Anaphylactic reactions during surgical and medical procedures.

The most common agents that are responsible for intraoperative anaphylaxis are muscle relaxants. However, latex accounts for a significant number of these reactions, and the incidence of intraoperative anaphylaxis caused by latex is increasing. It is now probably the second most important cause of intraoperative anaphylaxis. Following muscle relaxants and latex are probably antibiotics and anesthesia induction agents. Other agents that are responsible include colloids, opioids, and radiocontrast material. However, they account for less than 10% of all reactions. The clinical manifestations of intraoperative reactions differ from those of anaphylactic reactions outside of anesthesia. Cutaneous manifestations are far less common; cardiovascular collapse may be more common. The diagnosis can be made more difficult because patients cannot express symptoms. There is a paucity of cutaneous findings; the patient is draped, and concomitantly administered drugs may alter the manifestations. These additional drugs can also complicate therapy. There are populations who are at-risk for anaphylaxis to latex during surgical procedures: individuals with a genetic predisposition (atopic individuals), individuals with increased previous exposure to latex (eg, anyone who requires chronic bladder care with repeated insertion of latex catheters or chronic indwelling catheters), health care workers who are exposed to latex mainly by inhalation, and possibly patients who have undergone multiple surgical procedures and therefore have been exposed to latex intravascularly and by catheterization on a number of occasions. It has been shown that pretreatment with antihistamines and corticosteroids that are used successfully for the prevention of reactions to radiocontrast material are not as effective in the prevention of anaphylactic reactions to latex. Therefore, the major emphasis has been on prevention. The key elements of prevention include an adequate history, testing for latex allergy in high-risk patients, preadmission measures, and the establishment of a "latex-free environment" while the individual is hospitalized. This is particularly important in the operating and recovery rooms.