Walsh: Perinatal and Pediatric Respiratory Care, 3rd Edition

Chapter 18: Continuous Positive Airway Pressure

Answers to Assessment Questions and Clinical Scenarios

1.	B
Rationale: Infants are obligate nasal breathers and therefore seem to tolerate nasal prongs better. Research has shown that nasal prongs have less imposed resistance, compared with ETTs, and result in less imposed work of breathing for patients breathing through these systems.
2.	C
Rationale: There has been no research describing the effects of CPAP on mucous production; however, research has shown that the other answers are correct.
3.	A
Rationale: Infants with a preoperative diagnosis of congenital diaphragmatic hernia are typically intubated and placed on a mechanical ventilator to avoid the risk of gastric insufflation, which could result in significant compromise in these infants. Therefore, noninvasive applications for CPAP should be avoided until after surgical repair of the hernia.
4.	D
Rationale: Gastric distension can result from air entering the abdomen, which is more common when using CPAP levels greater than 10 to 12 cm H2O. Oropharyngeal leaks are more common when using CPAP levels greater than 8 to 10 cm H2O.
5.	C
Rationale: A 40% increase in FiO2, during the first 24 hours of nasal CPAP, may represent a useful clinical marker to identify infants at high risk for developing a pneumothorax. Physiologic changes associated with pneumothorax include decreased arterial blood pressure, heart rate, and respiratory rate, narrowed pulse pressure, and decreased Po2.
6.	A
Rationale: Bubble CPAP (B-CPAP) provides pressure by allowing exhalation through a fluid-filled column by inserting the expiratory tubing to the required depth. Therefore, this system does not rely on a PEEP/exhalation valve. Ventilator-derived CPAP (V-CPAP) uses this type of valve to maintain pressure in the system.
7.	D
Rationale: Early pioneers of CPAP suggested that the reason for applying CPAP was to reproduce the physiologic effects of expiratory grunting, exhibited by infants in respiratory distress, to maintain functional residual capacity (FRC). This feature was no longer apparent in infants who were intubated and they wanted to try to produce this same effect in order to improve oxygenation.
8.	C
Rationale: The proper bedside care of an infant receiving CPAP is, perhaps, the single most important aspect regarding outcomes and successful use of CPAP therapy. It has also been recognized that these improved outcomes correlate well with the level of skill, familiarity, and experience of the clinicians after implementation of a new CPAP strategy in infants. This includes caregivers who are adequately trained and are proficient at trouble-shooting and selecting the proper-sized hat and nasal prongs or mask.
9.	A
Rationale: The fixation technique is an important aspect of airway care in infants receiving CPAP support. The hat should be tight fitting, covering the ears and extending to the base of the neck. Lateral attachment of straps should provide equal and gentle tension to avoid pressure points on the skin while securing the nasal interface to the infant. The lack of stabilization and, hence, excessive movement of the prongs could result in worsening nasal injury, airway displacement, and loss of system pressure.
10.	D
Rationale: Methods using high-flow humidified nasal cannular devices in lieu of CPAP are frequently reported. Although there may be some clinical advantages regarding the use of humidified high-flow nasal cannulas, there are limited data concerning the safety of these devices in humans. The lack of monitoring of airway pressures and of means for providing a high-pressure “pop-off” mechanism raises legitimate concerns about the safe delivery of CPAP by high-flow nasal cannulas.