What is the appropriate emergency assessment and management for a patient presenting with acute respiratory failure?

Emergency Assessment and Management of Acute Respiratory Failure

Immediately determine cardiopulmonary stability and triage patients with respiratory failure to a resuscitation area where advanced respiratory and cardiovascular support is available. 1, 2

Initial Assessment (First 5 Minutes)

Use the ABCDE approach systematically to identify life-threatening problems 3:

Airway and Breathing Assessment

• Check for airway patency and signs of respiratory distress: SpO₂ <90%, respiratory rate >25, use of accessory muscles, orthopnea, or inability to speak in full sentences 1, 4
• Monitor oxygen saturation continuously with pulse oximetry from the moment of patient contact 2
• Position patient upright to reduce work of breathing 1

Circulation and Mental Status

• Assess hemodynamic stability: systolic blood pressure <90 mmHg indicates cardiogenic shock or severe hypoperfusion requiring immediate ICU transfer 5, 4
• Use AVPU mnemonic (Alert, Visual, Pain, Unresponsive) to rapidly assess mental status as an indicator of hypoperfusion and tissue oxygenation 1, 2
• Check peripheral perfusion: capillary refill, skin temperature, and mottling 2

Immediate Interventions

Oxygen Therapy and Ventilatory Support

Administer supplemental oxygen immediately if SpO₂ <90%, but avoid hyperoxia 1, 2

For patients with respiratory distress (SpO₂ <90%, RR >25, increased work of breathing, orthopnea):

• Start non-invasive ventilation (NIV) as soon as possible - CPAP is preferred initially as it is simpler and feasible even in pre-hospital settings 1
• NIV reduces respiratory distress and may decrease intubation and mortality rates 1, 6
• Target SpO₂ between 85-90% with supplementary oxygen 1

If persistent respiratory distress after 60-90 minutes of CPAP:

• Check arterial or venous blood gas for pH and pCO₂ 1
• If significant hypercapnia and acidosis present: switch to pressure-support with PEEP (PS-PEEP), particularly in patients with COPD history or signs of fatigue 1
• If normal pH and pCO₂: continue CPAP 1
• If no improvement in PaCO₂ and pH after 4-6 hours despite optimal settings, discontinue NIV and proceed to intubation 1

Contraindications to NIV

Do not use NIV if 1:

• Recent upper gastrointestinal or facial surgery
• Inability to protect airway
• Copious respiratory secretions
• Life-threatening hypoxemia unresponsive to initial oxygen
• Severe agitation or confusion preventing mask tolerance
• Vomiting or bowel obstruction

Note: NIV can still be used in these situations if a decision has been made not to intubate, but have contingency plans ready 1

Diagnostic Workup (Within First Hour)

Immediate Tests

• 12-lead ECG to exclude ST-elevation MI and identify arrhythmias 5, 2
• Chest X-ray to identify pneumonia, pulmonary edema, pneumothorax, or pleural effusions (recognizing it may be normal in up to 20% of cases) 1, 2
• Arterial blood gas only when precise measurement of oxygen and carbon dioxide partial pressures is needed; venous sample acceptably indicates pH and CO₂ 1

Laboratory Assessment

Obtain the following blood tests immediately 1:

• Cardiac troponin
• BUN/creatinine
• Electrolytes (sodium, potassium)
• Glucose
• Complete blood count
• BNP or NT-proBNP if acute heart failure suspected 1, 5
• D-dimer if pulmonary embolism suspected 1

Advanced Imaging

• Bedside thoracic ultrasound (if expertise available) can rapidly identify interstitial edema (B-lines), pleural effusions, and pericardial effusion 1
• Immediate echocardiography is mandatory only for cardiogenic shock; otherwise perform after stabilization 1

Ongoing Monitoring

Monitor continuously for at least 24 hours 1, 5:

• Oxygen saturation
• Blood pressure
• Heart rate and rhythm (continuous ECG)
• Respiratory rate
• Mental status
• Urine output
• Peripheral perfusion

Reassess arterial blood gas after 1-2 hours of NIV, then again at 4-6 hours if earlier sample showed little improvement 1

Review patients on NIV regularly to assess response to treatment and optimize ventilator settings 1

Common Pitfalls

• Delaying NIV in patients with respiratory distress - start as soon as possible, not after conventional oxygen fails 1
• Routine arterial blood gas in all patients - only needed when precise measurement required 1
• Continuing NIV beyond 4-6 hours without improvement - this delays necessary intubation and worsens outcomes 1
• Using morphine routinely - associated with higher rates of mechanical ventilation and death; avoid unless specific indication 1
• Treating pneumothorax with NIV before chest tube placement - insert intercostal drain first in most cases 1

Location of Care

Patients with more severe acidosis (pH <7.30) or those not improving after 1-2 hours should be managed in HDU or ICU 1

Patients with respiratory failure from causes where NIV role is unclear (pneumonia, ARDS, asthma) should only receive NIV in HDU/ICU where immediate intubation is available 1