These robot-assisted cardiac surgeries usually require single-lung ventilation (SLV) to facilitate surgical exposure. SLV creates ventilation/perfusion mismatch and shunt (Qs:Qt) through the collapsed lung and leads to hypoxemia. Pulmonary gas exchange often deteriorates after cardiopulmonary bypass (CPB) because of ischemic tissue damage. In some cases, severe hypoxemia may require the cessation of surgical procedures and the initiation of double-lung ventilation to improve oxygenation. In this study, the investigator applied the continuous positive airway pressure (CPAP) or the high-frequency low-volume ventilation (HFLVV) to the non-dependent lung (differential ventilation) during the weaning from CPB. The investigator hypothesized that the differential ventilation would produce the least interference with the surgeon's exposure and better oxygenation. The investigators evaluate the airway pressure, shunt fraction, PaO2/FiO2, cerebral oximetry, surgical field condition and the length of stay in intensive care unit of patients underwent the robot-assisted cardiac surgery.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
SINGLE
Enrollment
56
When the hypoxemia occurs during sing lung ventilation in robot-assisted cardiac surgery, the non-dependent lung will be ventilated with normal tidal volume in conventional ways and the surgery procedure have to be ceased. In this trial, the non-dependent lung will be ventilated with the continuous positive airway pressure (CPAP) or the high-frequency low-volume ventilation (HFLVV) to prevent the hypoxemia.
Daping Hospital, Army Medical University
Chongqing, Chongqing Municipality, China
Changes of arterial PaO2
Arterial PaO2 (in mmHg) defined as a measurement of partial pressure of oxygen in arterial blood
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of PaO2/FiO2 ratio
PaO2/FiO2 ratio defined as the ratio of PaO2 to fractional inspired oxygen (FiO2 expressed as a fraction)
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of Heart rate
Heart rate in beat per minute
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV
Changes of mean blood pressure
mean blood pressure in mmHg
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of cardiac stroke volume variation
Cardiac stroke volume variation in percentages
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of venous pressure of jugular vein
Venous pressure of jugular vein in cmH2O
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of tidal volume
Tidal volume of both lungs in milliliter
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of respiratory rates
Respiratory rates of both lungs in breath per minute
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of airway pressure
Airway pressure of both lungs in mmHg
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of end-tidal carbon dioxide tension
End-tidal carbon dioxide tension in mmHg
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of blood oxygen saturation
Blood oxygen saturation of both upper and lower extremities in percentages
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of the pulmonary shunt fraction
Qs/Qt = ((CcO2 - CaO2) / (CcO2 - CvO2)) \* 100
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of regional cerebral oxygen saturation
regional cerebral oxygen saturation in percentages
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
Changes of the surgical field
The surgeon's evaluation of the surgical field, graded from 0 (no interference) to 3 (maximal interference)
Time frame: 5 min after induction of anesthesia during DLV, 5 min after SLV, 5 min after HFLVV, 5 min after CPB flow reduced to 1/3, 5min after CPB flow reduced to 2/3, 15min after resuming of DLV]
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