The Effects of Low Flow and Normal Flow Desflurane Anesthesia
Condition: Anesthesia; Liver Functions; Kidney Functions; Geriatric
Study type: Interventional

Summary: 
      Aging is a physiological process. In the elderly, loss of functional reserve in all organ
      system, regression in anabolic processes and increase in catabolic processes are observed s
      (1). The number of geriatric patients is also increasing in our country. Technological
      developments in anesthesia and surgery technics show that we will provide medical services to
      more elderly patients over time(2). Cystatin C is excreted only by the kidney (7, 8). Serum
      cystatin C level is not affected by body muscle mass, age and gender. The half-life is short.
      Because of all these features, it is thought to be more sensitive than creatinine in
      evaluating kidney functions (8,9). In this study, it was aimed to compare the effects of low
      flow and normal flow desflurane anesthesia applied in geriatric patients on postoperative
      liver and kidney functions and serum cystatin C levels.
    

Detailed description: 
      This prospective, randomized-controlled, observational study was approved by the ethics
      committee of Van Yuzuncu Yıl University (Date: 16.04.2021, Decision no: 05-27). The study was
      performed according to the World Medical Association's Declaration of Helsinki. All enrolled
      patients provided written informed consent.

      In this prospective study; the patients were randomly divided into 2 groups according to the
      fresh gas flow applied. 'Group D' (n=30) was given to the low flow anesthesia group; the
      group in which normal flow anesthesia was administered was named 'Group N' (n=30).

      Before anesthesia, automatic calibration of the anesthesia device (Primus, Drager) and leak
      tests were performed. In addition, the leak test was repeated manually for each patient.
      Alarm limits of the anesthesia device; The lower limit of inspired oxygen concentration
      (FiO2) was set to 30%, upper limit of inspired CO2 to 3%, and upper limit of end-tidal carbon
      dioxide (etCO2) to 45 mmHg.

      The disconnection alarm was set to be 5 cmH2O lower than the peak pressure, the occlusion
      alarm was set to 30 cmH2O, the lower expiratory gas volume lower limit was set to be 500 mL
      below the desired minute volume (MV).

      Soda lime (Sorbo-lime, Berkim, Turkey) was used as carbon dioxide absorbent. Soda lime was
      checked frequently for color and changed at appropriate times. Disposable anesthesia circuit
      and bacterial filter were used for each case.

      Electrocardiography (ECG), peak heart rate (CTA), peripheral oxygen saturation (SpO2),
      non-invasive blood pressure and bispectral index (BIS) monitorisation (A-2000 Aspect medical
      systems, USA) were performed on all patien.

      As a standard, vascular access was established with a 20-gauge (G) intraket from the dorsal
      of the hand or antecubital fossa in each patient and, a balanced electrolyte solution was
      infused of 8-10 ml/kg/hr.

      All patients were preoxygenated with 100% O₂ for three minutes. For anesthesia induction,
      0.03 mg/kg midazolam, 1-1.5 mcg/kg fentanyl, 2 mg/kg propofol and 0.6 mg/kg rocuronium were
      administered iv. Intubation was performed after adequate muscle relaxation was achieved.
      During mechanical ventilation; Tidal volume, PEEP, respiratory rate, etCO₂, and
      inspiration:expiration ratio were adjusted to be 7-10 ml/kg, 5 cmH2O, 12-14/min, 30-40 mmHg,
      1:2 respectively.

      Both groups were given a mixture of 50% O2 + 50% air + 6-7% desflurane in a 4 L/min fresh gas
      flow (FGF) until the minimum alveolar concentration (MAC) value was 1.

      When the MAC value of desflurane was 1, FGF was reduced to 0.5 L/min (60% O2+40% dry air+8%
      desflurane) in Group D. In Group N, anesthesia was maintained by reducing FGF to 2 liters per
      minute (40% O2+60% air+6% desflurane). It was aimed to keep the MAC value between 0.9-1.1 and
      BIS values between 40-60 by titration of desflurane in all patients. Hemodynamic data, SpO2
      and BIS values of the patients were recorded. It was recorded before induction, after
      induction, when switching to low/normal flow anesthesia, and during extubation.

      Venous blood samples were obtained before induction, after surgery, and at the postoperative
      24th hour to evaluate liver and kidney functions.

      The SPSS 27.0 program was used to evaluate the data obtained in this study. In the
      descriptive statistics of the data, mean, standard deviation, median minimum, maximum,
      frequency and ratio values were used. The distribution of variables was measured with the
      Kolmogorov-Smirnov test. The mann-whitney u test was used in the analysis of quantitative
      independent data. Wilcoxon test was used in the analysis of dependent quantitative data.
      Chi-square test was used in the analysis of qualitative independent data, and the fischer
      test was used when the chi-square test conditions were not met. Statistical significance
      value was accepted as p<0.05 in all tests.
    

Intervention name(s): Low flow desflurane anesthesia (Group D)
Intervention type(s): Drug
Intervention description(s): When the MAC value of desflurane was 1, fresh gas flow was decreased to 0.5 L/min (60% O2+40% air). Hemodynamic parameters, SpO2 and BIS values were recorded after induction, at the beginning of low flow/normal flow anesthesia and every 5 minutes during surgery. The patients were observed in terms of side effects and complications during the operation and in the postoperative period. To research the liver and the kidney functions, blood samples were taken pre-induction, post-surgery, and at the postoperative 24th hour by venous route.
Other intervention name(s): Normal flow desflurane anesthesia (Group N)
Intervention MeSH terms: Anesthetics; Desflurane
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Sixty patients were included in the study. The patients were randomly divided into two groups as low flow anesthesia and normal flow anesthesia. All patients were preoxygenated. Midazolam, fentanyl, propofol and rocuronium were administered iv for induction of anesthesia. After intubation all patients were mechanically ventilated with 50%O2+50% air+7% desflurane in a 4L/min fresh gas flow until the MAC value reached to 1.
When the MAC value of desflurane was 1, the fresh gas flow was reduced to 0.5L/min (60%O2+40%air) in GroupD.
In GroupN, the fresh gas flow was reduced to 2L/min (40%O2+60% air). The anesthesia was maintained in these fresh gas flows. HR, SBP, DBP, MBP, SpO2 and BIS values were recorded preanesthesia and during surgery. To research the liver and the kidney functions, blood samples were taken pre-induction, post-surgery, and at the postoperative 24th hour by venous route.
Masking: Single (Investigator)
Primary purpose: Prevention
Keywords: Low flow desflurane anesthesia,; Liver functions; Kidney functions; Serum cystatin C levels; Geriatric patients.