CLASSIFICATION OF ACUTE RESPIRATORY DISORDERS: RESULTS
During the one year enrollment period, there were 2805 live-born infants weighing at least 500 grams born without major anomalies in our hospital. We excluded 19 live-born infants from the study because of birth weights below 500 grams (15 infants) or congenital anomalies (four infants). Three were excluded for incomplete data. Of the study population, some 584 (21%) developed one or more respiratory signs in the first day, 90% of them within the first hour. The respiratory distress persisted beyond six hours in 474 (81%) of the symptomatic neonates and 400 (68%) were admitted to the neonatal intensive care unit. There were 19 deaths among these infants in the first five days of life, 12 in infants with RDS, giving an overall five-day mortality rate of 32/1000 for all infants with respiratory symptoms and a five-day case fatality rate of 111/1000 for the subset with RDS. Additional early neonatal deaths occurred in our inborn population over the study period: one infant with holoprosencephaly and all 15 infants with birth weights below 500 grams.
Chest radiographs were obtained but unavailable for review in 26 infants, leaving 558 (95%) of the symptomatic infants for diagnostic classification. There was a slight preponderance of male over female (55% vs. 45%, N.S.). Mean weight was 2613 grams, while mean gestation was 36 weeks. Sixty-seven percent of the infants with respiratory disturbances were African American, which is significantly higher than their proportion of the birth population (x2=24.8 p<0.001), probably reflecting the higher incidence of low birth weight among these infants. Sixty-three percent of the 558 births were by spontaneous vaginal delivery, 19% by forceps or vacuum assisted vaginal delivery and 18% by cesarean section. The most frequent presenting symptom was tachypnea (59%; see Table 2). Thirty-nine percent of all symptomatic infants were well within 12 hours. order levitra
Table 1.
Respiratory Distress Svndrome (RDS)
a. Early onset of clinical signs,
AND
b. At least one of the following:
(1) Reticulogranular pattern on chest film or
(2) Oxygenation response to surfactant (rise in a/A of at least 0.1)
Meconium Aspiration Svndrome (MAS)
a. Meconium in amniotic fluid
AND
b. Chest radiograph suggestive of aspiration
Pneumonia
a. Abnormal chest film,
AND
b. Two from the following list:
(1) Extra-pulmonary clinical signs of sepsis or
(2) Abnormal non-specific (screening) laboratory tests or
(3) Positive blood culture or
(4) Positive tracheal culture or
(5) Perinatal history indicating exposure (prolonged rupture, maternal fever, etc.)
Persistent Pulmonary Hypertension of the Newborn (PPHN)
a. At least one criterion for right-to-left shunt from the following:
(1) Hyperoxia test: PO2 rise < 20 mmHg after 10 min. in 100% Fi02 (Ref. 15, p.1012-3) or (2) Pre- to post-ductal PO2 gradient of > 15 mmHg or
(3) Echocardiogram showing ductal or foramen shunt or
(4) Cardiac catheterization showing ductal or foramen shunt
AND
b. At least one criterion for structurally normal heart from the following:
(1) Hyperventilation test: PO2 > 100 mmHg when PCO2 I to 20-30 mmHg (Ref. 16, p. 444) or
(2) Normal EKG or
(3) Echocardiogram showing normal anatomy or
(4) Cardiac catheterization showing normal anatomy
Transient Tachypnea of the Newborn (TTN)
a. Chest film suggestive of retained fluid (e.g. streakiness, fluid in fissure)
AND
b. Oxygen requirement less than 40%
AND
c. Not intubated
AND
d. Spontaneous improvement over two to five days
Note: Classification is based on textbook criteria3
Classification Using Traditional Diagnostic Categories
Overall, 235 (42%) of the symptomatic infants met minimal criteria for diagnosis using the outline presented in Table 1 for the most common disorders. There were 109 infants with RDS, 51 with transient tachypnea of newborn (TTN), 41 newborns with meconium aspiration syndrome (MAS) and 14 with bacterial pneumonia. Eleven symptomatic infants were diagnosed with less common conditions: one primary pulmonary hypertension (PPHN); five had pneumothorax or pneumomediastinum; two had pulmonary hemorrhage; two with pulmonary hypoplasia and one with cardiac failure. Nine infants had multiple diagnoses: three infants had RDS and pulmonary hypertension, four with meconium aspiration and pulmonary hypertension, two with RDS and pneumonia. trusted online pharmacy
Figure1. CLASSIFICATION OF ACUTE RESPIRATORY DISORDERS USING CONVENTIONAL CRITERIA
Our most striking finding was that more than half of the infants (323, or 58%) could not be classified using even the broad definitions for various acute respiratory disorders that we employed (Figure 1). Almost half of these infants (168) had a very transient illness. No laboratory or radiographic evaluations were done in many of these and they got better within a few hours. Another subset of these unclassified infants numbering 123 (38%) was symptomatic for longer periods of time, some for several days. Their clinical picture was typical for TTN but their normal x-ray was at odds with the textbook definition. Finally, there was a group of 32 infants who were intubated for various clinical indications such as poor blood gases, apnea, or marked retractions indicating impending ventilatory failure, but whose radiographic findings were not compatible with RDS or aspiration, and who could not be diagnosed with pneumonia. Some of them even received surfactant at the discretion of treating physicians but did not show a response. The cause of respiratory failure in these newborns is probably varied, including infants with depressed respiratory drive and a variety of non-specific causes of decreased lung compliance such as retained fetal lung fluid or aspirated amniotic fluid. canadian pharmacy viagra
Classification Using Modified Diagnostic Criteria
Inspection of the characteristics of our 323 patients who failed to meet any traditionally defined criteria showed one striking feature in common. They all had self-limited conditions, although these conditions varied in intensity and duration. Also, specific disorders such as infection and surfactant deficiency were ruled out by clinical tests. We separated these patients into two groups. The 291 with mild to moderate illness were assigned to the TTN category, where they joined the 51 textbook cases. Those with respira tory failure were assigned to a new category which we designated “transient respiratory insufficiency of the newborn” or TRIN. This term is applied to infants who were sick enough to need assisted ventilation and yet did not meet minimal diagnostic criteria for any established disease, a combination which was not uncommon in our series.
Figure 2. CLASSIFICATION OF ACUTE RESPIRATORY DISORDERS USING PROPOSED CRITERIA
Distribution of all symptomatic infants using this revised classification scheme is presented in Figure 2. After reassignment, the category of TTN is nearly seven times as large as before, totaling 342 infants, with 85% of the cases outside the “classic” definition, either because of very short duration of symptoms (49%) or clear CXR (36%). TRIN became the fourth largest diagnostic category overall for symptomatic infants and the second most common for infants with respiratory failure. suhagra
Clinical Characteristics of Different Diagnoses
Fifty-nine percent of the infants with RDS weighed less than 1500 grams, and most symptomatic infants in this weight category have RDS. While most of the infants with TTN were more than 2500 grams, 5% weighed less than 1500 grams. There also were nine newborns with TRIN in this weight category, making these two non-specific disorders the second and third most common causes of respiratory symptoms in the very low birth weight newborn (Figure 3). Above 1500 grams, TTN was the most frequent diagnosis. MAS was seen almost exclusively in larger infants. TRIN was present in 9% of cases in each 500-1499g and 1500-2499g categories; it was present in only 3% of infants above 2500 grams.
A total of 114 newborns had RDS, including the 14 infants with associated pneumonia or PPHN. Analyzing the 109 infants in whom RDS was the sole diagnosis, 65 of them were intubated. RDS infants who were never intubated were diagnosed based on early onset of disease and a reticulogranular pattern on chest film. Of the 65 RDS infants who received mechanical ventilation, 55 were given surfactant, while 10 did not because of rapid improvement with positive pressure ventilation (nine infants) or rapid death (one infant). Out of 55 surfactant treated RDS newborns, adequate arterial blood gas data (pre-and post-dose) were available in 42. Of these, only 21 (50%) had an improvement in their a/A ratio by >0.1. Thus, from the entire 114 newborns with RDS (defined broadly), 110 had a diagnostic x-ray picture, 25 had documented response to surfactant, and 21 had both. This last group, comprising less than one-fourth of the broadly defined group could be considered classic RDS. Thirteen percent of all respiratory disorder infants continued to be symptomatic for five or more days. In contrast, 46% of the infants meeting diagnostic criteria for RDS remained symptomatic for at least five days (x2=27.2, p<0.001).
Figure 3. WEIGHT DISTRIBUTION OF SELECTED DISEASE CATEGORIES
A total of 45 infants had meconium aspiration syndrome; out of these, four also met diagnostic criteria for persistent pulmonary hypertension of newborn. Thus, a total of 41 infants had uncomplicated MAS based on meconium-stained fluid and a chest radiograph suggestive of aspiration. Only six (15%) required mechanical ventilation. By contrast, all four infants with MAS and PPHN required ventilator support.
There were 16 infants with pneumonia. In 14 neonates it was the sole diagnosis. Nine of these had positive cultures or GBS latex antigen while the remaining five had two or more supportive criteria (rupture of membranes greater than 18 hours, abnormal white counts). Two infants had radiographs consistent with RDS and blood cultures positive for GBS. silagra uk
Table 2. FREQUENCY OF PRESENTING SIGNS IN 558 INFANTS WITH RESPIRATORY DISORDERS IN THE FIRST DAY OF LIFE
| Clinical Sign | Number of Patients | Percent of Total |
| Tachypnea | 329 | 59% |
| Retractions | 254 | 46% |
| Grunting | 152 | 27% |
| Flaring | 65 | 12% |
The 32 infants in the new category—TRIN— did not fit into any textbook category such as RDS, MAS, PPHN, or pneumonia. They either did not require any surfactant because of very rapid improvement or did not respond to it. Their radiographic pattern was either normal or non-specific (i.e., increased perihilar markings) and their condition improved steadily over hours to days. Mean birth weight for this group was 2003 grams and mean gestation was 34 weeks. Mean Apgar scores were 5 and 7 at 1 and 5 minutes, respectively.
