Effects of Endotracheal Epinephrine on Pharmacokinetics and Survival in a Swine Pediatric Cardiac Arrest Model.

OBJECTIVES: The aim of this study was to compare the endotracheal tube (ET) and intravenous (IV) administration of epinephrine relative to concentration maximum, time to maximum concentration, mean concentration over time (MC), area under the curve, odds, and time to return of spontaneous circulation (ROSC) in a normovolemic pediatric cardiac arrest model. METHODS: Male swine weighing 24-37 kg were assigned to 4 groups: ET (n = 8), IV (n = 7), cardiopulmonary resuscitation (CPR) + defibrillation (CPR + Defib) (n = 5), and CPR only (n = 3). Swine were placed arrest for 2 minutes, and then CPR was initiated for 2 minutes. Epinephrine (0.1 mg/kg) for the ET group or 0.01 mg/kg for the IV was administered every 4 minutes or until ROSC. Defibrillation started at 3 minutes and continued every 2 minutes for 30 minutes or until ROSC for all groups except the CPR-only group. Blood samples were collected over a period of 5 minutes. RESULTS: The MC of plasma epinephrine for the IV group was significantly higher at the 30- and 60-second time points (P = 0.001). The ET group had a significantly higher MC of epinephrine at the 180- and 240-second time points (P < 0.05). The concentration maximum of plasma epinephrine was significantly lower for the ET group (195 ± 32 ng/mL) than for the IV group (428 ± 38 ng/mL) (P = 0.01). The time to maximum concentration was significantly longer for the ET group (145 ± 26 seconds) than for the IV group (42 ± 16 seconds) (P = 0.01). No significant difference existed in area under the curve between the 2 groups (P = 0.62). The odds of ROSC were 7.7 times greater for the ET versus IV group. Time to ROSC was not significantly different among the IV, ET, and CPR + Defib groups (P = 0.31). CONCLUSIONS: Based on the results of this study, the ET route of administration should be considered a first-line intervention.

Tibial Intraosseous Administration of Epinephrine Is Effective in Restoring Return of Spontaneous Circulation in a Pediatric Normovolemic But Not Hypovolemic Cardiac Arrest Model.

OBJECTIVE: We compared the efficacy of tibial intraosseous (TIO) administration of epinephrine in a pediatric normovolemic versus hypovolemic cardiac arrest model to determine the incidence of return of spontaneous circulation (ROSC) and plasma epinephrine concentrations over time. METHODS: This experimental study evaluated the pharmacokinetics of epinephrine and/or incidence of ROSC after TIO administration in either a normovolemic or hypovolemic pediatric swine model. RESULTS: All subjects in the TIO normovolemia cardiac arrest group experienced ROSC after TIO administration of epinephrine. In contrast, subjects experiencing hypovolemia and cardiac arrest were significantly less likely to experience ROSC when epinephrine was administered TIO versus intravenous (TIO hypovolemia: 14% [1/7] vs IV hypovolemia: 71% [5/7]; P = 0.031). The TIO hypovolemia group exhibited significantly lower plasma epinephrine concentrations versus IV hypovolemia at 60, 90, 120, and 150 seconds (P < 0.05). Although the maximum concentration of plasma epinephrine was similar, the TIO hypovolemia group exhibited significantly slower time to maximum concentration times versus TIO normovolemia subjects (P = 0.004). CONCLUSIONS: Tibial intraosseous administration of epinephrine reliably facilitated ROSC among normovolemic cardiac arrest pediatric patients, which is consistent with published reports. However, TIO administration of epinephrine was ineffective in restoring ROSC among subjects experiencing hypovolemia and cardiac arrest. Tibial intraosseous-administered epinephrine during hypovolemia and cardiac arrest may have resulted in a potential sequestration of epinephrine in the tibia. Central or peripheral intravascular access attempts should not be abandoned after successful TIO placement in the resuscitation of patients experiencing concurrent hypovolemia and cardiac arrest.

Humerus Intraosseous and Intravenous Administration of Epinephrine in Normovolemic and Hypovolemic Cardiac Arrest Porcine Models.

OBJECTIVE: The aim of this study was to compare area under the curve (AUC), frequency, and odds of return of spontaneous circulation (ROSC) when epinephrine was administered in hypovolemic and normovolemic cardiac arrest models. METHODS: Twenty-eight adult swine were randomly assigned to 4 groups: HIO Normovolemia Group (HIONG); HIO Hypovolemia Group (HIOHG); IV Normovolemia (IVNG); and IV Hypovolemia Group (IVHG). Swine were anesthetized. The HIOH and IVH subjects were exsanguinated 35% of their blood volume. Each was placed into arrest. After 2 minutes, cardiopulmonary resuscitation was initiated. After another 2 minutes, 1 mg of epinephrine was given by IV or HIO routes; blood samples were collected over 5 minutes and analyzed by high-performance liquid chromatography. Subjects were defibrillated every 2 minutes. RESULTS: The AUC in the HIOHG was significantly less than both the HIONG (p = 0.047) and IVHG (p = 0.021). There were no other significant differences in the groups relative to AUC (p > 0.05). HIONG had a significantly higher occurrence of ROSC compared to HIOHG (p = 0.018) and IVH (p =0.018) but no other significant differences (p > 0.05). The odds of ROSC were 19.2 times greater for HIONG compared to the HIOHG. CONCLUSION: The study strongly supports the effectiveness of HIO administration of epinephrine and should be considered as a first-line intervention for patients in cardiac arrest related to normovolemic causes. However, our findings do not support using HIO access for epinephrine administration for patients in cardiac arrest related to hypovolemic reasons.

Effects of humeral intraosseous epinephrine in a pediatric hypovolemic cardiac arrest porcine model.

BACKGROUND: Aims of the study were to determine the effects of humerus intraosseous (HIO) versus intravenous (IV) administration of epinephrine in a hypovolemic, pediatric pig model. We compared concentration maximum (Cmax), time to maximum concentration (Tmax), mean concentration (MC) over time and return of spontaneous circulation (ROSC). METHODS: Pediatric pig were randomly assigned to each group (HIO (n=7); IV (n=7); cardiopulmonary resuscitation (CPR)+defibrillation (defib) (n=7) and CPR-only group (n=5)). The pig were anesthetized; 35% of the blood volume was exsanguinated. pigs were in arrest for 2 min, and then CPR was performed for 2 min. Epinephrine 0.01 mg/kg was administered 4 min postarrest by either route. Samples were collected over 5 min. After sample collection, epinephrine was administered every 4 min or until ROSC. The Cmax and MC were analyzed using high-performance liquid chromatography. Defibrillation began at 3 min postarrest and administered every 2 min or until ROSC or endpoint at 20 min after initiation of CPR. RESULTS: Analysis indicated that the Cmax was significantly higher in the IV versus HIO group (p=0.001). Tmax was shorter in the IV group but was not significantly different (p=0.789). The MC was significantly greater in the IV versus HIO groups at 90 and 120 s (p<0.05). The IV versus HIO had a significantly higher MC (p=0.001). χ2 indicated the IV group (5 out of 7) had significantly higher rate of ROSC than the HIO group (1 out of 7) (p=0.031). One subject in the CPR+defib and no subjects in the CPR-only groups achieved ROSC. DISCUSSION: Based on the results of our study, the IV route is more effective than the HIO route.

Humerus intraosseous administration of epinephrine in normovolemic and hypovolemic porcine model.

OBJECTIVE: Compare the maximum concentration (Cmax), time to maximum concentration (Tmax), mean concentration, rate of return of spontaneous circulation (ROSC), time to ROSC, and odds of ROSC when epinephrine is administered by humerus intraosseous (HIO) compared to intravenous (IV) routes in both a hypovolemic and normovolemic cardiac arrest model. DESIGN: Prospective, between subjects, randomized experimental study. SETTING: TriService Facility. SUBJECTS: Twenty-eight adult Yorkshire Swine were randomly assigned to four groups: HIO normovolemia; HIO hypovolemia; IV normovolemia; and IV hypovolemia. INTERVENTION: Swine were anesthetized. The hypovolemic group was exsanguinated 31 percent of their blood volume. Subjects were placed into arrest. After 2 minutes, cardiopulmonary resuscitation (CPR) was initiated. After another 2 minutes, 1 mg epinephrine was given by IV or HIO routes; blood samples were collected over 4 minutes. Hypovolemic groups received 500 mL of 5 percent albumin following blood sampling. CPR continued until ROSC or for 30 minutes. MAIN OUTCOME MEASURES: ROSC, time to ROSC, Cmax, Tmax, mean concentrations over time, odds of ROSC. RESULTS: Cmax was significantly higher, the Tmax, and the time to ROSC were significantly faster in the HIO normovolemic compared to the HIO hypovolemic group (p < 0.05). All seven in the HIO normovolemic group achieved ROSC compared to three of the HIO hypovolemic group. Odds of ROSC were 19.2 times greater in the HIO normovolemic compared the HIO hypovolemic group. CONCLUSION: The HIO is an effective route in a normovolemic model. However, the findings indicate that sufficient blood volume is essential for ROSC in a hypovolemic scenario.

Sternal Route More Effective than Tibial Route for Intraosseous Amiodarone Administration in a Swine Model of Ventricular Fibrillation.

OBJECTIVE: The pharmacokinetics of IO administered lipid soluble amiodarone during ventricular fibrillation (VF) with ongoing CPR are unknown. This study measured mean plasma concentration over 5 minutes, maximum plasma concentration (Cmax), and time to maximum concentration (Tmax) of amiodarone administered by the sternal IO (SIO), tibial IO (TIO), and IV routes in a swine model of VF with ongoing CPR. METHODS: Twenty-one Yorkshire-cross swine were randomly assigned to three groups: SIO, TIO, and IV. Ventricular fibrillation was induced under general anesthesia. After 4 minutes in VF, 300 mg amiodarone was administered as indicated by group assignment. Serial blood specimens collected at 30, 60, 90, 120, 150, 180, 240, and 300 seconds were analyzed using high performance liquid chromatography with tandem mass spectrometry. RESULTS: The mean plasma concentration of IV amiodarone over 5 minutes was significantly higher than the TIO group at 60 seconds (P = 0.02) and 90 seconds (P = 0.017) post-injection. No significant differences in Cmax between the groups were found (P <0.05). The Tmax of amiodarone was significantly shorter in the SIO (99 secs) and IV (86 secs) groups compared to the TIO group (215 secs); P = 0.002 and P = 0.002, respectively. CONCLUSIONS: The SIO and IV routes of amiodarone administration were comparable. The TIO group took nearly three times longer to reach Tmax than the SIO and IV groups, likely indicating depot of lipid-soluble amiodarone in adipose-rich tibial yellow bone marrow. The SIO route was more effective than the TIO route for amiodarone delivery in a swine model of VF with ongoing CPR. Further investigations are necessary to determine if the kinetic differences found between the SIO and TIO routes in this study affect survival of VF in humans.

Comparison of the effects of sternal and tibial intraosseous administered resuscitative drugs on return of spontaneous circulation in a swine model of cardiac arrest.

OBJECTIVE: Compare vasopressin, amiodarone, and epinephrine administration by sternal intraosseous (SIO), tibial intraosseous (TIO), and intravenous (IV) routes in a swine model of cardiac arrest. DESIGN: Prospective, randomized, between subjects, experimental design. SETTING: Laboratory. SUBJECTS: Male Yorkshire-cross swine (N = 35), seven per group. INTERVENTION: Swine were randomized to SIO, TIO, IV, cardiopulmonary resuscitation (CPR) with defibrillation, or CPR-only groups. Ventricular fibrillation (VF) was induced under general anesthesia. Mechanical CPR began 2 minutes postarrest. Vasopressin (40 U) was administered to the SIO, TIO, and IV groups 4 minutes postarrest. Defibrillation was performed and amiodarone (300 mg) was administered 6 minutes postarrest. Defibrillation was repeated, and epinephrine (1 mg) was administered 10 minutes postarrest. Defibrillation was repeated every 2 minutes and epinephrine repeated every 4 minutes until return of spontaneous circulation (ROSC) or 26 postarrest minutes elapsed. MAIN OUTCOME MEASURES: Rate of ROSC, time to ROSC, and odds of ROSC. RESULTS: There were no significant differences in rate of ROSC between the SIO and TIO (p = 0.22) or IV groups (p = 1.0). Time to ROSC was five times less in the SIO group than the TIO group (p = 0.003) but not compared to IV (p = 0.125). Time to ROSC in the IV group was significantly less than the TIO group (p = 0.04). Odds of ROSC for the SIO group were five times higher compared to the TIO group but same as IV. Odds of ROSC in the IV group were higher than the TIO group. CONCLUSION: There was a statistically significant delay in the time to ROSC and a clinically significant difference in odds of ROSC when resuscitative drugs, including lipophilic amiodarone, were administered by the TIO route compared to the SIO and IV routes in a swine model of sudden cardiac arrest. Further investigations are warranted to isolate the mechanism behind these findings.

Effects of intravenous, sternal, and humerus intraosseous administration of Hextend on time of administration and hemodynamics in a hypovolemic swine model.

OBJECTIVE: To determine if there were significant differences among humerus intraosseous (HIO), sternal intraosseous (SIO), and intravenous (IV) administration of 500 mL Hextend in hemodynamics or administration time in a hypovolemic swine model. SETTING: Vivarium. SUBJECTS: Yorkshire swine; sample size was based on a large effect size of 0.5, an α of 0.05, and a power of 80 percent Swine were randomly assigned to one of four groups: HIO (n = 9), SIO (n = 9), IV (n = 9), and control (n = 9). INTERVENTION: Swine were exsanguinated 30 percent of their blood volume. Hextend (500 mL) was administered by either the HIO, SIO, or IV route; the control group received none. MAIN OUTCOME: Time of administration of Hextend; systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), and stroke volume (SV) data were collected every 2 minutes and compared by group over 8 minutes. RESULTS: A repeated analysis of variance found that there were no significant differences in SBP, DBP, MAP, HR, CO, and SV among HIO, SIO, and IV groups over 8 minutes (p > 0.05). An analyses of variance determined that there was no significant difference between groups relative to time of administration (p = 0.521). CONCLUSION: When IV access is difficult, both HIO and SIO are effective techniques for rapid vascular access and the administration of Hextend for patients in hypovolemic shock.

Effects of tibial and humerus intraosseous and intravenous vasopressin in porcine cardiac arrest model.

OBJECTIVE: Compare maximum concentration (Cmax), time to maximum concentration (Tmax), mean serum concentration of vasopressin, return of spontaneous circulation (ROSC), time to ROSC, and odds of survival relative to vasopressin administration by tibial intraosseous (TIO), humerus intraosseous (HIO), and intravenous (IV) routes in a hypovolemic cardiac arrest model. DESIGN: Prospective, between subjects, randomized experimental design. SETTING: TriService Research Facility. SUBJECTS: Yorkshire-cross swine (n = 40). INTERVENTION: Swine were anesthetized, exsanguinated to a Class III hemorrhage, and placed into cardiac arrest. After 2 minutes, cardiopulmonary resuscitation was initiated. After an additional 2 minutes, a dose of 40 units of vasopressin was administered by TIO, HIO, or the IV routes. Blood samples were collected over 4 minutes and analyzed by high-performance liquid chromatography tandem mass spectrometry. MAIN OUTCOME MEASUREMENTS: ROSC, time to ROSC, Cmax, Tmax, mean concentrations over time, and odds ratio. RESULTS: There was no significant difference in rate of ROSC or time to ROSC between the TIO, HIO, and IV groups (p > 0.05). The Cmax was significantly higher in the IV group compared to the TIO group (p = 0.015), but no significant difference between the TIO versus HIO or HIO versus IV groups (p > 0.05). The Tmax was significantly shorter for the HIO compared to the TIO group (p = 0.034), but no significant differences between the IV group compared to the TIO or HIO groups (p > 0.05). The odds of survival were higher in the HIO group compared to all other groups. CONCLUSION: The TIO and HIO provide rapid and reliable access to administer life-saving medications during cardiac arrest.