Hypotension heparins

If die nitrates are administered witii the antihypertensives, alcohol, calcium channel blockers, or the phe-notiiiazines, there may be an increased hypotensive effect. When nitroglycerin is administered intravenously (IV), die effects of heparin may be decreased. Increased nitrate serum concentrations may occur when the nitrates are administered witii aspirin. 

When given rapidly, protamine causes hypotension due to a decrease in vascular resistance, possibly linked to the release of nitric oxide from endothelium. Flypotension can be minimised by slow administration over 10-15 minutes. Protamine does not affect myocardial contractility. In some patients, systemic hypotension occurs in conjunction with pulmonary hypertension and, in severe cases, right ventricular failure. The mechanism is activation of the complement pathways by the heparin-protamine complex leading to release of thromboxane A2, which mediates pulmonary vasoconstriction. Unlike in anaphylaxis, plasma histamine concentrations are not increased. When this syndrome develops protamine administration should be stopped, and some have recommended giving heparin in an attempt to reduce the size of the heparin-protamine complex. 

Direct effect of heparin therapy Suppression of aldosterone secretion in normal cortical tissue by adenoma with delayed recovery after surgery Selective injury to the renal zona glomerulosa during hypotensive /episodes in criticaUy ... 

The hypotensive effect of heparin in hypertension has characteristics which make it different from other hypotensive agents, and also different from other biological effects of heparin. Keller reported that prolonged treatment with heparin (100 units/kg subcutaneously, three times weekly)... 

Because of hemorrhage risk, check hematocrit and test for blood in stool. Administer with caution to menstruating women, or patients with subacute bacterial endocarditis, severe hypotension, liver disease, or blood dyscrasias. Protamine sulfate inactivates heparin and can be used as an antagonist if severe bleeding occurs. 

Other chemical inducers, such as pyran copolymers, tilorone, diethylaminoethyl dextran, and heparin, also have been used. Tilorone is an effective inducer of interferon in mice, but it is relatively ineffective in humans. Initial use of interferon and its inducers instilled intranasally after rhinovirus exposure was successful in the prevention of respiratory diseases. The clinical success of interferon and its inducers has not yet been established, although they may play a significant role in cell-mediated immunity to viral infections and cancer. Disadvantages of interferon use include unacceptable side effects, such as fever, headache, myalgias, leukopenia, nausea, vomiting, diarrhea, hypotension, alopecia, anorexia, and weight loss. 

C. If the patient is overdosed with an unknown quantity of heparin, then give an empiric dose of 25-50 mg over 15 minutes (to minimize hypotension) and de-tennine the activated partial thromboplastin time (aPTT) after 5-15 minutes and for up to 2-8 hours to detemiine need for additional doses. 

Drug contamination Adverse reactions to heparin contaminated with oversulfated chondroitin sulfate have been evaluated in a US case-control study of patients in dialysis facilities who had signs and symptoms of allergic reactions after 1 November 2007 [122 ]. There were 152 adverse reactions associated with heparin in 113 patients from 13 states from 19 November 2007 to 31 January 2008. The use of heparin manufactured by Baxter Healthcare was the factor most strongly associated with reactions, which occurred in 100% of 21 facilities in which cases were reported versus 4.3% of 23 control facilities. Vials of heparin manufactured by Baxter from facilities that reported reactions contained a contaminant identified as oversulfated chondroitin sulfate. Adverse reactions to the contaminated heparin were often characterized by hypotension, nausea, and shortness of breath within 30 minutes of administration. Of 130 reactions for which information on the heparin lot was available, 128 occurred in a facility that had contaminated heparin on the premises. Of 54 reactions for which the lot number of the heparin was known, 52 occurred after the administration of contaminated heparin. 

Cardiovascular In 242 consecutive patients (mean age 58 years, 193 men) with drug refractory atrial fibrillation who underwent catheter ablation and received protamine immediately after catheter ablation to reverse the effects of heparin, 58 had prior exposure to protamine three developed an adverse reaction to protamine (1.2%), each with profound hypotension [212 ]. 

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