Background and aims: The relationship between apnoea of prematurity (AOP) and gastro-oesophageal reflux (GOR) has been frequently hypothesized. Both GOR and AOP occur frequently in preterm infants: actually, in clinical practice it is common to observe an increased frequency of AOP during postprandial periods, when the majority of GOR episodes also occurs. The widespread clinical perception that postprandial apnoeas in preterm infants can be related to GOR probably contributes to the well-known GOR over-treatment in this population. In a previous study, we found a significant increase of the frequency of AOP in the period following the onset of GOR, suggesting a possible causal relationship between GOR and AOP in a limited and variable proportion of AOP. We aim to evaluate whether physical and/or chemical features of gastro-oesophageal reflux (GOR) influence the relationship between GOR and apnoea of prematurity (AOP). Materials and methods: Fifty-eight preterm newborns (20 male) with gestational age ≤ 33 weeks were studied as they had recurrent apnoeas. None of them had malformation or major gastrointestinal problems, nor was taking drugs influencing gastrointestinal motility or gastric acidity. Each infant underwent a simultaneous recording of polysomnography (PSG) and combined impedance and pH monitoring (pH-MII). The investigator who analyzed pH-MII layouts was blind to the results of PSG, and vice versa. All the data, recorded during each postprandial period, were then separately analyzed. We analyze whether the correlation between GOR and AOP varies according to the acidity, duration and height of GOR episodes. All the episodes detected by MII with a concomitant decrease in pH to less than 4 are defined as acid MII-GOR (a-MII-GOR), while the episodes with a pH >4 are defined as non-acid MII-GOR (Na-MII-GOR). Acid GOR episodes recorded only by pH probe are defined a pH-GOR. PSG detects apneas by recording of breathing movement, nasal airflow, electrocardiogram and oxygen saturation. We considered as apnoeas each oral/nasal flow cessation lasting at least 5 seconds. Apnoeas were then classified as central (CA), obstructive (OA) and mixed (MA) depending on absence or presence of obstructed respiratory efforts. Apnoeas detected in the 1-minute time around the onset of each kind of GOR were further divided into apnoeas detected 30” before and 30” after the onset of GOR. Apnoeas detected within 30 seconds after the onset of a GOR episode were defined GOR-induced Results: One-hundred-eighty-seven apnoeas out of 1523 were detected within 30” before and/or after the onset of a GOR episode. The frequency of apnoeas detected in the 30” after pH-GOR (0.148/min) was higher than the frequency detected in the 30”before (0.085/min; p=.04); even more, the frequency of apnoeas detected in the 30” after non-acid MII-GOR episodes (0.223/min) was significantly higher than the one detected in the 30” before (0.057/min; p=.000), whereas the frequency of apnoeas detected 30” before acid MII-GOR episodes (0.029/min) did not differ from the one detected after (0.109/min, p=.137). Furthermore we calculated -apnoea-frequency (defined as the difference between the frequency of apnoea after and before GOR for each type of GOR and for each patient) and we found that -apnoea-frequency of Na-MII-GOR (0.166/min) was significantly higher than those of pH-GOR (0.055/min; p=.025) and aMII-GOR (0.065/min; p=.007). No difference in the mean height nor in the mean duration was found between GOR episodes inducing and those non-inducing an apnoea. Conclusion: The analysis of physical and chemical features of GOR highlights that the most dramatic increase (approximately four-fold) in the frequency of apnoeas after GOR is due to non-acid GOR episodes. Non–acid GOR is prevalent soon after feeding, when the stomach is full of milk: thus, we can hypothesize that, in that period, the majority of GORs, beyond being non-acid, is huge enough to distend mechanically the mid-oesophagus, thus evoking an apnoea. This data could explain the clinical observation of an increase of AOP in the post-prandial period. Non-acid GOR is the main responsible for the variable amount of AOP induced by GOR: this novel finding must be taken into consideration when a therapeutic strategy for this common problem is planned.
The frequency of apnoeas in very preterm infants is strongly increased by non-acid gastro-oesophageal reflux.
CORVAGLIA, LUIGI TOMMASO;ZAMA, DANIELE;ACETI, ARIANNA;FALDELLA, GIACOMO
2010
Abstract
Background and aims: The relationship between apnoea of prematurity (AOP) and gastro-oesophageal reflux (GOR) has been frequently hypothesized. Both GOR and AOP occur frequently in preterm infants: actually, in clinical practice it is common to observe an increased frequency of AOP during postprandial periods, when the majority of GOR episodes also occurs. The widespread clinical perception that postprandial apnoeas in preterm infants can be related to GOR probably contributes to the well-known GOR over-treatment in this population. In a previous study, we found a significant increase of the frequency of AOP in the period following the onset of GOR, suggesting a possible causal relationship between GOR and AOP in a limited and variable proportion of AOP. We aim to evaluate whether physical and/or chemical features of gastro-oesophageal reflux (GOR) influence the relationship between GOR and apnoea of prematurity (AOP). Materials and methods: Fifty-eight preterm newborns (20 male) with gestational age ≤ 33 weeks were studied as they had recurrent apnoeas. None of them had malformation or major gastrointestinal problems, nor was taking drugs influencing gastrointestinal motility or gastric acidity. Each infant underwent a simultaneous recording of polysomnography (PSG) and combined impedance and pH monitoring (pH-MII). The investigator who analyzed pH-MII layouts was blind to the results of PSG, and vice versa. All the data, recorded during each postprandial period, were then separately analyzed. We analyze whether the correlation between GOR and AOP varies according to the acidity, duration and height of GOR episodes. All the episodes detected by MII with a concomitant decrease in pH to less than 4 are defined as acid MII-GOR (a-MII-GOR), while the episodes with a pH >4 are defined as non-acid MII-GOR (Na-MII-GOR). Acid GOR episodes recorded only by pH probe are defined a pH-GOR. PSG detects apneas by recording of breathing movement, nasal airflow, electrocardiogram and oxygen saturation. We considered as apnoeas each oral/nasal flow cessation lasting at least 5 seconds. Apnoeas were then classified as central (CA), obstructive (OA) and mixed (MA) depending on absence or presence of obstructed respiratory efforts. Apnoeas detected in the 1-minute time around the onset of each kind of GOR were further divided into apnoeas detected 30” before and 30” after the onset of GOR. Apnoeas detected within 30 seconds after the onset of a GOR episode were defined GOR-induced Results: One-hundred-eighty-seven apnoeas out of 1523 were detected within 30” before and/or after the onset of a GOR episode. The frequency of apnoeas detected in the 30” after pH-GOR (0.148/min) was higher than the frequency detected in the 30”before (0.085/min; p=.04); even more, the frequency of apnoeas detected in the 30” after non-acid MII-GOR episodes (0.223/min) was significantly higher than the one detected in the 30” before (0.057/min; p=.000), whereas the frequency of apnoeas detected 30” before acid MII-GOR episodes (0.029/min) did not differ from the one detected after (0.109/min, p=.137). Furthermore we calculated -apnoea-frequency (defined as the difference between the frequency of apnoea after and before GOR for each type of GOR and for each patient) and we found that -apnoea-frequency of Na-MII-GOR (0.166/min) was significantly higher than those of pH-GOR (0.055/min; p=.025) and aMII-GOR (0.065/min; p=.007). No difference in the mean height nor in the mean duration was found between GOR episodes inducing and those non-inducing an apnoea. Conclusion: The analysis of physical and chemical features of GOR highlights that the most dramatic increase (approximately four-fold) in the frequency of apnoeas after GOR is due to non-acid GOR episodes. Non–acid GOR is prevalent soon after feeding, when the stomach is full of milk: thus, we can hypothesize that, in that period, the majority of GORs, beyond being non-acid, is huge enough to distend mechanically the mid-oesophagus, thus evoking an apnoea. This data could explain the clinical observation of an increase of AOP in the post-prandial period. Non-acid GOR is the main responsible for the variable amount of AOP induced by GOR: this novel finding must be taken into consideration when a therapeutic strategy for this common problem is planned.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
