Anaesthetics and immune function

Effects of general anesthesia on airway immune cell function in an equine in vivo model

OBJECTIVE

Complications from general anesthesia, including pneumonia and decreased wound healing, are influenced by changes in immune cell function secondary to sedatives and anesthetics. It was hypothesized that immune cell function would be depressed in the early postanesthetic period. The objective was to investigate airway immune cell function before and after a general anesthetic episode in an equine in vivo model using ex vivo cell stimulations with lipopolysaccharide (LPS) for assessment of immune function.

STUDY DESIGN

Prospective experimental study.

ANIMALS

Six healthy, adult, institution-owned horses.

METHODS

Each horse underwent a bronchoalveolar lavage (BAL) 3 days before and immediately after a 2 hour general anesthetic. The BAL fluid was examined for cytology, total nucleated cell count and isolation of immune cells. Airway immune cells were treated with LPS or media (control) for 6 hours and supernatant was analyzed via a commercially available immunoassay for cytokines [tumor necrosis factor alpha (TNFα), interleukin (IL)-1β, IL-6, interferon gamma (IFNγ) and CXC motif chemokine ligand 8 (CXCL8)]. Data were compared using t-tests and Mann-Whitney tests.

RESULTS

Before anesthesia (baseline), LPS stimulation induced a significant increase in all cytokines of interest, except CXCL8, versus control samples. Unstimulated cells, after an anesthetic episode, had a significant 1.8-fold increase in IL-1β (p = 0.029), and a significant decrease in IL-6 and TNFα (p = 0.028 and 0.033, respectively) versus baseline. Following anesthesia, stimulated cells had a significant decrease in IL-6 and TNFα (p = 0.037 and 0.042, respectively) versus baseline.

CONCLUSIONS AND CLINICAL RELEVANCE

This study supports the use of an equine in vivo model to assess airway immune cell function in relation to general anesthetic use.

Effect of Sevoflurane on the Proliferation of A549 Lung Cancer Cells

Background and Objectives: Sevoflurane has opposing effects on cancer progression, depending on its concentration and the cancer type. This study investigated the effects of sevoflurane on the proliferation of A549 lung cancer cells. Materials and Methods: In vitro, the number of A549 cells exposed to different concentrations of sevoflurane was counted. The size and weight of tumors from a xenograft mouse model exposed to air or sevoflurane were measured in vivo experiments. Additionally, hematoxylin and eosin staining and immunohistochemical detection of Ki-67 in the harvested tumor tissues were performed. Results: A total of 72 culture dishes were used and 24 dishes were assigned to each group: Air group; 2% Sevo group (air + 2% sevoflurane); and 4% Sevo group (air + 4% sevoflurane). The number of A549 cells in the 2% Sevo group was less than that in the Air and 4% Sevo groups (Air: 7.9 ± 0.5; 0.5, 2% Sevo: 6.8 ± 0.4, 4% Sevo: 8.1 ± 0.3; p = 0.000). The tumor size was not significantly different between the two groups (Air: 1.5 ± 0.7, 2% Sevo: 2.4 ± 1.9; p = 0.380). Conclusions: The in vitro data showed that sevoflurane inhibited the proliferation of A549 lung cancer cells in a concentration-specific manner. However, the in vivo data showed no correlation between sevoflurane exposure and A549 cell proliferation. Thus, further research is required to understand fully the effects of sevoflurane on cancer progression and to reconcile differences between the in vitro and in vivo experimental results.

Cortisol secretory patterns in deep and moderate neuromuscular blockades in laparoscopic surgery under total intravenous anesthesia: A prospective, single-blinded, randomized controlled trial

BACKGROUND

Neuroendocrine stress response induces physiological changes depending on the type of surgery and anesthesia. Although the optimal depth of neuromuscular blockade for reducing this response remains unknown, deep neuromuscular blockade is known to improve the surgical environment. Therefore, we hypothesized that a patient's stress response would be lower in surgical procedures under deep neuromuscular blockade than under moderate neuromuscular blockade.

METHODS

This prospective, randomized, single-blind study enrolled 72 patients who underwent laparoscopic gynecological surgery under general anesthesia and were assigned to group D (deep blockade: target train-of-four 0 and posttetanic count ≥ 1) or group M (moderate blockade: target train-of-four count 1-3). The primary endpoints were changing patterns in cortisol and adrenocorticotrophic hormone levels; the secondary endpoints were patient outcomes, such as hemodynamic variables, serum glucose level, postoperative pain in the postanesthesia care unit, and hospital stay.

RESULTS

The baseline characteristics were comparable between the 67 patients included in the 2 groups (34 in group M and 33 in group D). Cortisol and adrenocorticotrophic hormone levels increased perioperatively in both groups but without significant intergroup differences. Serum glucose level increased perioperatively and decreased postoperatively, but without a significant intergroup difference. Postoperative pain, fentanyl requirement in the postanesthesia care unit, and hospital stay were also comparable.

CONCLUSIONS

Compared with moderate neuromuscular blockade, deep neuromuscular blockade improved the surgical environment without significant intergroup differences in the hormonal stress response.

Disturbance of Key Cellular Subproteomes upon Propofol Treatment Is Associated with Increased Permeability of the Blood-Brain Barrier

Background: Propofol is a short-acting anesthetic, which is often used for induction and maintenance of general anesthesia, sedation for mechanically ventilated adults and procedural sedation. Several side effects of propofol are known and a substantial number of patients suffer from post-operative delirium after propofol application. In this study, we analyzed the effect of propofol on the function and protein expression profile on a proteome-wide scale. Methods: We cultured human brain microvascular endothelial cells in absence and presence of propofol and analyzed the permeability of the blood-brain barrier (BBB) by fluorescein passage and protein abundance on a proteome-wide scale by mass spectrometry. Results: Propofol interfered with the function of the blood-brain barrier. This was not due to decreased adhesion of propofol-treated human brain microvascular endothelial cells. The proteomic analysis revealed that some key pathways in these cells were disturbed, such as oxygen metabolism, DNA damage recognition and response to stress. Conclusions: Propofol has strong effects on protein expression which could explain several side effects of propofol.

Early and Long-Term Outcomes after Propofol-and Sevoflurane-Based Anesthesia in Colorectal Cancer Surgery: A Retrospective Study

Background: Propofol is considered to protect against immunosuppression and has lower inflammatory responses in the perioperative period than volatile agents. We evaluated whether the anesthetic agent is associated with cancer outcomes. Methods: We retrospectively reviewed 2616 patients who underwent colorectal cancer surgery under general anesthesia between 2016 and 2018 (follow-up closure: July 2021) at a single institution. Patients received propofol-based total intravenous anesthesia or sevoflurane-based inhalational anesthesia. After propensity score matching, the postoperative neutrophil-lymphocyte ratio (NLR) was compared as primary outcome, and clinical outcomes were evaluated. Results: After 1:2 propensity matching, 717 patients were given propofol anesthesia and 1410 patients were given sevoflurane anesthesia. In the matched cohort, preoperative NLR was not significantly different between propofol and sevoflurane anesthesia (mean (95% CI)2.3 (1.8 to 2.8) and 2.2 (1.9 to 3.2); p = 0.72). NLR was significantly lower in propofol anesthesia at postoperative day two and five (mean difference (95% CI) 0.71 (0.43 to 0.98); p = 0.000 and 0.52 (0.30 to 0.74); p = 0.000). Urinary retention showed a higher incidence after propofol anesthesia (4.9% vs. 2.6%; p = 0.008). Other postoperative complications and overall/recurrence-free survival were not different in the two groups. Discussion: Although propofol anesthesia showed lower postoperative NLR than sevoflurane anesthesia, there was no association with clinical outcomes.

Comparison of General and Spinal Anaesthesia on Systemic Inflammatory Response in Patients Undergoing Total Knee Arthroplasty: A Propensity Score Matching Analysis

Background and Objectives: Some of the postoperative complications following orthopaedic surgeries are associated with a systemic inflammatory response (SIR), which varies depending on the anaesthetic technique. We aimed to compare the effects of general and spinal anaesthesia on the SIR after total knee arthroplasty (TKA), based on C-reactive protein (CRP) levels, the platelet-lymphocyte ratio (PLR), and the neutrophil-lymphocyte ratio (NLR). Materials and Methods: Patients who underwent TKA between January 2014 and December 2018 were included. Electronic medical records of the patients were retrospectively reviewed and analysed. To reduce the impact of potential confounding factors, we performed propensity score matching according to the anaesthetic technique. Results: A total of 1311 TKA cases were analysed. After propensity score matching, the maximal CRP value and changes in CRP levels in the general anaesthesia group were higher than those in the spinal anaesthesia group. However, the maximal NLR and PLR and the changes in NLR and PLR were not different between the two groups. There were no differences in postoperative clinical outcomes. Conclusion: Spinal anaesthesia tended to induce a lower inflammatory response than general anaesthesia when considering CRP levels in patients undergoing TKA. However, the effects of anaesthetic techniques on the overall outcomes were not significant.

Pharmacokinetic, Clinical, and Myeloid Marker Responses to Acepromazine Sedation in Arabian Camels

Sedatives and tranquilizers are important in the control of excited camels during camel transport. This study was conducted to investigate the clinical sedation of camels with acepromazine and its correlation with pharmacokinetics and pharmacodynamics. The sedation score, heart rate, respiration, body temperature, and pharmacokinetics were monitored before and after acepromazine injection, and myeloid marker expression was analyzed using membrane immunofluorescence and flow cytometry. The distribution (t1/2α) and elimination (t1/2β) half-lives were 0.1 and 9.4 h, respectively. The volume of distribution at steady state (Vss) was 20.01 L/kg, and the mean residence time (MRT) was 12.25 h. Sedation started rapidly within 10 min followed by persistent low-medium sedation for 2 h with an average sedation score of 1.2 ± 0.61, which might be associated with a slow elimination phase and prolonged MRT. Compared to horses, camels showed a lower clearance rate, higher volume of distribution, and higher elimination half-life. Slight changes in body temperature and heart and respiratory rate, as well as a lower hematocrit and changes in blood cell composition, suggest the careful application of acepromazine in animals with abnormal blood parameters or poor vital conditions.

Efficacy of ultrasound-guided Transversus Abdominis Plane (TAP) block in inguinal hernia surgery and the immunomodulatory effects of proinflammatory cytokines: prospective, randomized, placebo-controlled study

Background

Tumor Necrosis Factor-α (TNF-α) and Interleukin-1β (IL-1β) are among the cytokines released secondary to the surgical stress response. The objective of this study was to investigate the effect of a Transversus Abdominis Plane (TAP) block on postoperative pain and its immunomodulatory activity through proinflammatory cytokines.

Methods

TAP (study group; n = 40) or p-TAP (placebo group; n = 40). Patients in the TAP group underwent an Ultrasound (US) guided unilateral TAP block using 20-cc 0.5% bupivacaine solution. Patients in the p-TAP group underwent a sham block using 20-cc isotonic solution. The TNF-α and IL-1β levels were measured three times at preoperative hour-0 and postoperative hours 4 and 24. Visual Analog Scale (VAS) scores were recorded at 0-hours, 30-minutes, 4-hours, and 24-hours. Analgesic use within the first 24-hours following surgery was monitored.

Results

The postoperative VAS score was decreased in the TAP group at all time points (0, 4, and 24 hours), and the differences between groups were statistically significant (p <  0.001 for all comparisons). In the TAP group, the TNF-α and IL-1β levels at 4 and 24 hours post operation were significantly lower than the preoperative levels (p <  0.001 for all comparisons).

Conclusion

The TAP block for pre-emptive analgesia enabled effective hemodynamic control during the intraoperative period, provided effective pain control in the postoperative period, and decreased inflammation and surgical stress due to the decreased levels of the proinflammatory cytokines TNF-α and IL-1β in the first postoperative 24 hours, indicating immunomodulatory effect.

Urinary neopterin and total neopterin measurements allow monitoring of oxidative stress and inflammation levels of knee and hip arthroplasty patients

Knee and hip arthroplasty are common surgeries within an aging population. Some data has suggested that knee arthroplasty is more traumatic to the body than hip arthroplasty due to the increased complexity and load bearing nature of the joint. Here, we compare the stress of the two surgeries by measuring urinary neopterin and total neopterin as biomarkers of oxidative stress and inflammation. Urinary neopterin and total neopterin (neopterin + 7,8-dihydroneopterin) levels were analysed in 28 knee and 22 hip arthroplasty patients pre- and post-operatively to determine oxidative stress and inflammation levels. Total neopterin was 31.1% higher with knee arthroplasty (p<0.05). Urinary neopterin was 32.8% higher in the knee arthroplasty group versus hips. The increase in neopterin and total neopterin following a post-surgical decrease in levels was significant in both groups. Levels of neopterin and total neopterin were varied between patients, but all increased following surgery and subsided by day 28. The increased levels of urinary neopterin and total neopterin from knee arthroplasty indicate that knee osteoarthritis and arthroplasty is a more significant trauma to the body than hip osteoarthritis and arthroplasty surgery. This is also shown by faster inflammatory resolution following hip arthroplasty.

Immunomodulators in anesthesia

PURPOSE OF REVIEW

Anesthetics are known to have immunomodulatory effects. These can be detrimental, inducing immunosuppression and facilitating the development of opportunistic infections, especially when used at high doses, for prolonged periods, or in patients with preexisting immune deficiency; or beneficial, modulating the inflammatory response, particularly in critical illness and systemic hyperinflammatory states.

RECENT FINDINGS

Anesthetics can have microbicidal properties, and both anti- and pro-inflammatory effects. They can act directly on immune cells as well as modulate immunity through indirect pathways, acting on the neuroimmune stress response, and have recently been described to interact with the gut microbiota.

SUMMARY

Anesthesiologists should take into consideration the immunomodulatory properties of anesthetic agents in addition to their hemodynamic, neuroprotective, and other impacts. In future, patient stratification according to the perioperative assessment of serum biomarkers associated with postoperative complications may be used to guide anesthetic agent selection based on their immunomodulatory properties.

Knee replacement surgery significantly elevates the urinary inflammatory biomarkers neopterin and 7,8-dihydroneopterin

CONTEXT

Knee arthroplasty surgery is significant trauma, leading to an activated immune system causing inflammation and oxidative stress. Many current biomarkers are invasive, costly, and often slow to analyse, limiting their use for rapid inflammatory measurements.

OBJECTIVES

We have examined the use of urinary neopterin and total neopterin in knee arthroplasty patients to non-invasively measure oxidative stress and inflammation from immune system activation. We aim to validate the use of these biomarkers for quick, cost effective and predictive measurements of post-surgical inflammation assessment.

METHODOLOGY

19 Knee arthroplasty patients were analysed pre-operatively and for a defined post-operative period to determine the urinary levels of neopterin and total neopterin (neopterin +7,8-dihydroneopterin) using high performance liquid chromatography with fluorescence detection. These results were then compared to a control group of 20 participants with normal knee function.

RESULTS

7,8-Dihydroneopterin was stable in urine over 12 h when refrigerated. Knee arthritis was associated with an increase in pre-operative neopterin (oxidative stress) and total neopterin (inflammation). The subsequent arthroplasty surgery generated a significant increase neopterin and total neopterin. Both biomarkers were reduced immediately post-operatively, before becoming elevated on the following days. There was no clear evidence of an association between initial neopterin and total neopterin levels and a patient's level of inflammation during in-hospital recovery.

CONCLUSIONS

The stability of 7,8-dihydroneopterin in urine allows for its use as an inflammatory marker. Urinary neopterin and total neopterin provided a fast, non-invasive, and simple measure of oxidative stress and inflammation after knee arthroplasty.

Effect of Propofol on breast Cancer cell, the immune system, and patient outcome

Breast cancer is the second leading cause of cancer death in women. Surgery is the first line of treatment for breast cancer. Retrospective clinical studies suggest that the type of anesthesia administered during oncological surgery may influence patient outcome. Propofol, the widely used intravenous anesthetic agent, may lead to better outcomes compared to volatile anesthetics. Here we review the literature on the effect of propofol in breast cancer cells, the immune system, pain management, and patient outcomes. Evidence from the study of breast cancer cell lines suggests that high concentrations of propofol have both anti-tumor and pro-tumor effects. Propofol and volatile anesthetics have different effects on the immune system. Propofol has also been shown to reduce the development and severity of acute and chronic pain following surgery. Although a retrospective study that included many types of cancer indicated that propofol increases the long-term survival of patients following surgery, the evidence for this in breast cancer is weak. It has been shown that Propofol combined with paravertebral block led to change of serum composition that affects the breast cancer cell behaviors and natural killer cell activity. Prospective studies are in progress and will be finished within 5 years. The existing evidence is not sufficient to warrant changes to current anesthetic management. Further research is needed to clarify the mechanisms by which propofol affects cancer cells and the immune system.

Anti-inflammatory properties of anesthetic agents

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2017. Other selected articles can be found online at http://ccforum.com/series/annualupdate2017. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Relationship between anesthesia and postoperative endophthalmitis: A retrospective study

Previous study showed that patients under general anesthesia (GA) had nasopharyngeal secretions on the face at the end of ocular surgery, especially in propofol-based total intravenous anesthesia (TIVA), it might induce postoperative endophthalmitis. Therefore, we conducted a retrospective study to compare the incidence of endophthalmitis after ocular surgery under topical, inhalation anesthesia, and propofol-based TIVA in our medical center from 2011 to 2015.A total of 21,032 patients were included, and we evaluated epidemiologic factors, systemic diseases, other ocular pathologic characteristics, complications during the surgery, technique of ocular surgery, method of antibiotic prophylaxis, vitreous culture, and vision outcome in these patients.Fifteen endophthalmitis cases among 21,032 operations reported, equaling an incidence of 0.071%. The incidence rates under topical, inhalation anesthesia, and propofol-based TIVA were 0.083%, 0.039%, and 0%, respectively (P = 0.39). Moreover, the risk of endophthalmitis under GA (0.024%) was significantly lower than topical anesthesia (0.083%) (P < 0.001). We also found that elder was the risk factor for endophthalmitis following ocular surgery.In conclusion, propofol-based TIVA or inhalation anesthesia did not increase the risk of endophthalmitis after ocular surgery. Thus, GA was not a risk factor for postoperative endophthalmitis. By contrast, elder was the risk factor for postoperative endophthalmitis.

Changes in the first postoperative night bispectral index of patients after thyroidectomy with different types of primary anesthetic management: a randomized controlled trial

Despite major advances in anesthesia management and developments in anesthetic agents, postoperative sleep disturbances remain dissatisfactory for many patients. We hypothesized that propofol might have a subtle influence on sleep after thyroidectomy compared to sevoflurane. A randomized, single-blinded, controlled trial was conducted at the First Hospital of China Medical University from October 2014 to October 2015. One hundred and twenty-four patients undergoing thyroidectomy were enrolled and received sevoflurane (sevoflurane group) or propofol (propofol group) as anesthesia maintenance. Major assessments were made during the operation (different types of anesthetic management) and on the first postoperative night (sleep status). The primary outcome was postoperative sleep status, measured by the BIS-Vista monitor on the first night after surgery between propofol and sevoflurane groups. A total of 105 patients (79 women, 26 men; mean age 49 years; range 18-65 years) were included in the final study sample. All patients in both groups showed one of the five sleep patterns classified by this trial. The BIS-area under the curve was decreased, the sleep efficiency index was significantly increased, and the durations of postoperative sleep and sleep stage N3 were increased by 110.5 and 36.5 min per patient, respectively, in the propofol compared to the sevoflurane group. Propofol might preserve sleep time immediately after thyroidectomy. Clinical Trials.gov identifier: NCT 02146976.

Comparing the Effects of Isoflurane-Sufentanil Anesthesia and Propofol-Sufentanil Anesthesia on Serum Cortisol Levels in Open Heart Surgery with Cardiopulmonary Bypass

Background

Major surgeries such as open-heart surgery with cardiopulmonary bypass are associated with a complexity of stress response leading to post-operative complications. Studies have confirmed that anesthesia can mitigate the surgically induced stress response.

Objectives

The aim of this study was to compare the effects of propofol and isoflurane, both supplemented with Sufentanil, on the stress response in coronary artery bypass graft surgery with cardiopulmonary bypass, using cortisol as a biochemical marker.

Methods

This double-blind randomized clinical trial was conducted on 72 patients who underwent coronary artery bypass grafting (CABG) with cardiopulmonary bypass meeting the inclusion criteria. The subjects were randomly divided into two groups of isoflurane (n = 36) and propofol (n = 36) both supplemented with sufentanil. Serum cortisol levels were measured and compared between the groups; 30 minutes before the surgery (T0), at the end of the cardiopulmonary bypass (T1), and 24 hours after the surgery (T2).

Results

Compared to the baseline (T0), at the end of cardiopulmonary bypass (T1), both groups demonstrated a decrease in plasma cortisol levels with no statistical significant difference (P = 0.4). At T2 measuring time point, the level of plasma cortisol significantly increased in both groups (P = 0.02), however this increase was less in the Isoflurane group.

Conclusions

In CABG with cardiopulmonary bypass, using plasma cortisol level as a measure, Isoflurane-Sufentanil significantly reduces the stress response to the surgery, when compared to propofol-Sufentanil.

Modulation of Dendritic Cell Activation and Subsequent Th1 Cell Polarization by Lidocaine

Dendritic cells play an essential role in bridging innate and adaptive immunity by recognizing cellular stress including pathogen- and damage-associated molecular patterns and by shaping the types of antigen-specific T cell immunity. Although lidocaine is widely used in clinical settings that trigger cellular stress, it remains unclear whether such treatment impacts the activation of innate immune cells and subsequent differentiation of T cells. Here we showed that lidocaine inhibited the production of IL–6, TNFα and IL–12 from dendritic cells in response to toll-like receptor ligands including lipopolysaccharide, poly(I:C) and R837 in a dose-dependent manner. Notably, the differentiation of Th1 cells was significantly suppressed by the addition of lidocaine while the same treatment had little effect on the differentiation of Th17, Th2 and regulatory T cells in vitro. Moreover, lidocaine suppressed the ovalbumin-specific Th1 cell responses in vivo induced by the adoptive transfer of ovalbumin-pulsed dendritic cells. These results demonstrate that lidocaine inhibits the activation of dendritic cells in response to toll-like receptor signals and subsequently suppresses the differentiation of Th1 cell responses.

Anesthesia, surgical stress, and "long-term" outcomes

An increasing body of evidence shows that the choice of anesthetic can strongly influence more than simply the quality of anesthesia. Regional and general anesthesia have often been compared to ascertain whether one provides benefits through dampening the stress response or harms by accelerating cancer progression. Regional anesthesia offers considerable advantages, by suppressing cortisol and catecholamine levels and reducing muscle breakdown postoperatively. It also has less immunosuppressive effect and potentially reduces the proinflammatory cytokine response. As such, vital organ functions (e.g., brain and kidney) may be better preserved with regional anesthetics, however, further study is needed. Volatile general anesthetics appear to promote cancer malignancy in comparison to regional and intravenous general anesthetics, and reduce the body's ability to act against cancer cells by suppression of natural killer cell activity. There is not sufficient evidence to support an alteration of current clinical practice, however, further research into this area is warranted due to the potential implications elicited by current studies.

Effect of premedication and other factors on the occurrence of acute transfusion reactions in dogs

OBJECTIVE

To evaluate the effect of premedication on transfusion reactions (TRs) within 24 hours after blood product transfusions in dogs.

DESIGN

Retrospective study between 2008 and 2011.

SETTING

Private veterinary referral hospital.

ANIMALS

Nine hundred and thirty-five transfusion events in 558 dogs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records of dogs receiving blood product transfusions were reviewed. Information collected included signalment, weight, transfusion product type, reason for transfusion, first or subsequent transfusion, whether an acute reaction occurred, type of reaction, whether the reaction was treated, premedication prior to the transfusion and the premedication used, other medications the animal was given, whether the animal had an immune-mediated process, and whether the transfusion was administered in the perioperative period. A total of 144 (15%) acute TRs were documented in 136 dogs. The most common TRs were fever alone (77/144 [53%]) and vomiting alone (26/144 [18%]). Six dogs died due to the TR (4%). TR was not associated with age (P = 0.257), sex (P = 0.754), weight (P = 0.829), or premedication (P = 0.312). The type of blood product transfused (P < 0.001) was significantly associated with TRs, with packed RBCs most likely associated with a TR, and plasma least likely. Immune disease (P = 0.015) was significantly associated with occurrence of a TR. Significantly fewer reactions were documented following transfusions given in the perioperative period (P = 0.023).

CONCLUSIONS

While most TRs were mild, there were some serious reactions observed including hemolysis, dyspnea, and 6 deaths. Immune-mediated disease was associated with development of a TR, while transfusion during the perioperative period was associated with lower likelihood of reaction. Packed RBC transfusions were associated with development of acute TRs. Overall occurrence of TR was not significantly altered with premedication; however, when evaluated alone, antihistamines decreased the incidence of acute allergic reactions.

The Effects of Different Anaesthetic Techniques on Surgical Stress Response During Inguinal Hernia Operations

OBJECTIVE

The aim of this study is to compare the effects of 3 different kinds of anaesthesia on stress response induced by surgery.

METHODS

Sixty patients aged between 25-70 American Society of Anesthesiologists (ASA) I-II group to undergo inguinal herniography were included in this study. Patients were randomly divided into 3 groups of 20. Group 1 received general anaesthesia with sevoflurane/air/remifentanil, patients in Group 2 received total intravenous anaesthesia (TIVA) with propofol/air/remifentanil and Group 3 received spinal anaesthesia induced by hyperbaric bupivacaine, adjoined by remifentanil sedation. Mean arterial pressure (MAP), heart rate and SpO2 values were recorded preoperatively, intraoperatively and postoperatively at certain periods. Cortisol, leptin and glucose levels were preoperatively detected. Intervals were as; 15 minutes prior to the induction of anaesthesia, at intraoperative first hour and at the postoperative third and twenty-forth hours.

RESULTS

MAP and heart rate values were similar in the inhalational anaesthesia and TIVA groups but relatively higher in the spinal anaesthesia group. Blood glucose levels were elevated, insulin levels were decreased in all groups, at the intraoperative first hour. Biphasic variation in blood leptin levels was observed in all groups, as the levels were lower than the preoperative control values at the intraoperative first and postoperative third hours and significantly higher at the postoperative twenty-forth hour. There was a significant decrease in cortisol level percentage change in the TIVA group at the intraoperative 1st hour, increasing in the other groups.

CONCLUSION

We concluded that TIVA supresses the stress response induced by surgery better by lowering cortisol levels, leading to a lower increase in blood glucose levels and a lower decrease in blood insulin levels when compared to others. Furthermore, leptin levels were increased at the postoperative twenty-forth hour. The lower increase at the postoperative twenty-forth hour in the TIVA group can be correlated with the anaesthetic agent.

Does pharmacotherapy influence the inflammatory responses during cardiopulmonary bypass in children?

Cardiopulmonary bypass (CPB) induces a systemic inflammatory response syndrome (SIRS) by factors such as contact of the blood with the foreign surface of the extracorporeal circuit, hypothermia, reduction of pulmonary blood flow during CPB and endotoxemia. SIRS is maintained in the postoperative phase, co-occurring with a counter anti-inflammatory response syndrome. Research on the effects of drugs administered before the surgery, especially in the induction phase of anesthesia, as well as drugs used during extracorporeal circulation, has revealed that they greatly influence these postoperative inflammatory responses. A better understanding of these processes may not only improve postoperative recovery but also enable tailor-made pharmacotherapy, with both health and economic benefits. In this review, we describe the pathophysiology of SIRS and counter anti-inflammatory response syndrome in the light of CPB in children and the influence of drugs used on these syndromes.

[Plasma levels of interleukin-10 and nitric oxide in response to two different desflurane anesthesia flow rates]

OBJECTIVE

This study investigated interleukin-10 and nitric oxide plasma levels following surgery to determine whether there is a correlation between these two variables and if different desflurane anesthesia flow rates influence nitric oxide and interleukin-10 concentrations in circulation.

MATERIALS AND METHODS

Forty patients between 18 and 70 years and ASA I-II physical status who were scheduled to undergo thyroidectomy were enrolled in the study.

INTERVENTIONS

Patients were allocated into two groups to receive two different desflurane anesthesia flow rates: high flow (Group HF) and low flow (Group LF).

MEASUREMENTS

Blood samples were drawn at the beginning (t0) and end (t1) of the operation and after 24h (t2). Plasma interleukin-10 and nitric oxide levels were measured using an enzyme-linked-immunosorbent assay and a Griess reagents kit, respectively. Hemodynamic and respiratory parameters were assessed.

RESULTS

There was no statistically significant difference between the two groups with regard to interleukin-10 levels at the times of measurement. Interleukin-10 levels were increased equally in both groups at times t1 and t2 compared with preoperative concentrations. For both groups, nitric oxide circulating concentrations were significantly reduced at times t1 and t2 compared with preoperative concentrations. However, the nitric oxide value was lower for Group HF compared to Group LF at t2. No correlation was found between the IL-10 and nitric oxide levels.

CONCLUSION

Clinical usage of two different flow anesthesia forms with desflurane may increase interleukin-10 levels both in Group HF and Group LF; nitric oxide levels circulating concentrations were significantly reduced at times t1 and t2 compared with preoperative concentrations; however, at 24h postoperatively they were higher in Group LF compared to Group HF. No correlation was detected between interleukin-10 and nitric oxide levels.

Effects of preemptive intravenous lornoxicam on the analgesic efficacy of epidural morphine and expression of chemokines in women undergoing hysterectomy

BACKGROUND

It is believed that preemptive IV lornoxicam treatment can reduce the consumption of other analgesics, improve analgesic efficacy, and ameliorate immune function during patient-controlled IV analgesia. However, the effects of preemptive IV lornoxicam treatment on the analgesic efficacy of patient-controlled epidural analgesia (PCEA) with morphine and on chemokine expression remain unknown.

OBJECTIVE

The aim of this prospective, randomized, controlled study was to observe the effects of preemptive IV lornoxicam treatment on the analgesic efficacy of PCEA with morphine and on the expression of monocyte chemotactic protein-1 (MCP-1) and stromal cell-derived factor-1α (SDF-1α) in women undergoing hysterectomy.

METHODS

Patients undergoing elective hysterectomy with combined spinal and epidural anesthesia were randomized to 1 of 3 groups to receive IV lornoxicam 8 mg before anesthesia (group 1), lornoxicam 16-mg injection before anesthesia (group 2), or isotonic saline (control) before anesthesia. PCEA was used to treat postoperative pain, and a visual analog scale (VAS) and the Bruggemann Comfort Scale (BCS) were used to evaluate analgesic efficacy. Morphine consumption was recorded. To measure plasma concentrations of MCP-1 and SDF-1α via enzyme-linked immunosorbent assay, venous blood samples were obtained from patients at 4 separate times: before anesthesia (baseline); 0 (immediately after anesthesia administration); and 24 and 48 hours after surgery.

RESULTS

Forty-five patients (mean [SD] age, 41 [5] years; mean [SD] weight, 54 [6] kg) undergoing elective hysterectomy were included in the study. There were no significant differences in VAS scores, BCS scores, or morphine consumption between the 3 groups. Compared with baseline values, MCP-1 and SDF-1α concentrations were increased significantly immediately after surgery in all 3 groups (all, P < 0.01) and returned to near-baseline values at 24 hours postsurgery in groups 1 and 2, and by 48 hours postsurgery in the control group. MCP-1 and SDF-1α concentrations in groups 1 and 2 were significantly lower than those in the control group immediately (all, P < 0.01) and 24 hours postsurgery (all, P < 0.05).

CONCLUSION

Preemptive IV lornoxicam treatment was associated with attenuation of the plasma concentrations of MCP-1 and SDF-1α immediately after and 24 hours after hysterectomy and was associated with more rapid resolution to near-baseline concentrations of both cytokines in these patients compared with controls; however, it was not associated with significantly reducing epidural morphine consumption.

Plasma levels of interleukin-10 and nitric oxide in response to two different desflurane anesthesia flow rates

OBJECTIVE

This study investigated interleukin-10 and nitric oxide plasma levels following surgery to determine whether there is a correlation between these two variables and if different desflurane anesthesia flow rates influence nitric oxide and interleukin-10 concentrations in circulation.

MATERIALS AND METHODS

Forty patients between 18 and 70 years and ASA I-II physical status who were scheduled to undergo thyroidectomy were enrolled in the study.

INTERVENTIONS

Patients were allocated into two groups to receive two different desflurane anesthesia flow rates: high flow (Group HF) and low flow (Group LF).

MEASUREMENTS

Blood samples were drawn at the beginning (t0) and end (t1) of the operation and after 24h (t2). Plasma interleukin-10 and nitric oxide levels were measured using an enzyme-linked-immunosorbent assay and a Griess reagents kit, respectively. Hemodynamic and respiratory parameters were assessed.

RESULTS

There was no statistically significant difference between the two groups with regard to interleukin-10 levels at the times of measurement. Interleukin-10 levels were increased equally in both groups at times t1 and t2 compared with preoperative concentrations. For both groups, nitric oxide circulating concentrations were significantly reduced at times t1 and t2 compared with preoperative concentrations. However, the nitric oxide value was lower for Group HF compared to Group LF at t2. No correlation was found between the IL-10 and nitric oxide levels.

CONCLUSION

Clinical usage of two different flow anesthesia forms with desflurane may increase interleukin-10 levels both in Group HF and Group LF; nitric oxide levels circulating concentrations were significantly reduced at times t1 and t2 compared with preoperative concentrations; however, at 24h postoperatively they were higher in Group LF compared to Group HF. No correlation was detected between interleukin-10 and nitric oxide levels.

Inhibitory effect of midazolam on MMP-9, MMP-1 and MMP-13 expression in PMA-stimulated human chondrocytes via recovery of NF-κB signaling

INTRODUCTION

Midazolam, a benzodiazepine, has a hypnotic effect and is widely used as an intravenous sedative. Past studies have clearly established that midazolam has beneficial effects in attenuating ischemia-reperfusion injury more than other currently used sedative drugs. However, the role of midazolam on chondroprotection via inhibition of matrix metalloproteinases (MMPs) is warrant investigation. The aim of this study was to examine the mechanisms of action of midazolam on MMP expression via nuclear factor κB (NF-κB) signaling in activated chondrosarcoma cells maintained in vitro.

MATERIAL AND METHODS

Chondrocytes, SW1353 cells, were stimulated with phorbol 12-myristate 13-acetate (PMA) in the absence or presence of various concentrations of midazolam (5-20 µM). Release of MMP-9 into the culture media was determined by gelatin zymography. The expressions of MMP-1, MMP-9 and MMP-13, phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinases and degradation of IκB-α were determined by western blotting assay.

RESULTS

Midazolam significantly down-regulated PMA-induced MMP-9 protein expression at concentrations of 5, 10 and 20 µM, the values were 1.95 ±0.09 (p < 0.01), 1.71 ±0.12 (p < 0.01) and 1.35 ±0.20 (p < 0.001), respectively. At concentrations of 5, 10 and 20 µM, it was significantly inhibited the PMA-induced expressions of MMP-1 (2.27 ±0.10, 1.98 ±0.11 and 1.56 ±0.15; p < 0.001) and MMP-13 (0.89 ±0.04, 0.81 ±0.07, and 0.74 ±0.09; p < 0.001), respectively. Midazolam at concentrations of 10 and 20 µM for 15 min significantly reversed the rate of degradation (0.895 ±0.051; p < 0.05 and 0.926 ±0.060; p < 0.01, respectively) of IκB-α in PMA-chondrocyte cells. In addition, this sedative drug inhibited PMA-induced levels of phos-ERK (1.243 ±0.12, 1.108 ±0.16 and 0.903 ±0.19, respectively) and phos-p38 (1.146 ±0.10, 1.063 ±0.13 and 0.946 ±0.18, at concentrations of (5, 10 and 20 µM), respectively.

CONCLUSIONS

These results are important for understanding the mechanism of midazolam in inhibiting PMA-induced MMP expression through the signaling pathways of either NF-κB or ERK/p38 MAPKs down-regulation.

Sedation & immunomodulation

As the armamentarium for sedation in the critically ill expands, opportunities will develop to modulate the immune responses of patients by way of the direct immune and neural-immune interactions of the sedatives. Control of autonomic activity through the use of appropriate sedation may be critical in this matter. Likewise analgesic-based sedation, with increased opioid dosage, may not prove beneficial in the setting of infection; whether avoidance of morphine in preference for a fentanyl derivative will help is unclear. However, as the immune effects seem dependent on the m receptor, it is improbable that a significant difference would be uncovered. Similarly, the present evidence suggests benzodiazepines are deleterious in infection; further studies are required urgently to evaluate this evidence. As an alternative to benzodiazepine-based sedation, dexmedetomidine has shown a remarkable 70% mortality benefit in a small secondary analysis of septic patients from the MENDS trial. Further powered clinical studies should now be undertaken to investigate the potential benefit of the α2-adrenoceptor agonist in this setting, with comparisons with propofol.

[Nonanalgesic effects of thoracic epidural anesthesia]

Thoracic epidural anesthesia, which has been performed since the 1950s, has progressed from being one analgesic technique among others to its present status as the technique of choice for managing pain after major abdominal and thoracic surgery. In addition to providing effective analgesia, the epidural infusion of local anesthetic agents produces a sympathetic block that offers advantages over other types of pain control, particularly with respect to the cardiovascular, respiratory, and gastrointestinal systems. Thoracic epidural anesthesia provides dynamic pain relief, allowing the patient to resume activity early. It also permits early extubation and is associated with fewer postoperative pulmonary complications, shorter duration of paralytic ileus, and a better response to the stress of anesthesia and surgery. However, meta-analyses have not yet demonstrated that postoperative outcomes are improved. This review describes the nonanalgesic effects of thoracic epidural anesthesia.

The epidemiology of sepsis in general surgery patients

BACKGROUND

Sepsis is increasing in hospitalized patients. Our purpose is to describe its current epidemiology in a general surgery (GS) intensive care unit (ICU) where patients are routinely screened and aggressively treated for sepsis by an established protocol.

METHODS

Our prospective, Institutional Review Board-approved sepsis research database was queried for demographics, biomarkers reflecting organ dysfunction, and mortality. Patients were grouped as sepsis, severe sepsis, or septic shock using refined consensus criteria. Data are compared by analysis of variance, Student's t test, and χ test (p<0.05 significant).

RESULTS

During 24 months ending September 2009, 231 patients (aged 59 years ± 3 years; 43% men) were treated for sepsis. The abdomen was the source of infection in 69% of patients. Several baseline biomarkers of organ dysfunction (BOD) correlated with sepsis severity including lactate, creatinine, international normalized ratio, platelet count, and d-dimer. Direct correlation with mortality was noted with particular baseline BODs including beta natriuretic peptide, international normalized ratio, platelet count, aspartate transaminase, alanine aminotransferase, and total bilirubin. Most patients present with severe sepsis (56%) or septic shock (26%) each with increasing multiple BODs. Septic shock has prohibitive mortality rate (36%), and those who survive septic shock have prolonged ICU stays.

CONCLUSION

In general surgery ICU patients, sepsis is predominantly caused by intra-abdominal infection. Multiple BODs are present in severe sepsis and septic shock but are notably advanced in septic shock. Despite aggressive sepsis screening and treatment, septic shock remains a morbid condition.

Immunomodulation during and after castration under inhalation anaesthetic without genotoxic effects on equine lymphocytes

Genotoxic DNA damage due to inhalation anaesthesia has been demonstrated in human lymphocytes. In order to evaluate anaesthesia-associated changes in cell-mediated immunity on the basis of a potential DNA damage as a health risk in horses, single cell gel electrophoresis and lymphocyte proliferation assay were performed on equine lymphocytes which were obtained before, during and after regular castration under inhalation anaesthetic. No significant lymphocytic DNA damage due to isoflurane anaesthesia was observed, whereas lymphocyte proliferative reactivity and lymphocyte counts decreased significantly (p≤0.05) during and after anaesthesia. The present study thus indicates that the combined anaesthesia does not result in significant DNA damage, which hence cannot be held responsible for the observed changes in the immune response of equine lymphocytes. However, the recognized compromises of immune function ought to be considered especially in immunologically challenged animals.

Postoperative complications in a lamb after major surgery

INTRODUCTION

Anaesthesia in lambs undergoing experimental surgery may develop problems associated with age-related immune incompetency: a postoperative complication in a 3 week old Scottish blackface lamb after spinal surgery is presented. CASE HISTORY AND MANAGEMENT: Both lamb and ewe were in good condition. The ewe was vaccinated against Clostridium perfringens and Clostridium tetani 5 weeks pre-partum. There were no apparent problems with the lamb's intake of colostrum. Pre-anaesthetic medication was intramuscular medetomidine (10 μg kg(-1)). Anaesthesia was induced and maintained with sevoflurane in oxygen. Morphine (0.5 mg kg(-1)), meloxicam (0.6 mg kg(-1)) and ketamine (1 mg kg(-1) followed by 10 μg kg(-1) minute(-1)) were administered intravenously (IV) for perioperative analgesia. Atracurium (0.5 mg kg(-1) IV, followed by 0.17 mg kg(-1) injected when the first twitch of the four, train-of four count was palpated) was used to improve muscle relaxation. The lamb's trachea was intubated and the lungs mechanically ventilated to maintain normocapnia. Intrathecal morphine (0.2 mg kg(-1)), IV meloxicam (0.3 mg kg(-1)) and edrophonium (0.5 mg kg(-1)) were administered before recovery. Operative and initial recovery periods were unremarkable. Three hours after surgery the lamb became depressed. Tachycardia (180-250 beats minute(-1)), tachypnoea (30 breaths minute(-1)), poor peripheral perfusion and cold pelvic limb extremities were present mimicking severe pain, and/or hypovolaemic shock. Analgesics - morphine (total dose 1.3 mg kg(-1)) - and IV fluid therapy boluses - crystalloids (300 mL), colloids (120 mL) and fresh whole blood (60 mL) - failed to ameliorate clinical signs and so the lamb was euthanized 10 hours after surgery. Post-mortem findings supported a possible diagnosis of peracute Clostridium perfringens enterotoxaemia.

CONCLUSION

Clostridium perfringens enterotoxaemia should be considered when clinical signs of severe pain and/or hypovolaemic shock fail to respond to analgesics and fluid resuscitation in lambs after major surgery.

Epidural anesthesia and cancer recurrence rates after radical prostatectomy

PURPOSE

To determine the effect of adjunctive epidural local anesthetic and opioid infusion on disease recurrence following radical prostatectomy for adenocarcinoma under general anesthesia.

METHODS

This article describes a secondary analysis of subjects undergoing radical prostatectomy who had participated previously in a randomized controlled trial evaluating pain control, blood loss, and the need for perioperative allogeneic blood transfusion. The patients were randomly allocated to receive either general anesthesia alone (control group; n = 50) or combined general/epidural anesthesia (study group; n = 49). A long-term follow-up chart review was undertaken to determine clinically evident or biochemical (Prostate Specific Antigen > 0.2 ng x mL(-1)) recurrence of prostate cancer. Comparison by group was undertaken using survival analysis.

RESULTS

Median disease-free survival for the study as a whole was 1644 days, and the longest recorded survival was 3403 days. Biochemical recurrence of prostate cancer was observed in 11/49 study subjects and 17/50 control subjects. There was one death from prostate cancer in each group and a total of five deaths in the study group and six deaths in the control group. The hazard ratio for recurrence in the study group compared with the control group was 1.33 (95% confidence intervals 0.64-2.77; P = 0.44 by log-rank test).

CONCLUSION

No difference was observed between the epidural and control groups in disease-free survival at a median follow-up time of 4.5 years. There is a need for large randomized controlled trials to determine the ability of epidural analgesia to alter disease recurrence rates following radical prostatectomy.

Differential effects of propofol and isoflurane on the activation of T-helper cells in lung cancer patients

It is suggested that activation and differentiation of T-helper cells are required for peri-operative anti-tumor and anti-infection immunity. The present study aimed to evaluate whether propofol stimulates the activation and differentiation of these cells in patients undergoing pulmonary lobectomy for non-small-cell lung cancer. Thirty patients were randomly allocated to receive propofol or isoflurane throughout surgery. The CD4(+)CD28(+) percentage (p < 0.0001) and the ratio of interferon-gamma:interleukin-4 (p = 0.001) all increased with propofol but showed no change with isoflurane. In contrast, cortisol increased with isoflurane (p < 0.0001) but not with propofol over time (p = 0.06). We conclude that propofol promotes activation and differentiation of peripheral T-helper cells.

Pathophysiology of the systemic inflammatory response after major accidental trauma

Background

The purpose of the present study was to describe the pathophysiology of the systemic inflammatory response after major trauma and the timing of final reconstructive surgery.

Methods

An unsystematic review of the medical literature was performed and articles pertaining to the inflammatory response to trauma were obtained. The literature selected was based on the preference and clinical expertise of authors.

Discussion

The inflammatory response consists of hormonal metabolic and immunological components and the extent correlates with the magnitude of the tissue injury. After trauma and uncomplicated surgery a delicate balance between pro- and anti-inflammatory mediators is observed. Trauma patients are, however, often exposed, not only to the trauma, but to several events in the form of initial surgery and later final reconstructive surgery. In this case immune paralysis associated with increased risk of infection might develop. The inflammatory response is normalized 3 weeks following trauma. It has been proposed that the final reconstructive surgery should be postponed until the inflammatory response is normalized. This statement is however not based on clinical trials.

Conclusion

Postponement of final reconstructive surgery until the inflammatory is normalized should be based on prospective randomized trials.

Sedation improves early outcome in severely septic Sprague Dawley rats

INTRODUCTION

Sepsis, a systemic inflammatory response to infective etiologies, has a high mortality rate that is linked both to excess cytokine activity and apoptosis of critical immune cells. Dexmedetomidine has recently been shown to improve outcome in a septic cohort of patients when compared to patients randomized to a benzodiazepine-based sedative regimen. We sought to compare the effects of dexmedetomidine and midazolam, at equi-sedative doses, on inflammation and apoptosis in an animal model of severe sepsis.

METHODS

After central venous access, Sprague Dawley rats underwent cecal ligation and intestinal puncture (CLIP) with an 18 G needle without antibiotic cover and received either saline, or an infusion of comparable volume of saline containing midazolam (0.6 mg.kg-1.h-1) or dexmedetomidine (5 ug.kg-1.h-1) for 8 hours. Following baseline measurements and CLIP, blood was sampled for cytokine measurement (tumour necrosis factor (TNF)-alpha and interleukin (IL)-6; n = 4-6 per group) at 2, 4 and 5 hours, and animal mortality rate (MR) was monitored (n = 10 per group) every 2 hours until 2 hours had elapsed. In addition, spleens were harvested and apoptosis was assessed by immunoblotting (n = 4 per group).

RESULTS

The 24 hour MR in CLIP animals (90%) was significantly reduced by sedative doses of either dexmedetomidine (MR = 20%) or midazolam (MR = 30%). While both sedatives reduced systemic levels of the inflammatory cytokine TNF-alpha (P < 0.05); only dexmedetomidine reduced the IL-6 response to CLIP, though this narrowly missed achieving significance (P = 0.05). Dexmedetomidine reduced splenic caspase-3 expression (P < 0.05), a marker of apoptosis, when compared to either midazolam or saline.

CONCLUSIONS

Sedation with midazolam and dexmedetomidine both improve outcome in polymicrobial severely septic rats. Possible benefits conveyed by one sedative regimen over another may become evident over a more prolonged time-course as both IL-6 and apoptosis were reduced by dexmedetomidine but not midazolam. Further studies are required to evaluate this hypothesis.

Anaesthetic considerations of the HIV-infected patients

PURPOSE OF REVIEW

Human immunodeficiency virus (HIV) infection is one of the major global health problems. Because the advances in treatment of HIV infection increase the patient's survival, anaesthesiologists may care for these patients during their practice. This article highlights HIV infection and anaesthetic implications.

RECENT FINDINGS

HIV infection is a spectrum of disease varying from asymptomatic to multiple organ involvement. Safe anaesthetic management in HIV-infected patients includes understanding basic knowledge of HIV infection, organ involvement, pharmacology and adverse reactions of antiretroviral agents. There are no specific anaesthetic agents and techniques for HIV-infected patients. Issues on central neural blockade and immunological aspects on HIV infection were discussed. Infection control to prevent transmission of infections to and from HIV-infected patients must be strictly conducted.

SUMMARY

Anaesthesia in HIV-infected patients should be individualized and depend on the status of the patient.

Circulating free fatty acids do not contribute to the acute systemic inflammatory response. an experimental study in porcine endotoxaemia

Intensive insulin therapy, aiming for strict normoglycaemia, is associated with increased survival in critically ill patients. Insulin therapy concomitantly reduces plasma-free fatty acids. Recent studies indicate that free fatty acids mediate inflammation. In addition to plasma glucose and free fatty acid-lowering effects, insulin also has anti-inflammatory properties. This study was designed to study the pro-inflammatory effects of two free fatty acid concentrations during acute endotoxaemia and controlled comparable levels of plasma glucose and insulin. Twenty pigs were anaesthetized and mechanically ventilated. Pigs were randomized to two different, constant Intralipid infusion rates, throughout observation. All pigs were administered continuous intravenous infusion of endotoxin and subjected to controlled levels of p-glucose (4.5 mmol/l) and insulin by use of a hyperinsulinaemic euglycaemic clamp. Changes in circulating tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, leucocytes, insulin, glucose, free fatty acids, triglycerides, albumin, blood gases, temperature, and, haemodynamic function were monitored. Immediately following killing, biopsies were taken from heart and kidney. Biopsies were analysed for protein content of TNF-alpha, IL-6, IL-8 and IL-10. Sustained elevated and significantly different plasma levels of free fatty acids were demonstrated between groups (mean free fatty acid concentrations, 1.62 mM versus 0.58 mM, p < 0.0002). Endotoxaemia induced a steep increase in plasma TNF-alpha, IL-6 and leucocytes, however, without differences between the low- and high-free fatty acid groups. Cytokine content in heart and kidney tissue was not modified by free fatty acids. Compared with the response obtained at lower free fatty acid levels, high free fatty acid levels did not exacerbate the inflammatory response to acute endotoxaemia. Our results do not support the role of free fatty acids as a significant pro-inflammatory mediator.