Pediatric Pulmonology 14:214-221 (1992)
Lung Function in &20 Month Old Infants Born Very Preterm but Without Respiratory Troubles B. Yuksel, YD,
DCH,
and A. Greenough, MD,
FRCP, DCH
Summary. Lung function results of 21 healthy infants born very prematurely are reported. The median gestational age was 29 weeks, but none had developed respiratory distress or required any form of respiratory support in the neonatal period. Lung function was assessed by measurements of thoracic gas volume (TGV) and airway resistance (Raw) plethysmographically, and of functional residualcapacity (FRC)using a helium gas dilution technique. Two separate measurements were made between 6 and 20 months of age; all infants were measured once in the first and once in the second year of life. Regression equations were calculated for TGV. Raw, and FRC related to weight, height, and postnatal age. These data provide a new set of values for very preterm infants, in part small for gestational age, without neonatal respiratory trouble. Pedlatr Q 1992 Wiiey-Liss. Inc. Pulmonol. 1992; 14:21&221. Key words: Plethysmographic; TGV and Raw; helium/dilation FRC; measurements in year 1 and 2.
INTRODUCTION
an early antenatal ultrasound examination. None of the infants had developed any signs of respiratory distress in The survival of preterm infants, even those born after the neonatal period, nor had they required any form of very short gestation, has increased significantly over the respiratory support. Measurements were made first at a last decade. Unfortunately, lung function measurements made on such infants at follow-up suggest that many of median of 9 months (range, 6-1 1 months) and second at a median of 14 months (range, 12-20 months). The median them have marked lung function abnormalities. These heights and weights at the time of the first and second data, however, are difficult to interpret as there is no year measurements were 65.5 cm (range, 59-75 cm), 6.8 appropriate reference range with which to make comparkg (range, 5.1-9.7 kg) and 76 cm (range, 72-85 cm), 10 ison. Existing reference standards have been compiled kg (range, 7.3-1 1.8 kg), respectively (Table 1). Postconfrom data on healthy infants born at or infants ceptional ages (gestational age plus postnatal age) at the who, although born preterm, have had a variety of respitime of measurements are indicated in Table 1. The indiratory troubles in the neonatal period.3 * 4 Both respiratory vidual percentiles for height and weight at birth and folillness5 and level of respiratory upp port^.^ in the neonatal low-up evaluation are shown in Table 2. period have an effect on lung function at follow-up. No infant was symptomatic at the time of measureThus, lung function measurements from a mixed group of ment. Eight infants had wheezed and coughed for 2 days preterm infant^^'^ do not provide “normal data” from or less with one or two respiratory tract infections only. which a reference range should be constructed. It is thereNone have had recurrent wheezing or cough without infore essential and the aim of the present study to gather fection and no infant had suffered from bronchiolitis. Six lung function data from infants born prematurely who of the 21 infants had family history of asthma. had no neonatal respiratory troubles.
’
MATERIALS AND METHODS Patients
During a 2-year period 161 premature infants (birthweight less than 2,000 g) had serial lung function measurements in the Paediatric Respiratory Laboratory. Twenty-one of these infants (9 boys, 12 girls) with a median birthweight of 1,312 g (range, 88&1,800 g) and a median gestational age of 29 weeks (range, 27-33 weeks) were studied. Gestational age was calculated from the mother’s last menstrual period and confirmed by 0 1992 Wiley-Liss, Inc.
From the Department of Child Health, King’s College Hospital, London, United Kingdom.
Received December 10, 1991 ; (revision) accepted for publication July I , 1992. Dr. B. Yuksel is supported by the Joint Research Committee of King’s College Hospital. Address correspondence and reprint requests to Dr. A. Greenough, Department of Child Health, King’s College Hospital, Denmark Hill, London, SE59RS. UK.
30 29 33 29 29 33 29 32 33 33 29 28 32 33 29 28 29 33 32 27 29
9.0 8.5 6.2 7.6 9.2 8.0" 6.8 6.1" 6.7 5.1" 6.5 6.4 8.2 9.2 7.3 5.6" 7.4 9.7 6.8" 6.6 5.4
yr
9.8 10.9 8.8 11.7 11.0 7.8" 10.4 9.6 10.2 9.5 8.2" 8.2"
10.0
8.9 7.3"
11.8
10.5 9.9 10.3 10.4 10.5
2nd
Weight (kg)
1st yr
"< 10th percentile for weight.
II 12 13 14 15 16 17 18 19 20 21
10
GA
BW
1,800 1,300 1,380" 1,300 1,450 1,770 960" 888" 1,480" 1,300" 1,426 1,346 1,690 1,500" 978" 1,312 1,270 1,680" 1,294' 1,210 1.284
no.
1st yr 2 3 4 5 6 7 8 9
Infant 70 70 62 64 72 75 66 62 66 60 61 59 71 74 68 59 65 75 64 66 60
1st yr yr
75 84 79 79 75 85 74 72 80 83 78 72 82 74 73 74 78 75 76 74 75
2nd
Height (cm) 13.3 13.6 8.6 11.6 13.6 12.6 11.6 12.9 7.6 7.6 8.6 8.8 10.9 12.6 12.6 9.8 8.6 11.6 10.9 11.0 8.6
1st yr
11
10 9 8 6
11 6 6 6 6 9 I1 10 7 6
9
11 7 9 II II
1st yr
16.3 22.6 18.6 18.6 16.6 18.6 15.6 18.9 16.6 19.6 19.6 14.8 21.9 15.6 15.6 19.8 18.6 15.6 18.9 17.0 16.6
yr
17 14 14
14
16 14 17 13 17 15 18 17 12 20 14 13 17 16
18
14 20
2nd
Postnatal age (mos)
2nd yr
Postconcept. age (mos) 234 200 244 230 253 I 94 217 154 286 196 2 10 I54 254 225 I84 I43 264 290 158 I43 198
1st yr 315 280 360 275 325 3 10 250 240 240 275 280 275 325 285 202 290 242 296 238 237 205
2nd yr
FRC (mL) 317 210 280 240 334 342 272 250 303 220 260 213 328 270 186 192 290 330 228 297 208
1st yr
313 390 318 242 395 294 357 275 278 268
400
367 300 443 286 367 413 299 302 352 336
2nd vr
TGV (mL)
0.738 0.952 0.871 0.958 0.757 0.570 0.798 0.616 0.944 0.890 0.808 0.723 0.774 0.833 0.989 0.745 0.910 0.879 0.692 0.481 0.965
1st yr
yr
0.858 0.933 0.813 0.960 0.885 0.794 0.836 0.794 0.682 0.818 0.700 0.878 0.833 0.896 0.835 0.734 0.823 0.829 0.865 0.852 0.764
2nd
FRC:TGV
32 47 52 37 31 51 30 46 51 45 41 50 50 41 38 38 53 34 46 36 47
1st vr
30 28 38 30 26 40 30 29 36 33 35 34 34 34 32 26 26 32 32 33 35
2nd vr
Raw (cmH,O/Ls)
TABLE 1-Individual Data of Birthweight (BW), Gestational Age (GA), Weight, Height, Postconceptional and Postnatal Age, Functional Residual Capacity (FRC), Thoracic Gas Volume (TGV), and Airway Resistance (Raw) in the First and Second Year
216
Yuksel and Greenough TABLE 2-Individual Evaluations Infant no.
Weight At birth
I
90
2 3 4 5 6 7 8 9
50
10
11 12 13 14
15 16
17 18
19
20 21
Percentiles for Weight and Height at Birth and at Follow-Up
Lung Function in &20 Month Old Infants Born Very Preterm but Without Respiratory Troubles B. Yuksel, YD,
DCH,
and A. Greenough, MD,
FRCP, DCH
Summary. Lung function results of 21 healthy infants born very prematurely are reported. The median gestational age was 29 weeks, but none had developed respiratory distress or required any form of respiratory support in the neonatal period. Lung function was assessed by measurements of thoracic gas volume (TGV) and airway resistance (Raw) plethysmographically, and of functional residualcapacity (FRC)using a helium gas dilution technique. Two separate measurements were made between 6 and 20 months of age; all infants were measured once in the first and once in the second year of life. Regression equations were calculated for TGV. Raw, and FRC related to weight, height, and postnatal age. These data provide a new set of values for very preterm infants, in part small for gestational age, without neonatal respiratory trouble. Pedlatr Q 1992 Wiiey-Liss. Inc. Pulmonol. 1992; 14:21&221. Key words: Plethysmographic; TGV and Raw; helium/dilation FRC; measurements in year 1 and 2.
INTRODUCTION
an early antenatal ultrasound examination. None of the infants had developed any signs of respiratory distress in The survival of preterm infants, even those born after the neonatal period, nor had they required any form of very short gestation, has increased significantly over the respiratory support. Measurements were made first at a last decade. Unfortunately, lung function measurements made on such infants at follow-up suggest that many of median of 9 months (range, 6-1 1 months) and second at a median of 14 months (range, 12-20 months). The median them have marked lung function abnormalities. These heights and weights at the time of the first and second data, however, are difficult to interpret as there is no year measurements were 65.5 cm (range, 59-75 cm), 6.8 appropriate reference range with which to make comparkg (range, 5.1-9.7 kg) and 76 cm (range, 72-85 cm), 10 ison. Existing reference standards have been compiled kg (range, 7.3-1 1.8 kg), respectively (Table 1). Postconfrom data on healthy infants born at or infants ceptional ages (gestational age plus postnatal age) at the who, although born preterm, have had a variety of respitime of measurements are indicated in Table 1. The indiratory troubles in the neonatal period.3 * 4 Both respiratory vidual percentiles for height and weight at birth and folillness5 and level of respiratory upp port^.^ in the neonatal low-up evaluation are shown in Table 2. period have an effect on lung function at follow-up. No infant was symptomatic at the time of measureThus, lung function measurements from a mixed group of ment. Eight infants had wheezed and coughed for 2 days preterm infant^^'^ do not provide “normal data” from or less with one or two respiratory tract infections only. which a reference range should be constructed. It is thereNone have had recurrent wheezing or cough without infore essential and the aim of the present study to gather fection and no infant had suffered from bronchiolitis. Six lung function data from infants born prematurely who of the 21 infants had family history of asthma. had no neonatal respiratory troubles.
’
MATERIALS AND METHODS Patients
During a 2-year period 161 premature infants (birthweight less than 2,000 g) had serial lung function measurements in the Paediatric Respiratory Laboratory. Twenty-one of these infants (9 boys, 12 girls) with a median birthweight of 1,312 g (range, 88&1,800 g) and a median gestational age of 29 weeks (range, 27-33 weeks) were studied. Gestational age was calculated from the mother’s last menstrual period and confirmed by 0 1992 Wiley-Liss, Inc.
From the Department of Child Health, King’s College Hospital, London, United Kingdom.
Received December 10, 1991 ; (revision) accepted for publication July I , 1992. Dr. B. Yuksel is supported by the Joint Research Committee of King’s College Hospital. Address correspondence and reprint requests to Dr. A. Greenough, Department of Child Health, King’s College Hospital, Denmark Hill, London, SE59RS. UK.
30 29 33 29 29 33 29 32 33 33 29 28 32 33 29 28 29 33 32 27 29
9.0 8.5 6.2 7.6 9.2 8.0" 6.8 6.1" 6.7 5.1" 6.5 6.4 8.2 9.2 7.3 5.6" 7.4 9.7 6.8" 6.6 5.4
yr
9.8 10.9 8.8 11.7 11.0 7.8" 10.4 9.6 10.2 9.5 8.2" 8.2"
10.0
8.9 7.3"
11.8
10.5 9.9 10.3 10.4 10.5
2nd
Weight (kg)
1st yr
"< 10th percentile for weight.
II 12 13 14 15 16 17 18 19 20 21
10
GA
BW
1,800 1,300 1,380" 1,300 1,450 1,770 960" 888" 1,480" 1,300" 1,426 1,346 1,690 1,500" 978" 1,312 1,270 1,680" 1,294' 1,210 1.284
no.
1st yr 2 3 4 5 6 7 8 9
Infant 70 70 62 64 72 75 66 62 66 60 61 59 71 74 68 59 65 75 64 66 60
1st yr yr
75 84 79 79 75 85 74 72 80 83 78 72 82 74 73 74 78 75 76 74 75
2nd
Height (cm) 13.3 13.6 8.6 11.6 13.6 12.6 11.6 12.9 7.6 7.6 8.6 8.8 10.9 12.6 12.6 9.8 8.6 11.6 10.9 11.0 8.6
1st yr
11
10 9 8 6
11 6 6 6 6 9 I1 10 7 6
9
11 7 9 II II
1st yr
16.3 22.6 18.6 18.6 16.6 18.6 15.6 18.9 16.6 19.6 19.6 14.8 21.9 15.6 15.6 19.8 18.6 15.6 18.9 17.0 16.6
yr
17 14 14
14
16 14 17 13 17 15 18 17 12 20 14 13 17 16
18
14 20
2nd
Postnatal age (mos)
2nd yr
Postconcept. age (mos) 234 200 244 230 253 I 94 217 154 286 196 2 10 I54 254 225 I84 I43 264 290 158 I43 198
1st yr 315 280 360 275 325 3 10 250 240 240 275 280 275 325 285 202 290 242 296 238 237 205
2nd yr
FRC (mL) 317 210 280 240 334 342 272 250 303 220 260 213 328 270 186 192 290 330 228 297 208
1st yr
313 390 318 242 395 294 357 275 278 268
400
367 300 443 286 367 413 299 302 352 336
2nd vr
TGV (mL)
0.738 0.952 0.871 0.958 0.757 0.570 0.798 0.616 0.944 0.890 0.808 0.723 0.774 0.833 0.989 0.745 0.910 0.879 0.692 0.481 0.965
1st yr
yr
0.858 0.933 0.813 0.960 0.885 0.794 0.836 0.794 0.682 0.818 0.700 0.878 0.833 0.896 0.835 0.734 0.823 0.829 0.865 0.852 0.764
2nd
FRC:TGV
32 47 52 37 31 51 30 46 51 45 41 50 50 41 38 38 53 34 46 36 47
1st vr
30 28 38 30 26 40 30 29 36 33 35 34 34 34 32 26 26 32 32 33 35
2nd vr
Raw (cmH,O/Ls)
TABLE 1-Individual Data of Birthweight (BW), Gestational Age (GA), Weight, Height, Postconceptional and Postnatal Age, Functional Residual Capacity (FRC), Thoracic Gas Volume (TGV), and Airway Resistance (Raw) in the First and Second Year
216
Yuksel and Greenough TABLE 2-Individual Evaluations Infant no.
Weight At birth
I
90
2 3 4 5 6 7 8 9
50
10
11 12 13 14
15 16
17 18
19
20 21
Percentiles for Weight and Height at Birth and at Follow-Up
