To Relieve the Patient's Thirst, Refresh the Mouth First: A Pilot Study Using Mini Mint Ice Cubes in Severely Dehydrated Patients

Thirst refers to the urge to drink and it is consistently reported as one of the top five stressful symptoms by critically ill patients. 1 Kalfon P. Baumstarck K. Estagnasie P. et al. A tailored multicomponent program to reduce discomfort in critically ill patients: a cluster randomized controlled trial. Intensive Care Med. 2017; 43: 1829-1840 Crossref PubMed Scopus (14) Google Scholar It can also become a real torment for terminally ill patients 2 Morita T. Tei Y. Tsunoda J. Inoue S. Chihara S. Determinants of the sensation of thirst in terminally ill cancer patients. Support Care Cancer. 2001; 9: 177-186 Crossref PubMed Scopus (73) Google Scholar or severely dehydrated individuals. 3 Engell D.B. Maller O. Sawka M.N. Francesconi R.N. Drolet L. Young A.J. Thirst and fluid intake following graded hypohydration levels in humans. Physiol Behav. 1987; 40: 229-236 Crossref PubMed Scopus (138) Google Scholar However, thirst is often overlooked, poorly understood, and underrecognized in the hospital. 4 So H.M. Chan D.S. Perception of stressors by patients and nurses of critical care units in Hong Kong. Int J Nurs Stud. 2004; 41: 77-84 Crossref PubMed Scopus (51) Google Scholar For a long time, it was thought to be closely related to changes in the blood volume or plasma osmolarity and to the regulation of blood sodium concentration (Na+). 5 Kumar S. Berl T. Sodium. Lancet. 1998; 352: 220-228 Abstract Full Text Full Text PDF PubMed Scopus (288) Google Scholar ,6 Baylis P.H. Thompson C.J. Osmoregulation of vasopressin secretion and thirst in health and disease. Clin Endocrinol. 1988; 29: 549-576 Crossref PubMed Scopus (103) Google Scholar Rehydration usually aims at normalizing biological targets like Na+ or plasma osmolarity, and the preferred routes for rehydration in the hospital are intravenous fluid administration and nasogastric tube feeding. 7 Rosner M.H. Ronco C. Dysnatremias in the intensive care unit. Contrib Nephrol. 2010; 165: 292-298 Crossref PubMed Scopus (19) Google Scholar For many reasons, oral intake is not advised in the critically ill patient and the mouth is commonly not taken into account when severe dehydration occurs. Water, cold, and mint can independently modulate the sensation of thirst by their effects on thermoreceptors and osmoreceptors in the mouth. 8 Eccles R. Role of cold receptors and menthol in thirst, the drive to breathe and arousal. Appetite. 2000; 34: 29-35 Crossref PubMed Scopus (79) Google Scholar A recent animal study supported the critical role of thirst-promoting neurons of the subfornical organ that both receive input from the mouth and integrate blood composition to anticipate the variations in plasma homeostasis. 9 Zimmerman C.A. Lin Y.C. Leib D.E. et al. Thirst neurons anticipate the homeostatic consequences of eating and drinking. Nature. 2016; 537: 680-684 Crossref PubMed Scopus (162) Google Scholar In accordance with these physiological observations and recent animal findings, the aims of this physiological study were 1) to investigate whether thirst can be efficiently relieved by the simple application of mini mint ice cubes in the mouth of critically ill profoundly dehydrated subjects suffering from craving thirst and significant hypernatremia; 2) to give a refreshing insight into the understanding of the relationship between thirst, osmolarity, Na+, water intake, and the route used for rehydration in severely dehydrated subjects.