Gastro-oesophageal reflux in children: comparison of different durations, positions and sleep-awake periods of pH monitoring in the same patient

The Role of Sleep in the Modulation of Gastroesophageal Reflux and Symptoms in NICU Neonates

BACKGROUND

Newborns sleep about 80% of the time. Gastroesophageal reflux disease is prevalent in about 10% of neonatal intensive care unit infants. Concurrent polysomnography and pH-impedance studies clarify the relationship of gastroesophageal reflux with sleep.

AIMS

To characterize spatiotemporal and chemical characteristics of impedance-positive gastroesophageal reflux and define symptom associations in sleep and wake states in symptomatic neonates. We hypothesized that frequency of impedance-positive gastroesophageal reflux events and their association with cardiorespiratory symptoms is greater during sleep.

METHODS

Eighteen neonates underwent concurrent polysomnography with a pH-impedance study. Impedance-positive gastroesophageal reflux events (weakly acidic or acidic) were categorized between sleep versus wake states: Symptom Index = number of symptoms with gastroesophageal reflux/total symptoms*100; Symptom Sensitivity Index = number of gastroesophageal reflux with symptoms/total gastroesophageal reflux*100; Symptom Association Probability = [(1 - probability of observed association between reflux and symptoms)*100]).

RESULTS

We analyzed 317 gastroesophageal reflux events during 116 hours of polysomnography. During wake versus sleep, respectively, the median (interquartile range) frequency of impedance-positive gastroesophageal reflux was 4.9 (3.1-5.8) versus 1.4 (0.7-1.7) events/hour (P < 0.001) and the proximal migration was 2.6 (0.8-3.3) versus 0.2 (0.0-0.9) events/hour (P < 0.001). The Symptom Index for cardiorespiratory symptoms for impedance-positive events was 22.5 (0-55.3) versus 6.1 (0-13), P = 0.04, whereas the Symptom Sensitivity Index was 9.1 (0-23.1) versus 18.4 (0-50), P = 0.04, although Symptom Association Probability was similar (P = 0.68).

CONCLUSIONS

Contrary to our hypothesis, frequency of gastroesophageal reflux in sleep is lower; however, spatiotemporal and chemical characteristics of gastroesophageal reflux and symptom-generation mechanisms are distinct. For cardiorespiratory symptoms during sleep, a lower Symptom Index entails evaluation for etiologies other than gastroesophageal reflux disease, a higher Symptom Sensitivity Index implies heightened esophageal sensitivity, and similar Symptom Association Probability indicates other mechanistic possibilities.

Relationship between gastro-oesophageal reflux and gastric activity in newborns assessed by combined intraluminal impedance, pH metry and epigastric impedance

The pathogenesis of gastro-oesophageal reflux disease (GORD) is complex and multifactorial. A motility disorder resulting from immaturity of the gastro-oesophageal tract may be involved. We have combined multichannel intraluminal impedance (MII) and pH monitoring with epigastric impedance (EGI) to evaluate the activity of this tract in neonates with suspected GORD. Multichannel intraluminal impedance, pH and EGI were followed for 3 h in 30 newborns displaying apparent life-threatening events and signs of GORD. Simultaneous application of MII and pH monitoring identifies reflux episodes and illustrates their duration, height and pH. Episodes detected by MII were placed on the EGI curve and the contemporaneous gastric filling state and emptying velocity were calculated. During the total measuring time, 248 reflux episodes were revealed. An inverse correlation was evident for reflux frequency and gastric emptying velocity (r2 = 0.94; P < 0.001), and between acid refluxes and the gastric filling state (r2 = 0.95; P < 0.001), whereas a positive correlation was found between the reflux level and the gastric filling state (r2 = 0.52; P < 0.05). Simultaneous MII, pH and EGI monitoring provided new information on the relationship between refluxes and gastric activity. Data suggest that gastric emptying patterns influence the frequency, level and pH of reflux episodes.

The role of gastro-oesophageal reflux in the aetiology of SIDS

Gastro-oesophageal reflux (GOR) has been identified as a possible cause of SIDS. Several features of GOR unique to infants presenting with apparent life-threatening events (ALTEs) have led to its 'pathogenic' definition. One is that the life-threatening apnoea itself is initiated by GOR, another is that the ALTE relates to prolonged reflux during sleep, in a vulnerable sleep-state, and finally that the ALTE relates to excessive quantities of GOR. The presumption of GOR 'pathology' as a cause of SIDS however, is questionable in these susceptible infants for three reasons: firstly, GOR is physiological and occurs in most infants; secondly, there is no general consensus on what constitutes normal physiological reflux, and thirdly, variation in the recording technique and methods of data analysis and interpretation may account for the differences between study groups. It seems likely therefore if GOR is implicated in SIDS, additional factors are involved. Under certain circumstances, physiological GOR may trigger life-threatening apnoea in apparently healthy infants, that leads to SIDS. One mechanism that could explain such a death is reflex apnoea by stimulation of laryngeal chemoreceptors (LCR) during sleep. The conditions under which this could be fatal are the occurrence of gastric contents refluxed to the level of the pharynx during sleep, in the young infant who has depressed swallowing and arousal. That is, the occurrence of GOR to the level of the pharynx during sleep, an infrequent event that is usually innocuous, could be converted to a fatal event if swallowing is impaired and arousal depressed, by a variety of mediating factors such as prone sleeping, prematurity, sedatives, seizures or upper respiratory tract infections. The identification of LCR responses, particularly in prone sleeping and premature infants provide further evidence that this mechanism may be implicated in the aetiology of SIDS in apparently healthy infants.

Gastroesophageal reflux and respiratory phenomena in infants: status of the intraluminal impedance technique

BACKGROUND

The coincidence of recurrent respiratory symptoms and gastroesophageal reflux (GER) is a well-known phenomenon in infants. Twenty-four-hour pH metry is the presumed gold standard of diagnostic tools for this symptom complex, but with this method, only acid (pH <4) and alkaline (pH >7) GER can be detected. Gastroesophageal reflux with an esophageal pH in the physiological range (pH 5-6.8) may represent many cases of clinically relevant GER unrecognized by pH metry. In this study the intraluminal multiple electrical impedance (IMP) procedure for complete registration of GER was compared with pH metry for its diagnostic value in the presence of respiratory symptoms.

METHODS

Twenty-two infants with recurrent regurgitation or pulmonary problems were investigated simultaneously with IMP, pH metry, and polygraphy during two feeding periods. Heart rate, oxygen saturation, sleep states, and oronasal flow were recorded, among other parameters.

RESULTS

Three hundred sixty-four occurrences of GER were detected by IMP; only 11.4% had a pH less than 4 and were therefore recognized by pH metry. Three hundred twelve (84.8%) occurrences were associated with breathing abnormalities, and 11.9% of these were detected by pH metry. Nineteen instances were accompanied by a decrease of oxygen saturation of more than 10% of the initial value. Only three (15.8%) of these had a pH less than 4. The remaining 16 reflux episodes were recognized by IMP only. After software-aided preselection, 165 instances of apnea were visually validated, 49 of which were accompanied by GER. Thirty-eight (77.6%) of these were exclusively recorded by IMP.

CONCLUSIONS

The use of pH metry alone cannot detect most GER incidents accompanied by respiratory symptoms and therefore does not appear to be suitable for this approach. The pH-independent IMP technique promises to be a reliable tool for presumably GER-associated respiratory symptoms.

Posture and gastro-oesophageal reflux: a case for left lateral positioning

AIM

Prone posture is often recommended for symptomatic gastroesophageal reflux in young infants, but prone positioning has been associated with sudden infant death. The aim of this study was thus to establish the optimal alternative posture for reducing reflux.

METHODS

24 infants (< 5 months) with symptomatic gastro-oesophageal reflux were studied prospectively with 48 h pH monitoring. They were randomly assigned to one of the 24 permutations of the four positions (supine, prone, right, left). During the first 24 hours the infant was held horizontally, and then the permutation was repeated at 30 degrees head elevation, giving a total of eight study segments for each infant. Data were edited to remove all time when the infants were not in the prescribed positions. Results were evaluated using analysis of covariance.

RESULTS

Gastro-oesophageal reflux expressed as reflux index (mean % (SEM)) was significantly less in the prone and left lateral positions (6.72 (1.06) and 7.69 (1.03) respectively) than in the supine and right lateral positions (15.33 (2.33) and 12.02 (1.38); p < 0.001). Head elevation did not affect any variables significantly.

CONCLUSIONS

Head elevation may not always be of clinical value. The left lateral position is a suitable alternative to prone for the postural management of infants with symptomatic gastro-oesophageal reflux.