DEHYDRATIONDEHYDRATION

Prof. Sultan Ayoub MeoMBBS, M.Phil, Ph.D (Pak), M Med Ed (Dundee), FRCP (London),

FRCP (Dublin), FRCP (Glasgow), FRCP (Edinburgh)Professor and Consultant, Department of Physiology and University

Diabetes Centre, College of Medicine, King Saud University, Riyadh, KSA

Dehydration occurs when body does not have as much water and fluids as it needs. Dehydration is classified as mild, moderate, or severe

DEHYDRATIONDEHYDRATION

In average young adult male:

Body Composition

Body composition % of body weight

Protein, & related substances 18%

Fat 15%

Mineral 7%

Water 60%

Body Fluids

Fluid Compartments 60% of body weight

Extracellular Extracellular fluidfluid

(( 1/3)1/3) 33% of TBW33% of TBW

20% of body wt

Intracellular Intracellular fluidfluid

(( 2/3)2/3) 67% of TBW67% of TBW

40% of body wt

Interstitial Interstitial fluidfluid

75% of ECF75% of ECF 15% of body

wt

PlasmaPlasma 25% of ECF25% of ECF 5% of body

wt

Transcellular Transcellular fluidfluidCSFCSF

IntraoculaIntraocularr

PleuralPleuralPeritoneaPeritonea

llPericardiaPericardia

llSynovialSynovialDigestive Digestive secretionsecretion

ss

Body Fluids: Intake and Output

Factors affecting body fluids Water intake & output Age: - infant: 73% - elderly: 45% Gender: - adult male: 60% - adult female: 40-50% Obesity Climate Habits Level of physical activity

Dehydration: Causes

Not drinking enough water: Sore throat, mouth sores, difficulty swallowing, and/or a decreased thirst sensation (especially in older adults)Illness: Nausea, vomiting, diarrhea, fever, pain, burnOverheated indoor / outdoor air: Mobility: Inability to get water: Old ageExcessive urine output: Uncontrolled diabetes, diureticsMedications: Laxatives, sedatives/sleeping pills/anxiety medicationsExcessive exercise, heat, humidity

Dehydration: Causes

Control of body fluids

Thirst Sweating Renal control (aldosterone) Neuronal (osmoreceptors, baroreceptors)

Control of body fluids

Control of body fluids: ADH Role

Control of body fluids

Control of body fluids

Dehydration Loss of water from the body, e.g. vomiting, diarrhea, sweating, & polyuria. Leads to in both ECF & ICF volumes. osmolarity in both ECF & ICF. General signs: - Dry tongue - loss of skin elasticity - soft eyeballs (due to lowering of intraocular tension) - blood pressure (if 4-6L loss) - Hb, & Hct (packed cell volume) Treated w fluid replacement (orally, or IV).

Dehydration

Dehydration: Clinical Features

Dehydration: Clinical Features

Dehydration: Clinical Features

Dehydration: Clinical Features

Dehydration: Adverse Effects

Dehydration: Adverse Effects

Dehydration: Adverse Effects

Dehydration:

Dehydration: Assessment and Management

Dehydration: Assessment and Management

Oral rehydration salts: ORS. A solution of glucose -based salt solution used in oral rehydration therapy. WHO and UNICEF recommend a single formulation of glucose-based ORS to treat or prevent dehydration

ORS solution contains 75 mEq/l of sodium and 75 mmol/l of glucose, and have a total osmolarity of 245 mOsm/l.