A Prospective Study of Single Breath Vital Capacity Inhalation Induction with High Concentration of Sevoflurane (Sbvc-Hc) for LMA Insertion in Adults for Short Surgical Cases

Background: Sevoflurane is a new volatile anesthetic agent with rapid induction and recovery. A randomized study was carried to access conditions for LMA insertion using Sevoflurane in 25 ASA I & II patients undergoing short duration surgeries.Subjects and Methods:This prospective study was conducted at Department of Anesthesiology and Critical Care, SVS Medical College and Hospital, Mahabubnagar, Telangana, India. After obtaining the institutional ethics committee and written informed consent from the patients, 25 subjects of either sex were included in this study. Age of the subjects was 18 to 60 years. Patients received injection Fentanyl 1 – 2mcg/kg prior to induction. All patients were pre-oxygenated for 3 min with 100% oxygen using a fresh gas flow of 81/min. All patients received inhalational induction with 8% Sevoflurane and O2 flow at 8 L/min with single vital capacity breathe technique. Loss of verbal contact was considered as the desired endpoint for induction, which was assessed by the response to calling out the patient’s name. Then the time of loss of eyelash reflex and jaw relaxation was assessed by anesthesiologist. After adequate jaw relaxation, LMA insertion was attempted.Results:The mean loss of verbal contact was 65.40±9.67second, while the mean for time for loss of eyelash reflex and jaw relaxation were found to be 81.20±9.39 seconds and 103.20 ±12.07 seconds respectively. The mean time for LMA insertion was 122.00±15.61 and the mean attempts for successful LMA insertion was 1.12±0.33. LMA insertion was easy in 23 cases as against difficult in 2 cases. In 2 cases transient cough and biting were recorded. LMA insertion was excellent and satisfactory in 88.0 and 12 percent. However, the mean heart rate at 5 minute after induction showed a significant fall at 5 minutes after induction. The mean values of SBP, DBP and MAP did not differ significantly at pre and induction. However, a significant decrease in SBP was noticed at 1, 2 and at 5 minutes.Conclusion:Sevoflurane is an smooth inhalation anesthesia with rapid onset with adequate jaw relaxation for insertion of LMA in Adults for short duration surgeries. Sevoflurane has got good hemodynamic profile with lesser complications owing to choice of inhalation agent for insertion of LMA.

An Unusual Complication With the Administration of a Volatile Anesthetic Agent for Status Asthmaticus in the Pediatric Intensive Care Unit: Case Report and Review of the Literature

In severe cases of status asthmaticus, when conventional therapies fail, volatile anesthetic agents remain a therapeutic option. When delivered outside of the operating room setting, specialized delivery techniques are needed to ensure the safe and effective use of volatile anesthetic agents. We present a 16-year-old adolescent with status asthmaticus who required the therapeutic administration of the volatile anesthetic agent, sevoflurane, in the pediatric intensive care unit (PICU). Although initially effective in reducing bronchospasm, progressive hypercarbia developed due to defective functioning of the carbon dioxide absorber of the anesthesia machine. This failure occurred as the soda lime compartment filled with water accumulated from circuit humidification and continuous albuterol therapy. The role of volatile anesthetic agents in the treatment of status asthmaticus in the PICU is discussed, options for delivery outside of the operating room presented, and potential problems with delivery reviewed.

Dexmedetomidine as Part of Balanced Anesthesia Care in Children With Malignant Hyperthermia Risk and Egg Allergy

ABSTRACT Malignant hyperthermia is an acute hypermetabolic crisis triggered in susceptible patients by the administration of succinylcholine or a volatile anesthetic agent. When anesthesia care is provided to malignant hyperthermia-susceptible patients, a total intravenous anesthesia technique with propofol is frequently chosen. However, coexisting allergies to egg and soybeans may contraindicate the use of propofol. We present our experience with the use of dexmedetomidine as part of the anesthesia regimen in 3 patients with family histories of malignant hyperthermia and personal histories of egg or soybean allergies. In 2 patients, dexmedetomidine was used as part of a general anesthesia regimen and for sedation during spinal anesthesia in the third patient. Previous reports of the use of dexmedetomidine in patients susceptible to malignant hyperthermia are reviewed, and its benefits in such patients are discussed.

Nitrous Oxide Diffusion and the Second Gas Effect on Emergence from Anesthesia

Background Rapid elimination of nitrous oxide from the lungs at the end of inhalational anesthesia dilutes alveolar oxygen, producing "diffusion hypoxia." A similar dilutional effect on accompanying volatile anesthetic agent has not been evaluated and may impact the speed of emergence. Methods Twenty patients undergoing surgery were randomly assigned to receive an anesthetic maintenance gas mixture of sevoflurane adjusted to bispectral index, in air-oxygen (control group) versus a 2:1 mixture of nitrous oxide-oxygen (nitrous oxide group). After surgery, baseline arterial and tidal gas samples were taken. Patients were ventilated with oxygen, and arterial and tidal gas sampling was repeated at 2 and 5 min. Arterial sampling was repeated 30 min after surgery. Sevoflurane partial pressure was measured in blood by the double headspace equilibration technique and in tidal gas using a calibrated infrared gas analyzer. Time to eye opening and time extubation were recorded. The primary endpoint was the reduction in sevoflurane partial pressures in blood at 2 and 5 min. Results Relative to baseline, arterial sevoflurane partial pressure was 39% higher at 5 min in the control group (P < 0.04) versus the nitrous oxide group. At 30 min the difference was not statistically significant. Time to eye opening (8.7 vs. 10.1 min) and time to extubation (11.0 vs.13.2 min) were shorter in the nitrous oxide group versus the control group (P < 0.04). Conclusions Elimination of nitrous oxide at the end of anesthesia produces a clinically significant acceleration in the reduction of concentrations of the accompanying volatile agents, contributing to the speed of emergence observed after inhalational nitrous oxide anesthetic.

Mechanism of antiseizure effect of isoflurane in the immature rat hippocampus

The volatile anesthetic isoflurane is often used in children in the management of refractory status epilepticus. However the mechanism of anticonvulsant action of isoflurane during early brain development is not clear. In this study we explore the role of excitatory and inhibitory conductances in antiseizure effect of isoflurane using combination of whole-cell patch-clamp and extracellular field potential recording techniques on two models of epilepsy in a hippocampal slice preparation from immature rat. Our data demonstrated that decreasing of excitatory sy-naptic transmission does not account for antiseizure effect of this volatile anesthetic agent. Isoflurane decreases the synchro­nization of neuronal activity mainly through the enhancing of GABAergic inhibition by influencing both phasic and tonic chloride conductances.