4 Horse Anesthesia: Issues and Logistics

Why are horses considered obligate nasal breathers, a crucial factor in equine anesthesia management?

During equine anesthesia, 'blind intubation' is a common technique. What primary anatomical feature necessitates this approach?

Myopathy is a significant peri-anesthetic risk in horses. Which of the following is the MOST critical factor in mitigating anesthetic myopathy?

Neuropraxia in anesthetized horses is often associated with positioning and recumbency. What is the underlying pathophysiological mechanism of anesthetic neuropraxia?

Horses are prone to hypoventilation under anesthesia. What is the MOST significant physiological consequence of hypoventilation in an anesthetized horse?

Ventilation-perfusion (V/Q) mismatch is a common concern in equine anesthesia. Which of the following best describes the primary cause of increased V/Q mismatch in recumbent anesthetized horses?

Consider the alveolar gas equation: $PAO_2 = FiO_2(P_{atm} - P_{H_2O}) - \frac{PaCO_2}{0.8}$. If, at sea level ($P_{atm} = 760 mmHg$), the $P_{H_2O}$ is 47 mmHg, $FiO_2$ is 0.21, and $PaCO_2$ is 60 mmHg in an anesthetized horse, what is the approximate $PAO_2$?

In equine anesthesia, a large Alveolar-arterial oxygen difference (A-a gradient) is often observed even with high $FiO_2$. What is the PRIMARY physiological mechanism contributing to this large A-a gradient?

Despite achieving a high $PAO_2$ by increasing $FiO_2$ to 1.0 in a severely hypoxemic anesthetized horse, the $PaO_2$ remains unexpectedly low. Which of the following best explains why simply increasing $FiO_2$ might be INSUFFICIENT to correct severe hypoxemia in this scenario?

Positive End-Expiratory Pressure (PEEP) is sometimes used in equine anesthesia. What is the PRIMARY intended benefit of applying PEEP in anesthetized horses?

Hyperkalemic Periodic Paralysis (HYPP) is a breed-specific issue in horses, particularly in Quarter Horses and related breeds. What is the underlying genetic and physiological mechanism of HYPP?

Malignant hyperthermia (MH) is a potentially fatal pharmacogenetic disorder that can occur in anesthetized horses. What is the MOST critical initial step in managing a horse exhibiting signs of MH during anesthesia?

Acepromazine is a commonly used premedicant in equine anesthesia. What is the PRIMARY pharmacological action of acepromazine that makes it beneficial in this context?

Alpha-2 adrenergic agonists, such as xylazine or detomidine, are frequently used in equine anesthesia protocols. What is the MAIN physiological effect of these drugs that contributes to their sedative and analgesic properties?

Ketamine is a dissociative anesthetic commonly used for induction in equine anesthesia. What is the primary mechanism of action of ketamine at the neuronal level?

Propofol is an ultra-short-acting intravenous anesthetic agent sometimes used in equine anesthesia induction. What is the primary molecular target of propofol that mediates its anesthetic effects?

Inhalant anesthetics such as isoflurane and sevoflurane are widely used for maintenance of equine anesthesia. What is the generally accepted primary mechanism by which inhalant anesthetics induce general anesthesia?

Large animal anesthetic circuits, typically 30-50 liters in volume, are used in equine anesthesia. What is the PRIMARY reason for needing such large circuit volumes?

The 'time constant' of an anesthetic circuit is approximately 3-5 minutes for large animal circuits. What does 'time constant' refer to in the context of anesthetic circuits?

During equine anesthesia monitoring, 'nystagmus' is mentioned as a sign of being 'too light'. What type of nystagmus is typically indicative of inadequate anesthetic depth in horses?

Ephedrine and dobutamine are mentioned for blood pressure management during equine anesthesia. What is the primary pharmacological difference in their mechanisms of action in raising blood pressure?

During equine anesthesia, if low compliance is detected in a mechanically ventilated horse, what is the MOST likely consequence on the ventilator settings and pressures?

Equine anesthetic recovery is described as the 'most critical period'. What is the PRIMARY reason recovery poses a higher risk compared to other phases of equine anesthesia?

Mortality rates in equine anesthesia are significantly higher than in small animal anesthesia. Based on the provided data, what is the approximate mortality rate for horses under anesthesia?

Catastrophic fractures are listed as a cause of mortality during equine anesthetic recovery. What is the MOST common mechanism leading to these fractures during recovery?

'Free recovery' is a philosophy for equine anesthetic recovery. What is a key characteristic of 'free recovery' in horses?

'Rope-pulley assisted recovery' is another approach in equine anesthesia. What is the PRIMARY rationale for using rope-pulley systems during equine recovery?

'Pool recovery' is mentioned as a recovery method for horses. What is the hypothesized primary advantage of using a pool for equine anesthetic recovery?

The importance of sedation in equine anesthetic recovery is emphasized. What is the MAIN goal of using sedation during the recovery phase?

Which of the following is considered a 'breed-specific issue' that can significantly impact equine anesthesia management?

Draft breeds are mentioned in the context of breed issues in equine anesthesia. What is a common anesthetic consideration specific to draft horses?

Upper airway obstruction is listed as a cause of mortality in equine anesthetic recovery. What is the MOST common cause of upper airway obstruction in recovering horses?

Compared to smaller animal anesthesia, equine anesthesia necessitates greater attention to 'logistics and personnel'. Which of the following BEST exemplifies a logistical challenge unique to equine, versus canine, anesthesia?

During equine anesthesia induction, 'chemical and/or physical restraint' is often required. In what scenario would physical restraint be considered MOST necessary, even when chemical restraint is planned?