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of 32.8%, between 28 and 90 days, in the Supine group, and
16% in the Prone group, with a relative risk reduction of
approximately 50%, and 16% absolute risk reduction. Five
years of training and experience of the team led to mini-
mal complications.
Reports in the literature suggest that the incidence
of adverse events is significantly reduced with a trained
team, experienced in the process.
4,9,10,27
By analyzing the studies, there are some important con-
siderations for clinical practice concerning the mandatory
use of protective mechanical ventilation, prolonged dura-
tion of prone positioning and the need for team training.
M
ethod
The study method included search on the following elec-
tronic databases: Medline, Lilacs and Cochrane Library.
Original research or systematic reviews were retrieved, with-
out restrictions on language, including articles from 1995
to November 2, 2014. Studies that were excluded used pa-
tients younger than 18 years or investigations in animals.
The following MESH terms were used: (“prone
position”[MeSH Terms]) OR Prone [TextWord]) OR
prone[Text Word]) OR proning[Text Word])) AND ((“In-
tensive Care”[Mesh]) OR “Intensive Care”[Text Word])
AND (“Respiratory Distress Syndrome, Adult”[MeSH
Terms]) OR Respiratory Distress Syndrome, Adult[Text
Word]) OR ARDS [Text Word]).
L
iterature
review
Indications
Patients who presented with moderate or severe ARDS
with a PaO
2
/FiO
2
ratio ≤150 mmHg, refractory hypox-
emia (PEEP >10 cmH
2
O and FiO
2
>60%) in the first 12-
24 hours on protective mechanical ventilation (MV), and/
or difficulty in maintaining protective mechanical ven-
tilation (alveolar distension pressure ≤ 15 cmH
2
O, pla-
teau pressure <30 cmH
2
O, AFV (air flow volume) of 4-6
mL/kg of ideal weight and pH >7.15), and/or those pa-
tients with right ventricular dysfunction (VD) on echo-
cardiography.
9,10,29,30
Contraindications
•
•
Absolute contraindications: Hemodynamic instabili-
ty (regarded as progressive elevation of the vasopres-
sor), acute arrhythmia (need to reassess, when reversed
or controlled), pregnancy (second or third trimester),
face trauma or surgery, maxillofacial polytrauma (frac-
ture of the pelvis, external fixation of fractures, rib or
sternum fracture), intracranial hypertension, frequent
convulsions, instability of the spine, abdominal com-
partment syndrome, recent sternotomy, cardiac sur-
gery, ophthalmic surgery (increased intraocular pres-
sure) and recent abdominal surgery or intestinal
ischemia.
•
•
Relative contraindications: Bronchopleural fistula, he-
moptysis/alveolar hemorrhage, recent tracheostomy
(within the first 24 hours), significant abnormalities of
the ribcage/kyphoscoliosis; high intra-abdominal pres-
sure above 20 mmHg, without signs of compartmental
syndrome and pregnancy (in the first trimester).
9,10,18,29,31
Start time and duration of prone positioning
The biggest benefit of prone positioning occurs in the ear-
ly stage of moderate or severe ARDS. Several studies have
applied the position in the first 12-24 hours of early diag-
nosis of ARDS, after stabilization of symptoms.
4,10,29,31
The duration of the position seems to be responsible
for the reduction in mortality.
4,13,14
A recent clinical trial
has applied this procedure for 16-20 hours, with an aver-
age time of 17 hours and a significant reduction in the
absolute risk (16%) of death.
4
Therefore, the current literature suggests that prone
positioning should be performed in the first 12-24 hours
of diagnosis of moderate or severe ARDS, after stabiliza-
tion of the symptoms, and that the duration of the pro-
cedure must be no less than 16 hours.
Response criteria to prone positioning
Response to prone positioning should be assessed using
blood gas tests collected after 2 hours of prone, and pa-
tients who have increases in the PaO
2
/FiO
2
ratio of 20
mmHg or an increase in PaO
2
>10 mmHg compared with
supine position are considered responsive.
4,10,30
Time for stopping prone positioning
Recently, Guerin et al.
4
suggest a daily re-evaluation of
the need for the prone positioning. The procedure should
be stopped when ventilation or complications improve.
Ventilatory improvement
•
•
PaO
2
/FiO
2
ratio >150 mmHg with PEEP ≤10 cmH
2
O
and FiO
2
<60% in supine position, for at least 4 hours
after the end of the last prone session;
•
•
decreased PaO
2
/FiO
2
ratio greater than 20% in com-
parison to the supine position after two prone ses-
sions.
Complications
•
•
dislocation of the respiratory prosthesis;
•
•
obstruction of the endotracheal tube, hemoptysis;