Articles Comments

Anesthesia General » General Anesthesia

Anesthesia for Carotid Endarterectomy

Anesthesia for Carotid Endarterectomy is of proven benefit to reduce the risk of stroke in patients with high-grade stenosis of the internal carotid artery. Since the disease is atherosclerotic in origin, these patients often are prone to a variety of cerebrovascular and myocardial complications during the perioperative phase. Anesthesia for Carotid Endarterectomy demands excellent haemodynamic stability due to the risk of perioperative myocardial damage. A deep or superficial cervical plexus block is often used to provide regional Anesthesia for Carotid Endarterectomy . Simple local infiltration (field block) has also been widely used as an effective technique. General anaesthetic techniques that have been used include inhalational agent based, narcotic-based or hypnotic-based. Neurologic assessment of the awake patient is the gold standard for neurologic monitoring during Anesthesia for Carotid Endarterectomy . Regional anaesthesia allows a … Read entire article »

Filed under: General Anesthesia

Excess Oxygen

Excess Oxygen can cause pulmonary oxygen toxicity which results in a lot of damage to the body tissues. To summarize briefly, the excess oxygen can cause, pulmonary toxicity, Acute respiratory distress syndrome, rertolental fibroplasia, convulsions and Paul burt effect. Here we will be dicussing the mechanisms of these tissue injuries that occur with use of excess oxygen. The following the changes at the tissue level that can happen with excess oxygen usage: • Mitochondrial damage due to enzyme malfunction. This is the main reason for the different problems occuring with excess oxygen. • Surfactant production is impaired, and the lung tends to collapse. • Histological changes such as atelectasis, pulmonary capillary congestion, interstitial and alveolar oedema, capillary degeneration and haemorrhage, etc. • There is fall in heart rate and cardiac output, causing mild to severe haemodynamic derangements. • Generalized increase in the peripheral vascular resistance and systemic pressure … Read entire article »

Filed under: General Anesthesia

Low alveolar ventilation

A lot of anesthetic gases can be dangerous when used in a low alveolar ventilation anesthesia. This is because the anesthetic gases can combine with soda lime or other components of the boyles machine and produce poisonous gases. This is constant in a non-rebreathing system. In low alveolar ventilation you might see that there can be anesthetic loss to plastic and soda lime. This is high with Methoxyflurane <Halothane and Sevoflurane; none with desflurane and N20. Drysoda lime degrades halothane and sevoflurane to some extent. Dehydration of baralyme increases compound A production from sevoflurane. Re breathing lowers the inspired concentration of anaesthetic agent. In the circle system also there is some amount of rebreathing, so a low alveolar ventilation concentration of the agent occurs. The low-flow delivery systems provide a constancy of anaesthetic levels. An advantage of low alveolar ventilation is that it avoids wastage of … Read entire article »

Filed under: General Anesthesia

Wong baker pain assessment tool

Wong baker pain assessment tool is used in the patients who do not have appropriate cognitive level to use a number scale, like lay persons or children. The patient then points out to face best represents how he/she is feeling at that point of time. The patient must be explained correlation between each face and its correlation with pain. The Wong baker pain assessment tool depicts 6 faces from happy face to a crying grimace face. The method was devised for the first time by a pediatric nurse consultant, Donna Wong, and a child life specialist, Connie Morain Baker. Initially, the numbers 0-5 were used to quantify the pain, but using the numbers 0-2-4-6-8-10 is easier as it is more consistent with the numeric scale of 0-10. The Wong baker pain assessment tool has indeed made the detection and grading … Read entire article »

Filed under: General Anesthesia

Ethyl Chloride Anesthesia

  Ethyl Chloride Anesthesia is a potent anaesthetic. If it has a bp of 12.5°C and hence is a gas at room temperature, so it is liquefied and stored under pressure in a bottle with a cap and seal. It is used as a spray. It is cardiotoxic, explosive, reacts with soda lime, and is flammable. It is used as a spray to hypothermise areas and render numb for incision of small abscesses. Ethyl Chloride Anesthesia is pleasant, VP 988, flammable, affected by soda lime. 3- 5 mL is sufficient to induce anaesthesia in 1-2 minutes. Ethyl Chloride Anesthesia was the last to be introduced in the 19th century, and like ether, it was flammable. It was a unique agent that was first used as a spray to induce local anesthesia, but if … Read entire article »

Filed under: General Anesthesia

Trilene anesthesia

  Trilene anesthesia is a non-flammable, good analgesic-and cheap agent. Physical properties of trilene anesthesia : It has bp 80°C, VP 60 mm Hg, oil/gas coefficient 600 and blood/gas 12, metabolism 40%, unstable, preservative 1:10,000 thymol as stabilizer and coloured with waxoline blue 1 in 200,000, MAC 0.17%. Trilene anesthesia reacts with sodalime to produce phosgene which is neurotoxic. In light planes it is a good analgesic and was used in inhalational labour analgesia. Deep anaesthesia may resuit in tachypnoea due to accentuation of Herring-Breuer reflex and is arrhythmogenic. It is metabolized to chloral hydrate and in presence of soda lime to phosgene and carbon monoxide. In a difficult situation trilene anesthesia can be used in a draw-over vapourizer. It can be used in semiclosed circuit on the Boyle’s machine bottle or Tritec … Read entire article »

Filed under: General Anesthesia

Methoxyflurane Anesthesia

  Methoxyflurane Anesthesia is a halogenated hydrocarbon now obsolete. Physical properties: Colourless, fruity liquid, non-flammable, bp104°C, blood/gas coefficient 13, oil /gas 825, VP 25 mm Hg, MAC 0.2%, metabolism 50-75%. Methoxyflurane Anesthesia is metabolized to dichloroacetic acid and methoxydifluoro acetic acid and fluoride in high amount which proved nephrotoxic; due to this it has been abandoned. We can read the following about methoxyflurane anesthesia in Miller’s Anesthesia 7th edition - No discussion of immune-mediated hepatotoxicity after inhaled halogenated anesthetics is complete without a brief discussion of methoxyflurane. From a historical perspective, methoxyflurane anesthesia was introduced into clinical practice in the United States in 1960. There have been a number of reports of hepatic dysfunction and death from hepatic coma after exposure to methoxyflurane. A review of 24 cases of methoxyflurane anesthesia associated hepatitis revealed that a syndrome similar … Read entire article »

Filed under: General Anesthesia

Enflurane metabolism

  Enflurane metabolism is briefly discussed. About 80-90% of enflurane is eliminated in expired air, up to 5% is metabolized by hepatic cytochrome P450 (2E1) to difluoromethoxy difluoroacetic acid and free fluoride. Carbon monoxide may be produced in the presence of dry soda lime or baralyme, at higher temperatures and higher anaesthetic concentrations. Also while studying enflurane metabolism the Induction with enflurane is prompt and smooth. Similarly emergence is usually prompt, muscle relaxation allows easy intubation. Shivering may occur as seen with other agents. Miller’s Anesthesia says the following about enflurane metabolism - Enflurane (CHF2-O-CF2-CHClF) is essentially no longer used in the United States, but examination of its metabolism serves to illustrate how relatively minor changes in chemical structure can dramatically affect the extent of metabolism. Approximately 2.5% of the enflurane absorbed is metabolized . Initial … Read entire article »

Filed under: General Anesthesia

Enflurane side effects

Some of the Enflurane side effects are studied below. There is a narrow margin of safety between adequate anaesthesia, unacceptable hypotension and myocardial depression. One of the enflurane side effects includes the seizure activity is rare and without sequelae. Hepatic dysfunction is rare but cross sensitization with other volatile inhalation agents possible. With prolonged anaesthesia and at higher concentration, plasma fluoride may exceed 50 micro mol with possible nephrotoxicity. The myocardial effects, seizure activity and possible nephrotoxicity and other enflurane side effects has discouraged its clinical use. After initial clinical trails in India, it was not commercially introduced in India. Miller’s anesthesia says the following about enflurane side effects - In contrast with their direct vasodilatory actions, halothane, isoflurane, enflurane, and desflurane attenuate KATP channel– and endothelin-mediated pulmonary vasodilation in chronically instrumented dogs. Inhibition of pulmonary … Read entire article »

Filed under: General Anesthesia

Sevoflurane respiratory effects

Some of the Sevoflurane respiratory effects include that there is no irritation to the airway, least among inhalation agents, this makes it suitable for inhalational induction, the low blood/gas solubility aids faster induction. Sevoflurane respiratory effects include  respiratory depression, reduces minute ventilation, tidal volume and ventilatory response to CO2. Sevoflurane abolishes hypoxic pulmonary vasoconstriction in a dose-dependent manner. It is a bronchodilator and reduces vagal-induced bronchoconstriction. You can read the following in Miller’s Anesthesia about sevoflurane respiratory effects - Halothane, isoflurane and sevoflurane have all been shown to relax the upper airway musculature. Inhibition of upper airway muscle activity by isoflurane was independent of dose, and even subanesthetic concentrations totally abolished genioglossus activity. In contrast, sevoflurane-induced changes in upper airway caliber was dose-dependent in children and primarily occurred in an anterior-posterior dimension. In addition to these … Read entire article »

Filed under: General Anesthesia