The association of anti-platelet factor 4/heparin antibodies with early and delayed thromboembolism after cardiac surgery.

Essentials We evaluated antibody status, thromboembolism and survival after cardiac surgery. Positive antibody tests are common - over 50% are seropositive at 30 days. Seropositivity did not increase thromboembolism or impair survival after cardiac surgery. Results show heparin induced thrombocytopenia antibody screening after surgery is not warranted. SUMMARY: Background Heparin-induced thrombocytopenia (HIT) is a prothrombotic response to heparin therapy with platelet-activating, anti-platelet factor 4 (PF4)/heparin antibodies leading to thrombocytopenia associated with thromboembolism. Objective We tested the hypothesis that anti-PF4/heparin antibodies are associated with thromboembolism after cardiac surgery. Methods This multicenter, prospective cohort study collected laboratory and clinical data up to 30 days after surgery and longer-term clinical follow-up data. The primary outcome variable combined new arterial or venous thromboembolic complications (TECs) with all-cause death until 90 days after surgery. Laboratory analyses included platelet counts and anti-PF4/heparin antibody titers (GTI ELISA), with a confirmatory excess heparin step and serotonin release assay. Chi-square testing was used to test the relationship between our outcome and HIT antibody seropositivity. Results Initially, 1021 patients were enrolled between August 2006 and May 2009, and follow-up was completed in December 2014. Seropositivity defined by OD > 0.4 was common, being almost 20% preoperatively, > 30% by discharge, and > 60% by day 30. Death (1.7% within 30 days) or TECs (69 in total) were more likely if the partient was seronegative (OD < 0.4), but positivity defined by OD > 1.0 or including an excess heparin confirmatory step resulted in equal incidence of death or TECs, whether the patient was seronegative or seropositive. Incorporating the serotonin release assay for platelet-activating antibodies did not alter these findings. Conclusions Seropositivity for anti-PF4/heparin antibodies does not increase the risk of death or thromboembolism after cardiac surgery. Screening is not indicated, and seropositivity should only be interpreted in the context of clinical evidence for HIT. TRIAL REGISTRATION: Duke IRB Protocol #00010736.

Attenuation of the tumor-promoting effect of surgery by spinal blockade in rats.

BACKGROUND: The perioperative period is characterized by a state of immunosuppression, which was shown in animal studies to underlie the promotion of tumor metastasis by surgery. As this immunosuppression is partly ascribed to the neuroendocrine stress response, the authors hypothesized that spinal blockade, known to attenuate this response, may reduce the tumor-promoting effect of surgery. METHODS: Fischer-344 rats were subjected to a laparotomy during general halothane anesthesia alone or combined with either systemic morphine (10 mg/kg) or spinal block using bupivacaine (50 microg) with morphine (10 microg). Control groups were either anesthetized or undisturbed. Blood was drawn 5 h after surgery to assess number and activity of natural killer cells, or rats were inoculated intravenously with MADB106 adenocarcinoma cells, which metastasize only to the lungs. Metastatic development was assessed by quantifying lung retention of tumor cells 24 h after inoculation or by counting pulmonary metastases 3 weeks later. RESULTS: Laparotomy conducted during general anesthesia alone increased lung tumor retention up to 17-fold. The addition of spinal block reduced this effect by 70%. The number of metastases increased from 16.7 +/- 10.5 (mean +/- SD) in the control group to 37.2 +/- 24.4 after surgery and was reduced to 10.5 +/- 4.7 during spinal block. Systemic morphine also reduced the effects of surgery, but to a lesser degree. Natural killer cell activity was suppressed to a similar extent by surgery and by anesthesia alone. CONCLUSIONS: The addition of spinal blockade to general halothane anesthesia markedly attenuates the promotion of metastasis by surgery.

Nosocomial acinetobacter meningitis secondary to invasive procedures: report of 25 cases and review.

The medical records of 25 patients with nosocomial meningitis due to Acinetobacter baumannii were retrospectively reviewed. Most cases occurred in the neurosurgical intensive care unit over a 5-year period, with an increased rate during summer. The majority of infections were associated with indwelling ventriculostomy tubes or CSF fistulae in patients receiving antimicrobial therapy. Repeated environmental cultures failed to reveal a source of the microorganism, and control measures had no apparent effect on the outbreak. However, no further cases appeared following a sharply reduced total intake of antibiotics in the neurosurgical department. Forty-one cases of acinetobacter meningitis, secondary to invasive procedures, were found in the English-language literature and were compared with the cases presented. To our knowledge, our series is the largest of acinetobacter meningitis reported hitherto. Although not one of the most common pathogens in hospitals, Acinetobacter constitutes an increasing threat for patients, especially those receiving antimicrobial therapy in intensive care units who are being maintained by various life-support systems.