Limited Intravenous Access: Role of Im Vasopressin in Vasodilatory Shock

Abstract

Introduction:Vasopressin is an antidiuretic hormone analog that has become an important drug in the treatment of vasodilatory shock through its vasoconstrictive and water retention properties to maintain blood pressure. We present two cases of vasodilatory shock where intravenous access was limited and intramuscular (IM) vasopressin was used for management.CASE PRESENTATION: Patient 1: An 85 year old female with a medical history of hypertension and colon cancer presented with septic shock. She received dopamine via midline on the upper left arm to maintain blood pressure, with the patient's healthcare proxy refusing a central line. Multiple attempts to obtain venous access for a blood transfusion were unsuccessful. The dopamine drip could not be held due to severe hypotension. The decision was made to administer IM vasopressin (10 Units) to maintain blood pressure while stopping dopamine during the blood transfusion. The transfusion was completed over two hours and the blood pressure improved from 76/39 -123/63. Patient 2: A 63 year old male with a medical history of smoking and peripheral vascular disease was admitted for tachycardia and hypoxia. He had necrotizing pneumonia and was in septic shock. He continued to be volume unresponsive despite intravenous fluid resuscitation. He was placed on a dopamine drip to maintain blood pressure and became tachycardic and remained in shock. Bedside ultrasound showed signs of volume overload. Twenty units of intramuscular vasopressin was given and blood pressure improved within 15 minutes and was maintained between 120/ 76-105/69 for 1.5 hours.DISCUSSION: Very frequently we encounter difficulties obtaining intravenous access while resuscitating a patient. Such situations pose an immense challenge in managing shock. Vasopressin is unique in its ability to be utilized intramuscularly. [1] Utilizing medications intramuscularly for urgent situations has a significant impact on management when there is limited, or lack of, intravenous access for hemodynamically unstable patients. The onset of action for vasopressin is approximately two hours, however our patient showed response within 15 minutes, demonstrating its potential.[1] After the initial onset of shock, endogenous stores of antidiuretic hormone are consumed and the vasodilatory mechanisms of shock may propagate.[3] Vasopressin itself may reverse some of the vasodilatory changes induced in shock, and in combination with other pressors may prove to be of greater benefit than that of pressors alone. [2] CONCLUSIONS: In the setting of shock with limited intravenous access, intramuscular vasopressin may be an effective option for initial stabilization until IV access is obtained.