EMmedonline

 CRITERIA

• RR > 25 breaths/min

• Moderate to severe acidosis; pH 7.3 – 7.35

CONTRAINDICATION

• Coma

• Respiratory arrest

• Cardiac arrest

• Any condition requiring immediate intubation

• Upper airway obstruction

• Inability to clear secretion

• Facial or head surgery/ trauma

Relative contraindication

• Cardiovascular instability

• Uncooperative patient (Impaired mental status, somnolence)

• Copious & viscous secretion

• Extreme obesity

• Fixed nasopharngeal abnormality

INDICATION

• COPD : It is very effective in type 2 respiratory failure. It can reduce the rate of intubation, mortality rate & length of stay. Bipap

• Cardiogenic pulmonary oedema : Here they increase functional residual capacity, recruitment of alveolar lung units, improving ventilation/ perfusion relationships & gas exchange. Positive intrathoracic pressure decreases transmural systolic left ventricular pressure which reduces after load to left heart improving left ventricular emptying and cardiac output. Reduction in venous return also decreases preload. CPAP is better than Bipap.

• Post extubation period : NPPV is effective in reducing work of breathing in the post extubation period.

• Pneumonia : NIMV helps to improve oxygenation & relief of dyspnea but there are concerns of hemodynamic instability, secretion clearance & refractory respiratory failure.

OTHER CONDITIONS

• Immunocompromised patients : Selected patients may be benefited.

• Asthma: Studies are promising & found more rapid & greater improvement in lung function as well as lower hospitalisation rates.

• ARDS : Mild cases can be managed with NIMV.

• DNI

• Rib fracture/ Chest wall trauma

• Cystic fibrosis, OSA, Pneumocystis carinii pneumonia, kyphoscoliosis , neuromuscular disease

How does NIV help?

• Reduces the work of breathing

• Increases lung volume

• Increases functional residual capacity.

• Redistribution of pulmonary fluid from alveolar space to extra alveolar tissue.

• Preload & after load are decreased thereby improves cardiac function.

• They reverses hypoventilation by increasing tidal volume & minute volume.

Types of NIV

• BiPAP : Bilevel positive airway pressure

• CPAP Continous positive airway pressure

• NIV in ventilators : Both pressure support & control modes are available.

How to initiate ?

• A goal of 5-7 ml/kg TV has to be achieved with additional support to maintain respiratory rate <25 bpm.

• Initiate with a IPAP of 10 cm H₂0 & EPAP of 5 cm H₂O.

• Maximum inspiratory pressures should be limited to about 20-25 cmH₂O.

• NIV is best delivered in 3 to 4hrs block with 30 -60 min breaks.

• Hypoxemic patients are best treated with an increase in the PEEP (CPAP) or EPAP with a proprotionate increase in IPAP.

• Hypercapnic patients benefits best from increasing tidal volume as a result of increase in IPAP.

COMPLICATION

• Pressure injury & skin necrosis

• Nasal congestion

• Sinusitis

• Gastric distension

• Eye irritation

Note : Restrictive lung disease (ILD) is the only condition where inverse ratio ventilation is used.