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KEY CONCEPTS
Hyperoxia and hypoxia are risk factors for but not the primary causes of retinopathy of prematurity (ROP). Neonates’ risk of ROP increases with low birth weight and complexity of comorbidities (eg, sepsis).
The disadvantage of conventional PCV is that tidal volume (VT) is not guaranteed (although there are modes in which the consistent delivered pressure of PCV can be combined with a predefined volume delivery).
Pressure control ventilation (PCV) is similar to pressure support ventilation in that peak airway pressure is controlled but is different in that a mandatory rate and inspiratory time are selected. As with pressure support, gas flow ceases when the pressure level is reached; however, the ventilator does not cycle to expiration until the preset inspiration time has elapsed.
Both nasotracheal and orotracheal intubation appear to be relatively safe for at least 2 to 3 weeks.
When left in place for more than 2 to 3 weeks, both orotracheal and nasotracheal tubes predispose patients to subglottic stenosis. If longer periods of mechanical ventilation are necessary, the tracheal tube should generally be replaced by a cuffed tracheostomy tube.
The major effect of positive end-expiratory pressure (PEEP) on the lungs is to increase functional residual capacity (FRC). In patients with decreased lung volume, appropriate levels of either PEEP or continuous positive airway pressure (CPAP) will increase FRC and tidal ventilation above closing capacity. This will improve lung compliance and will correct ventilation/perfusion abnormalities.
Compared with a VT of 12 mL/kg, a VT of 6 mL/kg and plateau pressure (Pplt) less than 30 cm H2O have been associated with reduced mortality in patients with acute respiratory distress syndrome.
A higher incidence of pulmonary barotrauma is observed with excessive PEEP or CPAP at levels greater than 20 cm H2O.
Maneuvers that produce sustained maximum lung inflation, such as the use of an incentive spirometer, can be helpful in inducing cough as well as preventing atelectasis and preserving normal lung volume.
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Respiratory care includes both the delivery of pulmonary therapy and performance of diagnostic tests. Respiratory therapists’ scope of practice encompasses medical gas therapy, delivery of aerosolized medications, airway management, mechanical ventilation, positive airway pressure therapy, critical care monitoring, cardiopulmonary rehabilitation, and the application of various techniques collectively termed chest physiotherapy. The latter includes administering aerosols, clearing pulmonary secretions, reexpansion of atelectatic lung, and preserving normal lung function postoperatively or during illness. Diagnostic services may include pulmonary function testing, arterial blood gas analysis, and evaluation of sleep-disordered breathing. These procedures and services are well described in clinical practice guidelines developed by the American Association for Respiratory Care.
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Therapeutic medical gases include oxygen at ambient or hyperbaric pressure, helium–oxygen mixtures (heliox), and nitric oxide. Oxygen is made available in high-pressure cylinders, via pipeline systems, from oxygen concentrators, as well as in liquid form. Heliox is occasionally used to ...