4. Example homeostatis in human body
Example homeostatis in human body
Example homeostatis in human body
Example homeostatis in human body
Acid-base (pH) balance, body temperature,
Calcium and Phosphate level, blood glucose, fluid
volume, blood pressure etc.
Prepared by NLERT Feb,2015
6. Importance of acid base (pH) balance
Importance of acid base (pH) balance
Importance of acid base (pH) balance
Importance of acid base (pH) balance
If the pH changes whether up or
down:
1. protein and enzymes becomes stop
functioning.
2. muscles and nerves becomes
weakening.
3. metabolic activities becomes
impaired.
4. blood pH below 6.9 or above 7.9 would
be life threatening.
Prepared by NLERT Feb,2015
7. Carbonic acid
Carbonic acid
Carbonic acid
Carbonic acid -
-
-
-Bicarbonate
Bicarbonate
Bicarbonate
Bicarbonate
Buffering System
Buffering System
Buffering System
Buffering System
A major buffer system in the acid-base balance.
To alter any acid base imbalance thus maintain a
constant plasma pH.
Base on carbonic acid equilibrium equation and involve
2 systems: lung and kidney
Prepared by NLERT Feb,2015
8. Carbonic acid
Carbonic acid
Carbonic acid
Carbonic acid -
-
-
-Bicarbonate
Bicarbonate
Bicarbonate
Bicarbonate
Buffering System
Buffering System
Buffering System
Buffering System
The way of 2 systems interact is through the formation of
carbonic acid (H2CO3).
Movement through the carbonic acid system is tend
maintain a equilibrium status.
If necessary, H2CO3 can break up to form either H+ and
HCO3 or CO2 and H2O
The system works in both directions.
By balancing back and forward, a normal pH is achieved.
Prepared by NLERT Feb,2015
9. Renal mechanisms
Can eliminate large amounts of acid (H+)
Excretion or retention of base (HCO3-)
Can reserve and produce bicarb ions
HCO3 ion + Na ion NaHCO3
Most effective regulator of pH but slow
Prepared by NLERT Feb,2015
10. Respiratory mechanisms
Exhalation of carbon dioxide
Excretion and retention of CO2
Adjust body pH by changing rate and
depth of breathing
Prepared by NLERT Feb,2015
13. Acidosis and alkalosis:
Acidosis and alkalosis:
Acidosis and alkalosis:
Acidosis and alkalosis:
There are two abnormalities of acid-base
balance:
Acidosis: Too much acid or too little base,
resulting in a decrease in blood pH7.35
Alkalosis: Too much base or too little acid,
resulting in an increase in blood pH7.45
14. Metabolic or Respiratory
Metabolic or Respiratory
Metabolic or Respiratory
Metabolic or Respiratory
acid base imbalance
acid base imbalance
acid base imbalance
acid base imbalance
Acidosis and alkalosis are categorized as metabolic
or respiratory
Depends on their primary cause.
1. Metabolic acidosis and metabolic alkalosis are caused by
an imbalance acids or bases production or excretion by the
kidneys.
2. Respiratory acidosis and respiratory alkalosis are caused
by amount of carbon dioxide exhalation due to lung or
breathing disorders.
15. Cause of Respiratory Acidosis
Cause of Respiratory Acidosis
Cause of Respiratory Acidosis
Cause of Respiratory Acidosis
Lung diseases e.g. COPD, asthma or pneumonia.
Airway obstruction e.g. swelling, sputum retention.
Drugs (anesthetics, sedatives, and narcotics)
induce respiratory depression.
Neuromuscular diseases impair breathing effort.
Chest wall desfunction or deformities.
Prepared by NLERT Feb,2015
16. Cause of Metabolic Acidosis
Cause of Metabolic Acidosis
Cause of Metabolic Acidosis
Cause of Metabolic Acidosis
DKA (metabolism of amino acid
ketoacidosis)
Lactic acidosis (anaerobic metabolism during heavy
exercise, hypoxia or CPR)
Chronic renal failure
Diarrhea (excreted large amounts of bicarbonate).
DO: methanol or excessive salicylate drug (aspirin)
Prepared by NLERT Feb,2015
17. Cause of Respiratory Alkalosis
Cause of Respiratory Alkalosis
Cause of Respiratory Alkalosis
Cause of Respiratory Alkalosis
Hyperventilation (rapid, deep breathing)
Mechanical overventilation
Anxiety
Fever
Sepsis
Prepared by NLERT Feb,2015
18. Cause of Metabolic Alkalosis
Cause of Metabolic Alkalosis
Cause of Metabolic Alkalosis
Cause of Metabolic Alkalosis
Loss of H ions from the GI tract (free drain of R/T,
R/D, vomiting, nasal gastric suctioning).
Diuretics use such as Frusemide.
Excessive NaHCO3 use.
Massive blood transfusion (metabolism of
citrate
HCO3)
Prepared by NLERT Feb,2015
20. Compensation
Compensation
Compensation
Compensation
If pH is out of balance because of primary respiratory
disorder.
Renal system will make the corrections of pH.
If the renal system is the primary cause of pH disorder.
Respiratory system will make the corrections of pH.
This is called compensation.
Prepared by NLERT Feb,2015
21. Indications of ABG
Indications of ABG
Indications of ABG
Indications of ABG
1. Assess respiratory function: PaO2, PaCO2
2. Assess metabolic status (Acid-Base)
3. Assess any electrolyte imbalance
Prepared by NLERT Feb,2015
22. Factors affecting ABG results
Factors affecting ABG results
Factors affecting ABG results
Factors affecting ABG results
1. Temperature
2. The presence of air bubbles in ABG sample
3. Excessive heparin sodium in the sample
4. Clotted sample
5. Time between taken and analysis
6. Site of sampling (venous, arterial)
Prepared by NLERT Feb,2015
23. pH 7.35-7.45
pCO2 35-45mmHg or
4.7 -6 kPa
pO2 80-100mmHg or
10.3-13.3 kPa
O2 saturation 95-100%
HCO3- 22-26mEq/L
Base Excess + 2
Normal range
Normal range
Normal range
Normal range
Prepared by NLERT Feb,2015
24. Test
Test
Test
Test Normal
Normal
Normal
Normal ↓
↓
↓
↓ Value
Value
Value
Value ↑
↑
↑
↑ Value
Value
Value
Value
pH
pH
pH
pH 7.35
7.35
7.35
7.35-
-
-
-7.45
7.45
7.45
7.45 Acidosis
Acidosis
Acidosis
Acidosis Alkalosis
Alkalosis
Alkalosis
Alkalosis
pCO2
pCO2
pCO2
pCO2 35
35
35
35-
-
-
-45mmHg
45mmHg
45mmHg
45mmHg
Or
Or
Or
Or
4.7
4.7
4.7
4.7-
-
-
-6Kpa
6Kpa
6Kpa
6Kpa
Alkalosis
Alkalosis
Alkalosis
Alkalosis Acidosis
Acidosis
Acidosis
Acidosis
HCO3
HCO3
HCO3
HCO3 22
22
22
22-
-
-
-26
26
26
26 mEq
mEq
mEq
mEq/L
/L
/L
/L Acidosis
Acidosis
Acidosis
Acidosis Alkalosis
Alkalosis
Alkalosis
Alkalosis
pO2
pO2
pO2
pO2 80
80
80
80-
-
-
-100 mmHg
100 mmHg
100 mmHg
100 mmHg Hypoxemia
Hypoxemia
Hypoxemia
Hypoxemia ________
________
________
________
SaO2
SaO2
SaO2
SaO2 95
95
95
95-
-
-
-100%
100%
100%
100% Hypoxemia
Hypoxemia
Hypoxemia
Hypoxemia ________
________
________
________
↓
↓
↓ ↑
↑
↑
Prepared by NLERT Feb,2015
25. 6 Easy Steps to ABG
6 Easy Steps to ABG
6 Easy Steps to ABG
6 Easy Steps to ABG
Interpretation
Interpretation
Interpretation
Interpretation
(1)Is the pH normal?
(2)Is the CO2 normal?
(3)Is the HCO3 normal?
(4)Match the CO2 or HCO3 with the pH?
(Identifying primary cause)
(5)Does the CO2 or HCO3 in the opposite direction
of the pH?
(Compensation)
(6)Are the PaO2 and SaO2 normal?
Prepared by NLERT Feb,2015
26. Step 1: pH analysis
Step 1: pH analysis
Step 1: pH analysis
Step 1: pH analysis
Normal range of blood pH: 7.35 to
Normal range of blood pH: 7.35 to
Normal range of blood pH: 7.35 to
Normal range of blood pH: 7.35 to
7.45
7.45
7.45
7.45
pH 7.35 is acidic
pH 7.35 is acidic
pH 7.35 is acidic
pH 7.35 is acidic
pH. 7.45 is alkalotic
pH. 7.45 is alkalotic
pH. 7.45 is alkalotic
pH. 7.45 is alkalotic
Prepared by NLERT Feb,2015
27. Step 2: CO2 analysis
Step 2: CO2 analysis
Step 2: CO2 analysis
Step 2: CO2 analysis
Normal pCO2 level: 35-45mmHg
Below 35mmHg or 4.7Kpa is alkalosis
Above 45mmHg or 6Kpa is acidosis
Prepared by NLERT Feb,2015
28. Step 3: HCO3 analysis
Step 3: HCO3 analysis
Step 3: HCO3 analysis
Step 3: HCO3 analysis
Normal HCO3 level is 22
Normal HCO3 level is 22
Normal HCO3 level is 22
Normal HCO3 level is 22-
-
-
-26 mEq/L
26 mEq/L
26 mEq/L
26 mEq/L
Below 22 mEq/L is acidosis
Below 22 mEq/L is acidosis
Below 22 mEq/L is acidosis
Below 22 mEq/L is acidosis
Above 26 mEq/L is alkalosis
Above 26 mEq/L is alkalosis
Above 26 mEq/L is alkalosis
Above 26 mEq/L is alkalosis
Prepared by NLERT Feb,2015
29. Step 4: Match CO2 and HCO3
Step 4: Match CO2 and HCO3
Step 4: Match CO2 and HCO3
Step 4: Match CO2 and HCO3
with the pH level
with the pH level
with the pH level
with the pH level
Match either PCO2 and HCO3 with pH level to
determine the primary cause of acid-base
disorder
If primary acid base disorder caused by
respiratory, CO2 level is opposite to pH level
If Primary acid base disorder caused by
metabolic, HCO3 level is equal to pH level
Prepared by NLERT Feb,2015
31. Mixed acid base disorder
That means more than one primary acid base
disturbance at the same time. (particularly in
critically illness).
For example
COPD patient who develops shock and lactic acidosis
pH↓ CO2 ↑HCO3↓and matched with primary cause
= Mixed acidosis
Prepared by NLERT Feb,2015
32. Step 5: Does CO2 or HCO3 go to the
opposite direction of pH
(determinate the compensation)
Either CO2 or HCO3 go to the opposite
direction of pH, that means
compensation in progress.
Prepared by NLERT Feb,2015
34. Respiratory system
Respiratory system
Respiratory system
Respiratory system
compensation
compensation
compensation
compensation
Respiratory system balances pH by ↑ or ↓ RR to
manipulating the CO2 level.
Fast and deep breathing “blows off” CO2 in
primary metabolic acidosis.
Slow and shallow breathing “retains” CO2 in
primary metabolic alkalosis.
The process is fast.
Prepared by NLERT Feb,2015
35. Renal System
Renal System
Renal System
Renal System
Compensation
Compensation
Compensation
Compensation
Primary respiratory alkalosis:
Primary respiratory alkalosis:
Primary respiratory alkalosis:
Primary respiratory alkalosis:
Kidney
Kidney
Kidney
Kidney▶▶▶
▶▶▶
▶▶▶
▶▶▶Excreting more HCO3
Excreting more HCO3
Excreting more HCO3
Excreting more HCO3-
-
-
- in
in
in
in
urine and retaining more H+
urine and retaining more H+
urine and retaining more H+
urine and retaining more H+
Primary respiratory acidosis:
Primary respiratory acidosis:
Primary respiratory acidosis:
Primary respiratory acidosis:
Kidney
Kidney
Kidney
Kidney▶▶▶
▶▶▶
▶▶▶
▶▶▶Excreting more H+ in urine
Excreting more H+ in urine
Excreting more H+ in urine
Excreting more H+ in urine
and retaining more HCO3
and retaining more HCO3
and retaining more HCO3
and retaining more HCO3-
-
-
-
The process is slow
The process is slow
The process is slow
The process is slow
but more powerful.
but more powerful.
but more powerful.
but more powerful.
Prepared by NLERT Feb,2015
36. Partial/Complete
Partial/Complete
Partial/Complete
Partial/Complete
compensation
compensation
compensation
compensation
Compensation may not always be
Compensation may not always be
Compensation may not always be
Compensation may not always be
complete and time consuming.
complete and time consuming.
complete and time consuming.
complete and time consuming.
If pH remains abnormal, it is partial
If pH remains abnormal, it is partial
If pH remains abnormal, it is partial
If pH remains abnormal, it is partial
compensation.
compensation.
compensation.
compensation.
If pH returns to normal range, the
If pH returns to normal range, the
If pH returns to normal range, the
If pH returns to normal range, the
compensation is complete.
compensation is complete.
compensation is complete.
compensation is complete.
Note
Note
Note
Note
Nothing to do = no compensation
Nothing to do = no compensation
Nothing to do = no compensation
Nothing to do = no compensation
Prepared by NLERT Feb,2015
37. Step 6: Analysis pO2 and O2
Step 6: Analysis pO2 and O2
Step 6: Analysis pO2 and O2
Step 6: Analysis pO2 and O2
saturation
saturation
saturation
saturation
Evaluate the PaO2 and O2 saturation. If
they are below normal there is evidence of
hypoxemia.
PaO2 (80-100mmHg or 10.3-13.3 kPa).
SaO2 (95~100%).
Prepared by NLERT Feb,2015
38. ABG quiz
1. Metabolic Acidosis has a low level of
what?
A: PO2
B: CO2
C: Compensated Respiratory Acidosis
D: Bicarbonate (HCO3)
Prepared by NLERT Feb,2015
40. 3.Decrease HCO3 and decrease pH may
causes what?
A: Uncompensated
B: Increase arterial PO2
C: It will lower the pH
D: Metabolic Acidosis
Prepared by NLERT Feb,2015
41. 4.The primary drive to breath comes from
the patient?
A: Acidosis
B: Bicarbonate (HCO3)
C: Uncompensated Metabolic Acidosis
D: CO2 level
Prepared by NLERT Feb,2015
42. 5. A high CO2 will impact the pH?
A: Lower the pH value (acidosis)
B: Bicarbonate (HCO3)
C: Increase arterial PO2
D: Metabolic Acidosis
Prepared by NLERT Feb,2015
43. 6. pH = 7.56 CO2 = 50 HCO3 = 38
A: Normal
B: Respiratory alkalosis without
compensation
C: Partly compensated metabolic alkalosis
D: Metabolic alkalosis
Prepared by NLERT Feb,2015
44. 7. pH = 6.96 CO2 = 71 HCO3 = 16
A: Metabolic alkalosis
B: Normal
C: Mixed acidosis
D: Compensated acidosis
Prepared by NLERT Feb,2015
45. 8. Interpret this blood gas
pH=7.50 PaCO2=60 HCO3=38
A: Combined acidosis
B: Partly compensated metabolic Alkalosis
C: Bicarbonate (HCO3)
D: Increase ventilation
Prepared by NLERT Feb,2015
53. 16. pH = 7.48 CO2 = 19 HCO3 = 14
A: Normal
B: Respiratory acidosis
C: Compensated metabolic acidosis
D: Partly compensated respiratory
alkalosis
Prepared by NLERT Feb,2015
54. Reference
Reference
Reference
Reference
Irwin RS Rippe JM 2011 Irwin and Rippe’s Intensive
Care Medicine (7th edition) Lippincott Williams Wilkins:
Philadelphia
Domino FJ 2013 The 5-Minute Clinical Consult 21st
Edition Lippincott Williams Wilkins: Philadelphia
Nettina SM 2010 Lippincott Manual of Nursing Practice
(9th edition). Lippincott Williams Wilkins: Philadelphia
Carpenito-Moyet LJ 2009 Nursing Care Plans and
Documentation: Nursing Diagnosis and Collaborative
Problems (5th Edition). Lippincott Williams Wilkins:
Philadelphia
Prepared by NLERT Feb,2015
