acid-base imbalancemydsn.net/docs-tools/nrs104/chapter-14-2.pdf · 2014. 3. 7. · alkalosis the...

Shu-Yi (Emily) Wang, PhD, RN, [email protected]

Denver School of Nursing

Acid-Base Imbalance

pH Ranges Compatible With Life

In blood, the pH represents the relationship between the respiratory and the metabolic systems. A normal pH in the human body is between 7.35-7.45

The first line of defense against pH disorders

Chemical buffer systems

If too much acid is present, the bicarbonate ions take up the hydrogen ions released by the acid and become carbonic acid, which is then excreted through the respiratory system in the form of carbon dioxide and water

Homeostatic mechanisms attempt to maintain balance at a ratio of HCO3- to PCO2

Partial pressure of CO2 being carried in the blood to lungs for excretionRepresents RESPIRATORY component

Represents the amount of bicarbonate present in the bloodRenal tubules regulate balance of hydrogen ions and bicarbonate inos

Acidosis: excrete hydrogen, reabsorb bicarbAlkalosis: retain hydrogen, excrete bicarb

Represents METABOLIC component

Metabolic Acidosis

Metabolic Alkalosis

Respiratory Acidosis

Respiratory Alkalosis

Figure 31.4 Acid-base imbalances.

An assessment to determine whether your patient’s ulnar & radial arteries are patent.Ask patient to rest hands facing upwards so you can examine color changesAsk patient to make a tight fist to begin forcing the blood from his handUsing your middle & index finger compress both radial & ulnar arteries to obstruct arterial blood flow to the handAsk patient to relax hand into a slightly flexed positionRelease pressure on the ulnar artery & continue to apply pressure to the radialartery. Note color. If they flush within 5 seconds, the ulnar artery is patent & Allen’sTest is “positive” for the ulnar artery.Repeat for the radial artery

Basic Steps to ABGs Interpretation

BE (±2 )

PaCO2 (35-45mmHg)

HCO3 (22-26 mEq/L)

PaO2 (80-100mmhg)

pH (7.35-7.45)

pH (7.35-7.45)

Using the Acid-Base Map

Developed by Charles Peshkin of EKG Skillbuilders

Represents 3 of the 4 elements of blood gas analysispH PCO2 HCO3

Resp. MetabolicAlkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5

Charles Peshkin/EKG Skillbuilders, 1996-99

Using the Acid-Base Map

pH = hydrogen ions decrease

“The higher the pH, the lower the concentration of H and the more basic (alkalotic) the blood is.”

pH = hydrogen ions increase

“The lower the pH, the higher the concentration of H & the more acidic the blood.”

pH PCO2 HCO3Resp. Metabolic

Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


Normal pH is 7.40

The range is 7.35 to 7.45

PaCO² = pressure of Carbon Dioxide

Respiratory system lowers (hypoventilation) and raises (hyperventilation) CO²to help maintain body pH to 7.40

breathing =

CO² ,

acid and

pH

(hypoventilation)

breathing =

CO² ,

acid and

pH

(hyperventilation)


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


Normal PaCO² is 40 mmHg

Normal range is 35-45 mmHg

HCO³ = Bicarbonate Ion Buffer

HCO³ combines with acid and decreases its ability to lower the pH

The kidneys excrete or retains the HCO³

HCO³ -

acid =

pH

HCO³ +

acid =

pH


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


Normal HCO³ is 24 mEqNormal range is 22 to 26 mEq

Example for Using The Map

The CO² is in the alkalotic range and this tells you that the respiratory system is contributing to the alkalosis

The HCO³ is in normal range and is not causing the alkalosis

Interpretation respiratory alkalosis related to a low CO² from hyperventilation


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.50

32 25


The pH is alkalotic.

The pCO² is normal

The kidneys have released higher levels of HCO³ to cause metabolic alkalosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.70

38

47

If all 3 values are abnormal in the same direction on the map, the condition is called a combined

problem


Combined means both the respiratory and metabolic systems are involved in the imbalance

Combined respiratory and metabolic acidosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


6.83

60

10


All values in alkalotic range

Combined respiratory and metabolic alkalosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.6827 32

If pH is abnormal; and PaCO² + HCO³ are abnormal in different

directions on the map, this condition is called a partially

compensated problem


Respiratory and metabolic values on opposite sides

The value that is on the same side as the pH is the cause of the pH abnormality

The value on the opposite side of the pH is trying to compensate

Kidneys are trying to compensate by releasing more HCO³ (balance through acidosis)

Partially compensated respiratory alkalosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.66 15

17


Two values on the same side is alkalosis

The value at the opposite side is trying to compensate by decreasing breathing and increasing CO²

Partially compensated metabolic alkalosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.53

49

41


pH and respiratory values are acidotic.

Respiratory is from hypoventilation

Kidneys respond by retaining HCO³ in an effort to raise the pH.

Partially compensated respiratory acidosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.28

62

29


pH and metabolic are both acidotic

The lungs are working to blow off CO² and raise the pH

Partially compensated metabolic acidosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.21

8

32

If the pH is normal; and the PCO² and HCO³ are both abnormal this is a compensated problem

Note: The pH will fall short a few hundredths of unit short of the 7.40 normal. The pH will be in the normal

range. Which side of 7.40 determines acidotic or alkalotic


As the pH nears normal values, the compensatory mechanisms begin to cease

This blood gas is slightly alkalotic.

The renal system lowered the pH, as the pH entered normal range, the renal system ceased the compensatory mechanisms a few hundredths short of 7.40

This is compensated respiratory alkalosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.42

28

18


As the pH nears normal values, the compensatory mechanisms begin to cease

This blood gas is slightly alkalotic.

The respiratory system highbred the pH, as the pH entered normal range, the respiratory system ceased the compensatory mechanisms a few hundredths short of 7.40

This is compensated metabolic alkalosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.45

67

46


Compensated respiratory acidosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.38

53

31


Compensated metabolic acidosis


Alkalosis 7.80 5 50

7.45 35 26

Normal 7.40 40 24

7.35 45 22

Acidosis 6.80 75 5


7.35

13

25

Acid-Base ImbalancepH Ranges Compatible With Life投影片編號 3投影片編號 4投影片編號 5投影片編號 6投影片編號 7投影片編號 8投影片編號 9投影片編號 10投影片編號 11投影片編號 12投影片編號 13投影片編號 14Metabolic Alkalosis投影片編號 16Respiratory Acidosis投影片編號 18Respiratory AlkalosisFigure 31.4 Acid-base imbalances.投影片編號 21投影片編號 22投影片編號 23投影片編號 24Basic Steps to ABGs InterpretationUsing the Acid-Base MapUsing the Acid-Base MapPaCO² = pressure of Carbon DioxideHCO³ = Bicarbonate Ion BufferExample for Using The MapExample for Using The Map投影片編號 32Example for Using The MapExample for Using The Map投影片編號 35Example for Using The MapExample for Using The MapExample for Using The MapExample for Using The MapIf the pH is normal; and the PCO² and HCO³ are both abnormal this is a compensated problem�Example for Using The MapExample for Using The MapExample for Using The MapExample for Using The Map

acid-base imbalancemydsn.net/docs-tools/nrs104/chapter-14-2.pdf · 2014. 3. 7. · alkalosis the...

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