Optimum End Tidal Sevoflurane Concentration Required for Intravenous Cannulation in Children

Background Inhalation mask induction is a cornerstone of pediatric anesthesia. Because of their natural aversion to needles, healthy children are usually anesthetized by mask prior to intravenous insertion. The early insertion of an intravenous access provides a means for administering fluids and drugs if an untoward event occurs during inhalational induction. Sevoflurane is the inhalation agent most commonly used for mask inductions in pediatric anesthesia, having largely replaced halothane for this purpose. Objectives The aim of the study was to evaluate the optimum end tidal concentration of Sevoflurane at which an intravenous cannulation can be successfully attempted without movement in pediatric patients. Patients and Methods In this clinical trial, pediatric subjects of either sex aged 2-5 years, weighing 10-20 kg were included. Results Showed that an end tidal sevoflurane of 1.46% has 50% probability for successful intravenous cannulation without movement in children. Conclusion We conclude that an end tidal sevoflurane of 1.46% has 50% probability for successful intravenous cannulation in un- premedicated children aged between 2 and 5 years.

Risk Factors for Postinduction Hypotension among Elderly Patients Undergoing Elective Non-Cardiac Surgery under General Anesthesia

Objective: We aimed to determine risk factors for hypotension occurring after induction among elderly patients (aged 65 years and older). We hypothesized that the dosage of intravenous anesthesia drugs as well as the type of inhalation agent have an effect on hypotension during post-induction periods. We aimed to test this hypothesis to determine risk factors for hypotension after induction among elderly patients who underwent non-cardiac surgery.Material and Methods: This retrospective cohort study analyzed data from 580 patients between December 2017 and July 2018 at a tertiary university hospital in the south of Thailand. Hypotension is defined as a more than 30.0% decrease in mean arterial pressure from baseline after induction and within 20 minutes of the use of a vasopressor agent to treat hypotension. The intraoperative parameters were blood pressure and heart rate immediately after arrival at the operating room, immediately after intubation, and 5, 10, 15, and 20 minutes after intubation.Results: The median age was 72.5 (68, 78) years. The association of post-induction hypotension was raised with a diuretic drug as preoperative medication (p-value=0.025), and the degree of hypertension immediately after arrival at the operating room (p-value<0.001). Increasing fentanyl dosage during induction was associated with hypotension (p-value<0.010). There was no statistically significant difference in the increase of the propofol dosage.Conclusion: The degree of hypertension immediately after arrival at the operating room coupled with higher fentanyl dosage were significant risk factors for postinduction hypotension in elderly patients.

SEVOFLURANE REQUIREMENT TO ATTENUATE STRESS RESPONSE TO PNEUMOPERITONEUM AND POST-OPERATIVE ANALGESIA DURING LAPAROSCOPIC CHOLECYSTECTOMY: INTRATHECAL DEXMEDETOMIDINE VS. FENTANYL. A PROSPECTIVE RANDOMISED STUDY

Background and aims: Laparoscopic cholecystectomy is considered as the gold standard for cholelithiasis with better preservation of surgical anatomy, early recovery and post-operative analgesia but haemodynamic instability due to pneumo-peritoneum is a concern. This study was contemplated to assess the effect of intrathecal dexmedetomidine or fentanyl on end-tidal inhalation agent concentration requirement as an indirect measure of haemodynamic stress response during the creation of pneumo-peritoneum and on post-operative analgesia. Methods: This prospective, randomized, comparative study was conducted in 75 ASA I and II patients with three groups of 25 each. The patients in group-1 received 10µg of intrathecal dexmedetomidine, group-2 50µg fentanyl and group-3 equal volume of normal saline before administration of general anesthesia. We assessed the vital parameters and end-tidal concentration of sevourane requirement before and 10minutes after creation and immediately after deation of pneumo-peritoneum. Post-operative pain scores were measured using Visual analogue scale(VAS) for 24hrs and rescue analgesia was 0.5µg/kg fentanyl in the immediate post-operative period and paracetamol 15mg/kg if the score was ≥4 in the post-operative period. Results: Demographic data were comparable in all the groups. Systolic blood pressure before onset of pneumo-peritoneum(P=0.03),endtidal inhalation agent concentration to maintain stable haemodynamics post-pneumoperitoneum were signicantly low(P=0.036) in group-1 as compared to group-3. Immediate bolus dose requirement of fentanyl after extubationwas signicantly low, and the duration of post-operative analgesia was prolonged(P=0.009) in group-1.Conclusion: Intrathecal dexmedetomidine may be a safe and effective method in alleviating haemodynamic stress response during pneumo-peritoneum and provides adequate post-operative analgesia in laparoscopic cholecystectomy.

Effects of Dexmedetomidine Infusions on Hemodynamic Stability in Patients undergoing Laparoscopic Cholecystectomy

Objectives: In laparoscopic cholecystectomy, there has been emphasis on maintaining hemodynamic stability by avoiding hypertension, hypotension, or tachycardia. The hemodynamic instability is persistent during the duration of pneumoperitoneum (PNP), namely, CO2 insufflations. This study helps us to find out the efficacy of dexmedetomidine on cardiovascular system stability in patients undergoing laparoscopic cholecystectomy. Materials and methods: Thirty patients were randomized into two groups of 15 members each: group P (placebo group) and group D (dexmedetomidine group). In the former, patients received 0.9% 20 mL normal saline, while in the latter, patients received 0.4 μg/kg/hr of injection dexmedetomidine in 0.9% normal saline. In all patients, age, weight, height, systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were recorded. Results: Dexmedetomidine being a highly selective and potent and specific alpha 2 agonist attenuates the hemodynamic response to tracheal intubation, decreases plasma catecholamine concentration during anesthesia, and decreases perioperative requirements of inhaled anesthetics. We found that dexmedetomidine helped in blunting the pressor response during the intubation, kept the HR and mean arterial pressure stable intraoperatively, and there was faster recovery as the requirement of inhalation agent was decreased intraoperatively. Conclusion: The drug dexmedetomidine maintained cardiovascular stability during laparoscopic cholecystectomy. The inhalational agent (isoflurane) requirement was found to be considerably lower. Also, the mean recovery time as indicated by the ability to vocalize following extubation was found to be significantly less. Hence, it can be recommended in laparoscopic cholecystectomy for maintaining cardiovascular system stability.

High risk of intraoperative awareness during cardiopulmonary bypass with isoflurane administration via diffusion membrane oxygenators

In cardiac surgery with the aid of extracorporeal circulation (ECC), inhalation anaesthetics can be administered via the oxygenator. Until the recent advent of a new type of diffusion membrane oxygenator, we routinely added the inhalation agent, isoflurane, to the gas flow of a micro-porous capillary membrane-type oxygenator. Applying this procedure to the diffusion-type oxygenators, the depth of anaesthesia appeared to be affected, which manifested itself through unusually high intraoperative perfusion pressures. This observation led to a prospective randomized study comprising 60 patients and two models of a microporous capillary membrane oxygenator, as well as two models of a diffusion membrane oxygenator. Simultaneous isoflurane concentration measurements at both the gas inlet and outlet ports of the oxygenators showed that, whereas in the microporous capillary-type oxygenators the isoflurane administered was reduced by about 50% during the passage of gas through the device, there was only a minimal transfer of isoflurane in the diffusion-type membrane oxygenators.