Maximilien Gourdin

The impact of ischaemia-reperfusion on the blood vessel.

Ischaemia significantly affects the cellular homeostasis (sodium and calcium overload, intracellular acidosis, swelling, cytoskeleton injuries, mitochondrial hypercalcaemia and others). If reperfusion of an organ in ischaemia is essential for its viability and its functional recovery, the arrival of blood oxygen will cause a series of lesions; this is known as the phenomenon of ischaemia–reperfusion. Vasomotricity and the endothelial functions are significantly affected by it. Endothelium-dependent vasodilatation is more affected by ischaemia–reperfusion injuries than vasoconstriction and endothelial-independent vasodilatation. Reactive oxygen species and tumour necrosis factor-α seem to play a major role in this perturbation. Reperfusion also induces an important inflammatory response, characterized by a massive production of free radicals and by the activation of the complement and leucocyte neutrophils. A narrow interaction between activated endothelium and neutrophils will result in a significant concentration of neutrophils activated in the interstitium, where they release many oxygen radicals and many kinds of proteases, which destroy cells and extracellular matrix. This transfer of neutrophils from the intravascular bed to the intestitium involves several families of proteins such as selectins (P-selectin and L-selectin), integrines (intercellular adhesion molecule-1) and immunoglobulins (platelet–endothelial cell adhesion molecule-1). Last, oxidative stress, the production of cytokines and the secondary mitochondrial lesions that occur with reperfusion will induce apoptosis on the level of the parenchyma and the vascular structures. According to the stage of the vascular system considered (small arteries, capillaries or postcapillary veins), the repercussions of ischaemia–reperfusion are identical, but the clinical pictures differ. The proinflammatory state induced by reperfusion continues for several days and can affect the patients prognosis.

Deep neuromuscular block improves surgical conditions during laparoscopic hysterectomy: a randomised controlled trial.

BACKGROUND The benefit of inducing deep neuromuscular block to improve laparoscopic surgical conditions is controversial. OBJECTIVE The goal of this study was to determine the depth of neuromuscular block needed to guarantee excellent operating conditions during laparoscopic hysterectomy. DESIGN A randomised controlled trial. SETTING A single-centre study performed between February 2011 and May 2012. PATIENTS One hundred and two women of ASA physical status 1 or 2 gave consent to participate and were allocated randomly to one of two groups. INTERVENTION Under desflurane general anaesthesia, patients in Group S (shallow block), neuromuscular blockade was induced by administration of rocuronium 0.45 mg kg−1 followed by spontaneous recovery or a rescue bolus dose of 5 mg if surgical conditions were unacceptable. In Group D (deep block), neuromuscular block was induced by administration of rocuronium 0.6 mg kg−1 and maintained by bolus doses of 5 mg if the train-of-four count exceeded two, using adductor pollicis electromyography. MAIN OUTCOME MEASURES With a stable pneumoperitoneum (13 mmHg), the surgeon scored the quality of the surgical field every 10 min as excellent (1), good but not optimal (2), poor but acceptable (3) or unacceptable (4). The groups were compared using the Cochran–Armitage trend test. The level of neuromuscular blockade was recorded each time the surgical field score exceeded 1. RESULTS For groups S and D, respectively, the maximum surgical field scores were 1 in 21 and 34 patients, 2 in 11 and 11 patients, 3 in 4 and 5 patients and 4 in 14 and 0 patients. A trend towards higher scores was demonstrated in group S (P < 0.001). Surgical field scores of 2, 3 and 4 occurred only when the train-of-four count was at least 1, 2 and 3, respectively. CONCLUSION Inducing deep neuromuscular block (train-of-four count <1) significantly improved surgical field scores and made it possible to completely prevent unacceptable surgical conditions.

Is Thrombin Time useful for the assessment of dabigatran concentrations? An in vitro and ex vivo study

Is Thrombin Time useful for the assessment of dabigatran concentrations? An in vitro and ex vivo study

Management of Non-Vitamin K Antagonist Oral Anticoagulants in the Perioperative Setting

The field of oral anticoagulation has evolved with the arrival of non-vitamin K antagonist oral anticoagulants (NOACs) including an anti-IIa agent (dabigatran etexilate) and anti-Xa agents (rivaroxaban and apixaban). The main specificities of these drugs are predictable pharmacokinetics and pharmacodynamics but special attention should be paid in the elderly, in case of renal dysfunction and in case of emergency. In addition, their perioperative management is challenging, especially with the absence of specific antidotes. Effectively, periods of interruption before surgery or invasive procedures depend on half-life and keeping a permanent balance between bleeding and thromboembolic risks. In addition, few data regarding the link between plasma concentrations and their effects are provided. Routine laboratory tests are altered by NOACs and quantitative measurements are not widely performed. This paper provides a review on the management of NOACs in the perioperative setting, including the estimation of the bleeding and thrombotic risk, the periods of interruption, the indication of heparin bridging, the usefulness of laboratory tests before surgery or invasive procedure, and the time of resuming. Most data are based on experts opinions.

The Effect of Clonidine, an Alpha-2 Adrenergic Receptor Agonist, on Inflammatory Response and Postischemic Endothelium Function During Early Reperfusion in Healthy Volunteers.

Abstract: Ischemia–reperfusion disturbs endothelial physiology and generates a proinflammatory state. Animal studies showed that clonidine administered prior hypoxia improves posthypoxic endothelial function. To investigate this effect in human, we have assessed the postischemic endothelium function and the proinflammatory state in healthy volunteers with and without clonidine. Seven volunteers were included. Each subject underwent the experimental protocol (15 minutes nondominant forearm ischemia) with and without clonidine. Endothelial function was assessed by flow-mediated dilatation (FMD) in the brachial artery before ischemia (FMDPI), immediately after ischemia (FMDIAI), and 15 minutes after ischemia (FMD15AI). Neutrophil (CD11b/CD18) and platelet (CD42b) activations were measured by flow cytometry during reperfusion in blood samples from ischemic (local) and nonischemic (systemic) forearms. Proinflammatory state was assessed by serum concentration of interleukin (IL)-1&bgr; and -6. Clonidine does not influence baseline FMD (P = 0.118) but improves FMDIAI (P = 0.018) and FMD15AI (P = 0.018). It increases platelet activation in systemic circulation (P = 0.003) during reperfusion but not in local circulation (P = 0.086). Clonidine increases neutrophil activation in local circulation (P = 0.001) but not in systemic circulation (P = 0.642). In local circulation, clonidine decreases IL-6 (P = 0.044) but does not influence IL-1&bgr; (P = 0.113). By contrast, it decreases both IL-6 (P = 0.026) and IL-1&bgr; (P = 0.027) concentrations in systemic circulation. In conclusion, clonidine improves endothelial function and modulates inflammation during reperfusion.

Rapid exclusion of the diagnosis of immune HIT by AcuStar HIT and heparin-induced multiple electrode aggregometry

BACKGROUND Accurate diagnosis of heparin-induced thrombocytopenia (HIT) is essential but remains challenging. We have previously demonstrated, in a retrospective study, the usefulness of the combination of the 4Ts score, AcuStar HIT and heparin-induced multiple electrode aggregometry (HIMEA) with optimized thresholds. OBJECTIVES We aimed at exploring prospectively the performances of our optimized diagnostic algorithm on suspected HIT patients. The secondary objective is to evaluate performances of AcuStar HIT-Ab (PF4-H) in comparison with the clinical outcome. METHODS 116 inpatients with clinically suspected immune HIT were included. Our optimized diagnostic algorithm was applied to each patient. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) of the overall diagnostic strategy as well as AcuStar HIT-Ab (at manufacturers thresholds and at our thresholds) were calculated using clinical diagnosis as the reference. RESULTS Among 116 patients, 2 patients had clinically-diagnosed HIT. These 2 patients were positive on AcuStar HIT-Ab, AcuStar HIT-IgG and HIMEA. Using our optimized algorithm, all patients were correctly diagnosed. AcuStar HIT-Ab at our cut-off (>9.41 U/mL) and at manufacturers cut-off (>1.00 U/mL) showed both a sensitivity of 100.0% and a specificity of 99.1% and 90.4%, respectively. CONCLUSION The combination of the 4Ts score, the HemosIL® AcuStar HIT and HIMEA with optimized thresholds may be useful for the rapid and accurate exclusion of the diagnosis of immune HIT.

Postoperative analgesic effect of transcranial direct current stimulation in lumbar spine surgery: a randomized control trial.

Background:Ultimately, the experience of pain derives from changes in brain excitability. Therefore, modulating the excitability of cortical areas involved in pain processing may become an attractive option in the context of multimodal analgesia during the postoperative period. Repetitive transcranial magnetic stimulation (rTMS) can reduce morphine consumption during the postoperative period after gastric bypass surgery. We tested the potential of another method of noninvasive brain stimulation, transcranial direct current stimulation (tDCS), to reduce morphine consumption or pain perception during the postoperative period. Methods:Fifty-nine ASA I to II patients undergoing lumbar spine surgery were randomized to receive anodal (n=20), cathodal (n=20), or sham (n=19) tDCS in the recovery room in a double-blind manner. Morphine consumption administrated through patient-controlled analgesia (PCA) was the primary outcome; pain perception as measured by visual analog scale was the secondary outcome. Results:There were no statistically significant differences between the 3 groups of patients, either for PCA morphine consumption or for pain scores. Conclusions:Several factors may explain the observed lack of impact of tDCS on PCA morphine consumption and pain perception: the method of brain stimulation (tDCS/rTMS), potential interactions with anesthetic drugs, differences in patients population (gastric bypass surgery/lumbar spine surgery), and the previous experience of pain and chronic consumption of analgesic drugs. Further studies with tDCS should be performed before concluding that tDCS is inefficient for postoperative pain control, because noninvasive brain stimulation methods, such as rTMS and tDCS, may become attractive in the setting of multimodal analgesia.

Use of venovenous extracorporeal membrane oxygenation under regional anesthesia for a high-risk rigid bronchoscopy.

t b p p o w THERE ARE NUMEROUS indications for stent placement in the central respiratory tract.1 The mobilization or reoval of such stents using a rigid bronchoscope may expose atients to potentially severe respiratory complications. Reently, Chen2 reported the use of venoarterial extracorporeal membrane oxygenation (ECMO) during withdrawal of a stent covering the lower part of the trachea and the proximal part of the left mainstem bronchus. The first attempt resulted in almost complete obstruction of the trachea requiring resuscitation maneuvers. After conducting a thorough neurologic assessment of the patient, a 2nd attempt was performed on the following day. In order to ensure adequate oxygenation, the patient was put on venoarterial ECMO support under general anesthesia. The use of venovenous (VV) ECMO support set up under local anesthesia before the administration of general anesthesia in order to prevent oxygenation impairment because of the complexity of managing the airway or as a result of surgical intervention is reported.

Performance of acceleromyography with a short and light TOF-tube compared with mechanomyography: A clinical comparison

BACKGROUND Disturbances in the thumbs movement interfere with the functioning of acceleromyography in many clinical settings. The short and light (SL) train-of-four (TOF)-Tube is a new version of a rigid tubular device that was designed to protect the thumb from external disturbances during surgery, even when the hand is not accessible by the anaesthesiologist. OBJECTIVE To compare the precision and performance of acceleromyography performed with the aid of the SL TOF-Tube (AMGTT) with standard isometric mechanomyography (MMG). DESIGN Simultaneous arm-to-arm comparison of both methods in the same anaesthetised patient. SETTING A monocentric study, performed from September 2007 to June 2008. PATIENTS Nineteen ASA I to II patients scheduled to undergo lower limb orthopaedic surgery under general anaesthesia. INTERVENTION Neuromuscular transmission monitoring during baseline, onset and spontaneous recovery of rocuronium-induced neuromuscular block. MAIN OUTCOME MEASURES Initial baseline and repeatability coefficients were assessed during 10 consecutive measurements of the first twitch height (T1) and TOF T4/T1 ratio and compared using a z test. The spontaneous recoveries of defined blockade levels (onset, T1 25% of initial calibration and TOF ratio 0.9) were compared in terms of duration and intensity. Agreement between both techniques was assessed by the Bland–Altman method. RESULTS The mean ± SD control TOF ratios were 98 ± 1% (MMG) and 103 ± 2% (AMGTT). The repeatability coefficients were higher (P < 0.001) and the onset was longer (mean 0.44 min) (P < 0.001) when they were measured by AMGTT. The recoveries of T1 25% and TOF ratio 0.9 were not significantly different between the two methods, and the limits of agreement were in the usual range of contralateral comparisons (−19 and +24% for TOF ratio 0.9). CONCLUSION Compared with mechanomyography, acceleromyography performed with the aid of an SL TOF-Tube offered acceptable precision and equivalent performance during neuromuscular block recovery.

Fully Covered Metallic Stents for the Treatment of Benign Airway Stenosis.

Introduction. We herein report our experience with new fully covered self-expanding metallic stents in the setting of inoperable recurrent benign tracheobronchial stenosis. Methods. Between May 2010 and July 2014, 21 Micro-Tech® FC-SEMS (Nanjing Co., Republic of Korea) were placed in our hospital in 16 patients for inoperable, recurrent (after dilatation), and symptomatic benign airway stenosis. Their medical files were retrospectively reviewed in December 2014, with focus on stents tolerance and durability data. Results. Twenty-one stents were inserted: 13 for posttransplant left main bronchus anastomotic stricture, seven for postintubation tracheal stenosis, and one for postlobectomy anastomotic stricture. Positioning was easy for all of them. Stents were in place for a mean duration of 282 days. The most common complications were granulation tissue development (35%), migration (30%), and sputum retention (15%). Fifty-five % of the stents (11/20) had to be removed because of various complications, without difficulty for all of them. None of the patients had life-threatening complications. Conclusion. Micro-Tech FC-SEMS were easy to position and to remove. While the rate of complications requiring stent removal was significant, no life-threatening complication occurred. Further studies are needed to better define their efficacy and safety in the treatment of benign airway disease.