Thoracic, Diseases Clinical Trial
Official title:
The Influence Of Continuous Positive Airway Pressure and Positive End-Expiratory Pressure, With A Recruitment Maneuver, On Oxygenation During One Lung Ventilation Employing A Lung Protective Ventilation Strategy.
Patients requiring one lung ventilation (OLV) for open thoracic surgery will be ventilated
(breathing performed by a breathing machine) during anesthesia using a lung protective
ventilation strategy (small breath volumes at 6ml/kg). During thoracic surgery the
anesthesiologist is able to ventilate only one lung by inserting a special breathing tube,
allowing the surgeon to operate on the non ventilated (diseased) lung. In a randomized trial
two interventions used to improve blood oxygen levels during one lung ventilation will be
compared . The two interventions are:
1. Continuous Positive Airway Pressure (CPAP) applied to the non ventilated (non breathing)
lung and
2. Positive End Expiratory Pressure following a lung Recruitment Maneuver (RM-PEEP) to the
ventilated (breathing) lung.
CPAP is performed by applying a steady flow of oxygen to the non ventilated (non breathing)
lung at a continuous gentle pressure of 5cmH20.
To perform a Recruitment Maneuver (RM) the anesthesiologist inflates the ventilated
(breathing) lung with oxygen, holding the breath for 25 seconds so all the lung is opened up.
Immediately after the recruitment maneuver PEEP will be applied. PEEP is an action which also
helps keep the lung open, maintaining the benefits achieved by the RM. It is performed by
adjusting settings on the ventilator (breathing machine). The ventilator creates and applies
a gentle pressure (5cmH20) to the ventilating lung at the end of each breath.
The outcome measure will be the oxygen content in blood (PaO2), measured in mmHg, using blood
sample analysis.
The null hypothesis is that compared to CPAP, RM-PEEP does not significantly increase the
oxygen content of blood during OLV when using a lung protective ventilation strategy.
Patients requiring one lung ventilation (OLV) for open thoracic surgery will be ventilated
intra-operatively using a lung protective ventilation strategy (small tidal volumes {Vts} at
6ml/kg Ideal Body Weight {IBW}). In a randomized, crossover trial Continuous Positive Airway
Pressure (CPAP) to the non ventilated lung or a Recruitment Maneuver (RM) followed by the
application of Positive End Expiratory Pressure (PEEP) (acronym RM-PEEP) to the ventilated
lung will be applied and blood oxygenation (PaO2) measured by arterial blood gas sampling to
determine which intervention has the most beneficial effect on PaO2 (CPAP or RM-PEEP).
CPAP will be applied at a pressure of 5cmH2O by a CPAP breathing circuit (designed for the
purpose and commonly used in anesthetic practice). The PEEP will be applied at a pressure of
5cmH20 by the operating room (OR) anesthetic machine. The RM will involve a valsalva
maneuver, held for 5 seconds at a pressure of 25cmH20, again performed using the OR
anesthetic machine.
Null hypothesis: Compared to CPAP, RM-PEEP does not significantly increase PaO2 or reduce the
incidence of hypoxia (oxygen blood saturation less than or equal to 90%), when employing a
lung protective ventilation strategy.
This study is based on our previous research (citation 12, Badner et al) in which we compared
CPAP to PEEP alone (omitting the recruitment maneuver). Here it was noted that CPAP to the
non ventilated lung improved oxygenation more than PEEP to the ventilated lung (even though
PEEP is an easier modality to provide), when employing a lung protective ventilation
strategy.
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