Oxygen Saturation Monitoring

It is important that neonates receiving respiratory support have their oxygen status monitored on a continuous basis. The optimal oxygen saturation targets in premature infants have not been definitively determined and are usually set by unit protocol. Reducing the targeted oxygen saturation ranges in premature infants to between 85% and 93% substantially decreased rates of grades III and IV retinopathy of prematurity. The SUPPORT Trial found a small but statistically significant increase in early deaths in the group of infants in the lower oxygen saturation range. This has prompted some experts to recommend keeping oxygen saturations above 90% in the early neonatal period until more definitive data are available. Similarly the BOOST-II trial, which enrolled 2108 infants born at less than 28 weeks’ gestation before enrollment was stopped, demonstrated a significant increase in the combined outcomes of death and disability at 2 years of age in neonates randomized to an oxygen saturation target range of 85% to 89% compared to those in the target range of 91% to 95% (BOOST-II Australia and United Kingdom Collaborative Groups, 2016). The authors of a meta-analysis of the SUPPORT, the COT (Canadian Oxygen Trial), and the three BOOST-II studies concluded that an oxygen saturation target range of 90% to 95% should be used until further data become available.

Target saturation levels are also dependent on the infant’s underlying condition and the goals of care. In infants with persistent pulmonary hypertension, it may be desirable to maintain a higher oxygen saturation level, whereas in those infants with cyanotic congenital heart disease, a target saturation as low as 75% may be acceptable.

Maintaining tight control of oxygen levels presents a significant challenge for clinicians. Among the challenges is the significant lability displayed by ventilated premature infants related to their disease conditions, responses to environmental stimuli, and need for ongoing interventions such as suctioning and other invasive procedures. Education and awareness regarding the need for narrow oxygen target ranges is also a challenge. A multicenter audit found that nurses were compliant with pulse oximetry alarm limits around 70% of the time. Another multicenter study reported that, although lower alarm limits were set correctly 91% of the time, higher alarm limits were set correctly only 23% of the time, with 76% of the limits set too high and 24% of the limits set at 100%. In 2013, The Joint Commission issued a sentinel alert statement related to medical device alarm safety that highlighted the potential danger of alarm fatigue, a problem familiar to those responding to repeated oxygen saturation alarms.

A number of successful quality improvement projects designed to address oxygen targeting and alarm fatigue have been reported. One of the early reports came from Chow and colleagues, who developed an oxygen targeting policy followed by an extensive staff education and audit process. The authors describe an initial resistance to change among staff, difficulties in consistency in implementation on different shifts, and the need for initial training, followed by retraining. Since Chow and colleagues reported on the results of their initiative, many NICUs have undertaken similar quality improvement projects to remind staff of the need to carefully monitor oxygen saturation and maintain much tighter control of parameters, avoiding hyperoxia in infants at high risk of retinopathy of prematurity ( Fig. 28-1 ). Carefully evaluating the number and types of procedures that a ventilated neonate receives is also necessary to reduce episodes of hypoxia and resulting hyperoxia when increased FiO ₂ is administered.

Pulse oximetry sign.

Positioning and Containment

Premature and seriously ill neonates undergo a significant number of hands-on assessments or procedures in a 24-hour period. A descriptive study showed that infants averaged eight painful procedures per day during the first 2 weeks of NICU stay; the authors encouraged neonatal units to question the need for each and every potentially harmful invasive procedure.

Procedures often result in significant and prolonged reductions in oxygenation. The extent of hypoxemia and overall distress can be dramatically reduced when personnel modify their caregiving according to the infant’s responses. Careful observations of oxygenation and behavioral reactions in infants receiving CPAP or mechanical ventilation with appropriate, individualized interventions can reduce the amount of stress the infant experiences. Many NICUs are moving to provide cue-based care, that is, providing routine care to the infant only during times when the infant is awake.

Supporting the infant’s body position can also reduce the stressful effects of procedures and other interventions. Swaddling, rolls, and the use of other containment techniques have been shown to improve physiologic and behavioral organization during weighing, suctioning, and heel sticks and provide comfort from pain. Placing an infant on assisted ventilation in the prone position increases oxygenation, improves sleep, and reduces stress compared to the supine position, possibly by increasing lung volumes and residual capacities. The Cochrane review of 12 trials (285 infants) comparing various positions for ventilated infants found that prone positioning slightly improved oxygenation, but that there was no evidence of sustained improvement for infants who were positioned prone. One study found lower bacterial colonization in infants who were cared for in an alternating lateral position compared to those neonates cared for in a supine posture.

Infant positioning is also a risk factor for the development of intraventricular hemorrhage. In an evidence-based review of the literature on midline head positioning, Malusky and Donze identified 11 articles that met the inclusion criteria for the review. Despite some differences in the study populations and methods of evaluation, several studies found changes in cerebral blood flow with position changes. Three studies found a significant decrease in intracranial pressure when infants were positioned with their heads in midline. The authors of this review concluded that there was support for maintaining infants <32 weeks in a midline (neutral) head position with the head of the bed elevated 30 degrees for the first 72 hours of life.

Nasal Continuous Positive Airway Pressure

One of the key strategies in preventing barotrauma and chronic lung disease is avoiding endotracheal tube-mediated mechanical ventilation. As a result of this shift away from intubation, the use of noninvasive ventilation strategies including nasal CPAP (NCPAP) has increased dramatically. Caring for an infant receiving CPAP is challenging. A major factor contributing to success or failure with NCPAP lies in the comfort level and knowledge of the team providing the care. One study reported significant improvements with the success of early NCPAP over a 4-year period, indicating a substantial learning curve for all professionals involved, including nurses, respiratory therapists, and physicians; extensive and ongoing education included information on how and why CPAP works and on complications and troubleshooting.

Assessment of infants on NCPAP also includes overall evaluation of respiratory status including retractions and respiratory effort, breath sounds, oxygenation, and P co ₂ levels. Although there may be retractions and P co ₂ levels in the range of 45 to 65 torr, if the infant generally appears comfortable, he or she can be maintained on NCPAP. Signs of distress include P co ₂ greater than 65, FiO ₂ requirement greater than 60% consistently, and increased retractions, tachypnea, and apnea. These signs may be indications that the infant is failing NCPAP and that noninvasive ventilation or intubation plus assisted ventilation is needed. Assessment of an infant on CPAP includes careful assessment of the cheeks, philtrum, and nasal structures for any evidence of redness, erythema, or injury.

Complications from NCPAP include airway or prong blockage by secretions, and injury to the skin and nasal septum, abdominal distension, feeding intolerance, and a slight increase in the risk of pneumothorax and necrotizing enterocolitis. Careful auscultation of breath sounds is needed, as well as attention to the pressure limits on the CPAP delivery device. Excessive abdominal distension is addressed by gastric decompression with an orogastric tube, although this complication may often hinder the advancing of enteral feedings and lead to numerous abdominal X-rays. One study documented that gastric emptying actually occurred earlier in infants receiving NCPAP.

Maintenance of continuous flow and appropriate CPAP pressures is affected by the infant’s position and overall comfort. The prongs or mask interface need to be properly positioned, and the infant’s mouth needs to be closed to ensure the maintenance of appropriate CPAP levels. To reduce the risk of the infant developing atelectasis, avoid removing the mask or prongs for routine care in the first 24 to 48 hours and minimize the disruption of CPAP as much as possible until the infant is ready for weaning.

One of the biggest challenges encountered while caring for the infant on NCPAP is protecting the nasal septum and surrounding structures from injury. Nasal injury is more common in more premature infants and in those infants requiring CPAP for long periods of time. Types of nasal injury include nasal snubbing, flaring or widening of the nares, and necrosis of the columella nasi. The nasal septum is fragile, and the interfaces between the infant’s nose and the CPAP system, either prongs or mask, may cause pressure on facial structures. There are limited data about the effect of using CPAP masks in premature infants, although many NICUs have adopted the use of masks alternating with nasal prongs in an effort to reduce nasal trauma. Diligence in ensuring the appropriate positioning of prongs relative to the nose and frequent repositioning is necessary. The CPAP hat should fit snugly and should rest just above the infant’s eyebrows. Prongs should be the correct size to fit snugly in the nares without excessive pressure on the septum and should be positioned to avoid blanching of the skin around the nose. Straps should be snug but not to the point of creating indentations on the cheeks.

Despite meticulous care practices, tissue injury may occur on the philtrum of the lip or the nasal septum ( Fig. 28-2 ). Hydrocolloid “shields” have been shown to offer some protection against injury but do not prevent all injuries because pressure is often the problem, rather than friction. Once the skin barrier has been injured, use of these products may promote further breakdown. Application of an antimicrobial ointment such as mupirocin may be beneficial to reduce the risk of infection through this portal of entry.

Damage caused by nasal CPAP.

Administration of oxygen under pressure through nasal prongs can be excessively irritating to nasal mucosa, resulting in increased production of secretions, especially in the first few hours after initiation. The use of warmed, humidified gas is imperative. Although there is currently no empirical evidence for exactly how best to care for the airway of infants on NCPAP, suctioning of the nares to maintain patency is required. Suctioning should be based on assessment of the patient and not routinely scheduled. Frequent suctioning causes trauma to the nares and nasopharynx and may increase the risk of infection through skin breakdown. Other hazards of suctioning include bradycardia or cardiac dysrhythmias. Using techniques such as round-tipped plastic suction devices can minimize trauma from mucosal bleeding and swelling. Saline or sterile water drops instilled prior to suctioning may be helpful in loosening secretion and lubricating the catheter.

Repositioning is essential for a number of reasons, including neurodevelopmental outcomes, and is recommended every 4 to 6 hours. Prone positioning may also be beneficial in infants receiving NCPAP because lying prone seems to aid in keeping the infant’s mouth in a closed position, decreases abdominal distension, and also keeps the infant calmer. Offering a pacifier and providing containment using swaddling or nesting techniques can be beneficial in both promoting comfort and improving respiratory support. The use of a chin strap may prevent air leaks and loss of CPAP pressure.

Mechanical Ventilation

There are a wide variety of neonatal ventilators in the market, each with a unique set of properties and settings. Everyone providing care to the infant on mechanical ventilation should have an understanding of the machine itself and the interface between the machine and the baby. Careful assessment of the infant’s breathing pattern, chest movement, respiratory rate, and oxygenation should be undertaken each shift and each time ventilator parameters are adjusted. This information is then documented in the patient record along with any diagnostic tests (X-rays or blood gases) that are performed. There are some issues unique to mechanical ventilation that should be considered in the care of the infant. These include airway security, endotracheal tube (ETT) movement and position, suctioning of the ETT, and prevention of ventilator-acquired pneumonia.

Endotracheal Tube Movement and Malposition

The position of the ETT may be altered with inadequate fixation of the tube, changes in patient position, and flexion and extension of the head. Because the trachea of a term newborn is quite short (mean 57 mm) and even shorter in premature infants, small movements of the ETT can result in displacement, causing the tube to move into the right main stem bronchus with flexion or into the neck with extension ( Fig. 28-3 ). In addition to potentially altering ventilation and blood gas parameters and causing tracheal damage, ETT movement can result in misinterpretation of the ETT position on X-rays. The infant’s head should be carefully positioned when obtaining X-rays and placed in a “neutral” position to avoid extension or flexion. The ETT should be positioned with the bevel opening to the same side the head is facing to avoid having the bevel abut against the tracheal wall with head movement or position changes ( Fig. 28-4 ).

X-rays showing endotracheal tube position changes with head position changes.

Endotracheal tube bevel.

Each NICU should develop a standard practice that is consistently used to avoid confusion during intubations and ETT retaping. A card specifying the depth at which the ETT is inserted should be posted at each bedside, with the centimeter marking that is at the patient’s lip displayed. Adhesion of the ETT taping should be inspected often and the ETT retaped whenever necessary to prevent accidental dislodgment. Regular monitoring of unplanned extubations can be incorporated into quality improvement audits.

Suctioning

The presence of an ETT causes irritation to tissue and increased secretions. It is necessary to clear this artificial airway periodically to maintain ventilation for the infant. ETT suctioning has been associated with a number of complications in infants including hypoxemia, bradycardia, atelectasis, airway trauma, and pneumothorax. Systemic adverse effects are also of concern, including increased blood pressure, changes in intracranial pressure, and an increased risk of infection. Neonates should be suctioned only when it is assessed to be needed, that is, when breath sounds are moist or congested, when secretions are visible, when there is a change in the infant’s respiratory rate and pattern, or when the infant is bradycardic, hypoxic, or agitated with no known cause. During high-frequency oscillatory or jet ventilation, it is not always obvious when suctioning is needed, and some nurseries implement routine suctioning every 4 to 8 hours for patients on high-frequency ventilation (HFV).

To reduce trauma to the tracheal mucosa, the suction catheter should be inserted to a premeasured depth that includes the ETT and the adaptor. Normal saline has been used for many years to lubricate the ETT; however, there is concern that saline interferes with the innate immune properties in the airway mucosa. Other studies report potential adverse effects of saline instillation on oxygenation and a potential to exaggerate complications of suctioning such as changes in intracranial pressure, trauma to the airway mucosa, and bradycardia. In addition, there is concern that saline instillation does not lead to increased secretion recovery and may be a risk factor in ventilator-associated pneumonia by way of moving the biofilm that occurs in the ETT further into the distal airway. Given the potential for adverse effects and a lack of evidence supporting the benefit of routine nasal saline instillation, this practice is not recommended.

Suctioning techniques have also been examined in an attempt to determine the least harmful method of suctioning. Cone and colleagues compared routine suctioning with a two-person procedure. They found that the use of four hands for suctioning resulted in an increase in oxygen saturation during the observation period compared to presuctioning levels and that infants displayed more stress and defensive behaviors after routine one-person suctioning compared to four-handed suctioning.

Closed suctioning (CS) systems that are placed inline with the ETT and ventilator circuit are now used in many nurseries ( Fig. 28-5 ). The research comparing open and closed suctioning practices has not been definitive in determining which system is more advantageous. A Cochrane review evaluated four studies using a crossover design that included 252 infants and found a reduction in the number and severity of hypoxic events and a decrease in the number and severity of bradycardia with CS. The authors concluded, however, that the evidence was not strong enough to recommend CS as the only acceptable method for suctioning ventilated neonates. Other potential advantages to CS include ease of use, with only one person needed, and reduced loss of lung volumes during suctioning. One study of CS in intubated adults reported that loss of lung volume during CS was reduced compared to open-system suctioning but that end-expiratory lung volumes recovered more slowly in patients suctioned with a closed system vs those suctioned with an open system. This suggests that closed systems may not be totally protective of lung volumes.

Closed suctioning.

High-Frequency Ventilation

Nursing care for the infant on HFV, either via oscillator or via jet ventilators, requires a unique set of knowledge and skills. Assessment of the infant receiving HFV is frequent and extensive, differing from routine nursery assessment related to the absence of tidal breathing. Auscultation is aimed at detecting changes in the pitch of breath sounds, with high-pitched sounds suggestive of secretions. It is not possible to auscultate the apical pulse or to detect the presence of a heart murmur while the infant is on HFV. Observing and palpating for chest vibration and other parameters of ventilation adequacy are employed. In many cases, the infant’s condition while undergoing HFV can change very rapidly because of both the infant’s underlying pulmonary pathology and the device in use. It is possible to interrupt or pause the ventilator briefly during the assessment process to auscultate spontaneous breath sounds and listen for heart murmurs; however, this can also destabilize the infant. Coordination among multidisciplinary team members is recommended for these assessment periods, so that the time during which the patient is removed from HFV is kept to a minimum.

CS should be used to prevent disconnecting the infant from ventilation during suctioning. Many NICUs use in-bed scales, weigh infants infrequently, or simply do not weigh patients receiving HFV to prevent destabilizing the respiratory system or accidental extubation. Depending on which high-frequency ventilator is used, positioning and turning infants on HFV may require two persons, one to rotate the infant while another caregiver briefly disconnects the ventilator circuit while the ventilator itself remains in a fixed location. The infant should be positioned to maintain the head in alignment with the body rather than turned to the side. This prevents obstruction of the flow of gases and disruption in ventilation.

Inhaled Nitric Oxide

The use of inhaled nitric oxide (iNO) is now commonplace for newborns receiving assisted ventilation. Originally approved for the treatment of pulmonary hypertension, iNO is now also used to treat premature infants with BPD. Care of the newborn receiving iNO includes careful monitoring of the gas administration and preventing any interruption of iNO administration during hand ventilation, turning, moving, or suctioning; CS systems are recommended. Monitoring of methemoglobin levels, suggested in studies of full-term infants treated with iNO for pulmonary hypertension (especially those on higher concentrations), was not found to be necessary in premature infants treated with iNO for BPD. However, a National Institutes of Health Consensus Statement found no advantage to the use of iNO in infants of <34 weeks’ gestation. Gradual weaning from iNO is necessary even in patients who are “nonresponders” because of the downregulation of the patient’s endogenous nitric oxide production during treatment with iNO and the potential for destabilizing patients with marginal oxygenation and reserves.

Sudden Deterioration

A sudden deterioration can occur as a result of a multitude of factors in the ventilated neonatal patient. The cause of acute deterioration is not always apparent and two clinicians are often necessary at the bedside. After the baby is disconnected from the mechanical device, hand ventilation with a resuscitation bag connected to a manometer is initiated immediately. The FiO ₂ is increased until oxygen saturation reaches the infant’s target range. Breath sounds are immediately auscultated; if equal bilaterally, the tube is likely to be in proper position and free from obstruction. If the breath sounds are distant, or if air entry is detected in the gastric areas accompanied by distension, or an audible cry is heard, the ETT may have slipped into the esophagus. An end-tidal CO ₂ monitor or detection device will show an absence of CO ₂ during expiration. The ETT should be immediately removed and bag and mask ventilation provided until it is determined whether reintubation is necessary. If replaced, the ETT should be securely taped at the same level as the previous tube, and an X-ray obtained to confirm appropriate ETT position.

If the breath sounds are louder on the right side, the ETT may have slipped into the right main tem bronchus. A chest X-ray can confirm this diagnosis or perhaps identify an air leak in the left lung. If the ETT extends into the right bronchus, the left lung or the upper lobe of the right lung may appear to have atelectasis on X-ray. The appropriate adjustment to the ETT position is determined by measuring the tube position from the X-ray and then repositioning and taping the ETT securely.

If the ETT is plugged with secretions, breath sounds may be diminished bilaterally, with decreased rise of the chest wall during hand ventilation. Initially, the ETT is suctioned to attempt to remove the secretions. If this measure is unsuccessful, the ETT is removed and bag and mask ventilation initiated until the ETT is replaced.

A large pneumothorax typically presents with cyanosis, bradycardia, decreased blood pressure, narrowing pulse pressure, and diminution of the QRS complex on the ECG. The point of maximal impulse of the heart may be shifted away from the side with the air leak, and breath sounds may be diminished or absent on the affected side. The diagnosis of a pneumothorax can be confirmed with transillumination of the chest with a high-density fiber-optic light source or with a chest X-ray. When the infant is significantly compromised it may be necessary to decompress the chest with needle aspiration before the diagnosis is confirmed radiographically. Once the air is evacuated and the patient stabilized, a chest tube is inserted and attached to a drainage system to assist in air removal.