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Significance of Grunting Respirations in Infants Admitted to a Well-Baby Nursery
Gentry C. Yost, MD;
Paul C. Young, MD;
Karen F. Buchi, MD
Arch Pediatr Adolesc Med. 2001;155:372-375.
ABSTRACT
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Objectives (1) To determine the frequency and duration of grunting in term and
near-term newborns; (2) to determine the peripartum characteristics associated
with grunting; and (3) to compare the short-term outcomes of newborns with
and without grunting.
Design Medical record review of all newborns admitted to a well-baby nursery
during a 2-month period.
Setting University well-baby nursery for term infants, with more than 2700 deliveries
annually.
Main Outcome Measures Frequency and duration of grunting, maternal and newborn clinical characteristics,
clinical course, and length of stay.
Results Grunting respirations beginning during the first 4 hours of life were
recorded for 81 (17.4%) of 466 newborns. Fifty-five (68%) stopped grunting
within 30 minutes of birth, 69 (85%) by 1 hour, and 75 (93%) by 2 hours. More
mothers of grunting infants received intrapartum antibiotics than mothers
of nongrunters (33% vs 20%; P = .03). More grunting
infants than nongrunters received bag and mask resuscitation (15% vs 5%; P = .01). More chest radiographs, blood cell counts, and
blood cultures were ordered for grunting infants, and antibiotics were more
often given to grunting than nongrunting infants (11.1% vs 4.6%; P = .04). Grunters' length of stay exceeded that of nongrunters (72
vs 55 hours; P = .01), but only 3 were transferred
to a neonatal intensive care unit.
Conclusions All grunting infants should be carefully observed, but because nearly
all otherwise healthy term or near-term infants will stop grunting and have
a benign course, other interventions can be postponed for 1 or 2 hours to
give the newborn a chance to stop grunting or show other signs of respiratory
illness.
INTRODUCTION
GRUNTING OCCURS when a newborn exhales against a partially closed glottis.
In 1956, Silverman and Andersen1 included grunting
as part of their 5-part "retraction score," with 0 indicating no grunting;
1, "expiratory grunt heard with stethoscope only"; and 2, "expiratory grunt
heard with naked ear." Standard pediatric textbooks2, 3, 4, 5
list grunting as a sign of respiratory distress in newborns, but the peer-reviewed
pediatric literature provides no data on how frequently grunting occurs, what
characteristics are associated with it, or the outcome for infants who demonstrate
grunting in the first hours after birth. The authors had observed that grunting
in these first hours appeared to be relatively common in term and near-term
newborns and that many such newborns did not progress to significant respiratory
illness or distress.
To characterize the frequency and significance of grunting, we designed
a study with the following objectives: (1) to determine the frequency and
duration of grunting in term and near-term infants admitted to a well-baby
nursery; (2) to determine the peripartum characteristics associated with grunting
respirations; and (3) to compare the short-term outcomes of grunting newborns
with those of newborns without grunting. We hypothesized that grunting would
be relatively common, but that most newborns who demonstrated grunting without
other signs of disease would have a good outcome.
SUBJECTS AND METHODS
The study was conducted in the well-baby nursery of the University of
Utah Health Science Center, Salt Lake City. The nursery provides initial care
for all newborns with a gestational age of 34 weeks or more unless complications
are anticipated. In 1999, 2723 newborns were admitted to the well-baby nursery.
Medical records of all infants admitted to the nursery between June
23 and August 27, 1999, were reviewed (N = 474). No infants were excluded.
The period was chosen to accommodate the availability of one of us (G.C.Y.)
to collect the data. The standard postpartum procedure at the University of
Utah Health Science Center is as follows: After birth and contact with the
mother in the delivery or birthing room, the newborn is observed for a 4-hour
"transition" period in the nursery before rooming-in with the mother. Vital
signs and other relevant observations are recorded in a flow sheet by a nurse
assigned for this purpose. This nursing care flow sheet for the first 4 hours
of life contains a column for the nurse to indicate whether grunting is present.
These nursing records were used as the primary data source for this study.
In addition to the presence or absence of grunting, the following information
was extracted from the complete medical records of all mothers and infants:
birth weight; gestational age; mode of delivery; the presence of maternal
fever, prolonged rupture of the membranes, or sustained fetal tachycardia;
group B streptococcal culture results; use of intrapartum antibiotics; evidence
of meconium at delivery; and the presence of a nuchal cord. One- and 5-minute
Apgar scores, the presence of infant tachypnea, and the type of resuscitation,
if any, were also noted. Short-term outcomes included transfer to a neonatal
intensive care unit (NICU), length of stay, and discharge diagnoses.
Complete data were collected for all infants who demonstrated grunting
respirations (n = 81) and for the first 197 infants who did not exhibit grunting
respirations. This sample of 278 infants served as the primary data set for
comparison. The remainder of the nongrunting newborns (n = 188) had only outcome
data recorded. Data for the grunting and for the initial 197 nongrunting infants
were recorded in 30-minute time blocks for the first 4 hours. In addition
to grunting, maximum respiratory rate, oxygen saturation, need for supplemental
oxygen, laboratory studies performed (capillary blood gas, complete blood
cell count, blood glucose level, or hematocrit), and the initiation of antibiotic
treatment were recorded.
A  2 analysis was used for categorical variables and t tests for continuous variables. P
values greater than .05 were considered to be significant. Statistical analysis
was performed with StatView statistical software (Abacus Concepts, Berkeley,
Calif). The study was approved by the University of Utah Institutional Review
Board for the Health Sciences.
RESULTS
INCIDENCE AND DURATION OF GRUNTING RESPIRATIONS
Grunting respirations beginning at some time during the first 4 hours
of life were recorded for 81 (17.4%) of the 466 newborns. The duration of
grunting is shown in Figure 1. The
onset of grunting occurred during the first of the 8 time blocks for all but
3 of the infants, 1 who began grunting at the end of the second 30-minute
period (about 1 hour of age) and 2 in whom grunting was first noted at 2 hours
of life. Of the 78 infants who began grunting during the first 30 minutes,
54 (69%) stopped during this first time block. Another 14 (18%) stopped during
the second 30-minute period. Five infants had grunting that lasted 90 minutes.
Four of these 5 had begun grunting during the 0- to 30-minute period. The
fifth began grunting at 1 hour of age and continued into the sixth 30-minute
interval. One infant who began grunting during the first 30 minutes of life
continued for the next 120 minutes before stopping. Six infants had grunting
that lasted 3 hours or more; 5 of these began in the first 30 minutes of life,
while the sixth began at about 2 hours of age.
ASSOCIATED MATERNAL CHARACTERISTICS
Maternal characteristics evaluated for possible association with grunting
respirations in the newborn are shown in Table 1. Only the rate of intrapartum antibiotic administration
was significantly different, with 27 (33%) of the 81 mothers of grunters being
treated compared with 40 (20%) of the 196 mothers of nongrunters (P = .03). Of the 27 mothers of grunters who received intrapartum antibiotics,
6 (22%) were treated for presumed chorioamnionitis and 21 (78%) for group
B streptococcal prophylaxis. Of the 40 mothers of nongrunting infants who
received intrapartum antibiotics, 13 (33%) received antibiotics for presumed
chorioamnionitis and 26 (67%) for group B streptococcal prophylaxis (in 1
case the reason was unknown). These proportions are not significantly different
(P = .42).
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Table 1. Grunting Respirations and Maternal Characteristics
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ASSOCIATED INFANT CHARACTERISTICS
Infant characteristics examined for differences between grunters and
nongrunters are shown in Table 2.
Only the use of bag and mask ventilation during initial resuscitation was
significantly associated with grunting respirations.
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Table 2. Grunting Respirations and Infant Characteristics
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PHYSICIAN TREATMENT AND SHORT-TERM OUTCOMES
Table 3 displays differences
in treatment and outcomes of the 2 groups of infants. More laboratory tests
were ordered for grunting infants than for nongrunting ones. Chest radiographs,
complete blood cell counts, and blood cultures were all more likely to be
ordered for grunting infants. Grunters were also more likely than nongrunters
to have received antibiotics (9/81 [11.1%] vs 9/197 [4.6%]; P = .04). Of the 11 chest x-ray films obtained in the grunting cohort,
4 were read as normal, 3 were read as showing transient tachypnea of the newborn,
2 had abnormal cardiac shadows, 1 had a small effusion, and 1 was read as
showing prematurity vs pneumonia. Of the 10 chest x-ray films obtained in
the nongrunting cohort, 8 were read as normal, 1 as showing transient tachypnea
of the newborn vs atelectasis, and 1 as showing consolidation. When chest
x-ray films were categorized as "normal" or "other than normal," x-ray films
of 7 (64%) of 11 grunters were read as "other than normal" compared with 2
(20%) of 10 nongrunters (P = .04). White blood cell
counts between the grunting and nongrunting cohorts did not differ. Three
blood cultures in the study were positive, 2 from the grunting cohort. All
were considered to be contaminants (2 Staphyloccocus epidermidis and 1 Propionibacterium acnes).
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Table 3. Grunting Respirations and Short-term Outcomes
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Grunting infants remained in the hospital significantly longer than
nongrunters (72 vs 55 hours; P = .01), with a mean
difference of 17 hours. Three of the 81 grunting infants were transferred
to the NICU. One, an infant of 38 weeks' gestation who had grunting respirations
for 1 hour, continued to evidence respiratory distress after grunting ceased
and was transferred to the NICU for presumed meconium aspiration. Another
infant of 38 weeks' gestation grunted for 2 hours and stopped but, because
of a continued oxygen requirement, was transferred to the NICU for respiratory
distress and possible sepsis. The third infant transferred to the NICU was
an infant of 39 weeks' gestation who grunted continuously for the first 4
hours of life and had persistent tachypnea with an increasing oxygen requirement.
One infant from the nongrunting cohort was transferred to the NICU because
of tachypnea and the physician's concern about sepsis. Rates of transfer were
compared by means of likelihood ratio 2 analysis; the P value was .06. Because of the small numbers of transfers,
this finding should be interpreted with caution.
SHORT-TERM VS PROLONGED GRUNTING
We compared the peripartum characteristics of the 75 short-term grunters
(those whose grunting resolved within 120 minutes; in 95% it resolved within
30 minutes) with those of the 6 infants with prolonged grunting (those who
continued to grunt for 3 hours or more). Prolonged grunters were more likely
to have had a respiratory rate greater than 60 breaths/min during the first
4 hours after delivery (4/6 [67%] compared with 11/75 [15%]; P<.01) and were more likely to be transferred to the NICU (1/6 [17%]
compared with 2/75 [3%]; P<.01). There were no
differences between short- and long-term grunters with respect to birth weight,
gestational age, cesarean delivery, maternal fever, prolonged rupture of membranes,
administration of intrapartum antibiotics, presence of meconium or nuchal
cord, or need for bag and mask resuscitation. With only 6 infants in the long-term
grunting group, there is insufficient power to be confident that no differences
between the 2 groups of infants would be found if the number of infants with
prolonged grunting had been larger.
COMMENT
There is limited information regarding grunting respirations in the
pediatric literature. To understand the physiologic significance of grunting
respirations, Knelson et al6 studied the effects
of grunting respirations in dogs with and without pneumonia. The subjects
received mechanical ventilation, and an end-inspiratory pause was used to
simulate grunting respirations. The authors found that grunting produced a
mean increase in PaO2 and a mean decrease in PaCO2.
These effects were found to be less pronounced when the subjects had pneumonia.
Others have reported that grunting respirations improve oxygenation and ventilation.
Yao and colleagues7 described the respiratory
frequency, pattern, and occurrence of grunting respirations in 57 healthy
term infants from birth through the first hours of life. In their study, infants
in whom clamping of the umbilical cord was delayed were more likely to demonstrate
grunting respirations; they speculated that grunting respirations served as
a compensatory mechanism to achieve respiratory adaptation in the face of
an overdistended circulatory system. Harrison and colleagues8
studied 22 infants with hyaline membrane disease. Observing PaO2
values while the infants grunted and while intubated (a means of preventing
grunting respirations), they found that arterial oxygen tension fell during
intubation. They concluded that grunting respirations were a protective form
of breathing resulting in improved alveolar ventilation.
Although grunting respirations are most often associated with respiratory
disease, they may occur in other types of illness. Several authors have reported
that grunting in older infants and children can be an indication of severe
disease.9, 10, 11, 12
Poole et al13 found that 28 (55%) of 51 patients
between the ages of 1 month and 18 years presenting to an emergency department
with grunting respirations had a respiratory or cardiac condition, while 45%
had another cause for their grunting respirations. These other causes were
most often illnesses that were accompanied by high fever or appeared to cause
pain.
These studies support an association of grunting with serious illness
in older infants but may not be applicable to newborns with grunting respirations.
The idea for our study arose from a question posed during a morbidity and
mortality conference where the death of a term newborn nursery infant who
had several hours of documented grunting respirations was being discussed.
The question, "How long should a general pediatrician in a well-baby nursery
observe a newborn term or near-term infant with grunting respirations before
intervening?" was vigorously debated but not resolved. Although this study
does not provide a direct answer to this question, it provides some insight
into the frequency and natural course of grunting respirations in term infants
admitted to a well-baby nursery.
We hypothesized that grunting respirations would be relatively common
in this population, and we found that 17% of infants in the well-baby nursery
demonstrated grunting respirations at some point during their first 4 hours
of life. The onset in 78 (96%) of the 81 was within the first 30 minutes of
life.
The second hypothesis was that most infants who grunted would have a
good outcome. We found that 69% of the infants stopped grunting within 30
minutes of birth, 85% by 1 hour, and 93% by 2 hours. Although more laboratory
tests were ordered for grunting infants, more grunting infants received antibiotics,
and they remained in the hospital longer, only 3 were believed by their physicians
to be ill enough to require transfer to the NICU. Two did well, but 1 of these
infants developed persistent fetal circulation and had a prolonged NICU course.
Our study has some important limitations. First, data collection was
retrospective and based on the assessments and charting accuracy of the nursing
staff. Many nurses were working in the nursery, and they may have varied in
their categorization or charting of grunting or other symptoms. We believe,
however, that if grunting was not recorded, it would be more likely to have
been in infants in whom grunting was brief and who had a good outcome; thus,
our study could have underestimated the incidence of grunting while overestimating
the number of adverse outcomes. Second, adverse outcomes in this population
of term and near-term infants were very infrequent; thus, our study does not
have sufficient power to make reliable determinations of sensitivity, specificity,
or predictive values regarding grunting and its association with serious illness.
Despite these limitations, we believe that our study can help inform
decision making in a well-baby nursery when an infant is noted to exhibit
grunting during transition. Careful observation of grunting infants, particularly
for other evidence of respiratory problems, is warranted, but other interventions
can be postponed for 1 or 2 hours to give the grunting a chance to resolve.
If grunting persists, or the child's condition deteriorates during this period,
further investigations for treatable causes of grunting, eg, sepsis, should
be undertaken.
AUTHOR INFORMATION
Accepted for publication November 17, 2000.
Presented as a poster at the Pediatric Academic Societies and American
Academy of Pediatrics joint meeting, Boston, Mass, May 14, 2000.
From the Departments of Pediatrics, University of California, Fresno
(Dr Yost), and University of Utah, Salt Lake City (Drs Young and Buchi).
Corresponding author and reprints: Karen F. Buchi, MD, Department
of Pediatrics, University of Utah, 50 N Medical Dr, Salt Lake City, UT 84132
(e-mail: karen.buchi{at}hsc.utah.edu).
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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
Grunting Respirations in Newborns
JWatch General 2001;2001:5-5.
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