Pneumoperitoneum and Cerebral Oxygenation

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.

Eligibility Criteria:
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