Expansion
Rate, accessory muscles, recession, position and the ability to speak
Expansion
Signs of increased work of breathing
- Tachypnoea, and the inability to complete sentences in one breath
- Accessory muscle use: sternocleidomastoid, scalenes, and the tripod position
- Intercostal, subcostal and tracheal tug recession, particularly in children
- Nasal flaring and grunting in infants
- Pursed lip breathing, which generates positive end expiratory pressure in obstructive disease
- Paradoxical abdominal movement, indicating diaphragmatic fatigue
- Inability to lie flat, agitation, sweating
Signs of failure and exhaustion, which are more sinister than distress
- Falling respiratory rate in a patient who was tachypnoeic
- Silent chest
- Drowsiness and confusion, from hypercapnia
- Bradycardia and hypotension
- Cyanosis, which is late and unreliable, requiring about 5 g/dl of deoxygenated haemoglobin and therefore appearing early in polycythaemia and late in anaemia
- Asterixis, bounding pulse and headache in carbon dioxide retention
Objective measures: oxygen saturations with the inspired oxygen concentration recorded alongside, arterial blood gas for carbon dioxide and pH, and peak flow compared with the predicted or best value in asthma.
A normal saturation on high flow oxygen is not reassurance; the amount of oxygen required is as important as the number achieved.