Small Animal Emergency and Critical Care Medicine: Self-Assessment Color Review, Second Edition, Q&A 03

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Student tip: This case is an excellent overview of the pharmacological intervention required when BP drops.

You have provided analgesics and fluid resuscitation for hypovolemic shock for a dog with pyometra. Isotonic balanced crystalloids and HES were infused using large volume resuscitation techniques to high end end-points. Post-infusion parameters are: CVP = 10 cmH2O; HR = 150 bpm; CRT = 2 sec; MM pale pink; weak femoral pulses; Doppler SABP = 78 mmHg; blood lactate = 3.5 mmol/l (31.5 mg/dl) (5.0 mmol/l [45 mg/dl] before fluids).

Question	Answer		Article
List at least five parameters or conditions that can contribute to non-responsive shock.	Inadequate volume administered; pain; ongoing fluid loss; third-body fluid spacing; hypoglycemia; electrolyte disorders; acid–base disorders; cardiac arrhythmias; myocardial depression or failure; organ ischemia; anemia; brainstem pathology; excessive vasodilation or vasoconstriction; hypoxemia; hypercarbia; cardiac tamponade; decreased venous return.		Link to Article
Arterial blood gas, glucose, electrolyte panel, and hematocrit are normal. What step(s) are taken next to improve perfusion?	The CVP of 10 cmH2O implies adequate central volume (unless right heart failure or pericardial effusion). A fluid challenge with 5–10 ml/kg of HES can be done to detect the effect on CVP and SABP with additional fluids. Inadequate response to fluid challenge is indication for pharmacologic management of BP.		Link to Article
Which of the following drugs might be used to treat non-responsive shock? How do they work? Dobutamine, dopamine, norepinephrine, Oxyglobin®, esmolol, diltiazem.	Dobutamine is a direct stimulant of beta1 receptors of the sympathetic nervous system and would be indicated for depressed myocardial contractility. Dopamine is an inotropic and vasopressor catecholamine and is often a first-line agent for pharmacologic BP support. Norepinephrine increases BP by increasing vascular tone through alpha adrenergic receptor activation. Oxyglobin® is polymerized bovine hemoglobin that acts as a colloid, carries oxygen, and has mild vasopressor activity. Esmolol is a selective beta1 receptor blocker that is only indicated if a severe tachycardia is responsible for the poor cardiac output. Diltiazem injectable is a calcium channel blocker only indicated if a severe tachycardia is responsible for the poor cardiac output.		Link to Article

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