Respiratory Acidosis
Download
Report
Transcript Respiratory Acidosis
Arash Safaie, MD
Emergency Physician
Basic Concepts
pH
↓7.36: Acidemia
↑7.44: Alkalemia
Physiologic Buffers
Bicarbonate
Carbonic Acid Systems (RBCs)
Phosphate Buffers (Bone)
Useful Knowledge
ABG vs. VBG
VBG
pH: 0.03↓
PCO2: 6.6↑
HCO3: 1.4↑
Role of Temperature
Tempe
rature
(°C)
pH
Paco2
(mm
Hg)
Pao2
(mm
Hg)
20
7.65
19
27
30
7.50
30
51
35
7.43
37
70
37
7.40
40
80
39
7.37
44
91
Respiratory Acidosis
Acute
Intracellular Buffering
CO2 Narcosis
↑PCO2: 10 ↑HCO3: 1
↑PCO2: 10 ↓pH: 0.08
Chronic
Beyond 6-12h starts 5d completes
Hypochloremia
↑PCO2: 10 ↑HCO3: 4
↑PCO2: 10 ↓pH: 0.03
Respiratory Alkalosis
Acute
Intracellular Buffering
↓PCO2: 10 ↓HCO3: 2
↓PCO2: 10 ↑pH: 0.08
Chronic
Beyond 6-36h starts 14d completes
Hyperchloremia
↓PCO2: 10 ↓HCO3: 3.5
↓PCO2: 10 ↑pH: 0.03
Pregnancy & Childhood
Pregnancy
pH: 7.46-7.50
PaCO2: 31-35
HCO3: 18-22
Childhood (7-19y)
PaCO2: 37
Metabolic Acidosis
Compensation
↓HCO3: 1 ↓PCO2: 1.2
PCO2: (1.5 x HCo3) + 8
12-24h for Max. Respiratory Response
Compensation Limit PCO2: 10-15
Normal AG
Urine AG: (Urine Na + Urine K) – Urine Cl
Positive Urine AG: Altered Urinary Acidification
Negative Urine AG: GI Loss
Role of NaHCO3 in Rx
Anion Gap & ΔGap
AG: Na – (Cl + HCO3)
> 15 High
< 3 Low
ΔG: (AG – 12) – (24 – HCO3)
>+6: concurrent Metabolic Alkalosis or Respiratory
Acidosis
<-6: concurrent Normal AG Metabolic Acidosis or
Respiratory Alkalosis
Metabolic Alkalosis
Compensation
↑HCO3: 1 ↓PCO2: 1.2
Compensation Limit PCO2: 55-75
Saline Responsiveness
Saline-Responsive: Urine Cl <10
Saline-Resistant: Urine Cl >10
Rx
Saline-Responsive: NaCl + KCl
Severe: IV Mineral Acids
Edematous: Acetazolamide, Dialysis
Saline-Resistant: KCl + Mineralocorticoid Antagonist
1
pH:
PCO2:
HCO3:
Na:
Cl:
7.37
50
28
139
102
2
pH:
PCO2:
HCO3:
Na:
Cl:
7.44
46
34
140
100
3
pH:
PCO2:
HCO3:
Na:
Cl:
7.35
28
14
140
110
4
pH:
PCO2:
HCO3:
Na:
Cl:
7.32
50
25
140
110
5
pH:
PCO2:
HCO3:
Na:
Cl:
7.43
30
22
140
108
6
pH:
PCO2:
HCO3:
Na:
Cl:
7.30
40
20
140
110
7
pH:
PCO2:
HCO3:
Na:
Cl:
7.37
16
4
140
96
8
pH:
PCO2:
HCO3:
Na:
Cl:
7.30
16
4
140
106
9
pH:
PCO2:
HCO3:
Na:
Cl:
7.30
28
14
140
111
10
pH:
PCO2:
HCO3:
Na:
Cl:
7.42
50
29
140
105