BNS Section 7: Oxygenation, Ventilation, and Gas Exchange

Section Overview

Adequate oxygenation, ventilation, and gas exchange are prerequisite physiological conditions for virtually every other organ system’s function. Hypoxia — insufficient oxygen delivery to tissues — can cause irreversible organ damage within minutes. Nurses are responsible for continuously assessing respiratory status, identifying early signs of compromise, selecting and managing supplemental oxygen delivery, and implementing interventions that optimize ventilation and gas exchange across all patient populations.

This section covers the respiratory assessment framework, oxygen delivery systems and their clinical applications, positioning for respiratory optimization, incentive spirometry, and suctioning technique. These skills integrate directly with assessment (Section 1), infection control (Section 3), and the nursing process (Section 2).

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Learning Objectives

By the end of this section, students will be able to:

1. Perform a systematic respiratory assessment including rate, depth, pattern, breath sounds, and SpO₂. (Bloom’s: Apply)
2. Select and apply the appropriate oxygen delivery system based on the patient’s clinical presentation and prescribed flow rate. (Bloom’s: Analyze)
3. Identify the signs and symptoms of hypoxia, hypoxemia, hypercapnia, and respiratory failure requiring immediate intervention. (Bloom’s: Analyze)
4. Instruct and assist patients in using the incentive spirometer correctly to promote lung expansion. (Bloom’s: Apply)
5. Perform oropharyngeal suctioning using clean technique and tracheal suctioning using sterile technique. (Bloom’s: Apply)
6. Position patients therapeutically to optimize ventilation and gas exchange based on clinical condition. (Bloom’s: Apply)

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Respiratory Assessment

Components of a Complete Respiratory Assessment

A thorough respiratory assessment encompasses inspection, auscultation, and pulse oximetry, integrated with the patient’s history and clinical context.

Inspection:

• Respiratory rate — count for a full 60 seconds without patient awareness; normal adult range 12–20 breaths/min
• Depth — tidal volume appears shallow, normal, or deep
• Pattern — rhythm (regular, irregular), pattern type (see below)
• Work of breathing — use of accessory muscles (sternocleidomastoid, scalene, intercostals, abdominals); nasal flaring; pursed-lip breathing; tracheal tugging
• Chest wall — symmetry of expansion; paradoxical movement (flail chest); barrel chest
• Color — pallor, cyanosis (circumoral, peripheral, central); diaphoresis

Auscultation:

Auscultate all lung fields systematically, anterior and posterior, comparing side to side (never auscultate through clothing).

Breath Sound	Description	Associated Condition
Vesicular	Soft, breezy; heard over lung periphery	Normal peripheral lung tissue
Bronchial	Loud, hollow, tubular; heard over trachea	Normal over trachea; abnormal if heard over lung fields
Bronchovesicular	Combination; heard over mainstem bronchi	Normal over central airways
Crackles (rales)	Discontinuous, popping sounds; fine or coarse	Pulmonary edema, pneumonia, atelectasis
Wheezes	High-pitched, musical; continuous	Bronchospasm, asthma, COPD exacerbation
Rhonchi	Low-pitched, gurgling; continuous	Secretions in large airways
Stridor	High-pitched, harsh; heard without stethoscope	Upper airway obstruction — urgent finding
Pleural friction rub	Creaking, leathery; synchronous with breathing	Pleuritis, pulmonary embolism
Diminished / absent	Reduced or no air movement	Consolidation, effusion, pneumothorax, mucus plugging

Respiratory Patterns

Pattern	Description	Associated Condition
Eupnea	Normal rate and depth	Healthy state
Tachypnea	Rate > 20 breaths/min	Fever, anxiety, hypoxia, PE
Bradypnea	Rate < 12 breaths/min	Opioid overdose, increased ICP, CNS depression
Hyperpnea	Increased depth; rate may be normal	Exercise, metabolic acidosis
Kussmaul	Deep, rapid, labored; “air hunger”	Diabetic ketoacidosis
Cheyne-Stokes	Crescendo-decrescendo cycles with apneic pauses	End-of-life, heart failure, increased ICP
Biot’s (ataxic)	Irregular rate and depth with sudden apnea	Brainstem injury
Apnea	Absence of breathing	Emergency — requires immediate intervention

Recognizing Respiratory Compromise

The following findings in any combination constitute early warning signs of respiratory deterioration and require immediate nursing action (assessment, positioning, oxygen application, provider notification):

• SpO₂ < 90% or declining trend
• RR > 30 or < 8 breaths/min
• Increased work of breathing: accessory muscle use, nasal flaring, tripod positioning
• New or worsening crackles, wheezes, or stridor
• Cyanosis (central cyanosis is a late, ominous sign)
• Altered mental status — agitation or somnolence in a patient with respiratory distress

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Oxygen Delivery Systems

Supplemental oxygen is a medication. It requires a provider order specifying the flow rate (L/min) or target oxygen saturation range. The nurse selects the delivery device appropriate to the prescribed flow rate and patient condition.

Low-Flow Devices (Variable FiO₂)

Device	Flow Rate	Approximate FiO₂	Key Points
Nasal cannula (NC)	1–6 L/min	24–44%	Comfortable; allows eating and speaking; FiO₂ increases ~4% per L/min above 21%
Simple face mask	6–10 L/min	35–55%	Minimum 6 L/min to flush CO₂ from mask; not appropriate below 6 L/min
Partial rebreather mask	6–10 L/min	40–70%	Reservoir bag must remain at least 2/3 full on inhalation
Non-rebreather mask (NRB)	10–15 L/min	60–90%	Highest FiO₂ achievable without intubation; bag must not completely deflate; used for acute hypoxia

High-Flow Devices (Controlled FiO₂)

Device	FiO₂	Key Points
Venturi mask	24–50% (precisely controlled)	Best choice when precise FiO₂ is required (COPD, titration protocols); color-coded adapters set FiO₂
High-flow nasal cannula (HFNC)	Up to 100% at ≤ 60 L/min	Delivers heated, humidified oxygen; reduces work of breathing; reduces need for intubation in select patients

COPD and Supplemental Oxygen

Patients with chronic hypercapnia (elevated CO₂) secondary to severe COPD require careful oxygen titration. While the “hypoxic drive” theory has been overstated historically, it remains important to target SpO₂ 88–92% in this population (rather than ≥ 95%) to avoid suppressing the respiratory drive and worsening hypercapnia. Use a Venturi mask to deliver precisely controlled FiO₂ in these patients.

NCLEX-Style Practice Questions:

1. A nurse is caring for a patient with acute exacerbation of asthma. The patient has an SpO₂ of 88%, is using accessory muscles, and is in obvious respiratory distress. Which oxygen delivery device should the nurse apply first?

   • A) Nasal cannula at 2 L/min
   • B) Simple face mask at 5 L/min
   • C) Non-rebreather mask at 12–15 L/min ✓
   • D) Venturi mask at 24%

2. A nurse is providing care for a patient with COPD and chronic CO₂ retention. The provider orders oxygen therapy to maintain SpO₂ 88–92%. Which device best achieves this goal?

   • A) Non-rebreather mask at 15 L/min
   • B) Nasal cannula at 6 L/min
   • C) Venturi mask set to 28% ✓
   • D) Simple face mask at 8 L/min

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Positioning for Respiratory Optimization

Positioning is a simple, immediately available nursing intervention that can significantly improve oxygenation and reduce work of breathing.

Position	Effect on Respiration	Indications
High Fowler’s (90°)	Maximizes diaphragmatic excursion and lung expansion	Acute dyspnea, pulmonary edema, respiratory distress
Semi-Fowler’s (30–45°)	Good lung expansion; reduces aspiration risk	Routine post-operative positioning; patients on O₂
Lateral decubitus (good lung down)	Increases perfusion and ventilation to the dependent lung	Used in unilateral pneumonia to optimize V/Q matching
Prone positioning	Recruits posterior lung segments; reduces atelectasis	ARDS (used in ICU with mechanical ventilation; also investigated in COVID-19)
Tripod position	Patient leans forward, hands on knees; opens chest; reduces work of breathing	Acute asthma or COPD exacerbation (self-selected by patients in distress)

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Incentive Spirometry

Incentive spirometry (IS) is a breathing exercise device used to prevent atelectasis, particularly in post-operative, immobile, or shallow-breathing patients. By providing visual feedback, the device encourages sustained maximal inhalation that mimics a natural sigh breath.

Indications

• Post-operative patients (especially thoracic and abdominal surgery)
• Patients with shallow breathing due to pain, splinting, or immobility
• Prevention of hospital-acquired pneumonia in high-risk patients

Patient Instruction (Teach-Back)

1. Sit upright (Fowler’s or semi-Fowler’s) or stand if possible
2. Exhale normally and place lips completely around the mouthpiece
3. Inhale slowly and deeply while watching the indicator rise toward the target volume marker
4. Hold the breath for 3–5 seconds at the top of inhalation
5. Remove the mouthpiece and exhale normally
6. Rest briefly, then repeat 10 times per hour while awake
7. Follow each session with a deep cough to mobilize secretions

Instruct patients to hold a pillow against the abdomen or chest (splinting) to support the incision site during deep breaths and coughs, which reduces pain and increases willingness to perform the exercises.

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Suctioning

Suctioning removes secretions from the airway when the patient is unable to clear them effectively through coughing. It is indicated only when assessment reveals signs of secretion retention; routine suctioning on a time schedule is not evidence-based and can cause mucosal trauma, hypoxia, and infection.

Oropharyngeal Suctioning (Yankauer)

Used to clear the mouth and upper airway of secretions in alert or semi-alert patients who cannot swallow effectively.

• Use clean gloves and a Yankauer (rigid tonsil-tip) suction catheter
• Apply suction (80–120 mmHg for adults) and guide the tip along the cheek, avoiding the gag reflex trigger
• Do not apply suction while inserting the catheter
• Limit each pass to 10–15 seconds
• Reassess and repeat as needed; document amount, color, and consistency of secretions

Nasotracheal / Endotracheal Suctioning

Used to clear secretions from the trachea and lower airway in patients with artificial airways or those unable to clear secretions with coughing alone.

Requires sterile technique. Key safety considerations:

• Pre-oxygenate with 100% O₂ for 30–60 seconds before suctioning to minimize hypoxia
• Insert the catheter without suction during advancement; apply suction only during withdrawal
• Rotate the catheter gently during withdrawal; limit suction time to 10–15 seconds per pass
• Allow the patient to rest and re-oxygenate between passes (30–60 seconds)
• Suction pressure: 80–120 mmHg for adults; 60–100 mmHg for children
• Limit to the minimum number of passes needed to clear secretions
• Monitor heart rate and SpO₂ continuously during the procedure; stop if bradycardia, significant desaturation, or patient distress occurs

NCLEX-Style Practice Questions:

1. A nurse is about to perform nasotracheal suctioning on a patient. Which action should the nurse perform first?

   • A) Insert the suction catheter while applying suction
   • B) Pre-oxygenate the patient with 100% oxygen for 30–60 seconds ✓
   • C) Set the suction pressure to 150 mmHg for maximum secretion removal
   • D) Apply suction during the catheter insertion to prevent secretion accumulation

2. A post-operative patient has an SpO₂ of 93%, is taking shallow breaths due to incisional pain, and has diminished breath sounds bilaterally at the bases. Which nursing intervention is the priority?

   • A) Administer prescribed analgesic and encourage the use of incentive spirometry ✓
   • B) Apply a non-rebreather mask immediately
   • C) Perform nasotracheal suctioning
   • D) Place the patient flat to increase tidal volume

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Standards Alignment

This section supports the following professional and regulatory frameworks:

• AACN Essentials D1, D2, D3, D9: Knowledge for nursing practice; person-centered care; population health
• NCLEX-NG CJMM: Recognize Cues (RC), Analyze Cues (AC), Prioritize Hypotheses (PH), Generate Solutions (GS), Take Action (TA), Evaluate Outcomes (EO)
• QSEN: Patient-Centered Care (PCC), Evidence-Based Practice (EBP), Safety (S), Quality Improvement (QI)
• CCNE Standards I, II: Professional identity; curriculum outcomes
• ACEN Standards 3, 4: Student outcomes; oxygenation and respiratory care curriculum content