Home: Anesthetics | General Anesthetics
Most hip surgery is now carried out using a regional anesthetic in conjunction with a light general. Why? Because general anesthetics are expensive and have multiple side effects.
Administration of general anesthesia has two stages: -
In contemporary practice intravenous anesthetics are usually used for induction. Propofol is probably the most widely used. It has replaced the long standing barbiturate agents such as thiopentone because recovery from propofol is faster and has fewer post anesthesia side effects (see below).
Propofol is not an analgesic, so is administered in combination with an opioid such as fentanyl. Generally speaking a patient won't feel pain whilst under a general anesthetic unless the effectiveness of the anesthetia weakens during the procedure. If that happens the opioid is already in place. Fentanyl, and other opioids, also provide excellent post-operative pain relief.
Inhalational induction (fairly rare) is carried out using an agent called sevoflurane which is a non-pungent gas.
Following induction, inhalational anesthetics or intravenous anesthetic agents are administered continuously to maintain an adequate depth of anesthesia - using the same anesthetic drugs as described above.
All patients are given an inhalation mix of nitrous oxide and oxygen (even if the maintenance anesthetic is given intravenously).
Nitrous oxide: in addition to its analgesic effect it also has a weak anesthetic effect. This means that the dosage of the main general anesthetic can be reduced.
Oxygen: makes up about 30 percent of the total inspired mixture. The main role, of course, being to ensure the patient can breathe but importantly it also ensures that the concentration of nitrous oxide is kept within safe limits.
As with any anesthesia there are risks involved (hence all the care that is taken during your preoperative assessment to ensure you are in a fit state to undergo the operation). These risks are increased in patients who have heart disease or a chronic lung condition.
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