Lung mechanics and breathing pattern during wakefulness and sleep in children with enlarged tonsils

Effects of upper airway obstruction or hypoxia on gastroesophageal reflux in newborn lambs

BACKGROUND

Although it is commonly accepted that upper airway obstruction (UAO) increases gastroesophageal reflux (GER), the link is poorly understood and insufficiently documented. In addition, while hypoxia is often encountered in infants with UAO, its consequences on GER are virtually unknown. The two aims of the present study were to characterize the effects of (1) UAO and (2) hypoxia on GER.

METHODS

Seventeen lambs underwent polysomnographic and esophageal impedance/pH-metry monitoring during UAO vs. a control condition (6 h, ten lambs) or 10% hypoxia vs. normoxic condition (3 h, seven other lambs).

RESULTS

Moderate-to-severe UAO was maintained throughout monitoring (inspiratory tracheal pressure of -13 (-15, -12) cm H₂O vs. -1 (-1, -1) cm H₂O in control condition, p = 0.005). While the number of GERs increased with UAO (2 (1, 4) vs. 0 (0, 3) in the control condition, p = 0.03), the increase was less than anticipated and inconsistent among the lambs. Also, sustained 10% hypoxia did not alter the number of GERs (2 (1, 3) vs. 0 (0, 5) in the control condition, p = 0.9).

CONCLUSIONS

The presence of an UAO for 6 h mildly increased the number of GERs, whereas hypoxia for 3 h had no significant effect.

IMPACT

The effect of upper airway obstruction and hypoxia on gastroesophageal reflux is poorly documented in the neonatal period. A moderate-to-severe upper airway obstruction for 6 h results in a mild, inconsistent increase in the number of gastroesophageal refluxes. Overall, a hypoxia of 10% for 3 h had no significant impact on gastroesophageal reflux. The prescription of an antireflux medication in infants with upper airway obstruction must not be systematic but rely on objective signs of a pathologic gastroesophageal reflux.

Use of nasal cannula for detecting sleep apneas and hypopneas in infants and children

We evaluated tolerance of nasal cannula (NC) by 14 infants (median age, 2.6 months) and 16 children (median age, 5.5 years) with suspected obstructive sleep apnea syndrome and compared the efficacy of the NC with that of a nasobuccal thermistor in detecting obstructive apneas (OA) and obstructive hypopneas (OH) on polysomnography traces. The relationship between cannula flow and esophageal pressure was assessed in six patients. Time spent with an uninterpretable flow signal was longer when using a cannula than when using a thermistor in infants (p < 0.05) and children (p < 0.01), and it was longer in the younger patients (p < 0.05). Among the 650 OA-OH detected by either method, only 38% were detected by both, and 58% were detected by the cannula and missed by the thermistor, so that the apnea-hypopnea index was higher with cannula than with thermistor in each age group (p < 0.01). More hypopneas than apneas were detected by the cannula and missed by the thermistor (p < 0.001). Out-of-phase thoracic and abdominal motions and/or changes in the end-tidal CO(2) signal shape were associated with 86% of OH identified by cannula. In the six patients whose esophageal pressure was measured, all respiratory events identified using a cannula were associated with increased "airway resistance." Thus, the NC is more likely than the thermistor to detect OA and OH in infants and children, and this superiority is particularly marked for hypopneas.

Sleep-related breathing disorders. 6. Obstructive sleep apnoea syndrome in infants and children: established facts and unsettled issues

The presence of increased upper airway resistive loads during sleep can now be diagnosed by paediatricians. However, diagnostic criteria need to be further clarified to allow accurate identification of episodes of partial airway obstruction. New technological advances can be expected to help to determine the clinical usefulness of ambulatory testing during sleep and thus to establish the indications for polysomnographic investigations in the laboratory. A thorough investigation of the anatomical abnormalities that contribute to airways obstruction is essential for selecting the most appropriate therapy. However, the order in which these investigations should be performed remains unclear. The diagnostic tools, including questionnaires and sleep testing, and methods aimed at investigating pathophysiological mechanisms should be standardised for multicentre studies. Familial factors should be taken into account. The best strategy for preventing the complications of the OSA syndrome is to identify the disorder as early as possible. This requires close cooperation between adult physicians and paediatricians called upon to evaluate sleep-related disorders.

Asynchronous chest wall movements during non-rapid eye movement and rapid eye movement sleep in children with bronchopulmonary dysplasia

The aim of this study was to assess whether age-related changes in thoracic shape modify patterns of thoracoabdominal asynchrony (TAA) or applicability of phase angle analysis during sleep in young children with increased respiratory loads. We assessed TAA during polysomnographic monitoring in 14 young children (mean age 32 months, range 19 to 46; mean weight 12.5 kg, range 9.3 to 17) with severe bronchopulmonary dysplasia (BPD). Of the patients 10 were severely enough affected to require tracheostomy. We measured asynchrony of rib cage (RC) and abdominal (AB) movements at midinspiration and the corresponding phase angle from oscillographic recordings during both non-REM and REM sleep. We measured the amplitude of "paradoxical" displacement of either RC or AB during inspiration and expressed this as a percentage of the total displacement of the compartment. Of 9 children who manifested early inspiratory AB paradox during non-REM sleep, 7 showed a figure eight on the Konno-Mead diagram. The magnitude of abdominal paradox during non-REM sleep was significantly positively correlated with age (n = 14, r = 0.68; p < 0.01). Phase angle was significantly negatively correlated with dynamic lung compliance (n = 14, r = -0.66; p < 0.01). During REM sleep, expiratory abdominal muscle activity was abolished and all patients with abdominal paradox "converted" to an open loop with RC paradox during inspiration. Graphic assessment of the Lissajous figure on the Konno-Mead diagram indicated when midinspiratory phase angle analysis did not reflect the severity of TAA and can be used to infer patterns of respiratory muscle recruitment. We conclude that young children manifest patterns of TAA that differ from the early inspiratory RC paradox commonly observed in infants. Comparison of RC-AB loops between non-REM and REM sleep in the same child can assess increased thoracic inspiratory efforts and expiratory muscle activity as potential mechanisms for abdominal paradox, as distinct from diaphragm ineffectiveness.

Respiratory disturbance during sleep due to adenoid-tonsillar hypertrophy

The pathophysiologic results of respiratory disturbances caused by adenoid-tonsillar hypertrophy are reported. In each case, we monitored intraesophageal pressure to accurately assess respiratory effort, and recorded a sleep diary to detect disorganized sleep habits and disturbed sleeping-waking rhythms. We noticed that great respiratory effort existed not only during light sleep, but was also continuously observed during deep sleep despite the total disappearance of obstructive apneas. Furthermore, upper airway obstruction caused by adenoid-tonsillar hypertrophy and hypoxemia during sleep in the rapid eye movement stage were found to be closely related to the sudden infant death syndrome. A sleep diary recording sleep habits and regularity of night sleep seems to provide reliable indicators for the determination of surgical intervention.