Fluid Management in the Hypotensive Patient. Steven Roberts Cardiac Course 6 May 2008. Content:. 1. Definitions of blood pressure, hypotension and fluid management 2. The body’s natural regulation of blood pressure and fluid content - and what can go wrong
Cardiac Course 6 May 2008
1. Definitions of blood pressure, hypotension and fluid management
2. The body’s natural regulation of blood pressure and fluid content - and what can go wrong
3. Fluid management in our patients
4. Nursing priorities
The force per unit area exerted on the walls of
the blood vessels, by the blood contained
Normal BP: 100/60 to 140/90 mmHg
A systolic blood pressure of less than 100mmHg.
Reasons for hypotension:
Fluid management (osmoregulation):
An important part of homeostasis that attempts
to maintain fluid volume and electrolyte
concentrations within limits that allow
necessary physiological processes to take
Pressure difference makes blood flow.
Flow is necessary for perfusion of the tissues
(particularly the kidneys and the brain).
Hypotension - not enough flow for perfusion
Hypertension - too much pressure, possibility of damage
A ‘weighted average’ pressure that allows
estimation of effective perfusion of the tissues.
eg. MAP 65mmHg for renal perfusion
MAP = 1/3 systolic + 2/3 diastolic or
MAP = (systolic + 2 x diastolic)/3
Systolic 120 110 100 90 80 70 65
Diastolic 37 42 47 53 57 62 65
MAP 65 65 65 65 65 65 65
Neural: stretch, vagal response, slower HR and less tone in blood vessels
Chemical: less oxygen detected, vasoconstriction, rise in BP facilitates venous return and pulmonary perfusion
Renal: fall in BP, release of renin - angiotensin (vasoconstrictor) - aldosterone (Na+ reabsorption)
(Age, illness, drugs, other body systems, all may
affect effective blood pressure regulation)
Water is 60% of the body mass of an average man.
2/3 is ICF in cytosol in all body cells.
1/3 is ECF outside cells - interstitial and circulation.
Total: 40 litres
ICF: 28 litres
ECF: 12 litres (plasma: 2.5 litres, interstitial fluid: 9.5 litres)
Homeostasis of water and electrolytes in the fluid
compartments is essential for life and health.
a) Input and Output
Water and other small molecules can pass
freely across cell and capillary membranes.
They may do this by:
a) Fluid volume deficit: (not dehydration)
b) Fluid volume excess: (oedema)
a) Hyperosmolar imbalance: (dehydration)
b) Hypo-osmolar imbalance: (water excess)
b) Nursing observations