Kinesthetic stimulation for preventing apnea in preterm infants

Sensory stimulation for apnoea mitigation in preterm infants

Apnoea, a pause in respiration, is ubiquitous in preterm infants and are often associated with physiological instability, which may lead to longer-term adverse neurodevelopmental consequences. Despite current therapies aimed at reducing the apnoea burden, preterm infants continue to exhibit apnoeic events throughout their hospital admission. Bedside staff are frequently required to manually intervene with different forms of stimuli, with the aim of re-establishing respiratory cadence and minimizing the physiological impact of each apnoeic event. Such a reactive approach makes apnoea and its associated adverse consequences inevitable and places a heavy reliance on human intervention. Different approaches to improving apnoea management in preterm infants have been investigated, including the use of various sensory stimuli. Despite studies reporting sensory stimuli of various forms to have potential in reducing apnoea frequency, non-invasive intermittent positive pressure ventilation is the only automated stimulus currently used in the clinical setting for infants with persistent apnoeic events. We find that the development of automated closed-looped sensory stimulation systems for apnoea mitigation in preterm infants receiving non-invasive respiratory support is warranted, including the possibility of stimulation being applied preventatively, and in a multi-modal form. IMPACT: This review examines the effects of various forms of sensory stimulation on apnoea mitigation in preterm infants, namely localized tactile, generalized kinesthetic, airway pressure, auditory, and olfactory stimulations. Amongst the 31 studies reviewed, each form of sensory stimulation showed some positive effects, although the findings were not definitive and comparative studies were lacking. We find that the development of automated closed-loop sensory stimulation systems for apnoea mitigation is warranted, including the possibility of stimulation being applied preventatively, and in a multi-modal form.

Treating Apnea of Prematurity

Premature babies often suffer apnea of prematurity as a physiological consequence of an immature respiratory system. Hypercapnia may develop, and neonates with apnea of prematurity are at an increased risk of morbidity and mortality. The long-term effects of apnea of prematurity or their treatments are less clear. While a number of treatment options exist for apnea of prematurity, there is no clear-cut "first-line" approach or gold standard of care. Effective treatments, such as caffeine citrate, carbon dioxide inhalation, nasal continuous positive airway pressure, nasal intermittent positive pressure ventilation, and others, may be associated with safety concerns. More conservative treatments are available, such as kangaroo care, postural changes, and sensory stimulation, but they may not be effective. While apnea of prematurity resolves spontaneously as the respiratory system matures, it can complicate neonatal care and may have both short-term and long-term consequences. The role, if any, that apnea of prematurity may play in mortality of preterm neonates is not clear.

Apnea of prematurity: from cause to treatment

Apnea of prematurity (AOP) is a common problem affecting premature infants, likely secondary to a "physiologic" immaturity of respiratory control that may be exacerbated by neonatal disease. These include altered ventilatory responses to hypoxia, hypercapnia, and altered sleep states, while the roles of gastroesophageal reflux and anemia remain controversial. Standard clinical management of the obstructive subtype of AOP includes prone positioning and continuous positive or nasal intermittent positive pressure ventilation to prevent pharyngeal collapse and alveolar atelectasis, while methylxanthine therapy is a mainstay of treatment of central apnea by stimulating the central nervous system and respiratory muscle function. Other therapies, including kangaroo care, red blood cell transfusions, and CO(2) inhalation, require further study. The physiology and pathophysiology behind AOP are discussed, including the laryngeal chemoreflex and sensitivity to inhibitory neurotransmitters, as are the mechanisms by which different therapies may work and the potential long-term neurodevelopmental consequences of AOP and its treatment.

Stabilizing immature breathing patterns of preterm infants using stochastic mechanosensory stimulation

Breathing patterns in preterm infants consist of highly variable interbreath intervals (IBIs) that might originate from nonlinear properties of the respiratory oscillator and its input-output responses to peripheral and central signals. Here, we explore a property of nonlinear control, the potential for large improvement in the stability of breathing using low-level exogenous stochastic stimulation. Stimulation was administered to 10 preterm infants (postconceptional age: mean 33.3 wk, SD 1.7) using a mattress with embedded actuators that delivered small stochastic displacements (0.021 mm root mean square, 0.090 mm maximum, 30-60 Hz); this stimulus was subthreshold for causing arousal from sleep to wakefulness or other detectable changes in the behavioral state evaluated with polysomnography. We used a test-retest protocol with multiple 10-min intervals of stimulation, each paired with 10-min intervals of no stimulation. Stimulation induced an approximately 50% reduction (P = 0.003) in the variance of IBIs and an approximately 50% reduction (P = 0.002) in the incidence of IBIs > 5 s. The improved stability of eupneic breathing was associated with an approximately 65% reduction (P = 0.04) in the duration of O(2) desaturation. Our findings suggest that nonlinear properties of the immature respiratory control system can be harnessed using afferent stimuli to stabilize eupneic breathing, thereby potentially reducing the incidence of apnea and hypoxia.

Apnea in the newborn

Apnea, defined as cessation of breathing resulting in pathological changes in heart rate and oxygen saturation, is a common occurrence especially in preterm neonates. It is due to immaturity of the central nervous system (apnea of prematurity) or secondary to other causes such as metabolic disturbances etc. Secondary causes of apnea should be excluded before a diagnosis of apnea of prematurity is made. Methylxanthines and continuous positive airway pressure form the mainstay of treatment. Mechanical ventilation is reserved for apnea resistant to the above therapy. An approach to the management of apnea in neonates is described.

Kinesthetic stimulation for treating apnea in preterm infants

BACKGROUND

This section is under preparation and will be included in the next issue.

OBJECTIVES

Main question: in preterm infants with apnea, does the use of kinesthetic stimulation lead to clinically important reductions in clinical apnea and bradycardia (>50% reduction in number of episodes), use of mechanical ventilation (IPPV) or continuous positive airways pressure (CPAP), and neurodevelopmental disability, without clinically important side effects.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conferences, symposia proceedings, expert informants, and journal handsearching mainly in the English language.

SELECTION CRITERIA

All trials using random or quasi-random patient allocation in which kinesthetic stimulation in preterm infants was compared to placebo or no treatment for apnea of prematurity were included.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Collaboration and its Neonatal Review Group were used with separate evaluation of trial quality, data extraction by both authors and synthesis of data using relative risk and weighted mean difference. As all three trials were crossover trials, the data were extracted from all exposure periods and combined where appropriate. Measures of severity of apnea as well as the response to treatment were consistent with an evaluation of 'clinical apnea', as defined by the American Academy of Pediatrics (Nelson 1978).

MAIN RESULTS

Three crossover studies (Korner 1978, Tuck 1982 and Jirapaet 1993) were identified that compared a form of kinesthetic stimulation to control for the treatment of apnea of prematurity. Clinically significant apnea: None of the three studies showed an important reduction (>50%) in clinical apnea. Using a lower threshold (>25%), the study by Korner 1978 found less apnea and bradycardia in infants receiving kinesthetic stimulation. Tuck 1982 demonstrated reductions in the frequencies of apneas (> 12 seconds) associated with bradycardia (< 100 bpm), apneas associated with hypoxia (TcP02 < 50 mmHg), and apneas requiring stimulation in infants on the rocking bed. Individual patient data were not available from the author to determine if there was an important reduction in clinical apnea. No outcome could be extracted from the study by Jirapaet 1993 that was consistent with the definition of clinically important apnea. Other events: No significant differences were found in the incidence of infants requiring resuscitation, IPPV, CPAP or respiratory stimulants whilst receiving treatment. Adverse events such as death, intraventricular hemorrhage and neurodevelopmental follow up were not reported.

REVIEWER'S CONCLUSIONS

There is insufficient evidence to recommend kinesthetic stimulation as treatment for clinically significant apnea of prematurity. Previous reviews have suggested that kinesthetic stimulation is not effective at preventing apnea of prematurity (Henderson-Smart and Osborn 1998) and is not as effective as theophylline at treating clinically significant apnea of prematurity (Osborn and Henderson-Smart 1998).

Kinesthetic stimulation versus theophylline for apnea in preterm infants

BACKGROUND

Apnea of prematurity may lead to hypoxemia and bradycardia requiring resuscitative measures being instituted. Many treatments have been used in infants with apnea of prematurity, such as theophylline. Kinesthetic stimulation, which uses various forms of oscillating mattress, might also prevent apnea without using a standard drug such as theophylline.

OBJECTIVES

Main question: in preterm infants, how does kinesthetic stimulation compare with methylxanthine therapy in the treatment of apnea of prematurity.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants and journal handsearching mainly in the English language.

SELECTION CRITERIA

All trials using random or quasi-random patient allocation, in which kinesthetic stimulation was compared to methylxanthine therapy for apnea of prematurity, were eligible. No trials were excluded from the review that met these criteria.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Collaboration and its Neonatal Review Group were used with separate evaluation of trial quality, data extraction by both authors and synthesis of data using relative risk and weighted mean difference.

MAIN RESULTS

A single small study of 20 infants (Saigal 1986) demonstrated a significant benefit to the infants receiving theophylline compared to those on an oscillating water bed in terms of mean rates of clinically important apnea (apnea > 14 seconds and bradycardia < 100, and cyanosis or receiving stimulation). There were no significant differences in adverse effects (death, sleep states, the Albert Einstein Neurobehavioural Index, adverse neurological outcomes, and the Bayley Mental Development Index at six and 12 months), although the infants on the OWB had a higher psychomotor index at six but not 12 months. There were some differences between the groups in incidence and severity of respiratory distress syndrome, and baseline apnea rates.

REVIEWER'S CONCLUSIONS

The results of this review should be treated with caution. Theophylline has been shown in one small study to be superior to kinesthetic stimulation at treating clinically important apnea of prematurity. There are currently no clear research questions regarding the comparison of methylxanthines and kinesthetic stimulation to treat apnea of prematurity.

Kinesthetic stimulation for preventing apnea in preterm infants

BACKGROUND

Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia, which may be severe enough to require resuscitation including use of positive pressure ventilation or other treatments. Physical stimulation is often used to restart breathing and it is possible that repeated stimulation, such as with an oscillating mattress (kinesthetic stimulation), might prevent apnea and its consequences.

OBJECTIVES

In preterm infants at risk for apnea, does prophylactic use of kinesthetic stimulation lead to a clinically important reduction in apnea and bradycardia, and use of intemittent positive preswsure ventilation (IPPV).

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants, journal handsearching mainly in the English language.

SELECTION CRITERIA

All trials in preterm infants at risk of developing clinical apnea which utilised random or quasi-random allocation to treatment with an oscillating mattress or control, were eligible.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Collaboration and its Neonatal Review Group were used with separate evaluation of trial quality and data extraction by each author and synthesis of the data using relative risk.

MAIN RESULTS

There were no differences in short term effects (apnea /bradycardia, IVH, use of IPPV, sleep/wake cycles and neurological status at discharge) or longterm effects (in one trial - growth and development to one year).

REVIEWER'S CONCLUSIONS

Implications for practice. Prophylactic use of kinesthetic stimulation cannot be recommended to reduce apnea/bradycardia in preterm infants. Implications for research. There are currently no clear research questions regarding prophylactic use of kinesthetic stimulation to prevent apnea in preterm infants.