Respiratory Acidosis and Alkalosis Flashcards

1
Q

Normal Arterial blood gas

A
HCO3- = 24
PaCO2= 40
PaO2= 95
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2
Q

Alveolar gas normal

A
PaCO2= 36
PaO2= 105
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3
Q

Venous blood gas normal

A
PvCO2= 50
PvO2= 30-40
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4
Q

Respiratory acidosis

A

Build up of CO2 in blood
pH more acidic
Brough about by some form of breathing difficulty

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5
Q

Resp acidosis MOA

A

CO2 accumulates if lungs don’t dispel it through alveolar ventilation

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6
Q

Alveolar hypoventilation

A

Increased PCO2- hypercapnia

–> decrease in blood pH

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7
Q

Resp acidosis main causes

A

Hypoventilation due to drugs that suppress breathing
Diseases of airway
Diseases of chest (scoliosis)
Diseases that affect nerves + muscles that drive lungs to inflate or deflate
Severe obesity

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8
Q

Degree of change in blood pH depends on

A

Body’s ability to buffer the excess CO2

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9
Q

Henderson-Hasselbach equation

A

pH= 6.1 + log [(HCO3-)/0.03 x pCO2]

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10
Q

pH

A

log(1/[H+])

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11
Q

pKa

A

6.1 at body temp

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12
Q

Resp acidosis chemicals

A
High PaCO2 (>40mmHg)
Slightly raised HCO3- (>24mmHg)
Ratio of [HCO3-]/pCO2 decreases -->pH also decreases
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13
Q

Resp Acidosis symptoms explanation

A

CO2 lipid soluble gas- diffuse across BBB
HCO3- = ion, can’t enter CSF
–> CSF less buffered than blood so pH changes faster in response to CO2

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14
Q

Resp acidosis symptoms

A
Headache
Drowsiness
Lethargy
Anxiety
Sleepiness
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15
Q

Resp acidosis Signs

A
Slow breathing
Gait disturbance
Blunted deep tendon reflexes
Disorientation
Tremor
Myoclenic jerks
Papilloedema
Tachycardia
BP drop
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16
Q

Resp Acidosis Diagnosis

A

pH<7.35
pCO2 >45mmHg
Blood sample for pH
ABG

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17
Q

Resp Acidosis Treatment

A

Aimed at underlying lung disease

–> bronchodilators, ventilation, O2, smoking cessation

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18
Q

Acute Resp acidosis findings

A

pCO2 > 6.3kPa/47mmHg

pH<7.35

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19
Q

Acute resp acidosis

A

When an abrupt failure of ventilation occurs

20
Q

Acute resp acidosis Causes

A

Depression of central resp. centre by cerebral disease or drugs
Inability to ventilate adequately due to neuromuscular disease
Airway obstruction related to asthma or COPD

21
Q

Chronic Resp Acidosis findings

A

pCO2 > 6.3kPa/47mmHg

pH normal or near normal

22
Q

Chronic Resp Acidosis MOA

A

pH nearly normal because renal compensation–> produced a highly elevated serum bicarbonate

23
Q

Chronic resp acidosis Causes

A

Hypoventilation COPD
Obesity hypoventilation syndrome
Neuromuscular disorders
Severe restrictive ventilatory defects

24
Q

Metabolic compensation for Resp Acidosis

A

Kidneys generate + retain bicarbonate
Bicarb retention sometimes called “compensating metabolic alkalosis”
Maximum plasma HCO3- level reached this way is 45mmol/L

25
Q

Respiratory Alkalosis

A

Amount of CO2 in blood drops below normal
pH more alkaline
Usually due to hyperventilation

26
Q

Resp Alkalosis MOA

A

CO2 expelled too much
H+ and HCO3- ions in plasma react (via carbonic anhydrase) to make more CO2
Decrease in circulation H+ –> increased pH

27
Q

Acute Resp Alkalosis Symptoms

A
Dizziness
Lightheaded
Agitation
Confusion
Cramps
Tinging
28
Q

Acute Resp Alkalosis Signs

A
Muscle twitching
Hyperpnoea
Chest pain
Blurred vision
Spasms
Weakness
Seizures
29
Q

Chronic Resp Alkalosis Signs + symptoms

A

Asymptomatic

No distinctive signs

30
Q

Resp Alkalosis Main causes

A
Intracerebral haemorrhage
Meningitis
Stroke
Drug usage
Anxiety
Stress
Sepsis

Any lung disease that leads to shortness of breath

31
Q

Acute Resp Alkalosis

A

Rapid

Person may lose consciousness

32
Q

Chronic Resp Alkalosis

A

Asymptomatic due to metabolic compensation
Kidneys excrete more bicarbonate –> gives a metabolic acidosis to compete with resp alkalosis
Compensation complete in 7-10 days

33
Q

Resp Alkalosis body changes

A

Cerebral BV constriction
Impaired O2 delivery
Increase neuromuscular excitability
Hypokalaemia

34
Q

K in Chronic Resp Acidosis

A

Protons excreted in kidney
Potassium retained
Hyperkalaemia

35
Q

K in Chronic Resp Alkalosis

A

Protons retained in kidney
K excreted
Hypokalaemia

36
Q

Resp Alkalosis Diagnosis

A

pH > 7.44

pCO2 <35mmHg

37
Q

Resp Alkalosis Treatment

A
Treat underlying condition
Hyperventilation- breathe into paper bag
Pneumonia- antimicrobials
Drug overdose- Poisoning treatment
Mechanical ventilation if necessary
38
Q

Type 1 Resp Failure

A

Hypoxic
pO2 < 60mmHg
pCO2 normal or low
Most common

39
Q

Type 2 Resp Failure

A

Hypercapnic
pCO2 > 50mmHg
pO2 normal or low

40
Q

O2 and CO2 diffusion in lungs

A

CO2 diffuses in and out much faster as steeper conc. gradient between blood + alveoli
CO2 can be maintained at normal levels even with reduced ventilation

41
Q

Type 1 Resp failure examples

A

Pulmonary oedema
Pneumonia
Pulmonary haemorrhage

42
Q

Ventilation/perfusion mismatch

A

If lobe poorly ventilated, capillaries + arterioles constrict –> reduced blood flow

43
Q

Type 1 complications

A

If area of lung constricted then downstream alveoli hypoxic –> local capillaries constrict
–> even less O2 to affected region

44
Q

Anion gap

A

[Na+] - ([Cl-] + [HCO3-]) = 12 mEq/L

Measures amount of unmeasured anions

45
Q

High anion gap

A

Loss of plasma bicarbonate

  • -> elevated of anions like lactate
  • -> METABOLIC ACIDOSIS
46
Q

Normal anion gap but still unwell

A

GI loss of bicarbonate due to vom
Renal loss of bicarb due to renal damage

Bicarb low but chlorine high