![]() The percent oxygen inhaled by the patient (FiO 2), usually ranges roughly 24–35% as the pure oxygen delivered from the cannula is diluted by entrainment of ambient air (21% oxygen). Nasal cannulae used for medical gas delivery are usually limited to delivery of 1–6 liters of flow per minute. Without humidity, the oxygenation and ventilation effects of high-flow therapy would be quickly overcome by the negative impact that dry air has on lung tissue. ![]() The higher the flow, the more important proper humidification and conditioning of the flow becomes. This constant stream of fresh gas flow creates an environment that assists exhalation effort by flushing the exhaled air out to maintain this reservoir of fresh air ready to be inhaled. This flow, being delivered though a small diameter delivery system and small-bore nasal cannula allows the flow that would traditionally move slowly through the upper airway to move quickly and maintain a constant stream of fresh gas which effectively washes out upper airway dead space. Through a nasal cannula a high-flow system delivers flows that approach (and can meet) total respiratory demand. The constant flush of the upper airway creates a reservoir that reduces room-air entrainment to such an amount that it becomes a true fraction of inspired oxygen as set by the device. Oxygenation is achieved by providing an increased FiO 2 in the air flow to the patient. People on nasal high flow feel more comfortable, less breathless, and there was little evidence of harm. However, the certainty that this result is reliable is low, as different studies were less precise than they could have been. It does however reduce the need for tracheal intubation (by 15%) and escalation of oxygenation and respiratory support. Use of nasal high flow in acute hypoxemic respiratory failure does not affect mortality or length of stay either in hospital or in the intensive care unit. As this is a non-invasive therapy, it avoids the risk of ventilator-associated pneumonia in situations where it can supplant the use of a ventilator. HFT is useful in the treatment of sleep apnea. Some patients requiring respiratory support for bronchospasm benefit using air delivered by HFT without additional oxygen. Heated humidification of the respiratory gas facilitates secretion clearance and decreases the development of bronchial hyper-response symptoms. HFT, the clinician can deliver higher FiO 2 to the patient than is possible with typical oxygen delivery therapy without the use of a non-rebreather mask or tracheal intubation. ![]() Its mechanism of action is the application of mild positive airway pressure and lung volume recruitment. The cannula improves the respiratory distress, the oxygen saturation, and the patient's comfort. High flow therapy has been successfully implemented in infants and older children. High-flow therapy has shown to be useful in neonatal intensive care settings for premature infants with Infant respiratory distress syndrome, as it prevents many infants from needing artificial ventilation via intubation, and allows safe respiratory management at lower FiO 2 levels, and thus reduces the risk of retinopathy of prematurity and oxygen toxicity.ĭue to the decreased stress of effort needed to breathe, the neonatal body is able to spend more time utilizing metabolic efforts elsewhere, which causes decreased days on a mechanical ventilator, faster weight gain, and overall decreased hospital stay entirely. Heated humidified high-flow therapy has been used in spontaneously breathing patients with during general anaesthesia to facilitate surgery for airway obstruction. Conditions such as general respiratory failure, asthma exacerbation, COPD exacerbation, bronchiolitis, pneumonia, and congestive heart failure are all possible situations where high-flow therapy may be indicated. High-flow therapy is useful in patients that are spontaneously breathing but have an increased work of breathing. Ī relevant parameter is the fraction of inspired oxygen (FiO 2). It is used in acute and chronic breathing problems, and is a suitable choice for treatment of patients with severe or critical COVID-19. The applied gas is heated to best match human body temperature (37 ☌) and humidified targeting ideal body saturation vapor pressure. Heated humidified high-flow therapy, often also high flow nasal cannula(e) or high flow nasal oxygen, is a type of respiratory support method that delivers a high flow (liters per minute) of medical gas to a patient through an interface ( nasal cannulae) intended to create a wash-out of the upper airway.
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