5. Acute Respiratory Failure Flashcards
Acute Respiratory Failure is defined as
a RAPIDLY occurring inability of the lungs to maintain adequate oxygenation of the blood with or without impairment of carbon dioxide (CO2) elimination.
Specifically, the ABG demonstrates:
PaO2 of 60 mmHg or less, with or without an elevation of PaCO2 to 50 mmHg or more with pH <7.30
The primary problem of Acute Respiratory Failure may be
one of hypoxemia (type 1) or hypercarbia (type 2) or both (type 3)
Type 1 (hypoxemic)
-ARDS
-Asthma
-Atelectasis
-Interstitial fibrosis
-Pneumonia
-Pulmonary edema (heart failure)
-Pulmonary embolism (massive)
-Smoke inhalation
Type 2 (hypercapnia)
-CNS depression due to oversedation
-COPD (acute exacerbation)
-Head trauma
-Musculoskeletal disorders or trauma
-Sleep apnea
-Status asthmaticus
Type 3:
-ARDS (late)
-COPD (late, acute exacerbation)
-Status asthmatics (late)
Clinical signs and symptoms of acute HYPOXEMIC Respiratory Failure
-Pulmonary: tachypnea, adventitious breath sounds,
accessory muscle use.
-Cardiac: tachyarrhythmias (initial), bradyarrhythmias
(late), hypertension or hypotension, cyanosis (central,
eg: lips, earlobes)
-Neurological: anxiety, agitation
Clinical signs and symptoms of acute HYPERCAPNIC Respiratory Failure
-Pulmonary: shallow breathing, bradypnea, lungs may
be clear or there may be adventitious breath sounds
-Neurological: progressive decreased level of
consciousness (lethargic, obtunded, stuporous,
unresponsive).
Acute Respiratory Failure ID & trmt:
Prompt identification and treatment may prevent a catastrophic outcome! The etiology of the signs/symptoms may not be the primary focus initially.
Treatment of Acute Respiratory Failure
-Maintain airway and improve ventilation
-Optimize Oxygenation
-Optimize circulation, cardiac output
-Identify etiology: target treatment accordingly
-Provide emotional support
Ways to maintain airway and improve ventilation in Acute Respiratory Failure
-Positioning (upright)
-Suctioning
-Bronchodilator therapy for wheezing
-Noninvasive ventilation
-Intubation, mechanical ventilation if needed
-Repeat ABGs as needed
Ways to optimize oxygenation in ARF
-Adjust FiO2 to keep SaO2 ~ > 0.90
-Decrease FiO2 to 0.50 or less ASAP
-Do not allow hypoxemia to occur to “prevent O2 toxicity”
-Use PEEP/CPAP as needed
-Use pulse oximetry to monitor response to therapy
Ways to Optimize Circulation, Cardiac Output in ARF
-Manage hypotension
-Address Cardiac Arrhythmias
Use of Noninvasive Ventilation for the Management of Acute Respiratory Failure
When used for an appropriate pt, noninvasive ventilation (NIV) has been shown to decrease morbidity and mortality. There are 2 main types of NIV (exam doesn’t cover details related to type of NIV). Instead, understand those who would NOT benefit from this therapy. Occasionally, a pt may initially be a good candidate for NIV but then, due to a change in condition, the pt should be intubated with an ETT.
2 types of NIV
CPAP & BiPAP
CPAP
Continuous Positive Airway Pressure
-Indicated for pts with hypoxemic respiratory failure who have increased work of breathing (e.g., cardiogenic pulmonary edema)
-Settings include FiO2 and 1 pressure setting in cm H2O pressure.
BiPAP
Bilevel positive airway pressure
-Indicated for pts with hypoxemic and/or hypercapnia respiratory failure
-Settings include FiO2 and 2 pressure settings: the inspiratory positive airway pressure (IPAP) and the expiratory positive airway pressure (EPAP).
-IPAP assists ventilation and EPAP assists oxygenation.
Advantages of NIV
-Buys time for medical treatment to take effect
-Reduces the work of breathing (WOB)
-Decreases preload and afterload
-Improves Oxygenation
-Improves ventilation (BiPAP)
-Reduces atelectasis
-Prevents intubation and resultant risks
Contraindications for NIV
-Hemodynamic instability or life-threatening arrhythmias
-Copious secretions
-High risk of aspiration
-Impaired mental status (unable to protect airway)
-Suspected pneumothorax
-Inability to cooperate
-Life-threatening refractory hypoxia (PaO2 < 60 with FiO2 1.00)
HFNC
High-Flow Nasal Cannula (HFNC) Oxygen, which has long been used for pediatric and infant pop., is now used for select adult populations in the treatment of acute respiratory failure and post-extubation
HFNC oxygen delivery systems are able to deliver ___
FiO2 (up to 100%) of heated and humidified gas at flow rates up to 60 L/min via a nasal cannula
Advantages of HFNC therapy
-Able to provide high FiO2 (up to 100%)
-Heated and humidified oxygen may improve secretion clearance and decrease airway inflammation
-Able to meet high inspiratory flow demands of tachypneic pts
-seems to promote alveolar recruitment and increase FRC
-Decreases dead space ventilation
-more comfortable than CPAP or BiPAP masks, allows access to the mouth without removal of a mask
Limitations of HFNC therapy
-Unable to deliver higher airway pressures (PEEP or CPAP), and the low levels of airway pressure provided are variable when mouth breathing
-Provides limited pressure support for a pt with hypercapnia respiratory failure
Indications of HFNC therapy:
-Community-acquried pneumonia
-Cardiogenic pulmonary edema when NIV is not tolerated
-Preoxygenation prior to intubation
-Post-extubation (even in low-risk pts)
-For a pt who refused intubation (DNI) but accepts alternate treatment measures
-HFNC oxygen therapy may also be used in conjunction with NIV post-extubation to prevent re-intubation
Nursing implications for HFNC therapy:
-Monitor for deteriorating oxygenation/ventilation (the pt may require NIV or intubation and mechanical ventilation)
-Assess for nasal skin irritation.
