PN 4003 EXAM STUDY SET 2024-2025
Arterial Blood Gasses
pH: 7.35 - 7.45
PaCO235
HCO3
- 45 mmHg 22-26 mEq/L
Sensible losses
Urination
Defecation
Wound drainage
Insensible losses
Evaporation from skin
respiratory loss through lungs
isotonic solution
No fluid shift because solutions are equally concentrated
* Normal saline solution (0.9% NaCl)
Hypotonic solution
Lower solute concentration
* Fluid shifts from hypotonic solution into the more concentrated solution to create
a balance (cells swell)
* Half-normal saline solution (0.45% NaCl)
Hypertonic solution
,Higher solute concentration
* Fluid is drawn into the hypertonic solution to create a balance (cells shrink)
* 5% dextrose in normal saline (D5/0.9% NaCl)
Regulatory mechanisms
Baroreceptor reflex
Volume receptors
Renin-angiotensin-aldosterone mechanism
Antidiuretic hormone
Baroreceptor reflex
The primary reflex pathway for homeostatic control of blood pressure
Respond to a fall in arterial blood pressure
Located in the atrial walls, vena cava, aortic arch
and carotid sinus
Constricts afferent arterioles of the kidney resulting in retention of fluid
Renin-Angiotensin-Aldosterone
Renin
*Enzyme secreted by kidneys when arterial pressure or volume drops
* Interacts with angiotensinogen to form angiotensin I (vasoconstrictor)
Angiotensin
* Angiotensin I is converted in lungs to angiotensin II using ACE (angiotensin
converting enzyme)
* Produces vasoconstriction to elevate blood pressure
* Stimulates adrenal cortex to secrete aldosterone
Aldosterone
,* Mineralocorticoid that controls Na+ and K+ blood levels
* Increases Cl- and HCO3- concentrations and fluid volume
Aldosterone Negative Feedback Mechanism
* ECF & Na+ levels drop → secretion of ACTH by the anterior pituitary → release
of aldosterone by the adrenal cortex → fluid and Na+ retention
Antidiuretic hormone
Also called vasopressin
Released by posterior pituitary when there is
a need to restore intravascular fluid volume
* Release is triggered by osmoreceptors in the thirst center of the hypothalamus
* Fluid volume excess ⇒ decreased ADH
* Fluid volume deficit ⇒ increased ADH
Dehydration
Loss of body fluids ⇒ increased concentration of solutes in the blood and a rise in
serum Na+ levels
* Fluid shifts out of cells into the blood to restore balance
* Cells shrink from fluid loss and can no longer function properly
risk:
Confused, Comatose, Bedridden, Infants, Elderly, Enterally fed.
s/s
Irritability, Confusion, Dizziness, Weakness, Extreme thirst, ⇓ urine output, Fever,
Dry skin/mucous
membranes, Sunken eyes, Poor skin turgor, Tachycardia.
Hypovolemia
, Fluid Volume deficit
can be caused by:
bleeding, GI upset, trauma, fluid aspiration or removal.
s/s
decreased urine output
dry skin
tachycardia
hypotension
concentrated urine with increased specific gravity.
nursing considerations:
rehydrate, increased fall risk precautions (decreased bp) measure I+o
Hypervolemia
Fluid volume excess
can be caused by:
heart failure, kidney failure, liver cirrhosis, high sodium intake.
s/s
increased weight
increased blood pressure
wet lung sounds
edema
nursing considerations:
low sodium diet, raise HOB (Breathing) I+O chart, daily weights, diuretics
Shock
Arterial Blood Gasses
pH: 7.35 - 7.45
PaCO235
HCO3
- 45 mmHg 22-26 mEq/L
Sensible losses
Urination
Defecation
Wound drainage
Insensible losses
Evaporation from skin
respiratory loss through lungs
isotonic solution
No fluid shift because solutions are equally concentrated
* Normal saline solution (0.9% NaCl)
Hypotonic solution
Lower solute concentration
* Fluid shifts from hypotonic solution into the more concentrated solution to create
a balance (cells swell)
* Half-normal saline solution (0.45% NaCl)
Hypertonic solution
,Higher solute concentration
* Fluid is drawn into the hypertonic solution to create a balance (cells shrink)
* 5% dextrose in normal saline (D5/0.9% NaCl)
Regulatory mechanisms
Baroreceptor reflex
Volume receptors
Renin-angiotensin-aldosterone mechanism
Antidiuretic hormone
Baroreceptor reflex
The primary reflex pathway for homeostatic control of blood pressure
Respond to a fall in arterial blood pressure
Located in the atrial walls, vena cava, aortic arch
and carotid sinus
Constricts afferent arterioles of the kidney resulting in retention of fluid
Renin-Angiotensin-Aldosterone
Renin
*Enzyme secreted by kidneys when arterial pressure or volume drops
* Interacts with angiotensinogen to form angiotensin I (vasoconstrictor)
Angiotensin
* Angiotensin I is converted in lungs to angiotensin II using ACE (angiotensin
converting enzyme)
* Produces vasoconstriction to elevate blood pressure
* Stimulates adrenal cortex to secrete aldosterone
Aldosterone
,* Mineralocorticoid that controls Na+ and K+ blood levels
* Increases Cl- and HCO3- concentrations and fluid volume
Aldosterone Negative Feedback Mechanism
* ECF & Na+ levels drop → secretion of ACTH by the anterior pituitary → release
of aldosterone by the adrenal cortex → fluid and Na+ retention
Antidiuretic hormone
Also called vasopressin
Released by posterior pituitary when there is
a need to restore intravascular fluid volume
* Release is triggered by osmoreceptors in the thirst center of the hypothalamus
* Fluid volume excess ⇒ decreased ADH
* Fluid volume deficit ⇒ increased ADH
Dehydration
Loss of body fluids ⇒ increased concentration of solutes in the blood and a rise in
serum Na+ levels
* Fluid shifts out of cells into the blood to restore balance
* Cells shrink from fluid loss and can no longer function properly
risk:
Confused, Comatose, Bedridden, Infants, Elderly, Enterally fed.
s/s
Irritability, Confusion, Dizziness, Weakness, Extreme thirst, ⇓ urine output, Fever,
Dry skin/mucous
membranes, Sunken eyes, Poor skin turgor, Tachycardia.
Hypovolemia
, Fluid Volume deficit
can be caused by:
bleeding, GI upset, trauma, fluid aspiration or removal.
s/s
decreased urine output
dry skin
tachycardia
hypotension
concentrated urine with increased specific gravity.
nursing considerations:
rehydrate, increased fall risk precautions (decreased bp) measure I+o
Hypervolemia
Fluid volume excess
can be caused by:
heart failure, kidney failure, liver cirrhosis, high sodium intake.
s/s
increased weight
increased blood pressure
wet lung sounds
edema
nursing considerations:
low sodium diet, raise HOB (Breathing) I+O chart, daily weights, diuretics
Shock
