Flow Anesthesia Research Articles

The Effect of Low- Flow Anesthesia on Hemodynamic Parameters and Gas Consumption in Single Lung Ventilation

The Effect of Low- Flow Anesthesia on Hemodynamic Parameters and Gas Consumption in Single Lung Ventilation

A randomised prospective comparison of equilibration point and changing gas composition during low-flow anaesthesia with sevoflurane vs desflurane.

Background and Aims:Safety and economy are the main concerns while using low- flow anaesthesia with newer inhalational agents. The main objective of this study was to use and compare 'equilibration time' of sevoflurane and desflurane after change-over from high-to-low flow anaesthesia.Methods:This prospective study included consenting adult patients between 18–70 years undergoing elective surgery under general anaesthesia. Patients were randomised initially to receive high-flow anaesthesia with 1.3 MAC of either desflurane or sevoflurane with nitrous oxide. After equilibration point, low-flow anaesthesia was initiated. Heart rate, non-invasive blood pressure, pulse oximeter, 5 electrode ECG and gas monitoring was done. Statistical analysis was done with the help of Med CalC version 12.5.0.0 (student version) and IBM SPSS Version 20.0.Results:Mean equilibration time in sevoflurane group was higher (4.59 ± 0.77 minutes) than desflurane group (3.78 ± 0.56 minutes, P < 0.001). Inspired concentrations of both inhalational agents varied from their vaporiser settings over 2 hours, more so with sevoflurane than desflurane. Inspired oxygen concentration (FiO2) remained above 30% during anaesthesia in both groups with stable haemodynamics.Conclusion:Change-over from high-to-low flow anaesthesia is faster in desflurane. With fresh gas flow (FGF) of 1 L with 50% oxygen and dial concentration of 1–1.5% of sevoflurane and 3.8–4.4% of desflurane, the risk of hypoxia is minimal. The disparity between the set and delivered concentrations is more (20%) in sevoflurane than desflurane (12%).

Precautionary practices for administering anesthetic gases: A survey of physician anesthesiologists, nurse anesthetists and anesthesiologist assistants

ABSTRACTScavenging systems and administrative and work practice controls for minimizing occupational exposure to waste anesthetic gases have been recommended for many years. Anesthetic gases and vapors that are released or leak out during medical procedures are considered waste anesthetic gases. To better understand the extent recommended practices are used, the NIOSH Health and Safety Practices Survey of Healthcare Workers was conducted in 2011 among members of professional practice organizations representing anesthesia care providers including physician anesthesiologists, nurse anesthetists, and anesthesiologist assistants. This national survey is the first to examine self-reported use of controls to minimize exposure to waste anesthetic gases among anesthesia care providers. The survey was completed by 1,783 nurse anesthetists, 1,104 physician anesthesiologists, and 100 anesthesiologist assistants who administered inhaled anesthetics in the seven days prior to the survey. Working in hospitals and outpatient surgical centers, respondents most often administered sevoflurane and, to a lesser extent desflurane and isoflurane, in combination with nitrous oxide. Use of scavenging systems was nearly universal, reported by 97% of respondents. However, adherence to other recommended practices was lacking to varying degrees and differed among those administering anesthetics to pediatric (P) or adult (A) patients. Examples of practices which increase exposure risk, expressed as percent of respondents, included: using high (fresh gas) flow anesthesia only (17% P, 6% A), starting anesthetic gas flow before delivery mask or airway mask was applied to patient (35% P; 14% A); not routinely checking anesthesia equipment for leaks (4% P, 5% A), and using a funnel-fill system to fill vaporizers (16%). Respondents also reported that facilities lacked safe handling procedures (19%) and hazard awareness training (18%). Adherence to precautionary work practices was generally highest among nurse anesthetists compared to the other anesthesia care providers. Successful management of waste anesthetic gases should include scavenging systems, hazard awareness training, availability of standard procedures to minimize exposure, regular inspection of anesthesia delivery equipment for leaks, prompt attention to spills and leaks, and medical surveillance.

Mass-spectrometric investigation of degradation of the inhalation anesthetic sevoflurane in flow anesthesia

The highest concentration of the Sevoflurane degradation product in the gas mixture was 65 ppm. Biochemical analysis did not reveal any nephro- and hepatotoxic effect.

Amsorb: A New Carbon Dioxide Absorbent for Use in Anesthetic Breathing Systems

We have developed a new carbon dioxide absorbent for use during low flow or circle system anesthesia. The material does not contain the strong base sodium and/or potassium hydroxide. This paper discusses the efficiency and chemical inertness of the new material.

Effect of palatal injections on pulpal blood flow in premolars

The effect of palatal infiltration injections using 2% lignocaine hydrochloride with 1:80,000 adrenaline was evaluated for sound maxillary first premolar teeth. The influence of the injections on pulpal blood flow and local anaesthesia was investigated. Ten human volunteers were given the following injections on different days: 1 ml palatal infiltration; 1 ml buccal infiltration; 1 ml palatal and 1 ml buccal infiltration; and 2 ml buccal infiltration. The blood flow was observed with a laser Doppler flowmeter with the probes held against the buccal surfaces of the teeth by a splint. Blood flow was recorded digitally on a computer in machine units. Pulpal anaesthesia was assessed using a monopolar electric pulp tester. All injections significantly reduced blood flow from baseline levels (p<0.05). The 1-ml palatal injection produced a significantly longer period of reduced blood flow (mean 40 min) compared with the other injections (p<0.05). The duration of blood flow reduction was shorter than the duration of pulpal anaesthesia for every injection. Only seven out of 10 palatal injections achieved pulpal anaesthesia. The 2-ml buccal injection and the combined buccal and palatal injections produced significantly longer anaesthesia than the 1-ml buccal injection (p<0.05).

Cerebral Circulation and Metabolism

This volume contains the papers presented at the 6th International Symposium on Cerebral Blood Flow and Metabolism held in Philadelphia, June 1973. The papers themselves are succinctly presented and well edited. Each session is followed by a chairman's summary, which crystalizes the information presented under the general headings of Autoregulation, Chemical Control, Focal Lesions, Methodology, Ischemia, Clinical Stroke, Intracranial Pressure and Cerebral Blood Flow Monitoring, Pharmacology and Anesthesia, and Neurogenic Control and Metabolism. It is particularly interesting to consider this authoritative compendium by looking back on the 25-year span of interest in the subject, which was initiated at the University of Pennsylvania in 1945 when Drs Seymour Kety and Carl F. Schmidt perfected their method for the measurement of total cerebral blood flow. Their innovation spawned enormous activity in the field of cerebral flow and metabolism, beginning with physiology and pharmacology of the human cerebral circulation and expanding to clinical

Altered perfusion, ventilation, anesthesia and lung-surface forces in dogs.

The combination of hyperventilation, lowered pulmonary blood flow and pentobarbital-O2 anesthesia led to a progressive increase in retractive forces of the lung accompanied by a gradual reduction in inflatable volume in dogs studied for eight hours. After four hours of ventilation, significant changes began to appear at the higher transpulmonary pressures. Results after four hours of ventilation were similar in other dogs treated identically except for the addition of 1.2 per cent halothane to the inspired gas. Hyperventilation and the absence of pulmonary arterial blood flow led to significant (P