Research Article: Immunomodulatory Effects of Anesthetics during Thoracic Surgery

Date Published: October 27, 2011

Publisher: Hindawi Publishing Corporation

Author(s): Khaled Mahmoud, Amany Ammar.


Background. One-lung ventilation (OLV) during thoracic surgery may induce alveolar cell damage and release of proinflammatory mediators. The current trial was planned to evaluate effect of propofol versus isoflurane anesthesia on alveolar and systemic immune modulation during thoracic surgery.
Methods. Fifty adult patients undergoing open thoracic surgery were randomly assigned to receive propofol
(n = 25) or isoflurane
(n = 25) anesthesia. The primary outcome measures included alveolar and plasma concentrations of interleukin-8(IL-8) and tumour necrosis factor-α (TNF-α), whereas secondary outcome measures were alveolar and plasma concentrations of malondialdehyde (MDA), superoxide dismutase (SOD), and changes in alveolar albumin concentrations and cell numbers.
Results. Alveolar and plasma concentrations of IL-8 and TNF-α were significantly lower in the isoflurane group, whereas alveolar and plasma concentrations of MDA were significantly lower in the propofol group. Alveolar and plasma SOD levels increased significantly in the propofol group whereas they showed no significant change in the isoflurane group. Furthermore, the isoflurane group patients developed significantly lower alveolar albumin concentrations and cell numbers.
Conclusion. Isoflurane decreased the inflammatory response associated with OLV during thoracic surgery and may be preferable over propofol in patients with expected high levels of proinflammatory cytokines like cancer patients.

Partial Text

One-lung ventilation (OLV) during thoracic surgery may trigger alveolar cell damage and release of proinflammatory mediators that might lead to lung injury and infection in the postoperative period [1]. A series of clinical and experimental studies on mechanical ventilation reported alteration of alveolar and systemic immunity during surgery and anesthesia [2–4]. Different factors have been implicated that include preoperative smoking or drugs, degree of surgical trauma, preexisting lung or systemic diseases, in addition to type and duration of anesthesia [5, 6].

The current study is a prospective, randomized, double-blinded study done on 50 adult patients ASA I-III undergoing elective open thoracic surgery using one-lung ventilation. A written informed consent was obtained from the patients, and institutional review board approval was obtained. All patients were thoroughly evaluated and investigated to ensure fitness for surgery. ECG, echocardiography, arterial blood gases, and chest CAT scanning were performed for all patients. Exclusion criteria included significant lung diseases {forced expiratory volume in 1 s (FEV1) or vital capacity (VC) < 50% of the predicted values}, heart failure or mean pulmonary artery pressure (MPAP) > 30 mmHg, coagulation disorders or a history of preoperative immuno-suppressant medications. All the operations were performed by the same surgical team. Epidural analgesia was done before induction of anesthesia at the T4–T7 level by inserting an epidural catheter (Braun perifix 18 ba and a microporous filter).

With a 2-sided type I error of 5% and study power at 80%, a mean sample size of 25 patients in each group was found enough to detect differences in alveolar and plasma cytokine concentrations between propofol and isoflurane anesthesia according to a previous study [10]. Continuous variables were reported as mean (standard deviation) and categorical variables were expressed as percentages. Statistical analyses were performed using Statistica for Windows version 10.0 software. The Kolmogorov-Smirnov test was used to verify normal distribution of data. Distribution of residuals testing was performed to confirm that ANOVA was appropriate to our data. Data were analyzed on an intention to treat basis using two-way analysis of variance (ANOVA) for repeated measures. This was followed by Student-Newman-Keuls test, if a difference between groups had been detected. Changes over time in nonnormally distributed data sets were analyzed by Friedman repeated measures ANOVA on ranks. P < 0.05 was considered statistically significant. Both groups were comparable regarding the patients, demographic and operative data (Table 1). The current study has demonstrated that OLV during thoracic surgery induced alveolar and systemic inflammatory reaction. This immune reaction was less in patients exposed to isoflurane anesthesia when compared to propofol anesthesia as indicated by lower alveolar and plasma concentrations of IL-8 and TNF-α. Furthermore, alveolar albumin concentrations and cell numbers were less in patients who received isoflurane anesthesia. However, MDA was higher and SOD was less in patients exposed to isoflurane. Anesthesia, surgery, and OLV induce an inflammatory response in alveolar macrophages that lead to release of proinflammatory cytokines into alveoli and systemic circulation [13]. These cytokines have various actions that include immune modulations and control of tissue infection, injury, and healing [14]. Controlled release of IL-8, TNF-α play an important role in fighting against infection; however, the uncontrolled release of these cytokines triggers massive influx of neutrophils and granulocytes with subsequent lung injury and dysfunction [15]. MDA is an indicator of lipid peroxidation, whereas SOD is an antioxidant enzyme that helps in scavenging free radicals which play a role in tissue injury [16].   Source: