Use of nitrous oxide is contraindicated in all of the following surgeries except ?
Exentration operation One major problem with N20 is that it will exchange with N2 in any air containing cavity in the body. Moreover, because of their differential blood : gas paition coefficients, nitrous oxide will enter the cavity faster than nitrogen escapes, thereby increasing the volume and/or pressure in the cavity. Examples of air collections that can be expanded by nitrous oxide are : - Pneumothorax - Air embolus - Obstructed middle ear - Obstructed loop of bowel - lntracranial air - A pulmonary (bleep) Nitrous oxide should be avoided in these clinical settings: Now lets move on to the options Nitrous oxide in vitreoretinal surgery The use of nitrous oxide anaesthesia in patients with an intraocular gas bubble is potentially sight threatening. Patients who have vitreoretinal surgery often have a gas bubble deliberately left within the eyes as it helps keep the retina attached while adhesions develop. Filtered room air, Sulfur hexqfluoride and perfluoropropane are the most commonly used gases. By varying the concentration volume and type of gas used, bubbles can be produced that will last upto 70 days before being completely absorbed. If nitrous oxide is administered during this time the bubble will rapidly expand with the risk of retinal and optic nerve ischemia. Nitrous oxide and middle ear surgeries Middle ear cavity is connected to eustachian tube. When nitrous oxide is inhaled in large quantities N20 replaces the N2 in the middle air cavity thereby increasing the pressure in the cavity. After discontinuation of N20 the gas is rapidly reabsorbed from the cavity thus creating negative pressure in the cavity this may cause: ? - Serous otitis media - Disaiculation of stapes - Impaired hearing N20 anaesthesia is hazadrous to hearing iu patients who have previously undergone reconstructive middle ear surgery. Microlaryngeal surgery CO2and (Nd : YAG) lasers are frequently used for microsurgery on the upper airway and trachea. Lasers can ignite materials used in anaesthesia. The CO2 laser can penetrate an endotracheal tube and ignite a fire. Nitrous oxide suppos combustion just like 02 and and may ignite fire.
Cochlear implant
Microlaryngeal surgery
Vitreoretinal surgery
Exentration operation