- Email: [email protected]
Effectiveness of neonatal transport
6 82
Editorial correspondence
oped a patent ductus arteriosus (PDA) also received greater fluid loads than did those who did not develop a PDA. The selection of the non-PDA comparison group, however, is not clear. Table 11 suggests 46 patients with RDS and no PDA. We are given fluid data for only 18 of these patients whose RDS is termed "uncomplicated" without defining the term. Expansion on the meaning of "uncomplicated" would help in understanding why the rest of the data were discarded. We are also not given the duration of oxygen exposure in the babies without BPD. If there were no significant difference in duration of oxygen exposure between BPD and non-BPD babies, or if BPD babies had significantly less oxygen exposure, the argument implicating fluid load as a causative factor is strengthened. If BPD babies had significantly greater oxygen exposure, the association of fluid load with BPD is still valid. Frank Accurso, M.D. Pediatric pulmonaryfellow University of Colorado Medical Center Container 220 4300 E. 9th St. Denver, CO 80262
The Journal of Pediatrics April 1979
Table. Infants with congestive heart failure (13)-fluid intake ( m l / k g / d a y )
BPD (6) N o BPD (7)
Respirator
No respirator
150 _+ 11 107 + 0.5 (4)
130 _+ 16 (3)
-
BPD *- Bmnchopulmonary dysplasia. We suggest that the increased fluid load in infants with RDS who have PDA may precipitate CHF and result in prolonged respirator treatment. Whether the increased fluid intake and resultant pulmonary edema is directly related to the development of BPD, or is indirectly related, acting via increased oxygen and respirator exposure, awaits further investigation. Elizabeth R. Brown, M.D. Boston Hospitalfor Women Boston, MA
Effectiveness of neonatal transport
REFERENCE
i.
Brown ER, Stark A, Sosenko I, Lawson EE, and Avery ME: Bronchopulmonary dysplasia: Possible relationship to pulmonary edema, J PEDI^Ta 92:983, 1978.
R ty To the Editor: Dr. Accurso has raised several important questions. 1. The fluid intake given was determined by the individual physician caring for the infant. The variation in intake was not related to administration of blood, plasma, or other plasma expanders, since the same numbers of infants in all groups received these and they seldom represented more than 5 to 10% of the fluid intake. The variation was in intravenous fluids and was often related to attempts to achieve a high caloric intake early in the infant's course. 2. Uncomplicated RDS was defined in infants who had clinical and x-ray criteria for RDS but who did not develop other complications such as PDA, necrotizing enberocolitis, or sepsis. This group was included mainly for interest. The main comparison group included those infants who had both RDS and PDA but who did not develop heart failure (CHF). 3. The infants without BPD were exposed to the same levels of FIo2 as the babies with BPD; however, the duration was longer in the infants with BPD. This latter finding would be expected since the presence of BPD implies prolonged oxygen dependence. More important, we feel, is that all the infants with BPD were treated with positive pressure ventilation, whereas only one half of the infants with PDA and CHF who received a lower fluid intake required a respirator. When an infant is receiving warmed humidified air, the insensible loss should be decreased and, therefore, a lower fluid intake should be required. The Table may clarify this point.
To the Editor: Chance et ail provide ample data to support their conclusions that the institution of a trained neonatal transport team with specialized equipment significantly reduces the mortafity rate and length of hospital stay for transported neonates weighing less than 1,500 gm. However, the conclusions that transport of infants weighing less than 1,500 gm, ex utero, should be regarded only as an interim measure and that there is no doubt that the uterus remains the safest of all transport incubators, are not supported by the data presented. The data deal only with transported neonates and not with inborn neonates of maternal transports. Their conclusions were based on studies by Mereustein et al? in which the antenatal and neonatal transports were not similar for birth weights and gestational ages. If maternal transport is (and it may well be) the safest method of transport for neonates less than 1,500 gm, then maintaining an Neonatal Intensive Care Unit (NICU) in a children's hospital is not appropriate. Such a service should be located where mothers at risk for having newborn infants weighing less than 1,500 gm are delivering. Unpublished data from our institution indicate that acute maternal transport may not be better in terms of neonatal mortality and length of hospital stay than neonatal transport in an urban area such as southern Los Angeles County where transport is usually within 20 miles. At Long Beach Memorial Hospital, we have an active, welltrained community outreach program which regularly conducts classes and follow-up meetings at the community hospitals which refer the majority of our perinatal transports. These classes deal with recognizing problems that may require transport, stabilizing the neonate prior to transport, and the importance of keeping him warm. Follow-up mortality and morbidity meetings are held monthly, and are used to keep the referring hospitals informed about the condition of referred mothers and/or neonates, and also to provide feedback.
Volume 94 Number 4
Editorial correspondence
Table I. Inborn vs neonatal transports admitted to the N I C U 1976-1977 weighing _ 1,500 gln
Inborn
501-750 751-1,000 1,001-1,250 1,251-1,500 Totals
I
Transport
13 27 34 44
11 11 7 6
85 41 21 14
18 33 44 41
15 11 13 8
83 33 30 20
118
35
30
136
47
35
The second half of our approach to neonatal transport is the transport team, which consists of a neonatal fellow or resident, NICU nurse and, if needed, a respiratory therapist. A team is available 24 hours a day, and all neonatal transports are accomplished by this team. During 1976 and 1977 a total of 681 neonatal transports were received from more than 50 hospitals. Table I shows the mortality rates by birth weights for the 118 inborn and 136 transported neonates weighing less than 1,500 gin. The overall mortality rates for inborn neonates, when compared with those for ~ansported infants, are not significantly different when compared by chi square for either neonates weighing less than 1,000 gm or less than 1,500 gin. We feel that this lack of difference demonstrates the quality of care provided by our local community hospitals as a result of an active education program and the advantages of having a well-trained professional neonatal transport team. Before any solid recommendations can be made regarding the advantages of antenatal transport, a matched-control study seems to be warranted.
Houchang D. Modanlou, M.D. Director, Newborn Division Associate Professor of Pediatrics, UCI Miller Children's Hospital Long Beach, CA 90801 Wendy L. Dorchester Research Associate Children's & Women's Hospitals Memorial Hospital Medical Center Long Beach, CA 90801 REFERENCES 1. Chance GW, Matthew JD, Gash J, Williams (3, and CunninghamK: Neonatal transport. A controlled study of skilled assistance, J P~DImat 93:662, 1978. 2. Merenstcin GB, Pettet G, Woodall J, and Hill JM: An analysis of air transport results in the sick newborn: II. Antenatal and neonatal referrals, Am J Obstet Gynecol 128:520, 1977.
683
Are skilled manpower resources necessary for neonatal transport? Probability sampling was appropriately utilized to obtain the study (assist) type I and control type I groups. The outcome measures of physiologic measurements, mortality, and average length of stay are key issues with which we are all concerned. However, I would like answers concerning the homogeneity of the sample study population and the statistical methods. 1. Was the incidence of small for gestatlonal age (SGA) neonates different in the study and control groups? Since there was no variance ratio difference between the control and study weights, this is unlikely but the authors could answer this more directly. SGA neonates would normally have a better survival than appropriate for gestational age (AGA) neonates < 1,500 gm. A recent study I of transported neonates _< 1,000 g (1~ = 228) completed by the Infant Transport Service of New York City demonstrated a 53.3% survival rate for SGA newborn infants compared to 30.7% for AGA patients (P < 0.05 by X~ testing). 2. In attempting to show a statistical difference between the means of the two independent random samples (study and 9control) from normally distributed population (<1,500 gm neonates) having the same (unknown) variance, the authors, I presume, are utilizing the t test with a pooled estimate of the variance. However, when applying this statistic to the fisted continuous data of Tables III and V, no siotmificant difference between the study and control was noted for the pH, the incubators, Flo2 or the average length of stay in the NICU (Table V) while blood pressure difference (Table III) only reached a sit,nificant level of 0.02 < P < 0.05. 3. More important are the discrete data of mortality listed in Table IV. By X2 testing with Yates correction or by the exact X~ test, no significant difference in mortality could be detected. I would appreciate an explanation of this since I sincerely believe in the hypothesis that skilled personnel would impact favorably on outcome measures. ~ These possible statistical inaccuracies do not support this hypothesis, especially in terms of mortality.
Angelo Ferrara, M.D., Ph.D. Associate Professor Pediatrics Medical Director Infant Transport Service New York, NY 10016 REFERENCES 1 . Chance GW, Matthew JD, Gash J, Williams G, and Cunningham K" Neonatal transport. A controlled study of skilled assistance, J I~DI^TR 93:662, 1978. 2. D'Sylva Y, and Ferrara A: Transporting sick neonates 1000 grams in New York City. Correlates of survival, Pediatr Res (abstract) 12:522, 1978.
Reply To the Editor:
To the Editor: This correspondence discusses Chance et al's article: I congratulate the authors on a fine example of applying a well thoughtout experimental design to help solve a health service question:
We accept Dr. Modanlou and Dr. Dorchester's criticism that we were exceeding the bounds of our data in asserting that ex utero transport is less desirable than that in utero. We were concerned that the apparently good results obtained in our study
Editorial correspondence
oped a patent ductus arteriosus (PDA) also received greater fluid loads than did those who did not develop a PDA. The selection of the non-PDA comparison group, however, is not clear. Table 11 suggests 46 patients with RDS and no PDA. We are given fluid data for only 18 of these patients whose RDS is termed "uncomplicated" without defining the term. Expansion on the meaning of "uncomplicated" would help in understanding why the rest of the data were discarded. We are also not given the duration of oxygen exposure in the babies without BPD. If there were no significant difference in duration of oxygen exposure between BPD and non-BPD babies, or if BPD babies had significantly less oxygen exposure, the argument implicating fluid load as a causative factor is strengthened. If BPD babies had significantly greater oxygen exposure, the association of fluid load with BPD is still valid. Frank Accurso, M.D. Pediatric pulmonaryfellow University of Colorado Medical Center Container 220 4300 E. 9th St. Denver, CO 80262
The Journal of Pediatrics April 1979
Table. Infants with congestive heart failure (13)-fluid intake ( m l / k g / d a y )
BPD (6) N o BPD (7)
Respirator
No respirator
150 _+ 11 107 + 0.5 (4)
130 _+ 16 (3)
-
BPD *- Bmnchopulmonary dysplasia. We suggest that the increased fluid load in infants with RDS who have PDA may precipitate CHF and result in prolonged respirator treatment. Whether the increased fluid intake and resultant pulmonary edema is directly related to the development of BPD, or is indirectly related, acting via increased oxygen and respirator exposure, awaits further investigation. Elizabeth R. Brown, M.D. Boston Hospitalfor Women Boston, MA
Effectiveness of neonatal transport
REFERENCE
i.
Brown ER, Stark A, Sosenko I, Lawson EE, and Avery ME: Bronchopulmonary dysplasia: Possible relationship to pulmonary edema, J PEDI^Ta 92:983, 1978.
R ty To the Editor: Dr. Accurso has raised several important questions. 1. The fluid intake given was determined by the individual physician caring for the infant. The variation in intake was not related to administration of blood, plasma, or other plasma expanders, since the same numbers of infants in all groups received these and they seldom represented more than 5 to 10% of the fluid intake. The variation was in intravenous fluids and was often related to attempts to achieve a high caloric intake early in the infant's course. 2. Uncomplicated RDS was defined in infants who had clinical and x-ray criteria for RDS but who did not develop other complications such as PDA, necrotizing enberocolitis, or sepsis. This group was included mainly for interest. The main comparison group included those infants who had both RDS and PDA but who did not develop heart failure (CHF). 3. The infants without BPD were exposed to the same levels of FIo2 as the babies with BPD; however, the duration was longer in the infants with BPD. This latter finding would be expected since the presence of BPD implies prolonged oxygen dependence. More important, we feel, is that all the infants with BPD were treated with positive pressure ventilation, whereas only one half of the infants with PDA and CHF who received a lower fluid intake required a respirator. When an infant is receiving warmed humidified air, the insensible loss should be decreased and, therefore, a lower fluid intake should be required. The Table may clarify this point.
To the Editor: Chance et ail provide ample data to support their conclusions that the institution of a trained neonatal transport team with specialized equipment significantly reduces the mortafity rate and length of hospital stay for transported neonates weighing less than 1,500 gm. However, the conclusions that transport of infants weighing less than 1,500 gm, ex utero, should be regarded only as an interim measure and that there is no doubt that the uterus remains the safest of all transport incubators, are not supported by the data presented. The data deal only with transported neonates and not with inborn neonates of maternal transports. Their conclusions were based on studies by Mereustein et al? in which the antenatal and neonatal transports were not similar for birth weights and gestational ages. If maternal transport is (and it may well be) the safest method of transport for neonates less than 1,500 gm, then maintaining an Neonatal Intensive Care Unit (NICU) in a children's hospital is not appropriate. Such a service should be located where mothers at risk for having newborn infants weighing less than 1,500 gm are delivering. Unpublished data from our institution indicate that acute maternal transport may not be better in terms of neonatal mortality and length of hospital stay than neonatal transport in an urban area such as southern Los Angeles County where transport is usually within 20 miles. At Long Beach Memorial Hospital, we have an active, welltrained community outreach program which regularly conducts classes and follow-up meetings at the community hospitals which refer the majority of our perinatal transports. These classes deal with recognizing problems that may require transport, stabilizing the neonate prior to transport, and the importance of keeping him warm. Follow-up mortality and morbidity meetings are held monthly, and are used to keep the referring hospitals informed about the condition of referred mothers and/or neonates, and also to provide feedback.
Volume 94 Number 4
Editorial correspondence
Table I. Inborn vs neonatal transports admitted to the N I C U 1976-1977 weighing _ 1,500 gln
Inborn
501-750 751-1,000 1,001-1,250 1,251-1,500 Totals
I
Transport
13 27 34 44
11 11 7 6
85 41 21 14
18 33 44 41
15 11 13 8
83 33 30 20
118
35
30
136
47
35
The second half of our approach to neonatal transport is the transport team, which consists of a neonatal fellow or resident, NICU nurse and, if needed, a respiratory therapist. A team is available 24 hours a day, and all neonatal transports are accomplished by this team. During 1976 and 1977 a total of 681 neonatal transports were received from more than 50 hospitals. Table I shows the mortality rates by birth weights for the 118 inborn and 136 transported neonates weighing less than 1,500 gin. The overall mortality rates for inborn neonates, when compared with those for ~ansported infants, are not significantly different when compared by chi square for either neonates weighing less than 1,000 gm or less than 1,500 gin. We feel that this lack of difference demonstrates the quality of care provided by our local community hospitals as a result of an active education program and the advantages of having a well-trained professional neonatal transport team. Before any solid recommendations can be made regarding the advantages of antenatal transport, a matched-control study seems to be warranted.
Houchang D. Modanlou, M.D. Director, Newborn Division Associate Professor of Pediatrics, UCI Miller Children's Hospital Long Beach, CA 90801 Wendy L. Dorchester Research Associate Children's & Women's Hospitals Memorial Hospital Medical Center Long Beach, CA 90801 REFERENCES 1. Chance GW, Matthew JD, Gash J, Williams (3, and CunninghamK: Neonatal transport. A controlled study of skilled assistance, J P~DImat 93:662, 1978. 2. Merenstcin GB, Pettet G, Woodall J, and Hill JM: An analysis of air transport results in the sick newborn: II. Antenatal and neonatal referrals, Am J Obstet Gynecol 128:520, 1977.
683
Are skilled manpower resources necessary for neonatal transport? Probability sampling was appropriately utilized to obtain the study (assist) type I and control type I groups. The outcome measures of physiologic measurements, mortality, and average length of stay are key issues with which we are all concerned. However, I would like answers concerning the homogeneity of the sample study population and the statistical methods. 1. Was the incidence of small for gestatlonal age (SGA) neonates different in the study and control groups? Since there was no variance ratio difference between the control and study weights, this is unlikely but the authors could answer this more directly. SGA neonates would normally have a better survival than appropriate for gestational age (AGA) neonates < 1,500 gm. A recent study I of transported neonates _< 1,000 g (1~ = 228) completed by the Infant Transport Service of New York City demonstrated a 53.3% survival rate for SGA newborn infants compared to 30.7% for AGA patients (P < 0.05 by X~ testing). 2. In attempting to show a statistical difference between the means of the two independent random samples (study and 9control) from normally distributed population (<1,500 gm neonates) having the same (unknown) variance, the authors, I presume, are utilizing the t test with a pooled estimate of the variance. However, when applying this statistic to the fisted continuous data of Tables III and V, no siotmificant difference between the study and control was noted for the pH, the incubators, Flo2 or the average length of stay in the NICU (Table V) while blood pressure difference (Table III) only reached a sit,nificant level of 0.02 < P < 0.05. 3. More important are the discrete data of mortality listed in Table IV. By X2 testing with Yates correction or by the exact X~ test, no significant difference in mortality could be detected. I would appreciate an explanation of this since I sincerely believe in the hypothesis that skilled personnel would impact favorably on outcome measures. ~ These possible statistical inaccuracies do not support this hypothesis, especially in terms of mortality.
Angelo Ferrara, M.D., Ph.D. Associate Professor Pediatrics Medical Director Infant Transport Service New York, NY 10016 REFERENCES 1 . Chance GW, Matthew JD, Gash J, Williams G, and Cunningham K" Neonatal transport. A controlled study of skilled assistance, J I~DI^TR 93:662, 1978. 2. D'Sylva Y, and Ferrara A: Transporting sick neonates 1000 grams in New York City. Correlates of survival, Pediatr Res (abstract) 12:522, 1978.
Reply To the Editor:
To the Editor: This correspondence discusses Chance et al's article: I congratulate the authors on a fine example of applying a well thoughtout experimental design to help solve a health service question:
We accept Dr. Modanlou and Dr. Dorchester's criticism that we were exceeding the bounds of our data in asserting that ex utero transport is less desirable than that in utero. We were concerned that the apparently good results obtained in our study