Haemodynamic Monitoring Flashcards
Preload
Filling pressure in ventricles at end of diastole - the amount of blood volume in the ventricles at end of diastole
After load
The pressure the ventricles produce to overcome the resistance to ejection. The resistance the ventricles must push against with systolic ejection
Medication to reduce preload
Diuretic
Vasodilator- GTN
Morphine - dilated venous system
Medication to increase preload
Fluid for low flow or shocked states
Medications to reduce after load
ACE inhibitors-
Medications to increase after load
Need to constrict- vasopressors
What is contractility
Force of myocardial contraction - related to preload and after load
Positive inotrope to improve contractility
Dobutamine
Negative inoptrope to reduce contractility
Beta blockers- preserve myocardium oxygen consumption
Indications for an artline
Labile BP (easily altered)
Compromised CO, tissue percussion or fluid volume status
Anticipation of haemodynamic instability
Titration of vasoactive drugs- inotrope support.
Frequent arterial blood sampling
Morbid obese
Common sites for an artline
Radial ( most common), femoral. Umbilical (neonates)
Indications for central venous pressure monitoring
Monitor fluid status (CVP) Administer lge volumes of fluids Administer drugs and irritant drugs, TPN Long terms access Difficulty obtaining other access
Major sites for Central lines
Femoral, external jugular, internal jugular, subclavian
What is a normal CVP
0-8 mmHg
Causes for raised CVP
Volume overload R) ventricular AMI Cardiac failure Cardiac tamponade Constrictive pericarditis Pulmonary HTN
Cause for reduced CVP
Dehydration
Hypovolemic shock
Distributive shock states
Diagrammatically express the central venous pressure wave form and relate to cardiac cycle
3 peaks
A wave - atrial contraction, correlates to PR interval
C wave - closure of the tricuspid valve, correlates to QRS complex
V wave - atrial filling - correlates to t-p interval
2 descents
X descent - atrial relaxation
Y descent - tricuspid valve reopens
Metabolic acidosis
Decreased HCO3
Normal range 22-26mmol/L
Value indicates how much has been used in buffering acids in the blood
Metabolic alkalosis
Elevated HCO3
Normal range 22-26 mmol/L
Causes of respiratory acidosis
CNS/ respiratory centre depression Hypo ventilation Lung disease Airway obstruction Neuromuscular interference
Causes of metabolic acidosis
Excessive loss HCO3 (diarrhoea, renal tubular acidosis) Increased production of H+ (keto acidosis) Ingestion toxins increase lactate production Altered cellular metabolism (lactic acidosis) Renal failure (decreased excretion H+)
Causes of respiratory alkalosis
Hyperthyroidism Hypoxia, hypoxaemia Hyperventilating/ CNS irritation Anxiety Drugs - salicylates Lung disorders
Causes of metabolic alkalosis
Mechanical ventilation Fever/sepsis Cl- wasting diarrhoea Vomiting Citrate in blood transfusions NG suctioning Liver failure Over use antacids Diuretics
Why is an Allen’s test performed
Should be done prior to artline insertion.
To determine that there is sufficient collateral circulation to and from the ulnar artery of the limb
Fast flush/ square wave test on artline
Squeeze the flush device we then get a quick upstroke that squares off at the top and goes back down. Should see 1-2 oscillations after the square is a good wave form
Over damped wave form
No dicrotic notch, no oscillations after fast flush
“ getting rained on”
To correct: check for blood clots, blood in catheter, air bubbles
Use low compliance (rigid) short monitoring tubing
Check for kinks in line
Underdamped wave form
“Falsely high systolic”
High peaks , Ringing, repeated oscillations
More than 2 oscillations are not normal.
Remove air bubbles, use lge bore, shorter tubing
Complications of an art line
Embolus, ishcemia, infection
Indication for a cvc
Provides an indication of right ventricular filling pressure to guide fluid administration
Complications of CVC insertion
Pneumothorax, sepsis, arrhythmias
What assessment needs to be performed to confirm placement of CVC prior to fluid administration
Chest X-ray
