Effect of Type of General Anesthesia Maintenance on Exhaled Nitric Oxide and Eosinophil Blood Count
Condition: Anesthesia; Exhaled Nitric Oxide; Eosinophil Blood Count
Study type: Interventional

Summary: 
      -  Nitric oxide (NO) is a free radical in gas state which plays an important role in a
           variety of processes relevant to respiratory physiology. It represents a means of
           detecting airway hyperresponsiveness and appears to have a strong correlation with the
           eosinophilic infiltration of the airway. Patients who suffered bronchospasm or
           laryngospasm intraoperatively or postoperatively showed higher levels of exhaled NO.

        -  Propofol modifies NO production by stimulating the constitutive synthesis of NO and by
           inhibiting the inducible production of NO. It seems to exert protective effects on acute
           lung injury (ALI) in experimental models and it can possibly reduce exhaled NO. There is
           also evidence that some intravenous anesthetic agents can influence chemotaxis of
           eosinophils in vitro.

        -  Variation of exhaled NO and eosinophils in surgical patients undergoing anesthesia has
           not been studied before. Therefore, the aim of this study will be to investigate the
           differential impact of maintenance of general anesthesia with propofol versus
           maintenance with sevoflurane on exhaled NO and eosinophil blood count.
    

Detailed description: 
      -  Nitric oxide (NO) is a free radical in gas state which plays an important role in a
           variety of processes relevant to respiratory physiology. NO is produced by several
           cellular types (epithelial, endothelial, neuronic, inflammatory cells) (Gaston B, et al,
           1994), it represents a means of detecting airway hyperresponsiveness and appears to have
           a strong correlation with the eosinophilic infiltration of the airway (Warke TJ, et al,
           2002). Patients who suffered bronchospasm or laryngospasm intraoperatively or
           postoperatively showed higher levels of exhaled NO (Saraiva-Romanholo BM, et al, 2009).

        -  Propofol modifies NO production by stimulating the constitutive synthesis of NO and by
           inhibiting the inducible production of NO (González-Correa JA, et al, 2008). It seems to
           exert protective effects on acute lung injury in experimental models (Chu CH, et al,
           2007; Chen HJ, et al, 2008) and possibly reduces exhaled NO (Fijałkowska A, et al,
           2012). There is also evidence that some intravenous anesthetic agents can influence
           chemotaxis of eosinophils in vitro (Krumholz W, et al, 1999)

        -  Variation of exhaled NO and eosinophils in surgical patients undergoing anesthesia has
           not been studied before. Therefore, the aim of this study will be to investigate the
           differential impact of maintenance of general anesthesia with propofol versus
           maintenance with sevoflurane on exhaled NO and eosinophil blood count.

        -  Patients with ASA score I-III who undergo thyroidectomy under general anaesthesia will
           participate in this study. Thyroidectomy has been chosen for the following reasons: a)
           there will be consistency in both the surgeon and the type of surgery and as a result
           manipulations and surgical stress will be similar for all patients and b) abdominal
           walls are not manipulated at all during thyroidectomy and therefore postoperative
           measurement of exhaled NO will be easier and painless for patients.

        -  Patients will be randomized to one of two groups: one group with general anesthesia
           maintenance based on an intravenous agent (propofol) and a second group with general
           anesthesia maintenance based on an inhalational agent (sevoflurane).

        -  When patients arrive in the operating room, standard monitoring will be applied and
           exhaled NO will be measured immediately before induction with the NObreath® device (
           Antus B, et al, 2010, Pisi R, et al, 2010) and a blood sample will be taken for
           eosinophil count measurement.

        -  During the patients' stay in the PACU and when Aldrete score is ≥8, exhaled NO will be
           measured again and a second blood sample will be taken. Exhaled NO will be measured
           again 24 hours postoperatively.

        -  The clinical implications of this study lie in the fact that it may provide further
           information on the effects of anesthetics (intravenous and inhalational) on the
           physiology and pathophysiology of the respiratory system. In addition, new evidence may
           come to light about the relationship between intravenous and inhalational agents and NO
           production.
    

Intervention name(s): maintenance with sevoflurane; maintenance with propofol
Intervention type(s): Procedure; Procedure
Intervention description(s): in patients allocated to the sevoflurane group, general anesthesia will be maintained with sevoflurane; in patients allocated to the propofol group, general anesthesia will be maintained with propofol
Intervention MeSH terms: Propofol; Sevoflurane
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Basic Science