Approach
Treatment goals include support of the role of the respiratory system in oxygenating and removing carbon dioxide from the blood and tissues, while the underlying cause of respiratory failure is controlled or removed.
Bridging treatments such as supplemental oxygen delivery, noninvasive ventilatory support, and mechanical ventilation are employed to support respiration while treating the underlying cause.
An Airway, Breathing, Circulation, Disability, Exposure (ABCDE) assessment is the first step of management for all patients, and should be reassessed regularly throughout treatment. Rapid deterioration, vital organ compromise, and/or loss of the airway/gag reflex indicates the need for endotracheal intubation.
Supplemental oxygen delivery for hypoxic patients
This should be administered as part of, or immediately after, the initial ABCDE assessment. Patients (conscious or unconscious) with spontaneous respiration and intact airways can be maintained on supplemental oxygen providing there is no vital organ compromise and the airway/gag reflex remains intact.
Provision of supplemental oxygen by nasal cannula, mask, or noninvasive (positive pressure) ventilation (NIV) is important for the initial treatment of hypoxia when imminent respiratory arrest is not at issue. When tolerated, high flow oxygen by nasal cannula may be as effective as mask delivery. [47][48][49] The American College of Physicians recommends using high-flow nasal oxygen rather than NIV in the initial management of acute respiratory failure, but the evidence for this recommendation is of low certainty.[22][50]
The most tolerable, least patient restrictive method of delivering supplemental oxygen sufficient to maintain oxygen saturation (as monitored by continuous pulse oximetry and arterial blood gas analysis) should be used. NIV may be recommended for patients who are awake and conscious, and should be used with extreme caution.[22]
Care is required when providing supplemental oxygen to patients with COPD and chronically elevated carbon dioxide partial pressures, as these patients are dependent on central oxygen receptors detecting hypoxemia to drive ventilation. Acutely increasing blood oxygen levels in these patients can lead to respiratory depression. One systematic review of acutely ill adult patients (patients with chronic respiratory disease excluded) reported increased mortality among those who received liberal oxygen supplementation, compared with those who received conservative oxygen supplementation.[51] A target capillary oxygen saturation (SpO₂) range of 94% to 96% was suggested for all patients with critical illness.[51]
Obstructed airway (revealed by ABCDE assessment)
If the ABCDE assessment reveals airway obstruction, the airway must be cleared to ensure that the upper airway is open for ventilation. Direct laryngoscopy or bronchoscopy may be required to clear an airway foreign body. Emergency cricothyroidotomy or tracheostomy may be needed to manage structural obstructions at the glottic or infraglottic level. Acute treatment may be required to reduce the swelling of an airway blocked due to anaphylaxis.
No acute upper airway obstruction: spontaneous respiration, intact airway (revealed by ABCDE assessment), and otherwise stable
Patients with spontaneous respiration and intact gag reflexes, and without rapid deterioration or vital organ compromise, are maintained on supplemental oxygen. If supplemental oxygen therapy is unsuccessful, intubation and mechanical ventilation are necessary. However, NIV can be tried first in conscious, spontaneously breathing patients if this has not been attempted.[52]
NIV can be administered by continuous positive airway pressure (CPAP) or bi-level positive airway pressure (BiPAP). Both forms deliver oxygen using a tight-fitting mask and can improve oxygenation by opening previously closed alveoli. The involvement of tight-fitting masks means some patients are unable to tolerate NIV. Complications include gastric distension with decreased diaphragmatic motion and secondary vomiting, pressure ulcers around the area of the tight mask fit, and pneumothorax.[53] Hyperinflation of the lungs secondary to air trapping in the alveoli and airways can lead to a compromise of ventilatory effectiveness. There is no evidence to suggest increased intrathoracic pressure causes a decrease in cardiac function.[54]
The use of BiPAP or CPAP is favored in the management of respiratory failure secondary to acute congestive heart failure as they are not associated with a significant decrease in cardiac output. Furthermore, BiPAP and CPAP are both associated with improved short-term physiologic parameters and improved survival in the acute care setting.[55] Patients being maintained by CPAP may not require endotracheal intubation if underlying respiratory system abnormalities are reversed quickly. However, studies of emergency CPAP use for both hypoxic and hypercapnic respiratory failure have failed to show a decrease in mortality for these patients.[56]
There is evidence to suggest that BiPAP is particularly effective for management of hypercapnic respiratory failure.[57]It works by providing a specific inspiratory positive pressure that augments inspiratory effort and a low-pressure resistance for exhalation.
Contraindications for NIV in hypercapnic respiratory failure are facial deformity such that mask fitting is not possible, facial burns, and fixed upper airway obstruction.[53] Relative contraindications for use of NIV in hypercapnic patients include serum pH <7.15, pH <7.25 with adverse features (e.g., presence of copious secretions), Glasgow Coma Scale (GCS) score <8, confusion/agitation, or cognitive impairment.[53]
There is no evidence for a lower limit of pH below which a trial of NIV would be inappropriate, although the lower the pH the greater risk of failure. NIV does not provide adequate ventilatory support for patients presenting in acute respiratory failure with low GCS scores (<8 is a relative contraindication) and respiratory acidosis that do not improve within 1 hour of initiating the procedure.[58] Patients must be very closely monitored with rapid access to endotracheal intubation and invasive ventilation if needed.[22][59]
For asthma patients with altered mental status or exhaustion, immediate endotracheal intubation and ventilatory support should be considered.[60] More evidence is needed before recommending the initial use of NIV for acute asthma patients with respiratory failure.[60][61][22]
No acute upper airway obstruction: loss of gag reflex, rapid deterioration, or vital organ compromise (revealed by an ABCDE assessment)
Intubation and mechanical ventilation is required in conscious or unconscious patients when there is progressive hypoxia or hypercapnia (to the degree that vital organs are compromised and respiratory acidosis cannot be corrected) or when the airway/gag reflex is lost. It is performed to protect the airway and reduce the risk of aspiration. Intubation is often required in the emergency setting when other less-invasive ventilation efforts have failed and patients are rapidly deteriorating. The American College of Emergency Physicians provides guidance on airway management through mechanical ventilation.[62]
Endotracheal intubation and mechanical ventilation
Endotracheal intubation allows for partial or complete control of ventilatory function and suctioning and clearing of the upper airway to enhance airflow. Mechanical ventilation allows for control of airway pressures, volumes of inspiration, and rate of breathing. Invasive ventilation using mechanical ventilators is the most controlled method to manage respiratory failure.
How to insert a tracheal tube in an adult using a laryngoscope.
How to use bag-valve-mask apparatus to deliver ventilatory support to adults. Video demonstrates the two-person technique.
Intubation with mechanical ventilation controls the timing and rate of inspiration and expiration to maximize oxygen delivery. Intubation with mechanical ventilation also allows for special positioning of patients to optimize blood flow and alveolar ventilation.[66] Prone positioning is sometimes used[67] and may be particularly useful for severely hypoxemic patients, but the efficacy of the technique in lowering mortality is controversial.[68][69][70]
While intubation with mechanical ventilation will often stabilize a patient with respiratory failure, it is important to realize that the procedure is a temporizing therapy to allow for correction or reversal of the underlying cause of respiratory failure. Symptom assessment should also be carried out regularly throughout treatment in critically ill patients, including those who are mechanically ventilated. The American Thoracic Society provides guidance on how to facilitate communication with mechanically ventilated patients as a key component of symptom assessment.[71]
Initial mechanical ventilator settings are typically set for an adult tidal volume at 8 to 10 mL/kg and ventilatory rate of 12 to 14 breaths per minute. Positive end expiratory pressure (PEEP) applied with mechanical ventilation opens previously closed alveoli to improve lung function.[45]
Intubation can be facilitated in patients with intact upper airway reflexes and muscle tone (conscious or unconscious) using rapid sequence induction of anesthesia (with sedatives and paralytics). This is commonly used prior to endotracheal intubation. Rapid sequence induction of anesthesia is recommended for use by those who are experienced with intubation, as the medications used will cause loss of respiratory reflexes that can result in massive aspiration of oral and gastric contents.
Endotracheal intubation with mechanical ventilation has a number of potential complications. Secondary pneumonia, reported to occur in 9% to 27% of patients, is often with antibiotic-resistant organisms.[72][73] Barotrauma to small airways and alveoli can lead to a pneumothorax and/or pneumomediastinum, resulting in secondary respiratory compromise. Air trapping in the airways and alveolar distension can also cause decreases in venous return to the right side of the heart, which results in a drop in cardiac output and perfusion. Atelectasis or partial collapse of lung tissue may result with intubation when the endotracheal tube is malpositioned (positioned in the right mainstem bronchus) or mucus plugs or blood clots develop and block the endotracheal tube or intermediate and small airways. With endotracheal intubation there is a constant risk of displacement of the endotracheal tube with subsequent loss of the airway.
Most modern endotracheal tubes are designed to limit damage to delicate airway tissues, but prolonged need for mechanical ventilation may require tracheostomy because use of an endotracheal tube for >5 to 7 days can lead to tracheal inflammation and subsequent stenosis. In addition, the teeth and vocal cords can sustain damage during insertion of an endotracheal tube.
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To decrease the length of time and sedation required for ongoing endotracheal intubation and mechanical ventilation for patients with chronic hypercapnic respiratory failure, noninvasive Bi-PAP or CPAP ventilation may be a reasonable weaning strategy.[74]
Treatment of underlying causes for all patients
Investigation of the underlying cause usually begins as part of the ABCDE assessment (with ABG, intravascular catheterization, and blood sampling). Further investigations, such as chest x-ray and ECG, are done at later stages. Treatment of the underlying cause of respiratory failure is essential and is started as early as possible after the cause is known. Mechanical ventilation may momentarily stabilize respiratory failure, but the underlying cause must be controlled or treated to ensure reversal.
Treatment may include antibiotic therapy for infection, epinephrine for anaphylaxis, opioid reversal with naloxone, bronchodilation/corticosteroid therapy for chronic lung disease, decompression/chest tube insertion for pneumothorax, fluid resuscitation for hypovolemia, thrombolysis/embolectomy for pulmonary embolus, radiation therapy for malignancy, and surgery for trauma or malignancy.
How to insert an intercostal (chest) drain using the Seldinger technique. Video demonstrates: how to identify a safe site for insertion; use of an introducer needle, guidewire, dilators, and intercostal drain; how to confirm drain position; and postprocedure care.
How to size and insert a laryngeal mask airway.
How to select the correct size naspharyngeal airway and insert the airway device safely.
How to size and insert an oropharygeal airway.
How to use a pocket mask to deliver ventilation breaths to an adult patient.
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