Download MBBS ABG and Acid Base Disorders Lecture PPT

Applications of ABG

To document respiratory failure and assess its severity.

--- Content provided by FirstRanker.com ---

To monitor patients on ventilators and assist in

weaning.

To assess acid base imbalance in critical illness.

--- Content provided by FirstRanker.com ---

To assess response to therapeutic interventions and

mechanical ventilation
ABG EQUIPMENT

--- Content provided by FirstRanker.com ---

Blood gas analyzers use electrodes to determine pH,

partial pressure of carbon dioxide and partial pressure of

--- Content provided by FirstRanker.com ---

oxygen in the blood.

It consist of three electrodes measuring pH, pCO2 and pO2

at 37 degree

--- Content provided by FirstRanker.com ---

It may also measure electrolytes like sodium, potassium

and chloride.

--- Content provided by FirstRanker.com ---

From these outputs, internal computers calculate oxygen

saturation, base excess and bicarbonate level.

--- Content provided by FirstRanker.com ---

Case Study

1. Sheela aged 19 years brought to casuality at 11 AM with

dizziness, tingling of fingers, sweating, breathing heavily and

--- Content provided by FirstRanker.com ---

nausea. O/E: Hyperventilation, carpopedal spasm was found.

Laboratory data:
pH

--- Content provided by FirstRanker.com ---

7.55

Pco2

--- Content provided by FirstRanker.com ---

20 mm Hg

HCO3

24 mmoles/l

--- Content provided by FirstRanker.com ---

1. What kind of acid-base disorder is this girl suffering from?

Explain.

--- Content provided by FirstRanker.com ---

2. What are the common causes of this kind of disorder?
3. Give the compensatory mechanism available in the body to

correct this sort of acid-base imbalance.

--- Content provided by FirstRanker.com ---

1. Respiratory alkalosis (uncompensated)
Tingling of fingers and carpopedal spasm is due to

reduction in ionized calcium caused by increased

--- Content provided by FirstRanker.com ---

binding of calcium to albumin in alkaline pH of ECF.

2. Common cause of respiratory alkalosis is functional

hyperventilation due to anxiety disorders.

--- Content provided by FirstRanker.com ---

It also occurs in cases where the respiratory center in

medulla is over stimulated as in encephalitis,

--- Content provided by FirstRanker.com ---

intracranial surgery, salicylate poisoning and chronic

liver disease
3. In respiratory alkalosis, there is loss of CO2 leading to

--- Content provided by FirstRanker.com ---

decrease in pCO2 and increase in bicarbonate to

carbonic acid ratio.

In an attempt to return the pH towards normal, kidney

--- Content provided by FirstRanker.com ---

excrete more bicarbonate in urine so that bicarbonate

-carbonic acid ratio is brought back to normal
2. Ramakrishnan, 60 years old, a known smoker

--- Content provided by FirstRanker.com ---

attended casuality with exacerbation of bronchial

asthma. The acid base analysis report is given below.

--- Content provided by FirstRanker.com ---

Give your interpretation.

Laboratory data:
pH

--- Content provided by FirstRanker.com ---

7.04

Pco2

90 mm Hg

--- Content provided by FirstRanker.com ---

HCO3

24 meq/L
Respiratory acidosis

--- Content provided by FirstRanker.com ---

Asthma attack are characterized by episodes of airway

obstruction leading to retention of CO2, leading to

increase pCO2,decreased bicarbonate to carbonic acid

--- Content provided by FirstRanker.com ---

ratio.

Renal compensatory mechanisms tend to retain

--- Content provided by FirstRanker.com ---

bicarbonate in the blood which in turn help to raise the

bicarbonate-carbonic acid in order to attain 20:1 ratio so

that normal pH is restored.

--- Content provided by FirstRanker.com ---

Generally respiratory acidosis is caused by disorders that

interfere with respiratory activity- pneumonia, asthma,

--- Content provided by FirstRanker.com ---

pulmonary edema,COPD

Morphine and barbiturate poisoning cause of depression

of respiratory centre leading to respiratory acidosis.

--- Content provided by FirstRanker.com ---

A woman complaining of intractable vomiting suspected of

suffering from pyloric stenosis receiving treatment showed

following acid base data on day 1 and day 2.

--- Content provided by FirstRanker.com ---

Laboratory data on day 1:
pH

7.6

--- Content provided by FirstRanker.com ---

pCO2

40 mm Hg

--- Content provided by FirstRanker.com ---

HCO3

35 meq/L

Laboratory data on data 2 :

--- Content provided by FirstRanker.com ---

pH

7.55

pCO2

--- Content provided by FirstRanker.com ---

45 mm Hg

HCO3

--- Content provided by FirstRanker.com ---

28 meq/L
Kumaran,58 year old peon in a private firm has been suffering from DM for the past 20

years. He was taking irregular treatment for DM. One day he was brought to the

--- Content provided by FirstRanker.com ---

casuality in a stuperosed state. O/E: Fruity odor in breath, Kussmaul's type of breathing

+

Laboratory data

--- Content provided by FirstRanker.com ---

Urine Rothera's Test ? Positive
Plasma Glucose- 450 mg/dl
ABG analysis report
pH

--- Content provided by FirstRanker.com ---

7.2

pCO2

40 mm Hg

--- Content provided by FirstRanker.com ---

HCO3

15 meq/L

--- Content provided by FirstRanker.com ---

Na



140 mmol/L

--- Content provided by FirstRanker.com ---

K

4 mmol/L

--- Content provided by FirstRanker.com ---

Cl

102 mmol/L

1. What is the problem diagnosis? Explain.

--- Content provided by FirstRanker.com ---

2. Calculate the anion gap from given laboratory data?
3. What is the value of normal anion gap?