4. Discussion
In the results obtained from this
study, the spontaneous pushing associated with pursed lips breathing
showed no difference for the occurrence of episiotomy, perineal
lacerations, the duration of the second stage of labor, vaginal,
Cesarean or instrumental delivery, when compared to directed pushing.
There were no cases of postpartum hemorrhage and maternal blood pressure
changes. However, there was a decrease in the duration of the maternal
pushing and a difference in maternal anxiety in the spontaneous pushing
group with pursed lips breathing. There was no difference in pain,
fatigue, and maternal satisfaction. There were no events related to
neonatal outcomes.
The expulsive stage is considered a strong indicator of long-term
impairments of pelvic floor and bladder functions [18-22]. However,
the present study showed no difference between the groups regarding
episiotomy and perineal lacerations associated with the type of pushing,
confirming the findings of a meta-analysis [2] comprised of five
studies with 2.320 women in which no difference in episiotomy occurrence
was observed RR 0,95; CI95% 0,87 to 1,04) as well as for grade 3 or 4
perineal lacerations (RR 0,94; CI95% 0,78 to 1,14), as analyzed from
seven studies with 2.775 women. These data differ from a prospective
cohort and a randomized clinical trial [22,23] published after that
meta-analysis, which evidenced the association of directed pushing with
VM maintained for 10 seconds or more with a significant increase in the
number of episiotomies and grade 3 and 4 perineal lacerations [24].
It was hypothesized that the possible effects of pursed lips breathing
would interfere directly in the pelvic floor muscles, since this
exercise causes a change in the recruitment pattern of respiratory
muscles, increasing the recruitment of accessory muscles of the chest
wall and the activity of the abdominal muscles throughout the
respiratory cycle, simultaneously decreasing the recruitment of
diaphragmatic and pelvic floor muscles [25]. Therefore, one can
conclude that the effect of that breathing pattern on pelvic floor
muscles depends on the intensity of the abdominal muscles recruitment as
the maneuver can be performed with a strong contraction of those
muscles, depending on professional instruction and stimulus.
The intensity of abdominal muscles contraction will influence
intra-abdominal pressure (IAP). When contracting the abdominal muscles,
the diaphragm rises, while the pelvic floor muscles move downwards
[26]. Also, in situations of strong abdominal muscles contractions,
the diaphragm moves upwards, and the increase in IAP induces a
contraction of the pelvic floor muscles [27].
Therefore, considering that the pelvic floor muscles do not contract by
themselves, but in cooperation with the muscles around the abdominal
area [28], we believe that this reasoning could be applied during
the execution of pursed lips breathing, thus promoting the same effects,
which can help the pushing in caudal direction [29].
The duration of the second stage of labor has been discussed as an
important aspect of parturition, as the ideal duration for this stage is
sought. The factors that influence the duration of this stage have been
studied for the development of recommendations such as the breathing
patterns used during expulsive efforts. There is no consensus yet
regarding these practices and the ideal duration of this stage. It is
estimated, though, that the longer the duration, the greater the
maternal-fetal repercussion [18,24,30].
When evaluating the duration of the second stage of labor there were no
differences regarding the type of pushing. These findings are similar to
those of an aforementioned meta-analysis [2], which included six
studies comparing the duration of that stage of labor associated with
spontaneous pushing or with the directed pushing with VM. A total of 667
nulliparous women were evaluated, initially showing no difference in
expulsive stage duration (MD 10.26 minutes; CI95%: -1,12 to 21,64).
However, after sensitivity analysis, due to inadequate randomization,
based on four studies with 494 women, a decrease in the duration of the
expulsive stage with directed pushing was observed (MD:17,62; CI95%:
5,28 to 29,95). Those findings were yet considered inconsistent as they
presented high heterogeneity due to methodological and statistical
limitations, thus with a high association to random effects for those
affirmations.
In another retrospective cohort study [22] conducted in Australia
with 19.212 women a longer duration of the second stage of labor was
observed for those who used the directed pushing when compared to the
spontaneous pushing, that duration being 14.4 minutes (95%CI 12.0-16.8)
for the nulliparous and 8.0 minutes (95%CI 6.8-9.2) for the
multiparous. A randomized clinical trial [18] with 108 women
corroborated the findings of the previous meta-analysis [2]
regarding the expulsive period duration. Therefore, the discussion about
the effect of the type of pushing on the duration of the expulsive
period persists.
The duration of maternal pushing is another aspect that can influence
maternal-fetal well-being and perineal integrity [31-33]. The women
from our study who performed spontaneous pushing with pursed lips
breathing showed a 3.2-minute reduction of the expulsive effort. This
finding was similar to those of a meta-analysis [2] that analyzed
pushing duration based on two studies with a total of 169 women,
observing a decrease of 9.76 minutes (MD -9.76 minutes; 95%CI -19.54 to
0.02). However, after sensitivity analysis based on a study with 69
women, there was a 15-minute reduction in pushing duration for the
spontaneous pushing group (MD -15,22 minutes; 95%CI -21,64 to -8,80).
This analysis was based on one study only with a small sample and
therefore should be interpreted with caution [2].
Favoring the discussion about the importance of these outcomes, a cohort
[34] that analyzed 57.267 deliveries concluded that a maternal
pushing more than 30 minutes long during the second stage of labor, and
an expulsive stage more than one hour long are the potential factors for
maternal and neonatal morbidities, especially postpartum hemorrhage, as
well as uterine atony and cervical and perineal lacerations. This study
recommends caution regarding obstetric interventions and better
analyzing expectant management during the second stage of labor.
There was no difference between the types of pushing and delivery route
or the need for instrumentalization. These data are similar to those
found in the literature [2]. When analyzing research on pain,
anxiety, and maternal fatigue in the second period of labor there is no
consistent evidence about a direct association with the type of pushing.
It is understood, however, that those outcomes might influence labor
progression, as the stress generated by these sensations result in a
greater release of catecholamines, fatty acids, and lactate, which can
reduce the effectiveness of uterine contractions, possibly leading to
prolonged labor, and consequently to dystocia, instrumentalization,
higher post-partum hemorrhage risk, fetal distress and negative labor
experience for the woman [32,34,35].
In our study, women who carried out spontaneous pushing with pursed lips
breathing showed lower anxiety levels when compared to those on the
control group. This result was seen because the more encouraged to do
directed pushing with VM, the less physiological was the labor, thus
increasing maternal distress following the release of hormones such as
catecholamines and adrenaline, responsible for increasing maternal
anxiety [16].
The type of maternal pushing did not influence neonatal outcomes in this
study. This was expected since the apnea duration was lower than what is
found in literature, which estimates that 7 to 8 seconds of apnea with
high intrathoracic and abdominal pressures can already interfere in
uteroplacental oxygen delivery, which can lead to fetal distress
[36-43].
Not collecting data about the posture adopted by the parturient can be
cited as a limitation of this study. That data can influence both the
duration of the second stage of labor and the pushing. External
conditions related to the hospital environment, such as noise or
collective hospitalization, may have distracted the parturient’s focus
on spontaneous pushing and breathing patterns orientations.
Nevertheless, it is important to emphasize that there was no follow-up
by the doulas of the service in any of the groups.
It is noteworthy that the exercises were performed by physical
therapists. As we know, the individual must be well instructed by the
professional to properly perform the technique. The technique is limited
to 3 to 5 breaths, as prolonging it causes fatigue of the respiratory
muscles and significantly lower levels of carbon dioxide, potentially
leading to a decrease in perfusion to the brain, causing syncope.
Without the proper use of pursed lips breathing an individual could
exacerbate air and carbon dioxide retention [44].
In conclusion, spontaneous pushing with pursed lips breathing was not
effective in reducing episiotomy. However, pushing duration decreased by
3.2 minutes, also showing a difference in maternal anxiety. This result
may indicate its use for emotional control when compared to directed
pushing. As an implication for physical therapy practice, these findings
may signal an attitude in decision-making about guiding the breathing
pattern in the expulsive stage.
Disclosure
of interests
The study has no financial and religious interest, however, there is
personal interest to know if the use of the spontaneous pushing with
pursed lips breathing improves maternal and neonatal outcomes, as well
as, in the political scope of building public and scientific interest,
in improving conduct during labor.