M. Mercieri

Microvascular dysfunction and skeletal muscle oxygenation assessed by phase-modulation near-infrared spectroscopy in patients with septic shock

ObjectiveSepsis is now considered a disease of the microcirculation. Little is known about the various sepsis-induced changes responsible for microvascular dysfunction. We investigated human microvascular function, regulation, oxygenation, and cellular metabolism during subacute septic shock.Design and settingProspective case-control study in a nine-bed polyvalent surgical ICU of a university hospital.Patients and participantsA prospectively enrolled group of 26 patients (13 with septic shock, 13 nonseptic postsurgical patients) and 15 healthy volunteer controls.Measurements and resultsThe absolute tissue hemoglobin concentrations (oxygenated hemoglobin and deoxyhemoglobin) were measured noninvasively in arterioles, capillaries, and venules by phase-modulation near-infrared spectroscopy in the human brachioradial muscle during a series of venous occlusions and an arterial occlusion (ischemia) induced by applying a pneumatic cuff. These measurements were used to calculate tissue blood volume, postischemic hemoglobin resaturation time, microvascular compliance, and O2 consumption. Patients with sepsis had significantly higher tissue blood volume values and lower compliance than healthy controls. They also had longer postischemic hemoglobin resaturation times than the other two groups and blunted resaturation curves. O2 consumption was lower in patients with sepsis than in healthy controls. In patients with septic shock cuff-induced ischemia left O2 consumption unchanged, whereas in healthy volunteers it reduced O2 consumption to values almost matching those of patients with septic shock.ConclusionsThese findings show that septic shock alters microvascular muscle function and regulation. Diminished local VO2 presumably reflects maldistribution and faulty autoregulation of local blood flow.

Combined intrathecal and epidural magnesium sulfate supplementation of spinal anesthesia to reduce post-operative analgesic requirements : a prospective, randomized, double-blind, controlled trial in patients undergoing major orthopedic surgery

Background:  New ways of decreasing post‐operative analgesic drug requirements are of special interest after major surgery. Magnesium sulfate (MgSO4) alters pain processing and reduces the induction and maintenance of central sensitization by blocking the N‐methyl‐d‐aspartate (NMDA) receptor in the spinal cord. We investigated whether supplementation of spinal anesthesia with combined intrathecally and epidurally infused MgSO4 reduced patients’ post‐operative analgesia requirements.

Emerging treatment for chronic migraine and refractory chronic migraine

Introduction: Chronic migraine (CM), the suffering of 15 or more headache days with at least 8 of these migraine days, afflicts 1.3% - 5.1% of the global population. CM is the most common disorder faced by experts in tertiary headache centers. When resistant to conventional medical treatment and prophylactic medication this condition is known as refractory chronic migraine (RCM). RCM is one of the greatest challenges in headache medicine. Areas covered: State-of-the-art and future medical treatments of chronic migraine include: OnabotulinumtoxinA, antiepileptic drugs (Levetiracetam, Magnesium valproate hydrate, Lacosamide, BGG-492), 5-HT agonists (Lasmiditan, NXN-188, novel delivery systems of Sumatriptan, a well-established drug treatment for acute migraine), CGRP receptor antagonists (BMS-927711), ML-1 agonists (Ramelteon), orexin receptor antagonist (MK-6096), plant-derived compound (LLL-2011) and other multitarget drugs such as Tezampanel, Tonabersat, intranasal carbon dioxide and BOL-148. The role for neuromodulation, the application of targeted electrical stimulation, will be examined. Expert opinion: Medication overuse headache (MOH) is now recognized to be a major factor in many cases of both chronic and refractory chronic migraine. MOH must be addressed prior to evaluating the effectiveness of new preventative and prophylactic treatment approaches. Innovative new drugs and electrical neuromodulation are promising CM treatments. Future studies must carefully screen patients and acquire data that can lead to personalized, tailored treatment strategies.

Lateral popliteal sciatic nerve block: a single injection targeting the tibial branch of the sciatic nerve is as effective as a double-injection technique

Background:  Evidence indicating that single‐ and double‐injection techniques for inducing a sciatic nerve block via a posterior subgluteal approach yield a similar success rate prompted us to investigate whether the two anesthetic techniques yield a similar success rate via a lateral approach. We also hypothesized that, owing to the peculiar anatomic features of the sciatic nerve at the popliteal level, a single injection via the lateral approach might induce effective anesthesia by targeting the tibial nerve only.

Cervical 10 kHz spinal cord stimulation in the management of chronic, medically refractory migraine: A prospective, open-label, exploratory study

A significant minority of chronic migraine (CM) subjects fail conventional medical treatment (rCM), becoming highly disabled. Implantation of an occipital nerve stimulator is a therapeutic option for these subjects. Paresthesia‐free cervical 10 kHz spinal cord stimulation (HF10 SCS) may provide an alternative. We report the results of a prospective, open‐label, exploratory study assessing the long‐term safety, tolerability and efficacy of cervical HF10 SCS in cohort of rCM subjects.

Effects of sternotomy on heart-lung interaction in patients undergoing cardiac surgery receiving pressure-controlled mechanical ventilation

Background:  The key concept underlying the dynamic indexes of preload dependence is the physiological heart–lung interaction. During sternotomy this interaction undergoes various changes, some of which remain unclear. Our primary aim was to investigate how the interaction changes during sternotomy by evaluating pulse pressure variations (PPV) with the chest closed and after sternotomy in patients ventilated using the pressure‐controlled mode.

Tetraplegia following parathyroidectomy in two long-term haemodialysis patients

We report two cases of postoperative iatrogenic tetraparesis, which occurred in different hospitals after surgery for parathyroidectomy. Both patients were on long‐term haemodialysis. The prolonged neck extension usually required by this procedure was probably the main factor involved in the genesis of the spinal cord injury. Spinal abnormalities associated with chronic renal failure may have made these patients more vulnerable. In our opinion, it is advisable to investigate thoroughly any sign of spinal stenosis in patients who undergo any procedure requiring significant neck extension, particularly if on long‐term haemodialysis.

Critical pneumonia complicating early-stage pregnancy

We present a case of community-acquired methicillin-resistant Staphylococcus aureus necrotizing pneumonia, Panton-Valentine leukocidin positive, in a woman at 14 weeks of pregnancy. To our knowledge, this is the first case reporting this critical lung infection occurring during an early phase of pregnancy. This case study alerts physicians to the increasing worldwide spread of these uncommon yet virulent and potentially lethal infections. In our patient, antibiotic therapy with linezolid plus rifampin started at 14 weeks of pregnancy had a successful outcome without inducing toxicity or teratogenesis in the fetus.

Optical Guidance Systems for Epidural Space Identification

Epidurals are the most diffused loco-regional techniques for the relief of operative, postoperative, and chronic pain and are used for about 50% of deliveries. Currently, doctors still identify epidural space relying on subjective perception, by using “blind” manual techniques to which are associated failure rate up to 7%. In the last years, many systems aimed at assisting and guiding the placement of epidural needle have been proposed. In particular, optical systems basically rely on the integration inside the epidural needle lumen of optical fiber probes providing real-time discrimination of differing tissue types during needle penetration. In this study, aside of providing an exhaustive overview on the systems proposed so far, we also report on a novel sensorized medical needle, based on the judicious integration of a fiber Bragg grating sensor inside the epidural needle lumen. Our device, by providing continuous and real-time measurements of the pressure experienced by the needle tip during its advancement, is able to effectively detect the needle passage from one tissue to the other. A pilot study carried out on an epidural training phantom demonstrates the validity of our approach for making the needle placement into the epidural space easier and safer.

Changes in cerebrospinal fluid magnesium levels in patients undergoing spinal anaesthesia for hip arthroplasty: does intravenous infusion of magnesium sulphate make any difference? A prospective, randomized, controlled study

BACKGROUND Most investigators have attributed the reduced postoperative pain or anaesthetic drug requirements in patients receiving i.v. magnesium sulphate (MgSO(4)) infusion during spinal or general anaesthesia to central N-methyl-d-aspartate (NMDA) receptor magnesium (Mg) activity. In this study, we investigated how cerebrospinal fluid (CSF) Mg concentrations change after spinal anaesthesia, and whether peripherally infusing MgSO(4) influences central Mg levels. METHODS Forty-five patients undergoing continuous spinal anaesthesia for hip arthroplasty were randomly assigned to receive either i.v. MgSO(4) at a dose of 50 mg kg(-1) diluted in 100 ml 0.9% saline solution followed by 15 mg kg(-1) h(-1) for 6 h or saline at the same volume [mean (sd) 64 (10) ml]. The changes in CSF and serum total and ionized Mg concentrations were assessed at six time points before and after spinal anaesthesia. Secondary outcome variables included serum and CSF electrolytes and proteins. RESULTS Thirty-five patients completed the study. We found that spinal anaesthesia reduced total and ionized Mg concentrations in CSF by about 10%. Increasing serum Mg concentration over 80% of the baseline value left CSF Mg levels unchanged. CONCLUSIONS Spinal anaesthesia unexpectedly reduced CSF total and ionized Mg concentrations in patients undergoing hip arthroplasty, although the mechanism is unclear. The dose used for peripheral MgSO(4) infusion in this study had no influence on central Mg concentrations in neurologically healthy patients undergoing spinal anaesthesia. If CSF Mg concentration is a reliable marker of Mg brain bioavailability, peripherally infused MgSO(4) during spinal anaesthesia is unlikely to influence central NMDA receptor activity.