What are the causes and treatments for nocturnal dyspnea (shortness of breath at night)?

Nocturnal Dyspnea: Causes and Treatment Approach

Shortness of breath at night requires systematic evaluation for cardiac, pulmonary, and sleep-related causes, with treatment directed at the underlying condition rather than the symptom alone.

Primary Causes to Evaluate

Cardiac Causes

• Heart failure is a leading cause of nocturnal dyspnea, manifesting as paroxysmal nocturnal dyspnea (PND) due to fluid redistribution when recumbent, increasing pulmonary congestion 1, 2
• Sleep apnea independently worsens overnight hemodynamics in heart failure patients, with respiratory disturbance index correlating with overnight increases in atrial natriuretic peptide levels 2
• Assessment should include brain natriuretic peptide testing, ECG, and evaluation for ankle swelling 3, 1

Pulmonary Causes

• COPD and asthma commonly present with nocturnal symptoms, though many patients on inhalers lack confirmatory pulmonary function testing 4
• Restrictive lung diseases (neuromuscular disorders, chest wall deformities) present with progressive nocturnal hypoventilation, often with minimal daytime symptoms initially 1
• Any elevation of pCO2 in neuromuscular disease may herald impending crisis, even before respiratory acidosis develops 1

Sleep-Related Causes

• Obstructive sleep apnea directly causes nocturnal dyspnea and should be screened using tools like STOP-BANG questionnaire 3
• Sleep disorders affect 65-83% of patients with certain vascular malformations causing positional dyspnea 5

Other Medical Conditions

• Anemia, thyroid disorders, renal dysfunction, and endocrine disorders require evaluation through blood tests including electrolytes, renal function, thyroid function, calcium, and HbA1c 3, 6
• Medication review is essential, particularly diuretics, calcium channel blockers, lithium, and NSAIDs that may contribute to nocturia and nocturnal symptoms 3

Diagnostic Workup

Essential Initial Tests

• 72-hour bladder diary to establish overnight urine volume patterns if nocturia accompanies dyspnea 3
• Pulmonary function tests are mandatory before diagnosing obstructive airway disease, as 40.9% of patients on inhalers never had spirometry performed 4
• Blood gas assessment with oximetry and full blood gas analysis, particularly in suspected restrictive disease or hypercapnia 1
• Chest imaging (X-ray or CT) based on clinical suspicion and performance status 1

Physical Examination Focus

• Check for peripheral edema, orthostatic blood pressure changes, signs of respiratory muscle weakness, and abnormalities of gait or speech 3, 1
• Assess for signs of bulbar dysfunction in neuromuscular conditions, which affects cough effectiveness and upper airway patency 1

Treatment Algorithm

Step 1: Address Reversible Causes

Treat the underlying medical condition first, as this takes priority over symptomatic management on safety grounds 1

• Optimize heart failure therapy before considering nocturnal oxygen, as recumbency-induced pressure changes in blood vessels may increase diuresis; preventing this to reduce symptoms may worsen the underlying condition 1
• For COPD with acute hypercapnic respiratory failure, controlled oxygen therapy with target PaO2 is essential 1
• Treat sleep apnea with CPAP, which can substantially reduce nocturnal dyspnea, though compliance is often poor 1

Step 2: Non-Pharmacological Interventions

Implement these measures before pharmacological treatment and continue alongside it 1

• Elevate upper body positioning (coachman's seat position) 1
• Cool air directed at face, opening windows, using small ventilators 1
• Respiratory training and relaxation techniques to prevent panic during breathlessness episodes 1
• Education of patient and caregivers about these measures reduces helplessness and anxiety 1

Step 3: Ventilatory Support When Indicated

• NIV (non-invasive ventilation) is the treatment of choice for neuromuscular disease, chest wall deformity, and cystic fibrosis when ventilatory support is needed 1
• In restrictive lung disease, any breathless/acutely unwell patient should be considered for NIV before respiratory acidosis develops 1
• Nocturnal oxygen therapy alone should NOT be given for nocturnal hypoxaemia in COPD, neuromuscular weakness, or interstitial lung disease unless LTOT criteria are met 1
• If nocturnal oxygen is used (e.g., severe heart failure with sleep-disordered breathing), start at low flow rate of 1-2 L/min and monitor for worsening hypercapnia 1

Step 4: Pharmacological Symptom Management (Advanced Disease)

For palliation in advanced cancer or end-stage disease:

• Opioids are the only pharmacological agents with sufficient evidence for dyspnea palliation 1
• Start with lower doses than used for pain in opioid-naïve patients; increase by 25-50% in opioid-tolerant patients 1
• Oral/rectal normal-release preparations for titration, then switch to sustained-release 1
• Avoid morphine in severe renal insufficiency; adjust dosing for renal function 1
• Benzodiazepines can be used for anxiety-related breathlessness when opioids are insufficient 1

Critical Pitfalls to Avoid

• Do not prescribe inhalers without confirmatory pulmonary function testing—28.4% of patients on inhalers have no evidence of obstructive airway disease 4
• Do not give nocturnal oxygen alone for nocturnal desaturation in COPD, neuromuscular disease, or ILD without meeting LTOT criteria 1
• Do not overlook sleep disorders as contributors—screen systematically rather than assuming primary pulmonary or cardiac cause 3
• Do not fail to review all medications, including over-the-counter drugs that may contribute to symptoms 3
• In neuromuscular disease, do not wait for respiratory acidosis to develop before initiating NIV 1
• Do not use nebulized or inhaled opioids—there is no evidence for efficacy 1

Follow-Up Considerations

• Patients on long-term oxygen therapy require reassessment at 3 months with blood gases and flow rate verification, then at 6-12 month intervals 1
• Home visits within 4 weeks by specialist nurses to check compliance, smoking status, and symptoms of hypercapnia 1
• For heart failure with nocturnal oxygen, monitor for reduction in daytime sleepiness and repeat blood gas to exclude worsening hypercapnia 1