Peri-operative anaphylaxis

Peri-operative anaphylaxis is an important cause for mortality and morbidity associated with anaesthesia. The true incidence is unknown and is most likely under reported. Diagnosis can be difficult, particularly as a number of drugs are given simultaneously and any of these agents can potentially cause anaphylaxis. This review covers the clinical features, differential diagnosis and management of anaphylaxis associated with anaesthesia. The investigations to confirm the clinical suspicion of anaphylaxis and further tests to identify the likely drug(s) are examined. Finally the salient features of common and rare causes including non-drug substances are described.

Cardiovascular pharmacology: new drugs and new indications

This review presents a brief overview of some of the many exciting developments that are taking place in the field of cardiovascular pharmacology. Research continues to progress at a rapid rate, and we can expect many drugs to enter the clinical arena within the next few years. It must be borne in mind, however, that the pharmaceutical industry and hospital budgetary restrictions sometimes limit drug development and occasionally interrupt clinical trials, even before their results have been obtained.

Noncardiogenic pulmonary edema immediately following rapid protamine administration

OBJECTIVE

To report the case of a rare, potentially preventable, immediate noncardiogenic pulmonary edema reaction to the rapid administration of protamine during coronary artery bypass graft (CABG) surgery.

CASE SUMMARY

A 74-year-old white man was administered a 250-mg bolus of protamine sulfate toward the end of CABG surgery to reverse the heparin anticoagulation. Immediately following the administration of protamine, oxygen saturation declined, pink frothy sputum was suctioned from the trachea, and 1500 mL of serous fluid was removed from the airway. The patient was stabilized, but the surgeons were unable to close his chest because of the profound edema. Chest closure occurred on hospital day 6, with discharge from the intensive care unit on hospital day 28.

DISCUSSION

Noncardiogenic pulmonary edema is a rare adverse event that occurs in 0.2% of cardiopulmonary bypass patients, with mortality rates approaching 30%. Complement activation or direct pharmacologic release of histamine by high concentrations of protamine is the suspected cause. High concentrations of protamine in the lungs may directly release histamine, with significant vasodilating effects.

CONCLUSIONS

Immediate reversal of heparin anticoagulation with protamine is necessary to control bleeding; however, rapid protamine injection can be associated with life-threatening pulmonary edema. Slower, cautious administration and accurate calculation of protamine doses may prevent such an event.

Recent experiences with hexadimethrine for neutralizing heparin after cardiopulmonary bypass

Hexadimethrine bromide was used for the neutralization of heparin during cardiac surgery in the late 1950s. For some years, this institution has used it for patients who may be allergic to protamine. In view of the recent renewal of interest in hexadimethrine, we present four cases outlining its use during cardiac procedures in such patients. Other drugs for reversing the action of heparin such as heparinase or platelet factor IV are not yet widely available.

Heparin neutralization with methylene blue, hexadimethrine, or vancomycin after cardiopulmonary bypass

There are no clinically available alternatives for reversing heparin in protamine-allergic patients. This study examined the ability of methylene blue, hexadimethrine, and vancomycin to reverse circulating heparin so that these compounds can be carefully examined in future placebo-controlled studies in humans. Heparin activity in blood obtained from extracorporeal circuits was reversed by adding protamine (13.5, 27.0, 81.1, 135.1, and 270.3 micrograms/mL), methylene blue (13.5, 27.0, 135.1, 202.7, 270.3, 337.8, 405.4, 473.0, 540.5, and 810.8 micrograms/mL), hexadimethrine (6.8, 13.5, 20.3, 27.0, 81.1, and 135.1 micrograms/mL), or vancomycin (13.5, 27.0, 135.1, 270.3, 540.5, and 810.8 micrograms/mL), and activated clotting times (ACTs) were measured with kaolin (n = 18). Heparinase-ACT was obtained to determine complete reversal. Heparin concentrations were 3.3 +/- 0.3 U/mL with ACT values of 485 +/- 97 s. The ACT at a protamine concentration of 81.1 micrograms/mL and at hexadimethrine concentrations of 81.1 and 135.1 micrograms/mL was not statistically different from heparinase-ACT; however, methylene blue or vancomycin did not reverse the anticoagulation at any concentrations. Hexadimethrine can reverse heparin-induced anticoagulation after cardiopulmonary bypass as well as protamine, although methylene blue or vancomycin did not neutralize heparin in vitro.

Nitric oxide inhibition attenuates systemic hypotension produced by protamine

BACKGROUND

Protamine reversal of heparin anticoagulation often causes systemic hypotension, and in vitro studies suggest that this may be mediated by release of nitric oxide from the endothelium. The present investigations were designed to evaluate the direct myocardial effects of protamine and to determine in vivo whether nitric oxide inhibition can prevent hypotension during protamine infusion.

METHODS/RESULTS

Protamine sulfate (50 microg/ml) was added to perfusate of eight isolated rabbit heart preparations; in six other preparations, a similar concentration of prolamine was added to heparinized (5 U/ml) Krebs perfusate. Left ventricular developed pressure, maximum rate of pressure rise, and heart rate declined significantly (p < 0.01) in hearts exposed to protamine only (65.0% +/- 6.6%, 55.5% +/- 6.0%, and 87.6% +/- 2.5% of baseline, respectively), whereas protamine added to heparinized perfusate caused little change in developed pressure, maximum rate of pressure rise, and heart rate (85.3% +/- 5.4%, 84.9% +/- 5.5%, and 98.8% +/- 1.6%). To study systemic effects of protamine, we measured hemodynamic parameters in 12 heparinized dogs (150 U/kg). During protamine infusion (1.5 mg/kg intravenously over 30 seconds), mean blood pressure decreased by 46% +/- 7% from baseline (P < 0.05), cardiac output decreased by 38% +/- 4% (p < 0.05), and systemic vascular resistance decreased bv by 14& +/- 9%. After hemodynamic stabilization, Ng-monomethyl-L-arginine (2 mg/kg), a competitive inhibitor of nitric oxide synthesis, was administered to six dogs, and methylene blue (2 mg/kg), an inhibitor of cyclic guanosine monophosphate synthesis, was administered to the remaining six dogs. After treatment with Ng-monomethyl-L-arginine and methylene blue, the second infusion of protamine sulfate caused no significant change in blood pressure or cardiac output. In an additional six dogs, Ng-monomethyl-L-arginine pretreatment (5 mg/kg) blocked the effects of the first dose of protamine. The effect of Ng-monomethyl-L-arginine could be reversed by the addition of (6 mg/kg) L-arginine but not D-arginine.

CONCLUSIONS

Protamine-heparin complex does not cause direct myocardial depression but does lead to severe hypotension in vivo. The finding that hypotension can be blocked by inhibitors of the nitric oxide pathway confirms previous in vitro studies indicating that the effects of protamine are mediated, in part, by the vascular endothelium. Further, these studies suggest a novel approach to prevention of hemodynamic complications caused by heparin reversal after cardiopulmonary bypass.

Reversible inhibition by protamine of human synovial and rabbit platelet secretory phospholipase A2

We investigated the effects of protamine on the release and the activity of 14 kDa type II phospholipase A2 (sPLA2). Protamine blocks both release and activity of sPLA2 from thrombin-stimulated platelets in a concentration-dependent manner. Heparin, an anionic sulfate polysaccharide which has a high affinity for this enzyme, has no inhibitory effect on sPLA2 by itself but it is able to reverse the inhibitory effect of protamine. The liberation by thrombin of platelet factor 4, an alpha-granule constituent, unlike to that of ATP stored in dense bodies, was suppressed by protamine. Platelet aggregation, determined in parallel, was not affected by protamine. Also, protamine did not inhibit platelet arachidonic acid liberation, which is mainly produced by cytosolic PLA2. The non-proteinaceous polycationic hexadimethrine and acidic protein casein failed to inhibit platelet sPLA2 activity. By contrast, the basic polypeptides poly(L-arginine) and poly(L-lysine) potently inhibited sPLA2 activity, indicating the important role of basic amino acids in the inhibitory effect evoked by protamine. Activities of the human recombinant sPLA2 and the unpurified synovial enzyme of patients with rheumatoid arthritis were also inhibited by the same range of protamine, poly(L-arginine) and poly(L-lysine) concentrations. Our results demonstrate that protamine, unlike heparin, blocks platelet sPLA2 release and exerts a reversible inhibitory effect on its activity, probably through the interaction of basic amino acids with the enzyme.

Single doses of intravenous protamine result in the formation of protamine-specific IgE and IgG antibodies

BACKGROUND

Protamine reactions are a well-recognized and serious complication of intravenous protamine administration. IgE-mediated anaphylaxis occurs after initial sensitization and subsequent re-exposure to antigens. Subcutaneous protamine in insulin preparations is associated with protamine-specific IgE and IgG antibody production. In contrast, the influence of intravenous protamine administration on protamine-specific IgE and IgG antibody formation has never been investigated.

METHODS

Sera from 93 patients were analyzed for protamine-specific IgE and IgG antibodies both before and 4 to 6 weeks after exposure to single doses of intravenous protamine. Specific clinical variables were assessed by univariate and multivariate analyses to determine independent predictors of protamine-specific antibody production.

RESULTS

In patients who were previously seronegative, intravenous protamine administration resulted in protamine-specific IgE and IgG antibody production in 17 of 93 (18%) and 15 of 93 (16%) patients, respectively. As determined by multivariate analysis, male gender (p = 0.06) and insulin-dependent diabetes mellitus (p = 0.002) were associated with protamine-specific IgG but not IgE antibody production.

CONCLUSION

Single-dose intravenous protamine resulted in protamine-specific IgE and/or IgG antibody production in 26 of 93 (28%) of patients. Seroconversion was associated with male gender and insulin-dependent diabetes mellitus. Patients responding immunologically to protamine may be at increased risk for experiencing reactions on subsequent exposure.

Effective and less toxic reversal of low-molecular weight heparin anticoagulation by a designer variant of protamine

PURPOSE

This investigation assessed protamine reversal of heparin anticoagulation by formation of a protamine-heparin alpha-helix by use of a new designer-variant protamine [+18BE] that was made from an existing protamine variant [+18B] whose non-alpha-helix-forming amino acid proline (P) was replaced by an alpha-helix-forming glutamic acid (E). The rate of administration of the new [+18BE] variant protamine on efficacy and toxicity in comparison to that of [+21] standard protamine and [+18B] was also studied.

METHODS

Acetyl-EAA(K2A2K2A)4K2-Amide [+18BE] was administered intravenously in a 1:1 dose to low-molecular-weight heparin (LMWH)-anticoagulated (intravenous 150 IU antifactor Xa/kg) dogs over 10 seconds or 3 minutes (n = 7, each group). Reversal efficacy was documented by measuring activated clotting time, thrombin clotting time, antifactor Xa, and antifactor IIa. Toxicity was defined by measuring systemic blood pressure, heart rate, cardiac output, pulmonary artery pressure, and oxygen consumption. Measurements were made at baseline, after administration of LMWH, before its reversal, and for 30 minutes thereafter. Results were compared with those after LMWH reversal with [+21] standard protamine and the [+18B] variant. A total toxicity score (TTS) was calculated for each compound from maximal declines in blood pressure, heart rate, cardiac output, and oxygen consumption.

RESULTS

LMWH anticoagulation reversal was significantly (p < 0.01) less toxic over 10 seconds and 3 minutes with the [+18BE] designer variant (TTS -2.3, -2.2) compared with the [+21] standard protamine (TTS -6.4, -7.2). Percent LMWH reversal at 3 minutes revealed [+18BE] to have antifactor Xa activity as high as 91%, compared with 68% for protamine [+21], when given over 3 minutes (p < 0.05).

CONCLUSIONS

This investigation documents that a new designer variant of protamine [+18BE] has superior efficacy compared with [+21] standard protamine for reversal of LMWH anticoagulation and that this occurs with a highly favorable toxicity profile.

Drug-induced pulmonary disease

Drug-induced disease of any system or organ can be associated with high morbidity and mortality, and it is tremendously costly to the health care of our country. More than 100 medications are known to affect the lungs adversely, including the airways in the form of cough and asthma, the interstitium with interstitial pneumonitis and noncardiac pulmonary edema, and the pleura with pleural effusions. Patients commonly do not even know what medications they are taking, do not bring them to the physician's office for identification, and usually do not relate over-the-counter medications with any problems they have. They assume that all nonprescription drugs are safe. Patients also believe that if they are taking prescription medications at their discretion, meaning on an as-needed basis, then these medications are also not important. This situation stresses just how imperative it is for the physician to take an accurate drug history in all patients seen with unexplained medical situations. Cardiovascular drugs that most commonly produce a pulmonary abnormality are amiodarone, the angiotensin-converting enzyme inhibitors, and beta-blockers. Pulmonary complications will develop in 6% of patients taking amiodarone and 15% taking angiotensin-converting enzyme inhibitors, with the former associated with interstitial pneumonitis that can be fatal and the latter associated with an irritating cough that is not associated with any pathologic or physiologic sequelae of consequence. The beta-blockers can aggravate obstructive lung disease in any patient taking them. Of the antiinflammatory agents, acetylsalicyclic acid can produce several different airway and parenchymal complications, including aggrevation of asthma in up to 5% of patients with asthma, a noncardiac pulmonary edema when levels exceed 40 mg/dl, and a pseudosepsis syndrome. More than 200 products contain aspirin. Low-dose methotrexate is proving to be a problem because granulomatous interstitial pneumonitis develops in 5% of those patients receiving it. This condition occurs most often in patients receiving the drug for rheumatoid arthritis, but it has been reported in a few patients receiving it for refractory asthma. Chemotherapeutic drug-induced lung disease is almost always associated with fever, thus mimicking opportunistic infection, which is the most common cause of pulmonary complications in the immunocompromised host. However, in 10% to 15% of patients, the pulmonary infiltrate is due to an adverse effect from a chemotherapeutic agent. This complication is frequently fatal even when recognized early.(ABSTRACT TRUNCATED AT 400 WORDS)

Heparin and protamine use in peripheral vascular surgery: a comparison between surgeons of the Society for Vascular Surgery and the European Society for Vascular Surgery

It was the intent of this study to document, in general, the patterns and complications of heparin and protamine usage during carotid endarterectomy, aortic and femoral-popliteal-tibial reconstructions for occlusive disease, elective and emergent abdominal aortic aneurysmectomy, thromboembolectomy, and dialysis arteriovenous (AV) fistula placement by surgeons from North America and Europe. All vascular surgeons from the Society for Vascular Surgery (SVS) and the European Society for Vascular Surgery (ESVS) were surveyed by a voluntary, self-reported questionnaire. Six hundred and forty-six completed questionnaires (284 from SVS and 362 from ESVS), representing a 62% response rate, were returned for evaluation. Systemic and regional administration of heparin was common during vascular procedures performed by both SVS and ESVS surgeons. Use of protamine to reverse heparin anticoagulation varied among SVS and ESVS surgeons, respectively, during: carotid endarterectomy (54% vs. 26%, p < 0.01), elective aortic reconstruction for occlusive disease (58% vs. 23%, p < 0.001), elective aortic reconstruction for abdominal aortic aneurysm (63% vs. 27%, p < 0.001), and femoral-popliteal-tibial reconstruction (44% vs. 15%, p < 0.001). Adverse reactions to protamine among the 25,219 and 12,902 cases reported from SVS and ESVS surgeons, respectively, included: hypotension (1209 and 495 cases), pulmonary artery hypertension (65 and eight cases), anaphylaxis (52 and 10 cases), and death (seven and two cases). These adverse responses accounted for 5.3% and 4.0% of the SVS and ESVS cases, respectively. Although this study is subject to the known limitations of a retrospective survey, it is clear that heparin use is common. Protamine reversal of heparin anticoagulation is more common in North America.(ABSTRACT TRUNCATED AT 250 WORDS)

Granulomatous hypersensitivity to protamine as a complication of insulin therapy

A patient is described who developed a granulomatous skin reaction to injections of protamine-insulin for the treatment of her diabetes mellitus. By means of skin testing it was shown that this reaction was caused by protamine. No adverse effects were seen when she was injected with insulin which did not contain protamine.

Drug allergy

Although allergic drug reactions are just one type of adverse reaction to medications, they are clinically very important because of the morbidity and mortality they cause. An ever-expanding pharmacopeia increases the potential for allergic drug reactions. An understanding of the types of allergic drug reactions, their immunopathologic mechanisms, and the most likely medications involved; an approach to determine the drug responsible for the reaction; and ways to prevent future allergic drug reactions are important features in minimizing patient morbidity.

Allergy to protamine

Recent advances in medicine, such as cardiac catheterization, phoresis, dialysis, and cardiopulmonary bypass technology, have increased the need for heparin anticoagulation. To antagonize heparin's effect and prevent hemorrhagic complications after the procedure, protamine has likewise been used more frequently. With its increased use have come increased reports of adverse protamine reactions consisting of rash, urticaria, elevation of pulmonary artery pressure, systemic hypotension, and, at times, death. The elevation of pulmonary artery pressure, which appears to be a rather common occurrence in animals, may be an isolated finding without clinical consequences in humans. However, this pulmonary vasoconstriction may, when severe, lead to acute right-sided heart failure and systemic hypotension. Other protamine reactions involve a decrease in systemic vascular resistance and systemic hypotension without changes in pulmonary artery pressure. Causes of acute protamine reactions may involve the generation of anaphyatoxins and prostanoids either from protamine-heparin complexes or complement-fixing antiprotamine IgG antibodies, from inhibition of plasma Carboxypeptidase N, from crosslinking of cell-surface antiprotamine IgE on mast cells and basophils with subsequent mediator release, or from potentiation of IgE-mediated release of histamine through a polycationin-recognition site. Although we have come a long way in understanding the mechanisms by which protamine can cause its ill effects in humans, more work is clearly needed to define, in prospective studies, the incidence of and risk factors for protamine reactions in various patient groups, and to delineate more clearly which mechanisms are involved in each clinical type of acute protamine reaction. Hopefully, this will lead to strategies and protamine alternatives that will prevent or diminish, in frequency or severity, adverse protamine reactions. Alternatively, a clearer picture of the risk factors important for protamine reactions and the predictive value of diagnostic tests (e.g., protamine IgE antibody) can also minimize the clinical impact of this increasingly common adverse event.

Protamine allergy reactions during cardiac catheterization and cardiac surgery: risk in patients taking protamine-insulin preparations

Protamine insulin use may immunologically sensitize patients to protamine, leading to anaphylactoid reactions upon subsequent exposure to protamine sulfate during cardiac catheterization or cardiovascular surgery. The risk of such reactions in protamine insulin-dependent patients is uncertain. One catheterization study reported a 50-fold greater risk while a second showed no increased risk! To clarify the risk, the records of 7,750 cardiac catheterization procedures between 1984 and 1987 were analyzed for presence of NPH or PZI insulin use, protamine administration, and any complications or adverse reactions. Protamine was administered in 3,341/7,750 procedures (43%), including 171 in diabetics receiving NPH insulin. Adverse reactions to protamine occurred in 2/3, 170 noninsulin patients, 0.06%, and adverse reactions due to probable NPH insulin sensitization occurred in 1/171, 0.6%, of NPH diabetics, p = .034. Meta-analysis of risk showed an odds ratio of 7.96 for the NPH diabetic patients, and combining these results with the other large series in the literature (269 NPH diabetics total) showed an odds ratio of 4.19 compared to a non-NPH insulin group. Meta-analysis of the surgical literature showed the risk in surgical patients to be 2.1% in NPH patients versus 0.12% with no NPH, with an odds ratio of 15.52. The greater incidence in surgical patients may be due to protamine sensitization at prior catheterization and to the larger dose of protamine administered to surgical patients.

Neutralization of low molecular weight heparin by polybrene prevents thromboxane release and severe pulmonary hypertension in awake sheep

Protamine reversal of heparin anticoagulation in patients is occasionally associated with life-threatening acute pulmonary hypertension. In a sheep model, we evaluated the effect on this adverse cardiopulmonary reaction of modifying the type of heparin (low molecular weight heparin compared with unfractionated heparin) and the type of heparin antagonist (polybrene compared with protamine). Protamine reversal of low molecular weight heparin (LMWH) and polybrene reversal of unfractionated heparin induced more than a 10-fold increase of plasma thromboxane B2 levels, a threefold increase of pulmonary vascular resistance and pulmonary artery pressure, and a 25% decrease of PaO2. A similar adverse reaction followed protamine reversal of conventional unfractionated heparin. However, with polybrene (1 mg/kg) reversal of LMWH (1 mg/kg), we measured neither pulmonary hypertension (pulmonary artery pressure was 22.6 +/- 3.6 mm Hg at 1 minute after polybrene reversal of LMWH compared with 47.9 +/- 4.2 mm Hg after protamine reversal of unfractionated heparin, p less than 0.005 groups differ), hypoxemia (PaO2 was unchanged 2 minutes after polybrene compared with a decrease of 26 mm Hg 2 minutes after protamine, p less than 0.05), nor acute release of thromboxane into arterial plasma (thromboxane B2 was 0.2 +/- 0.1 at 1 minute after polybrene compared with 3.7 +/- 1.7 ng/ml at 1 minute after protamine, p less than 0.005). The hemodynamic effects and mediator release were also benign after neutralization of larger doses of LMWH (3 mg/kg) by polybrene (3 mg/kg). The increases of activated clotting time and activated partial thromboplastin time due to both types of heparin were completely reversed with polybrene. Anti-Xa activity increased to more than 3 IU/ml 4 minutes after LMWH anticoagulation (p less than 0.01) but was only partially neutralized by polybrene. Various polyanion-polycation complexes that are formed when heparin anticoagulation is reversed induce thromboxane release and acute pulmonary vasoconstriction in awake sheep. Reversal of LMWH anticoagulation with polybrene does not elicit this adverse reaction.

Serial immunological investigations in a patient who had a life-threatening reaction to intravenous protamine

Reactions to intravenous protamine include rash, urticaria, bronchospasm, hypotension, and/or pulmonary artery pressure elevation. We have previously shown that in diabetic patients receiving daily protamine-insulin injections, the presence of anti-protamine IgE or IgG antibodies are significant risk factors for acute, life-threatening reactions when protamine is given intravenously. To study protamine reactions further, we measured serum anti-protamine IgE and IgG antibody levels, in-vitro basophil histamine release and intracutaneous skin testing to protamine serially in an NPH-insulin dependent diabetic who had a severe, protracted anaphylactic reaction to protamine. At the time of his protamine reaction, his serum contained 8.5 ng/ml of anti-protamine IgE and 1.3 micrograms/ml of anti-protamine IgG antibody. One month following the reaction both anti-protamine IgE and IgG increased to 16 ng/ml (twofold rise) and 90.5 micrograms/ml (70-fold rise), respectively. With time, both anti-protamine IgE and IgG antibody declined. Serial intradermal skin tests using protamine sulphate did not discriminate between the protamine reactor and nine normal control subjects who had no prior exposure nor any demonstrable serum IgE antibody to protamine. In-vitro basophil histamine release to protamine sulphate was inconclusive in discriminating between the protamine reactor and normal control subjects. We postulate that protamine may be an incomplete or univalent antigen that must first combine with a tissue macromolecule or possibly heparin to become a complete multivalent antigen capable of eliciting IgE antibody-dependent mediator release.

Association of protamine IgE and IgG antibodies with life-threatening reactions to intravenous protamine

Life-threatening reactions to intravenous protamine, administered to reverse heparin anticoagulation, have been reported with increasing frequency as a consequence of the escalating use of cardiac catheterization and coronary bypass surgery. Retrospective studies have shown that such reactions are more common in diabetic patients receiving daily subcutaneous injections of protamine-insulin preparations. To determine whether anti-protamine IgE or IgG antibodies might explain the increased risk for protamine reactions among patients with protamine-insulin-dependent diabetes, we conducted a case-control study of 27 patients (diabetic and nondiabetic) who had acute reactions to intravenous protamine and 43 diabetic patients who tolerated protamine without a reaction during diagnostic or surgical procedures. Cases and controls were grouped according to previous exposure to protamine-insulin preparations. In diabetic patients who had received protamine-insulin injections, the presence of serum antiprotamine IgE antibody was a significant risk factor for acute protamine reactions (relative risk, 95; P = 1.0 X 10(-5), as was antiprotamine IgG (relative risk, 38; P = 1.2 X 10(-5). No patients without previous exposure to protamine-insulin injections had serum protamine IgE antibodies. In this group, anti-protamine IgG antibody was a risk factor for protamine reactions (relative risk, 25; P = 0.0062). We conclude that in protamine-insulin-dependent diabetics, the increased risk of serious reactions when intravenous protamine was given appeared to be caused largely by antibody-mediated mechanisms. In nondiabetic subjects, the presence of protamine IgG was significantly associated with an increased risk of acute protamine reactions, although many nondiabetic subjects who had reactions had no IgG antibodies.

Successful cardiopulmonary bypass in diabetics with anaphylactoid reactions to protamine

Two insulin dependent diabetics with previous anaphylactic like (anaphylactoid) reactions to protamine underwent successful cardiopulmonary bypass for coronary artery surgery. Platelet concentrates instead of protamine were used to neutralise their systemic heparinisation. In both cases the anaphylactoid reactions first became apparent after administration of protamine sulphate at the end of cardiac catheterisation. These cases show that adverse reactions to protamine need not be a contraindication to cardiopulmonary bypass and cardiac surgery and emphasise that this condition should be considered in all patients with a history of previous protamine exposure or one which may be associated with anaphylactoid reactions to protamine.

Cardiac arrest following protamine administration

A case report of fatal cardiac arrest following protamine reversal of systemic heparinization during vascular surgery is presented. Patients who have received protamine zinc insulin, NPH insulin, and those with previous exposure to protamine sulphate or allergy to fish are more likely to have a reaction to protamine. Protamine-induced hypotension can be mediated by immunological or non-immunological mechanisms. Several alternative methods of heparin reversal which may avoid similar catastrophes are presented.