Emergency Medicine/Critical Care: free VTNE practice questions

Sepsis is the systemic inflammatory response to an infection, and the form of shock it produces is distributive shock. In distributive shock the vascular compartment itself expands. Vessel tone is lost - through a decrease in sympathetic control of vasomotor tone, through the release of vasodilatory mediators, or both - and a normal volume of blood is then insufficient to fill the dilated compartment. Blood is displaced away from the heart and the central circulation, preload is diminished, and stroke volume and cardiac output fall as a result. In sepsis specifically, various mediators are released that affect capillary permeability and the distribution of blood flow to the tissues and organs; prostaglandin is one example of a mediator that causes vasodilation. Sepsis, anaphylaxis and neurogenic states all reach shock by this route.

Option D is the tempting one, because the end result - poor preload, poor cardiac output - looks identical at the cage side. The distinction is that in distributive shock there is no total decrease in blood volume; the blood is in the wrong place rather than gone, which is why the category exists as something separate from hypovolemic shock.

Options A and B describe real mechanisms of poor cardiac output, but both are forms of cardiac dysfunction rather than what sepsis does. Reduced contractility means the pump is weak, and a tachyarrhythmia lowers end-diastolic volume by denying the heart enough time to fill - each will drop stroke volume and cardiac output, but neither depends on the vascular compartment having enlarged.

The RECOVER Initiative, the first evidence-based guidelines for veterinary CPR, identifies properly administered chest compressions as one of the most important features of successful resuscitation, and names posture, technique, and the proper compression point as the things that matter. For cats and small dogs weighing less than about 5 to 7 kg, the patient is placed in lateral recumbency, the caregiver's hand encircles the ventral chest, and compressions are delivered directly over the heart. The caregiver should be careful to use the whole hand rather than just the fingertips. A two-handed technique may be used, but with caution, because the patient is small and the chest wall is generally very compliant, and it is easy to overdo compressions on a patient this size.

Option B is the technique used in larger dogs, where positioning and technique depend on the animal's size and conformation and a two-handed method with interlocked hands and straight arms is used; it is not what a 4 kg cat calls for.

Option C is the specific error the guidelines warn against - the compliant chest wall is the reason to be cautious with a two-handed technique, not a reason to abandon the whole hand.

Option D is the most damaging choice, because once arrest is suspected the first responders start chest compressions immediately: delaying compressions is worse than performing them on an animal that turns out not to be in arrest. The airway is secured with an endotracheal tube as additional staff arrive, and oxygen is generally indicated at that point, but CPR can be performed successfully without oxygen.