Leslie C. Thomas, M.D.
Jonathan H. Skerman, B.D.Sc., M.Sc.D., D.Sc.

"Latex Allergy: Another Complication for Anesthesiology" was presented in part as a Scientific and Educational Exhibit at the Annual Meeting of the American Society of Anesthesiologists, Orlando, Florida, October 17-21, 1998. As follows is part two of the summary of the presentation. Part one appeared in the April issue of the NEWSLETTER.

Testing of Patients for Latex Allergy

High-risk patients should be identified and encouraged to undergo latex allergy testing. In addition, there are many questionnaires available to assess exposure history. These include whether contact dermatitis occurs with latex exposure, assessment for aerosol reactions in the presence of latex gloves and any other pertinent history suggestive of latex allergy. Some examples of this include a history of anaphylaxis¹ or intraoperative shock, pruritus or swelling following dental, rectal or pelvic examinations, or swelling/breathing difficulties after blowing up a balloon.²Low-risk patients with a negative clinical history do not require testing, unless there are symptoms specifically related to latex.³

The antigens specifically responsible for sensitization and allergic reactivity remain to be fully identified; it is possible that different varieties of the rubber tree exist, with slightly different proteins. Therefore, no single antigen or panel of standardized antigens currently exists for diagnostic testing.⁴ There are two different types of tests currently used to diagnose latex allergy: skin tests and in vitro tests.^2,4

Skin tests are the most sensitive; however, no standardized latex extract is presently available due to the high number of potentially significant natural rubber latex (NRL) allergens (as the amount of latex in gloves varies widely, so do extracts made from them). The potential for anaphylactic reactions exists, so the test must be performed by a specialist with full resuscitative equipment immediately available. The test is either done by intradermal injection of a small amount of a suspension of allergen, or by a scratch test: a 5 mm scratch on the forearm over which is placed a patch of latex glove. Both tests result in a wheal-and-flare reaction if positive.⁵

A study by Turjanmaa et al.⁶ shows that the highest prevalence of latex allergy, as diagnosed by the skin prick test, is for spina bifida patients who undergo multiple surgical procedures (32-65 percent).

Table 2
Prevalence of Latex Allergy: Diagnosis by Skin Prick Test
Population	Prevalence
High-risk groups
Health care workers
OR nurses	8-11%
Hospital physicians	10%
Hospital employees	7-10%
Multiple surgical procedures
Spina bifida children	32-65%
More than 4 surgeries (non-spina bifida patients)	29%
Other glove-wearing professionals
Hairdressers	10%
Low-risk group
Adult surgical patients	0.1-0.4%
Adapted from Turjanmaa K et al.6Allergy. 1996; 51:593-602.

Results from a recent multicenter latex skin testing study in which individuals were challenged with nonammoniated latex reagent (NAL) showed that the reagent accurately diagnosed latex allergy without causing any immediate adverse reactions. This is particularly important since the United States is the only developed country that does not have a skin test reagent currently available for use in detecting latex allergies.⁷

In vitro tests measure the IgE response in the sera of latex allergic patients. Some IgE assay methods include RAST (radioallergosorbent test), the Immunocap System, and AlaSTAT; while some of these tests have shown sensitivities between 53 and 87 percent, false positives can occur, so any positive result must be correlated with the clinical history.^5,8

There are also provocation tests using latex-rubber-containing products. These involve wearing all or part of a latex glove for a predetermined time and looking for symptom development. A similar technique can also be performed using inhalational exposure to airborne latex particles.⁸

In individuals with a positive skin or serum test and no clinical symptoms, the significance is unknown. A positive test and clinical correlation or a reaction to cross-reactive foods, however, must be regarded as a marker for potential natural rubber or latex reactivity. Individuals who have been confirmed allergic should wear a Medic-Alert bracelet at all times and may want to keep a latex-free emergency medical kit in their homes (and instruct local emergency medical technician services where to find it).

Prophylaxis and Prevention of Allergic Reactions

Some health care providers choose to pretreat known hypersensitive patients with prophylaxis to attenuate any response; however, there have been reports that these medications do not prevent an allergic reaction upon subsequent latex exposure.⁹ Some view prophylaxis as unnecessary if a latex safe environment is maintained. The following example regimens, which were devised and tested for the prevention of radiocontrast media reactions and not antigen-induced mast cell activation, may be useful:³

Adults:

• Methylprednisolone 1mg/kg IV q 6 hours; max dose 60 mg
• Diphenhydramine 1mg/kg IV q 6 hours; max dose 50 mg
• Ranitidine 0.5 mg/kg IV q 6 hours; max dose 150 mg

Children:

• < 1-year-old: none
• 1- to 12-years-old: Prednisone 1mg/kg PO q 6 h; (maximum 40 mg) Hydroxyzine 0.7 mg/kg PO q 6 h; max 50 mg
• 12-years-old to adult: Prednisone 1 mg/kg PO q 6 hours, (maximum 40 mg) Loratadine 10 mg PO hs

Intraoperative Management

1.Remove any latex containing material from room prior to cleaning. Have the operating room (O.R.) cleaned prior to case, including anesthesia machine (2.5 hours of nonuse reduces levels of latex aero-allergens by 96 percent).¹⁰Latex allergy case should be first case done in room. Keep O.R. traffic to a minimum; post sign on door indicating latex-free case.

2.Latex-free cart for anesthesia as well as O.R.

3.Exclusive use of latex-free gloves.

4.IVF: use stopcocks for injection; injection ports are made of latex and should not be used (one might want to tape over them).

5.When initiating IV access, use latex-free tourniquet.

6.Central venous access and intra-arterial access: need to check with each component in each kit; many of the syringe plungers contain latex as well as the heplock caps; most pulmonary artery catheter balloons contain latex. There is a latex-free pulmonary artery catheter made by World Medical Corp.¹¹

7.Dress sites with 3M Tegaderm dressing; but open package carefully as the adhesive contains latex and could become an aeroallergen.

8.Have latex-free syringes or use glass syringes.

9.When drawing up medications, many of the rubber stoppers in medication vials contain latex. If possible, remove this stopper and then draw up the medicine. If unable to remove stopper, withdraw the contents with a 0.22 micron filter and use drug immediately. Check with pharmacy to ascertain whether routine or nonroutine drugs are available in vials or ampules that do not contain latex.

10.Pulse oximetry, ECG, noninvasive and invasive blood pressure measurements, respiratory monitoring should be done using latex-free systems. Use a disposable blood pressure cuff (Vital Signs is latex-free); the black hose connecting to the cuff contains latex and should be covered. If unable to obtain latex-free cuff, wrap patient's arm prior to placing cuff.

11.All airway equipment should be latex-free; check with each manufacturer. Pentax fiberoptic scopes are latex-free, as is the Gensia laryngeal mask airway.

12.Epidurals/spinals: check with manufacturer; may need to prep with sterile gauze since some of the prep applicators contain latex. May need to use latex-free or glass syringes. Dress site with 3M Tegaderm and latex-free tape.

13.Latex-Free Products for Cardiac Surgery [Table 2].

14.Stethoscopes: Littman are latex-free except for the cardiac scopes.

15.Prophylaxis: see previous section.

16.Latex allergy should not alter choice of technique; no drugs specifically contraindicated.

17.Since October 1995, all new Ohmeda anesthesia machines are latex-free.¹²

18.Beginning this year, the Food and Drug Administration has mandated that all medical devices be labeled as to their latex content.

19.Be ready to treat anaphylaxis! Have all of the drugs necessary immediately available.

Diagnosis of Latex Anaphylaxis

1.Onset is generally 20-60 minutes after antigen exposure.

2.Presents with hypotension, rash and bronchospasm; hypotension is the most common sign.

3.The primary anaphylactic target organs are cutaneous, gastrointestinal, respiratory and cardiovascular; during regional or general anesthesia, cardiovascular signs predominate.¹³

• Cutaneous: erythema, pruritus, flushing
• Gastrointestinal: nausea, abdominal pain, vomiting and diarrhea
• Respiratory: laryngeal edema, wheezing, shortness of breath, decreased airway compliance
• Cardiovascular: hypotension, tachycardia, MI, dysrhythmias, cardiovascular collapse

4.High levels of serum mast cell tryptase levels during and up to four hours after episode.

5.Will also have increased C3 & C4 levels at 30 minutes, one hour and four hours post episode.

6.Measure blood in EDTA tube; will help confirm anaphylaxis (not specific for latex).

Treatment of Anaphylaxis: Primary Therapy

1.Stop offending allergen immediately.

2.Consider possible routes of latex exposure, including mucosal and inhalational.

3.Remove all latex from surgical field.

4.Maintain airway: 100 percent oxygen; intubate trachea if not already intubated.

5.Maintain blood pressure with crystalloid infusion rapidly; 25-50 cc/kg crystalloid in 5-10 cc/kg boluses. Epinephrine is the mainstay of treatment; 100 µg increments given to support blood pressure; may even need to increase the dose.

6.Discontinue any anesthetic agents.

Treatment of Anaphylaxis: Secondary therapy

• Antihistamine: Diphenhydramine 1mg/kg IV
• Ranitidine 1 mg/kg IV
• Glucocorticoids: Hydrocortisone 5mg/kg initially, then 2.5 mg/kg q 4-6 hours (helps prevent late phase reactions, no immediate effects) or methylprednisolone 1mg/kg initially, then 0.8 mg/kg q 4-6 hours
• Aminophylline: 5-6 mg/kg load; 0.4 to 0.9 mg/kg/hr; check blood level; persistent bronchospasm
• Inhaled ß2 agonist
• Continuous catecholamine infusion:
• 0.02-0.05 µg/kg/min (2-4 µg/min)
• 0.05 µg/kg/min (2-4 µg/min)
• 5-20 µg/kg/min
• Administer sodium bicarbonate: 0.5-1 mg/kg initially, titrate according to ABGs¹³

Summary

As anesthesiologists, we come into contact with latex on a daily basis, and our risk for becoming sensitized is high. By limiting or avoiding altogether our contact with latex antigens, we hope to reduce sensitization and its resultant problems, which usually lead to decreased function in the workplace. Since it is almost impossible, however, to make an operating room latex-free, the goal should be to provide a latex-safe environment. At the 1997 ASA Annual Meeting, it was decided "that a Committee of the President's choice be asked to formulate and publish recommendations for practice which would protect patients and limit anesthesiologists' exposure to latex."¹⁴

This ASA committee, having worked diligently for the past year under the chairship of Jonathan D. Katz, M.D., of Yale University, is about to release their report. It will be available to ASA members through the ASA Publications Department by mid-1999.

References:

1. Zucker-Pinchoff B, Chandler MJ. Latex anaphylaxis masquerading as fentanyl anaphylaxis: Retraction of a case report. Anesthesiology. 1993; 79:1152-1153.
2. SussmanG, Gold M. Guidelines for the management of latex allergies and safe latex use in health care facilities. Am Coll Allergy Asthma Immunol. 1996.
3. Task Force on Allergic Reactions to Latex. American Academy of Allergy and Immunology. J Allergy Clin Immunol. 1993; 92:16-18.
4. Konrad C, Fieber T, Gerber H, Schuepfer G, Muellner G. The prevalence of latex sensitivity among anesthesiology staff. Anesth Analg. 1997; 84:629-633.
5. PollardRJ, Layon AJ. Latex allergy in the operating room: case report and a brief review of the literature. J Clin Anesth. 1996; 8:161-167.
6. Turjanmaa K, Alenius H, Makinen-Kiljunen S, Reunala T, Palosuo T. Natural rubber latex allergy. Allergy. 1996; 51:593-602.
7. American Latex Allergy Association Newsletter. Milwaukee, WI: American Latex Allergy Association, Inc. 1998; 4:1-13.
8. Fein JA, Selbst SM, Pawlowski NA. Latex allergy in pediatric emergency department personnel. Pediatr Emerg Care. 1996; 12:6-9.
9. Holzman RS. Clinical management of latex-allergic children. Anesth Analg. 1997; 85:529-533.
10. Slater JE. Latex Allergy. J Allergy Clin Immunol. 1994; 94:139-149, quiz 150.
11. JohnsonRF, Lobato EB, Eckard JB. Perioperative management of a patient with latex allergy undergoing heart transplantation. Anesth Analg. 1998; 87:304-305.
12. Mandy S, Rudz D, Sanapati M, Frost EAM. Latex Allergy and the Anesthesiologist. Madison, WI: Datex-Ohmeda. Ohmeda Publication Form No. AN1568, 1996.
13. Longnecker DE, Tinker JH, Morgan GE. Principles and Practice of Anesthesiology, 2^nd ed. St Louis, MO: Mosby-Year Book; 1998; 2:2389-2392.
14. Holzman RS, Katz JD. Occupational latex allergy: The end of the innocence. Anesthesiology. 1998; 89:287-289.

Table 1

Leslie C. Thomas, M.D., is Assistant Professor, Department of Anesthesiology, Louisiana State University Medical College, Shreveport, Louisiana.

Jonathan H. Skerman, B.D.Sc., M.Sc.D., D.Sc., is Professor of Anesthesiology and Professor of Obstetrics and Gynecology, Louisiana State University Medical College, Shreveport, Louisiana.

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