Pediatric Equipment

Richard H. Blum , Charles J. Coté , in A Practice of Anesthesia for Infants and Children (Fourth Edition), 2009

Apnea Monitors

Apnea monitors, whether based on transthoracic impedance, motion, or other patient parameters, are helpful in the perioperative and recovery room phases for former preterm infants less than 60 weeks' postconceptual age. 386 Infants with a history of apnea spells and children with ongoing apnea spells are much more likely to develop apnea in the postoperative period. Even if an infant has had a period of some months with a normal respiratory pattern at home, the anesthetic state may bring about a temporary return of apnea spells, and such a monitor should be used according to current guidelines (see Chapters 2, 4, 35, and 36).

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Perinatology

Vinnie DeFrancesco , in Clinical Engineering Handbook, 2004

Apnea Monitors

Apnea monitors are part of the patient monitoring systems in the PICU and NICU ( Neuman, 1988a). Some stand-alone apnea-monitoring systems are frequently used in the home for infants who have had apneic episodes in the hospital or who are at risk of apnea. (See Figure 93-7.) These incorporate heart rate monitoring as well as respiratory monitoring. Monitoring of breaths is typically done by transthoracic impedance monitoring. The same electrodes that are used to detect the ECG for heart rate monitoring are used to conduct a low-level, high-frequency (20-100 kHz) current through the infant. Breathing motions change the impedance, thus resulting in a voltage change detected by the monitor. When the monitor senses that breathing motions have ceased, it alarms after a delay of typically 20 seconds. The alarm alerts the care-giver to intervene. In many cases, an apneic infant will resume breathing in response to slight tactile stimulation. In some cases, aggressive cardiopulmonary resuscitation is required.

Figure 93-7. Transthoracic impedance apnea and heart-rate monitor.

Apnea monitoring is an imperfect technology in that all techniques that are used to detect breathing (e.g., transthoracic impedance, pressure sensors, airway temperature monitoring, pneumotachography, carbon dioxide sensors, and sound detectors) are susceptible to artifact, which can defeat the alarm system of the monitor. Dyro (1976, 1978) has described the hazards and risks of a wide range of apnea monitoring technologies. Environmental factors such as external vibrations from other devices and electromagnetic interference, and internal factors such as cardiogenic artifacts can cause the monitor to detect breaths when the infant is not breathing (Dyro, 1998).

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Sudden Infant Death Syndrome and Apparent Life-Threatening Events

Andrea Coverstone MD , James Kemp MD , in Kendig's Disorders of the Respiratory Tract in Children (Ninth Edition), 2019

Monitoring Premature Infants at Home

Studies evaluating compliance with apnea monitor use suggest high rates of compliance among infants with AOP, particularly during the first month at home. 87 Abuses because of self-interest among those prescribing monitors notwithstanding, 32,88 the promise or potential of monitors, when used to prevent deaths among "nursery graduates," should not be discounted. Infants born at 24–36 weeks PMA are 2.1–3.3 times as likely to die of SIDS as infants born at greater than 37 weeks. 89

The issue of monitor use is quite complex, however. In their review of more than 37,000 deaths and 3.8 million linked births, Malloy and Hoffman showed that, depending on the estimated gestational age, the age of SIDS deaths among premature infants was, on average, 44.2 weeks to 47.8 weeks PMA (range, 32–85 weeks). 89 On the basis of these data and those of the CHIME study, 29 wherein "extreme" apneic spells among premature infants "disappeared once the infants were 43 weeks postconceptional age," one editorial writer declared that the usefulness of prescribing monitors to detect extreme apneic spells and to prevent sudden death among premature infants and the "physiological basis for such a practice are more in doubt than ever." 32 However, because infants who have died were certainly apneic at least once, another possible scenario is that the time course of dangerous apnea activity among those premature infants dying is different from those having apnea and not dying. The vexing problem remains whether it is possible to select candidates who will benefit most from monitoring. Monitoring for apnea in preterm infants must continue to be part of this discussion. Malloy has shown that the adjusted odds ratio for deaths called SIDS for infants born between 24 and 28 weeks was 2.57, even given the propensity for attributing their deaths to causes related to complications of prematurity. 90

For the time being, we are in agreement with the AAP recommendations for monitoring premature infants having apnea until they are 43 weeks PMA. 32,91 Because the average time course until cessation of apnea among those infants dying must be different from that for the premature infants in the CHIME study, monitoring infants past 43 weeks PMA who have frequent apnea lasting longer than 20 seconds, especially with reductions in heart rate, also seems prudent.

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A worldwide yearly survey of new data in adverse drug reactions

Rebecca Gale , Alison Hall , in Side Effects of Drugs Annual, 2015

Respiratory

A prospective study used a sleep apnoea monitor to detect oxygen desaturation events (defined as blood oxygen saturation drop below 94%) during sedation with propofol-remifentanil for dental extraction in 174 patients. There was an increase in desaturation events with increasing body mass index (81.8% vs. 20% in underweight patients). Odds of one desaturation event were 1.2 times higher for each BMI unit increase (OR 1.2, 95% CI 1.1–1.3). Males were 2.6 times as likely to desaturate than females for a given BMI (OR 2.6, 95% CI 1.2–5.25) [41c].

Case report

An 86-year-old on dabigatran for atrial fibrillation underwent percutaneous pinning of an impacted right femoral neck fracture at 28 hours post-injury. The dabigatran was a contraindication to neuroaxial anaesthesia and general anaesthesia was felt to be undesirable due to the patients' co-morbidities. The patient received 2   mg midazolam and 50 micrograms of fentanyl as a premed and then general anaesthesia was undertaken with this relates more to phenobarbitol side effects than propofol (145   mg), ketamine (25   mg) and lidocaine (50   mg) combined in a 20-mL syringe. Following the first 2-mL bolus of the mixture, the patient required a nasopharyngeal airway to maintain patency as the patient became obtunded to the point of snoring and supplementary ventilatory support was needed with a bag and mask for 5   minutes. Given the polypharmacy used in this technique, it is difficult to attribute the respiratory complication to one agent in particular [42A].

A study investigated cytokine release in the lung epithelial lining following one lung ventilation for oesophagectomy. This small prospective study randomly assigned 20 patients to receive either propofol or sevoflurane maintenance following an intravenous induction. Lung epithelial lining fluid was obtained by bronchoscopy before and after one lung ventilation with paired blood samples. The pro-inflammatory cytokine, IL-6 was significantly increased in both lungs following one-lung ventilation in the sevoflurane group but there were no changes in the propofol group. The pro-inflammatory chemokine, IL-8, was also increased in the sevoflurane group but only in the dependent, ventilated lung and there were no changes in the concentrations of IL-10 (anti-inflammatory) in either lung or group. Post-operatively, there were no differences in the clinical parameters of respiratory failure (P/F ratio) or in the duration of acute lung injury. This suggests that propofol may suppress the pro-inflammatory response to one lung ventilation and oesophagectomy; however, this study is too small to claim an effect of this on clinical outcome [43c]

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Confirmation of Endotracheal Intubation

M. Ramez Salem , Anis S. Baraka , in Benumof and Hagberg's Airway Management, 2013

p Impedance Respirometry

Impedance respirometry, which measures electrical conductivity of the thorax, has been used to monitor respiratory rate in the critical care setting and to monitor apnea in infants. The ability of impedance respirometry to distinguish esophageal from endotracheal intubation has been explored. 66,67 A high-frequency alternating current is passed between two electrodes placed on the anterior chest wall. With the increase in lung volume during inspiration, there is an associated decrease in lung electrical conductivity and therefore increased impedance. 66,67 These changes can be measured and displayed as a waveform. If the esophagus is intubated, such an effect on thoracic impedance should be absent. Although assessment by thoracic impedance plethysmography was found to have 100% sensitivity in the detection of esophageal ETT placement in a study in adult patients, 66 it correctly identified only 76 of 80 ETTs in children. 67 Of those incorrectly identified, one was in the trachea and three were in the esophagus. Obviously, more studies are needed before any conclusions can be made. Although it is not a perfect test, use of impedance respirometry could decrease the time taken to identify incorrect placement when combined with other methods of ETT verification. 67

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Circadian Rhythm Sleep Disorders (CRSD)

D. Sinha , in Encyclopedia of Sleep, 2013

Treatment

Although periodic breathing is very distressing for parents, it does not require treatment and parents should be reassured that this is a normal breathing pattern in infants which should resolve with age. Apnea monitors have been used; however, they often cause more distress for the parents, and are therefore not recommended.

Treatment of OSA varies. The first question arises as to when to treat. Studies have shown that apneas can occur in otherwise healthy children and tend to reduce in frequency and duration with age, and often resolve by the first year of life. The consequences of having mild OSA are also not fully understood. Thus, the decision to treat will be based on the infant's other medical concerns, presence of symptoms and/or complications such as failure to thrive, as well as physical exam findings.

Continuous positive airway pressure (CPAP) may be used at any age. With delivery of positive pressure, the airway opening is maintained and collapse prevented. It has been shown to be safe and effective in infants. It is a noninvasive method of treating apnea in infants, especially given that the events may resolve with age and the infant may then not require long-term treatment. In the United States, difficulty arises in the lack of availability of masks for this age group. In older children, adjustment to wearing CPAP is a major concern; however, this is less of an issue with infants. Side effects occasionally do occur, including nasal congestion, irritation of the skin from the mask, or bloating from air entering the alimentary tract. These can be reduced by using a heated humidifier, appropriate fitting mask or gel pad, and adjusting the pressure. CPAP can be expected to improve the Apnea Hypopnea Index (AHI) as well as sleep fragmentation and possible REM sleep.

For those with craniofacial abnormalities, surgical correction may be performed. For example, those with micrognathia or midface hypoplasia may have mandibular or maxillary deficiency, respectively. Distraction osteogenesis can be performed, in which osteotomy is followed by slow distraction of the mandible by an external device. For those with macroglossia, tongue reduction surgery may be performed. In those with obstruction localized to the soft palate, uvulopalatopharyngoplasty may be performed, in which the uvula, tonsils, and the posterior part of the soft palate are removed; however, this may be complicated by velopharyngeal insufficiency.

For older infants, tonsillectomy and adenoidectomy may be considered. Previously, success rates have been as high as 80% in children with OSA, although more recent studies show that figure to be closer to 50%. Many ear, nose, and throat surgeons do not routinely perform this procedure on infants; however, it may be indicated in those with severe OSA, or those with associated complications. Given that infants would be considered high-risk patients for this procedure, it should be performed in a setting where pediatric intensive care support is available and should be followed by overnight monitoring with pulse oximetry.

Tracheotomy was previously performed for those in whom other surgeries were not successful. It is rarely required these days as most infants tolerate CPAP.

Supplemental oxygen has been used in the past, with improved oxygenation; however, it may also result in increased carbon dioxide levels and therefore should be used with caution in children. It does not affect the number or duration of apneas, work of breathing, or arousals and so it is not generally indicated as a treatment, other than for temporary stabilization purposes.

Weight control for those with Prader–Willi, hypothyroidism, or obesity is helpful. While weight loss is not necessarily a goal in this age group, limited weight gain may help control the severity of OSA. Parents should do this in conjunction with their pediatrician to ensure adequate nutrition for growth is achieved in infants.

Body position has been studied in children. While adults tend to have more severe OSA in the supine position, children have been shown to have a lower apnea hypopnea index in the supine position compared to the prone position. One study investigating the position of infants who died unexpectedly in their crib showed that 89% of the infants had airway occlusion on CT scan when in the prone position, while only 18% had obstruction in the supine position. Furthermore, a large study looking at the sleeping position of children showed those with OSA spent more time in the supine position, suggesting that sleeping in the supine position may not be detrimental, as is so in adults. In infants, this also helps to reduce the risk of SIDS and is the recommended sleeping position for all infants.

One study retrospectively looked at the feeding methods of infants who presented with snoring and found that those who had been breastfed had lower AHI than those who were never breastfed. Breastfeeding up to 5 months appeared to be beneficial. Although these are preliminary results, it may be another reason to encourage breastfeeding.

Medications such as systemic steroids have been studied with no significant benefit. A small study evaluating inhaled steroids and montelukast in children has shown promise but needs further evaluation.

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A 1-month-old premature infant on an apnea monitor

Lourdes M. DelRosso , in Pediatric Sleep Pearls, 2017

Discussion

Apnea monitors record breathing effort by detecting the difference in impedance between two electrodes placed on the infant's chest and secured with a belt. These electrodes also detect the heart rate. The standard monitor settings for home apnea monitoring include apnea delay of 20 seconds (the monitor records the previous 20 seconds after the alarm is triggered), low heart rate at 80 beats/min, and high heart rate at 210 beats/min. The monitors do not have a delay on the bradycardia alarm. Shallow breaths, loose electrodes, and/or inadequate placement or tightening of the impedance belt can also trigger the alarm. Figure 34-1 demonstrates a prolonged central apnea with bradycardia. Note that the small pulsations seen during the apnea are due to an electrocardiogram (ECG) artifact. In contrast, Figure 34-2 shows a prolonged period of low-amplitude artifact that was incorrectly identified as an apnea by the monitor software. Note that the amplitude on the respiratory channel is at a different frequency than that of the ECG, and there is no associated change in heart rate.

The International Classification of Sleep Disorders, third edition (ICSD-3) defines apnea of prematurity as observed apnea or cyanosis, or a detected central apnea, bradycardia, or desaturation on hospital cardiorespiratory monitoring, in an infant of postconceptional age <37 weeks at the time of presentation. A nocturnal polysomnogram (if performed) must show evidence of prolonged central apneas (more than 20 seconds duration) or periodic breathing (see Case 12 A 7 month-old infant with a series of central apneas) for more than 5% of the total sleep time. In many cases, the infant also has obstructive apneas and mixed apneas. Other medical, neurologic, or sleep disorders, as well as medication effects, must be ruled out. When the same diagnostic criteria are found in an infant born at 37 weeks conceptional age or later, but the diagnosis is changed to "apnea of infancy." The younger the conceptional age at birth, the greater the prevalence of apnea of prematurity.

The etiology of apnea of prematurity has been attributed to immaturity of the central nervous system. The central control of breathing, located in the brainstem, regulates ventilatory responses to CO2. Studies have shown impaired hypercapnic responses in premature infants and increased ventilatory responses to CO2 as the infant grows older. The peripheral carotid body receptors respond to hypoxia, hypercarbia, and acidosis, having a significant effect on ventilation. The chest wall compliance of a premature infant results in lower end-expiratory lung volume and distal airway closure. Bradycardia may result from stimulation of carotid chemoreceptors by hypoxia. 1,2

Management of apnea of prematurity may include methylxanthine therapy, continuous positive airway pressure (if significant obstructive events are present), and home monitoring. Both theophylline and caffeine have been effective in increasing minute ventilation, improving CO2 sensitivity, and decreasing periodic breathing. Apnea of prematurity generally resolves by 43 weeks postconceptional age. 3 If apnea persists past that time, the patient should be evaluated for other causes (e.g., gastroesophageal reflux or unsuspected hypoxemia from chronic lung disease).

The American Academy of Pediatrics recommends the use of home cardiorespiratory monitors for premature infants who are noted to have significant apnea, bradycardia, and/or hypoxemia in the newborn nursery or on the floor before discharge. Apnea monitors should be used up to 43 weeks postconceptional age or after the cessation of the cardiorespiratory episodes, whichever is later. 4 Caregivers must be instructed regarding appropriate responses to the monitors.

Clinical Pearls

1.

Apnea of prematurity is likely secondary to immaturity in the central control of breathing.

2.

Management of apnea of prematurity may include methylxanthine therapy and home apnea monitoring.

3.

Apnea monitors should be used in symptomatic infants up to 43 weeks postconceptional age or after the cessation of the cardiorespiratory episodes, whichever is later.

4.

If apnea or bradycardia persists after 43 weeks, further investigation is warranted.

5.

Many events labeled as apneas by monitor software automatic scoring are, in fact, artifacts.

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Failure to Thrive

D.R. Fleisher , in Encyclopedia of Infant and Early Childhood Development, 2008

Case Vignette: Type III Failure to Thrive – Factitious Disorder by Proxy (Also Known as Munchausen Syndrome by Proxy)

A 5-week-old girl born near term weighing 7 lb was said to have vomited her initial feedings and was switched to a soy-based formula. Alleged apnea spells in the newborn nursery prompted her discharge with an apnea monitor at 2  days of age. She was re-hospitalized at 4   days of age for unverified apnea and discharged 2 days later on a hypo-allergenic formula. It was reported that vomiting occurred about 12   times a day and was often projectile. At 5 weeks, she had gained only 7 oz above her birth weight and she had a severe diaper rash.

At 8 weeks, she weighed only 1 oz more, her rash was more severe, and she was scrawny, irritable, and ravenously hungry. She was then hospitalized for 29   days. The patient consumed large amounts of formula with a calculated daily caloric intake that was twice that expected of a well baby. Nevertheless, she failed to gain. On the 11th day, it was noticed that her urines were invariably dilute. A sample of leftover formula and a sample of formula from an unopened bottle were taken from her room for chemical analysis. The sodium concentration in the small amount of leftover formula was found to be about half that of the formula from the unopened bottle. Despite the mother's assurances to the contrary, the formula had been diluted. The patient occupied a private room and was cared for exclusively by the mother and maternal grandmother. They always declined help from the nursing staff. Observations of feeding revealed that the mother related to her 10-week-old infant as though the baby were able to obey or disobey and respond to disciplinary measures. The mother and maternal grandmother fed the infant in an adversarial, teasing manner. In an individual interview with the father, he described his wife's medical history in terms that were typical of ongoing factitious disorder since childhood. On the 14th hospital day, the infant's malnutrition seemed life-threatening. She was transferred to the pediatric intensive care unit (ICU). The next morning, the attending, resident physicians and social worker held a conference with the family about the possibility that the patient's failure to gain weight might be caused by consumption of diluted or tainted formula. In order to test this possibility, we requested a 5-day trial during which the patient would remain in the ICU and be handled and fed only by the nursing staff. There was to be absolute physical separation of all friends and family members from the infant. They were told that, painful as the prospect of separation was, it was the only way we could explore the possibility that someone was doing something that was making their baby waste away. The parents reluctantly agreed to not approach the baby closer than 10 ft and a red line was taped to the floor encircling the crib which was placed directly in front of the nurses desk. The patient promptly gained weight. The diagnosis of Munchausen syndrome by proxy was confirmed and the baby was placed into high-quality foster care. When the foster-mother brought her for a follow-up visit 3.5   weeks after discharge, the patient was alert, no longer irritable, and had continued the catch-up pattern of weight gain that began in the pediatric intensive care unit ( Figure 7 ).

Figure 7. Type III FTT. An infant with Munchausen syndrome by proxy. The longer horizontal bar indicates the total period of hospitalization. The shorter bar indicates the part of her hospital stay during which she was closely observed in the intensive care unit, separated from her mother and maternal grandmother.

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Pediatric Sleep-Wake Disorders

Suresh Kotagal , in Review of Sleep Medicine (Second Edition), 2007

Outcome and Management

The recurrence rate for severe ALTEs may be as high as 60%, with the second event generally occurring within a few days of the initial event. There is an active and unresolved debate about whether infants should be sent home on apnea–heart rate monitors. Opponents of apnea monitors state that they do not prevent SIDS—patients have died while still wearing these devices—and that they are not cost effective. 51 Proponents may counter that an estimated 13% of ALTE subjects can go on to develop SIDS 52 ; thus monitoring is vital. The bias of this author is toward monitoring for 2 to 3 months after the initial event. Monitoring should be discontinued by the age of 6 months, which is well past the age of occurrence of SIDS. Parents should be familiar with cardiopulmonary resuscitation and may also need refresher courses.

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Managing and Monitoring Anaesthesia

Paul Flecknell , in Laboratory Animal Anaesthesia (Fourth Edition), 2016

Anaesthetic Breathing System Disconnection

The risk of inadvertent disconnection of the animal, the anaesthetic breathing system and the anaesthetic machine can be reduced by using safe-lock type connectors. The most frequent point of disconnection is at the junction of the breathing system and the endotracheal tube. It is possible to position a thermistor-type apnoea alarm in the breathing system and this can provide an alert if disconnection occurs. When anaesthetizing larger animals, pressure monitoring can be used in the breathing system that will detect both low pressure due to disconnection and high pressure caused, for example by a malfunctioning expiratory valve. An oxygen analyser, positioned within the fresh gas flow of the breathing system, will detect disconnection of the breathing system from the anaesthetic machine and also any failure of the oxygen supply. Some machines are fitted with an audible alarm that is activated if the oxygen pressure falls below a lower limit.

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