Oxygenation and Respiratory Nursing

In depth

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Why the signs come in that order

Open RN separates hypoxia, low oxygen in the tissues, from hypoxemia, a low PaO₂ on the blood gas. Hypoxia can come from the lungs, the heart or anemia. Restlessness, anxiety, confusion and a rising heart rate come first; as it worsens, consciousness and vital signs deteriorate and SpO₂ falls; cyanosis is late; clubbing is a sign of long-standing hypoxia. Pulse oximetry is an estimate: severe anemia and poor peripheral circulation both make it unreliable, and a PaO₂ from an ABG is not affected by hemoglobin (Open RN 11.2).

Carbon dioxide behaves differently. When it builds quickly, as in an acute asthma attack that is tiring out or after too much opioid, the client becomes drowsy and confused. Open RN notes that consciousness becomes depressed once the PaCO₂ passes about 75–80 mm Hg in someone with normal lungs, while a client with chronic hypercapnia may show no symptoms until it passes 90–100. BTS lists drowsiness, new breathlessness or falling saturation in a client at risk of hypercapnia as reasons to check a blood gas; a pulse oximeter cannot show the CO₂.

Open RN lists the bedside interventions for a hypoxic client in this order: raise the head of the bed, coach breathing and coughing, check that the oxygen equipment is on, connected to the green oxygen outlet, set correctly and not kinked, consider respiratory medications, suction the mouth if secretions pool, treat pain, watch for opioid sedation, plan rest periods, and look for other causes such as anemia or unrecognized sleep apnea.

Oxygen devices in more detail

How well a cannula or mask works depends on its fit and on how hard the client is breathing (Open RN). A Venturi mask uses colored or labeled adaptors that each give a set FiO₂ from 24% to 60%; the adaptor, not the flowmeter number, sets the percentage, so check with the respiratory therapist before changing the flow. BTS advises raising Venturi flow by up to 50% if the respiratory rate is above 30. A cannula is less effective in a mouth breather or with blocked nostrils.

A partial rebreather looks like a nonrebreather but has no one-way valves, so it delivers less (about 35–50% in Open RN). A nonrebreather has valves between bag and mask and over the exhalation ports; Open RN warns of a high risk of suffocation if the gas flow is interrupted, which is why the bag must never collapse. High-flow nasal cannula is set up by the respiratory therapist and then maintained by the nurse; clients who need it are usually critically ill and need close monitoring.

CPAP gives one continuous pressure and is the usual treatment for obstructive sleep apnea; BiPAP gives a higher pressure on inhalation and a lower one on exhalation and is used in the hospital for acute respiratory failure as an alternative to intubation. Home humidifiers on these machines take distilled or sterile water, never tap water (Open RN 11.3).

Fire safety: oxygen feeds combustion. No smoking, open flames, gas stoves or kerosene heaters nearby; keep delivery equipment at least 5 feet from heat; avoid spark sources such as electric razors and hair dryers with a cannula in use; never use petroleum products on the lips or nose. Store cylinders upright and secured, never on the bed, and check the tank level before transport (Open RN 11.3).

COPD and oxygen: the reasoning

BTS warns against excessive oxygen in COPD. If a client develops hypercapnia or respiratory acidosis from too much oxygen, step the oxygen down to the lowest level that keeps SpO₂ at 88–92%; stopping it outright risks life-threatening rebound hypoxemia. The fix is controlled oxygen, not none. BTS suggests a target of 88–92% for clients at risk of hypercapnic failure until a blood gas is available, starting with a 24% Venturi at 2–3 L/min, a 28% Venturi at 4 L/min, or a cannula at 1–2 L/min, and repeating the gas 30–60 minutes after a change. If the pH and PaCO₂ turn out to be normal and there is no history of needing NIV or intubation, the target can be reset to 94–98%. If the client is critically ill, BTS starts with the same high-concentration oxygen as anyone else, then adjusts once the gas is back.

GOLD 2026 says a hypoxemic client with a COPD exacerbation should get controlled oxygen and be assessed for whether noninvasive ventilation is needed. AARC 2022 sets the same targets as BTS: 94–98% for most hospitalized adults and 88–92% with COPD.

Keeping the target range written in the order matters: BTS asks that the target stay on the chart even after oxygen is stopped so that early warning scores are read against the right range.

Incentive spirometry and airway clearance: evidence

The AARC 2011 guideline does not recommend incentive spirometry on its own to prevent postoperative lung complications, and found deep breathing exercises about as effective. It recommends IS together with deep breathing, directed coughing, early mobilization and good pain control, and suggests a volume-oriented device. For the exam, the technique still matters: slow deep inhalation while sitting upright, a breath hold of about 5 seconds, and about 10 repetitions an hour while awake (Open RN).

Huff coughing helps clients who have trouble coughing. Vibratory PEP devices create back-pressure and vibration that hold airways open and loosen mucus; they require a prescription and respiratory therapy input. Chest physiotherapy and inflatable vest devices are other options a respiratory therapist may add (Open RN 11.2).

Suctioning and trach care: the details

The AARC 2022 suctioning guideline limits each suctioning procedure to 15 seconds, recommends preoxygenation for adults and children, and a catheter that fills less than half of the airway's lumen (less than 70% in neonates). Adult vacuum is kept below −200 mm Hg (−120 for children and neonates), and as low as will clear the secretions. That is an outer limit, not a target: Open RN, the usual source of exam answers, teaches 100–150 mm Hg for adults on wall suction and says not to exceed 150 because higher pressure causes mucosal trauma, hypoxemia and atelectasis. Saline instillation is generally avoided; most studies found it can worsen oxygenation. Open RN gives the reason for the time limit: to prevent hypoxia. Deep suctioning (to resistance at the carina, then pulling back 1 cm) is reserved for when shallow suctioning, to the end of the tube, has not worked.

Open RN lists the complications to watch for during and after suctioning: hypoxemia, bradycardia and other dysrhythmias, blood pressure changes, bronchospasm, laryngospasm, mucosal bleeding, raised intracranial pressure and infection. Document secretion color, amount and consistency, and SpO₂ and lung sounds before and after.

During trach care the inner cannula is removed with the nondominant hand, brushed in saline, rinsed, dried and locked back in; a client who needs continuous oxygen keeps it near the outer cannula meanwhile. Clean the stoma with saline, one swab per stroke, moving out from the top; Open RN advises against hydrogen peroxide. If the client is ventilated, keep the head of the bed at 30–45° to reduce ventilator-associated pneumonia.

NTSP red flags that a tube may be blocked or displaced: the client can suddenly talk or air bubbles at the mouth with the cuff inflated, the cuff needs more and more air, noisy breathing or stridor, the tube looks displaced, new bleeding, rising respiratory rate, falling SpO₂, and new anxiety or agitation. A laryngectomy client has only one airway, at the front of the neck; the mouth does not connect to the lungs, so oxygen and rescue breaths go to the stoma.

Chest tubes: troubleshooting in depth

The water seal is a one-way valve: air leaves the pleural space on exhalation and cannot return. Tidaling (water rising and falling with breaths) means the tube is patent. It stops when the lung has re-expanded, or when the tubing is kinked, clotted or blocked, so assess the client before deciding which. Any water-seal bubbling means air is leaving the pleural space (an air leak). With a pneumothorax, intermittent bubbling on exhalation or cough is expected early and is the test used to confirm a leak is still present (Roebker 2023); it should decrease and stop. Continuous bubbling, a new or larger leak, or bubbling after the lung has re-expanded: exclude a tubing leak, then notify.

To find a continuous leak, Open RN describes clamping briefly with rubber-tipped clamps, starting at the dressing. If the bubbling stops when the clamp is next to the chest, the leak is at the insertion site or inside the chest: unclamp, reinforce the dressing and call the provider. If it continues, move the clamp down the tubing about every 10–12 inches; where it stops, the leak is in that segment. If it never stops, the drainage unit itself leaks and needs replacing. Always release the clamp.

Open RN gives these calls to the provider: bright red drainage over 200 mL an hour, especially if it averages that for 4 hours (a bleeding vessel that may need surgery), cloudy drainage (infection), drainage that suddenly stops in the first 24 hours (clot, kink or a tube that has moved), new or spreading subcutaneous emphysema (mark its edges), decreased breath sounds, and SpO₂ below 90% or a sudden increase in dyspnea, which needs emergency help. Change the unit before the collection chamber is full.

Teach the client to sit upright, splint with a pillow to cough, do deep breathing or IS, change position and walk as ordered, and report any trouble breathing at once.

Worked ABG examples

Open RN notes that the lungs compensate quickly for metabolic problems, while the kidneys take longer to compensate for respiratory ones, which is why chronic COPD can show a normal pH with a high PaCO₂ and a high HCO₃⁻. Open RN lists critical values that need urgent action: pH below 7.25 or above 7.60, PaCO₂ below 25 or above 60, HCO₃⁻ below 10 or above 40, PaO₂ below 60 and SaO₂ below 88%.

Exam pearls

• First action for a hypoxic client is usually to raise the head of the bed and check the airway and oxygen equipment; then apply or increase oxygen per protocol.
• Restlessness is an early sign; cyanosis is late. Do not wait for cyanosis.
• COPD target 88–92%: titrate, do not stop oxygen.
• Venturi = precise FiO₂; nonrebreather = highest FiO₂ without an airway; simple mask never below 5 L/min.
• Suction: adult wall setting 100–150 mm Hg, preoxygenate, no suction going in, 15 seconds or less, two passes at most, stop for bradycardia.
• Trach: obturator and spare tubes at the bedside; ties changed with a helper; one finger under the tie. Dislodged and in distress: call for help, oxygen to face and stoma; reinsert only if trained and policy allows.
• Chest tube: unit below the chest, never strip, never routinely clamp, continuous bubbling = leak, three-sided dressing if pulled out, sterile water if disconnected.
• ABG: ROME, then check compensation. Vomiting = alkalosis; diarrhea = acidosis.