Patch Testing for the Evaluation of Metal Hypersensitivity in the Nuss Procedure

Metal implant allergy: A retrospective cohort analysis at a university allergy practice

Background: Concern of metal sensitization in pre- and postsurgical evaluation is growing, with the recent guidelines remaining the criterion standard for consideration of patch testing. Information remains scarce on surgical screening in the groups of patients who reported a history of metal sensitivity versus those with no reported history. Objective: The objective of this study was to assess the utility of patch testing in surgical candidates based on reported metal allergy history. The secondary objective was to evaluate the utility and outcomes in postsurgical patch testing. Methods: Nine hundred and thirty-one patient charts of patients with the diagnosis of "contact dermatitis" who underwent an evaluation at a single allergy clinic site between January 2013 and December 2022 were identified and reviewed as part of a retrospective chart review study. Patients were included in subgroups based on the time of patch testing and history of reported metal allergy. Results: In all, 67 patients underwent patch testing, 10 (14.9%) of whom were surgical candidates without a history of metal sensitivity, 31 (46.2%) of whom were surgical candidates with a history of metal sensitivity, and 26 (38.8%) of whom were postsurgical patients. Twenty-nine (43.3%) of patients had positive patch testing results, with only one (10%) in the presurgical group, 17 (54.8%) in the presurgical with a history of metal sensitivity, and 11 (42.3%) in the postsurgical group. Zero patients in our cohort without metal sensitivity who were undergoing the Nuss procedure had positive reactions on patch testing, whereas two of four (50%) with reported metal sensitivity who were undergoing the Nuss procedure had positive relevant metal reactions. Conclusion: Ambiguity in the utility of patch testing for surgical decision making remains, despite common utilization. Recent guidelines along with coordination of care among the surgeon, allergist, and patient remains the criterion standard of care.

Utility of routine patch testing prior to surgical repair of pectus excavatum: A multidisciplinary experience via retrospective review at a single tertiary care center

BACKGROUND

The Nuss procedure is the only implant procedure in which routine, rather than selective, preoperative patch testing is recommended. This practice has recently been called into question.

OBJECTIVE

To evaluate an updated experience of pre-implant patch testing in patients undergoing the Nuss procedure.

METHODS

A retrospective chart review of Nuss procedures from 2012 through 2020.

RESULTS

Forty-five patients were identified for data collection. From 2012 to 2014, none of the 14 patients were patch tested. From 2015 to 2020, 26 of 31 (83.9%) were patch tested. Of those tested, only 2 had a positive patch test. A hypoallergenic titanium bar was inserted in each case. In total, there were zero bar reactions.

CONCLUSION

The risks of patch testing are extremely small and should be weighed against the serious implications of even one bar allergy when deciding on future guidelines.

Blood metal levels after minimally invasive repair of pectus excavatum

 

OBJECTIVES

Minimally invasive repair of pectus excavatum (MIRPE) is the most popular surgical approach for paediatric patients with pectus excavatum. A substernal stainless still bar is inserted and left in place for 3 years and then removed. Our goal was to investigate blood metal levels after MIRPE and to correlate them with surgical details, such as the numbers of bars and stabilizers and the length of time the bar was in place.

METHODS

Blood levels of iron, chromium, manganese, molybdenum and nickel were analysed in 130 teenagers (108 boys and 22 girls) who had MIRPE using inductively coupled plasma mass spectrometry. A total of 62 patients were operated on using MIRPE (study group) and 68 patients were evaluated at implant time (control group). Differences between the numbers of bars implanted and the presence or absence of stabilizers were also considered.

RESULTS

Significant increases in the levels of abnormal chromium were found in patients in the study group compared with the controls (P = 0.02). When we compared the group of patients with 2 or more bars with the group with 1 bar, the percentage of patients with a value above the threshold increased by 29 (P = 0.05). A significant increase in chromium levels was observed in patients with stabilizers (P = 0.03). Above-threshold levels of molybdenum were found in 5.1% of patients in the control group, but the number was not statistically significant (P = 0.09).

CONCLUSIONS

We demonstrated that stainless steel devices used in MIRPE can elevate blood metal levels in paediatric patients. Moreover, we demonstrated that the use of metal stabilizers is associated with higher metal levels, probably due to increased dispersion.

Metal allergy after the Nuss procedure for pectus excavatum: a review

Minimally invasive repair of pectus excavatum (MIRPE) technique (the Nuss procedure) is a minimally-invasive method that is commonly used in the treatment of pectus excavatum. An allergic reaction to the metal alloy bar that is implanted in the thorax during the procedure is a reported complication. We briefly review current literature concerning epidemiology, mechanisms and research results of allergic reactions after Nuss bar implantation. This allergic reaction occurs in approximately 2.7% of patients and is caused by metals used in the medical implant. The most common symptoms include fever and skin lesions such as allergic dermatitis. Elevated levels of C-reactive protein is a frequent finding in laboratory tests. In order to minimize the risk of such complications, taking a detailed allergy-based medical history and conducting allergy tests, i.e. patch test are required. Allergic reactions can be managed with conservative treatment such as general or topical glucocorticosteroid therapy and antihistamine agents. Severe allergic reactions can be addressed by implant revision, replacement of the steel bar with a titanium substitute or removal of the stabilization at all. Although the risk of an allergic reaction to titanium is smaller it still exists, the titanium substitute is not routinely used due to its higher cost and lesser plasticity which has a negative impact on matching a stabilizing bar during the surgery. Surgeons treating pectus excavatum should remember about the possible allergic reactions after implantation of the metal bar and be familiar with methods of diagnosis and treatment of those complications.

Pediatric allergic contact dermatitis. Part 2: Patch testing series, procedure, and unique scenarios

Patch testing is the criterion standard for diagnosing allergic contact dermatitis. Causative allergens differ between children and adults, necessitating the development of pediatric-specific patch test series. The Pediatric Baseline Series was developed in 2018 through expert consensus and includes relevant pediatric allergens that dermatologists can use in practice. Obstacles in patch testing, such as the need for multiple office visits, length of patch application, and avoidance of sweat and water on the testing area, are particularly challenging for the pediatric population, and several strategies are proposed. Aside from formal patch testing, alternatives like the repeat open application test and empiric allergen avoidance can be helpful in children. The key to management of allergic contact dermatitis is allergen avoidance, with emphasis on the need to properly identify causative allergens. Continued data collection through registries allows for a better understanding of the diagnosis and management of pediatric allergic contact dermatitis.