The pharmacokinetics of intraosseous atropine in hypovolemic swine

OBJECTIVE

Compare the pharmacokinetics of atropine administered via the intravenous (IV), intramuscular (IM), and intraosseous (IO) routes in a normovolemic and hypovolemic swine model.

DESIGN

Prospective, between subjects, experimental study.

SETTING

Vivarium.

SUBJECTS

Yorkshire-cross swine (N = 36).

INTERVENTION

Atropine was administered via IV, IM, or IO routes to normovolemic and hypovolemic swine. Blood samples were drawn at regular intervals after atropine administration and analyzed for plasma atropine concentration. Pharmacokinetic parameters were obtained from modeling the plasma concentrations.

MAIN OUTCOME MEASUREMENTS

Pharmacokinetic parameters, maximum concentration (Cmax) and time to maximum concentration (Tmax).

RESULTS

The IV and IO groups in both the normovolemic and hypovolemic models reached peak plasma concentration immediately and had a very rapid distribution phase with no apparent absorption phase for the IO groups. Peak plasma concentration and time to reach peak concentration were both significantly lower for the IM groups. There was a significant increase in absorption time with IM administration in the hypovolemic model compared to the normovolemic model.

CONCLUSION

The IO route is an effective method of administering atropine and is comparable to the IV route even under conditions of significant hemorrhage. Therapeutic levels of atropine may be delayed and possibly difficult to obtain via IM injection in the presence of hypovolemic shock.

Effects of sternal intraosseous and intravenous administration of Hextend on time of administration and hemodynamics in a swine model of hemorrhagic shock

OBJECTIVE

Disasters may cause traumatic injuries leading to hemorrhage. Hemorrhage is the leading cause of death for military and civilian trauma casualties. The US Army's Tactical Combat Casualty Care guidelines recommend administering a 500 mL Hextend bolus via the intravenous (IV) or intraosseous (IO) routes for patients in hypovolemic shock. The purposes of this study were to compare administration time of Hextend and the effects on hemodynamics when Hextend is administered by the sternal IO (SIO) and IV routes in a swine model of hemorrhagic shock.

DESIGN

This was a prospective, experimental study with random assignment.

SETTING

The study was implemented at an animal vivarium.

SUBJECTS

Yorkshire-cross (N=21) swine were used.

INTERVENTION

Each swine was hemorrhaged 30 percent of their total blood volume to simulate a class II hemorrhage; 500 mL of Hextend was administered by the SIO and IV routes after hemorrhage. The control group did not receive any resuscitative fluids.

MAIN OUTCOME MEASUREMENTS

The predetermined variables of the study were time of administration and hemodynamics over 8 minutes. Hemodynamic data were collected every 2 minutes until administration was complete.

RESULTS

There were no significant differences in the time to administer Hextend between the SIO (616±166 seconds) and the IV groups (534±151 seconds) (p=0.37). There were no significant differences between the SIO and IV groups relative to hemodynamics (p>0.05), but both were significantly different than the control group (p<0.05).

CONCLUSION

The SIO route is an effective method of administering Hextend.

The effects of QuikClot Combat Gauze on hemorrhage control when used in a porcine model of lethal femoral injury

OBJECTIVES

The aims of the study were to 1) determine the effectiveness of QuikClot Combat Gauze (QCG); 2) determine the arterial blood pressure at which rebleeding occurs; 3) determine how much intravenous fluid could be administered before hemorrhage reoccurred, and 4) determine the number extremity movement on rebleeding when QCG was used.

DESIGN

This was a prospective, randomized, experimental study.

SUBJECTS

Adult Yorkshire pigs were randomly assigned to two groups QCG (n = 10) or control (n = 10).

INTERVENTION

After the swine were anesthetized, the investigators transected the femoral artery and vein. After 1 minute of uncontrolled bleeding, QCG was placed in the wound followed by standard wound packing. The control group underwent the same procedures without QCG. After 5 minutes of firm, manual pressure, a pressure dressing was applied. Following 30 minutes, the dressings were removed and blood loss was calculated. If hemostasis occurred, phenylephrine was administered until there was rebleeding. If no bleeding, up to 5 L of IV crystalloid was administered until there was hemorrhage. If no bleeding, the extremity on the side of the hemorrhage was moved through flexion, extension, abduction, and adduction 10 times or until rebleeding occurred.

MAIN OUTCOMES

QCG compared to a control was more effective in controlling hemorrhage, withstanding increases in systolic blood pressure, more latitude in resuscitation fluid, and movement (p < 0.05).

The Effects of Movement on Hemorrhage When QuikClot® Combat Gauze™ Is Used in a Hypothermic Hemodiluted Porcine Model

BACKGROUND

The purpose of this study was to compare the effectiveness of QuikClot(®) Combat Gauze™ (QCG) to a control wound dressing to withstand movement in a porcine model with hemodilution and hypothermia.

DESIGN

This was a prospective study with a between-subjects experimental design. Twenty-six Yorkshire swine were randomly assigned to two groups: QCG (n = 13) or a control dressing (n = 13).

METHODS

The subjects were exsanguinated to 30% of the blood volume; hypothermia was induced for 10 minutes. The hemostatic agent, QCG, was placed into the wound, followed by standard wound packing. If hemostasis was achieved, 5L of crystalloid solution were rapidly administered intravenously, and the wound was again observed for rebleeding. If no bleeding occurred, the extremity on the side of the injury was systematically moved through flexion, extension, abduction, and adduction sequentially 10 times or until rebleeding occurred.

RESULTS

An independent t test indicated there were significant differences in the number of movements before rebleeding between the QCG group (mean ± standard deviation [SD], 32.92 ± 14.062) and the control group (mean ± SD, 6.15 ± 15.021) (p < .0001).

CONCLUSION

QCG produces a robust clot that can withstand more movement than a control dressing.

The effects of QuikClot Combat Gauze on hemorrhage control in the presence of hemodilution and hypothermia

Hemorrhage is the leading cause of death from trauma. Intravenous (IV) fluid resuscitation in these patients may cause hemodilution and secondary hemorrhage. In addition, hypothermia may interfere with coagulation. The purposes of this study were to compare the effectiveness QuikClot Combat Gauze (QCG) to a control group on hemorrhage in a hemodiluted, hypothermic model, and to determine the effects of IV volume resuscitation on rebleeding. This was a prospective, between subjects, experimental design. Yorkshire swine were randomly assigned to two groups: QCG (n = 13) or control (n = 13). The subjects were anesthetized. Hypothermia (temperature of ≤34.0 °C) was induced; 30% of their blood volume was exsanguinated. A 3:1 replacement of Lactated Ringer's was administered to dilute the remaining blood. The femoral artery and vein were transected. After 1 min of uncontrolled hemorrhage, QCG was placed into the wound followed by standard wound packing. The control group underwent the same procedures without QCG. After 5 min of manual pressure, a pressure dressing was applied. Following 30 min, the dressings were removed, and blood loss was calculated. For subjects achieving hemostasis, up to 5 L of IV fluid was administered or until bleeding occurred, which was defined as >2% total blood volume. The QCG had significantly less hemorrhage than the control (QCG = 30 ± 99 mL; control = 404 ± 406 mL) (p = .004). Further, the QCG group was able to tolerate more resuscitation fluid before hemorrhage (QCG = 4615 ± 1386 mL; control = 846 ± 1836) (p = .000).

Comparison of muscle paralysis after intravenous and intraosseous administration of succinylcholine in Swine

AIM

To compare the onset and duration of intravenous (IV) and intraosseous (IO) administration of succinylcholine in swine.

METHODS

Electromyographic (EMG) amplitudes were used to characterize muscle paralysis following administration of succinylcholine via the IV or IO route in four Yorkshire-cross swine.

RESULTS

The onset of action of succinylcholine was statistically longer after IO administration (0.97±0.40) compared with IV administration (0.55±0.26) (p=.048). Duration of action was unaffected by route of administration: IO, 11.4±4.2, and IV, 12.9±3.8 (p=.65).

CONCLUSIONS

Succinylcholine can be effectively administered via the IO route. However, an increased dose may be necessary when administering succinylcholine via the IO route to achieve the same rapid onset as standard IV dosing.

Effects of intraosseous and intravenous administration of Hextend® on time of administration and hemodynamics in a Swine model

INTRODUCTION

The military recommends that a 500 mL bolus of Hextend® be administered via an intravenous (IV) 18-gauge needle or via an intraosseous (IO) needle for patients in hypovolemic shock.

PURPOSES

The purposes of this study were to compare the time of administration of Hextend and the hemodynamics of IV and IO routes in a Class II hemorrhage swine model.

METHODS

This was an experimental study using 27 swine. After 30% of their blood volume was exsanguinated, 500 mL of Hextend was administered IV or IO, but not to the control group. Hemodynamic data were collected every 2 minutes until administration was complete.

RESULTS

Time for administration was not significant (p=.78). No significant differences existed between the IO and IV groups relative to hemodynamics (p>.05), but both were significantly different than the control group (p<.05).

CONCLUSIONS

The IO route is an effective method of administering Hextend.

The Effects of QuikClot Combat Gauze, Fluid Resuscitation, and Movement on Hemorrhage Control in a Porcine Model

The purpose of this study was to compare the effectiveness of QuikClot Combat Gauze (QCG) compared to a control group on hemorrhage control; the amount of crystalloid volume infusion on rebleeding; the effect of movement on hemorrhage. This was a prospective, experimental design. Swine were randomly assigned to either the QCG () or the control group (). Investigators transected the femoral artery and vein in each swine. After one minute of uncontrolled hemorrhage, the hemostatic agent, QCG, was placed into the wound followed by standard wound packing. The control group underwent the same procedures but without a hemostatic agent. After five minutes of direct pressure, a standard pressure dressing was applied. After 30 minutes, dressings were removed, and the wound was observed for rebleeding for 5 minutes. If hemostasis occurred, 5 liters of crystalloid was given over 5 minutes, and the wound was observed for rebleeding for 5 additional minutes. If no bleeding occurred, the extremity on the side of the injury was moved. There were significant differences in the amount of hemorrhage (), the amount of fluid administration (), and the number of movements () between the QCG and control.

The effects of QuikClot Combat Gauze on hemorrhage control in the presence of hemodilution

INTRODUCTION

Although hemostatic agents may be effective at stopping hemorrhage, they may fail because of hemodilution from intravenous fluids. The purpose of this study was to investigate the effects of QuikClot Combat Gauze (QCG) on rebleeding in a class II hemorrhage in the presence of hemodilution in a lethal femoral injury.

METHODS

This was a prospective experimental, between swine subjects design. Pigs were assigned to one of two groups: QCG (n=15) or control (n=15). Thirty percent of the pig's blood was exsanguinated and then a 3:1 ratio of ringers lactate was administered. A groin injury was created by transecting the femoral artery and vein to simulate a battlefield injury and allowed to bleed for one minute. After one minute of hemorrhage, proximal pressure was applied to the injury, and QCG was placed into the wound followed by standard wound packing. The control group underwent the same procedures with the exception of the hemostatic agent. For both groups, 5 minutes of direct pressure was applied to the wound followed by a standard pressure dressing. Dressings were removed after 30 minutes, and the amount of hemorrhage was calculated in milliliters for each group for a period of 5 minutes. An activated clotting time was used to exclude any pigs with coagulation pathology.

RESULTS

A multivariate analysis of variance indicated that there were no significant differences in the groups relative to weight, amount of one minute hemorrhage, fluid deficit replacement, blood volume, and the activated clotting time (P>.05) indicating that the groups were equivalent on these parameters. A t test indicated that there was significantly less bleeding (P=.002) in the QCG group (36 mL±112 mL) compared to the control group (340 mL±297 ml).

CONCLUSION

QCG produces a robust clot that can more effectively tolerate hemodilution compared to a control group.

The effects of BleedArrest on hemorrhage control in a porcine model

The purpose of this study was to examine the effectiveness of the hemostatic agent BleedArrest compared to control. This was a prospective, experimental design employing an established porcine model of uncontrolled hemorrhage. The minimum number of animals (n=10 per group) was used to obtain a statistically valid result. There were no statistically significant differences between the groups (P>.05) indicating that the groups were equivalent on the following parameters: activating clotting time, the subject weights, core body temperatures, amount of one minute hemorrhage, arterial blood pressures, and the amount and percentage of total blood volume. There were significant differences in the amount of hemorrhage (P=.033) between the BleedArrest (mean=72, SD±72 mL) and control (mean=317.30, SD±112.02 mL). BleedArrest is statistically and clinically superior at controlling hemorrhage compared to the standard pressure dressing control group. In conclusion, BleedArrest is an effective hemostatic agent for use in civilian and military trauma management.

Effects of using simulation versus CD-ROM in the performance of ultrasound-guided regional anesthesia

The purpose of this study was to determine which method of teaching, CD-ROM, simulation, or a combination of both, was more effective in increasing the performance of ultrasound-guided regional anesthesia. No studies have investigated these methods. The framework for this study was critical thinking. The study was a prospective, mixed (between and within) subjects, experimental design. The sample consisted of 29 student registered nurse anesthetists randomly assigned to 1 of 3 groups: CD-ROM (n = 11), simulation (n = 11), and combination (n = 7). All groups were evaluated by the use of cadavers before and 2 months after the intervention using a valid and reliable instrument of performance. A repeated-measures analysis of variance indicated that the combination was significantly better than the CD-ROM and simulation (P < .05). The means and standard deviations for pretest and posttest results, respectively, were: CD-ROM, 33 +/- 7%, 41 +/- 9%; simulation, 35 +/- 10%, 49 +/- 13%; and combination, 36 +/- 8%, 64 +/- 17%. The baseline for each group was 0. Use of a combination of CD-ROM and simulation should be considered in teaching ultrasound-guided regional anesthesia techniques.

Comparison of tibial intraosseous, sternal intraosseous, and intravenous routes of administration on pharmacokinetics of epinephrine during cardiac arrest: a pilot study

The purpose of this study was to determine and compare the maximum concentration (C(max)) and time to maximum concentration (T(max)) of epinephrine administered via tibial intraosseous (IO), sternal IO, and intravenous (i.v.) routes in a porcine model of cardiac arrest during cardiopulmonary resuscitation. Five pigs each were randomly assigned to 3 groups: tibial IO, sternal IO, and i.v. Cardiac arrest was induced with i.v. potassium chloride. After 2 minutes, cardiopulmonary resuscitation was initiated. Epinephrine was administered to each animal, and serial blood samples were collected over the next 3 minutes. Enzyme-linked immunosorbent assay was used to determine the epinephrine concentration. Multivariate analysis of variance helped determine if there were statistically significant differences between groups. There were significant differences in Cmax between the sternal IO and i.v. (P = .009) and tibial IO and i.v. (P = .03) groups but no significant difference between tibial and sternal IO groups (P = .75). Significant differences existed in Tmax between the tibial IO and i.v. (P = .04) and between tibial IO and sternal IO (P = .02) groups but no difference between the sternal IO and i.v. groups (P = .56). Intravenous administration of 1 mg of epinephrine resulted in a serum concentration 5.87 and 2.86 times greater than for the tibial and sternal routes, respectively.

The effects of arterial blood pressure on rebleeding when BleedArrest, Celox and TraumaDex are used in a porcine model of lethal femoral injury

Uncontrolled bleeding remains the leading cause of preventable death in trauma. Hemostatic agents are effective in hemorrhage control but often fail following high-volume crystalloid resuscitation. Aggressive fluid resuscitation increases the blood pressure which may dislodge the newly formed clot causing rebleeding. The purpose of this study was to determine the systolic blood pressure (SBP) and the mean arterial pressure (MAP) at which rebleeding occurs when a clot is formed by one of these hemostatic agents (BleedArrest, TraumaDex, or Celox) compared to a control group. This was a prospective, experimental study using male 5 Yorkshire swine per group (BleedArrest, TraumaDex, Celox, or control). The femoral artery and vein were transected to simulate a traumatic injury. Subjects were allowed to bleed for 60 seconds then one of the agents was poured into the wound. The control group underwent the same procedures but without the hemostatic agent. After 30 minutes, dressings were removed and the SBP was increased incrementally using intravenous phenylephrine until rebleeding occurred or until the arterial blood pressure reached 210 mm/Hg. The SBP and MAP were significantly higher in the BleedArrest, TraumaDex, and Celox groups compared to a control group (p < 0.05).

Effects of the HEET garment in the prevention of hypothermia in a porcine model

BACKGROUND

Hypothermia is a common battlefield trauma occurrence. This study compared the effectiveness of the hypothermia, environmental, exposure, and trauma (HEET) garment (Trident Industries, Beaufort, SC) with and without thermal inserts with a control group of two wool blankets in the prevention of hypothermia in a treated hypovolemic porcine model.

MATERIALS AND METHODS

Five female swine (Sus scrofa-Yorkshire cross) were assigned to each of three groups: HEET with thermal inserts (n=5); HEET without thermal inserts (n=5); or control (n=5). After the animals were anesthetized and stabilized for 30 min, the swine were hemorrhaged to a mean arterial pressure (MAP) of 30 mm Hg, simulating a battlefield injury. Hetastarch 6% (500 mL) was rapidly administered, simulating initial field resuscitation. One hour later, the animals' shed blood was reinfused, simulating transfusion at a field medical facility. The investigators moved the animal into a cooler set at 10°C ± 0.5°C. A pulmonary artery catheter was used to monitor core body temperature over a 6-h period.

RESULTS

A repeated measures ANOVA and Tukey's post hoc test were used to analyze the data. There was a significant difference between the groups. At the end of 6h, the mean core temperature for the HEET with inserts group was 32.69°C ± 1.5; the HEET without inserts, 31.02°C ± 1.8; and control, 34.78°C ± 1.2 (P<0.05). While all groups became hypothermic, the wool blanket group was most effective in maintaining body temperature closer to normothermia.

CONCLUSION

The HEET garments with and without heaters are ineffective in preventing hypothermia.