Pneumoperitoneum and Cerebral Oxygenation

An Analysis of Cerebral Oximetry After Low Pressure Compared With Standard Pressure Pneumoperitoneum in Patients Undergoing Laparoscopic Nephrectomy: A Prospective Randomized Parallel-Group Study

In this study, the changes in cerebral oxygen saturation due to low and high pressure pneumoperitoneum implementation were measured in patients who underwent laparoscopic nephrectomy. This prospective, double-blind study included 62 American Society of Anesthesiologists (ASA) PS class I-III patients aged 18-65 years who underwent laparoscopic nephrectomy (simple, partial, or radical). Patients were randomly classified into 2 groups: Group LP (n = 31) included patients who were treated with low pressure pneumoperitoneum (8 mmHg) and Group SP (n = 31) included patients who were treated with standard pressure (14 mmHg). A standard anesthesia protocol was used in both groups. Bilateral rSO2 values were recorded at baseline, at 1 minute after induction, and then every 5 minutes until the patient went to the recovery unit. Data for mean arterial pressure (MAP), peak heart rate (HR), peripheral oxgen saturation (SpO2), and end-tidal carbon dioxide (ETCO2) were also recorded at the same time intervals. Arterial blood gas was analyzed in the 5th minute after induction (t1) while the patient was in the supine position, in the 5th and 30th minutes after insufflation (t2, t3) while the patient was in the lateral semi-oblique position, and again 10 minutes after desufflation (t4) while the patient was in the supine position. Patient demographic data, duration of anesthesia, duration of surgery, lateral position time, pneumoperitoneum time, and recovery time were also recorded. used in both groups. Bilateral rSO2 values were recorded at baseline, at 1 minute after induction, and then every 5 minutes until the patient went to the recovery unit. Data for mean arterial pressure (MAP), peak heart rate (HR), SpO2, and ETCO2 were also recorded at the same time intervals. Arterial blood gas was analyzed in the 5th minute after induction (t1) while the patient was in the supine position, in the 5th and 30th minutes after insufflation (t2, t3) while the patient was in the lateral semi-oblique position, and again 10 minutes after desufflation (t4) while the patient was in the supine position. Patient demographic data, duration of anesthesia, duration of surgery, lateral position time, pneumoperitoneum time, and recovery time were also recorded.

A total of 62 American Society of Anesthesiologists (ASA) PS class I-III patients between the ages of 18 and 65 years who were scheduled for elective laparoscopic nephrectomy (simple, partial, or radical) were included in the study. A standard anesthesia protocol was used in both groups. Patients did not receive any sedative premedication. Upon entering the operating room, they underwent electrocardiogram, non-invasive blood pressure, peripheral oxygen saturation (SpO2), rSO2 (INVOS TM 5100C oximeter; Covidien), and neuromuscular monitoring (TOF-WatchTM SX; Organon, Dublin, Ireland). Subsequently, anesthesia was induced with propofol (1.5-2.5 mg/kg) and remifentanil (1 mcg/kg IV bolus for 30-60 seconds, then 0.25 mcg/kg/min), and rocuronium (1.2 mg/kg). Anesthesia was maintained with O2/Air (fraction of inspired oxygen of 0.40; inspiratory fresh gas flow of 2 L/min), sevoflurane (1 minimum alveolar concentration), and remifentanil IV infusion (0.1-0.25 mcg/kg/min). Radial arterial cannulation was also applied for arterial blood gas analysis and continuous blood pressure measurement. A mechanical ventilator (Draeger FabiusTM Plus anesthesia Workstation, Draeger Medical, Lübeck, Germany) was used at settings of tidal volume 7-8 mL/kg, inspirium/exprium expiratory ratio 1:2, and positive end-expiratory pressure of 5 cmH2O. With these settings, pre-insufflation Sp02 values were maintained at >96%, while the respiratory rate was determined with end-tidal CO2 (ETCO2) of 32-37 mmHg. These ventilator settings were maintained throughout the operation. CO2 insufflation was performed using the closed Veress needle technique with electronic laparoflators in the patients who were placed in lateral semi-oblique (60°) and some flexion (jackknife) positions before the surgery was started. Intra-abdominal pressure was maintained at 8 mmHg in Group LS and at 14 mmHg in Group SP throughout the surgery. During the operation, a neuromuscular blockade was achieved with rocuronium infusion (0.3-0.4 mg/kg/hour) with a post-tetanic count of zero. At the end of the case, extubation was provided by decurarizing the rocuronium with a combination of 0.02mg/kg atropine and 0.04 mg/kg neostigmine. All patients were followed up with nasopharyngeal temperature monitoring and were actively warmed using a forced-air warming system to ensure normothermia throughout the surgery. Patients were followed up in the recovery unit at the end of the surgery until their modified Aldrete score reached ≤9. Hemodynamics The data of mean arterial pressure (MAP), peak heart rate (HR), SpO2, and ETCO2 were recorded at baseline, at 1 minute after induction, and then every 5 minutes until the patient went to the recovery unit. MAP and HR values were kept at ±20% of preoperative values by changing the remifentanil infusion rate. Hypotension MAP was defined as <60 mmHg and bradycardia HR as 45 beats/minute, and these were treated with noradrenaline 4-8 mcg, atropine 0.5 mg. Patients who required noradrenaline or atropine more than twice were excluded from the study.

The patients were randomly classified into 2 groups. The patients given the low-pressure pneumoperitoneum (8 mmHg) treatment were called Group LP (n = 30), and the patients given the standard pressure treatment (14 mmHg) were called Group SP (n = 30). Each patient and the anesthesiologist responsible for that patient's anesthesia management were blinded to the group assignments.

Patients were randomly classified into 2 groups using opaque sealed envelopes. Randomization was performed using a computer-generated random number list, and a statement indicating the patient's group was placed in a closed envelope numbered according to the result. Each patient was asked to choose an envelope, and the patients were assigned to the study according to the group written in the envelope.

The rSO2 measurements were made using the near-infrared spectroscopy (NIRS) method. For this, prior to induction, the cerebral oximetry sensor was placed at least 2 cm above the eyebrows and 3 cm from the midline in accordance with the manufacturer's instructions. Measurements were recorded at baseline, at 1 minute after induction, and then every 5 minutes until the patient went to the recovery unit. Baseline values were accepted as measurements in the last 30 seconds of preoxygenation for 3 minutes with 80% oxygen before induction. Cerebral desaturation was defined as a decrease in the rSO2 value of more than 25% from the baseline value (if the baseline value is <50, the decrease should be more than 20%), with this condition lasting ≥15 seconds.

The rSO2 value changes were recorded from baseline until the patient was referred to the recovery unit, up to 160 minutes.

The pH value was measured in the 5th minute after induction (t1) while the patient was in the supine position, in the 5th and 30th minutes after insufflation (t2, t3) while the patient was in the lateral semi-oblique position, and again 10 minutes after desufflation (t4) while the patient was in the supine position.

The pH values of the patients were recorded after anesthesia induction until 10 minutes after desufflation, up to 140 minutes.

The PO2 value was measured in the 5th minute after induction (t1) while the patient was in the supine position, in the 5th and 30th minutes after insufflation (t2, t3) while the patient was in the lateral semi-oblique position, and again 10 minutes after desufflation (t4) while the patient was in the supine position.

The oxygen partial pressure values of the patients were recorded after anesthesia induction until 10 minutes after desufflation, up to 140 minutes.

The PCO2 value was measured in the 5th minute after induction (t1) while the patient was in the supine position, in the 5th and 30th minutes after insufflation (t2, t3) while the patient was in the lateral semi-oblique position, and again 10 minutes after desufflation (t4) while the patient was in the supine position.

The carbon dioxide partial pressure values of the patients were recorded after anesthesia induction until 10 minutes after desufflation, up to 140 minutes.

The Hg value was measured in the 5th minute after induction (t1) while the patient was in the supine position, in the 5th and 30th minutes after insufflation (t2, t3) while the patient was in the lateral semi-oblique position, and again 10 minutes after desufflation (t4) while the patient was in the supine position.

The hemoglobin values of the patients were recorded after anesthesia induction until 10 minutes after desufflation, up to 140 min.

The data of the mean arterial pressure were recorded at baseline, at 1 minute after induction, and then every 5 minutes until the patient was referred to the recovery unit.

The mean arterial pressure was recorded from baseline until the patient was referred to the recovery unit, up to 160 minutes.

The data of heart rate were recorded at baseline, at 1 minute after induction, and then every 5 minutes until the patient was referred to the recovery unit. The MAP and HR values were kept at ±20% of the preoperative values by changing the remifentanil infusion rate. Hypotension MAP was defined as <60 mmHg and bradycardia HR as 45 beats/minute, and were treated with noradrenaline 4-8 mcg and atropine 0.5 mg. Patients who required noradrenaline or atropine more than twice were excluded from the study.

The heart rate was recorded from baseline until the patient was referred to the recovery unit, up to 160 minutes.

The SPO2 data were recorded at baseline, at 1 minute after induction, and then every 5 minutes until the patient was referred to the recovery unit.

The oxygen saturation was recorded from baseline until the patient was referred to the recovery unit, up to 160 minutes.

Surgical time was defined as the time elapsed from the time the trocar insertion was completed until the surgery was completed and the trocars were removed.

The data for EtCO2 were recorded at baseline, at 1 minute after induction, and then every 5 minutes until the patient was referred to the recovery unit.

The end-tidal carbon dioxide partial pressure was recorded from baseline until the patient was referred to the recovery unit, up to 160 min

The recovery time was defined as the time from discontinuation of sevoflurane and remifentanil to extubation at the end of the surgical procedure.

Inclusion Criteria: Patients scheduled for laparoscopic nephrectomy (simple, partial, or radical) The American Society of Anesthesiologists (ASA) physical status class I-III Exclusion Criteria: Cerebrovascular diseases Neurological disorders Uncontrolled diabetes or hypertension Advanced organ failure Baseline peripheral oxygen saturation (SpO2) less than 96% Patients with hemoglobin <9 g/dL

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