Noninvasive Ventilation: Pre- and Post-Procedural Know-How

Noninvasive Ventilation Noninvasive ventilation (NIV) is a widespread and effective practice that treats acute and chronic respiratory failure. Since it achieves its goals without direct tracheal intubation and its devastating consequences, the use of NIV has increased from rare to highly prevalent in many ICUs globally. 

In this article, Hospital Procedures Consultants describes its use in chronic obstructive pulmonary disease (COPD) and congestive heart failure (CHF).

What Constitutes Respiratory Failure?

Respiratory failure is a condition where the lungs retain too much carbon dioxide or cannot get enough oxygen from the blood. It is sudden and serious, requiring clinicians to be watchful of the following signs:

  • Tachypnea: Respiratory rate of less than 30 to 35 breaths per minute
  • Hypercapnia: PaCO2 is greater than 50 mmHg with pH less than 7.35
  • Hypoxemia: PaO2 becomes less than 60 mmHg

Respiratory failure is responsible for a third of in-hospital mortalities.

Noninvasive positive pressure ventilation improves the patient’s functional residual capacity (FRC), re-expands flooded alveoli, decreases left ventricular afterload, enhances cardiac output, and boosts lung compliance. However, its use should be limited to patients who can tolerate the mask and constant airflow.

NIV Contraindications 

There are two types of contraindications for NIV: absolute and relative.

Absolute contraindications include:

  • Acute severe asthma
  • Cardiac or respiratory arrest, which requires immediate intubation
  • Facial burns and deformities
  • Fixed upper airway obstruction
  • Severe nausea and vomiting 
  • Significant gastrointestinal bleeding
  • Untreated/undrained pneumothorax

If any of these occur, admit the patient into the intensive care unit (ICU) where endotracheal intubation (ETI) is readily available.

Relative contraindications include:

  • Bowel obstruction 
  • Confused, uncooperative, or agitated patients
  • Copious respiratory secretions
  • Depressed level of consciousness
  • Hemodynamic instability
  • Inability to protect the airway
  • Recent gastroesophageal, facial, or upper airway surgery
  • Severe comorbidity

NIV is also ill-advised for patients experiencing hypoxaemic respiratory failure. However, it may be considered for AIDS patients with severe PCP-related ARF, immunosuppressed patients with pneumonitis and ARF, and recipients of solid organ transplantation.

Ideal Candidates for NIV

Evaluating candidates for NIV requires examining the patient’s medical history and fitness level. The latter can be assessed with a chest x-ray (CXR) and arterial blood gases (ABGs).

If the patient has COPD, look for:

  • Arterial pH <7.35 (H+ >45 nmol/L) and pCO2 >6kPa
  • PaCO2 between 45 mmHg and 90 mmHg

Patients should be alert and cooperative. Ideally, they should not have excessive secretions. If there are secretions, address the issue with manual cough assistance (“breath-stacking” technique) or early fiberoptic bronchoscopy. Keep in mind that the latter has a higher risk of increased ventilatory support

If the patient has Acute CHF, look for:

  • PaO2/FiO2< 250
  • RR> 25-30
  • FiO2 (usually 28% venturi mask – aim for O2 saturation 86-90%)

CPAP (continuous positive airway pressure) and bilevel noninvasive positive pressure ventilation (NPPV) can be administered to patients who underwent abdominal, thoracic, and cardiac surgery. They have the potential to reduce intubation rates, nosocomial infections, morbidity, and mortality.

If the patient is stable, discuss their treatment with them so you can continue following their medical preferences should their condition deteriorate. 

Non-Invasive Ventilation Protocol 

Established guidelines can ensure a safe, successful procedure.

Step 1: Prepare the Patient 

Position the patient in bed or chair at a >30-degree angle.

Slowly acclimate them to BiPAP. Start by having them hold the mask over their face. Check for leaks and demonstrate the use of the quick-release strap, then initiate iPAP at 10 cmH2O and ePAP at 5 cmH2O.

Step 2: Set Ventilator Settings 

The machine will cycle between a high-pressure level (iPAP) and a low-pressure level (ePAP). Configure the settings to:

  • iPAP: 12-15 cmH20
  • ePAP: 5-8 cmH20
  • Triggers: max sensitivity  
  • Rise time (0.05-0.4 seconds)
  • Backup rate: 12-15 minutes

You can then titrate iPAP in increments of 2 to 5 cm H2O every 10 to 20 minutes. Then, titrate FiO2 to achieve SaO2 > 90% and increase ePAP to wean FiO2.

Step 3: Monitoring the Patient on NIV

Continuously check vitals—ECG monitoring, oximetry, cardiac rate, and chances in RR, HR, and blood pressure. This will enable you to quickly address any concerns before they become serious. 

  • Watch out for dyspnea.
  • Observe chest and abdominal wall movement.
  • Re-asses blood gas an hour before commencement. Continue checking at regular intervals.

Ensure patient comfort with a mask that fits properly.

You can use extracorporeal carbon dioxide removal (ECCO2R) with a double-lumen cannula (up to 13–15 Fr) to improve the blood gases.

Step 4: Weaning Criteria 

If the patient is clinically stable for >6 hours, with RR <24 bpm, HR <110 bpm, H+ <45 nmol/L, and SpO2 >88% on 4L O2 while on NIV, you can start weaning them by slowly reducing the pressure support. 

Weaning can also be performed by:

  • Allowing breaks for meals and medication
  • Considering the exclusive use of nocturnal NIV 
  • Administering controlled oxygen therapy

Continue with NIV if the treatment fails to deliver the intended results. Another option is to initiate invasive ventilation.

Describing Failed Noninvasive Ventilation

A study of 2,430 patients demonstrated a high NIV success rate (69.5%) with only 3% failure. These odds can be improved with knowledgeable clinicians who have ample knowledge of the predictors of failure.

The first 48 hours are critical. Focus on the following factors during this period:

  • Initial APACHE II score ≥21
  • Initial pH < 7.2 GCS ≤11
  • Minimal improvement pH / PaCO2 
  • Multi-organ failure
  • Failure to maintain a PaO2/FiO2 of >100 mmHg
  • No improvement in hypoxemia and acidosis
  • Presence of shock
  • Respiratory rate ≥35
  • Simplified Acute Physiology Score II (SAPS II) ≥ 35

Noninvasive ventilation failure could be due to air leaks and patient-ventilator asynchrony. These can be detected by monitoring accessory muscle use and the number of spontaneous breaths vs. ventilator-delivered breaths.

Complications To Expect and Plan For

Minor complications:

  • Conjunctival irritation
  • Sinus or ear pain
  • Gastric insufflation (especially  if iPAP>20 cmH20)
  • Nasal or sinus congestion
  • Pressure sores of nasal bridge or facial skin, affecting 10%–31% of patients

Major complications are rare. They include:

  • Hypotension
  • Pneumocephalus
  • Pneumothorax
  • Pneumomediastinum from NPPV 
  • Pulmonary aspiration

There’s also a risk of severe gastric distension, aerophagia, and sialorrhea.

Get the Experience You Need With HPC

According to a Cochrane systematic review, non-invasive ventilation can lower the rate of mortality (risk ratio [RR] 0.53, 95% confidence interval [CI] 0.36 to 0.80) and incidence of ventilator-associated pneumonia (RR 0.25, 95% CI 0.15 to 0.43) without increasing the risk of reintubation. 

The research also associated NIV with shorter ICU and hospital stays, including less time on mechanical ventilation.

Since a number of patients experience difficulties during weaning, professionals must have procedural experience and expertise to secure the best outcomes.

Hospital Procedures Consultants offers various courses that provide valuable insights into noninvasive ventilation, including the common pitfalls associated with BiPAP and CPAP. If you’re a visual learner, check out our detailed video on Noninvasive Positive Pressure Ventilation.


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