Thirst-guided Subject-controlled Rehydration in Healthy Volunteers

Summary

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.

Conditions

• Dehydration Hypertonic

Interventions

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

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

Sponsors & Collaborators

• University of Portsmouth

  collaborator OTHER

• University of Wollongong

  collaborator OTHER

• University College, London

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

65 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2018-07-17

Primary Completion

2020-01-01

Completion

2020-01-01

Countries

• United Kingdom

Study Locations