1.5 Fluid balance during exercise Flashcards

ABCDEFGH

Airway

Breathing

Circulation

Disability (Mental Status)

Environment (Rectal Temperature)

Fluid status including change in body weight

Blood Glucose and Sodium

History including site of collapse

• Cardiac arrest

• Hypoglycaemia

• Anaphylaxis

• Other medical conditions

• Trauma/Orthopaedic injuries

• Heatstroke

• Hypothermia

• Exercise-associated hyponatraemia

• Exercise-associated postural hypotension

Exercise-associated postural hypotension

“The inability to stand or walk unaided as the result of light headedness, faintness, dizziness or syncope”

• Postural hypotension related to cessation of activity

• Place runner supine and head-down
• Oral fluids

Hyperthermia is high rectal temperature (usually >40oC) in an

athlete who, other than feeling exhausted, is usually well.

• Symptoms or signs of organ dysfunction
• And a core body temperature >40oC

is a normal physiological response to intense exercise or physical activity

Endogenous heat production: muscle activity and metabolism

+

Exogenous heat absorbtion: environmental

In low environmental temperatures, heat is lost through:

Convection + Radiation + (Small contribution from conduction)

Increasing environmental temperatures:

sweating = effective heat loss through evaporation

In Humid conditions:

evaporation is reduced > ineffective cooling

Athlete is unable to lose heat > begins to overheat

Cerebral hyperthermia:

• hypothalamic failure and loss of thermoregulatory control
• Rhabdomyolysis
• renal failure
• hyperkalaemia

Intense inflammatory response:

Inflammatory cytokines trigger a systemic inflammatory response (SIRS):

• tissue hypoxia
• metabolic acidosis
• Acute kidney injury
• Acute liver failure
• Acute hypotensive shock
• Multi-system organ failure

• EHS
• Mortality and prognosis is largely dependent on early recognition and prompt management

• Cold water immersion is the most effective cooling modality
• Shade, strip, spray and fan (S3F) is recommended where CWI is contraindicated or not possible

Pathophysiological continuum from mild symptoms (fatigue, headache) to collapse, coma and death because of a rise in core temperature

a physiological response to inadequate acclimatisation

a physiological response to inadequate training

[Na+] <135 mmol/L1

dilutional hyponatraemia occurring during or <24hr after exercise

Relative hyponatraemia in the vascular compartment causes an osmotic fluid shift into adjacent tissues

Cerebral edema

• agitation
• LOC
• confusion
• Drowsiness
• stupor

GI symotoms

• nausea
• vomiting
• diarrhea

Other

• Headach

Excessive fluid intake

• Excessive consumption irrespective of fluid type

Reduced fluid output (Altered renal function)

• Exercise ( RBF and GFR fall by 40% after exercise)
• ADH (0.5 pg/mL) in 43 % of cases
• NSAIDs ( Indomethacin, and celecoxib significantly reduced free water clearance)

• Females
• slower runers
• >4hrs exercise time

● Observe closely

● Salty snacks or salty broth

● No oral fluids until onset of urination

● No iv fluids

● Oxygen

● 100ml bolus iv 3% Hypertonic Saline

● May require hospital admission

● Check and treat [Na+] before imaging

● Use 2.7% or 3% Hypertonic Saline

● AVOID Normal Saline

1. Drink according to thirst: ad libitum

2. Avoid excessive drinking during and after exercise

3. Sports drinks do not prevent EAH

4. Sodium supplementation does not prevent EAH

• age
• sex
• FFM
• Body weight
• PAL
• athletes
• HDI
• Air temprature
• Humidity
• Altitiude

1. We need to drink 2 liters of water a day

2. Sports drinks prevent EAH

3. Thirst is imperfect

• The energy cost of running a marathon for an average

70 kg male is roughly 12,000 kJ (4.18 kJ·kg−1·min−1).

• Estimates of carbohydrate oxidation indicate that an

elite male runner would utilise 400 g of glycogen

• given the accepted value of 3 g of water per gram of

oxidised glycogen, this would result in a 1200 mL

endogenous water release