulation 1995; 92/4: 1020–1025

BACKGROUND During hypotensive states, angiotensin II augments reflex activity of the sympathetic nervous system. The purpose of the present study was to assess the effects of this vasoconstrictor on myocardial blood flow and plasma catecholamine concentrations during and after CPR. METHODS AND RESULTS After 4 minutes of ventricular fibrillation and 3 minutes of open-chest CPR, 14 pigs (24 to 26 kg) were randomized into two groups receiving either saline (n = 7) or 0.05 mg/kg angiotensin II (n = 7). Arterial plasma catecholamine concentration was measured with high-pressure liquid chromatography. Organ blood flow was measured with radiolabeled microspheres. During CPR, after drug administration, left ventricular myocardial blood flow was significantly higher in the angiotensin II-treated group than in the control group. During CPR, median epinephrine concentrations before and 90 seconds and 5 minutes after drug administration were 63.0, 35.2, and 22.5 ng/mL, respectively, in the control group and 63.2, 139.8, and 154.2 ng/mL, respectively, in the angiotensin II group (P < .001 at 90 seconds and P < .01 at 5 minutes). At the same times, median norepinephrine concentrations were 52.6, 59.8, and 33.9 ng/mL, respectively, in the control group and 42.5, 98.7, and 111.3 ng/mL, respectively, in the angiotensin II group (P < .01 at 5 minutes). Restoration of spontaneous circulation was possible in all of the angiotensin II-treated pigs, whereas only 3 of the 7 saline-treated pigs could be resuscitated. At 5 minutes after successful resuscitation, epinephrine was 6.8 ng/mL in the control group and 16.1 ng/mL in the angiotensin II group (P < .05). CONCLUSIONS During CPR, angiotensin II appears to increase coronary perfusion pressure and myocardial blood flow, not only by direct peripheral arteriolar vasoconstriction via angiotensin II receptors but also by inducing a massive catecholamine release with adrenergic peripheral vasoconstriction.