Heliox and Nitric Oxide
Helium-oxygen (Heliox, H-O2) mixture can be used to facilitate breathing. Due to helium’s low density, it reduces the patient’s required work of breathing (Heuer & Hilse, 2020). However, helium by itself is insufficient to maintain breathing, and is, therefore, always mixed with at least 20% oxygen (Heuer & Hilse, 2020). Heliox therapy is used for managing hypoxemia common with large airway obstructions and acute obstructive disorders, including status asthmaticus (Heuer & Hilse, 2020). Generally, heliox should be delivered through a nonrebreathing mask; high flow is critical due to the gas’ physical properties (Heuer & Hilse, 2020). Heliox may prevent the delivery of aerosols or other medications, and its low density can prevent the patient from coughing (Heuer & Hilse, 2020). Furthermore, the high flow required for the therapy to be effective may cause lung injury if used with mechanical ventilators (Heuer & Hilse, 2020)
Nitric oxide (NO) is a gas used in respiratory therapy. When inhaled, it causes the relaxation of vascular smooth muscles, which leads to improved arterial oxygenation, as well as reductions in intrapulmonary shunting, pulmonary vascular resistance, and pulmonary arterial pressure (Heuer & Hilse, 2020). Nitric oxide treatment is primarily indicated for the term and near-term infants with hypoxic respiratory failure and pulmonary hypertension (Heuer & Hilse, 2020). The dosage for neonates is 20ppm, which can be reduced after 4 hours of treatment (Heuer & Hilse, 2020). Adverse effects of NO include increased left ventricular filling pressure; additionally, withdrawing treatment has a known rebound effect (Heuer & Hilse, 2020). NO should be administered to mechanically ventilated patients at a constant concentration (Heuer & Hilse, 2020). When withdrawing from the treatment, NO concentration should be gradually reduced to avoid the rebound effect (Heuer & Hilse, 2020).
Airway Clearance Therapy
Positive expiratory pressure (PEP) and oscillating positive expiratory pressure (OPEP) are two methods of airway clearance therapy, necessary when a patient is unable to clear secretions from their airways without assistance. Chronic conditions which can cause such issues include cystic fibrosis, ciliary dyskinetic syndromes, and bronchiectasis (Vines & Gardner, 2020). Both involve controlled exhaling through a device that creates resistance to the airflow to clear secretions (Vines & Gardner, 2020). OPEP devices add an oscillating part that creates fluctuations in the airway pressure, loosening the secretions and further facilitating their clearance (Vines & Gardner, 2020). The main advantage of these types of therapy is their cost effectiveness and ability to be self-administered; however, patients need to be able to take a deep breath to use them (Vines & Gardner, 2020). In contrast, high-frequency chest wall compression (HFCWC) devices mechanically oscillate the patient’s chest wall to achieve the same goal (Vines & Gardner, 2020). These devices can be used on patients unable to provide sufficient airway pressure, but their specialized nature makes them less cost-effective and prevents self-administration (Vines & Gardner, 2020).
Lung Expansion Therapy
Spontaneous Deep Breath versus Positive Pressure Breathing
Lung expansion refers to a multitude of procedures, including PEP, high-flow nasal cannulas (HFNC), and incentive spirometry. These procedures are aimed at preventing or correcting alveolar collapse (atelectasis) and increasing the functional residual capacity of the patient’s lungs (Fisher, 2020). They fall under two categories: spontaneous deep inspiration seeks to decrease the patient’s pleural pressure while applying positive pressure to the patient’s lungs increases his or her alveolar pressure (Fisher, 2020). Both of these approaches increase the difference between the patient’s alveolar and pleural pressure (Fisher, 2020). Incentive spirometry instructs the patient to take deep breaths, but cannot be used if the patient is uncooperative or unable to breathe effectively (Fisher, 2020). Noninvasive ventilation (NIV) methods, such as continuous positive airway pressure (CPAP), HFNC, and PEP, can also be used as lung expansion therapy (Fisher, 2020). CPAP is a mechanical method suitable for patients with hypoventilation, but not those with nausea, facial trauma, or elevated intracranial pressure (Fisher, 2020). HFNC is a common way of providing supplemental oxygen to a patient (Fisher, 2020). The primary contraindication common for all lung expansion therapies is untreated pneumothorax (Fisher, 2020).
References
Fisher, D. (2020). Lung expansion therapy. In R. M. Kacmarek, J. K. Stoller & A. J. Heuer (Eds.), Egan’s Fundamentals of Respiratory Care (12th ed., pp. 936-951). Elseveir.
Heuer, A. J., & Hilse, A. M. (2020). Medical gas therapy. In R. M. Kacmarek, J. K. Stoller & A. J. Heuer (Eds.), Egan’s Fundamentals of Respiratory Care (12th ed., pp. 906-935). Elseveir.
Vines, D. L., & Gardner, D. (2020). Airway clearance therapy. In R. M. Kacmarek, J. K. Stoller & A. J. Heuer (Eds.), Egan’s Fundamentals of Respiratory Care (12th ed., pp. 952-971). Elseveir.