Assessment of three methods of pH probe positioning in preterm infants

Simple Formula for pH/Impedance Probe Positioning in Children-Time to Update Standard Practice?

OBJECTIVE

To develop a novel formula for pH probe placement with adequate accuracy.

METHODS

Children (3-18 y) undergoing pH-metry were prospectively evaluated. Their height and corrected pH probe position under X-ray (2 vertebrae above the diaphragm) was recorded and the linear-regression analysis was performed to derive a novel formula. Its accuracy was checked on an additional group of prospectively included children. The success rate of a newly developed formula was estimated and compared to the performance of previously used formulae. The difference in the suggested placement of the probe (cm from nostrils) was calculated.

RESULTS

Based on 670 children with pH probe placed under X-ray, the following formula was developed using the linear-regression analysis: L = 0.184x + 4.4 (cm) (L = probe placement depth, x = body height). Its accuracy was confirmed on additional 111 children resulting in almost 85% success rate. The formula showed significant difference in the suggested placement from formulae used previously: +4.9 ± 0.8 cm, +2.4 ± 0.1 cm, +0.7 ± 0.6 cm, +1.1 ± 0.4 cm, +1.8 ± 0.3 cm, +2.2 ± 0.5 cm from the one by the Strobel, Moreau, Wilson, Nowak, Staiano-Clouse formulae, and the GOSH table with the calculated success rates of 1.8%, 43.2%, 65.8%, 77.5%, 65.8% and 54.1%, respectively. A table suggesting placement depth based on the body height was developed.

CONCLUSION

The present formula provides 85% success of pH probe placement in children ≥ 3 y suggesting its use in routine practice. More data are needed to confirm that probe adjustment under X-ray is unnecessary.

Esophageal length in children: Reference data and a novel predictive equation

Minimal information exists on the length of the child's esophagus, namely the distance from the cricopharyngeus to the esophagogastric junction (EGJ). We aimed to investigate the relationship between esophageal length (EL) and the age, height, and weight of the child. Children undergoing upper gastrointestinal endoscopy between February 2019 and May 2021 at our institution were prospectively audited. Children with anatomical esophageal disorders were excluded. Endoscopic distances from the incisors to the cricopharyngeus and EGJ were obtained, and novel predictive equations derived to predict EL. Intra-observer agreement for endoscopic measurements showed an intra-class correlation coefficient of 0.99. A total of 290 children aged 0.4-17.3 years were included in the analysis; they were divided into a model development cohort (n = 261) and a model validation cohort (n = 29). Measured EL correlated best with height (r = 0.92) as compared to age (r = 0.90) or weight (r = 0.83). The optimal equation for predicting EL was 0.156 × height (cm) - 1.336 (adjusted R²  = 0.841); this had a success rate of 76% in the validation cohort. The optimal equation for predicting distance from incisors to EGJ was 0.199 × height (cm) + 6.470 (adjusted R²  = 0.889); this had a success rate of 69% in the validation cohort. This is the first study to report a predictive equation for estimating esophageal length in children. Accurate prediction of esophageal length may assist with clinical esophageal procedures in children such as nasogastric and pH probe placement.

Esophageal length: esophageal manometry remains superior to mathematical equations

BACKGROUND AND OBJECTIVES

Many mathematical equations based on height have been developed to estimate the esophageal length (EL) in children. The aim of this study was to confirm whether the preexisting and most frequently used equation by Strobel et al is accurate in calculating the EL in our pediatric population. Our secondary goal was to evaluate whether a new formula could be developed using our nonsurgical and surgical populations' data for the correlation between patients' height and measured EL by esophageal manometry (EM).

METHODS

From 2000 to 2009, 116 children between the ages of 3 and 18 years without previous esophageal surgery underwent EM (n = 31) at the Montreal Children's Hospital. During the same period, 55 EMs were performed on 34 children with a previous history of esophageal surgery. For both groups, we collected the following data: height, EL calculated by the Strobel formula, and EL measured by EM.

RESULTS

The Strobel equation was inaccurate in predicting the EL. The calculated EL was 3.0 ± 0.32 cm longer than the EM measurements (P < 0.001). The height (H) of nonsurgical children was found to be highly predictive of the lower esophageal sphincter location (L), and the derived linear regression equation is L = 0.216 (H) + 7.13 [r² = 0.85].

CONCLUSIONS

This study confirmed that the Strobel formula is not sufficiently accurate to predict EL in the pediatric population that is between 3 and 18 years old. A correlation exists between height and esophageal sphincter location position. If EM is unavailable, the use of a new mathematical equation like ours can be considered.

Diagnosis of gastro-oesophageal reflux in preterm infants: sonography vs. pH-monitoring

OBJECTIVES

To compare the ultrasound examination with pH-metry in order to evaluate the diagnostic accuracy of sonography for diagnosis of gastro-oesophageal reflux (GOR) in preterm infants.

METHODS

A prospective study was conducted on 31 premature infants <34 weeks with clinically diagnosed GOR. First, they underwent 24-hour pH-monitoring; successively, the sonographic assessment was performed within 12 h after pH-monitoring. The two operators who performed the pH-monitoring and sonography respectively, were unaware of each other's results.

RESULTS

Twenty-one patients (67.7%) had significant GOR with a reflux index >5 (GOR group). The median (range) reflux index in this group was 9.19% (6.04-20.1). Ten newborns (32.3%) did not have significant GOR with a reflux index <5. Sonography was positive for GOR in 8 patients (25.8%); all 8 infants with sonographic diagnosis of GOR had a reflux index >5. Therefore, sonographic diagnosis did not produce false positives. Sonography was negative in 23 newborns (74.2%); 13 of these were positive to pH-monitoring and may therefore be considered as false negatives. Respect to continuous 24-hour pH-monitoring, sonography showed a specificity of 100% but a very low sensitivity of 38% with a positive prediction value of 100% and a negative prediction value of 43%.

CONCLUSIONS

Sonography should not replace 24-hour pH monitoring for detecting GOR in preterm infants. However, sonography has a very high specificity and a positive predictive value of 100%. When clinicians suspect GOR in preterm infants, it could be useful for selection of cases to refer for pH-metry.

The relationship between somatic growth and in vivo esophageal segmental and sphincteric growth in human neonates

BACKGROUND

Measurement of aerodigestive tract length is an important determinant for accurate placement of esophageal probes and gavage tubes at the desired location. The relationship of esophageal body, upper esophageal sphincter (UES) and lower esophageal sphincter (LES) lengths with somatic growth in neonates is not well understood.

OBJECTIVES

Our objectives were to (1) evaluate a relationship between segmental esophageal lengths and somatic growth parameters and (2) ascertain the relationship between segmental esophageal lengths and gestational age (GA) and postmenstrual age (PMA) in preterm and full-term born human neonates.

DESIGN/METHODS

One hundred esophageal manometry studies were performed in 75 infants (30-60 weeks PMA) and the high-pressure zones of LES and UES identified. The distance from nares to LES and from nares to UES, esophageal body length, length of UES and LES derived from the manometry studies were correlated with somatic growth parameters. Growth rate of different esophageal segments was also determined in 26 subjects that underwent longitudinal studies. Analysis of variance and linear regression analysis were performed.

RESULTS

Seventy-five neonates of 23.0-40.6 weeks gestational age (0.6-4.4 kg) were studied at 29.1-58.6 weeks PMA (1.0-6.4 kg). Significant correlation (P < 0.001) of PMA and physical growth parameters with the growth of nares-LES (R = 0.8), esophageal body length (R = 0.6) and nares-UES (R = 0.4) were noted. Nares-to-LES length increased at a rate of 0.25 cm/wk PMA during 33.0-36.0 weeks of age.

CONCLUSIONS

In vivo esophageal segmental lengths correlated strongly with somatic growth parameters and PMA in neonates. We speculate that this approach has many practical applications with the use of esophageal probes and catheters.