Exam 1 Flashcards
(230 cards)
ventilatory status
See if they’re retaining or releasing carbon dioxide
BiPap to increase ventilation
If on ventilator, increase settings to have patient ventilate more
Contraindications of ABG
Bleeding disorder
AV fistula
Severe peripheral vascular disease, absence of an arterial pulse
Infection over site
Which artery to use for ABG
The radial artery is superficial, has collaterals, and is easily compressed. It should almost always be the first choice
Other arteries (axillary, femoral, dorsalis pedis, brachial) can be used in emergencies
what medicine is in ABG and what can it alter
heparin!
Preloaded dry heparin powder
Eliminates dilution problem
Mixing becomes more important
May alter sodium or potassium levels
air bubble in ABG
pO2 will begin to rise, pCO2 will fall
Oxygen is 21% of air
Oxygen concentration in blood is lower than air. Air goes from high concentration (bubble) to low concentration (blood), falsely elevating oxygen levels
CO2 concentration in blood is higher than air. CO2 goes from high concentration (blood) to low concentration (bubble), falsely decreasing CO2 levels
pH falsely elevated because of low CO2
Transporting ABG
After specimen is collected and air bubble is removed, gently mix and invert syringe
WBCs are active and will consume oxygen (PaO2 will decrease, PaCO2 will increase)
Get blood analyzed within 30 mins
Place ABG on ice to stop WBCs from being active
how to do ABG
Withdraw the needle and hold pressure on the site
Protect needle
Remove any air bubbles
Make sure blood is in contact with heparin
Gently mix the specimen by rolling it between your palms
Place specimen on ice and transport to the lab immediately
Pressure on the site and monitor for bleeding
Arterial vs venous pH
Arterial: 7.35-7.45
Venous: 7.32-7.42
Venous is lower because low O2 and high CO2
pH compatible with life
6.8-7.8
pH regulation methods
chemical buffer system
lungs
kidneys
why is bad pH harmful?
Bad pH denatures proteins
Chemical buffer system
Binds or releases H+
Intra and extracellular buffers
Three major chemical buffer systems
bicarb
phosphate
protein buffer systems
Extracellular buffer example equation
H2O+CO2=H2CO3=H+ +HCO3-
Intracellular buffers
Proteins, organic and inorganic phosphates, hemoglobin in RBC
Lungs in buffer system
regulates ventilation in response to CO2 in blood (CSF=central chemoreceptor)
Rise in partial pressure CO2 in arterial blood stimulates respiration, more powerful than the decrease of partial pressure of O2
How long do the lungs take to regulate pH
Takes minutes to activate, timing of peak compensation 1-24 hours
COPD and ventilation
Patients with COPD should NOT be over oxygenated because it will destimulate breathing
Kidneys in buffer system
Regulaes bicarb AND H+ by regenerating bicarb or absorbing them from renal tubular cells
How long do the kidneys take to regulate pH
hours to days (12h-5d)
Studies are done from healthy pts, no research from critically ill population
For which acid-base imbalance is the body’s compensatory system poorest
metabolic alkalosis
respiratory acidosis clinical manifestations
increased ICP (acute) due to: increased CO2 which leads to cerebrovascular dilation and increased cerebral blood flow
Papilledema and dilated conjunctival blood vessels
Hyperkalemia (H+ into cells means K+ comes out of cells and into blood)
Respiratory alkalosis manifestations
Lightheadedness from decreased cerebral blood flow
Inability to concentrate
Numbness and tingling (affect nerve function)
Dysrhythmias (hypokalemia)
metabolic acidosis due to loss of bicarb
hyperchloremic acidosis
diarrhea
lower intestinal fistula
Use of diuretics (carbonic anhydrase inhibitors such as acetazolamide, dorzolamide)
Early renal insufficiency
Excessive administration of chloride
Administration of parenteral nutrition without bicarb