D. Vasilakos

Ropivacaine myotoxicity after single intramuscular injection in rats

Background and objective: We conducted this study in order to evaluate the potential myotoxic effects of ropivacaine after single injection in rats and the time‐course of the possible damage. Methods: One hundred and twenty‐eight male Wistar rats were allocated to four different groups. The first three groups received intramuscular injections with ropivacaine 0.75%, ropivacaine 0.5% and normal saline, respectively, into the right tibialis anterior muscle. The fourth group received needle puncture without injection. Eight rats from each group were sacrificed 2, 4, 7 and 30 days after injection. Samples were blindly examined under light microscope for evidence of myotoxicity, scored as 0 = no damage to 3 = myonecrosis and statistically analysed. Samples obtained 7 days after injection were also examined under transmission electron microscope. Results: Ropivacaine 0.75% and ropivacaine 0.5% caused extensive destruction to muscles fibres, compared to saline or needle on days 2, 4 and 7. Statistically significant differences were found in muscle damage by drug injections among all groups except for saline vs. needle groups. Thirty days after injections all sample appearances had returned to normal. Conclusions: Ropivacaine after single intramuscular injection caused reversible muscle damage in a dose‐dependent manner.

Effect of perioperative electroacupuncture as an adjunctive therapy on postoperative analgesia with tramadol and ketamine in prostatectomy: a randomised sham-controlled single-blind trial.

Objectives To study the analgesic effect of electroacupuncture (EA) as perioperative adjunctive therapy added to a systemic analgesic strategy (including tramadol and ketamine) for postoperative pain, opioid-related side effects and patient satisfaction. Methods In a sham-controlled participant- and observer-blinded trial, 75 patients undergoing radical prostatectomy were randomly assigned to two groups: (1) EA (n=37; tramadol+ketamine+EA) and (2) control (n=38; tramadol+ketamine). EA (100 Hz frequency) was applied at LI4 bilaterally during the closure of the abdominal walls and EA (4 Hz) was applied at ST36 and LI4 bilaterally immediately after extubation. The control group had sham acupuncture without penetration or stimulation. The following outcomes were evaluated: postoperative pain using the Numerical Rating Scale (NRS) and McGill Scale (SF_MPQ), mechanical pain thresholds using algometer application close to the wound, cortisol measurements, rescue analgesia, Spielberger State Trait Anxiety Inventory (STAI Y-6 item), patient satisfaction and opioid side effects. Results Pain scores on the NRS and SF_MPQ were significantly lower and electronic pressure algometer measurements were significantly higher in the EA group than in the control group (p<0.001) at all assessments. In the EA group a significant decrease in rescue analgesia was observed at 45 min (p<0.001) and a significant decrease in cortisol levels was also observed (p<0.05). Patients expressed satisfaction with the analgesia, especially in the EA group (p<0.01). Significant delays in the start of bowel movements were observed in the control group at 45 min (p<0.001) and 2 h (p<0.05). Conclusions Adding EA perioperatively should be considered an option as part of a multimodal analgesic strategy.

Correlation of central venous-arterial and mixed venous- arterial carbon dioxide tension gradient with cardiac output during neurosurgical procedures in the sitting position

Background and objective The study was conducted to evaluate the correlation of central venous–arterial and mixed venous–arterial pCO2 gradient with cardiac output in patients being operated in the sitting position. Methods Fifty-one patients, aged 41–69 years, classified as American Society of Anesthesiologists physical status II and III, scheduled to undergo elective neurosurgical procedures in the sitting position, were enrolled in this prospective cohort study. Simultaneous blood gas samples from arterial, central venous and pulmonary artery catheters were collected at four different time points during supine and sitting position. Cardiac index (CI) determination was accomplished simultaneously, with continuous cardiac output technique. The mixed venous–arterial pCO2 and central venous–arterial pCO2 gradients were calculated and related to CI at the specific time points, thus a total of 204 points of comparison were obtained. Results Changing from the supine to the sitting position induced a significant deterioration of CI, right atrial pressure, mean pulmonary arterial pressure and pulmonary wedge pressure. The mean delta pCO2 difference (bias) in the four time points ranged between −0.07 and −0.27. The upper (1.59–1.71 mmHg) and lower limits of agreement (−2.16 to −1.82 mmHg) were quite narrow, suggesting an acceptable overall agreement between the mixed and central venous pCO2 differences. The coefficient of determination (R2) between the venous–arterial pCO2 and CI for mixed and central venous circulations was 0.830 and 0.760 (P < 0.001 for both), respectively. In contrast, R2 values between mixed and central venous oxygen saturation values and CI were 0.324 and 0.286, respectively (P < 0.001 for both), illustrating a rather weak relationship. Conclusion It seems that venous–arterial pCO2 values obtained from mixed and central venous circulations can be reliably interchanged in estimating CI in patients undergoing neurosurgical procedures in the sitting position. Thus, central venous–arterial pCO2 gradient could serve as a useful and simple method for estimating cardiac performance, in which further invasive monitoring is not strongly indicated.

Postoperative analgesia after low-frequency electroacupuncture as adjunctive treatment in inguinal hernia surgery with abdominal wall mesh reconstruction

Objective To determine whether an electroacupuncture (EA) technique that was developed for a surgical population under general anaesthesia reduces pain after mesh inguinal hernia open repair. Methods A total of 54 patients with right or left inguinal hernia were randomised to group I (preoperative, intraoperative, postoperative EA), group II (preoperative, postoperative EA), or a sham control group (group III; preoperative and postoperative placement of needles, but without skin penetration). The Visual Analogue Scale (VAS) (primary outcome) and the State-Trait Anxiety Spielberger Inventory were evaluated preoperatively and at 30 min, 90 min, 10 h and 24 h after surgery. Pain threshold and tolerance were evaluated using an algometer at these same time points and preoperatively before and after EA. Levels of the stress hormones cortisol, corticotrophin and prolactin were determined at 30 min, 90 min and 10 h after surgery and preoperatively before and after EA. Results The results showed significant differences between the true EA and control groups. The true EA groups (I and II) showed statistically significantly greater improvements in the primary (VAS pain, p<0.05) and secondary outcome measures (Anxiety scale; algometer measurements, p<0.05 and stress hormones, p<0.01) compared to the control group. There were no statistically significant differences between groups I and II. Conclusions Electroacupuncture reduces postoperative pain after mesh inguinal hernia repair and decreases stress hormone levels and anxiety during the postoperative period. Trial Registration Number ClinicalTrials.gov identifier NCT01722253.

Comparison between intubation through ILMA and Airtraq, in different non-conventional patient positions: a manikin study.

Background Tracheal intubation is often difficult in the prehospital setting, especially in trapped casualties, when long extrication time is anticipated and conventional laryngoscopy cannot be achieved. The aim of the present study was the comparison of applicability and efficacy of two alternative techniques: intubation using a laryngeal mask airway (ILMA) or an Airtraq laryngoscope in different patient positions, using an airway management manikin. Methods 20 anaesthetists attempted manikin intubations standing behind the manikin (Sup), standing in front and facing the manikins head (Fac), facing the manikin in the sitting position (Sit) and facing the manikin lying in the lateral decubitus position (Lat), using either Airtraq or ILMA techniques. The intubations were evaluated regarding the success rate, number of attempts and time needed for successful intubation, teeth damage and overall difficulty. Results All intubation attempts were successful for both techniques. Intubations through ILMA were completed with a significantly greater number of attempts and longer time in the Lat position, compared to Fac, Sit and Sup (p<0.05), whereas intubations using Airtraq in the Sup and Fac positions were completed with a significantly greater number of attempts and longer time, compared to Sit and Lat positions (p<0.05). Both ILMA and Airtraq can be used for securing the airway when direct laryngoscopy is impossible due to patient position. ILMA seems to cause greater difficulty in the Lat position, whereas Airtraq intubation is more easily performed in the Sit and Lat positions. Conclusions These preliminary data in manikins could indicate the applicability of the methods to the prehospital setting.

Reversal of neuromuscular blockade with sugammadex in an obese myasthenic patient undergoing thymectomy

To the Editor: Myasthenia gravis (MG) is an autoimmune disease often characterized by circulating antibodies that block acetylcholine receptors at the postsynaptic neuromuscular junction. The resulting modified neuromuscular transmission leads to an unpredictable response in the administration of neuromuscular blocking agents in case of surgery. We challenged the use of sugammadex, a modified c-cyclodextrin, to reverse a deep rocuronium-induced blockade in a 31-year-old obese [95 kg; 1.60 m; body mass index (BMI) 37 kg/m] female myasthenic patient. The patient was literally disabled, mainly from severe weakness affecting limb muscles, resulting in repetitive falls [Myasthenia Gravis Foundation of America (MGFA) class IVa]. She was referred for transsternal thymectomy due to a grossly hyperplastic thymus gland. Her daily dose of pyridostigmine was 240 (60 9 4) mg. Preoperative blood gases in room air were satisfactory: partial pressure of arterial oxygen (PaO2) 93 mmHg and carbon dioxide (PaCO2) 36 mmHg, pH 7.43, saturation of peripheral oxygen (SpO2) 96%. Sugammadex encapsulates the steroidal neuromuscular-blocking agents (NMBAs) rocuronium and vecuronium, resulting in prompt reduction of free NMBA plasma concentration and rapid restoration of muscular activity. It lacks endogenous targets and is unlikely to cause any major adverse effects [1]. The patient was not premedicated; she received her usual dose of pyridostigmine. After induction (140 mg propofol, 0.25 mg fentanyl intravenously), neuromuscular monitoring was applied [baseline train-of-four (TOF) ratio T4/T1 0.92–1.02). NMBAs have variable sensitivity in MG. Thus, dosage has to be carefully titrated and neuromuscular function continuously monitored [2, 3]. For this reason, repetitive TOF stimulation (TOF-Watch SX) was applied intraoperatively. Anesthesia was initially maintained with propofol 5 mg/kg per hour and then titrated according to bispectral index (BIS) values (target 40–50). A single bolus of rocuronium 0.5 mg/kg was administered to facilitate tracheal intubation. No maintenance doses of rocuronium were given. The neuromuscular blockade was considered adequate throughout surgery. At the end of the 70-min surgical procedure (extended thymectomy), the TOF ratio was 0.3. The neuromuscular blockade was considered as deep compared with preoperative values, and a dose of 2 mg/kg sugammadex was administered intravenously. Within 3 min, the TOF ratio was 0.92; 7 min later, it was 1.02. The patient returned to spontaneous breathing (pressure support 15 cm/H2O, tidal volume 700 ml, respiratory rate 14 breaths/min) with satisfactory blood gases (PaO2 297 mmHg, PaCO2 41 mmHg, pH 7.42, SpO2 98%). Clinically, the patient was able to lift her head, open her eyes, and protrude her tongue. She was extubated in the operating room 10 min after the end of surgery. The patient had a 24 h-stay in the intensive care unit and had an uneventful recovery. She left the hospital in a good condition on the seventh postoperative day. This case demonstrates that sugammadex effectively and safely reversed a deep rocuronium-induced neuromuscular blockade in an obese MG patient and allowed prompt weaning from mechanical ventilation postoperatively. Moreover, the surgical procedure (transsternal approach) has H. Argiriadou (&) E. Thomaidou D. Vasilakos Department of Anesthesia and Intensive Care Medicine, Aristotle University of Thessaloniki, AHEPA University Hospital, Thessaloniki, Greece e-mail: argiriadouhelena@hotmail.gr

Baroreceptors discharge due to bilateral aortic denervation evokes acute neuronal damage in rat brain

Deep hypothermic circulatory arrest in cardiothoracic surgery evokes severe brain damages. On the other hand, blood pressure stimuli discontinuation to the brain has been found to induce alterations in neurotransmitter release, including glutamate, in numerous brain regions. Furthermore, it is well established that excessive glutamate release can induce neuronal injury, a process called excitotoxicity. Aim of the present study was the evaluation of possible acute neuronal damage after bilateral aortic denervation (bAD), imitating the baroreceptors discharge during circulatory arrest. Male, Wistar rats underwent either bAD or Sham operation under continuous hemodynamic monitoring. Two hours after completion of the procedure, rats were sacrificed and the brains were dissected and cut in specific levels corresponding to selective brain regions, based on either their participation in neuronal circuits, regulating blood pressure, or their vulnerability, after deep hypothermic circulatory arrest. Slices were stained and examined under light microscope using morphometric techniques. Increased number of necrotic neurons were found among bAD rats in amygdaloid complex (p=0.005), motor cortex (p=0.001), CA1 and CA3 (p=0.02 and 0.015) but not in posterior hypothalamic nucleus and Purkinje cell. Higher ratios of necrotic neurons were found in amygdaloid complex (p=0.002), motor layer (p=0.003 and p=0.000) and the hippocampal CA1 region (p=0.027) of bAD rats. The present study shows that baroreceptors discharge due to bAD may induce acute neuronal loss in brain regions involved in blood pressure regulation. Neuronal loss might be attributed to excitotoxic phenomena and it is following the same topographic distribution seen in deep hypothermic circulatory arrest, revealing a concurrent to hypoxia/ischemia mechanism of brain damage.

A Multidisciplinary Approach to Unplanned Conversion from Off-Pump to On-Pump Beating Heart Coronary Artery Revascularization in Patients with Compromised Left Ventricular Function

Aim. To comparably assess the perioperative risk factors that differentiate off-pump coronary artery bypass (OPCAB) grafting cases from those sustaining unplanned conversion to on-pump beating heart (ONCAB/BH) approach, in patients with left ventricular ejection fraction (LVEF) < 40%. Methods. Perioperative variables were retrospectively assessed in 216 patients with LVEF < 40%, who underwent myocardial revascularization with OPCAB (n = 171) or ONCAB/BH (n = 45) approach. The study endpoints were operative mortality (30-day) and morbidity assessed by length of intensive care unit stay (LOS-ICU), using 2 days as cut-off point. Results. Poor LVEF, increased EuroSCORE II, acute presentation, congestive heart failure, cerebrovascular disease, perioperative renal impairment, clinical status deterioration upon admission and during ICU stay, acute myocardial infarction, and low cardiac output syndrome supported by inotropes and/or balloon-pump counterpulsation were significantly related to ONCAB/BH group (P < 0.05). EuroSCORE II (P = 0.01) and LVEF (P = 0.03) were the most powerful discriminative predictors of intraoperative conversion to ONCAB/BH. Operative mortality was 2.9% in OPCAB and 6.6% in ONCAB/BH group (P = 0.224), while 23.4% participants in OPCAB and 42.2% in ONCAB/BH approach had a LOS-ICU > 2 days (P = 0.007). Conclusions. Patients with LVEF < 40% undergoing ONCAB/BH are subjected to more preoperative comorbidities and implicated ICU stay than their OPCAB counterparts, which influences adversely short-term morbidity, while operative mortality remains unaffected.

Electroacupuncture on a patient with pacemaker: a case report

Electroacupuncture (EA) is commonly used for pain relief, with good results even in persistent chronic pain. However, published reports suggest that EA should not be used in patients who have pacemaker, since there is a theoretical risk of malfunction of the pacemaker. The case is described of a 50-year-old female patient, who has had severe low back pain resistant both to conventional and unconventional treatment methods. The only treatment that seemed to have some positive effect, but of extremely short duration, was acupuncture. Her condition deteriorated considerably, and after due consideration she was treated with EA. Even after the first EA treatment, the patients condition improved. Since then, she has received many EA courses during the past 2 years without any complications or side effects. The results of this case study suggest that EA might be a safe alternative for patients with a pacemaker, confirming the current recommendations on use. Every patient should be considered with care, individually.

The Effect of Four Anaesthetic Protocols for Maintenance of Anaesthesia on Trans-Diaphragmatic Pressure in Dogs

The diaphragm is the main inspiratory muscle and the main indicator of diaphragmatic contractility is the trans-diaphragmatic pressure (Pdi). The aim of this clinical study was to determine the effect of four different anaesthetic protocols on Pdi in anaesthetized healthy dogs. Eighty client-owned dogs were recruited in this clinical study. All the animals received dexmedetomidine and morphine as premedication and propofol for induction. Anaesthesia was maintained with one of four protocols: isoflurane (I), isoflurane with CRI of propofol (IP), isoflurane with CRI of fentanyl (IF), and isoflurane with CRI of ketamine (IK). When the surgical plane of anaesthesia was achieved, two balloon catheters were inserted, one into the stomach and one into the mid-third of the oesophagus for Pdi measurement. Pdi value was the highest in groups I (14.9±4.7 mmHg) and IK (15.2±3.5 mmHg) and the lowest in groups IP (12.2±3.2 mmHg) and IF (12.0±5.9 mmHg). There was a statistically significant difference (p = 0.029) between groups IK and IF. PE’CO2 was statistically significantly higher (p<0.0005) in group IF (7.7±0.8 kPa) than in group IK (6.5±0.7 kPa). Isoflurane alone or isoflurane with ketamine for the maintenance of anaesthesia seem to better preserve the respiratory function and the diaphragmatic contractility than isoflurane with either propofol or fentanyl in dogs. Therefore, the use of isoflurane or isoflurane with ketamine may be of benefit when animals with respiratory problems have to be anaesthetized.