Diferentes frações inspiradas de oxigênio e hiperinsuflação mecânica na aspiração endotraqueal aberta : impacto na oxigenação e ventilação pulmonar
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2015-12-16Autor
Vianna, Jacqueline Rodrigues de Freitas
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Endotracheal suction (ES) in mechanically ventilated patients is required for
maintaining a patent airway. Open circuit endotracheal suction (OCES) may cause
greater damage to respiratory mechanics and gas exchange. There is little evidence
about the impact of the use of oxygen concentrations below 100% and the expiratory
pressure-zero end expiratory pressure (PEEP-ZEEP) technique at increasing
oxygenation and maintaining adequate ventilation during the OCES. In addition studies
were not found concerning need or not of hyperoxygenation associated with the PEEP-
ZEEP and the effectiveness of isolated hyperoxygenation with oxygen concentration
20% above the baseline, thus justifying the studies of this thesis. Study I aimed to
evaluate whether the 20% oxygen concentration of inspired oxygen fraction (FiO2)
above the baseline avoids hypoxemia compared the offer to 100% and determine the
impact of OCES on pulmonary ventilation in critical patients on mechanical ventilatory
support. This randomized crossover study involved 68 patients in an adult intensive care
unit (ICU), intubated, mechanically ventilated and placed in the two intervention
sequences: Hyperoxygenation using 20% above FiO2 (FiO2 20%) and
Hyperoxygenation using 100% FiO2(FiO2 100%). Hyperoxygenation was applied 1 min
before each of the 5 ES and 1 min after OCES. The studied variables were measured
pre, immediately after and 1min, 2 min and 30 min after OCES. There was a significant
intra-group increase in immediate post FiO2 20% and 100% on peripheral oxygen
saturation (SpO2), carbon dioxide (CO 2) exhaled at the end of expiration (ETCO2),
partial pressure of CO2 in the mixed expired air (PeCO2 ), heart rate (HR), mean arterial
pressure (MAP), and in the tidal volume of CO2 (VtCO2) only for the FiO2 20%.
Intergroup in the immediate post in VtCO 2, ETCO2 and SpO 2 restoring the pre
intervention values 30 min after measurement. It was concluded that an oxygen
concentration of 20% above baseline FiO2 for patients with need of prior offer 60%
effectively avoided hypoxemia and volumetric capnography analysis confirms that
changes in pulmonary ventilation in OCES in critical patients are transient and
reversible within 30 min. These findings also support the implementation of Study II
which aimed to verify behavior of peripheral oxygen saturation (SpO2) and exhaled end-
expiratory CO2 (ETCO2), for the OCES procedure, using PEEP-ZEEP baseline FiO2
versus PEEP-ZEEP hyperoxygenation using 20% above FiO 2. This randomized
crossover study involved 38 patients in an ICU, intubated, mechanically ventilated and
placed in the two intervention sequences: PEEP-ZEEP with baseline FiO2 (PEEP-ZEEP
FiO2 baseline) and PEEP-ZEEP with 20% above FiO2 (PEEP-ZEEP hyperoxygenation).
Hyperoxygenation was applied 1 min before each of the 5 procedures and 1 min after
OCES. PEEP-ZEEP with 3 series before each of the 5 ES. The studied variables were
measured pre, immediately after and one, two and 30 min after OCES. There was
significant increase in SpO2 on PEEP-ZEEP hyperoxygenation, with maintenance of
adequate levels on PEEP-ZEEP FiO2 baseline no change in ETCO2 in both
interventions. Significant difference was found in intergroup SpO2 post 1 min of
hyperoxygenation, immediate post, post 1and 2 min of OCES. Significant difference
was found in intergroup SpO2 post 1 min of hyperoxygenation, immediate post, post 1
and 2 min of OCES. It was concluded that the PEEP-ZEEP technique, when well
indicated, associated or not to hyperoxygenation is effective to avoided the fall of SpO2
and maintain levels of ETCO2, minimizing the impairment in the ventilation caused by
OCES.