ARTICULO DE LA IMPPORTANCIA DE ECO

1. Journal of Perinatology (2007) 27, 291–296
r 2007 Nature Publishing Group All rights reserved. 0743-8346/07 $30
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ORIGINAL ARTICLE
Diagnosis of patent ductus arteriosus by a neonatologist
with a compact, portable ultrasound machine
HC Lee1, N Silverman2 and SR Hintz3
1
Department of Pediatrics, Division of Neonatal and Developmental Medicine, Stanford University, Palo Alto, CA, USA; 2Department
of Pediatrics, Division of Pediatric Cardiology, Stanford University, Palo Alto, CA, USA and 3Department of Pediatrics, Division
of Neonatal and Developmental Medicine, Stanford University, Palo Alto, CA, USA
hemorrhage, bronchopulmonary dysplasia and pulmonary
Objectives: To conduct a pilot study assessing a neonatologist’s accuracy hemorrhage.1–5 In a review of periventricular leukomalacia in
in diagnosing patent ductus arteriosus (PDA) using compact, portable preterm infants, PDA was associated with decreased cerebellar
ultrasound after limited training. volume, area of the vermis and diameter of the pons.6 The
Study design: Prospective study of premature infants scheduled for frequency of PDA is high in premature infants, ranging from
echocardiography for suspected PDA. A neonatologist with limited training 53% in infants born before 34-weeks gestation, up to 65% in
performed study exams before scheduled exams. Sensitivity and specificity infants born before 26-weeks gestation.7,8 PDA in preterm
were calculated, compared to the scheduled echocardiogram interpreted infants often requires pharmacologic or surgical closure.
by a cardiologist. Treatment of PDA has been shown to improve pulmonary function,
including increase in dynamic compliance, tidal volume and
Results: There were 24 exams. Compared to the scheduled exam, the
minute ventilation.9 Early pharmacological treatment has also
neonatologist’s exam had sensitivity 69% (95% confidence interval (CI),
been shown to reverse low renal and splanchnic blood flow in
41 to 89%) and specificity 88% (95% CI, 47 to 99%). When a cardiologist
infants with PDA.10
interpreted the study exams, the sensitivity was 87% (95% CI, 60 to 98%)
Although there are clinical signs for diagnosis of PDA including
and specificity 71% (95% CI, 29 to 96%).
auscultation of a cardiac murmur, bounding pulses and wide pulse
Conclusion: A neonatologist with limited training was able to detect PDA pressure, studies have shown that physical exam is inadequate in
with moderate success. A more rigorous training process or real-time detecting significant PDAs in preterm infants.11–13 The current
transmission with cardiologist interpretation may substantially improve standard of care for diagnosis of PDA is an echocardiogram, yet
accuracy. Institutions with experienced technicians and on-site pediatric echocardiography is not routinely taught to neonatologists.
cardiologists may not gain from intensive training of neonatologists, but Nevertheless, it has been suggested that patient care could be
hospitals where diagnosis and treatment of PDA would be delayed may improved in the neonatal intensive care unit (NICU) if
benefit from such processes. neonatologists were trained in echocardiography.14
Journal of Perinatology (2007) 27, 291–296. doi:10.1038/sj.jp.7211693; Advances in technology are allowing echocardiography to be
published online 15 March 2007 performed by nontraditional personnel in certain settings.
Ultrasound technology has become more compact, allowing use as
Keywords: patent ductus arteriosus; echocardiography; neonatologist;
diagnosis a point-of-care diagnostic tool. A handheld ultrasound was found
to be effective in the diagnosis of congenital heart disease,
including PDA.15 In this series, the interpreters were experienced
echocardiographers. Such devices are being utilized in settings
Introduction
such as the emergency department and surgical ICUs where a
Patent ductus arteriosus (PDA) in premature infants is an quick, focused evaluation could benefit the patient.16 Neonatal
associated factor in serious neonatal morbidities, associated units may also benefit from small handheld ultrasound devices for
with increased risk of necrotizing enterocolitis, intraventricular assessment of umbilical line placement and cerebral blood flow.
Correspondence: Dr SR Hintz, Department of Pediatrics, Division of Neonatal and We performed a pilot study to assess the potential utility of a
Developmental Medicine, Stanford University, 750 Welch Road, Suite 315, Palo Alto, limited training program to diagnose PDA for a neonatologist with
CA 94304, USA. no cardiology background. We used a portable ultrasound
E-mail: srhintz@stanford.edu
Received 5 September 2006; revised 18 December 2006; accepted 10 January 2007; published machine, one which could potentially be used in small NICUs
online 15 March 2007 without ready access to a pediatric cardiologist.

2. Diagnosis of PDA by a Neonatologist
HC Lee et al
292
Methods the treating physician decided that the patient should not be
This was a prospective, masked pilot study of the accuracy of PDA enrolled for any reason, the scheduled echocardiogram would be
diagnosis by neonatologist-performed compact ultrasound exam performed before the study exam could be completed, or if the
compared with routine echocardiography. This pilot study was trained neonatologist was unavailable to perform the study exam.
approved by the Stanford University Institutional Review Board. Informed consent was obtained for all patients who participated in
The ‘routine echocardiogram’ was the exam ordered by the the study.
medical team taking care of the patient for clinical indications. On some occasions, an infant received more than one
This exam was performed by an experienced technologist or echocardiogram to follow-up on the status of PDA. For these
pediatric cardiologist using the Acuson Sequoia (Siemens USA, infants, the study exam could be repeated for a maximum of two
Malvern, PA, USA), the primary device used by the pediatric times, before each routine echocardiogram.
cardiology service in our institution.
The ‘study exam’ was performed by a neonatologist who Procedure
underwent training in echocardiography, focusing on diagnosis of Enrolled patients underwent the study exam consisting of a
PDA; no other neonatologists were trained. This exam was compact, portable ultrasound exam (Acuson Cypress, Siemens USA)
performed with the Acuson Cypress (Siemens USA), a portable by the study neonatologist before the routine echocardiogram
ultrasound machine, approximately the size of a briefcase, with performed by pediatric cardiology. Using the information as
fewer advanced capabilities than the Sequoia, but with features outlined previously, the neonatologist made a determination of
such as Doppler and M-mode. The standard Cypress neonatal probe patent ductus if color Doppler views indicated shunting across
was used at a frequency of 7.5 MHz. The training process included the ductus. A subjective determination of ductal size was made:
instruction on the working of the ultrasound machine, application small, moderate or large. Results of the study exam were not
of the transducer to the various sites on the patient, addition of revealed to caregivers, cardiologists or families and did not
Doppler techniques, and pulsed continuous wave to denote influence treatment decisions. No clinical actions were based on
magnitude of shunting. Five factors were considered as criteria for these study results. These results were noted on a dated and timed
diagnosis of a patent ductus: (1) left atrial size assessed from the confidential study form immediately after the study exam, and sent
aortic root and the left atrial aortic root relation, (2) left to two different confidential electronic email accounts, to assure
ventricular size and function, (3) Color Doppler estimate of ductus they would not be amended. The neonatologist recorded the
size at the point of the vena contracta (the narrowest portion of the patency of the ductus, and if patent, an interpretation of the size
flow jet), (4) the velocity and character of the ductus Doppler of the ductus.
signal, and (5) the amount of retrograde abdominal flow. The The primary outcome variable to be measured was the accuracy
training included visualization of the parasternal long axis view, of the diagnosis of PDA by the neonatologist using the compact,
the parasternal short axis view to visualize pulmonary arteries, portable ultrasound machine. The routine exam performed by the
apical four-chamber view, subcostal view and suprasternal views, pediatric cardiology service was considered the gold standard for
including the ductus cut.17 Using this information, the diagnosis. In general, this exam was performed by a skilled
neonatologist made a determination of patent ductus if the color pediatric echocardiography technician or member of the pediatric
Doppler views indicated shunting across the ductus. Pulse wave cardiology staff or faculty, and subsequently interpreted by a
Doppler in the descending aorta was used to augment the pediatric cardiologist. None of these practitioners knew the results
diagnosis. A subjective determination of ductal size was made of the study exam.
(small, moderate or large) based on this information. The study exams were recorded on electronic media and later
The total training experience consisted of 2 h of lecture reviewed in a masked fashion by a cardiologist who was not
including recorded tapes, observation of eight exams by familiar with the patients in the study. This cardiologist knew
experienced technicians, and three practice exams with guidance neither the study exam interpretation by the neonatologist, nor the
on real patients. Approximately 50% of these evaluations had PDA. routine exam interpretation by the pediatric cardiologist. The study
The total training time was approximately 8 h. Midway through the cardiologist interpreted the study exams and also graded the quality
study, the study cardiologist reviewed the study exams already done of the exams in a subjective fashion. For some selected study exams
with the neonatologist for 1 h. in which there were discrepancies between the study exam results
and the routine exam, the study cardiologist also reviewed the
Subjects routine exam.
Patients in the NICU who were undergoing evaluation only for
suspected PDA, with birth weight 401 to 2000 g or <34-weeks Data analysis
gestational age were eligible for this pilot study. The period of Sensitivities and specificities with 95% confidence intervals of the
enrollment was from January to July 2005. Infants were excluded if neonatologist’s study exam compared with the routine
Journal of Perinatology

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echocardiogram were calculated. After the primary analysis, we also within six h of the cardiology exam for 20 of the studies. Two study
looked at the diagnosis of moderate or large PDAs as determined by exams occurred 9 h before (exam no. 2) and 23 h before (exam
the routine exam. no. 10) the cardiology exam. The exact timing of the cardiology
We also calculated sensitivity and specificity of the study exam for two of the studies was unable to be determined (exams
cardiologist’s interpretation of the study exam performed by the nos. 19 and 21). The study cardiologist did not routinely go over
neonatologist compared with the routine echocardiogram results, the routine exams by the pediatric cardiology service that correlated
again with the routine echocardiogram considered as the gold with the study exams. However, on one occasion, when the
standard. The study cardiologist was masked to both the cardiologist saw a PDA in the study exam for which the cardiology
neonatologist’s interpretation of the study exam, and the formal service had reported no PDA, he reviewed both studies and his
interpretation of the routine echocardiogram performed by the interpretation of both the study exam and the routine exam was
pediatric cardiology service. the presence of a small PDA (exam no. 8).
Compared to the routine echocardiogram, the study exam as
interpreted by the neonatologist had 69% sensitivity (95% CI, 44 to
Results 86%) and 88% specificity (95% CI, 53 to 98%) (Table 2). The
There were 24 exams performed on a total of 14 patients (Table 1). positive predictive value was 92%, whereas the negative predictive
All study exams were performed before the routine echocardiogram value was 58%. In the five cases where the neonatologist interpreted
performed by the cardiology service. Study exams were performed the study exam as negative when the routine cardiology evaluation
Table 1 Interpretation of study exams and routine exams
Exam no. Birth weight Gestational age Age at time Study exam Routine exam
(grams) (weeks) of study
Neo interpretation Cardiologist interpretation
PDA Y/N Size PDA Y/N Size PDA Y/N Size
1 860 30 78 h Y Small Y Tiny Y Small-moderate
2 1390 32 67 h Y Small Y Tiny Y Moderate
3 1390 32 5d Y Moderate Y Small Y Moderate
4 647 24 13 d Y Small N N
5 1197 28 7d N N Y Very small
6 1053 29 55 h Y Large Y Big Y Large
7 1053 29 101 h Y Moderate Y Moderate Y Moderate
8 820 24 7d Y Small Y 1 mm Ya Smalla
9 1146 30 5d N Y Tiny Y Tiny
10 820 24 13 d N N N
11 968 29 6d N N N
12 968 29 16 d Y Small N Y Small-moderate
13 866 25 42 h N Y Large Y Large
14 969 26 78 h Y Small Y Small Y Large
15 969 26 5d Y Small Y Small Y Small
b
16 866 25 8d N N
17 969 26 8d N Y Small N
18 740 26 11 d N N N
19 740 26 17 d N Y Tiny N
20 1125 28 5d N N N
21 1470 30 106 h N Y Large Y Moderate
22 1743 31 5d Y Moderate Y Small Y Small
23 1743 31 7d Y Small Y Tiny Y Small
b
24 1743 31 14 d N Y Tiny
Abbreviations: d, days; N, no; PDA, patent ductus arteriosus; Y, yes.
a
Exam was initially noted to be negative by routine exam cardiologist, however upon secondary review, there was noted to be a small PDA.
b
Exam was judged to be inadequate by study cardiologist.
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Table 2 Results of routine exams and study exams interpreted by Table 3 Results of routine exams and study exams interpreted by
neonatologist neonatologist, excluding small PDAs
Routine Routine Routine Routine
ECHO: PDA ECHO: no PDA ECHO: PDA ECHO: no PDA
Study exam: PDA 11 1 12 Study exam: PDA 7 1 8
Study exam: no PDA 5 7 12 Study exam: no PDA 2 7 9
16 8 24 9 8 17
Abbreviation: PDA, patent ductus arteriosus. Abbreviation: PDA, patent ductus arteriosus.
Sensitivity ¼ 11/16 ¼ 0.69; positive predictive value ¼ 0.92. Sensitivity ¼ 7/9 ¼ 0.78; positive predictive value ¼ 0.88.
Specificity ¼ 7/8 ¼ 0.88; negative predictive value ¼ 0.58. Specificity ¼ 7/8 ¼ 0.88; negative predictive value ¼ 0.78.
was positive for PDA, three of those five cases had PDAs which were Table 4 Results of routine exams and study exams interpreted by study
considered small or tiny (Table 1). cardiologist
Six PDAs were considered to be small or tiny by echocardiogram Routine Routine
performed by the cardiology service; if these exams were excluded, ECHO: PDA ECHO: no PDA
the sensitivity was 78% (45 to 94%) and specificity 88% (53 to 98%)
(Table 3). The sensitivity and specificity of the masked cardiologist Study exam: PDA 13 2 15
interpretation of the study exam compared with the routine Study exam: no PDA 2 5 7
echocardiogram were also determined (Table 4). Two of the studies 15 7 22
were deemed uninterpretable owing to poor quality. The study Abbreviation: PDA, patent ductus arteriosus.
cardiologist interpretation of the remaining 22 studies had Sensitivity ¼ 13/15 ¼ 0.87; positive predictive value ¼ 0.87.
Specificity ¼ 5/7 ¼ 0.71; negative predictive value ¼ 0.71.
sensitivity of 87% (62 to 96%) and specificity 71% (36 to 92%).
increasingly by nontraditional practitioners, such as nurses in
Discussion obstetrics, trauma surgeons and emergency physicians.20–23
In our pilot study, we found that a neonatologist with very limited By using telephone lines, real-time transmission of
training in echocardiography was able to detect PDA in preterm echocardiography can be performed. Some NICUs are taking
infants with moderate sensitivitiy and specificity using a portable, advantage of this technology, in which a cardiologist guides a
compact ultrasound device; accuracy improved further when technician to perform the study, then interprets the study from a
considering only moderate to large PDAs. A cardiologist interpreting distance.24 In that series, 182 of the 500 exams performed were for
the study exams had slightly better success than the neonatologist. suspected PDA. There may be practicing neonatologists who do
These preliminary findings in a small number of patients suggest perform echocardiography in their NICUs for the diagnosis of PDA,
that a more intensive training program, perhaps with integration particularly in situations when a cardiologist is not available.
of real-time evaluation techniques, could result in further However, we are not aware of any previous studies reporting
diagnostic improvement. Although such a program may not be training regimens, accuracy or reliability of neonatologist-
necessary in hospitals with pediatric cardiologists and technicians, performed exams using a portable bedside device.
it may be an appropriate and feasible approach for institutions There were several limitations to this study. The methodology
without this consistent on-site availability. included several factors, any or all of which may have effected the
This is the first study describing the training of a neonatologist study results: (1) the use of a smaller portable ultrasound device as
to interpret ultrasound for the diagnosis of PDA. A previous study compared to the more sophisticated machine used by the
looked at echocardiography by a neonatologist of infants suspected cardiology service, (2) the fact that only one neonatologist
to have congenital heart disease. In that study, the cardiologist performed the study exams, and (3) the training process. The
interpretation was not considered a true gold standard, and a images on the portable device were not as clear as the usual
Cohen’s kappa of 0.84 of overall agreement was reported.18 If the machine. However, it did feature the ability to perform Doppler
cardiologist interpretation had been considered the gold standard, ultrasound and the large majority of exams were considered
the sensitivity of the neonatologist’s exam would have been 75%. sufficient by the study cardiologist. We may have seen different
Technological advancements have made ultrasound devices results had more than one neonatologist performed the study
more readily available and portable. A recent study found that a exams. However, the device was available for use on a limited
handheld ultrasound device had utility in diagnosing valvular basis and it was not practical for more than one person to
regurgitation in adults.19 Ultrasounds are being performed perform the studies. It may be the case that another neonatologist
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with the same training and similar patients may have performed 3 Tortorolo L, Vento G, Matassa PG, Zecca E, Romagnoli C. Early changes
differently. of pulmonary mechanics to predict the severity of bronchopulmonary
We reviewed the two cases (nos. 13 and 21) in which the study dysplasia in ventilated preterm infants. J Matern Fetal Neonatal Med 2002;
neonatologist missed the diagnosis of a large PDA. Both study 12: 332–337.
exams by the neonatologist were technically competent with clear 4 Redline RW, Wilson-Costello D, Hack M. Placental and other perinatal risk
factors for chronic lung disease in very low birth weight infants. Pediatr Res
views of the PDA on several views, retrograde abdominal aorta flow.
2002; 52: 713–719.
The study cardiologist (and in retrospect, the study neonatologist)
5 Lin TW, Su BH, Lin HC, Hu PS, Peng CT, Tsai CH et al. Risk factors of
visualized a large PDA in both studies. We attribute the missed pulmonary hemorrhage in very-low-birth-weight infants: a two-year
diagnoses to lack of experience and confidence on the part of a retrospective study. Acta Paediatr Taiwan 2000; 41: 255–258.
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A longer training program may also have allowed for improved A et al. MRI measurements of the pons and cerebellum in children born
diagnosis of PDA. We tried to simulate a relatively short, 1–2 days preterm; associations with the severity of periventricular leukomalacia and
training program that would allow participation by a busy perinatal risk factors. Neuroradiology 2003; 45: 730–734.
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unavailable after the training program. The training involved study: outcomes to discharge from hospital for infants born at the threshold
education in learning how to use the ultrasound device itself, of viability. Pediatrics 2000; 106: 659–671.
learning the various views, and the nuances of the diagnosis of 8 Hammoud MS, Elsori HA, Hanafi EA, Shalabi AA, Fouda IA, Devarajan LV.
Incidence and risk factors associated with the patency of ductus arteriosus in
PDA in a very small infant. We found that the neonatologist had
preterm infants with respiratory distress syndrome in Kuwait. Saudi Med J
room for improvement in both the technical skills of
2003; 24: 982–985.
echocardiography as well as interpretation of exams to diagnose 9 Szymankiewicz M, Hodgman JE, Siassi B, Gadzinowski J. Mechanics
PDA. of breathing after surgical ligation of patent ductus arteriosus in
There can also be some subjectivity in the interpretation of newborns with respiratory distress syndrome. Biol Neonate 2004; 85:
echocardiograms. In our study, we reviewed one particular patient 32–36.
who had a PDA seen in the study exam by both the neonatologist 10 Shimada S, Kasai T, Hoshi A, Murata A, Chida S. Cardiocirculatory
and study cardiologist (exam no. 8). Although the practicing effects of patent ductus arteriosus in extremely low-birth-weight
cardiologist’s interpretation of the routine exam in that infants with respiratory distress syndrome. Pediatr Int 2003; 45:
circumstance had been no PDA, the study cardiologist interpreted 255–262.
the routine exam as positive for PDA. However, practically 11 Davis P, Turner-Gomes S, Cunningham K, Way C, Roberts R, Schmidt B.
speaking, most clinicians would consider that echocardiography is Precision and accuracy of clinical and radiological signs in premature
infants at risk of patent ductus arteriosus. Arch Pediatr Adolesc Med 1995;
the gold standard for diagnosis of PDA.
149: 1136–1141.
In summary, we found that, even with extremely limited
12 Urquhart DS, Nicholl RM. How good is clinical examination at detecting a
training, a neonatologist was able to detect PDA with moderate significant patent ductus arteriosus in the preterm neonate? Arch Dis Child
success. A more rigorous training process or real-time transmission 2003; 88: 85–86.
with cardiologist interpretation and guidance could improve 13 Skelton R, Evans N, Smythe J. A blinded comparison of clinical and
accuracy and thus avoid inappropriate patient treatment. echocardiographic evaluation of the preterm infant for patent ductus
arteriosus. J Paediatr Child Health 1994; 30: 406–411.
14 Skinner JR. Echocardiography on the neonatal unit: a job for the
Acknowledgments neonatologist or the cardiologist? Arch Dis Child 1998; 78:
401–402.
Siemens Medical Solutions USA provided equipment for this study. Henry Lee is
15 Li X, Mack GK, Rusk RA, Dai XN, El-Sedfy GO, Davies CH et al. Will a
the recipient of a Fellowship Grant from Discovery Labs. Neither institution
handheld ultrasound scanner be applicable for screening for heart
participated in the design of the study, training of the study staff, or analysis of the
abnormalities in newborns and children? J Am Soc Echocardiogr 2003; 16:
results.
1007–1014.
16 Duvall WL, Croft LB, Goldman ME. Can hand-carried ultrasound devices
be extended for use by the noncardiology medical community?
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