Definitions and results

Normal pHpH (7.35-7.45)
< 7.35Acidosis
> 7.45Alkalosis
7.40is the exact normal



< 7.35 or > 7.45Uncompensated
CO2 (35-45)normal CO2 in artery
HCO3 (22-26)normal Bicarbonate in artery
Respiratory AcidosisCO2 > 45
Respiratory AlkalosisCO2 < 35
Metabolic AcidosisHCO3 <22
Metabolic AlkalosisHCO3 > 26
pH and HCO3 are cousinsthey go in the same direction for Acidosis and Alkalosis
But CO2 is an outsiderit goes the opposite direction for Acidosis and Alkalosis
Abnormal pH and CO2 in opposite directionsrespiratory problem
Abnormal pH and HCO3 in the same directionmetabolic problem
HCO3 and CO2 in the same directiontrying to compensate for abnormal pH
HCO3 and CO2 in opposite directionsboth imbalances (mixed)
What are some causes of low PaO2?Hypoxic Hypoxia--there’s just not enough of a supply of O2 ( COPD, pneumonia, ARDS, suffocation)
What are some causes of low PaO2?Anemic Hypoxia There’s plenty of O2—but not enough HGB to carry it to the tissues
What are some causes of low PaO2?Stagnant Hypoxia There may be enough O2 coming in and enough HGB to carry it--but the circulation is stagnant due to a decreased Cardiac Output. The O2 is not being adequately carried to the tissues.
What are some causes of low PaO2?Histotoxic Hypoxia Poisoning like Carbon Monoxide or Cyanide. Either the blood can’t carry the O2 or the cells can’t receive the O2 from the blood.
What is saturation?SaO2 (oxygen saturation) measures the percent of oxygen bound to hemoglobin. This tells weather the patient has HYPOXIA (decreased O2 in the tissues).
Normal SaO2 ?Greater that 95%
In Carbon Monoxide Poisoningthe HGB is saturated with Carbon Monoxide. Although the patient is hypoxemic because there is no room on the HGB for O2 to be carried—the Saturation looks good because it can’t distinguish between the two.
What does the PaO2 mean?The O2 tells us if the patient has HYPOXEMIA (decreased oxygen in the blood).
Normal PaO2 =80-100. (Hypoxemia = PaO2<80)
What does it do?PaO2 assesses Perfusion (gas exchange).
What does it do?PaCo2 asseses the adequacy of Ventilation (breathing pattern).
What does it do?The PaO2 is very important in determining your patient’s oxygen status and needs
Decreased pH with Decreased HCO3ACIDOSIS.
Increased pH with Increased HCO3ALKALOSIS.
Decreased pH with Increased CO2ACIDOSIS.
Increased pH with Decreased CO2ALKALOSIS.
If it is 7.35-7.45 (normal)is COMPENSATED
If the CO2 is <35 or >45--RESPIRATORY.
If the HCO3 is <22 or >26--METABOLIC.
If the pH is <7.35 or >7.45is UNCOMPENSATED.
Carbon Dioxide is anAcid
Increasing your respiratory rate(hyperventilation)you "blow off" CO2 decreasing your acid. Giving you ALKALOSIS
Decreasing your respiratory rate (hypoventilation)you retain CO2(acid) therefore increasing your CO2 giving you ACIDOSIS
Hydrogen or HCO3 is Bicarbonate orBasic or a base
If you have excess H+ and decreased HCO3(base):decrease in pHAcidosis; the kidneys will try to adjust to this by excreting H+ and retaining HCO3
When H+(acid) decreases and you hace increased HCO3(base)Alkalosis;Kidneys excrete HCO3(base), retains H+
Respiratory Acidosis:pH<7.35;CO2>45Causes HypoventilationDepression of respiratory center (sedatives, narcotics,drug overdose, mi,Spinal cord injuryChest wall disorders(pnuemo)Disorders of lung(COPD, CHF, pneum, aspiration
S/S of Respiratory AcidosisMuscle twichingTachycardiadysrythmiasdiaphorisispalpitationsserum electrolyte abnomalitiesCNS depression
Treatment of respiratory acidosisphysically stimulate pt to breatheVigorous chest PTC & DB, Spirometerrespiratory treatmentsreversal of sedativesantibiotics for infectionsdiuretics for oveload
Respiratory Alkalosis: pH > 7.45 CO2 < 35Alveolar HyperventilationPsychogenic(fear,pain,anxiety)CNS stimulation(brain injury, ETOH, brain tumorHypoxiaventilator rate too fast
S/S of respiratory alkalosisHeadacheVertigoTinnitusElectrolyte abnormalitiesParesthesias
Treatment for AlkalosisSedatives or analgesicsCorrection of HypoxiaAntipyretics for fevertreat for hyperthyroidismbreathe into a paper bag

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