Non-Invasive Ventilation (NIV/BiPAP/CPAP)

Overview

COPD / BiPAP

CPO / CPAP

Monitoring

GCC Context

MCQ Practice

🫁 What is Non-Invasive Ventilation?

Non-Invasive Ventilation (NIV) delivers ventilatory support via a tight-fitting face or nasal mask — WITHOUT an endotracheal tube. It reduces the need for intubation, associated complications, and ICU stay.

BiPAP (Bi-level Positive Airway Pressure)

Delivers TWO pressure levels: IPAP (inspiratory) and EPAP (expiratory)
IPAP > EPAP → pressure support aids inspiration
Reduces work of breathing; improves alveolar ventilation; reduces CO₂
First-line for COPD exacerbation with hypercapnic failure
Also: obesity hypoventilation, neuromuscular disease

CPAP (Continuous Positive Airway Pressure)

Delivers ONE constant pressure throughout breathing cycle
Keeps alveoli open (recruits collapsed alveoli)
Reduces preload and afterload in cardiogenic pulmonary oedema
Does NOT assist inspiration directly
First-line for cardiogenic pulmonary oedema; sleep apnoea

Key Difference: BiPAP vs CPAP

Feature	BiPAP	CPAP
Pressure levels	2 (IPAP + EPAP)	1 (constant)
CO₂ removal	Yes (effective)	Minimal
Inspiratory support	Yes	No
Main indication	Hypercapnic failure (COPD)	Hypoxaemic failure (CPO, OSA)
EPAP = PEEP equivalent	EPAP 4–5 cmH₂O typically	CPAP 5–10 cmH₂O typically

Indications for NIV

COPD exacerbation with hypercapnic respiratory failure (pH 7.25–7.35, PaCO₂ >6 kPa)
Acute cardiogenic pulmonary oedema (CPAP or BiPAP)
Obesity hypoventilation syndrome
Neuromuscular disease (MND, myasthenia gravis, post-polio)
Chest wall deformity (severe kyphoscoliosis)
Post-extubation respiratory failure in COPD/immunocompromised patients
Immunocompromised with respiratory failure (reduces intubation and VAP risk)

Contraindications to NIV

Absolute Contraindications:

Respiratory arrest / apnoea
Inability to protect airway (GCS ≤8, absent cough/gag)
Vomiting / high aspiration risk
Undrained pneumothorax
Severe facial trauma / burns precluding mask fit
Recent upper GI surgery
Haemodynamic collapse requiring immediate intubation

🌬️ NIV for COPD Exacerbation (BiPAP)

Indications for BiPAP in COPD

pH <7.35 AND PaCO₂ >6 kPa (45 mmHg) on optimised medical therapy
Respiratory rate >23 breaths/min despite bronchodilators/steroids
Clinical signs of respiratory distress: accessory muscle use, paradoxical breathing

NIV should be started within 60 minutes of diagnosis of hypercapnic failure in COPD. Do not delay awaiting transfer to HDU — begin NIV on the ward if HDU unavailable.

Initial BiPAP Settings for COPD

Parameter	Starting Setting	Titration
IPAP (Inspiratory Positive Airway Pressure)	10–12 cmH₂O	Increase by 2–3 cmH₂O every 20–30 min to max 20–25 cmH₂O targeting RR <25 and pH improvement
EPAP (Expiratory PAP)	4–5 cmH₂O	Increase to 5–8 if significant dynamic hyperinflation (PEEP effect needed)
Back-up rate (spontaneous-timed mode)	12–15 breaths/min	Provides mandatory breath if patient apnoeic
FiO₂ / supplemental O₂	Titrate to SpO₂ 88–92%	COPD: avoid hyperoxia — worsens hypercapnia

COPD oxygen target: SpO₂88–92% (NOT 94–98%). High-flow O₂ in COPD can suppress hypoxic drive, worsen V/Q mismatch (Haldane effect), and increase PaCO₂. Target 88–92%.

ABG Targets on BiPAP

Check ABG at 1 hour and 4 hours after starting NIV
Goal: pH trending upward toward ≥7.35
PaCO₂ falling (or at minimum, not worsening)
PaO₂ ≥7.5–8 kPa (SpO₂ 88–92%)

Mask Types for NIV

Full Face Mask (FFM)

Covers nose and mouth
Standard for acute NIV — less leak, better tolerance in acute breathlessness
Claustrophobia risk; cannot eat/drink with mask on

Nasal Mask / Nasal Pillows

Covers nose only (nasal mask) or just nasal prongs
Better tolerated long-term, allows speech and coughing
Significant air leak if mouth breathing (mouth breathing defeats nasal-only mask)
Preferred for home NIV / chronic NIV users

Preventing Pressure Injuries from NIV Mask

Apply protective dressing (hydrocolloidal foam) to bridge of nose before mask application
Check mask fit and skin condition every 2–4 hours
Give planned mask breaks (20–30 min every 4–6 hours for meals and oral care) once stabilised
Rotate mask type if prolonged NIV to redistribute pressure

❤️ NIV for Cardiogenic Pulmonary Oedema (CPAP)

How CPAP Helps Cardiogenic Pulmonary Oedema (CPO)

Reduces preload: Positive intrathoracic pressure decreases venous return to heart
Reduces afterload: Increases intrathoracic pressure, reducing left ventricular transmural pressure
Recruits collapsed alveoli: Improves V/Q matching and oxygenation
Reduces work of breathing: Patient breathes against positive pressure stent → reduces respiratory muscle fatigue

CPAP Settings for Cardiogenic Pulmonary Oedema

Parameter	Setting
Starting CPAP pressure	5–7.5 cmH₂O
Titrate to	Increase by 2.5 cmH₂O every 15–30 min, up to max 10–15 cmH₂O
FiO₂ target	Start 100%; wean to maintain SpO₂ ≥94%

3CPO Trial evidence: CPAP and BiPAP both reduced need for intubation and improved oxygenation faster than standard O₂ in cardiogenic pulmonary oedema. Neither showed mortality benefit over the other — either modality is appropriate.

BiPAP vs CPAP for Cardiogenic Pulmonary Oedema

Both are acceptable. Some centres use:

CPAP 5–10 cmH₂O for mild-moderate CPO
BiPAP IPAP 10–14 / EPAP 4–6 for patients with tachypnoea and increased work of breathing who may also benefit from inspiratory support

Important: Concurrent medical treatment is essential. CPAP/BiPAP buys time — but the underlying heart failure must be treated simultaneously:

IV furosemide (diuresis)
GTN infusion (vasodilation, preload reduction)
Sit patient upright
Treat precipitant (AF, MI, hypertensive crisis)

CPAP for Obstructive Sleep Apnoea (OSA) in GCC

Obesity is highly prevalent in GCC (30–50% obesity rates in some Gulf states) — OSA is correspondingly common
Home CPAP is first-line treatment for moderate-severe OSA
Pressures typically 5–15 cmH₂O (auto-titrating CPAP or fixed pressure per sleep study)
Regular mask cleaning and filter changes essential

📊 Monitoring NIV and Failure Criteria

Monitoring Schedule

Parameter	Frequency	Target
SpO₂	Continuous	COPD: 88–92%; CPO: ≥94%
Respiratory rate	Every 30–60 min	RR falling toward <25
Heart rate, BP	Every 30–60 min	Stabilising / improving
ABG	1 hour then 4 hours	pH rising; PaCO₂ falling (COPD)
GCS / consciousness	Every 1–2 hours	Improving or stable
Mask comfort / skin	Every 2–4 hours	No pressure sores; adequate seal
Air leak (visible fogging)	Continuously	Minimise significant leak

⚠️ Signs of NIV Failure — Escalate to Intubation

Consider urgent intubation if:

pH <7.25 after 1 hour of optimal NIV
pH worsening (not improving) on serial ABGs
SpO₂ <88% on maximum FiO₂ despite NIV
GCS declining — losing ability to protect airway
Respiratory arrest or apnoea
Patient cannot tolerate mask / excessive distress
Worsening haemodynamic instability

Do NOT persist with NIV in a rapidly deteriorating patient — delayed intubation worsens outcomes.

NIV Success Criteria (Can Consider Weaning)

pH ≥7.35 sustained on NIV
PaCO₂ within acceptable range (COPD may have chronic CO₂ retention)
RR <20 breaths/min at rest
SpO₂ maintained on reduced FiO₂
Patient alert and cooperative

Weaning NIV

Planned mask breaks, increasing in duration as tolerated
Reduce IPAP gradually (2 cmH₂O steps) as respiratory status improves
Transition to controlled oxygen when tolerated off NIV for 2–4 hours
Continue nocturnal NIV in established chronic respiratory failure patients

🌍 GCC-Specific Context

COPD Prevalence and Risk Factors in GCC ▼

COPD increasingly recognised in GCC — historically under-diagnosed due to lower smoking awareness in women and cultural barriers to spirometry referral
Shisha (hookah/waterpipe) smoking is a major COPD risk factor in GCC — equivalent to 100+ cigarettes per session of particulate exposure
Dust, sand storms (haboob), and industrial air pollution in GCC contribute to obstructive lung disease
Biomass fuel exposure (cooking fires) among domestic workers from South Asia/Africa increases COPD risk
COPD exacerbations are common ED presentations in winter months across all GCC hospitals

NIV Use During COVID-19 in GCC ▼

During COVID-19 pandemic, GCC hospitals rapidly expanded NIV capacity
NIV (BiPAP/CPAP) widely used in COVID-19 pneumonia where HFNC failed or was unavailable
Full face masks with exhalation filters used to reduce aerosol risk during pandemic
Dedicated NIV side rooms with negative pressure established in GCC hospitals for COVID-19 patients
Helmet CPAP (used widely in Europe) less common in GCC but available at major tertiary centres

Obesity Hypoventilation in GCC (OSA/OHS) ▼

Obesity rates in GCC among highest globally (KSA 35.4%; Kuwait 37.9%; Qatar 35.1% — WHO data)
Obesity Hypoventilation Syndrome (OHS = BMI ≥30 + chronic daytime hypercapnia without other cause) is a growing indication for home NIV in GCC
CPAP programmes are well-established through sleep centres at major GCC hospitals (KFSH, Cleveland Clinic Abu Dhabi, HMC Qatar)
Weight loss and bariatric surgery increasingly available in GCC may reduce future NIV burden

SCFHS / DHA / QCHP Exam Focus ▼

BiPAP has two pressures: IPAP (inspiratory) and EPAP (expiratory) — reduces CO₂; first-line for COPD
CPAP has one pressure — recruits alveoli; first-line for cardiogenic pulmonary oedema and OSA
COPD SpO₂ target on NIV: 88–92% (NOT 94–98%)
Check ABG at 1 hour of NIV — if pH not improving, escalate to intubation
Contraindications to NIV: apnoea, vomiting, GCS ≤8, undrained pneumothorax
NIV failure: pH <7.25 after 1 hour, declining GCS, SpO₂ not responding
Pressure injury prevention: protective dressing on nose bridge before mask application
CPAP helps cardiogenic pulmonary oedema by reducing preload AND afterload

📝 MCQ Practice

1. A COPD patient is started on BiPAP. After 1 hour, ABG shows pH 7.24, PaCO₂ 9.8 kPa, PaO₂ 8.2 kPa. SpO₂ is 92%. What is the appropriate next step?

✅ C — pH <7.25 after 1 hour of optimal NIV is a failure criterion requiring escalation to intubation. Continuing NIV in a patient with worsening acidosis delays definitive airway management. Increasing FiO₂ would worsen hypercapnia in COPD.

2. A patient with acute cardiogenic pulmonary oedema is on CPAP 7.5 cmH₂O. How does CPAP improve this condition physiologically?

✅ C — CPAP in cardiogenic pulmonary oedema works by: (1) reducing venous return (preload reduction), (2) reducing LV transmural pressure (afterload reduction), and (3) recruiting flooded/collapsed alveoli to improve oxygenation. These haemodynamic benefits are key to CPO management.

3. A COPD patient is receiving BiPAP. His SpO₂ is 96% on FiO₂ 40%. His nurse is happy with this. What concern should be raised?

✅ B — In COPD, the target SpO₂ is 88–92%. Excessive O₂ causes: (1) Haldane effect — CO₂ displaces O₂ from haemoglobin → rising PaCO₂, (2) suppressed hypoxic drive, (3) worsened V/Q mismatch from pulmonary vasoconstriction reversal. Reduce FiO₂ to target 88–92%.

4. Which of the following is an ABSOLUTE contraindication to starting NIV?

✅ C — Vomiting + declining consciousness = high aspiration risk + inability to protect airway. These are absolute contraindications to NIV. Aspirating stomach contents into lungs during NIV is catastrophic. This patient requires intubation with rapid sequence induction (RSI). Claustrophobia and beard leakage are challenges but not absolute contraindications.