Noninvasive Oxygenation and Ventilation

Goals of noninvasive measures

Either short term or long term support of pulmonary function

Short Term– Hospital NC– BiPAP for acute respiratory distress

Long Term– Home O2 for chronic COPDers– CPAP for Obesity Hypoventilation Syndrome

or OSA

What goal for oxygen?

COPDers– Between 88 and 95%– PaO2 >= 60

Non-COPDers– >= 92%– PaO2 > 60

O2 Saturation vs. PaO2

40-50-60 to 70-80-90 rule

PaO2 O2 Sat

40 70

50 80

60 90

Types of NIV

Nasal Cannula Venti-Mask Non-rebreathers BiLevel CPAP

Non-Invasive Oxygenation: Achieved FiO2

Venti-Mask colors

Non-Rebreather versus Partial Non-rebreather

Non-Invasive Ventilation

BiLevel CPAP (not discussed)

Advantages to Noninvasive Ventilation No internal traumatic complications Decreased infections Less interference with communication and

swallowing Less need for sedation

Indications Well established

– COPD exacerbation– Weaning in COPD patients– Acute cardiogenic pulmonary edema– Immunocompromised patients– DNI patients

Weaker indications– Asthma exacerbations– Cystic fibrosis– Hypoxemic respiratory failure– Extubation failure

NIV and COPD RCTs have shown

– 20-50% reduced intubation rate– Improved RR, dyspnea and gas exchange– Decreased length of stay– Lowered mortality

Intubated COPD patients who have failed T “piece” trials– Should be able to breath without assistance for 5

minutes– Can tolerate levels of pressure generated by NIV– Should not be “difficult” intubations

NIV and Asthma

Physiological Rationale– Decrease work of breathing– Improve exchange

Limited evidence– No consistent recommendations for trial of NIV

in patients failing standard therapy

Acute Cardiogenic Pulmonary Edema Physiology

– Recruits “flooded” alveoli– Reduces preload and afterload

RCTs have shown that BiPAP/CPAP can– Improve dyspnea and oxygenation– Lowers intubation rate– Reduced intubation– Reduced LOS– Reduced mortality

Immunocompromised Patients

Mechanical ventilation in these patients have a high risk of– Nosocomial infection (VAP) and septicemia

– Fatal airway hemorrhage caused by thrombocytopenia and platelet dysfunction

NIV begun in these patients before respiratory failure becomes severe may halve mortality

Greatest benefit with early initiation and single-organ failure

Post-op Patients

CPAP reduces intubation in patients after abdominal surgery (reduces atelectasis)

NIV improves outcomes in hypoxemic respiratory failure after lung resection

Predictors of NIV success in acute respiratory distress Cooperative patient Intact neurological function Good synchrony with ventilator APACHE score <29 pH > 7.25 Intact dentition Air leaking well-controlled Able to control secretions

Selection guidelines for use of NIV in acute respiratory distress Appropriate diagnosis with potential

reversibility over hours to days Ascertain need for ventilatory assistance

– Moderate to severe respiratory distress– Tachypnea (>24/min for COPD, >30/min for

hypoxemia– Accessory muscle use or abdominal paradox– Blood gas abnormality– pH < 7.35, PaCO2 > 45 or PaO2/FiO2 < 200

Contraindications for NIV Respiratory arrest/Cardiac arrest Medically unstable (hemodynamically unstable,

arrythmias, cardiogenic shock/MI, GIB, ABG pH < 7.1)

Unable to protect airway (bulbar dysfunction, AMS)

Excessive secretions Uncooperative or agitated Unable to fit mask (facial trauma/surgery) Recent upper airway or GI surgery

BiLevel – What is it?

IPAP (Inspiratory Positive Airway Pressure)– Excess pressure to move air into lungs

EPAP(Expiratory Positive Airway Pressure)– Increased minimum lung pressure maintained

to increase alveolar recruitment

PS (Pressure Support)– PS = IPAP - EPAP

BiLevel – Setting?

IPAP– Usually 8-12 cm H2O

EPAP– Usually 4-5 cm H2O

BiLevel - Recheck

A baseline ABG should be done during initial episode of respiratory distress

Patient should be followed-up in 1-2 hours depending on condition after BiLevel NIV is placed

BiLevel – Recheck Criteria Objective

– Compare repeat ABG to baseline– PaO2/FiO2 should be > 150 after 1st hour– Gas Exchange: Oximetry, PaCO2, pH– RR, HR, BP, cough strength and ability to raise secretions should be

improved Subjective

– Comfort/Discomfort– Feeling of dyspnea

Ventilatory Function– Synchrony– Tidal Volume– Airleaks– Wave form

BiLevel - Complications