One-minute heart rate variability - an adjunct for airway obstruction identification.

Heart rate variability (HRV) reflects cardiac and autonomic nervous system activity. It is usually measured over a relatively prolonged period and presented using multiple parameters. Here, we studied rapid HRV changes during airway obstruction using a short (1 min) sampling window. Forty healthy volunteers underwent a trial of obstructed breathing. Heart rate was recorded during three consecutive sets comprised of 1-min control followed by 1 min of obstructed breathing, with 1 min of rest between sets. Time and frequency domain analysis were used to compare HRV during control versus obstructed breathing. Compared with control, HRV intensely increased during obstructed breathing: R-R intervals (time between consecutive R waves) standard deviation increased from 65 to 108 msec (P < 0.0001), root mean square of successive R-R interval from 61 to 82 msec (P = 0.001), number of pairs of successive R-R intervals that differ by more than 50 msec (NN50) from 16.5 to 25.3 events (P < 0.0001), and proportion of NN50 divided by total number of R-R intervals from 26.6 to 35.1% (P = 0.001). Low frequency power increased by more than fourfold (P < 0.0001), allowing 90% sensitivity and 75% specificity for identifying airway obstruction (ROC area 0.88, P < 0.0001). We observed a rapid intense increase in HRV during obstructed breathing, significant enough to detect during a short 1-min sampling window. These findings suggest that HRV may be useful for rapid detection of airway obstruction, especially in situations where end-tidal CO2 monitoring is not optimal, such as during partial airway obstruction.

The Role of the Anesthesiologist during Magnetic Resonance-Guided Focused Ultrasound Thalamotomy for Tremor: A Single-Center Experience.

Ablative incisionless neurosurgery has become possible through advances in focused ultrasound and magnetic resonance imaging (MRI). The great advantage of MRI-guided focused ultrasound (MRgFUS) is that the ablation is performed through an intact skull without surgery. Here, we review the new modality of MRgFUS for treating tremor and enlighten the role of the anesthesiologist in the unique procedural setting of the MRI suite. During the MRgFUS process, the patients should be awake and are required to cooperate with the medical staff to allow assessment of tremor reduction and potential occurrence of adverse effects. In addition, the patient's head is immobilized inside the MRI tunnel for hours. This combination presents major challenges for the attending anesthesiologist, who is required to try to prevent pain and nausea and when present, to treat these symptoms. Anxiety, vertigo, and vomiting may occur during treatment and require urgent treatment. Here, we review the literature available on anesthetic management during the procedure and our own experience and provide recommendations based on our collected knowledge.

Comparison of the performance of battery-operated fluid warmers.

OBJECTIVES: Warming intravenous fluids is essential to prevent hypothermia in patients with trauma, especially when large volumes are administered. Prehospital and transport settings require fluid warmers to be small, energy efficient and independent of external power supply. We compared the warming properties and resistance to flow of currently available battery-operated fluid warmers. METHODS: Fluid warming was evaluated at 50, 100 and 200 mL/min at a constant input temperature of 20°C and 10°C using a cardiopulmonary bypass roller pump and cooler. Output temperature was continuously recorded. RESULTS: Performance of fluid warmers varied with flows and input temperatures. At an input temperature of 20°C and flow of 50 mL/min, the Buddy Lite, enFlow, Thermal Angel and Warrior warmed 3.4, 2.4, 1 and 3.6 L to over 35°C, respectively. However, at an input temperature of 10°C and flow of 200 mL/min, the Buddy Lite failed to warm, the enFlow warmed 3.3 L to 25.7°C, the Thermal Angel warmed 1.5 L to 20.9°C and the Warrior warmed 3.4 L to 34.4°C (p<0.0001). CONCLUSION: We found significant differences between the fluid warmers: the use of the Buddy Lite should be limited to moderate input temperature and low flow rates. The use of the Thermal Angel is limited to low volumes due to battery capacity and low output temperature at extreme conditions. The Warrior provides the best warming performance at high infusion rates, as well as low input temperatures, and was able to warm the largest volumes in these conditions.

Investigating the cardiac pathology of SCO2-mediated hypertrophic cardiomyopathy using patients induced pluripotent stem cell-derived cardiomyocytes.

Mutations in SCO2 are among the most common causes of COX deficiency, resulting in reduced mitochondrial oxidative ATP production capacity, often leading to hypertrophic cardiomyopathy (HCM). To date, none of the recent pertaining reports provide deep understanding of the SCO2 disease pathophysiology. To investigate the cardiac pathology of the disease, we were the first to generate induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs) from SCO2-mutated patients. For iPSC generation, we reprogrammed skin fibroblasts from two SCO2 patients and healthy controls. The first patient was a compound heterozygote to the common E140K mutation, and the second was homozygote for the less common G193S mutation. iPSC were differentiated into cardiomyocytes through embryoid body (EB) formation. To test the hypothesis that the SCO2 mutation is associated with mitochondrial abnormalities, and intracellular Ca2+ -overload resulting in functional derangements and arrhythmias, we investigated in SCO2-mutated iPSC-CMs (compared to control cardiomyocytes): (i) the ultrastructural changes; (ii) the inotropic responsiveness to ß-adrenergic stimulation, increased [Ca2+ ]o and angiotensin-II (AT-II); and (iii) the Beat Rate Variability (BRV) characteristics. In support of the hypothesis, we found in the mutated iPSC-CMs major ultrastructural abnormalities and markedly attenuated response to the inotropic interventions and caffeine, as well as delayed afterdepolarizations (DADs) and increased BRV, suggesting impaired SR Ca2+ handling due to attenuated SERCA activity caused by ATP shortage. Our novel results show that iPSC-CMs are useful for investigating the pathophysiological mechanisms underlying the SCO2 mutation syndrome.

Comparison of Rhabdomyolysis Markers in Patients Undergoing Bariatric Surgery with Propofol and Inhalation-based Anesthesia.

BACKGROUND: Rhabdomyolysis is a relatively uncommon, severe complication of anesthesia and surgery in the morbidly obese. As the use of propofol-based anesthesia has been associated with an increased risk of rhabdomyolysis and metabolic acidosis, this pilot study was designed to assess the effect of propofol anesthesia on the incidence of rhabdomyolysis in morbidly obese patients undergoing bariatric surgery. METHODS: Thirty, morbidly obese patients (body mass index 43 ± 3 kg/m(2)) scheduled for bariatric laparoscopic sleeve gastrectomy were randomized to receive either propofol (P) or inhalational anesthetic (I)-based balanced general anesthesia. A sample of venous blood gas analysis including pH, bicarbonate concentrations, and calculated base excess was taken at the end of the operation. Creatine phosphokinase (CPK), troponin I, blood urea nitrogen, and creatinine plasma concentrations were measured at the end of the surgery and again 24 h later. RESULTS: All patients enrolled to the study completed it without significant complications. CPK, troponin I, blood urea nitrogen, and creatinine plasma concentrations at the end of the operation and at 24 h, as well as the bicarbonate concentration and the base excess at the end of the operation were not significantly different between the two study groups. A statistically significant mild respiratory acidosis was noted in the inhalational anesthetic group (pH 7.30 ± 0.04 vs. 7.36 ± 0.02 in the propofol group) CONCLUSIONS: This small-size pilot study may suggest that propofol-based anesthesia is not related to increased incidence of rhabdomyolysis in morbidly obese patients undergoing short, uncomplicated bariatric surgery.

Verification of intravenous catheter placement by auscultation--a simple, noninvasive technique.

BACKGROUND: Verification of proper placement of an intravenous catheter may not always be simple. We evaluated the auscultation technique for this purpose. METHODS: Twenty healthy volunteers were randomized for 18G catheter inserted intravenously either in the right (12) or left arm (8), and subcutaneously in the opposite arm. A standard stethoscope was placed over an area approximately 3 cm proximal to the tip of the catheter in the presumed direction of the vein to grade on a 0-6 scale the murmur heard by rapidly injecting 2 mL of NaCl 0.9% solution. The auscultation was evaluated by a blinded staff anesthesiologist. RESULTS: All 20 intravenous injection were evaluated as flow murmurs, and were graded an average 5.65 (±0.98), whereas all 20 subcutaneous injections were evaluated as either crackles or no sound, and were graded an average 2.00 (±1.38), without negative results. Sensitivity was calculated as 95%. Specificity and Kappa could not be calculated due to an empty false-positive group. CONCLUSIONS: Being simple, handy and noninvasive, we recommend to use the auscultation technique for verification of the proper placement of an intravenous catheter when uncertain of its position. Data obtained in our limited sample of healthy subjects need to be confirmed in the clinical setting.

A Call of Alert for the Ambu AuraStraight Disposable Laryngeal Mask.

One day after removal of an AuraStraight disposable laryngeal mask, a plastic laryngeal mask airway cuff shield was retrieved from the oropharynx of a 5-year-old child refusing to eat, drooling, and pointing to her throat. We discuss the reasons why this occurred and suggest how it can be prevented in the future.

Monitoring the nociception level: a multi-parameter approach.

The aim of the present study was to develop and validate an objective index for nociception level (NoL) of patients under general anesthesia, based on a combination of multiple physiological parameters. Twenty-five patients scheduled for elective surgery were enrolled. For clinical reference of NoL, the combined index of stimulus and analgesia was defined as a composite of the surgical stimulus level and a scaled effect-site concentration of opioid. The physiological parameters heart rate, heart rate variability (0.15-0.4 Hz band power), plethysmograph wave amplitude, skin conductance level, number of skin conductance fluctuations, and their time derivatives, were extracted. Two techniques to incorporate these parameters into a single index representing the NoL have been proposed: NoLlinear, based on an ordinary linear regression, and NoLnon-linear, based on a non-linear Random Forest regression. NoLlinear and NoLnon-linear significantly increased after moderate to severe noxious stimuli (Wilcoxon rank test, p < 0.01), while the individual parameters only partially responded. Receiver operating curve analysis showed that NoL index based on both techniques better discriminated noxious and non-noxious surgical events [area under curve (AUC) = 0.97] compared with individual parameters (AUC = 0.56-0.74). NoLnon-linear better ranked the level of nociception compared with NoLlinear (R = 0.88 vs. 0.77, p < 0.01). These results demonstrate the superiority of multi-parametric approach over any individual parameter in the evaluation of nociceptive response. In addition, advanced non-linear technique may have an advantage over ordinary linear regression for computing NoL index. Further research will define the usability of the NoL index as a clinical tool to assess the level of nociception during general anesthesia.

Skin electrical resistance does not change following infraclavicular block.

Peripheral nerve blocks are common and effective means for anesthesia for limb surgery. The evaluation of the success of a peripheral blockade is based on the loss of sensation, with no objective means of detecting a successful block. The autonomic innervation to the upper extremity, which controls both the vascular tone and the activity of sweat glands, is supplied by nerve fibers accompanying the somatic nerve fibers. Previous studies have shown changes in both skin temperature and electrical resistance of the skin following brachial plexus block. We studied 20 patients undergoing hand surgery under infraclavicular brachial plexus block. The electrical resistance of the skin on the palmar aspect of the forearm was continuously recorded on the block arm and on the contralateral arm using a commercial skin resistance monitor. No statistically significant change in the electrical resistance of the skin was observed during 20 minutes after placement of the block. These results strongly suggest that the electrical resistance of the skin cannot be used to predict a successful infraclavicular block.

Prolonged nerve blockade in a patient treated with lithium.

We report a case of a patient, chronically treated with oral lithium, who presented with an extremely prolonged (42-hour) duration of sensory and motor paralysis following an uneventful infraclavicular block for hand surgery that was performed under ultrasound guidance using bupivacaine and lidocaine. Due to its direct effect on nerve conduction of action potential, we propose that lithium may have had a role in the unusually prolonged duration of a peripheral nerve block.

[Perioperative anti-platelet therapy management--protocol suggestion].

BACKGROUND: Currently, dual antiplatelet treatment is conducted with aspirin and clopidogrel. Preterm termination of combined treatment may cause morbidity and mortality. In patients about to undergo surgery, antiplatelet treatment is withheld before the operation to avoid perioperative excessive bleeding. As a consequence, these patients are at high perioperative thromboembolic risk. AIM: A perioperative antiplatelet management protocol developed by a dedicated committee will be presented. This protocol guides the physician while preparing the patient for surgery through three steps: (a) What is the indication for dual antiplatelet treatment and what are the patient's thrombotic risk factors? (b) How severe is the expected operative bleeding? (c) The combination of steps (a) and (b) leads to a recommendation on whether to stop antiplatelet treatment, when and for how long, or to continue antiplatelet treatment throughout the operation. In extreme cases, the indication for antiplateLet treatment may be absolute (for example: 2 months after a drug eluting stent coronary implantation), but the expected operative bleeding is very high and the operation cannot be deferred (e.g., neurosurgery for growth removal). Such cases are referred to an expert consulting committee. EXPECTED RESULTS: Many articles have pointed out the problems of current perioperative antiplatelet management and call for change. A precise assessment of the patient's indications, risk factors and perioperative bleeding, as guided by the suggested protocol, will result in better antiplatelet perioperative treatment, and will avoid both thromboembolic and bleeding risks.

Warmflo warming system overheats fluids in simulated clinical conditions.

STUDY OBJECTIVE: To evaluate the Warmflo fluid warming system at various flow rates of crystalloid solution simulated to clinical conditions. DESIGN: Prospective analysis and laboratory investigation. SETTING: Operating room and technical laboratory of a university-affiliated hospital. MEASUREMENTS: The Warmflo WF-100 fluid warming (heat exchanger) cassette of the Warmflo FW-538 fluid warming system was primed with lactated Ringer's solution. The fluid warming system was adjusted to temperature set points of 38 degrees C or 42 degrees C. The temperature of the solution flowing through the warming system was measured inside the infusion line downstream from the heat exchanger cassette at the proximal and distal sites, with flow rates of two, 10, and 100 mL/min and simultaneously inside the warming housing between the heater plates. MAIN RESULTS: Average temperature of the solution measured inside the infusion line at the proximal site ranged between 33.4 (+/-1.35) degrees C and 34.0 (+/-2.23) degrees C at a flow rate of two mL/min when the temperature set point was 38 degrees C. At all other flow rates at either set point, the solution temperature was above 37.5 degrees C inside the infusion line, reaching up to 43.9 degrees C at a flow rate of 100 mL/min and a set point of 42 degrees C. Temperatures inside the warming housing ranged from 40.6 (+/-0.26) degrees C to a maximum of 48.0 (+/-0.85) degrees C at a set point of 42 degrees C after the flow stopped. CONCLUSIONS: The Warmflo fluid warming system can overheat fluids at temperatures considerably above normal body temperatures.

The 18-kDa translocator protein, formerly known as the peripheral-type benzodiazepine receptor, confers proapoptotic and antineoplastic effects in a human colorectal cancer cell line.

OBJECTIVE: The involvement of the 18-kDa translocator protein (TSPO), formerly known as the peripheral-type benzodiazepine receptor, in apoptosis regulation of HT29 colorectal cancer cells was studied in-vitro. In-vivo TSPO involvement in tumor growth of HT29 cells xenografted into SCID mice was studied. METHODS: Knockdown of TSPO expression in the human HT29 cell line was established by stable transfection with vectors containing the TSPO gene in the antisense direction. Successful TSPO knockdown was characterized by reduction of 20% in TSPO RNA levels, 50% in protein expression of the TSPO, and 50% in binding with the TSPO ligand, [3H]PK 11195. Subsequently, in-vitro cell viability and proliferation assays were applied. In addition, transient transfecton with short interfering RNA (siRNA) directed against human TSPO was studied in this way. Furthermore, we also grafted HT29 cells subcutaneously into the right thighs of SCID mice to examine the effects of the putative TSPO agonist, FGIN-1-27, on tumor growth in-vivo. RESULTS: In-vitro TSPO knockdown established by stable transfection of TSPO antisense gene resulted in HT29 clones displaying significantly lower levels of cell death as determined with trypan blue (50% less), lower apoptotic rates (28% less), and higher proliferation rates (48% more one week after seeding and 27% more two weeks after seeding). Transient transfection with anti-human TSPO siRNA resulted in similar viability and antiapoptotic effects. In-vivo, the proapoptotic TSPO ligand, FGIN-1-27 significantly reduced the growth rate of grafted tumors (40% less), in comparison with vehicle-treated mice. CONCLUSION: TSPO knockdown by genetic manipulation transforms the human HT29 cancer line to a more malignant type in-vitro. In-vivo pharmacological treatment with the putative TSPO agonist FGIN-1-27 reduces tumor growth of the HT29 cell line. These data suggest that TSPO involvement in apoptosis provides a target for anticancer treatment.

Pathophysiology and clinical implications of microbubbles during hemodialysis.

Microbubbles have been detected in the human circulation of end-stage renal disease patients who are treated by hemodialysis throughout the past decade as a result of advanced ultrasound and Doppler technology. These detection tools uncovered signals of microbubbles, which originate in extracorporeal lines and tubing of hemodialysis machine, circulate in the blood stream until lodging in the capillary bed of various organs, mainly the lungs. During its course within the capillary, a bubble abrades the glycocalyx layer lining the surface of the vessels and thereafter obstructs blood flow through the capillary. This causes tissue ischemia, inflammatory response, and complement activation. Aggregation of platelets and clot formation occurs as well, leading to further obstruction of the microcirculation and subsequent tissue damage. In this review, we describe the biological and clinical effects of microbubbles during hemodialysis and discuss management with regard to prevention and treatment.

[Retrograde tracheal intubation--an alternative in difficult airway management].

Secured airway is a must in spontaneous or assisted ventilation. A variety of methods are in clinical use for establishing an airway, of which endotracheal intubation is the most common. Difficulties in establishing a secured airway may deteriorate to a serious, and even a life-threatening situation. The management of difficult airways indicates the use of advanced, urgent means, and may lead to surgical intervention. This article describes an alternative technique for tracheal intubation, useful in such cases. Retrograde tracheal intubation is carried out by percutaneous insertion of a needle into the trachea in the subglotic region, passing a guidewire through the needle cephaled until it exits the mouth or nose and threading an endotracheal tube over the guidewire into the trachea. This technique is relatively easy and safe, and should be considered in difficult airway management.

Perioperative morbidity and mortality in 80 years and older undergoing elective urology surgery - a prospective study.

BACKGROUND AND PURPOSE: The number of octogenarians requiring surgery increases constantly. Data regarding perioperative morbidity and mortality in octogenarians is limited. Our aim was to assess surgery-related complications in octogenarians, undergoing urological surgery. PATIENTS AND METHODS: We prospectively collected data from octogenarians and a control group of younger patients undergoing an elective urological surgery in our institution. Recorded data included: age, gender, American Society of Anesthesiologists (ASA) score, co-morbidities, number of medications, operation extent, anaesthesia type, surgery duration and perioperative morbidity and mortality. RESULTS: Forty-seven octogenarians and 80 patients with a median age of 59 years (range 19-75) enrolled prospectively. Gender ratio, surgeries extent and median operative time were similar among groups. General anaesthesia was more prevalent in the control group. ASA classification and duration of hospitalization were significantly higher in octogenarians. The rate of intra-operative complications was significantly higher in the octogenarians group 6.38% versus 3.75% (p = 0.007), there was no significant difference in immediate post-operative and post-discharge complications among groups. One octogenarian patient died 2 days post-surgery, no death occurred in the control group. CONCLUSIONS: Octogenarians have higher rate of intra-operative morbidity, leading to longer hospital stay. More experienced surgeons and anaesthetists should be involved in the operation; and careful surgical technique, tapered anaesthesia and higher level of post-operative monitoring should be applied for patients in this age.

Low-volume interscalene brachial plexus block for post-thoracotomy shoulder pain.

OBJECTIVES: This study was designed to evaluate the effectiveness of low-volume interscalene brachial plexus block for post-thoracotomy ipsilateral shoulder pain and to compare it with nonsteroidal anti-inflammatory drug treatment. DESIGN: Prospective nonblinded study. SETTING: University hospital. PARTICIPANTS: Sixty adult patients. INTERVENTION: Patients who underwent elective thoracic surgery under combined epidural and general anesthesia, and after surgery were free of incisional pain but complaining of shoulder pain, were included in the study. They were selected in a sequential manner and placed into 2 groups of 30 patients each. Group 1 had a low-volume interscalene brachial plexus block, using 10 mL of bupivacaine 0.5%. Group 2 had an intramuscular injection of diclofenac sodium, 75 mg. MEASUREMENTS AND MAIN RESULTS: Pain was measured during their stay in the postanesthesia care unit (PACU) by using a visual analog score (VAS). Opioids were administered when pain relief was incomplete. Pain intensity was re-estimated the next morning and patient satisfaction was scored. VAS was found to be significantly lower in the low-volume interscalene block group than in the diclofenac group at 30 minutes after treatment and when leaving PACU (p < 0.001 for both). Patients in the interscalene block group stayed longer in the PACU (p = 0.019), and significantly fewer required rescue opioids (p = 0.03). There was no significant difference between the groups in patient satisfaction with the pain treatment. CONCLUSIONS: The authors concluded that low-volume interscalene brachial plexus block is a superior treatment for post-thoracotomy shoulder pain compared with diclofenac injection, although it requires a slightly longer stay in the PACU.