11

(4) Respiratory alkalosis(4) Respiratory alkalosis

1) Concept1) Concept

Respiratory alkalosis is defined as a Respiratory alkalosis is defined as a primary decrease in [Hprimary decrease in [H22COCO33] ([CO] ([CO22], ], PaCOPaCO22) in plasma) in plasma

HypocapniaHypocapnia

The secondary change is the decrease The secondary change is the decrease of [HCOof [HCO33¯̄ ] in plasma due to the renal ] in plasma due to the renal compensation. compensation.

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2) Causes and Pathogenesis2) Causes and Pathogenesis

Increased alveolar ventilation Increased alveolar ventilation Hypoxia due to high altitudeHypoxia due to high altitudeHysteriaHysteriaFever Fever Central nervous diseases Central nervous diseases Gram-negative septicemiaGram-negative septicemiaSalicylate intoxicationSalicylate intoxication

The basic reason of hyperventilation is the The basic reason of hyperventilation is the stimulation of respiratory center.stimulation of respiratory center.

Mis-operation of mechanical ventilatorMis-operation of mechanical ventilator

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3) Compensation3) Compensation

The compensation of respiratory The compensation of respiratory alkalosis is in the opposite direction of the alkalosis is in the opposite direction of the compensation of respiratory acidosis.compensation of respiratory acidosis.

The main mechanisms are cellular The main mechanisms are cellular and renal compensationand renal compensation

(How about buffering system, respiration?)(How about buffering system, respiration?)

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(a)(a) Cellular compensation for acute Cellular compensation for acute typetype

a) a) HH++-K-K++ exchange exchange

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b)COb)CO22 moves out of the cells moves out of the cells

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(b)The renal compensation for (b)The renal compensation for chronic typechronic type

The renal compensation in respiratory The renal compensation in respiratory alkalosis is the same as the renal alkalosis is the same as the renal compensation in metabolic alkalosis.compensation in metabolic alkalosis.

It may take 3~5 days to reach the It may take 3~5 days to reach the maximal renal compensation.maximal renal compensation.

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Changes of laboratory parametersChanges of laboratory parameters

Primary decrease of [HPrimary decrease of [H22COCO33]:]:

PaCOPaCO2 2 ??

Secondary compensationSecondary compensation::

AB,SB,BB ???AB,SB,BB ???

AB ?? SBAB ?? SB

BE ?BE ?

pH ?pH ?

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Changes of laboratory parametersChanges of laboratory parameters

Primary decrease of [HPrimary decrease of [H22COCO33]:]:

PaCOPaCO2 2 decreasedecrease

Secondary compensationSecondary compensation::

AB,SB,BB decreaseAB,SB,BB decrease

AB < SBAB < SB

BE negative value increasesBE negative value increases

pH tends to increase.pH tends to increase.

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Predicted compensatory formula for Predicted compensatory formula for acute respiratory alkalosisacute respiratory alkalosis

ΔHCOΔHCO33-- = 0.2x ΔP = 0.2x ΔPaCOaCO22 ±± 2.5 2.5

HCOHCO33-- = 24+0.2x (P = 24+0.2x (PaCOaCO22 -40) -40)±± 2.5 2.5

Secondary compensation primary changeSecondary compensation primary change

Value measured > value predicted: with Value measured > value predicted: with metabolic alkalosis metabolic alkalosis

Value measured < value predicted: with Value measured < value predicted: with metabolic acidosismetabolic acidosis..

Maximal compensatory value up to:18 mmol/LMaximal compensatory value up to:18 mmol/L

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Predicted compensatory formula for Predicted compensatory formula for chronic respiratory alkalosischronic respiratory alkalosis

ΔHCOΔHCO33-- = 0.5x ΔP = 0.5x ΔPaCOaCO22 ±± 2.5 2.5

HCOHCO33-- = 24+0.5x (P = 24+0.5x (PaCOaCO22 -40) -40)±2.5±2.5Secondary compensation primary changeSecondary compensation primary change

Value measured > value predicted: with Value measured > value predicted: with metabolic alkalosis metabolic alkalosis

Value measured < value predicted: with Value measured < value predicted: with metabolic acidosismetabolic acidosis..

Maximal compensatory value up to:12 mmol/LMaximal compensatory value up to:12 mmol/L

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(3) Effects on the body(3) Effects on the body

  1) Effects on the central nervous system.1) Effects on the central nervous system.

2) Effects on metabolism2) Effects on metabolism

   （（ hypophosphatemiahypophosphatemia ））

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1) Effects on the central nervous 1) Effects on the central nervous systemsystem

((a) a) Excitability is increased.Excitability is increased. Manifestations are more severe than Manifestations are more severe than those of metabolic alkalosisthose of metabolic alkalosis..

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The reasons :The reasons :

(a) Hyperventilation (a) Hyperventilation leads to low [COleads to low [CO22] in ] in plasma and cerebral plasma and cerebral vasoconstriction, the vasoconstriction, the oxygen supply to the oxygen supply to the brain is decreased.brain is decreased.

(b) The left-shift of (b) The left-shift of oxygen-hemoglobin oxygen-hemoglobin dissociation curve leads dissociation curve leads to brain hypoxia.to brain hypoxia.

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Glutamic acidGlutamic acid

Glutamate decarboxylase

r-GABA, r-aminobutyric acid

r-GABA transminase

Succinic acid

Kreb’s cycle

(c) The production of GABA (gama aminobutyric (c) The production of GABA (gama aminobutyric acid, a inhibitory transmitter), is decreased due acid, a inhibitory transmitter), is decreased due to the activity of enzyme for the production is to the activity of enzyme for the production is reduced in alkalosis.reduced in alkalosis.

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2) 2) 低磷血症 低磷血症 hypophosphatemiahypophosphatemia

细胞内碱中毒使糖元分解增多细胞内碱中毒使糖元分解增多 ,, 在磷酸在磷酸化酶作用下形成葡萄糖化酶作用下形成葡萄糖 6-6- 磷酸盐等磷酸化磷酸盐等磷酸化合物增多合物增多 ,, 需用磷增多需用磷增多 , , 细胞外磷进入细胞细胞外磷进入细胞内内。。

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Treatment principleTreatment principle

For respiratory alkalosis:For respiratory alkalosis:

Let the patient inhale the air that is Let the patient inhale the air that is exhaled by himself (herself) with a “mask”.exhaled by himself (herself) with a “mask”.

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Thinking method of diagnosisThinking method of diagnosis

(1) via pH: acidosis or alkalosis ?(1) via pH: acidosis or alkalosis ?

compensatory or decompensatory ?compensatory or decompensatory ?

(2) via history: primary change(2) via history: primary change

metabolic or respiratory ?metabolic or respiratory ?

(3) via predicted compensatory value:(3) via predicted compensatory value:

simple or mixed ?simple or mixed ?

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Case discussionCase discussion

A 32-year-old male presented with vomiting of A 32-year-old male presented with vomiting of one week’s duration. On examination, he one week’s duration. On examination, he appeared dysphoria and had a supine blood appeared dysphoria and had a supine blood pressure of 90/60 mmHg and a pulse of pressure of 90/60 mmHg and a pulse of 116/min.116/min.

The laboratory results were:The laboratory results were:

Arterial blood: pH=7.55 PaCOArterial blood: pH=7.55 PaCO22=46 mmHg=46 mmHg

PaOPaO22=90mmHg =90mmHg

[HCO[HCO33--]=38 mmol/L.]=38 mmol/L.

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See pHSee pH

See primary historySee primary history

ΔΔPaCOPaCO22=0.7x=0.7xΔΔHCOHCO33- - ±± 5 5

= 0.7x 14 = 0.7x 14 ±± 5 5

= 10 = 10 ±± 5 (5~15)mmHg 5 (5~15)mmHg

Predicted 40+ 5~15=Predicted 40+ 5~15=45~55,45~55,

measure: 46, measure: 46,

Decompensatory metabolic alkalosis. Decompensatory metabolic alkalosis.

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Case discussionCase discussion

A 58-year-old man with pulmonary heart A 58-year-old man with pulmonary heart disease had 3 days of diarrhea. disease had 3 days of diarrhea.

pH=7.12, PaCOpH=7.12, PaCO22= 85 mmHg,HCO= 85 mmHg,HCO3 3 -- =26 mmol/L =26 mmol/L

NaNa++=137 mmol/L, Cl=137 mmol/L, Cl-- =85 mmol/L =85 mmol/L

ΔΔHCOHCO3 3 -- =0.4 x=0.4 xΔΔPaCOPaCO22 ±± 3 = 18 3 = 18 ±± 3 3

Predicted 24+18 Predicted 24+18 ±± 3 = 39~45 3 = 39~45

(1) via pH: decompensatory acidosis (1) via pH: decompensatory acidosis (2) via history: primary change: respiratory (2) via history: primary change: respiratory (3) via predicted compensatory value: mixed(3) via predicted compensatory value: mixedRespiratory acidosis + metabolic acidosis Respiratory acidosis + metabolic acidosis (AG??) (AG??)

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A patient with diabetes:A patient with diabetes:

Measured:Measured:pH = 7.32pH = 7.32PaCOPaCO2 2 = 30mmHg= 30mmHg

Checked:Checked:Chronic metabolic Chronic metabolic

acidosisacidosisHCOHCO33- - = 16 mmol/L= 16 mmol/LBE = -9 mmil/LBE = -9 mmil/L

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A patient with CHDA patient with CHD

Measured:Measured:

pH=7.22pH=7.22

PaCOPaCO2 2 = 50mmHg= 50mmHg

Checked:Checked:

Respiratory Respiratory acidosis+metabolic acidosis+metabolic acidosisacidosis

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Section 3. Mixed types of acid-base Section 3. Mixed types of acid-base disturbancesdisturbances

（（ 11 ） ） DoubleDouble 双重性 双重性 acid-base disordersacid-base disorders

11 ）呼吸性）呼吸性 ++ 代谢性混合型代谢性混合型 呼酸呼酸 ++ 代酸代酸 呼酸呼酸 ++ 代碱代碱 呼碱呼碱 ++ 代酸代酸 呼碱呼碱 ++ 代碱代碱

22 ）代谢混合型）代谢混合型 代酸代酸 ++ 代碱代碱 高高 AGAG 代酸代酸 ++ 高高 ClCl 代酸代酸

3) 3) 呼吸混合型？？呼吸混合型？？

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Case discussionCase discussion A 45-year-old man had chronic cough for A 45-year-old man had chronic cough for 20 years. He had a shortness of breath, 20 years. He had a shortness of breath, orthopnea with edematous ankles for 1 month. orthopnea with edematous ankles for 1 month. The laboratory findings were:The laboratory findings were: pH = 7.26 PaOpH = 7.26 PaO22=55 mmHg =55 mmHg PaCOPaCO22=60 mmHg AB = 22 mmol/L=60 mmHg AB = 22 mmol/L

See pH: Decompensated acidosisSee pH: Decompensated acidosisSee history: Respiratory disorderSee history: Respiratory disorderCalculate:Calculate:

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Predicted: ΔHCOPredicted: ΔHCO33-- = 0.4x ΔP = 0.4x ΔPaCOaCO22 ±± 3 3

HCOHCO33-- = 24+0.4x 20 = 24+0.4x 20 ±± 3=29~35 3=29~35

Measured: 22Measured: 22

Respiratory acidosis + metabolic acidosisRespiratory acidosis + metabolic acidosis

pH??pH??HCOHCO33-- ?? ??

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Respiratory alkalosis + metabolic acidosis Respiratory alkalosis + metabolic acidosis

A patient with salicylic acid poisoning A patient with salicylic acid poisoning

(stimulating respiratory center)(stimulating respiratory center)

pH= 7.45pH= 7.45

PaCOPaCO22=20mmHg=20mmHg

HCOHCO33--=13 mmol/L=13 mmol/L

ΔHCOΔHCO33-- = 0.2x ΔP = 0.2x ΔPaCOaCO22 ±± 2.5 2.5

Predicted HCOPredicted HCO33-- = 24 - 4 = 20 = 24 - 4 = 20 ±± 2.5 2.5

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In metabolic acidosis + metabolic alkalosis In metabolic acidosis + metabolic alkalosis

pH is in normal range,pH is in normal range,

[HCO[HCO33--] is in normal range.] is in normal range.

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(2)(2) TripleTriple 三重性 三重性 acid-base disordersacid-base disorders

A 62-year-old woman with chronic A 62-year-old woman with chronic bronchitis and emphysema for more than bronchitis and emphysema for more than 15 years. was admitted to the hospital in a 15 years. was admitted to the hospital in a confused state. Her temperature was confused state. Her temperature was 38.538.5 .℃.℃ The laboratory data:The laboratory data: pH = 7.27 PaCOpH = 7.27 PaCO22=65 mmHg=65 mmHg AB=28mmol/LAB=28mmol/L

2929

Respiratory acidosis + metabolic acidosisRespiratory acidosis + metabolic acidosis

Predicted: ΔHCOPredicted: ΔHCO33-- = 0.4x ΔP = 0.4x ΔPaCOaCO22 ±± 3 3

HCOHCO33-- = 24+0.4x 25 = 24+0.4x 25 ±± 3=31~37 3=31~37

Measured:28Measured:28

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The next day she presented with The next day she presented with severe vomiting . The laboratory finding:severe vomiting . The laboratory finding:

In venous blood: In venous blood:

[K[K++]] = 3.3 mmol/L [Cl= 3.3 mmol/L [Cl-- ]= 54 mmol/L ]= 54 mmol/L

pH= 7.4 AB=52 mmol/L pH= 7.4 AB=52 mmol/L

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Respiratory acidosis + metabolic acidosisRespiratory acidosis + metabolic acidosis

+ + metabolic alkalosismetabolic alkalosis

(causes?)(causes?)

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A patient with pulmonary heart A patient with pulmonary heart disease treated by diuretics.disease treated by diuretics.

pH= 7.43, PaCOpH= 7.43, PaCO22=61mmHg, HCO=61mmHg, HCO33--=38 mmol/L=38 mmol/L

Na+=140mmol/L, ClNa+=140mmol/L, Cl-- = 74 mmol/L, = 74 mmol/L,

KK++ = 3.5mmol/L = 3.5mmol/L Predicted[HCOPredicted[HCO33--]=32.4]=32.4 AG=140-(74+38)=28AG=140-(74+38)=28Respiratory acidosis+metabolic Respiratory acidosis+metabolic

alkalosis+metabolic acidosis with increased AGalkalosis+metabolic acidosis with increased AG