Life-Threatening Cardiac Arrhythmias during Anesthesia and Surgery

Life-threatening arrhythmias are frequently encountered during anesthesia for cardiac or non-cardiac surgery. They result in a significant cause of morbidity and mortality, particularly in elderly patients. Predisposing factors like electrolytes abnormalities, pre-existing cardiac disease, intubation procedure, anesthetic medications, and various surgical stimulation need to be determined. Early diagnosis and commencement of an appropriate treatment protocol may be lifesaving. Treatment usually involves correction of the underlying causes, cardiac electroversion, and the use of one or more antiarrhythmic agents. Although ventricular tachycardia, ventricular fibrillation, torsade de pointes, and pulseless electrical activity are considered malignant arrhythmias that can lead to cardiac arrest, other types of Brady and tachyarrhythmias are also included in this chapter to enable adopting a more objective approach in the management of arrhythmias intraoperatively, avoiding risks of inappropriate management strategies.

Surgical stimulation of uveoscleral outflow is an alternative to cyclodestructive procedures

Aim: to assess clinical efficacy and safety of surgical scleral rejection (SSR) vs. transscleral diode laser cyclophotocoagulation (TSCPC) in primary open-angle glaucoma (POAG) and secondary glaucoma (SG). Patients and Methods: study (prospective) group included 84 patients with POAG and SG after SSR. Control (retrospective) group included 80 patients after TSCPC. In addition, the patients were distributed by age and the stage and type of glaucoma, i.e., 128 patients were diagnosed with POAG and 36 patients were diagnosed with secondary thrombotic glaucoma. Follow-up was 24 to 36 months. IOP measurements, tonography (to assess the coefficient outflow facility / COF), ultrasound biomicroscopy of the anterior segment, visual acuity measurement, and visual field testing were performed. Results: no complications after SSR were reported in patients with POAG and SG. In contrast, postoperative complications (choroidal effusion, hyphema, and uveitis) were reported in 14% of patients after TSCPC. Long-term IOP-lowering efficacy of both procedures was similar (87% after SSR and 89% after TSCPC). In POAG, greater IOP reduction was seen after TSCPC (by 39.11%) compared to SSR (by 31.58%) (p<0.05). Meanwhile, in patients with SG, treatment outcomes were similar (IOP reduced by 36.78% after TSCPC and by 35.26% after SSR). In longterm follow-up, PVF reduced by 10.76% vs. baseline after TSCPC but increased by 11.19% vs. baseline after SSR (p≤0.05). Surgery resulted in the improvement or stabilization of visual functions. Ultrasonography has demonstrated that outflow pathways (intrascleral space and filtering bleb) remain functional after SSR in long-term follow-up. Conclusion: SSR is an alternative to cyclodestructive procedures in POAG and SG. Sclera being the final point of the uveoscleral outflow is a perspective entity to develop surgical approaches to glaucoma treatment. Keywords: surgical scleral resection, uveoscleral outflow, sclera, primary open-angle glaucoma, secondary glaucoma, glaucoma surgery, transscleral diode laser cyclophotocoagulation. For citation: Korchuganova E.A., Kazantzeva A.Yu. Surgical stimulation of uveoscleral outflow is an alternative to cyclodestructive procedures. Russian Journal of Clinical Ophthalmology. 2021;21(1):9–13. DOI: 10.32364/2311-7729-2021-21-1-9-13.

Stimulation of Liver Regeneration Using a Titanium Nickelide Implant (Experimental Study)

Currently, morbidity and mortality from chronic diffuse diseases of the liver and cirrhosis continue to increase worldwide. The difficulty of stabilizing the process with pharmacological agents, lots of restrictions for liver transplantation, the palliative character of the surgical correction of complications determine the urgency of finding various ways to stimulate liver regeneration, including surgical ones. Most of the known methods of surgical stimulation of regeneration are quite traumatic, and their stimulating effect is short-lived. The methods associated with cellular technologies are mostly expensive, ineffective, or poorly understood. In the experimental study, the effect on the parenchyma of a healthy and cirrhotic liver clips for clamping parenchymal organs exerting different unit pressure on the tissue was studied. The object of the study was laboratory rats with a healthy liver and animals with simulated cirrhosis. The animals were operated on with the imposition of titanium nickelide clips on the liver. Changes in the liver were studied 3, 7, 14, and 28 days after the surgery by histological examination of various parts of the liver. It was established that the clip with a lower specific pressure did not cause tissue necrosis, led to atrophy of the marginal part of the liver, also increased hepatocytes and binuclear hepatocytes were observed in the bulk of the liver. A decrease in the proportion of connective tissue was also observed in groups with liver cirrhosis. Thus, we consider it possible to use clips with a certain specific pressure on the tissue as a method of stimulating the reparative properties of the liver in chronic diffuse diseases and cirrhosis of the liver

Continuous Rate Infusion of Alfaxalone during Ketamine–Xylazine Anesthesia in Rats

Alfaxalone is an injectable anesthetic agent that is used in veterinary medicine for general anesthesia. We evaluated the safety and efficacy of alfaxalone delivered through continuous rate infusion by comparing ketamine–xylazine–alfaxalone (KXA) anesthesia with ketamine–xylazine (KX) anesthesia in Sprague–Dawley rats. Anesthesia was induced in male and female rats by using subcutaneous KX. After induction, rats in the KXA group received alfaxalone (10 mg/kg/h IV) for 35 min, whereas rats in the KX group did not receive alfaxalone. At the end of the trial, alfaxalone was discontinued, and xylazine was reversed in all rats by using atipamezole. Throughout anesthesia, we assessed forepaw withdrawal reflex (FPWR), hindpaw withdrawal reflex (HPWR), response to surgical stimulation, heart rate, respiratory rate, SpO2, body temperature, and time to standing. KXA produced a reliable surgical plane of anesthesia, as evidenced by the loss of both FPWR and HPWR and lack of response to surgical stimulation in all 16 rats, whereas only 6 of the 16 rats in the KX group lost HPWR. No rat in the KXA group regained a paw withdrawal reflex during alfaxalone administration, whereas 3 of the 12 rats (25%) in the KX group that reached a surgical plane of anesthesia exited that plane within the 35-min timeframe. Neither heart rate, respiratory rate, SpO2, body temperature, nor time to standing differed between KXA and KX groups; and there were no sex-associated differences in anesthesia response. These results indicate that alfaxalone (10 mg/kg/h IV) delivered through continuous rate infusion, in combination with ketamine and xylazine, provides a safe, prolonged, and reliable surgical plane of anesthesia in rats.

Practicalities of Total Intravenous Anesthesia and Target-controlled Infusion in Children

Propofol administered in conjunction with an opioid such as remifentanil is used to provide total intravenous anesthesia for children. Drugs can be given as infusion controlled manually by the physician or as automated target-controlled infusion that targets plasma or effect site. Smart pumps programmed with pharmacokinetic parameter estimates administer drugs to a preset plasma concentration. A linking rate constant parameter (keo) allows estimation of effect site concentration. There are two parameter sets, named after the first author describing them, that are commonly used in pediatric target-controlled infusion for propofol (Absalom and Kataria) and one for remifentanil (Minto). Propofol validation studies suggest that these parameter estimates are satisfactory for the majority of children. Recommended target concentrations for both propofol and remifentanil depend on the type of surgery, the degree of surgical stimulation, the use of local anesthetic blocks, and the ventilatory status of the patient. The use of processed electroencephalographic monitoring is helpful in pediatric total intravenous anesthesia and target-controlled infusion anesthesia, particularly in the presence of neuromuscular blockade.

Comparative efficacy of intravenous premedication of clonidine versus nalbuphine on intraoperative hemodynamic profile of patients during surgery under general anesthesia: a randomized study

Background: Airway manipulation and surgical stimulation lead to variable changes in hemodynamic profile due to increase in plasma catecholamine levels, but these changes can be attenuated by appropriate premedication. The present study was designed to compare the clinical efficacy of intravenous premedication of clonidine with nalbuphine on intraoperative hemodynamic profile of patients during surgery under general anaesthesia.Methods: Sixty adult consenting patients of ASA physical status I and II of either gender were randomized into two groups of 30 patients each, to receive either intravenous clonidine (2 μg/kg) or nalbuphine (0.2 mg/kg), 10 min before induction with propofol. Direct laryngoscopy and intubation were facilitated with vecuronium bromide. Changes in heart rate, blood pressure and electrocardiogram were recorded at specific time intervals and were noted as primary variable. Any adverse effects and complications were recorded as secondary outcomes.Results: After laryngoscopy and intubation, the increase in mean heart rate and mean blood pressure occurred immediately in patients of both groups, but persisted up to 6 to 10 min in patients of clonidine group, thereafter the changes returned back to baseline values, while in patients of nalbuphine group, this increase persisted up to 8 to 10 min. The differences in hemodynamic changes between the groups were statistically significant throughout the surgery and post extubation.Conclusions: Intravenous clonidine was more effective than nalbuphine to attenuate the hemodynamics changes during stressful period of laryngoscopy, intubation and surgery.

Effect of three opioid-based analgesic protocols on the perioperative autonomic-mediated cardiovascular response in sheep

Few reports evaluate the clinical effects of opioids in sheep during experimental surgical procedures. Catecholamine-mediated haemodynamic changes resulting from surgical noxious stimulation are blunted by opioids. The aim of this study was to evaluate the efficacy of three opioid-based analgesic protocols in avoiding a 20% increase in heart rate (HR) and/or mean arterial blood pressure (MAP) during experimental intervertebral disk nucleotomy in sheep. Eighteen female Brogna sheep were anaesthetized with propofol and maintained with a fixed end-tidal isoflurane concentration of 1.5 ± 0.1%. Sheep were assigned to one of three groups that intravenously received methadone 0.3 mg/kg (group M), fentanyl 2 µg/kg followed by 10 µg/kg/h (group F), or buprenorphine 10 µg/kg and 30 minutes later ketamine 1 mg/kg followed by 5 mg/kg/h (group BK). Intravenous fentanyl at 2 µg/kg would have been used for rescue analgesia in case HR and/or MAP had increased. During surgery, HR and MAP values did not increase over 20% in all groups. All animals maintained the percentage change between -4 and 7% for both variables; only one sheep in group BK had an increase in MAP superior to 20% after ketamine administration before surgical stimulation. In group M, HR decreased over time and in group BK, MAP tended to increase during surgery. All the opioid-based protocols tested were able to control the cardiovascular response to noxious stimulation in sheep undergoing spinal surgery, although ketamine may have represented a confounding factor.