Sudden Bradycardia and Hypotension in Neurosurgery: Trigeminocardiac Reflex (TCR) and More

Optimal Temperature of Irrigation Fluid for Hemostasis in Neurosurgery: A Narrative Literature Review

BACKGROUND

 Hemostasis in neurosurgery is crucial to patient and surgery outcomes, with many techniques developed for this. One area that is not appropriately characterized despite continuous anecdotal evidence the temperature of the irrigation fluid (IF) used and its effects on stemming hemorrhages. Given the ubiquitous use of IF in neurosurgery for clearing blood from the surgical field, it is important to explore its role as a hemostat and whether or not the temperature of the IF influences its hemostatic capacity. This review explored the literature for an optimal IF temperature for hemostasis in neurosurgery.

METHODS

 Database searches were conducted using MEDLINE, Scopus, Web of Science, and CINAHL, with citation chaining occurring where applicable. Standard terms around neurosurgery, hemostasis, and irrigation were used.

RESULTS

 Seven articles were identified. No optimal temperature for hemostasis could be confidently synthesized from the literature owing to lack of primary investigation on the subject. After collating available information into common themes, it is suggested that that temperatures >38°C are preferred.

CONCLUSION

 The literature in this area is limited. Despite a lack of applicable systematic investigation on the topic, by exploring the physiology of hemostasis and IF, best practice guidelines for IF, and the literature on the role of the temperature of IF in other surgical specialties, it is suggested that a temperature in the range of 38 to 40°C would be most applicable to a value optimal for neurosurgery.

Anaesthetic management in a cat undergoing emergency craniotomy for meningioma excision

Case summary

A 15-year-old female spayed domestic shorthair cat underwent an emergency craniotomy to remove an intracranial meningioma causing marked midline shift, caudal transtentorial and foramen magnum herniation. Because intracranial structures are enclosed in the cranium, any volume-occupying lesions might raise intracranial pressure (ICP), compromising cerebral perfusion.

Relevance and novel information

This case report discusses the anaesthetic management of a cat that presented with marked bradycardia and concomitant hypotension. Cushing's reflex (CR) is a well-recognised cardiovascular reflex following sudden ICP increase, and it features an irregular breathing pattern and increased arterial blood pressure with reflex bradycardia. However, CR is reported to have a low sensitivity for the detection of raised ICP in humans with traumatic brain injury. In a previous study reporting seven cats undergoing surgical removal of intracranial meningioma, ICP was measured in four cases and, in these patients, CR was not observed during surgery. Because bradycardia was not secondary to hypertension, in this case, it might have been the result of direct compression of the nucleus of the vagus nerve. Based on the literature search, there is paucity of reports of cardiovascular changes in cats with increased ICP and their perianaesthetic management.