Vasopressor Therapy Using Vasopressin Prior to Crystalloid Resuscitation in Irreversible Hemorrhagic Shock under Isoflurane Anesthesia in Dogs

Assessment of the hypothalamic-pituitary-adrenocortical axis function using a vasopressin stimulation test in neonatal foals

BACKGROUND

Bacterial sepsis is the leading cause of death in foals and is associated with hypothalamic-pituitary-adrenocortical axis (HPAA) dysfunction. HPAA function can be evaluated by an arginine-vasopressin (AVP) stimulation test.

HYPOTHESES/OBJECTIVES

Administration of AVP will stimulate a dose-dependent rise in systemic adrenocorticotropin-releasing hormone (ACTH) and cortisol in neonatal foals. There will be no response seen in corticotropin-releasing hormone (CRH) and baseline AVP will be within reference interval.

ANIMALS

Twelve neonatal foals, <72 hours old.

METHODS

HPAA function was assessed in foals utilizing 3 doses of AVP (2.5, 5, and 7.5 IU), administered between 24 and 48 hours of age in this randomized cross-over study. Cortisol, ACTH, CRH and AVP were measured at 0 (baseline), 15, 30, 60 and 90 minutes after AVP administration with immunoassays. The fold increase in cortisol and ACTH was calculated at 15 and 30 minutes compared to baseline.

RESULTS

All doses of AVP resulted in a significant increase in cortisol concentration over time, and a dose-dependent increase in ACTH concentration over time. ACTH and cortisol were significantly increased at 15 and 30 minutes, respectively after all 3 doses of AVP compared to baseline (P < .01). There was no change in endogenous CRH after stimulation with AVP.

CONCLUSION AND CLINICAL IMPORTANCE

Administration of AVP is safe and results in a significant rise in ACTH and cortisol in neonatal foals. A stimulation test with AVP (5 IU) can be considered for HPAA assessment in septic foals.

A Comparison of Dobutamine, Norepinephrine, Vasopressin, and Hetastarch for the Treatment of Isoflurane-Induced Hypotension in Healthy, Normovolemic Dogs

Isoflurane is a commonly used inhalation anesthetic in species undergoing veterinary care that induces hypotension, impacting organ perfusion, making it imperative to minimize its occurrence or identify effective strategies for treating it. This study evaluated and compared the hemodynamic effects of DOB, NEP, VAS, and HES in twelve isoflurane-anesthetized Beagle dogs. The order of the first three treatments was randomized. HES was administered last. Data were collected before treatments (baseline) and after 10 min of a sustained MAP of <45 mmHg induced by a high end-tidal isoflurane concentration (T0). Once treatment was initiated and the target MAP was achieved (65 to 80 mmHg) or the maximum dose reached, data were collected after 15 min of stabilization (T1) and 15 min after (T2). A 15 min washout period with a MAP of ≥65 mmHg was allowed between treatments. The intravenous dosage regimens started and were increased by 50% every five minutes until the target MAP or maximum dose was reached. The dosages were as follows: DOB, 5-15 μg/kg/min; NEP, 0.1-2 μg/kg/min; VAS, 0.5-5 mU/kg/min; and HET, 6% 1-20 mL/kg/min. DOB improved CO, DO2, and VO2, but reduced SVR. VAS elevated SVR, but decreased CO, DO2, and VO2. HES minimally changed BP and mildly augmented CO, DO2, and VO2. These treatments failed to reach the target MAP. NEP increased the arterial BP, CO, MPAP, and PAWP, but reduced HR. Norepinephrine infusion at 0.44 ± 0.19 μg/kg/min was the most efficient therapy for correcting isoflurane-induced hypotension.

Patterns of vasopressor utilization during the resuscitation of massively transfused trauma patients

BACKGROUND

The use of vasopressors (VP) in the resuscitation of massively transfused trauma patients might be considered a marker of inadequate resuscitation. We sought to characterize the utilization of VP in patients receiving massive transfusion and examine the association of their use with mortality.

METHODS

Trauma patients admitted from January 2011 to October 2016 receiving massive transfusion, defined as 3 units of pRBC within the first hour from admission, were selected for analysis. Demographics, admission vital signs and labs, use of VP, surgical interventions and outcomes were collected. Standard statistical tools were utilized.

RESULTS

Over the 5-year study period, 120 trauma patients met inclusion criteria. The median age was 39 years with 77% being male and 41% sustaining a penetrating injury. Patients who received VP [VP (+)] were more likely to have a lower admission GCS (median 4.5 vs. 14.0, p <0.01) and less likely to have a penetrating injury (31% vs. 54%, p=0.02). The overall mortality was 49% and significantly higher in the VP (+) cohort (60% vs. 34%, AHR: 9.9, adjusted p=0.03). Mortality increased in a stepwise fashion with increasing number of VP utilized, starting at 34% for no VP, to 78% for 3 VP, and 100% for 5 or more. The majority of deaths in the VP (-) group (88%) occurred within one day from admission. For the VP (+) group, 57% of deaths occurred within one day, with the remaining 43% occurring at a later time.

CONCLUSION

In the era of massive transfusion protocols, vasopressors are commonly utilized in exsanguinating trauma patients and their use is associated with a higher mortality risk. Deaths in patients receiving vasopressors are more likely to occur later compared to those in patients who do not receive vasopressors. Further research to characterize the role of these agents in the resuscitation of trauma patients is required.

Early and sustained vasopressin infusion augments the hemodynamic efficacy of restrictive fluid resuscitation and improves survival in a liver laceration model of hemorrhagic shock

BACKGROUND

Current management of hemorrhagic shock favors restrictive fluid resuscitation before control of the bleeding source. We investigated the additional effects of early and sustained vasopressin infusion in a swine model of hemorrhagic shock produced by liver laceration.

METHODS

Forty male domestic pigs (32-40 kg) had a liver laceration inflicted with an X-shaped blade clamp, 32 received a second laceration at minute 7.5, and 24 received two additional lacerations at minute 15. Using a two-by-two factorial design, animals were randomized 1:1 to receive vasopressin infusion (0.04 U/kg per minute) or vehicle intraosseously from minute 7 until minute 240 and 1:1 to receive isotonic sodium chloride solution (12 mL/kg) intravenously at minute 30 or no fluids.

RESULTS

Kaplan-Meier curves showed greater survival after vasopressin with isotonic sodium chloride solution (8/10) compared to vasopressin without isotonic sodium chloride solution (4/10), vehicle with isotonic sodium chloride solution (3/10), or vehicle without isotonic sodium chloride solution (3/10), but the differences were not statistically significant (p = 0.095 by log-rank test). However, logistic regression showed vasopressin to elicit a statistically significant benefit on survival (p = 0.042). Vasopressin augmented mean aortic pressure between 10 and 20 mm Hg without intensifying the rate of bleeding from liver laceration, which was virtually identical to that of vehicle-treated animals (33.9 ± 5.1 and 33.8 ± 4.8 mL/kg). Vasopressin increased systemic vascular resistance and reduced transcapillary fluid extravasation, augmenting the volume of isotonic sodium chloride solution retained (6.5 ± 2.7 vs 2.4 ± 2.0 mL/kg by minute 60). The cardiac output and blood flow to the myocardium, liver, spleen, kidney, small bowel, and skeletal muscle at minute 120 and minute 180 were comparable or higher in the vasopressin group.

CONCLUSIONS

Early and sustained vasopressin infusion provided critical hemodynamic stability during hemorrhagic shock induced by liver laceration and increased the hemodynamic efficacy of restrictive fluid resuscitation without intensifying bleeding or compromising organ blood flow resulting in improved 240-minute survival.

Vasopressin Infusion with Small-Volume Fluid Resuscitation during Hemorrhagic Shock Promotes Hemodynamic Stability and Survival in Swine

Introduction

Current management of hemorrhagic shock (HS) in the battlefield and civilian settings favors small-volume fluid resuscitation before controlling the source of bleeding. We investigated in a swine model of HS the effects of vasopressin infusion along with small-volume fluid resuscitation; with erythropoietin (EPO) and HS severity as additional factors.

Methods

HS was induced in 24 male domestic pigs (36 to 41 kg) by blood withdrawal (BW) through a right atrial cannula modeling spontaneous bleeding by a mono-exponential decay function. The initial 12 pigs received no fluids; the last 12 pigs received normal saline (NS) half the BW volume. Pigs were randomized 2:1 to receive intraosseously vasopressin (0.04 U/kg·min^-1) or vehicle control from minute 7 to minute 210. Pigs assigned to vasopressin were further randomized 1:1 to receive EPO (1,200 U/kg) or vehicle control and 1:1 to have 65% or 75% BW of their blood volume. Shed blood was reinfused at 210 minutes and the pigs recovered from anesthesia.

Results

Survival at 72 hours was influenced by vasopressin and NS but not by EPO or % BW. Vasopressin with NS promoted the highest survival (8/8) followed by vasopressin without NS (3/8), NS without vasopressin (1/4), and neither treatment (0/4) with overall statistical significance (log-rank test, p = 0.009) and each subset different from vasopressin with NS by Holm-Sidak test. Vasopressin increased systemic vascular resistance whereas NS increased cardiac output.

Conclusion

Vasopressin infusion with small-volume fluid resuscitation during severe HS was highly effective enabling critical hemodynamic stabilization and improved 72 hour survival.

Comparison of normal saline, hypertonic saline albumin and terlipressin plus hypertonic saline albumin in an infant animal model of hypovolemic shock

Introduction

In series of cases and animal models suffering hemorrhagic shock, the use of vasopressors has shown potential benefits regarding hemodynamics and tissue perfusion. Terlipressin is an analogue of vasopressin with a longer half-life that can be administered by bolus injection. We have previously observed that hypertonic albumin improves resuscitation following controlled hemorrhage in piglets. The aim of the present study was to analyze whether the treatment with the combination of terlipressin and hypertonic albumin can produce better hemodynamic and tissular perfusion parameters than normal saline or hypertonic albumin alone at early stages of hemorrhagic shock in an infant animal model.

Methods

Experimental, randomized animal study including 39 2-to-3-month-old piglets. Thirty minutes after controlled 30 ml/kg bleed, pigs were randomized to receive either normal saline (NS) 30 ml/kg (n = 13), 5% albumin plus 3% hypertonic saline (AHS) 15 ml/kg (n = 13) or single bolus of terlipressin 15 μg/kg i.v. plus 5% albumin plus 3% hypertonic saline 15 ml/kg (TAHS) (n = 13) over 30 minutes. Global hemodynamic and tissular perfusion parameters were compared.

Results

After controlled bleed a significant decrease of blood pressure, cardiac index, central venous saturation, carotid and peripheral blood flow, brain saturation and an increase of heart rate, gastric PCO₂ and lactate was observed. After treatment no significant differences in most hemodynamic (cardiac index, mean arterial pressure) and perfusion parameters (lactate, gastric PCO₂, brain saturation, cutaneous blood flow) were observed between the three therapeutic groups. AHS and TAHS produced higher increase in stroke volume index and carotid blood flow than NS.

Conclusions

In this pediatric animal model of hypovolemic shock, albumin plus hypertonic saline with or without terlipressin achieved similar hemodynamics and perfusion parameters than twice the volume of NS. Addition of terlipressin did not produce better results than AHS.

Terlipressin with limited fluid resuscitation in a swine model of hemorrhage

BACKGROUND

Principles of damage control resuscitation include minimizing intravenous fluid (IVF) administration while correcting perfusion pressure as quickly as possible. Recent studies have identified a potential advantage of vasopressin over catecholamines in traumatic shock. Terlipressin (TP) is a vasopressin analogue used to reverse certain shock etiologies in some European countries.

STUDY OBJECTIVE

We evaluated three dosages of TP when combined with a limited colloid resuscitation strategy on mean arterial pressure (MAP) and lactatemia in a swine model of isolated hemorrhage.

METHODS

Sixty anesthetized swine underwent intubation and severe hemorrhage. Subjects were randomized to one of four resuscitation groups: 4 mL/kg Hextend(®) (Hospira Inc, Lake Forest, IL) only, 3.75 μg/kg TP + Hextend, 7.5 μg/kg TP + Hextend, or 15 μg/kg TP + Hextend. MAP and heart rate were recorded every 5 min. Baseline and serial lactate values at 30-min intervals were recorded and compared.

RESULTS

Subjects receiving 7.5 μg/kg TP had significantly higher MAPs at times t15 (p = 0.012), t20 (p = 0.004), t25 (p = 0.018), t30 (p = 0.032), t35 (p = 0.030), and t40 (p = 0.021). No statistically significant differences in lactate values between TP groups and controls were observed.

CONCLUSION

Subjects receiving 7.5 μg/kg of TP demonstrated improved MAP within 10 min of administration. When combined with minimal IVF resuscitation, TP doses between 3.75 and 15 μg/kg do not elevate lactate levels in hemorrhaged swine.

Hypothalamic-pituitary gland axis function and dysfunction in horses

Hypothalamic-pituitary (HP) dysfunction has been documented in a limited capacity in horses and foals associated with critical illness, stress, and pain. This article reviews species-specific details of anatomy, function, hormones, receptors, and testing of the HP axis in the horse. A discussion of critical care medicine relevant to HP dysfunction in the horse with some reference to current understanding in human medicine is made, focusing primarily on current and relevant literature. A brief mention of other conditions described in human and veterinary medicine is also provided for reference only, such as syndrome of inappropriate antidiuretic hormone secretion and other conditions.

Vasopressin for hemorrhagic shock management: revisiting the potential value in civilian and combat casualty care

The evolution of trauma care is driven by a synergistic relationship between civilian and military medical systems. Although the characteristics of civilian injuries differ from those encountered on the battlefield, the pathophysiologic process of dying is the same and dominated by exsanguination and central nervous trauma. As such, therapies that interfere with the physiologic ability to compensate hemorrhage may play a key role to buy time until hemostatic surgery can be initiated. From a variety of remedies with the potential to prolong the compensation phase or to reverse the decompensation phase of shock, arginine vasopressin (AVP) is one of the most promising and best-evaluated drugs. Animal studies and various case report series provide some evidence that AVP may improve blood pressure even when conventional therapies fail, thus preventing hypovolemic cardiac arrest and enabling resuscitation from fatal hemorrhage. On the basis of this civilian experience, it seems reasonable to consider AVP for hypotensive resuscitation in the austere, resource-constrained battlefield environment. However, the significance of AVP as a rescue medication for life-threatening hemorrhage has yet to be proven.

Arginine vasopressin: a promising rescue drug in the treatment of uncontrolled haemorrhagic shock

Haemorrhagic shock is one of the most frequent types of shock. If haemorrhage cannot be controlled and fluid resuscitation as well as catecholamines are insufficient to stabilize cardiovascular function, uncontrolled haemorrhagic shock occurs. Several approaches have been suggested as promising alternatives to volume resuscitation. The rationale for the use of arginine vasopressin (AVP) is the pharmacologic amplification of the neuroendocrine stress response. AVP-mediated vasoconstriction is the first physiologic step to haemostasis and shifts blood away from the bleeding site towards the heart, lungs and brain. Particularly, when uncontrolled haemorrhage is accompanied by traumatic brain injury this may help to reduce secondary neurological damage. Since AVP can prevent acute death only transiently, it must comprehensively be combined with rapid hospital admission, immediate control of haemorrhage followed by aggressive fluid resuscitation and blood transfusion. This review article summarizes current experimental and clinical evidence on the use of AVP in uncontrolled haemorrhagic shock.