Diabetes Insipidus (DI) is characterized by the production of copious amounts of dilute urine. Awake patients with intact hypothalamic thirst mechanisms will be thirsty and may be able to compensate for acute or chronic DI. However, anesthetized or critically ill patients cannot and must receive fluid replacement and hormonal therapy (in the case of central DI).
DI can be due to central (neurogenic) or nephrogenic causes. Nephrogenic DI is most commonly drug induced. Central DI is due to vasopressin deficiency in the setting of hypothalamic pituitary malfunction/injury.
Anesthesiologists usually encounter central DI in the operating room- most commonly in the setting of craniotomy with hypothalamic-pituitary injury or in brain dead patients coming to the operating room for organ harvest. High urine output, low urine specific gravity, negative fluid balance, and rising serum sodium herald the diagnosis of DI.
Central DI is managed in the operating room with intravenous vasopressin titrated to control urine output. Fluid balance, intravascular fluid volume, and serum sodium should be monitored closely. Subcutaneous or nasal desmopressin (ddAVP) can be used but is generally suboptimal for use in the operating room.
- Nair-Collins M, Northrup J, Olcese J. Hypothalamic-Pituitary Function in Brain Death: A Review. J Intensive Care Med. 2014 Mar 31. [Epub ahead of print] PubMed PMID: 24692211.