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Positioning for prevention of infant gastroesophageal reflux
Positioning for prevention of infant gastroesophageal reflux A controlled, prospective comparison o f the use of the infant seat versus prone, head-elevated positioning in a harness was undertaken in 15 infants with gastroesophageal reflux, pH monitoring of the distal esophagus demonstrated less reflux in the harness than in the seat (P < 0.001) during 19 pairs of two-hour postprandial trials. This difference was the result of both fewer episodes (P < 0.001) and briefer episodes (P < 0.05). Prone-elevated positioning in the harness described is superior to positioning in an infant seat in the treatment o f gastroesophageal reflux in infants younger than 6 months. (J PEDtATR 103:534, 1983)
Susan R. Orenstein, M.D., and Peter F. Whitington, M.D. Memphis, Tenn.
GASTROESOPHAGEAL REFLUX is common in infants. At
best, it may be a benign developmental nuisance to parents and pediatricians. At worst, it may cause chronic pulmonary disease, esophagitis and peptic stricture, failure to thrive, and even death? Determining the optimal therapy for gastroesophageal reflux in infants is thus imperative. Antireflux therapy in adults includes upright posture, so that gravity may aid in the prevention of reflux and in the early clearance of refluxed material from the esophagus. Babies, unlike adults, cannot assume an upright posture; therefore, positional therapy in infants depends on a method of supporting them upright. Positioning in an infant seat has been the preferred method for supporting infants upright for years. 2,a Because our observation of babies with gastroesophageal reflux led us to suspect that the prone, head-elevated position might be superior to positioning in an infant seat in the treatment of reflux, we undertook a prospective, controlled comparison of the two positions. To support the infants in the prone, head-elevated position, we used a simple cloth harness. METHODS
Patients. The patient population comprised all children younger than 6 months who were referred to the gastroenterology service for evaluation f0~ gastroesophageal reflux during a five-month period and in whom reflux had been From the University o f Tennessee Center for the Health Sciences and the LeBonheur Children's Medical Center. Reprint requests." Susan R. Orenstein, M.D., LeBonheur Children's Medical Center, 848 Adams Ave., Memphis, TN 38103.
534
The Journal of P E D I A T R I C S
Table I. Clinical symptoms Symptom
Vomiting "Spells" (apnea, cyanosis, stiffening, mouthing) Respiratory tract (cough, pneumonia, bronchitis, abnormal findings on chest radiograph) Irritability, screaming Failure to thrive Hematemesis, stool occult blood Anorexia
I Patients (n = 15)
10 8 6 6 3 2 1
documented by preliminary overnight pH probe evaluation. Their parents gave informed consent to the study protocol, which was approved by the University of Tennessee Center for the Health Sciences Institutional Review Board. The patients were aged 2 weeks to 6 months, with a mean of 2.5 months. The most common symptoms were vomiting and various types of "spells" (Table I). Procedure. As preliminary evaluation, each infant's lower esophageal sphincter location and pressure were determined manometrically (Table II). The pH probe (1.4 'fiam" diameter, No. 508, Microelectrodes, Londonderry, NH) was then inserted transnasally to 2.5 to 3.0 cm above the upper border of the lower esophageal sphincter. Distal esophageal pH was recorded (Beckman Model 3500 Digital pH Meter, Irvine, CA, linked to Kipp & Zonen BD40 single-channel chart recorder, Holland) for at least 12 hours to document gastroesophageal reflux (Table II), defined as pH <4 for more than 10% of a postprandial period, which has been shown to be highly sensitive and
Volume 103 Number 4
Position and gastroesophageal reflux
5O
~
25 F
Z
~
2O
=7 b
o
I
5
'
lil s
15 F
0
H
A. GER TIME
Fig. 1. Five-week-old infant positioned in harness.
rn
s
N
B GER EPISODES
2C
2.5 2.0
specific for pathologic reflux? During this preliminary pH evaluation, routine care and handling were provided by the parents, who were given no instructions regarding positioning; the patients' hands were mitred as needed to prevent dislodgement of the probe. Up to four apple juice feedings of unspecified volume were given during this period. Each infant was then studied during paired, two-hour postprandial periods in an infant seat (Infanseat Babycarrier, Questor Juvenile Furniture Co., Los Angeles) elevated 60 degrees or in a cloth harness ( M R I Corp., Powell, T N ) (Fig. 1). The harness, when pinned to the mattress, supports an infant at any angle to which the mattress is elevated. The child may be placed in it either prone or supine; in our study, all were prone, with head elevated 30 to 45 degrees from horizontal. The study patients were placed in either the seat or harness as determined by lottery for the first two-hour period, and alternately in the two devices during successive periods. They were fed apple juice (pH <4.5) and thoroughly burped just before each trial. Consecutive paired trials in seat and harness were preceded b~r feeding of identical volumes of juice. Three infants were fed one or more feedings by brief nasogastric tube placement, because theY refused to take the specified amount of apple juice orally. Although the pH of the apple juice varied from 3.7 to 4.3, juice from a single container was fed during each pair of trials. The infants were left in the particular position continuously, except for brief removal for diaper change if that was required because of implacable fussiness. The diaper change time, less than three minutes in all cases, was eliminated from the 120-minute trial period, and an equal time added at t h e end. One such event occurred for each of three babies. The parents were discouraged from touching or offering a pacifier to the infants, although only manipulation of the infants' position was actually proscribed. Fifteen infants participated in 38 paired trials, 19 in the seat and 19 in the harness. Eight infants were placed first in the harness,
Ij
2C.
3O
10,
535
"7 1=
1.5 z 1C (2_ i-
1,C
0.5 !
oi
$
H
C. GER E P I S O D E S > 5 '
oi
H
D. LONGEST GER EPISODE
Fig. 2. Comparison of quantity of gastroesophageal reflux occurring during 19 pairs of trials in infant seat (S) and in prone head-elevated position in harness (11). A, Percent of time (mean +_ SEM) with distal esophageal pH <4 (37.4 _+ 6.2 vs 7.9 _+ 2.-3; P<0.001). B, Number of episodes of pH <4 (19.6 __+3.5 vs 5.2 _+ 1.1; P < 0.001 ). C, Number of such episodes lasting longer than five minutes (1.9 +- 0.6 vs 0.6 -+ 0.2; P < 0.05). D, Duration of longest episode in each two-hour postprandial period (13.1 + 5.0 vs 5.0 _+ 1.7; P < 0.05).
Table II. Preliminary evaluation for gastroesophageal reflux Diagnostic test
Barium esophagram (n = 13) Normal Minimal reflux Reflux to cervical esophagus Aspiration Manometry (n = 15) LESP 0 to 4 mm Hg LESP 5 to 9 mm Hg LESP 10 to 14 mm Hg LESPI5to 19mmHg LESP >20 mm Hg 12-Hour pH probe (n = 15) >10% pp time in reflux >5 episodes pp reflux Any pp reflux episodes >5 min Any pp reflux episode >20 min
Patients
5 2 4 2 0 4 5 5 1 15 13 11 5
LESP, Lower esophageal sphincter pressure; pp, two-hour postprandial period.
536
Orenstein and Whitington
The Journal of Pediatrics October 1983
seat and the harness for each of these measures was evaluated using the Student t test for paired observations; the Student t test f o r unpaired observations was used to determine the significance of group mean differences. RESULTS The harness was associated with a smaller percentage of postprandial gastroesophageal reflux time than was the infant seat in every pair of trials except one (Fig. 2, A). This reduction of reflux time resulted from both shorter individual episodes (Fig. 2, C and D) and fewer episodes (Fig. 2, B). The occurrence of more reflux in the seat than in the harness held true for the six patients older than 2 months (22.3% vs 7.4%, P < 0.005) as well as for the nine younger ones (48.4% vs 8.3%, P < 0.01). The two age groups did not differ in the percent Of reflux time experienced in the harness (P > 0.2), but the younger infants experienced significantly more reflux than the older ones in the seat (P < 0.05). In addition to the objective experimental data, several subjective, retrospective, and unquantified observations were made. The infants slept in the harness more than in the seat; this was especially true for the youngest ones, who would often immediately become quiet and go to sleep when placed in the harness. The infants were fussier in the seat, although those close to 6 months of age had some fussiness in the harness, and sometimes appeared to feel constrained by it when awake. Although considerable effort was applied to initial upright positioning in the seat, the babies resisted such effort, and slumped, a finding particularly marked among the youngest ones. DISCUSSION
Fig. 3. Radiographic demonstration of relative position of gastric air bubble and gastroesophageal junction in 1-month-old infant positioned in infant seat at 60 degrees elevation (A) and harness at 30 degrees elevation (B). Arrow indicates location of the gastroesophageal junction, which is submerged in seat but not in harness.
seven first in the seat. One of us (S.O.) observed the study patients throughout the 72 test hours. Recordings of distal esophageal pH were analyzed for four measurements commonly used in assessing gastroesophageal reflux: percent of time during the two-hour Postprandial period in which pH was <4.0, number of episodes of pH <4.0, number of such episodes lasting longer than five minutes, and duration of the longest episode2, 5 The significance of the differences between the
Our study demonstrates the superiority of the proneelevated position over traditional positioning in an infant seat tbr decreasing reflux quantity in children younger than 6 m o t h s of age. Prone-elevated positioning in a harness such as we have described may prevent morbidity from gastroesophageal reflux and from surgical intervention in patients in whom conservative therapy in an infant seat might have proved unsuccessful. Since Carre's 2 retrospective, subjective evaluation in 1960 of the utility of upright positioning in an infant seat, the seat has been the standard for positional treatment of gastroesophageal reflux in infants. In 1982, Meyers and Herbst 6 presented data suggesting that the 30-degree prone-elevated position was superior to the "upright" position, which utilized an infant seat for children younger than 1 year and a chair for older ones. Their study included a diverse group of children (age range unspecified, mean I 1.6 months, SEM 3.0 months) as well as diverse means of
Volume 103 Number 4
establishing an "upright" position; these differences make comparison of their data with ours difficult. However, the inference may be made from their data that the proneelevated position is superior to the traditional infant seat in preventing gastroesophageal reflux. Our results confirm this suggestion in children younger than 6 months of age. The crossover design used in our study eliminates variability resulting from differences in the subjects, and the order of the paired trials was determined randomly by lottery to eliminate a possible effect of trial order or time of day. The volume of feeding for pairs of trials was held constant to eliminate any effect on quantity of reflux? "2 Apple juice was used because of our observation during preliminary trials that an infant who had been fed milk could vomit during the postprandial period without registering a drop in esophageal pH. A possible selection bias in our study is that the patients were referred for evaluation, either by pediatricians or pediatric residents. Infants with gastroesophageal reflux who responded readily to treatment in an infant seat might have been less likely to be referred. There are several possible explanations for the superiority of the harness over the seat in children younger than 6 months. First, the posterior gastroesophageal junction is more likely to be submerged in a 60-degree sitting position than in a prone, head-elevated position. The latter position, on the contrary, would elevate the gastroesophageal junction above the air-fluid level in the stomach, producing burps rather than reflux during sphincter incompetence and aiding esophageal clearance of refluxed material. This fact is graphically demonstrated in the radiographs in Fig. 3, in which the gastroesophageal junction in a 1-month-old child is shown to be below the gastric air-fluid level while the patient is in the seat, and above it in the harness. Second, infants of this age have reduced truncal tone, and even rigorous attempts at propping them upright in the seat are often unsuccessful. The slump thus produced tends to submerge the posterior gastroesophageal junction far-
Position and gastroesophageal reflux
537
ther. This hypothetical effect of immaturity in truncal tone is substantiated by the greater amount of reflux in the seat in the infants younger than 2 months. Third, slumping posture probably increases intraabdominal pressure, one factor that may increase gastroesophageal reflux. 7 Fourth, we observed that the infants slept more in the harness, and many investigators have noted decreased reflux during sleep? '~ It is possible, on the other hand, that the increased sleep was a secondary effect caused by the relief of symptoms of reflux in that position. Thus, prone-elevated positioning in a harness is more effective than the standard positioning in an infant seat in decreasing gastroesophageal reflux in infants younger than 6 months of age. The harness is cheap, lightweight, and easily portable. When adjustable hospital beds are not available, the bed may be elevated on blocks, or the mattress itself supported at an angle. Postprandial sleep periods are ideally suited to the harness, and during waking periods infants may be situated so that they can see over the end of the mattress as well as to either side. REFERENCES 1. Herbst J J: Gastroesophageal reflux. J PEDIATR 98:859, 1981. 2. Carte IJ: Postural treatment of children with a partial thoracic stomach ("hiatus hernia"). Arch Dis Child 35:569, 1960. 3. Silverman A, Roy CC, Cozzetto FJ: Pediatric clinical gastroenterology. St. Louis, 1971, CV Mosby, p 120. 4. Euler AR, Byrne WJ: Twenty-four-hour intraluminal pH probe testing: A comparative analysis. Gastroenterology 80:957, 1981. 5. Sondheimer JM: Continuous monitoring of distal esophageal pH: A diagnostic test for gastroesophageal reflux in infants. J PEDIATR96:804, 1980. 6. Meyers WF, Herbst J J: Effectivenessof positioning therapy for gastroesophageal reflux. Pediatrics 69:768, 1982. 7. Dodds WJ, Hogan WJ, Helm JF, et ah Pathogenesisof reflux esophagitis. Gastroenterology 81:376, 1981. 8. Johnson LF: New concepts and methods in the study and treatment of gastroesophageal reflux disease. Med Clin North Am 65:1195, 1981.
Susan R. Orenstein, M.D., and Peter F. Whitington, M.D. Memphis, Tenn.
GASTROESOPHAGEAL REFLUX is common in infants. At
best, it may be a benign developmental nuisance to parents and pediatricians. At worst, it may cause chronic pulmonary disease, esophagitis and peptic stricture, failure to thrive, and even death? Determining the optimal therapy for gastroesophageal reflux in infants is thus imperative. Antireflux therapy in adults includes upright posture, so that gravity may aid in the prevention of reflux and in the early clearance of refluxed material from the esophagus. Babies, unlike adults, cannot assume an upright posture; therefore, positional therapy in infants depends on a method of supporting them upright. Positioning in an infant seat has been the preferred method for supporting infants upright for years. 2,a Because our observation of babies with gastroesophageal reflux led us to suspect that the prone, head-elevated position might be superior to positioning in an infant seat in the treatment of reflux, we undertook a prospective, controlled comparison of the two positions. To support the infants in the prone, head-elevated position, we used a simple cloth harness. METHODS
Patients. The patient population comprised all children younger than 6 months who were referred to the gastroenterology service for evaluation f0~ gastroesophageal reflux during a five-month period and in whom reflux had been From the University o f Tennessee Center for the Health Sciences and the LeBonheur Children's Medical Center. Reprint requests." Susan R. Orenstein, M.D., LeBonheur Children's Medical Center, 848 Adams Ave., Memphis, TN 38103.
534
The Journal of P E D I A T R I C S
Table I. Clinical symptoms Symptom
Vomiting "Spells" (apnea, cyanosis, stiffening, mouthing) Respiratory tract (cough, pneumonia, bronchitis, abnormal findings on chest radiograph) Irritability, screaming Failure to thrive Hematemesis, stool occult blood Anorexia
I Patients (n = 15)
10 8 6 6 3 2 1
documented by preliminary overnight pH probe evaluation. Their parents gave informed consent to the study protocol, which was approved by the University of Tennessee Center for the Health Sciences Institutional Review Board. The patients were aged 2 weeks to 6 months, with a mean of 2.5 months. The most common symptoms were vomiting and various types of "spells" (Table I). Procedure. As preliminary evaluation, each infant's lower esophageal sphincter location and pressure were determined manometrically (Table II). The pH probe (1.4 'fiam" diameter, No. 508, Microelectrodes, Londonderry, NH) was then inserted transnasally to 2.5 to 3.0 cm above the upper border of the lower esophageal sphincter. Distal esophageal pH was recorded (Beckman Model 3500 Digital pH Meter, Irvine, CA, linked to Kipp & Zonen BD40 single-channel chart recorder, Holland) for at least 12 hours to document gastroesophageal reflux (Table II), defined as pH <4 for more than 10% of a postprandial period, which has been shown to be highly sensitive and
Volume 103 Number 4
Position and gastroesophageal reflux
5O
~
25 F
Z
~
2O
=7 b
o
I
5
'
lil s
15 F
0
H
A. GER TIME
Fig. 1. Five-week-old infant positioned in harness.
rn
s
N
B GER EPISODES
2C
2.5 2.0
specific for pathologic reflux? During this preliminary pH evaluation, routine care and handling were provided by the parents, who were given no instructions regarding positioning; the patients' hands were mitred as needed to prevent dislodgement of the probe. Up to four apple juice feedings of unspecified volume were given during this period. Each infant was then studied during paired, two-hour postprandial periods in an infant seat (Infanseat Babycarrier, Questor Juvenile Furniture Co., Los Angeles) elevated 60 degrees or in a cloth harness ( M R I Corp., Powell, T N ) (Fig. 1). The harness, when pinned to the mattress, supports an infant at any angle to which the mattress is elevated. The child may be placed in it either prone or supine; in our study, all were prone, with head elevated 30 to 45 degrees from horizontal. The study patients were placed in either the seat or harness as determined by lottery for the first two-hour period, and alternately in the two devices during successive periods. They were fed apple juice (pH <4.5) and thoroughly burped just before each trial. Consecutive paired trials in seat and harness were preceded b~r feeding of identical volumes of juice. Three infants were fed one or more feedings by brief nasogastric tube placement, because theY refused to take the specified amount of apple juice orally. Although the pH of the apple juice varied from 3.7 to 4.3, juice from a single container was fed during each pair of trials. The infants were left in the particular position continuously, except for brief removal for diaper change if that was required because of implacable fussiness. The diaper change time, less than three minutes in all cases, was eliminated from the 120-minute trial period, and an equal time added at t h e end. One such event occurred for each of three babies. The parents were discouraged from touching or offering a pacifier to the infants, although only manipulation of the infants' position was actually proscribed. Fifteen infants participated in 38 paired trials, 19 in the seat and 19 in the harness. Eight infants were placed first in the harness,
Ij
2C.
3O
10,
535
"7 1=
1.5 z 1C (2_ i-
1,C
0.5 !
oi
$
H
C. GER E P I S O D E S > 5 '
oi
H
D. LONGEST GER EPISODE
Fig. 2. Comparison of quantity of gastroesophageal reflux occurring during 19 pairs of trials in infant seat (S) and in prone head-elevated position in harness (11). A, Percent of time (mean +_ SEM) with distal esophageal pH <4 (37.4 _+ 6.2 vs 7.9 _+ 2.-3; P<0.001). B, Number of episodes of pH <4 (19.6 __+3.5 vs 5.2 _+ 1.1; P < 0.001 ). C, Number of such episodes lasting longer than five minutes (1.9 +- 0.6 vs 0.6 -+ 0.2; P < 0.05). D, Duration of longest episode in each two-hour postprandial period (13.1 + 5.0 vs 5.0 _+ 1.7; P < 0.05).
Table II. Preliminary evaluation for gastroesophageal reflux Diagnostic test
Barium esophagram (n = 13) Normal Minimal reflux Reflux to cervical esophagus Aspiration Manometry (n = 15) LESP 0 to 4 mm Hg LESP 5 to 9 mm Hg LESP 10 to 14 mm Hg LESPI5to 19mmHg LESP >20 mm Hg 12-Hour pH probe (n = 15) >10% pp time in reflux >5 episodes pp reflux Any pp reflux episodes >5 min Any pp reflux episode >20 min
Patients
5 2 4 2 0 4 5 5 1 15 13 11 5
LESP, Lower esophageal sphincter pressure; pp, two-hour postprandial period.
536
Orenstein and Whitington
The Journal of Pediatrics October 1983
seat and the harness for each of these measures was evaluated using the Student t test for paired observations; the Student t test f o r unpaired observations was used to determine the significance of group mean differences. RESULTS The harness was associated with a smaller percentage of postprandial gastroesophageal reflux time than was the infant seat in every pair of trials except one (Fig. 2, A). This reduction of reflux time resulted from both shorter individual episodes (Fig. 2, C and D) and fewer episodes (Fig. 2, B). The occurrence of more reflux in the seat than in the harness held true for the six patients older than 2 months (22.3% vs 7.4%, P < 0.005) as well as for the nine younger ones (48.4% vs 8.3%, P < 0.01). The two age groups did not differ in the percent Of reflux time experienced in the harness (P > 0.2), but the younger infants experienced significantly more reflux than the older ones in the seat (P < 0.05). In addition to the objective experimental data, several subjective, retrospective, and unquantified observations were made. The infants slept in the harness more than in the seat; this was especially true for the youngest ones, who would often immediately become quiet and go to sleep when placed in the harness. The infants were fussier in the seat, although those close to 6 months of age had some fussiness in the harness, and sometimes appeared to feel constrained by it when awake. Although considerable effort was applied to initial upright positioning in the seat, the babies resisted such effort, and slumped, a finding particularly marked among the youngest ones. DISCUSSION
Fig. 3. Radiographic demonstration of relative position of gastric air bubble and gastroesophageal junction in 1-month-old infant positioned in infant seat at 60 degrees elevation (A) and harness at 30 degrees elevation (B). Arrow indicates location of the gastroesophageal junction, which is submerged in seat but not in harness.
seven first in the seat. One of us (S.O.) observed the study patients throughout the 72 test hours. Recordings of distal esophageal pH were analyzed for four measurements commonly used in assessing gastroesophageal reflux: percent of time during the two-hour Postprandial period in which pH was <4.0, number of episodes of pH <4.0, number of such episodes lasting longer than five minutes, and duration of the longest episode2, 5 The significance of the differences between the
Our study demonstrates the superiority of the proneelevated position over traditional positioning in an infant seat tbr decreasing reflux quantity in children younger than 6 m o t h s of age. Prone-elevated positioning in a harness such as we have described may prevent morbidity from gastroesophageal reflux and from surgical intervention in patients in whom conservative therapy in an infant seat might have proved unsuccessful. Since Carre's 2 retrospective, subjective evaluation in 1960 of the utility of upright positioning in an infant seat, the seat has been the standard for positional treatment of gastroesophageal reflux in infants. In 1982, Meyers and Herbst 6 presented data suggesting that the 30-degree prone-elevated position was superior to the "upright" position, which utilized an infant seat for children younger than 1 year and a chair for older ones. Their study included a diverse group of children (age range unspecified, mean I 1.6 months, SEM 3.0 months) as well as diverse means of
Volume 103 Number 4
establishing an "upright" position; these differences make comparison of their data with ours difficult. However, the inference may be made from their data that the proneelevated position is superior to the traditional infant seat in preventing gastroesophageal reflux. Our results confirm this suggestion in children younger than 6 months of age. The crossover design used in our study eliminates variability resulting from differences in the subjects, and the order of the paired trials was determined randomly by lottery to eliminate a possible effect of trial order or time of day. The volume of feeding for pairs of trials was held constant to eliminate any effect on quantity of reflux? "2 Apple juice was used because of our observation during preliminary trials that an infant who had been fed milk could vomit during the postprandial period without registering a drop in esophageal pH. A possible selection bias in our study is that the patients were referred for evaluation, either by pediatricians or pediatric residents. Infants with gastroesophageal reflux who responded readily to treatment in an infant seat might have been less likely to be referred. There are several possible explanations for the superiority of the harness over the seat in children younger than 6 months. First, the posterior gastroesophageal junction is more likely to be submerged in a 60-degree sitting position than in a prone, head-elevated position. The latter position, on the contrary, would elevate the gastroesophageal junction above the air-fluid level in the stomach, producing burps rather than reflux during sphincter incompetence and aiding esophageal clearance of refluxed material. This fact is graphically demonstrated in the radiographs in Fig. 3, in which the gastroesophageal junction in a 1-month-old child is shown to be below the gastric air-fluid level while the patient is in the seat, and above it in the harness. Second, infants of this age have reduced truncal tone, and even rigorous attempts at propping them upright in the seat are often unsuccessful. The slump thus produced tends to submerge the posterior gastroesophageal junction far-
Position and gastroesophageal reflux
537
ther. This hypothetical effect of immaturity in truncal tone is substantiated by the greater amount of reflux in the seat in the infants younger than 2 months. Third, slumping posture probably increases intraabdominal pressure, one factor that may increase gastroesophageal reflux. 7 Fourth, we observed that the infants slept more in the harness, and many investigators have noted decreased reflux during sleep? '~ It is possible, on the other hand, that the increased sleep was a secondary effect caused by the relief of symptoms of reflux in that position. Thus, prone-elevated positioning in a harness is more effective than the standard positioning in an infant seat in decreasing gastroesophageal reflux in infants younger than 6 months of age. The harness is cheap, lightweight, and easily portable. When adjustable hospital beds are not available, the bed may be elevated on blocks, or the mattress itself supported at an angle. Postprandial sleep periods are ideally suited to the harness, and during waking periods infants may be situated so that they can see over the end of the mattress as well as to either side. REFERENCES 1. Herbst J J: Gastroesophageal reflux. J PEDIATR 98:859, 1981. 2. Carte IJ: Postural treatment of children with a partial thoracic stomach ("hiatus hernia"). Arch Dis Child 35:569, 1960. 3. Silverman A, Roy CC, Cozzetto FJ: Pediatric clinical gastroenterology. St. Louis, 1971, CV Mosby, p 120. 4. Euler AR, Byrne WJ: Twenty-four-hour intraluminal pH probe testing: A comparative analysis. Gastroenterology 80:957, 1981. 5. Sondheimer JM: Continuous monitoring of distal esophageal pH: A diagnostic test for gastroesophageal reflux in infants. J PEDIATR96:804, 1980. 6. Meyers WF, Herbst J J: Effectivenessof positioning therapy for gastroesophageal reflux. Pediatrics 69:768, 1982. 7. Dodds WJ, Hogan WJ, Helm JF, et ah Pathogenesisof reflux esophagitis. Gastroenterology 81:376, 1981. 8. Johnson LF: New concepts and methods in the study and treatment of gastroesophageal reflux disease. Med Clin North Am 65:1195, 1981.