Thirst-guided Subject-controlled Rehydration in Healthy Volunteers

Water is largest single component to the human body and is requisite for numerous essential metabolic processes. Dehydration refers to deficient body water content and is prevalent in healthcare. It has been repeatedly shown that dehydration is associated with increased mortality and morbidity. Despite its prevalence and deleterious sequelae, there is substantial deficiency in the knowledge, assessment and management of this pathological state: there is no internationally-recognised definition, clinical signs can be subtle and unreliable, and there is no objective marker with everyday clinical utility. As a consequence, diagnosis of dehydration and prompt rehydration strategies are often poorly delivered in healthcare environments.

Thirst plays an integral part in body water homeostasis. Plasma osmolality will increase with uncompensated water loss and is considered the most reliable surrogate objective marker of dehydration. Increased osmolality is sensed by hypothalamic osmoreceptors stimulating thirst and pituitary secretion of antidiuretic hormone (ADH). Thirst has been shown to be sensitive to small changes in plasma osmolality and shows little intra-individual variation. In view of this, it is rational to propose tendering control of intravenous rehydration to patients, enabling them to use the finely-honed intrinsic thirst mechanism to guide their own fluid therapy. A recent pilot study demonstrated that healthy subjects, when allowed to regulate their own intravenous fluid therapy in response to thirst intensity, rehydrated themselves more efficiently than subjects receiving a guideline-based, clinician-delivered fluid regimen. What is unclear is the extent of the reliability of thirst in guiding intravenous fluid rehydration therapy.

The investigators propose a double-blinded, repeated measures study in which healthy volunteers are dehydrated using exercise-heat stress in a climatic chamber. Once dehydrated by 3-5% of their body weight, subjects will receive intravenous fluid rehydration which they can demand in response to their sensation of thirst. In one arm of the study they will receive low volume fluid bolus on demand, and in the other arm they will receive a higher volume fluid bolus. Thirst scores and surrogate markers of dehydration will be measured throughout this process. The investigators can then assess whether the demand for additional fluid in response to thirst reduces in frequency in proportion to the degree of correction of fluid deficit.

Study Overview

• Status: Unknown
• Conditions: Dehydration Hypertonic
• Intervention / Treatment: Device: Patient controlled fluid device administering low volume thirst guided fluid bolus; Device: Patient controlled fluid device administering high volume thirst guided fluid bolus

• Study Type: Interventional
• Enrollment (Anticipated): 16
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Portsmouth, United Kingdom, PO1 2UP
    • Department of Sport and Exercise Science

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Healthy physically active male volunteers aged 18-65 years.
• Participants must be normotensive (systolic pressure between 90 and 150 mmHg, diastolic pressure between 60 and 90 mmHg).
• Participants greater than 29 years of age will be required to have a 12 lead ECG evaluated by an appropriate IMO prior to participating.

Exclusion Criteria:

• Known cardiovascular disease
• Known renal disease
• Known hepatic disease
• Taking medications which might affect sense of thirst or salt/water handling
• History of heat intolerance

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Lower Volume fluid bolus arm; The 'lower volume' (LV) fluid bolus arm will receive a continuous background infusion of 4% dextrose in 0.18% NaCl at 50ml/hr for the entire 4 hour rehydration period. Subjects will be given a hand-held trigger, which when pressed will deliver an additional volume of fluid from the infusion pump; this will be administered over a 10-minute period (thus allowing a maximum of 6 boluses per hour). In the LV arm, the trigger will deliver 50mls over 10 mins at a rate of 300ml h-1. A green LED will signal to the patient that no additional infusion is running, and that pressing the trigger will activate delivery of another bolus. The volume and lockout periods for the boluses may vary but will remain within the maximum fluid administration of 1200mls per hour.	Device: Patient controlled fluid device administering low volume thirst guided fluid bolus; The administration of a 50ml fluid bolus in response to subjective thirst. Participant activates trigger in response to thirst which activates fluid pump to deliver 50ml IV fluid bolus of 4% dextrose & 0.18% sodium chloride
Experimental: Higher Volume fluid bolus arm; The 'higher volume' (HV) fluid bolus arm will receive a continuous background infusion of 4% dextrose in 0.18% NaCl at 50ml/hr for the entire 4 hour rehydration period. Subjects will be given a hand-held trigger, which when pressed will deliver an additional volume of fluid from the infusion pump; this will be administered over a 10-minute period (thus allowing a maximum of 6 boluses per hour). In the HV arm, the trigger will deliver 200mls over 10 mins at a rate of 1200ml h-1. A green LED will signal to the patient that no additional infusion is running, and that pressing the trigger will activate delivery of another bolus. The volume and lockout periods for the boluses may vary but will remain within the maximum fluid administration of 1200mls per hour.	Device: Patient controlled fluid device administering high volume thirst guided fluid bolus; The administration of a 200ml fluid bolus in response to subjective thirst. Participant activates trigger in response to thirst which activates fluid pump to deliver 50ml IV fluid bolus of 4% dextrose & 0.18% sodium chloride

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total Volume	The primary outcome measure is the total volume of fluid administered during the infusion	This will be measured over the 4 hour rehydration infusion

Collaborators and Investigators

• Sponsor: University College, London
• Collaborators: University of Portsmouth; University of Wollongong

Publications and helpful links

General Publications

• Lacey J, Corbett J, Shepherd A, Dubois A, Hughes F, White D, Tipton M, Mythen M, Montgomery H. Thirst-guided participant-controlled intravenous fluid rehydration: a single blind, randomised crossover study. Br J Anaesth. 2020 Jan 31:S0007-0912(19)30974-2. doi: 10.1016/j.bja.2019.12.008. Online ahead of print.

Study record dates

Study Major Dates

• Study Start (Actual): July 17, 2018
• Primary Completion (Anticipated): January 1, 2020
• Study Completion (Anticipated): January 1, 2020

Study Registration Dates

• First Submitted: July 6, 2018
• First Submitted That Met QC Criteria: April 26, 2019
• First Posted (Actual): May 1, 2019

Study Record Updates

• Last Update Posted (Actual): May 15, 2019
• Last Update Submitted That Met QC Criteria: May 14, 2019
• Last Verified: July 1, 2018

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pathologic Processes; Metabolic Diseases; Water-Electrolyte Imbalance; Dehydration
• Other Study ID Numbers: SFEC 2018-053A

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: No data other than final aggregate results will be available to other researchers

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No