Fluid & Electrolyte Balance Flashcards
What is Osmolarity
Amount of solutes per LITRE of a solution (VOLUME)
What is Osmolality
Amount of solutes per KILOGRAM of a solution (WEIGHT)
What is Hydrostatic pressure
Ability to push a solution across a membrane
What is oncotic pressure
Ability to attract/pull a solution across a membrane
What is Tonicity
A measurement of Osmotic/Oncotic pressure
Explain uses, and con’s of CSL/Hartmanns
Restores circulating volume & electrolyte deficits
Used in Burns, Acidosis, Hypovolaemia
Readily available, low cost, buffer
X = rapid movement from intravascular space to the extravascular space
Explain uses, pros and cons of Normal Saline
Restores circulating volume and is compatible with most drugs
Readily available, safe to use, low cost
X = Can cause Hypercholoraemia acidosis with prolonged
use
Explain uses, pros and cons of 1/2 normal saline
Hypotonic solution used in DKA, Hypertonic Dehydration, Sodium Chloride depletions, Gastric fluid loss
Maintains body fluid, Establishes renal function, OK for diabetics (No glucose)
X = Can cause cardiovascular collapse, Increase ICP, Do not use in Trauma, burns or Liver Disease
Explain uses, pros and cons of D5W
Raises fluid volume and has excretory properties. Isotonic in the bag but becomes hypotonic once metabolised in the body.
No sodium, use in dehydrations, hypernatraemia
X = Can lead to hyperglycaemia or Overload. Not calorifically complete.
Explain what Packed Red Blood Cells are used for and the infusion time
Restores intravascular volume in Trauma, Surgery or Cancer patients. Replaces 02 - carrying ability of the blood in Anaemia.
Infuse over 1 to 3 hours
Explain what Platelets are used for and the infusion time
To treat haemorrhage in major trauma or surgery, clotting disorders, cancer or leukaemia patients.
Infuse over 15 to 30 minutes
Explain what Fresh Frozen Plasma is used for and the infusion time
Replaces clotting factors and other blood proteins.
Infuse over 30 minutes
What is the Pathophysiology, Signs and symptoms, and treatment of a Haemolytic Transfusion Reaction
A systemic reaction provoked by immunologic RBC incompatibility.
Can be immune or non-immune mediated
Occurs within first 24 hours of transfusion
Signs and symptoms = Increased temp and HR, Anxiety, Flank pain, Rigors, Dyspnoea, Pain at IV site.
Treatment = Stop the transfusion Check and monitor Vital signs Maintain IV access without flushing existing line (use new if required) Check pack, documentation and patient ID Notify MO and transfusion provider
What is Preload and the factors which influence it
The amount of myocardial stretch prior to contraction. Influenced by anything that affects Ventricular volume at the end of diastole.
- Circulating Volume
- Contractility of Myocardium
- Heart rate
- Atrial contraction
- Systemic and Pulmonary pressures
What is Afterload and the factor which influence it
The amount of resistance the heart must overcome to open the Aortic valve and propel blood into systemic circulation.
- Peripheral Vascular resistance (Vessel length, diameter, and blood viscosity)
- Contractility of the Myocardium
- Volume of Blood in Ventricle (LVEDV)
What are the 4 main forces that determine fluid movement in the capillaries and interstitial space
Capillary Hydrostatic pressure - (BP) forces out of capillary to interstitium
Capillary Oncotic pressure - Proteins attract fluid from interstitium to capillaries
Interstitial Hydrostatic pressure - Fluid within interstitium forces out of interstitium and into capillaries or Lymphatic vessels
Interstitial Oncotic - Proteins in interstitium attract fluid from the capillaries into the interstitial space
How does an increase in capillary hydrostatic pressure or decrease in capillary oncotic pressure lead to oedema
Fluid balance relies on constant pressures.
Abnormal increases in capillary hydrostatic pressure forces excess fluid into the interstitial space. Abnormal decrease in capillary oncotic pressure reduces the ability of fluid to be drawn back into the capillaries
What is ment by fluid being in the third space
Fluid that accumulates outside a normal fluid compartment
What are the different body fluid compartments
Intracellular compartment - Fluid within the cells
Extracellular compartment - All fluid outside the cells
- —>Interstitial compartment - The space between cells and outside blood vessels
- —> Intravascular - Plasma
How are Sodium, Chloride and Potassium normally kept in balance
The kidneys reabsorb Sodium which forces the active transport of Chloride also.
Potassium is secreted into filtrate and excreted via the urine, and sweat
What are some common causes of water deficit
Insufficient fluid intake Excess sweating Overuse of diuretics Vomiting and Diarrhoea Severe wound drainage Haemorrhage
What metabolic dysfunctions occur in Hyper/Hypo kalaemia
Hyper - Muscle cramps and hyperactive reflexes Respiratory distress urine abnormalities Decreased cardiac contractility ECG changes
Hypo- Alkalosis Shallow resps Irritability, confusion, drowsiness Thready pulse Decreased GI motility
What is the most prominent ECG change in HYPOkalaemia
U wave formation
What is the most prominent ECG change in HYPERkalaemia
Peaked T wave
What is the normal pH, HCO3, CO2 and Base Excess levels in the blood
pH: 7.35 - 7.45
CO2: 35 - 45
HCO3: 22 - 26
B/E: +/- 2 mEq/L
What is base excess
Meausres the metabolic component of the acid-base balance.
It is the amount of acid required to restore a litre of blood to its normal pH at a PaCO2 of 40 mmHg
How does hyperglycaemia contribute to dehydration and metabolic acidosis
Excess glucose molecules pass into the filtrate, attracting more fluid via osmotic pressure, which leads to Glycosuria and excessive fluid loss in the urine, thus dehydration :)
In diseases such as T1DM, a complete lack of insulin means that the circulating glucose is unable to be taken up and utilised for fuel. The body begins to break down liver glycogen stores and then fat stores. This produces fatty acids and ketones, resulting in metabolic acidosis.
What are 5 risk factors associated with developing fluid, electrolyte and acid-base imbalnces
Diuretic medication use Endocrine dysfunction Vomiting + Diarrhoea Kidney + Liver disease Excessive sweating
What are the clinical implications of Hypovolaemia
Hypovolaemia can progress to insufficient circulating volume and hypovolaemic shock. It manifests as tachycardia, hypotension, rapid weight loss, dry skin and mucous membranes, and reduced urine output
What are the clinical implications of Hypervolaemia
Hypervolaemia is an excess of fluid and increases the circulating blood volume. It causes increased BP and can lead to oedema and heart failure
What is ADH
A hormone secreted by the posterior pituitary gland that regulates water excretion from the kidneys
How does ADH work
Decreased blood pressure or volume and increased serum osmolality triggers the secretion of ADH.
ADH increases the permeability of the distal convoluted tubule and collecting ducts to water, reducing fluid loss.
In fluid excess, ADH is inhibited which decreases water reabsorption and leads to more fluid loss.
Define Arterial Blood Gases (ABG’s)
A lab test used to evaluate acid-base balance and gas exchange. Measures the arterial amount of oxygen, carbon dioxide and bicarbonate
Define PaO2
The partial pressure of oxygen in arterial blood
Define PaCO2
The partial pressure of carbon dioxide in arterial blood
Define Haematocrit
The ratio of the volume of RBCs to the total volume of blood
What is Osmotic pressure
The power of a solution to draw water across a membrane
What is Tonicity
Refers to the effect a solution’s osmotic pressure has on water movement across the membrane of cells within that solution
What is the mechanism of action of Potassium sparing diuretics
Inhibit potassium excretion and block sodium reabsorption at the distal convoluted tubule and collecting duct. Creating a concentration gradient that draws water out
e.g - AMILORIDE
What is the mechanism of action of Thiazide diuretics
Inhibit Sodium Chloride reabsorption between the ascending loop and beginning of the distal convoluted tubule
e.g - HYDROCHLOROTHIAZIDE
What are some causes of Metabolic Acidosis (SKID)
Ketoacidosis, Shock, Sever Diarrhoea, Impaired Kidney function
What are some signs and symptoms of Metabolic Acidosis (HALK)
Headache, Lethargy, Anorexia, kussmals breathing, nausea, diarrhoea, GI cramps, coma, arrhythmias
What are some causes of Metabolic Alkalosis (LDPC)
Loss of GI secretions, Diuretic use, Primary Hyperaldosteronism, Cushing’s syndrome
What are some signs and symptoms of Metabolic Alkalosis (DRAT)
Restlessness, lethargy, Nausea, vomiting, diarrhoea, dizziness, irritability, hypoventilation, arrhythmias, tachycardia
What are some causes of Respiratory Acidosis
Hypoventilation, hypercapnia, decreased alveolar compliance, COPD, drug overdose, chest trauma, neuromuscular disease
What are some causes of Respiratory Alkalosis (HHHHPE)
Hyperventilation, hypocapnia, hypoxia, pulmonary embolism, fever, anxiety, high altitudes
Explain the mechanism of action of Frusemide
Inhibits Sodium Chloride reabsorption at the Loop of Henle
Explain the uses and nursing considerations of MANNITOL
Promotes excretion of fluid via osmosis. Used in Oliguric diuresis, to decrease cerebral oedema and eliminate toxins.
Can cause fluid overload, electrolyte imbalance, Cellular dehydrations and necrosis
What are the manifestations of MILD hypovolaemic shock (15-30% loss)
BP - unchanged HR =/>100bpm RR >20 Neuro Slightly anxious Urine =/> 30mL/hr Capillary refill Normal
What are the manifestations of MODERATE hypovolaemic shock (30 - 40% loss)
BP - Lowered HR =/> 120bpm RR > 30 Neuro - Anxious/Confused Urine 20-30mL/hr Capillary refill >4 secs
What are the manifestations of SEVERE hypovolaemic shock (=/> 40% loss)
BP =/< 90 systolic HR =/> 140bpm Neuro - Confusion/Lethargy Urine 5 -15 mL/hr Capillary refill > 4 secs
Explain the Baroreceptor Reflex
A rapid negative feedback loop mechanism that maintains BP
Increased BP causes the PARASYMPATHETIC nervous system to reflexively decrease HR and contractility, decreasing BP
Decreased BP causes the SYMPATHETIC nervous system to increase HR and contractility, increasing BP
