- 15-20 (average 20)/min
- For unknown reason (and no data cited), most textbooks record the normal rate as 12-18/mins
Tachypnea = RR >25/min
Bradypnea = RR <10/minutes
Abnormal breathing patterns
- Enhanced sens to CO2: causes hyperventilation excessively until the Co2 level drops so low that apnea happens, then Co2 builds up again to stimulate hyperventilation again
- Circulatory delay between lungs and arteries: Co2 level in alveoli and in systemic arteries (that reach medulla) is out of sync. This delay causes waxing & waning of the tidal volume. This happens eg in CHF.
- Expiration against closed glottis producing low-medium pitch voice
- Indicates resp.muscle fatigue
- Pathogenesis: grunting resp slows down expiration, so more time for gases exchange.
Chest and abdominal mvements during respiration
- Normall in sync (chest moves out, abdomen moves out during inspiration and vice versa)
– During inspiration, diaphragm flattens downwards, therefore pushing the abdomen outwards. In expiration, diaphragm domes upwards, pulling the abdomen inwards.
- Out of sync
- During expiration, normal smooth inward abdominal movement is interrupted by sudden outward movement
- Seen in COPD, when the strong action of accessory muscles push the diahragm temporarily downward during expiration and therefore abdomen moves outwards suddenly.
- During inspiration, abdomen moves inwards (instead of outwards) and during expiration, abdomen moves outwards (instead of inwards)
- Pathogenesis: during inspiration, the outward movement of chest wall drags the diaphragm upwards, therefore abdomen moves inwards
- Seen in patients with diaphragmatic weakness.
- Breathlessness when lying down but relieved in upright position
- Most important in CHF
– Due to decreased lung compliance and redistribution of venous outflow to RV on supine position, but not entirely due to this.
– Other lung diseases eg IPF do not present with orthopnea
– Orthopnea correlates poorly with pulmonary artery pressure
– The fact that it can be relieved by elevation of head alone
- Breathlessness when lying on one side
- Seen in:
– Unilateral lung disease: lying on good side improves oxygenation due to increase perfusion
– CHF: lying on right side improves breathing, maybe due to left lung atelectasis from cardiomegaly
– Endobronchial tumour: lying on affected side will cause obstruction and wheezing
- Breathlessness when iin upright position but relieved in prone position
- Seen in
– Intracardiac shunt eg PE in a patient with ASD
– Intrapulmonary shunt eg in hepatopulmonary syndrome
Steven Mcgee. Evidence Based Physical Diagnosis Pg 187-202