Respiratory Part 2

Respiratory part 2

Chronic respiratory acidosis: • • • • • •

Emphysema SOB Pink puffer Pursed lips Hyperinflated Wheeze

• • • • • • • •

Obstructive COPD Blue boater Confused Hypoinflated Wheeze Warm full veins Peripheral oedema

Chronic respiratory acidosis: • • • • •

Pink puffer Respiratory drive high Hypo oxygen Hypo CO2 Desaturates on exercise.

• Type 1 respiratory failure

• • • • •

Blue bloater Respiratory drive low Hypo oxygen Hyper CO2. Right side heart failure (Oedema) • Type 2 respiratory failure.

Chronic pulmonary disease • Type 1 – could be from pulmonary oedema, pulmonary fibrosis, lobar pneumonia, “shunting”. • Type 2 – could be from bronchopneumonia, chronic bronchitis.

Typical chronic respiratory acidosis: • • • • • •

Life long heavy smoker. (Alpha 1 anti trypsin deficiency) Male Urban dweller. Low social class. Air pollution.

Pursed lips breathing

Bronchiectasis – dilation of the bronchi • • • • •

Congenital or genetic – cystic fibrosis. Childhood infection – whooping cough. Bronchial obstruction – inhaled Allergic disease aspergillosis Autoimmune disease – primary biliary cirrhosis.

Bronchiectasis

Respiratory alkalosis • • • •

Hysteria Mechanical over ventilation Raised intracranial pressure, Hypoxia.

• Acute condition – no renal compensation possible.

How to interpret blood gas results • Look at pH, is it acidosis, normal or alkalosis? • If pH is low, look at pCO2, if increased then respiratory, look at bicarbonate, if decreased then metabolic disease. • If pH is high, look at pCO2, if decreased then respiratory, look at bicarbonate, if increased then metabolic disease. • Look for compensation, is it partial or full?

25 year-old woman with history of mental illness, suicide tries Rapid breathing • Blood pH 7.58 (7.35-7.45) • pCO2 26 mm Hg (35-45) • Bicarbonate 18 mmol/L (22-30) • pO2 115 mm Hg (80-100) • Acid base diagnosis? What next?

Mixed acid base disorders • Patient may have more than one acid base disease. • Both could give acidosis or alkalosis – a potentially lethal mix. • They could offset each other.

Mixed acid base diseases examples: • COPD with thiazide induced K depletion • Over ventilation with prolonged nasogastric suction • Salicylate poisoning after a hour or so. Limits to compensation: • pCO2 12-55 mm Hg- takes seconds to happen • Bicarbonate 5-50 mmol/L – takes days.

70 year old man collapsed, cyanosed. Blood pH 6.9 (7.35-7.45) pCO2 60 mm Hg (35-45) pO2 50 mm Hg (80-100) Bicarbonate 15 mmol/L (22-30) Comment on his acid base status.

80 year old man, DM II, chest pain, breathless, cyanosed Blood pH 7.6 (7.35-7.45) pCO2 15 mm Hg (35-45) pO2 50 mm Hg (80-100) bicarbonate 40 mmol/L (22-30) {infused} Comment on his acid base status.

Oxygen transport diseases. • Blood O2 2% dissolved, 98% on haemoglobin Hb • Oxygen saturation: % Hb as oxyhaemoglobin. Pulse oximetry Affinity of O2 for Hb depends on pH and DPG (diphosphoglycerate) Delivery depends on pO2, Hb, Hb function, cardiac output and peripheral perfusion (vasodilation contraction). • Plasma lactate for perfusion efficiency.

Stimulation to ventilation • Increased pCO2 • Fall in pH (rise in H+) • Decreased pO2 ( below 60 mm Hg).

Respiratory failure: • Type 1: low pO2 and normal pCO2. Pulmonary edema, pulmonary fibrosis, lobar pneumonia, “shunting”. • Type 2: low pO2 and raised pCO2. Bronchial pneumonia, chronic bronchitis.

Some pulmonary diseases of laboratory interest: • • • • •

Asthma Interstitial lung diseases Pleural diseases Pulmonary embolus/infarct Lung cancer.

Asthma: • • • •

Narrowing of bronchi. Children 5%, adults 2%. Possible occupational. Possible exercise in cold triggers it (Lillehammer Olympics, Joyner-Kersey) • Infections. • Drugs: aspirin, beta blockers.

Asthma symptoms: • • • • • •

Short of breath Wheeze Worst in early morning Sometimes seasonal Cough. May be acute or chronic.

Asthma laboratory work: • • • •

Air flow obstruction > 15%. Arterial blood gases Oesinophilia if caused by extrinsic factors. Skin tests positive and raised IgE in extrinsic. • Aminophylline drug used in treatment. Caffeine in infants. May be measured to prevent toxicity.

Asthma