Does DeLee suction at the perineum prevent meconium aspiration syndrome? Horado s. Falciglia, MD: Colleen Henderschott, MD," Phillip Potter, MD,b and Rick Helmchen, BS' Cincinnati, Ohio OBJECTIVE: We attempted to determine the impact of "early" (before delivery of the chest) oronasopharyngeal Delee suctioning at the perineum in the prevention of meconium aspiration syndrome and to confirm that meconium aspiration syndrome is a postnatal event. STUDY DESIGN: We compared infants with meconium-stained fluid who underwent "early" oronasopharyngeal Delee suctioning with a similar group of infants whose airways were suctioned "late" (after chest delivery). Practicing obstetricians did not know the study was being conducted by the pediatric staff, and an independent observer documented whether obstetricians performed "early" or "late" oronasopharyngeal Delee suctioning. Immediate postnatal tracheal suctioning was performed in both groups. The study was conducted in a private tertiary care center averaging 5800 deliveries annually. A consecutive sample of 438 infants with meconium-stained fluid was analyzed. Of these infants, 221 received "early" oronasopharyngeal Delee suctioning, while 217 infants were suctioned "late". RESULTS: Of the 438 infants with meconium-stained fluid, meconium aspiration syndrome developed in 38 (9%). These infants had higher rates of fetal distress (Le., abnormal fetal heart rates) and lower Apgar scores (:56) than infants without meconium aspiration syndrome (58% vs 17% and 65% vs 13%, respectively; p < 0.001). Forty-five percent of the infants with meconium aspiration syndrome had renal failure during the first 20 hours of life. In spite of "early" oronasopharyngeal Delee suctioning, 53% of the infants in this group had meconium below the vocal cords and meconium aspiration syndrome developed in 7%. The time of oronasopharyngeal Delee suctioning did not affect the rate of meconium aspiration syndrome or the presence of meconium below the vocal cords. CONCLUSIONS: We concluded that "early" oronasopharyngeal Delee suctioning at the perineum does not affect the rate of meconium aspiration syndrome. We speculate that meconium aspiration syndrome is predominantly an intrauterine event associated with fetal distress and that meconium in the airways is merely a "marker" of previous fetal hypoxia. (AM J OBSTET GVNECOL 1992;167:1243-9.)
Key words: DeLee and tracheal suctioning, meconium aspiration syndrome During the last few years, the obstetric and pediatric community has entertained the notion that meconium aspiration syndrome is preventable. This belief is based on the following assumptions: (1) that meconium aspiration syndrome is primarily a postnatal event and that intrauterine meconium aspiration syndrome is rare; (2) that oronasopharyngeal DeLee suctioning of meconium before delivery of the fetal chest, described by Carson et aI., J prevents meconium from being drawn into the tracheobronchial tree during the first few
From the Department of Pediatrics," the Department of Obstetrics and Gynecology,' and the Department of Medical Research,' Good Samaritan Hospital. Presented at the annual meeting of The American Pediatric Society and The Society for Pediatric Research, Anaheim, California, May
8,1990.
Received for publication November 26, 1991; revised April 3 , 1992; accepted April 21, 1992. Reprint requests: Horacio S. Falciglia, MD, Department of Pediatrics, Good Samaritan Hospital, 375 Dixmyth Ave., Cincinnati, OH
45220-2489. 611138709
breaths; and (3) as claimed by Carson et al.,J that no deaths or severe cases of meconium aspiration syndrome have occurred since the obstetric suctioning procedure was instituted. We previously reported that the "timing" of obstetric oronasopharyngeal DeLee suctioning did not influence the presence of meconium below the vocal cords or the rate of meconium aspiration syndrome .. That study prospectively analyzed the effect of DeLee and tracheal suctioning on the rate of meconium aspiration syndrome. In a series of 755 infants with meconiumstained fluid bornduring 1983, the rate of meconium aspiration syndrome was 2%. At that time, DeLee and tracheal suctioning was practiced routinely. A comparable rate was found during a retrospective review of a similar group of742 infants born in If:J75 when DeLee and tracheal suctioning was not routine. 2 In both instances suctioning did not prevent meconium aspiration syndrome or persistent pulmonary hypertension of the newborn. To determine the impact of routine oronasophar1243
1244 Falciglia et al.
November 1992 Am J Obstet Gynecol
Table I. Reasons for "late" oronasopharyngeal DeLee suctioning Infants
(N = 217)
No.
Lack of obstetrician compliance with suction protocol Miscellaneous reasons Cord around the neck Breech presentation Midforceps delivery Precipitate delivery Shoulder dystocia Fetal distress Placenta previa Prolapsed umbilical cord
%
158
73
30
14 4 3
9
7
6
3 2
1 1
3 1 1
0.5 0.5
yngeal DeLee suctioning at the perineum in vaginal deliveries or after incision in cesarean births, we tested the following hypotheses: (1) Deep and complete suctioning of the oronasopharynx before delivery of the chest ("early" suction) will eliminate meconium from below the vocal cords; (2) the rate of meconium below the vocal cords will be higher when oronasopharyngeal DeLee suctioning is performed after chest delivery ("late" suction); (3) "early" oronasopharyngeal DeLee suctioning will reduce the rate of meconium aspiration syndrome when compared with that of "late" oronasopharyngeal DeLee suctioning; (4) if meconium aspiration syndrome develops during the first few breaths, the rate of meconium aspiration syndrome in the "early" oronasopharyngeal DeLee suctioning group will be lower than in the "late" oronasopharyngeal DeLee suctioning group. Methods
The oronasopharyngeal DeLee suctioning protocol approved by our Department of Obstetrics and Gynecology suggested that oronasopharyngeal DeLee suctioning be performed in cases of meconium-stained fluid before delivery of the thorax. All patients in this study were delivered at the Perinatal Center of the Good Samaritan Hospital (a designated level III center with 5800 births annually). The patient population covered a broad socioeconomic range and consisted of 20% "service" and 80% "private" patients. Deliveries were managed by attending or resident obstetricians. Immediate newborn care in all cases of meconium-stained fluid was given by a neonatologist or a pediatric resident experiencd with endotracheal intubation. Stillbirths and premature infants 100 beats/ min was maintained, at which time the infants were reintubated. Infants with thin and thick meconium were treated similarly. Data collected during the 6-month study included the following: (1) frequency of meconium-stained fluid; (2) the "timing" of oronasopharyngeal DeLee suctioning in relation to delivery of the thorax (whether before or after); (3) the number of endotracheal intubations performed until the trachea was cleared of meconium; (4) perinatal factors, such as the frequency of fetal distress, route of delivery, gestational age, etc.; (5) neonatal morbidity; and (6) the incidence of meconium aspiration syndrome in both the "early" and "late" oronasopharyngeal DeLee suctioning groups. Infants were categorized into "early" and "late" suction groups by an independent observer according to the technique used by the individual obstetrician delivering the baby. Table I shows the reasons for "late" oronasopharyngeal DeLee suctioning. Some obstetricians never performed "early" oronasopharyngeal DeLee suctioning and others always did. Other than the timing of suctioning, the technique of oronasopharyngeal DeLee suctioning was identical in both groups. Twenty-seven percent of the infants in the "late" oronasopharyngeal DeLee suctioning group were associated with obstetric problems (i.e., breech deliveries) that made "early" oronasopharyngeal DeLee suctioning difficult to perform. Diagnosis of meconium aspiration syndrome was made in two groups of infants: (1) those with more than scant meconium in the trachea, subsequent respiratory distress, and a chest x-ray film consistent with meconium aspiration pneumonia and (2) those without meconium in the trachea, subsequent respiratory distress, and a chest x-ray film consistent with typical "patchy" areas of opacification or pulmonary air leak.
Delee suction and meconium aspiration syndrome
Volume 167 Number 5
1245
Table II. Rate of meconium aspiration syndrome in relation to time of oronasopharyngeal DeLee suctioning "Early" suetioning
I
%
No.
221
50
196 23
89
No.
Delivered with meconium-stained fluid Postnatal tracheal suctioning Meconium aspiration syndrome
"Late" suctioning
10
I
Total
%
No.
217
50
157 15
72
7
I
%
Significance
438
100
NS
353 38
81 9
NS NS
NS, Not significant.
Table III. Comparison of rate of meconium below vocal cords and meconium aspiration syndrome in relation to time of oronasopharyngeal DeLee suctioning "Early" suctioning (n
=
221)
"Late" suctioning (n
With meconium aspiration syndrome
Meconium below cords No meconium below cords No postnatal tracheal suctioning
I
=
With meconium aspiration syndrome
%
No.
%
No.
16
7
79
36
13
36
7
3
78
36
2
II
0
0
60
28
0
No.
%
No.
117
53*
79 25
217)
I
%
6
0
*p < 0.01. Parametric statistical analysis of continuous variables used the Student two-sample t test, whereas comparisons of categoric variables used the Pearson X2 test or the Fisher exact test. The two-tailed level of significance was set at p < 0.05, except where otherwise indicated. Results
There were 2607 infants born during this study period; 438 (17%) infants had meconium-stained fluid; meconium aspiration syndrome developed in 38 (9%) of this group, and none died. Of the 438 infants with meconium-stained fluid, 221 underwent "early" oronasopharyngeal DeLee suctioning, whereas 217 infants were suctioned "late". In the "early" oronasopharyngeal DeLee suctioning group we were able to perform tracheal suctioning as planned in 89% of the infants, whereas 72% received tracheal suctioning in the "late" group. Meconium aspiration syndrome subsequently developed in 10% of the infants receiving "early" oronasopharyngeal DeLee suctioning and in 7% of the infants suctioned "late" (Table II). A comparison of the rate of meconium below the vocal cords in relation to the delivery of the chest revealed that 117 of 221 (53%) infants in the "early" oronasopharyngeal DeLee suctioning group had meconium below the vocal cords, whereas 79 of 21 7 (36%) infants in the "late" oronasopharyngeal DeLee suction-
ing group had meconium below the vocal cords. This was a statistically significant difference (p < 0.01). Among infants with meconium below the vocal cords, meconium aspiration syndrome subsequently developed in 16 (7%) of the infants with "early" oronasopharyngeal DeLee suctioning and 13 (6%) with "late" oronasopharyngeal DeLee suctioning (p > 0.05). None of the 85 infants without tracheal suctioning had meconium aspiration syndrome. Their excellent condition at birth influenced the decision not to suction. These infants were excluded from the study (Table III). As expected, infants with meconium aspiration syndrome had a higher rate of fetal distress (i.e., abnormal fetal heart rates) and lower Apgar scores (:s6) at 1 minute than infants without meconium aspiration syndrome (58% vs 17% and 65% vs 13%, respectively; p < 0.00l). When the "early" and "late" oronasopharyngeal DeLee suctioning groups of meconium aspiration syndrome infants were compared, no differences were found in the rate of fetal distress, route of delivery, number of endotracheal intubations, Apgar scores at 1 and 5 minutes, gestational age, or birth weight (Table IV). Therefore the two groups were comparable. The majority of obstetricians who did not comply with the hospital'S suggested "early" oronasopharyngeal DeLee suctioning protocol were those who usually did not attend the staff meetings of the Department of
1246
Falciglia et al.
November 1992 Am J Obstet Gynecol
Table IV. Perinatal factors in relation to time of oronasopharyngeal DeLee suctioning in infants with meconium aspiration syndrome "Early" suctioning (n = 23)
"Late" suctioning (n = 15)
65
53 46
Fetal distress rate (%) Delivery by cesarean section (%) Endotracheal intubations (No.) Apgar score :s6 at I min (%) Dubowitz gestational age (wk, mean ± 2 SD) Birth weight (gm, mean ± SD)
47
Significance
NS NS NS NS NS NS
37
59 73
60
40 ± 3 3262 ± 654
40 ± 2 3549 ± 524
NS, Not significant.
Table V. Morbidity in infants with meconium aspiration syndrome in relation to time of oronasopharyngeal DeLee suctioning "Early" -suctioning morbidity (n = 23) (No.)
Mechanical ventilation Oxygen therapy head hood >0.6 1.2 mg / dl)
Obstetrics and Gynecology where such protocols are discussed. Of the 38 infants with meconium aspiration syndrome, 3 in the "early" oronasopharyngeal DeLee suctioning group and 2 in the "late" oronasopharyngeal DeLee suctioning group required intermittent mandatory ventilation. Of the infants in the "early" oronasopharyngeal DeLee suctioning group. 70% (16/23) required oxygen therapy compared with 87% (13/15) in the "late" oronasopharyngeal DeLee suctioning group. In 35% (8/23) of the infants with meconium aspiration syndrome in the "early" oronasopharyngeal DeLee suctioning group, "tension" pneumothoraces developed requiring chest tube drainage, whereas no infants in the "late" oronasopharyngeal DeLee suctioning group had a pulmonary air leak. An unexpected finding in our study was that 45% (17/38) of the infants with meconium aspiration syndrome had severe acute renal failure with oliguria «0.5 mil kg per hour) and increased creatinine (> 1.2 mg/dl) during the first 20 hours of life. Decreased urinary output in these infants responded to the administration of normal saline solution, fluids, and furosemide (Table V). Comment
The obstetric protocol chosen by our Department of Obstetrics and Gynecology was designed to prevent meconium aspiration syndrome by recommending "early" oronasopharyngeal DeLee suctioning in all deliveries. If meconium aspiration syndrome were a postnatal
3
2
14 8 I 3 11
"Late"-suctioning morbidity (n = 15) (No.)
2
2
11
o
o 1
6
event, as suggested by Carson et al.,' infants in our study whose oronasopharynges were thoroughly suctioned before the first breath should not have had meconium below the cords at the "first" endotracheal intubation. Gage et aI.' demonstrated. in an infant kitten model, that the DeLee suction catheter was more effective than the bulb syringe; however, meconium may persist in the trachea for >20 minutes after aspiration. The presence of meconium below the cords increased the likelihood of development of symptomatic meconium aspiration syndrome. Contrary to our first hypothesis, "early" oronasopharyngeal DeLee suctioning did not eliminate the presence of meconium below the vocal cords. On comparison of the "early" and "late" oronasopharyngeal DeLee suctioning groups, a significantly higher percentage (53%, p < 0.01) of infants with meconium-stained fluid had meconium below the vocal cords in spite of "early" oronasopharyngeal DeLee suctioning, which also contradicted our second hypothesis. The 9% rate of meconium aspiration syndrome in this study is higher than the 2% rate we reported in 1975 and 1983 at this institution 2 but is similar to other reports. 6 Along with the standard diagnostic criteria, infants with meconium aspiration syndrome also included those with no meconium below the vocal cords but with respiratory distress and a typical chest x-ray film indicative of meconium aspiration syndrome. This "subclinical" form of meconium aspiration syndrome could account for the relative increase in the rate of
Delee suction and meconium aspiration syndrome
Volume 167 Number 5
1247
Table VI. Selected literature regarding suction technique and meconium aspiration syndrome No. with meconzumstained fluid
Series
Year
Gregory et aI.'
1974
88
Carson et al. I
1976
273
Davis et aLI;
1985
1420
Dooley et al. 9
1985
272
Falciglia'
1988
755
Sadovskyet aLII!
1989
40
Rossi et al. 6
1989
254
Falciglia et al. (current study)
1992
438
Meconium a.lpiration syndrome Meconium below cords (%)
Suction technique
Aspiration of upper and lower airways as soon as possible Obstetric DeLee suction before delivery of shoulder; pediatricians intubate only if meconium-stained fluid at vocal cords Combined protocols of Carson et al. and Gregory et al. Combined obstetric and pediatric suctioning Combined protocols of Carson et al. and Gregory et al.; controlled for time of suctioning in relation to delivery of chest Combined protocols of Carson et al. and Gregory et aI., along with amnioinfusion Combined protocols of Carson et al. and Gregory et aI., along with chest compression Combined obstetric and pediatric suctioning; controlled for time of suctioning in relation to delivery of chest
meconium aspiration syndrome as compared with our previous report.' Although infants were stratified according to the time of oronasopharyngeal DeLee suctioning, we could not ethically or medicolegally randomize infants to an "early" or "late" oronasopharyngeal DeLee suctioning technique. However, other than the time of oronasopharyngeal DeLee suctioning, infants in both groups were similar when several perinatal factors were compared (Table IV). An increased rate of pneumothoraces was noted in the "early" oronasopharyngeal DeLee suctioning group; however, we could not determine whether this increase was related to the time and technique of oronasopharyngeal DeLee suctioning or the thickness of the meconium. This rate of pneumothoraces in the "early" oronasopharyngeal DeLee suctioning group (35%) is identical to the rate reported by us in infants with meconium aspiration syndrome in 1988." It is possible that there was a tendency toward earlier and more aggressive suctioning by the obstetrician when the meconium-stained fluid was considered thick and particulate. Both ball-valve partial airway obstruction from meconium particles and Valsalva-induced maneuvers during vigorous suction-
57
No.
16
0.7
21
29
o Amnioin-
fusion and DeLee suction 37
53 Early DeLee suction 36 Late DeLee suction
% 20 0.4
30
37 Early DeLee suction 36 Late DeLee suction
I
2
Deaths No.
I
%
0
0
0
0
12
40
0.4
0.4
14
2
2
12
2
2
0
0
0 0
0 0
0 0
0 0
22
9
4
1.5
23
10
0
0
15
7
0
0
mg have been incriminated in the pathophysiologic characteristics of pneumothoraces in infants with meconium aspiration syndrome.' This study and our previously published reports on meconium aspiration syndrome 2 are the only prospective studies to stratify infants by the time of suctioning in relation to delivery of the thorax (Table VI). Although Gregory et al. 3 did not control for the time of oronasopharyngeal DeLee suctioning, they found meconium below the vocal cords in 57% of the infants studied. In 20% with meconium below the vocal cords, meconium aspiration syndrome developed. In our study meconium aspiration syndrome developed in 15% of the infants with meconium below the vocal cords. Carson et al. I probably underestimated the rate of meconium below the vocal cords. Only a preselected group of infants with meconium-stained fluid who had meconium at the vocal cords during laryngoscopy were intubated. The rate of meconium aspiration syndrome reported in that study is the lowest in the country. Although no one has yet confirmed their work, the report has become a landmark document concerning the de-
1248
Falciglia et al.
velopment of meconium aspiration syndrome in infants. It has been referred to extensively by attorneys attempting to prove that inadequate suctioning by the obstetrician results in the development of meconium aspiration syndrome. This report has also made it impossible for institutions to develop a prospective protocol examining "early" versus "late" oronasopharyngeal DeLee suctioning of meconium-stained fluid. Rossi et al." also confirmed that current intervention of combined DeLee and tracheal suctioning is insufficient to eliminate meconium from below the vocal cords. They reported a 37% rate of meconium below the vocal cords after "early" oronasopharyngeal DeLee suctioning was performed according to the method described by Carson et al. 1 Among their 16 infants with meconium aspiration syndrome, four died as a result of severe meconium aspiration syndrome and persistent pulmonary hypertension in spite of "early" DeLee and tracheal suctioning. The reason for the failure to prevent meconium aspiration syndrome with oronasopharyngeal DeLee suctioning may be found in animal research with kittens. Pfenninger et al.,8 using oronaso pharyngeal suctioning, were able to retrieve only 56% of the aspirated material. Dooley et al. 9 reported that meconium below the vocal cords correlated with intrapartum events. When a rising baseline fetal heart rate and decreased variability were present, a significant proportion of infants (21 %) had meconium below the vocal cords. In one case routine obstetric and pediatric suctioning did not prevent a death that occurred from meconium aspiration syndrome "in utero". Sadovsky et al. 10 demonstrated that the rate of meconium below the vocal cords was effectively reduced to 0% by the combination of amnioinfusion during labor and "early" oronasopharyngeal DeLee suctioning. Our study could not confirm that meconium aspiration syndrome develops during the first few breaths, as suggested by Carson et al. 1 Contrary to our third hypothesis, "early" oronasopharyngeal DeLee suctioning did not reduce the rate of meconium aspiration syndrome. Meconium aspiration syndrome developed in 23 of 221 (10%) infants suctioned "early" whereas meconium aspiration syndrome developed in 7% of the "late" oronasopharyngeal DeLee suctioning group. Therefore meconium aspiration syndrome does not develop during the first few breaths and is an intrauterine event. The high rates of fetal distress, low Apgar scores at 1 minute, and renal failure in our infants with meconium aspiration syndrome support the role of asphyxia in the pathophysiologic features of "in utero" meconium aspiration. Several investigators using animals have reached similar conclusions. In one study in which fetal lambs were asphyxiated by umbilical cord occlusion, respiratory efforts greatly increased in strength and duration. As a result, a large volume (> 10 ml) of amniotic fluid (with
November 1992 Am J Obstet Gynecol
or without meconium) was inhaled into the tracheobronchial tree. II Fetal hypoxia and acidosis in baboons induced intrauterine gasping respirations sufficient to cause aspiration of meconium deep inito the smaller airways.12 In another study contrast material placed in the nasopharynx of fetal lambs with cord occlusion entered the trachea and remained there until the cord occlusion was removed. 13 Fetal asphyxia causes passage of meconium, pulmonary vasoconstriction, and reduced pulmonary blood flow. In response to asphyxia and acidosis the human fetus initiates substantial respiratory efforts to open the laryngeal sphincter and consequently aspirates meconium into the trachea. II With the reduction in the outflow of pulmonary fetal liquid as a secondary effect of reduced pulmonary blood flow, the self-cleansing action of the tracheobronchial tree is degraded and aspirated meconium remains in the trachea. l < Simultaneously with pulmonary changes, asphyxia also causes hypotension and reduces the fetal glomerular filtration rate. 15 Oliguria with transient renal failure is very common in both asphyxiated neonates and infants with meconium aspiration syndrome. 2 . It; In conclusion, our findings suggest that meconium aspiration is primarily an intrauterine event, and we speculate that it develops shortly after the onset of asphyxia and passage of meconium. Gasping respiratory movements may continue to mobilize meconium beyond the trachea and major airways after delivery of the infants. Meconium aspiration is an intrauterine event; therefore timing of oronasopharyngeal DeLee suctioning did not contribute to meconium aspiration syndrome in our population or change the rate of meconium aspiration syndrome. However, oronasopharyngeal DeLee suctioning before or after delivery of the chest, combined with immediate postnatal tracheal suctioning, did ameliorate the severity of meconium aspiration syndrome at our institution because no neonatal deaths occured in our study group. We therefore support the continuation of this practice. We suggest a national collaborative effort in the prevention of meconium aspiration syndrome, in which not only oronasopharyngeal DeLee suctioning but also tracheal suctioning is further evaluated in a prospective randomized contrqlled manner. We thank the pediatric residents and the nurses of the Newborn Intensive Care Unit of Good Samaritan Hospital for their assistance in completion of this study. REFERENCES I. Carson BS, Losey RW, Bowes WA, Simmons MA. Com-
bined obstetric and pediatric approach to prevent meconium aspiration syndrome. A}'I J OBSTET GnlEcoL 1976; 126:712-5. 2. Falciglia HS. Failure to prevent meconium aspiration syndrome. Obstet Gynecol 1988;71:349-53. 3. Gregory GA, Gooding CA, Phibbs RH, Tooley WHo Meconium aspiration in infants: a prospective study . .J Pediatr 1974;85:848-52.
Volume 167 Number 5
Delee suction and meconium aspiration syndrome
4. Ballard JL, Musial MJ, Myers MG. Hazards of delivery room resuscitation during oral methods of endotracheal suctioning. Pediatr Infect Dis 1986;5: 198-200. 5. Gage JE, Taeusch HW, Treves S, et al. Suctioning of upper airway meconium in newborn infants. JAMA 1981 ;246:2590-2. 6. Rossi EM, Philipson EH, Williams TG, Kalhan Sc. Meconium aspiration syndrome: intrapartum and neonatal attributes. AMJ OB5TET GYNECOL 1989; 161: 1106-10. 7. Stahlman MT. Acute respiratory disorders in the newborn. In: Avery GB, ed. Neonatology: pathophysiology and management of the newborn. Philadelphia: JB Lippincott, 1987:443. 8. Pfenninger E, Dick W, Brecht-Krauss D, Bitler F, Hoffmann H, Bowdler I. Investigation of intrapartum clearance of the upper airway in the presence of meconium contaminated amniotic fluid using an animal model. J Perinat Med 1984;12:57-67. 9. Dooley SL, Pesavento DJ, Dipp R, Soul ML, Tamura RK, Wiringa KS. Meconium below the vocal cords at delivery: correlation with intrapartum events. AM J OBSTET GyNECOL 1985; 153:767-70. 10. Sadovsky Y, Amon E, Bade ME, Petrie RH. Prophylactic amnioinfusion during labor complicated by meconium: a
preliminary report. AM J OBSTET GYNECOL 1989; 161: 613-7. Dawes GS, Fox HE, Leduc BM, et al. Respiratory movements and rapid eye movement sleep in the fetal lamb. J Physiol 1972;220: 119-43. Block MF, Kallenberger DA, Ken ID, et al. In utero meconium aspiration by the baboon fetus. Obstet Gynecol 1981;57:37-40. Adams FH, Desilets DT, Towers B. Control of flow of the fetal lung fluid at the laryngeal outlet. Respir Physiol 1967;2:302-5. Miller FC, Sacks D, Yeh S, et al. Significance of meconium during labor. AMJ OBSTET GYNECOL 1975;122:573-80. Cunningham RJ. Acute renal failure. In: Rudolph AM, ed. Pediatrics. Norwalk, Connecticut: Appleton & Lange, 1991:1245. Garcia-Alix A, Perlman JM. Early clinical findings in infants born with meconium stained amniotic fluid. Pediatr Res 1989;25:356. Davis RO, PhilipsJB, Harris BA, Wilson ER, Huddleston JF. Fatal meconium aspiration syndrome occurring despite airway management considered appropriate. AM J OBSTET GYNECOL 1985;151:731-6.
II. 12. 13. 14. 15. 16. 17.
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1249
Key words: DeLee and tracheal suctioning, meconium aspiration syndrome During the last few years, the obstetric and pediatric community has entertained the notion that meconium aspiration syndrome is preventable. This belief is based on the following assumptions: (1) that meconium aspiration syndrome is primarily a postnatal event and that intrauterine meconium aspiration syndrome is rare; (2) that oronasopharyngeal DeLee suctioning of meconium before delivery of the fetal chest, described by Carson et aI., J prevents meconium from being drawn into the tracheobronchial tree during the first few
From the Department of Pediatrics," the Department of Obstetrics and Gynecology,' and the Department of Medical Research,' Good Samaritan Hospital. Presented at the annual meeting of The American Pediatric Society and The Society for Pediatric Research, Anaheim, California, May
8,1990.
Received for publication November 26, 1991; revised April 3 , 1992; accepted April 21, 1992. Reprint requests: Horacio S. Falciglia, MD, Department of Pediatrics, Good Samaritan Hospital, 375 Dixmyth Ave., Cincinnati, OH
45220-2489. 611138709
breaths; and (3) as claimed by Carson et al.,J that no deaths or severe cases of meconium aspiration syndrome have occurred since the obstetric suctioning procedure was instituted. We previously reported that the "timing" of obstetric oronasopharyngeal DeLee suctioning did not influence the presence of meconium below the vocal cords or the rate of meconium aspiration syndrome .. That study prospectively analyzed the effect of DeLee and tracheal suctioning on the rate of meconium aspiration syndrome. In a series of 755 infants with meconiumstained fluid bornduring 1983, the rate of meconium aspiration syndrome was 2%. At that time, DeLee and tracheal suctioning was practiced routinely. A comparable rate was found during a retrospective review of a similar group of742 infants born in If:J75 when DeLee and tracheal suctioning was not routine. 2 In both instances suctioning did not prevent meconium aspiration syndrome or persistent pulmonary hypertension of the newborn. To determine the impact of routine oronasophar1243
1244 Falciglia et al.
November 1992 Am J Obstet Gynecol
Table I. Reasons for "late" oronasopharyngeal DeLee suctioning Infants
(N = 217)
No.
Lack of obstetrician compliance with suction protocol Miscellaneous reasons Cord around the neck Breech presentation Midforceps delivery Precipitate delivery Shoulder dystocia Fetal distress Placenta previa Prolapsed umbilical cord
%
158
73
30
14 4 3
9
7
6
3 2
1 1
3 1 1
0.5 0.5
yngeal DeLee suctioning at the perineum in vaginal deliveries or after incision in cesarean births, we tested the following hypotheses: (1) Deep and complete suctioning of the oronasopharynx before delivery of the chest ("early" suction) will eliminate meconium from below the vocal cords; (2) the rate of meconium below the vocal cords will be higher when oronasopharyngeal DeLee suctioning is performed after chest delivery ("late" suction); (3) "early" oronasopharyngeal DeLee suctioning will reduce the rate of meconium aspiration syndrome when compared with that of "late" oronasopharyngeal DeLee suctioning; (4) if meconium aspiration syndrome develops during the first few breaths, the rate of meconium aspiration syndrome in the "early" oronasopharyngeal DeLee suctioning group will be lower than in the "late" oronasopharyngeal DeLee suctioning group. Methods
The oronasopharyngeal DeLee suctioning protocol approved by our Department of Obstetrics and Gynecology suggested that oronasopharyngeal DeLee suctioning be performed in cases of meconium-stained fluid before delivery of the thorax. All patients in this study were delivered at the Perinatal Center of the Good Samaritan Hospital (a designated level III center with 5800 births annually). The patient population covered a broad socioeconomic range and consisted of 20% "service" and 80% "private" patients. Deliveries were managed by attending or resident obstetricians. Immediate newborn care in all cases of meconium-stained fluid was given by a neonatologist or a pediatric resident experiencd with endotracheal intubation. Stillbirths and premature infants 100 beats/ min was maintained, at which time the infants were reintubated. Infants with thin and thick meconium were treated similarly. Data collected during the 6-month study included the following: (1) frequency of meconium-stained fluid; (2) the "timing" of oronasopharyngeal DeLee suctioning in relation to delivery of the thorax (whether before or after); (3) the number of endotracheal intubations performed until the trachea was cleared of meconium; (4) perinatal factors, such as the frequency of fetal distress, route of delivery, gestational age, etc.; (5) neonatal morbidity; and (6) the incidence of meconium aspiration syndrome in both the "early" and "late" oronasopharyngeal DeLee suctioning groups. Infants were categorized into "early" and "late" suction groups by an independent observer according to the technique used by the individual obstetrician delivering the baby. Table I shows the reasons for "late" oronasopharyngeal DeLee suctioning. Some obstetricians never performed "early" oronasopharyngeal DeLee suctioning and others always did. Other than the timing of suctioning, the technique of oronasopharyngeal DeLee suctioning was identical in both groups. Twenty-seven percent of the infants in the "late" oronasopharyngeal DeLee suctioning group were associated with obstetric problems (i.e., breech deliveries) that made "early" oronasopharyngeal DeLee suctioning difficult to perform. Diagnosis of meconium aspiration syndrome was made in two groups of infants: (1) those with more than scant meconium in the trachea, subsequent respiratory distress, and a chest x-ray film consistent with meconium aspiration pneumonia and (2) those without meconium in the trachea, subsequent respiratory distress, and a chest x-ray film consistent with typical "patchy" areas of opacification or pulmonary air leak.
Delee suction and meconium aspiration syndrome
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1245
Table II. Rate of meconium aspiration syndrome in relation to time of oronasopharyngeal DeLee suctioning "Early" suetioning
I
%
No.
221
50
196 23
89
No.
Delivered with meconium-stained fluid Postnatal tracheal suctioning Meconium aspiration syndrome
"Late" suctioning
10
I
Total
%
No.
217
50
157 15
72
7
I
%
Significance
438
100
NS
353 38
81 9
NS NS
NS, Not significant.
Table III. Comparison of rate of meconium below vocal cords and meconium aspiration syndrome in relation to time of oronasopharyngeal DeLee suctioning "Early" suctioning (n
=
221)
"Late" suctioning (n
With meconium aspiration syndrome
Meconium below cords No meconium below cords No postnatal tracheal suctioning
I
=
With meconium aspiration syndrome
%
No.
%
No.
16
7
79
36
13
36
7
3
78
36
2
II
0
0
60
28
0
No.
%
No.
117
53*
79 25
217)
I
%
6
0
*p < 0.01. Parametric statistical analysis of continuous variables used the Student two-sample t test, whereas comparisons of categoric variables used the Pearson X2 test or the Fisher exact test. The two-tailed level of significance was set at p < 0.05, except where otherwise indicated. Results
There were 2607 infants born during this study period; 438 (17%) infants had meconium-stained fluid; meconium aspiration syndrome developed in 38 (9%) of this group, and none died. Of the 438 infants with meconium-stained fluid, 221 underwent "early" oronasopharyngeal DeLee suctioning, whereas 217 infants were suctioned "late". In the "early" oronasopharyngeal DeLee suctioning group we were able to perform tracheal suctioning as planned in 89% of the infants, whereas 72% received tracheal suctioning in the "late" group. Meconium aspiration syndrome subsequently developed in 10% of the infants receiving "early" oronasopharyngeal DeLee suctioning and in 7% of the infants suctioned "late" (Table II). A comparison of the rate of meconium below the vocal cords in relation to the delivery of the chest revealed that 117 of 221 (53%) infants in the "early" oronasopharyngeal DeLee suctioning group had meconium below the vocal cords, whereas 79 of 21 7 (36%) infants in the "late" oronasopharyngeal DeLee suction-
ing group had meconium below the vocal cords. This was a statistically significant difference (p < 0.01). Among infants with meconium below the vocal cords, meconium aspiration syndrome subsequently developed in 16 (7%) of the infants with "early" oronasopharyngeal DeLee suctioning and 13 (6%) with "late" oronasopharyngeal DeLee suctioning (p > 0.05). None of the 85 infants without tracheal suctioning had meconium aspiration syndrome. Their excellent condition at birth influenced the decision not to suction. These infants were excluded from the study (Table III). As expected, infants with meconium aspiration syndrome had a higher rate of fetal distress (i.e., abnormal fetal heart rates) and lower Apgar scores (:s6) at 1 minute than infants without meconium aspiration syndrome (58% vs 17% and 65% vs 13%, respectively; p < 0.00l). When the "early" and "late" oronasopharyngeal DeLee suctioning groups of meconium aspiration syndrome infants were compared, no differences were found in the rate of fetal distress, route of delivery, number of endotracheal intubations, Apgar scores at 1 and 5 minutes, gestational age, or birth weight (Table IV). Therefore the two groups were comparable. The majority of obstetricians who did not comply with the hospital'S suggested "early" oronasopharyngeal DeLee suctioning protocol were those who usually did not attend the staff meetings of the Department of
1246
Falciglia et al.
November 1992 Am J Obstet Gynecol
Table IV. Perinatal factors in relation to time of oronasopharyngeal DeLee suctioning in infants with meconium aspiration syndrome "Early" suctioning (n = 23)
"Late" suctioning (n = 15)
65
53 46
Fetal distress rate (%) Delivery by cesarean section (%) Endotracheal intubations (No.) Apgar score :s6 at I min (%) Dubowitz gestational age (wk, mean ± 2 SD) Birth weight (gm, mean ± SD)
47
Significance
NS NS NS NS NS NS
37
59 73
60
40 ± 3 3262 ± 654
40 ± 2 3549 ± 524
NS, Not significant.
Table V. Morbidity in infants with meconium aspiration syndrome in relation to time of oronasopharyngeal DeLee suctioning "Early" -suctioning morbidity (n = 23) (No.)
Mechanical ventilation Oxygen therapy head hood >0.6 1.2 mg / dl)
Obstetrics and Gynecology where such protocols are discussed. Of the 38 infants with meconium aspiration syndrome, 3 in the "early" oronasopharyngeal DeLee suctioning group and 2 in the "late" oronasopharyngeal DeLee suctioning group required intermittent mandatory ventilation. Of the infants in the "early" oronasopharyngeal DeLee suctioning group. 70% (16/23) required oxygen therapy compared with 87% (13/15) in the "late" oronasopharyngeal DeLee suctioning group. In 35% (8/23) of the infants with meconium aspiration syndrome in the "early" oronasopharyngeal DeLee suctioning group, "tension" pneumothoraces developed requiring chest tube drainage, whereas no infants in the "late" oronasopharyngeal DeLee suctioning group had a pulmonary air leak. An unexpected finding in our study was that 45% (17/38) of the infants with meconium aspiration syndrome had severe acute renal failure with oliguria «0.5 mil kg per hour) and increased creatinine (> 1.2 mg/dl) during the first 20 hours of life. Decreased urinary output in these infants responded to the administration of normal saline solution, fluids, and furosemide (Table V). Comment
The obstetric protocol chosen by our Department of Obstetrics and Gynecology was designed to prevent meconium aspiration syndrome by recommending "early" oronasopharyngeal DeLee suctioning in all deliveries. If meconium aspiration syndrome were a postnatal
3
2
14 8 I 3 11
"Late"-suctioning morbidity (n = 15) (No.)
2
2
11
o
o 1
6
event, as suggested by Carson et al.,' infants in our study whose oronasopharynges were thoroughly suctioned before the first breath should not have had meconium below the cords at the "first" endotracheal intubation. Gage et aI.' demonstrated. in an infant kitten model, that the DeLee suction catheter was more effective than the bulb syringe; however, meconium may persist in the trachea for >20 minutes after aspiration. The presence of meconium below the cords increased the likelihood of development of symptomatic meconium aspiration syndrome. Contrary to our first hypothesis, "early" oronasopharyngeal DeLee suctioning did not eliminate the presence of meconium below the vocal cords. On comparison of the "early" and "late" oronasopharyngeal DeLee suctioning groups, a significantly higher percentage (53%, p < 0.01) of infants with meconium-stained fluid had meconium below the vocal cords in spite of "early" oronasopharyngeal DeLee suctioning, which also contradicted our second hypothesis. The 9% rate of meconium aspiration syndrome in this study is higher than the 2% rate we reported in 1975 and 1983 at this institution 2 but is similar to other reports. 6 Along with the standard diagnostic criteria, infants with meconium aspiration syndrome also included those with no meconium below the vocal cords but with respiratory distress and a typical chest x-ray film indicative of meconium aspiration syndrome. This "subclinical" form of meconium aspiration syndrome could account for the relative increase in the rate of
Delee suction and meconium aspiration syndrome
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1247
Table VI. Selected literature regarding suction technique and meconium aspiration syndrome No. with meconzumstained fluid
Series
Year
Gregory et aI.'
1974
88
Carson et al. I
1976
273
Davis et aLI;
1985
1420
Dooley et al. 9
1985
272
Falciglia'
1988
755
Sadovskyet aLII!
1989
40
Rossi et al. 6
1989
254
Falciglia et al. (current study)
1992
438
Meconium a.lpiration syndrome Meconium below cords (%)
Suction technique
Aspiration of upper and lower airways as soon as possible Obstetric DeLee suction before delivery of shoulder; pediatricians intubate only if meconium-stained fluid at vocal cords Combined protocols of Carson et al. and Gregory et al. Combined obstetric and pediatric suctioning Combined protocols of Carson et al. and Gregory et al.; controlled for time of suctioning in relation to delivery of chest Combined protocols of Carson et al. and Gregory et aI., along with amnioinfusion Combined protocols of Carson et al. and Gregory et aI., along with chest compression Combined obstetric and pediatric suctioning; controlled for time of suctioning in relation to delivery of chest
meconium aspiration syndrome as compared with our previous report.' Although infants were stratified according to the time of oronasopharyngeal DeLee suctioning, we could not ethically or medicolegally randomize infants to an "early" or "late" oronasopharyngeal DeLee suctioning technique. However, other than the time of oronasopharyngeal DeLee suctioning, infants in both groups were similar when several perinatal factors were compared (Table IV). An increased rate of pneumothoraces was noted in the "early" oronasopharyngeal DeLee suctioning group; however, we could not determine whether this increase was related to the time and technique of oronasopharyngeal DeLee suctioning or the thickness of the meconium. This rate of pneumothoraces in the "early" oronasopharyngeal DeLee suctioning group (35%) is identical to the rate reported by us in infants with meconium aspiration syndrome in 1988." It is possible that there was a tendency toward earlier and more aggressive suctioning by the obstetrician when the meconium-stained fluid was considered thick and particulate. Both ball-valve partial airway obstruction from meconium particles and Valsalva-induced maneuvers during vigorous suction-
57
No.
16
0.7
21
29
o Amnioin-
fusion and DeLee suction 37
53 Early DeLee suction 36 Late DeLee suction
% 20 0.4
30
37 Early DeLee suction 36 Late DeLee suction
I
2
Deaths No.
I
%
0
0
0
0
12
40
0.4
0.4
14
2
2
12
2
2
0
0
0 0
0 0
0 0
0 0
22
9
4
1.5
23
10
0
0
15
7
0
0
mg have been incriminated in the pathophysiologic characteristics of pneumothoraces in infants with meconium aspiration syndrome.' This study and our previously published reports on meconium aspiration syndrome 2 are the only prospective studies to stratify infants by the time of suctioning in relation to delivery of the thorax (Table VI). Although Gregory et al. 3 did not control for the time of oronasopharyngeal DeLee suctioning, they found meconium below the vocal cords in 57% of the infants studied. In 20% with meconium below the vocal cords, meconium aspiration syndrome developed. In our study meconium aspiration syndrome developed in 15% of the infants with meconium below the vocal cords. Carson et al. I probably underestimated the rate of meconium below the vocal cords. Only a preselected group of infants with meconium-stained fluid who had meconium at the vocal cords during laryngoscopy were intubated. The rate of meconium aspiration syndrome reported in that study is the lowest in the country. Although no one has yet confirmed their work, the report has become a landmark document concerning the de-
1248
Falciglia et al.
velopment of meconium aspiration syndrome in infants. It has been referred to extensively by attorneys attempting to prove that inadequate suctioning by the obstetrician results in the development of meconium aspiration syndrome. This report has also made it impossible for institutions to develop a prospective protocol examining "early" versus "late" oronasopharyngeal DeLee suctioning of meconium-stained fluid. Rossi et al." also confirmed that current intervention of combined DeLee and tracheal suctioning is insufficient to eliminate meconium from below the vocal cords. They reported a 37% rate of meconium below the vocal cords after "early" oronasopharyngeal DeLee suctioning was performed according to the method described by Carson et al. 1 Among their 16 infants with meconium aspiration syndrome, four died as a result of severe meconium aspiration syndrome and persistent pulmonary hypertension in spite of "early" DeLee and tracheal suctioning. The reason for the failure to prevent meconium aspiration syndrome with oronasopharyngeal DeLee suctioning may be found in animal research with kittens. Pfenninger et al.,8 using oronaso pharyngeal suctioning, were able to retrieve only 56% of the aspirated material. Dooley et al. 9 reported that meconium below the vocal cords correlated with intrapartum events. When a rising baseline fetal heart rate and decreased variability were present, a significant proportion of infants (21 %) had meconium below the vocal cords. In one case routine obstetric and pediatric suctioning did not prevent a death that occurred from meconium aspiration syndrome "in utero". Sadovsky et al. 10 demonstrated that the rate of meconium below the vocal cords was effectively reduced to 0% by the combination of amnioinfusion during labor and "early" oronasopharyngeal DeLee suctioning. Our study could not confirm that meconium aspiration syndrome develops during the first few breaths, as suggested by Carson et al. 1 Contrary to our third hypothesis, "early" oronasopharyngeal DeLee suctioning did not reduce the rate of meconium aspiration syndrome. Meconium aspiration syndrome developed in 23 of 221 (10%) infants suctioned "early" whereas meconium aspiration syndrome developed in 7% of the "late" oronasopharyngeal DeLee suctioning group. Therefore meconium aspiration syndrome does not develop during the first few breaths and is an intrauterine event. The high rates of fetal distress, low Apgar scores at 1 minute, and renal failure in our infants with meconium aspiration syndrome support the role of asphyxia in the pathophysiologic features of "in utero" meconium aspiration. Several investigators using animals have reached similar conclusions. In one study in which fetal lambs were asphyxiated by umbilical cord occlusion, respiratory efforts greatly increased in strength and duration. As a result, a large volume (> 10 ml) of amniotic fluid (with
November 1992 Am J Obstet Gynecol
or without meconium) was inhaled into the tracheobronchial tree. II Fetal hypoxia and acidosis in baboons induced intrauterine gasping respirations sufficient to cause aspiration of meconium deep inito the smaller airways.12 In another study contrast material placed in the nasopharynx of fetal lambs with cord occlusion entered the trachea and remained there until the cord occlusion was removed. 13 Fetal asphyxia causes passage of meconium, pulmonary vasoconstriction, and reduced pulmonary blood flow. In response to asphyxia and acidosis the human fetus initiates substantial respiratory efforts to open the laryngeal sphincter and consequently aspirates meconium into the trachea. II With the reduction in the outflow of pulmonary fetal liquid as a secondary effect of reduced pulmonary blood flow, the self-cleansing action of the tracheobronchial tree is degraded and aspirated meconium remains in the trachea. l < Simultaneously with pulmonary changes, asphyxia also causes hypotension and reduces the fetal glomerular filtration rate. 15 Oliguria with transient renal failure is very common in both asphyxiated neonates and infants with meconium aspiration syndrome. 2 . It; In conclusion, our findings suggest that meconium aspiration is primarily an intrauterine event, and we speculate that it develops shortly after the onset of asphyxia and passage of meconium. Gasping respiratory movements may continue to mobilize meconium beyond the trachea and major airways after delivery of the infants. Meconium aspiration is an intrauterine event; therefore timing of oronasopharyngeal DeLee suctioning did not contribute to meconium aspiration syndrome in our population or change the rate of meconium aspiration syndrome. However, oronasopharyngeal DeLee suctioning before or after delivery of the chest, combined with immediate postnatal tracheal suctioning, did ameliorate the severity of meconium aspiration syndrome at our institution because no neonatal deaths occured in our study group. We therefore support the continuation of this practice. We suggest a national collaborative effort in the prevention of meconium aspiration syndrome, in which not only oronasopharyngeal DeLee suctioning but also tracheal suctioning is further evaluated in a prospective randomized contrqlled manner. We thank the pediatric residents and the nurses of the Newborn Intensive Care Unit of Good Samaritan Hospital for their assistance in completion of this study. REFERENCES I. Carson BS, Losey RW, Bowes WA, Simmons MA. Com-
bined obstetric and pediatric approach to prevent meconium aspiration syndrome. A}'I J OBSTET GnlEcoL 1976; 126:712-5. 2. Falciglia HS. Failure to prevent meconium aspiration syndrome. Obstet Gynecol 1988;71:349-53. 3. Gregory GA, Gooding CA, Phibbs RH, Tooley WHo Meconium aspiration in infants: a prospective study . .J Pediatr 1974;85:848-52.
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Delee suction and meconium aspiration syndrome
4. Ballard JL, Musial MJ, Myers MG. Hazards of delivery room resuscitation during oral methods of endotracheal suctioning. Pediatr Infect Dis 1986;5: 198-200. 5. Gage JE, Taeusch HW, Treves S, et al. Suctioning of upper airway meconium in newborn infants. JAMA 1981 ;246:2590-2. 6. Rossi EM, Philipson EH, Williams TG, Kalhan Sc. Meconium aspiration syndrome: intrapartum and neonatal attributes. AMJ OB5TET GYNECOL 1989; 161: 1106-10. 7. Stahlman MT. Acute respiratory disorders in the newborn. In: Avery GB, ed. Neonatology: pathophysiology and management of the newborn. Philadelphia: JB Lippincott, 1987:443. 8. Pfenninger E, Dick W, Brecht-Krauss D, Bitler F, Hoffmann H, Bowdler I. Investigation of intrapartum clearance of the upper airway in the presence of meconium contaminated amniotic fluid using an animal model. J Perinat Med 1984;12:57-67. 9. Dooley SL, Pesavento DJ, Dipp R, Soul ML, Tamura RK, Wiringa KS. Meconium below the vocal cords at delivery: correlation with intrapartum events. AM J OBSTET GyNECOL 1985; 153:767-70. 10. Sadovsky Y, Amon E, Bade ME, Petrie RH. Prophylactic amnioinfusion during labor complicated by meconium: a
preliminary report. AM J OBSTET GYNECOL 1989; 161: 613-7. Dawes GS, Fox HE, Leduc BM, et al. Respiratory movements and rapid eye movement sleep in the fetal lamb. J Physiol 1972;220: 119-43. Block MF, Kallenberger DA, Ken ID, et al. In utero meconium aspiration by the baboon fetus. Obstet Gynecol 1981;57:37-40. Adams FH, Desilets DT, Towers B. Control of flow of the fetal lung fluid at the laryngeal outlet. Respir Physiol 1967;2:302-5. Miller FC, Sacks D, Yeh S, et al. Significance of meconium during labor. AMJ OBSTET GYNECOL 1975;122:573-80. Cunningham RJ. Acute renal failure. In: Rudolph AM, ed. Pediatrics. Norwalk, Connecticut: Appleton & Lange, 1991:1245. Garcia-Alix A, Perlman JM. Early clinical findings in infants born with meconium stained amniotic fluid. Pediatr Res 1989;25:356. Davis RO, PhilipsJB, Harris BA, Wilson ER, Huddleston JF. Fatal meconium aspiration syndrome occurring despite airway management considered appropriate. AM J OBSTET GYNECOL 1985;151:731-6.
II. 12. 13. 14. 15. 16. 17.
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