RPT 223 Module 1
what is the best indicator of tissue oxygenation?
PvO2
what are clinical signs of inadequate cardiac output?
fatigue, hypotension, metabolic acidosis, bradycardia, and pulmonary edema
pH: 7.40 PaCO2: 62 PaO2: 89 HCO3: 38 FiO2: .58
fully compensated respiratory acidosis with corrected hypoxemia
respiratory alkalosis
high pH, low CO2
what are some causes of hypoxemia?
hypoventilation (drug overdose), v/q mismatch (COPD), pulmonary shunting (ARDS), diffusion defect (pulmonary fibrosis), and low PiO2 (altitude sickness)
what would cause tissue hypoxia w/normal arterial oxygentation?
inadequate cardiac output
what is the direct effect of an increase PaCO2 on HCO-3?
increase
an decrease of pH on the oxyhemoglobin dissociation curve will shift in what direction?
left
respiratory acidosis
low pH, high CO2
a mixed metabolic acidosis and respiratory alkaosis are likely when the pH and HCO-3 are low and the PaO2 is
lower than the predicted
associated w/ABG sampling, air in the sample will have what effect?
lowers Pco2 and high Po2, raises pH and low Po2
associated w/ABG sampling, excess liquid heparin will have what effect?
lowers Pco2 and high Po2, raises pH and low Po2
an 80 yo pt has a PaO2 of 71mmHg. how would you describe this finding?
mild hypoxemia
given the following ABG results, interpret the acid base status: pH 7.42, PaCO2 56mmHg, HCO-3 35mmol/L
mixed metabolic alkalosis and respiratory acidosis
given the following ABG results, interpret the PaO2 status: pH 7.21, PaO2 53mmHg, PaCO2 67mmHg, HCO-3 26mmol/L, BE +2mmol/L.
moderate hypoxemia
thermal injury from TC monitors can be avoided by?
monitoring sensor temperature and rotating the site
pH: 7.42 PaCO2: 37 PaO2: 92 HCO3: 23 FiO2: .21
normal ABG & normal oxygenation
a 17 yow is brought into ED vitals are: pulse 100bpm, RR 4 bpm, and BP 100/65. the pt was at a party where he was discovered by his friends to be slumped in a chair and unresponsive. ABG results show: pH 7.24, PaCO2 68mmHg, HCO-3 28mmol/L, BE +1mmol/L. the pts acid base status is classified as what?
uncompensated respiratory acidosis
postanalytic error
problem occurring after sample analysis that can alter the accuracy of blood gas results
Preanalytic error
problem occurring before sample analysis that can alter the accuracy of blood gas results
a pt. breathing 40% O2 has a markedly higher than normal P(A-a)O2, which doesnt improve when the O2 concentration is increased to 50%. what is the most likely cause of her hypoxemia?
pulmonary shunting
What is the preferred site for an ABG method?
radial
associated w/ABG sampling, venous blood or venous samplying will have what effect?
raises Pco2 , lowers pH and can greatly lower Po2
associated w/ABG sampling, metabolic effects will have what effect?
raises Pco2, lowers pH and Po2
given the following ABG results, interpret the acid base status: pH 7.21, PaO2 53mmHg, PaCO2 67mmHg, HCO-3 26mmol/L, BE +2mmol/L.
uncompensated respiratory acidosis
pH: 7.25 PaCO2: 57 PaO2: 74 HCO3: 24 FiO2: .32
respiratory acidosis with uncorrected mild hypoxemia
the Pco2 is measured by what electrode in blood gas analyzer?
severinghaus
what infection control precaution would you apply when obtaining ABG?
standard precautions plus face shield
For respiratory acidosis to be paritally compensated what has to occur?
the HCO3 would be high and the pH would be close to normal or normal
For respiratory acidosis to be fully compensated what has to occur?
the HCO3 would be high and the pH would not be normal
For respiratory alkalosis to be paritally compensated what has to occur?
the HCO3 would be low and the pH would be close to normal
For respiratory alkalosis to be fully compensated what has to occur?
the HCO3 would be low and the pH would be normal
For metabolic acidosis to be paritally compensated what has to occur?
the PaCO2 would be low and the pH would be close to normal
For metabolic acidosis to be fully compensated what has to occur?
the PaCO2 would be low and the pH would be normal
For metabolic alkalosis to be paritally compensated what has to occur?
the PaCO2 would rise and the pH close to normal
For metabolic alkalosis to be fully compensated what has to occur?
the PaCO2 would rise and the pH would be normal
continuous noninvasive assessment of pt. oxygenation can be provided by?
trancutaneous Po2 and pulse oximetry
True or False: the pH electrode uses a separate reference electrode
true
True or False: when you have a mixed acid base balance you would not see a compensation.
true
a pt has the following ABG results: pH 7.33, PaCO2 35mmHg, HCO-3 18mmol/L, BE -7mmol/L. bases on these findings the pt has what?
uncompensated metabolic acidosis
pH: 7.48 PaCO2: 30 PaO2: 88 HCO3: 23 FiO2: .21
uncompensated resp. alkalosis with correct hypoxemia
pH: 7.51 PaCO2: 40 PaO2: 78 HCO3: 31 FiO2: .35
uncompensated resp. alkalosis with uncorrected mild hypoxemia
a pulmonary shunt value of what indicates a potentially life threatening clinical situation?
35%
PaCO2
35-45 mmHg
moderate hypoxemia
40-59
mild hypoxemia
60-79
pH
7.35-7.45
PaO2
80-100 mmHg
normal rang of anion gap
9-14 mEq/L
metHb
<1.5%
metabolic acidosis
<22 mEq/L
CoHb
<3%
serve hypoxemia
<40
what are common causes of metabolic acidosis?
Diabetic ketoacidosis, lactic acidosis, renal failure, diarrhea, hyperalimentation, ingestion of acids, loss of base, and pancreatic fistula
anion gap
Difference between the concentrations of serum cations and anions, used to help differentiate among causes of metabolic acidosis
BE
(+)(-) 2mmol/L
metabolic alkalosis
>26 mEq/L
SaO2
>95%
to evaluate a pts acid base status, you would recommend what?
ABG
Mixed acidosis
Low pH High PaCO2 Low HCO3-
anemia
total Hb content is low
under ideal conditions of temperature, pressure and relative humidity analyzers are within what percentage?
1%
for the test of collateral circulation in an Allen's test, "pinking up" of the hand is normal if it occurs within?
10 to 15 seconds
Hb
12-18 g/dL
CaO2
16-20 ml/dl
HCO-2
22-26 mmol/L
an arterial pressure site normally should be compressed for a minimum of what after puncture?
3 to 5 minutes
what is the normal value of an anatomic shunt of the lung?
3%
what is the best indicator of metabolic acid base status?
BE
to measure actual blood O2 saturation, you would recommend?
CO- oximetry
what is the best used to assess arterial oxygenation?
CaO2
what parameters is the respiratory component of acid base status?
PaCO2
hypocapnia
PaCO2 below 35mmHg, occurs when alveolar ventilation exceeds CO2 production (hyperventilation)
hypercapnia
PaCo2 above 45mmHg, occurs when the level of alveolar ventilation is nor sufficient to remove CO2 production (hypoventilation)
the blood gas results from a pt. breathing a confirmed O2 concentration of 30% indicate a PaO2 of 250mmHg, based on this datum, it can be concluded that the
PaO2 is in error and should be remeasured
During metabloic acidosis if the PaCo is not low then there is what defect as well?
Respiratory
Calibration
exposing a measurement device to two or more know levels of measurements to confirm proper zeroing, gain, and linerarity
hyperoxemia
abnormally high PaO2 value
right decrease in HbO2 of the oxyhemoglobin dissociation curve causes?
acidosis, hypercapnia, and fever
iatrogenic alkalosis
alkalosis caused by medical intervention; most often a respiratory alkalosis caused by overly aggressive mechanical ventilation
Left increase in HbO2 of the oxyhemoglobin dissociation curve causes?
alkalosis, hypocapnia, and hypothermia
before an ABG sample is obtained the clotting parameters should be evaluated because?
bleeding time may be prolonged if they are abnormal
Before an ABG is obtained, the patient's clotting parameters should be evaluated because:
bleeding time maybe prolonged if they are abnormal
What is the primary method of transporting O2 in the blood?
bound to Hb
given the following ABG results, interpret the acid base status: pH 7.14, PaCO2 55mmHg, HCO-3 18.
combined respiratory and metabolic acidosis
given the following ABG result interpret the acid base status: pH 7.45, PaCO2 25mmHg, HCO-3 17mmol/L, BE -6mmol/L.
compensated respiratory alkalosis
a shift to the right in the oxyhemoglobin dissociation cureve has what effect on the affinity of Hb for O2?
decrease
hypoxia
decrease in tissue oxygenation
Abnormal Hb
dyschemoglobin
Analytic errors
error occurring the analysis or measurement phase of laboratory test
What are some indications for an ABG sampling?
evaluate ventilation, acid base, assess the pts. response to therapy, monitor the severity and progression of a disease
what is often the first clinical sign that suggest the presence of hypoxemia?
exertional dyspnea
the negative log of the hydrogen ion concentration is defined as
pH
Henderson-Hasselbalch equation
pH = 6.1 + log [HCO3-]/(.03*Pco2)
mixed alkalosis
pH high PaCO2 low HCO3 high
alkalemia or alkalosis
pH higher than 7.45
acidemia or acidosis
pH lower than 7.35
pH: 7.12 PaCO2: 60 PaO2: 48 HCO3: 29 FiO2: .4
partially compensated resp. acidosis with uncorrected moderate hypoxemia
pH: 7.51 PaCO2: 27 PaO2: 116 HCO3: 21 FiO2: .50
partially compensated respiratory alkalosis with over-corrected hypoxemia
pH: 7.46 PaCO2: 49 PaO2: 47 HCO3: 34 FiO2: .25
partially uncompensated metablic alkalosis with uncorrected moderate hypoxemia
a 35 yo 54 kg woman w CHF enters ER w/SOB. An ABG sample shows: pH 7.51, PaCO2 30mmHg, HCO-3 23mmol/L, Be +1mmol/L. these results indicated what?
uncompensated respiratory alkalosis
what is the most common physiologic cause of hypoxemia in pts w/ lung disease?
v/q mismatch
hyperventilation
ventilation greater than necessary to meet metabolic needs, <35mmHg (respiratory alkalemia)
hypoventilation
ventilation less than necessary to meet metabolic needs, >45mmHg (respiratory acidemia)
dead space ventilation
ventilation that doesnt participate in gas exchange
