Nursing Foundations · Oxygenation needs

Oxygenation Needs

Vesicular breath soundsdefinition

Normal, soft, low-pitched rustling sounds heard over most lung fields.

in simple words: Normal breathing sound.

Adventitious Breath Sounds

Sound	Character	Cause
Wheezes	High-pitched, continuous musical	Narrowed airways (asthma, bronchitis)
Rhonchi	Low-pitched, continuous snoring/rumbling	Secretions in larger airways
Gurgles (coarse crackles)	Loud, low-pitched, bubbling, intermittent	Air moving through fluid in airways

Hypoxia: Early vs Late Signs

Conscious patient – Restlessness, apprehension, agitation – early sign (sympathetic stimulation, cerebral hypoxia).
Unconscious patient – Tachycardia – earliest reliable sign (cannot observe behavioural changes).
Late sign – Cyanosis – appears only when hypoxia is advanced (desaturated haemoglobin).

Oxygenation Needs · Nursing Foundations

Oxygen Delivery Devices

Choosing the right device

Oxygen delivery devices vary in flow and precision. The Venturi mask gives a fixed, accurate FiO2; the nasal cannula gives an approximate, variable FiO2; the non-rebreather mask delivers the highest oxygen concentration for acute distress.

Comparison of Oxygen Devices

Device	FiO2	Key point
Nasal cannula	Approximate, variable	Low-flow; depends on respiratory rate and tidal volume
Venturi mask	Fixed, accurate	Most reliable for precise FiO2; uses colour-coded diluter jets
Non-rebreather mask	Up to 95%	Initial choice for acute respiratory distress needing highest O2

Oxygen Therapy Essentials

Humidification – Add when flow rate exceeds 4 L/min to prevent mucosal drying.
Cylinder colour – Oxygen = black with white shoulders; nitrogen = black; nitrous oxide = light blue; carbon dioxide = grey.
Nasal cannula setup – Connect tubing to oxygen source first, adjust flow rate, then insert prongs and secure behind ears.

Oxygenation Needs · Nursing Foundations

Suctioning & Pulse Oximetry

Suctioning safety

Suctioning clears secretions but can cause hypoxaemia, mucosal trauma, atelectasis and vagal bradycardia. Pre-oxygenate with 100% O2 for 30–60 seconds, limit each pass to 10 seconds, and suction only while withdrawing the catheter.

Suction Pressure Guidelines

Patient	Pressure (mm Hg)
Adults	100–120
Infants and children	80–100
Neonates	60–80

Pulse Oximetry (SpO2)

Normal – 95–99%; below 90% is hypoxaemia (emergency).
COPD target – 88–92% to avoid oxygen-induced respiratory depression in chronic CO2 retainers.
Interferences – Nail polish, bandaging, poor circulation, intravascular dyes, carboxyhaemoglobin (falsely high).
Improve signal – Warm extremity, reposition probe, remove nail polish, keep patient still; use earlobe, toe or forehead sensor.

A pulse oximeter clipped onto a patient's finger displaying oxygen saturation reading. — Pulse oximeter device