Respiratory Rate and Breathing patterns

Normal RR

  • 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

a.png

** Pathogenesis:

  • 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.

Grunting respirations

  • 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

i) Asynchronous

  • 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.

ii) Paradoxical

  • 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.

Photo Jan 20, 10 08 52 PM

Orthopnea

  • Breathlessness when lying down but relieved in upright position
  • Most important in CHF
  • Pathogenesis:
    – 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

Trepopnea

  • 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

Platypnea

  • 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

Reference

Steven Mcgee. Evidence Based Physical Diagnosis Pg 187-202

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