Incentive Spirometry 

It is designed to:

• Increase transpulmonary pressure
• Promote alveolar recruitment
• Reverse or prevent atelectasis
• Improve inspiratory muscle performance
• Encourage periodic deep breathing after surgery or prolonged immobilization

The basic principle is:

Transpulmonary Pressure=Alveolar Pressure−Pleural Pressure

Deep inspiration increases transpulmonary pressure, leading to alveolar expansion.

Why Are Postoperative Pulmonary Complications Common?

After surgery, especially:

• Upper abdominal surgery
• Thoracic surgery
• Cardiac surgery

Patients develop:

1. Pain

Pain inhibits deep breathing.

2. Reduced Functional Residual Capacity (FRC)

FRC falls significantly after surgery.

3. Diaphragmatic Dysfunction

Particularly after abdominal surgery.

4. General Anesthesia Effects

Causes:

• Atelectasis
• Reduced lung volumes
• Reduced mucociliary clearance

5. Immobilization

Promotes secretion retention and collapse of dependent alveoli.

Physiological Effects

Pulmonary Effects

• Increase Inspiratory Capacity
• Increase Vital Capacity
• Increase FRC
• Improve Alveolar Recruitment
• Improve Ventilation Distribution
• Improve Cough Effectiveness
• Improve Secretion Clearance

Respiratory Muscle Effects

Acts as a mild inspiratory muscle trainer.

Improves:

• Diaphragm excursion
• Inspiratory endurance
• Respiratory muscle activation

Types of Incentive Spirometers

1. Volume-Oriented Incentive Spirometer

Most commonly used.

Measures:Volume inspired

Patient attempts to raise a piston to a target volume.

Advantages

• Better diaphragmatic activation
• Lower work of breathing
• More physiological inspiration

Preferred in many ICUs.

2. Flow-Oriented Incentive Spirometer

Uses balls that rise according to inspiratory flow.

Patient raises 1–3 balls.

Measures:Inspiratory flow rather than volume.

Disadvantages

• More accessory muscle use
• Less diaphragmatic breathing
• Higher work of breathing

Typical calibration (varies by manufacturer):

Volume vs Flow Spirometry

Indications

Postoperative Patients

Most common indication.

Thoracic surgery

• Lobectomy
• Pneumonectomy
• VATS

Upper abdominal surgery

• Gastrectomy
• Hepatectomy
• Whipple surgery

Cardiac surgery

• CABG
• Valve surgery

Major vascular surgery

ICU Patients

• Prolonged bed rest
• Mechanical ventilation weaning
• Post-extubation rehabilitation
• Atelectasis
• Rib Fractures
• Chest Trauma
• Neuromuscular Weakness
• COPD
• Restrictive Lung Disease

Contraindications

Absolute Contraindications

Inability to cooperate

• Severe encephalopathy
• Severe delirium
• Deep sedation

Inability to generate inspiratory effort

Examples:Severe neuromuscular paralysis

Relative Contraindications

• Severe respiratory distress
• Hemodynamic instability
• Untreated pneumothorax
• Severe pain
• Facial trauma
• Recent oral surgery
• Elevated ICP with poor tolerance

Technique of Incentive Spirometry

Step 1-Sit upright.

Step 2-Hold device vertically.

Step 3-Exhale normally.

Step 4-Seal lips around mouthpiece.

Step 5-Inhale slowly and deeply.

Step 6-Raise piston to target.

Step 7-Hold inspiration 3–5 seconds (up to 10 seconds if possible).

Step 8-Remove mouthpiece.

Step 9-Exhale normally.

Step 10-Repeat.

Ideal Maneuver

The desired pattern is:

• Slow inspiration
• Deep inspiration
• Sustained inspiratory hold

Avoid:

• Rapid sucking
• Short breaths
• Hyperventilation

Recommended Frequency

10 breaths every hour while awake

Many institutions use:10 slow inspirations-Every 1–2 hours

Followed by:Coughing and Mobilization

Setting Target Volume

Usually based on:

• Age—Height—Sex
• baseline inspiratory capacity

Target is gradually increased.

Example:Initial target:1000 mL

Progressively increased to:1500–2500 mL depending on patient characteristics.

For average adults:

Remember that a daily upward trend is more important than any single value.

Incentive Spirometry vs PEP Therapy

Evidence and Controversy

Traditional Belief

IS prevents:

• Atelectasis
• Pneumonia
• Respiratory failure

Modern Evidence

Several systematic reviews and meta-analyses have failed to show a clear reduction in postoperative pulmonary complications when incentive spirometry is used alone after abdominal or cardiac surgery. 

Current evidence suggests that IS is best viewed as one component of a multimodal pulmonary care strategy, rather than a standalone intervention. It is commonly combined with deep breathing exercises, coughing, adequate analgesia, and early mobilization. 

AARC Recommendations

The American Association for Respiratory Care (AARC) recommends that incentive spirometry should not be used as the sole therapy for prevention of postoperative pulmonary complications.

Instead it should be combined with:

• Directed coughing
• Deep breathing exercises
• Early mobilization
• Adequate pain control