Pediatric Pulmonology 13:169-171 (1992)
Apnea and Periodic Breathing in Healthy Full-Term Infants, 12-18 Months of Age Dorothy H. Kelly, MD, Linda Riordan, YD, and Michael J. Smith Summary. Many children older than 12 months of age are now on home monitors. Home pneumograms performed on normal infants have established standards, and have been used to evaluate infants during their first year. However, no standards have been described for infants older than 12 months. We, therefore, recordedthe standard pneumogram on 88 full-term healthy infants who were 12-1 8 months of age. We analyzed the recordings for average respiratoryand heart rates, apnea ( 2 6 seconds) density, longest apnea, periodic breathing, and bradycardia for 12 hours. We compared the values in males vs. females and in infants 12-14.9 months vs. 15.0-18.0 months of age. Since there was no difference in any parameter measured in any group, we combined the values to determine the normal values for this population. Pediatr @) 1992 Wiley-Liss. Inc. Pulmonol. 1992; 13:16%171. Key words: Apnea density; longest apnea; bradycardia.
INTRODUCTION
For many years, studies have shown that chronic, prolonged apnea in infants has some correlation with death'.2 as well as with certain long-term neurologic abnormalities.' Recently, further studies have indicated that an increased incidence of apnea and bradycardia is found in a group of infants who died of sudden infant death syndrome (SIDS).4 Because of the reports that some infants with apnea unless a treatable cause for an apneic event can be found, these infants are usually monitored at home for prolonged apnea and for bradycardia. Some of the patients continue to have apnea and/or bradycardia, documented on physiologic recordings of the alarms,'.' after they reach 12 months of age. While normal values for apnea, bradycardia, and periodic breathing have been published for infants under 12 months of none have been reported for those > I year. Therefore, this study was undertaken to provide normative data in infants 12-1 8 months of age. MATERIALS AND METHODS
Heart and respiratory rates and respiratory patterns of 88 normal, full-term infants (Table l ) , who had no personal or family history of apnea or bradycardia, were recorded for 12 hours onto magnetic tape by a multichannel recorder geared to 1/16 of real time (Oxford Medilog Inc., Clearwater, FL). We used a cardiorespiratory monitor under parental supervision and permission. The tapes were played back by a PMD 12, and a hard copy was obtained by a high-frequency spray pen recorder (Mingograf 34, Elema-Schonader AB, Stockholm, Sweden). Both the playback unit and Mingograf 0 1992 Wiley-Liss, Inc.
were calibrated prior to the playing of each tape for both speed and heart rate trend line position. Episodes of bradycardia, apnea, and periodic breathing (PB), as well as the percent PB, the longest episode of PB, the number of episodes of PB, the average duration of PB, and apnea density were among the data obtained by computer analysis of the r e ~ o r d i n g Based .~ on the values of these parameters, we obtained means, standard deviations, medians, and ranges for the 12-18 month age group. We further subdivided the subjects into two age categories (52.0-64.9 weeks and 65.0-78.0 weeks) and compared the median or means between the two groups. The recordings were analyzed by a computer program as previously de~cribed.~," We defined bradycardia as G50 heart beatshin for 2 5 seconds. We chose this value, becausc it is half the mean rate at this age. In our previous report on infants up to 12 months of age,' bradycardia as a function of age was defined: heart rate S80 beats/min for a10 seconds in 0.0-4.0week old infants, G70 beats/min for 3 1 0 seconds in 4.1-12.0 week old infants, G60 beatshin for 310 seconds in 12.1-26.0
From the Pediatric Pulmonology Unit, Massachusetts General Hospital, Boston, Massachusetts. Received December 28, I99 I ; (revision) accepted for publication March 6. 1992. This research was partially supported by grants from the F d and Drug Administration and The Sudden Infant Death Alliance. Address correspondence and reprint requests to Dr. D.H. Kelly, Pediatric Pultnonolopy Unit, Massachusetts General Hospital. Boston, MA 021 14.
170
Kelly et al.
TABLE 1-Characteristics of 88 Normal Infants, 12.0-18.0 Months (52.0-78.0 weeks) of Age Gestational age (weeks) Chronological age (weeks) Birth weight (kg) Heart rate (BPM) Respiratory ratelmin Quiet time (minutes)
Mean
S.D.
40.0
f 0.4
62.7
f 5.5
3.7
f 0.5
ject, 50 of the 88 pauses lasted 10 seconds or longer. No bradycardia of 650 beats/min for 5 seconds or longer was found in any of these healthy infants. The median values for all parameters of periodic breathing were similar to those found in 16 week old and older infant^.^ DISCUSSION
weeks old infants, and 6 5 5 beats/min for 2 10 seconds in 26.1-52.0 weeks old infants. For the age group presently investigated, we defined apnea as a cessation of breathing for 3 6 seconds, unless it was apnea in periodic breathing, in which case it was defined as 2 3 seconds. Apnea density was defined as the total minutes of apnea 2 6 seconds/100 min of quiet time. Periodic breathing was defined as before:’ three episodes of apnea 2 3 seconds with less than 20 seconds of respiration between the episodes of apnea.
Nocturnal recordings of respiration and electrocardiograms (ECG) have yielded normal values for measurements of variability in a population of healthy infants, 12- 18 months of age. The longest apnea (17 seconds) in this population of infants was several seconds longer than that described .~~ have ~ previously for infants in their first y e a r ~ f l i f eWe found that after 4-5 months all PB parameters remain stable through 18 months of age. No episodes of bradycardia as defined in this study were seen in any infant. However, because we found abrupt “idiopathic” severe bradycardia in a population of infants who have been recorded at the time of death or resuscitation, three of whom died of unknown causes, we believe that bradycardia may be an important mechanism of death in infants and should be studied in various infant age categories of in order to establish normative data. One of the infants who was recorded at the time of death was 13 months of age. In the present study of 12-18 month old normal infants, no bradycardia (650BPM for 2 5 seconds) occurred during the 12 hour recordings. Further studies will be needed to determine if any significant physiologic changes (such as oxyhemoglobin desaturation)occur during the slightly longer sleep apneas found in this older age category of infants. In conclusion, healthy, full-term infants between the ages of 12 and 18 months frequently experience relatively short sleep apnea (6 to 13 seconds), but rarely longer than 16 seconds. Percent periodic breathing in this population is similar to that in 5-12 month old infants. Bradycardia, as defined earlier, was not found in these healthy infants. Normative mean heart rate and respiratory rate by I2 hour recordings were determined.
RESULTS
REFERENCES
111.4
Tt_
11.1
32.3
Tt_
4.9
t 0.4
330.4
TABLE 2-Data on Apnea and Periodic Breathing (PB) in 88 Normal Infants. 12-18 Months of Age ~
~
Mean
Median
Range
* 0.41
0.49
5
3.88
10.55
0-1.6 0-17.0
0.29 0.46
Tt_
0.50 0.54
0.00 0.25
0-2.5 0-2.4
0.38
f 0.61
0.00
(L2.9
0.36
* 0.39
0.23
0-1 .4
~~
Apnea density Longest apnea (seconds) Percent PB Longest episode of PB (minutes) Episodes of PB/100 min of quiet time Average duration of PB episodes (minutes)
SD
0.50 9.60
?
All parameters of heart rate and respiratory rate were analyzed for the entire group of 88 12.0-18.0 month old subjects, for the two age-subsets, and for males vs. females. The mean and median values were not different between age subgroups and between sexes. Therefore, the values for all infants in this study were combined for the final results (Table 2). Nineteen apneic spells > I 2 seconds (in 21.6% of infants) were recorded, one lasting 16.2 and two 17 seconds. Taking the longest apneic episode from each sub-
Steinschneider A. Prolonged apnea and the sudden infant death syndrome: Clinical and laboratory observations. Pediatrics. 1972; 60:64&653. Oren J , Kelly D, Shannon DC. Identification of a high risk group for SIDS among infants who were resuscitated for sleep apnea. Pediatrics. 1986; 77:495499. Deykin E, Bauman ML, Kelly DH, HsiehCC, Shannon D. Apnea of infancy and subsequent neurologic, cognitive, and behavioral status. Pediatrics. 1984; 73:638445. Kelly DH, Golub H, Carley D, Shannon DC. Pneumograrns in infants who subsequently died of SIDS. J Pediatr. 1986; 109:249259.
Apnea and Periodic Breathing 5. Kelly DH, Pathak A, Meny R. Sudden severe bradycardia in infancy. Pediatr Pulmonol. 1991; l0:199-204. 6. Kelly DH. Home Monitoring. In: Beckman RC, Brouillette RT, Hunt CF, eds. Respiratory Control Disorders in Infants and Children. Baltimore: Williams & Wilkins, In Press. 7. Kelly DH, Stellwagon LM, Kaitz E, Shannon DC. Apnea and periodic breathing in normal full-term infants during the first twelve months. Pediatr Pulrnonol. 1985; 1:215-219.
171
8. Hunt CE, Brouillctte RT, Hanson D, David RJ, Stein IM, Weissbluth M. Home pneumograms in normal infants. J Pediatr. 1985; 10655 I . 9. Stein IM, White A. kennedy JL, Merisalo RL, Chernoff H, Gould JB. Apnea recordings of healthy infants at 40,44, and 52 weeks postconception. Pediatrics. 1979; 63:724-730. 10. Kelly DH, Golub H, Shannon DC. Computer analysis of pneumograms. Am Rev Respir Dis. 1984; 129: 208.
Apnea and Periodic Breathing in Healthy Full-Term Infants, 12-18 Months of Age Dorothy H. Kelly, MD, Linda Riordan, YD, and Michael J. Smith Summary. Many children older than 12 months of age are now on home monitors. Home pneumograms performed on normal infants have established standards, and have been used to evaluate infants during their first year. However, no standards have been described for infants older than 12 months. We, therefore, recordedthe standard pneumogram on 88 full-term healthy infants who were 12-1 8 months of age. We analyzed the recordings for average respiratoryand heart rates, apnea ( 2 6 seconds) density, longest apnea, periodic breathing, and bradycardia for 12 hours. We compared the values in males vs. females and in infants 12-14.9 months vs. 15.0-18.0 months of age. Since there was no difference in any parameter measured in any group, we combined the values to determine the normal values for this population. Pediatr @) 1992 Wiley-Liss. Inc. Pulmonol. 1992; 13:16%171. Key words: Apnea density; longest apnea; bradycardia.
INTRODUCTION
For many years, studies have shown that chronic, prolonged apnea in infants has some correlation with death'.2 as well as with certain long-term neurologic abnormalities.' Recently, further studies have indicated that an increased incidence of apnea and bradycardia is found in a group of infants who died of sudden infant death syndrome (SIDS).4 Because of the reports that some infants with apnea unless a treatable cause for an apneic event can be found, these infants are usually monitored at home for prolonged apnea and for bradycardia. Some of the patients continue to have apnea and/or bradycardia, documented on physiologic recordings of the alarms,'.' after they reach 12 months of age. While normal values for apnea, bradycardia, and periodic breathing have been published for infants under 12 months of none have been reported for those > I year. Therefore, this study was undertaken to provide normative data in infants 12-1 8 months of age. MATERIALS AND METHODS
Heart and respiratory rates and respiratory patterns of 88 normal, full-term infants (Table l ) , who had no personal or family history of apnea or bradycardia, were recorded for 12 hours onto magnetic tape by a multichannel recorder geared to 1/16 of real time (Oxford Medilog Inc., Clearwater, FL). We used a cardiorespiratory monitor under parental supervision and permission. The tapes were played back by a PMD 12, and a hard copy was obtained by a high-frequency spray pen recorder (Mingograf 34, Elema-Schonader AB, Stockholm, Sweden). Both the playback unit and Mingograf 0 1992 Wiley-Liss, Inc.
were calibrated prior to the playing of each tape for both speed and heart rate trend line position. Episodes of bradycardia, apnea, and periodic breathing (PB), as well as the percent PB, the longest episode of PB, the number of episodes of PB, the average duration of PB, and apnea density were among the data obtained by computer analysis of the r e ~ o r d i n g Based .~ on the values of these parameters, we obtained means, standard deviations, medians, and ranges for the 12-18 month age group. We further subdivided the subjects into two age categories (52.0-64.9 weeks and 65.0-78.0 weeks) and compared the median or means between the two groups. The recordings were analyzed by a computer program as previously de~cribed.~," We defined bradycardia as G50 heart beatshin for 2 5 seconds. We chose this value, becausc it is half the mean rate at this age. In our previous report on infants up to 12 months of age,' bradycardia as a function of age was defined: heart rate S80 beats/min for a10 seconds in 0.0-4.0week old infants, G70 beats/min for 3 1 0 seconds in 4.1-12.0 week old infants, G60 beatshin for 310 seconds in 12.1-26.0
From the Pediatric Pulmonology Unit, Massachusetts General Hospital, Boston, Massachusetts. Received December 28, I99 I ; (revision) accepted for publication March 6. 1992. This research was partially supported by grants from the F d and Drug Administration and The Sudden Infant Death Alliance. Address correspondence and reprint requests to Dr. D.H. Kelly, Pediatric Pultnonolopy Unit, Massachusetts General Hospital. Boston, MA 021 14.
170
Kelly et al.
TABLE 1-Characteristics of 88 Normal Infants, 12.0-18.0 Months (52.0-78.0 weeks) of Age Gestational age (weeks) Chronological age (weeks) Birth weight (kg) Heart rate (BPM) Respiratory ratelmin Quiet time (minutes)
Mean
S.D.
40.0
f 0.4
62.7
f 5.5
3.7
f 0.5
ject, 50 of the 88 pauses lasted 10 seconds or longer. No bradycardia of 650 beats/min for 5 seconds or longer was found in any of these healthy infants. The median values for all parameters of periodic breathing were similar to those found in 16 week old and older infant^.^ DISCUSSION
weeks old infants, and 6 5 5 beats/min for 2 10 seconds in 26.1-52.0 weeks old infants. For the age group presently investigated, we defined apnea as a cessation of breathing for 3 6 seconds, unless it was apnea in periodic breathing, in which case it was defined as 2 3 seconds. Apnea density was defined as the total minutes of apnea 2 6 seconds/100 min of quiet time. Periodic breathing was defined as before:’ three episodes of apnea 2 3 seconds with less than 20 seconds of respiration between the episodes of apnea.
Nocturnal recordings of respiration and electrocardiograms (ECG) have yielded normal values for measurements of variability in a population of healthy infants, 12- 18 months of age. The longest apnea (17 seconds) in this population of infants was several seconds longer than that described .~~ have ~ previously for infants in their first y e a r ~ f l i f eWe found that after 4-5 months all PB parameters remain stable through 18 months of age. No episodes of bradycardia as defined in this study were seen in any infant. However, because we found abrupt “idiopathic” severe bradycardia in a population of infants who have been recorded at the time of death or resuscitation, three of whom died of unknown causes, we believe that bradycardia may be an important mechanism of death in infants and should be studied in various infant age categories of in order to establish normative data. One of the infants who was recorded at the time of death was 13 months of age. In the present study of 12-18 month old normal infants, no bradycardia (650BPM for 2 5 seconds) occurred during the 12 hour recordings. Further studies will be needed to determine if any significant physiologic changes (such as oxyhemoglobin desaturation)occur during the slightly longer sleep apneas found in this older age category of infants. In conclusion, healthy, full-term infants between the ages of 12 and 18 months frequently experience relatively short sleep apnea (6 to 13 seconds), but rarely longer than 16 seconds. Percent periodic breathing in this population is similar to that in 5-12 month old infants. Bradycardia, as defined earlier, was not found in these healthy infants. Normative mean heart rate and respiratory rate by I2 hour recordings were determined.
RESULTS
REFERENCES
111.4
Tt_
11.1
32.3
Tt_
4.9
t 0.4
330.4
TABLE 2-Data on Apnea and Periodic Breathing (PB) in 88 Normal Infants. 12-18 Months of Age ~
~
Mean
Median
Range
* 0.41
0.49
5
3.88
10.55
0-1.6 0-17.0
0.29 0.46
Tt_
0.50 0.54
0.00 0.25
0-2.5 0-2.4
0.38
f 0.61
0.00
(L2.9
0.36
* 0.39
0.23
0-1 .4
~~
Apnea density Longest apnea (seconds) Percent PB Longest episode of PB (minutes) Episodes of PB/100 min of quiet time Average duration of PB episodes (minutes)
SD
0.50 9.60
?
All parameters of heart rate and respiratory rate were analyzed for the entire group of 88 12.0-18.0 month old subjects, for the two age-subsets, and for males vs. females. The mean and median values were not different between age subgroups and between sexes. Therefore, the values for all infants in this study were combined for the final results (Table 2). Nineteen apneic spells > I 2 seconds (in 21.6% of infants) were recorded, one lasting 16.2 and two 17 seconds. Taking the longest apneic episode from each sub-
Steinschneider A. Prolonged apnea and the sudden infant death syndrome: Clinical and laboratory observations. Pediatrics. 1972; 60:64&653. Oren J , Kelly D, Shannon DC. Identification of a high risk group for SIDS among infants who were resuscitated for sleep apnea. Pediatrics. 1986; 77:495499. Deykin E, Bauman ML, Kelly DH, HsiehCC, Shannon D. Apnea of infancy and subsequent neurologic, cognitive, and behavioral status. Pediatrics. 1984; 73:638445. Kelly DH, Golub H, Carley D, Shannon DC. Pneumograrns in infants who subsequently died of SIDS. J Pediatr. 1986; 109:249259.
Apnea and Periodic Breathing 5. Kelly DH, Pathak A, Meny R. Sudden severe bradycardia in infancy. Pediatr Pulmonol. 1991; l0:199-204. 6. Kelly DH. Home Monitoring. In: Beckman RC, Brouillette RT, Hunt CF, eds. Respiratory Control Disorders in Infants and Children. Baltimore: Williams & Wilkins, In Press. 7. Kelly DH, Stellwagon LM, Kaitz E, Shannon DC. Apnea and periodic breathing in normal full-term infants during the first twelve months. Pediatr Pulrnonol. 1985; 1:215-219.
171
8. Hunt CE, Brouillctte RT, Hanson D, David RJ, Stein IM, Weissbluth M. Home pneumograms in normal infants. J Pediatr. 1985; 10655 I . 9. Stein IM, White A. kennedy JL, Merisalo RL, Chernoff H, Gould JB. Apnea recordings of healthy infants at 40,44, and 52 weeks postconception. Pediatrics. 1979; 63:724-730. 10. Kelly DH, Golub H, Shannon DC. Computer analysis of pneumograms. Am Rev Respir Dis. 1984; 129: 208.
