• Identification of the predictive muco-cutaneous signs of perioperative allergic immediate hypersensitivity as assessed by the Ring and Messmer clinical scale [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  muco-cutaneous signs (generalized erythema and/or extensive urticaria and/or angioedema)
• Identification of the predictive heart rate of perioperative allergic immediate hypersensitivity as assessed by the Ring and Messmer clinical scale [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  heart rate (beat/min.)
• Identification of the predictive arterial pressure of perioperative allergic immediate hypersensitivity as assessed by the Ring and Messmer clinical scale [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  arterial pressure (mmHg)
• Identification of the predictive upper gastrointestinal symptoms of perioperative allergic immediate hypersensitivity as assessed by the Ring and Messmer clinical scale [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  digestive signs (vomiting)
• Identification of the predictive lower gastrointestinal symptoms of perioperative allergic immediate hypersensitivity as assessed by the Ring and Messmer clinical scale [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  digestive signs (diarrhea)
• Identification of recurrence of perioperative allergic immediate hypersensitivity as assessed by the Ring and Messmer clinical scale [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  recurrence of symptoms following a symptom-free response

• Identification of the predictive clinical signs of perioperative allergic immediate hypersensitivity [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  muco-cutaneous signs (generalized erythema and/or extensive urticaria and/or angioedema)
• Identification of the predictive clinical signs of perioperative allergic immediate hypersensitivity [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  heart rate (beat/min.)
• Identification of the predictive clinical signs of perioperative allergic immediate hypersensitivity [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  arterial pressure (mmHg)
• Identification of the predictive clinical signs of perioperative allergic immediate hypersensitivity [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  digestive signs (vomiting)
• Identification of the predictive clinical signs of perioperative allergic immediate hypersensitivity [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  digestive signs (diarrhea)
• Identification of the predictive clinical signs of perioperative allergic immediate hypersensitivity [ Time Frame: From date of the perioperative clinical reaction up to 6 hours ]
  recurrence of symptoms following a symptom-free response

• Drugs involved in adverse reactions as assessed by the Ring and Messmer clinical scale [ Time Frame: From date of the perioperative clinical reaction and up to 100 months ]
  To identify the drugs involved in the onset of perioperative allergic clinical reactions and compare our results to those provided in the different international epidemiologic studies regarding perioperative immediate hypersensitivity.
• Negative predictive values of skin tests in allergic and non-allergic patients [ Time Frame: Up to 5 years after the allergologic follow-up ]
  Negative skin-tested agents administered according to the results of allergological follow-up during subsequent anesthetics in allergic and non-allergic patients
• Participants with treatment-related adverse events as assessed by by CTCAE v4.0 and fluid therapy [ Time Frame: Through study completion, an average of 2 years ]
  To identify the number of patients who received fluid therapy (volume, type) in allergic hypersensitivity
• participants with treatment-related adverse events as assessed by CTCAE v4.0 and vasoconstrictive agents [ Time Frame: Through study completion, an average of 2 years ]
  To identify the number of patients who received vasoconstrictive agents (ephedrine, neosynephrine, epinephrine, norepinephrine) and corresponding cumulative doses
• participants with treatment-related adverse events as assessed by CTCAE v4.0 and salbutamol and/or steroids [ Time Frame: Through study completion, an average of 2 years ]
  To identify the number of patients who received salbutamol, steroids and corresponding doses
• Participants with treatment-related adverse events as assessed by CTCAE v4.0 and intensive care unit admission [ Time Frame: Through study completion, an average of 2 years ]
  To identify the number of patients who were admitted in intensive care unit
• Participants with treatment-related adverse events as assessed by CTCAE v4.0 and morbidity [ Time Frame: Through study completion, an average of 2 years ]
  To report the morbidity cases including cardiac and/or renal and/or hepatic and/or neurologic failure(s) after perioperative allergic immediate hypersensitivity
• Participants with treatment-related adverse events as assessed by CTCAE v4.0 and mortality [ Time Frame: Through study completion, an average of 2 years ]
  To report the mortality cases after perioperative allergic immediate hypersensitivity

• Drugs involved in adverse reactions as assessed by the Ring and Messmer clinical scale [ Time Frame: From date of the perioperative clinical reaction and up to 100 months ]
  To identify the drugs involved in the onset of perioperative allergic clinical reactions and compare our results to those provided in the different international epidemiologic studies regarding perioperative immediate hypersensitivity.
• Negative predictive values of skin tests in allergic and non-allergic patients [ Time Frame: Up to 5 years after the allergologic follow-up ]
  Negative skin-tested agents administered according to the results of allergological follow-up during subsequent anesthetics in allergic and non-allergic patients
• Participants with treatment-related adverse events as assessed by by CTCAE v4.0 [ Time Frame: Through study completion, an average of 2 years ]
  To identify the number of patients who received fluid therapy (volume, type) in allergic hypersensitivity
• participants with treatment-related adverse events as assessed by CTCAE v4.0 [ Time Frame: Through study completion, an average of 2 years ]
  To identify the number of patients who received vasoconstrictive agents (ephedrine, neosynephrine, epinephrine, norepinephrine) and corresponding cumulative doses
• participants with treatment-related adverse events as assessed by CTCAE v4.0 [ Time Frame: Through study completion, an average of 2 years ]
  To identify the number of patients who received salbutamol, steroids and corresponding doses
• Participants with treatment-related adverse events as assessed by CTCAE v4.0 [ Time Frame: Through study completion, an average of 2 years ]
  To identify the number of patients who were admitted in intensive care unit
• Participants with treatment-related adverse events as assessed by CTCAE v4.0 [ Time Frame: Through study completion, an average of 2 years ]
  To report the morbidity cases including cardiac and/or renal and/or hepatic and/or neurologic failure(s) after perioperative allergic immediate hypersensitivity
• Participants with treatment-related adverse events as assessed by CTCAE v4.0 [ Time Frame: Through study completion, an average of 2 years ]
  To report the mortality cases after perioperative allergic immediate hypersensitivity

The clinical presentation of perioperative allergic and non-allergic clinical reactions is often considered undistinguishable while the accurate analysis of clinical cases shows striking clinical differences which might be predictive of the etiological diagnosis (allergic versus non-allergic).

The four-step Ring and Messmer clinical scale helps to guide acute management of immediate hypersensitivity accordingly to the clinical presentation although this scale does not take into account the mechanism involved (i.e. allergic versus non-allergic). Non-allergic clinical reactions are usually non-life-threatening and may, sometimes, spontaneously resolve in contrast to allergic reactions which are mainly severe and life-threatening conditions, typically called anaphylaxis.

The cornerstones of anaphylaxis management are fluid therapy and epinephrine. However, poor outcome has been reported as a result of delayed treatment and/or inappropriate management of perioperative anaphylaxis.

The main objectives of this study are to: i) characterize the clinical and paraclinical determinants of IgE-mediated allergy that could be correlated to the ultimate diagnosis; and ii) elaborate a decision-making algorithm for clinical patterns identification of perioperative allergic reactions to guide acute management, thus potentially decreasing the related morbidity and mortality.

The secondary objectives are to: i) suggest a modification of the Ring and Messmer scale according to the phenotypes involved; ii) identify the clinical characteristics of isolated non-allergic bronchospasm; iii) compare the most frequent agents involved in perioperative IgE-mediated allergy to those reported in the international studies; iv) identify the negative predictive values of skin tests in allergic and non-allergic patients; v) compare the therapeutic modalities used to those recommended in the literature; vi) describe the cases of morbidity and mortality and identify the potential risk factors.

The Ring and Messmer scale is used to quote the clinical features occurring in drug- or latex-induced immediate hypersensitivity and has been adapted to the perioperative setting as follows:

Grade I: Muco-cutaneous signs only (generalized erythema and/or extensive urticaria and/or angioedema) Grade II: Mucocutaneous signs, hypotension, tachycardia and/or moderate bronchospasm Grade III: Mucocutaneous signs, cardiovascular collapse, tachycardia or bradycardia, bronchospasm, digestive signs Grade IV: Cardiac arrest Grade V: Death

Perioperative immediate hypersensitivity reaction requires further allergologic assessment.

The allergologic assessment is performed a few weeks after the reaction to confirm or disprove an allergic mechanism behind the reaction (i.e. allergy versus non-allergy), and to identify culprit agent(s) and safe drugs, including suitable alternatives. It is based on the review of the details of the reaction along with histamine and/or tryptase levels and specific Immunoglobulin E levels (when available) and skin tests results.

Plasma histamine and/or tryptase levels and Immunoglobulin E levels are measured at the time of the reaction. Acute tryptase levels are compared to baseline tryptase measured at least 24 hours after the reaction or when the patient is referred for allergological investigation. Skin tests, including prick-tests and intradermal tests, are performed during the allergological assessment.

• Hypersensitivity, Immediate
• Perioperative Period

Inclusion criteria:

• Patients having experienced a perioperative immediate hypersensitivity (including the obstetrical setting) according to one grade of the Ring and Messmer clinical scale, for whom:
• The clinical history is known and has been related to perioperative immediate hypersensitivity;
• The biological assessment including plasma histamine and/or tryptase (and serum IgE when available) was performed after the onset of immediate hypersensitivity according to current guidelines;
• The allergological assessment including skin tests performed by the collaborators of this study was carried out according to current guidelines in surviving patients

Exclusion criteria:

• Patients who decline to be involved in the study