Characteristics and outcomes of rapid response team activations for hypotension in orthopaedic patients.

BACKGROUND: Hypotension following orthopaedic surgery has been associated with increased morbidity and mortality. Rapid response teams (RRT) review patients on hospital wards with hypotension. AIM: To evaluate the epidemiology of hypotensive RRT activations in adult orthopaedic patients to identify contributing factors and areas for future quality improvement. METHODS: Timing of RRT activations, presumed causes of hypotension and associated treatments were assessed. RESULTS: Among 963 RRT activations in 605 patients over 3 years, the first calls of 226 of 605 patients were due to hypotension, and 213 (94.2%) of 226 had sufficient data for analysis. The median age was 79 (interquartile range 66-87) years; 58 (27.2%) were male, and comorbidities were common. Most (68%) surgery was emergent, and 75.1% received intraoperative vasopressors for hypotension. Most activations occurred within 24 h of surgery, and hypovolaemia, infection and arrhythmias were common presumed causes. Fluid boluses occurred in 173 (81.2%), and the time between surgery and RRT activation was 10 (4.0-26.5) h. in cases where fluid boluses were given, compared with 33 (15.5-61.5) h. where they were not (P < 0.001). Blood transfusion (30, 14.1%) and withholding of medications were also common. Hospital mortality was 8.5% (18), and 13.6% (29) were admitted to critical care at some stage. In-hospital death was associated with older age, functional dependence, arrhythmia and presumed infection. CONCLUSIONS: Hypotension-related RRT calls in orthopaedic patients are common. Future interventional studies might focus on perioperative fluid therapy and vaso-active medications, as well as withholding of anti-hypertensive medications preoperatively.

The terminal portion of leptospiral immunoglobulin-like protein LigA confers protective immunity against lethal infection in the hamster model of leptospirosis.

Subunit vaccines are a potential intervention strategy against leptospirosis, which is a major public health problem in developing countries and a veterinary disease in livestock and companion animals worldwide. Leptospiral immunoglobulin-like (Lig) proteins are a family of surface-exposed determinants that have Ig-like repeat domains found in virulence factors such as intimin and invasin. We expressed fragments of the repeat domain regions of LigA and LigB from Leptospira interrogans serovar Copenhageni. Immunization of Golden Syrian hamsters with Lig fragments in Freund's adjuvant induced robust antibody responses against recombinant protein and native protein, as detected by ELISA and immunoblot, respectively. A single fragment, LigANI, which corresponds to the six carboxy-terminal Ig-like repeat domains of the LigA molecule, conferred immunoprotection against mortality (67-100%, P<0.05) in hamsters which received a lethal inoculum of L. interrogans serovar Copenhageni. However, immunization with this fragment did not confer sterilizing immunity. These findings indicate that the carboxy-terminal portion of LigA is an immunoprotective domain and may serve as a vaccine candidate for human and veterinary leptospirosis.

Leptospira immunoglobulin-like proteins as a serodiagnostic marker for acute leptospirosis.

There is an urgent need for improved diagnosis of leptospirosis, an emerging infectious disease which imparts a large disease burden in developing countries. We evaluated the use of Leptospira immunoglobulin (Ig)-like (Lig) proteins as a serodiagnostic marker for leptospirosis. Lig proteins have bacterial immunoglobulin-like (Big) tandem repeat domains, a moiety found in virulence factors in other pathogens. Sera from patients identified during urban outbreaks in Brazil reacted strongly with immunoblots of a recombinant fragment comprised of the second to sixth Big domains of LigB from L. interrogans serovar Copenhageni, the principal agent for transmission in this setting. Furthermore, the sera recognized an analogous LigB fragment derived from L. kirschneri serovar Grippotyphosa, a pathogenic serovar which is not endemic to the study area. The immunoblot assay detected anti-LigB IgM antibodies in sera from 92% (95% confidence interval, 85 to 96%) of patients during acute-phase leptospirosis. The assay had a sensitivity of 81% for sera from patients with less than 7 days of illness. Anti-LigB antibodies were found in sera from 57% of the patients who did not have detectable anti-whole-Leptospira responses as detected by IgM enzyme-linked immunosorbent assay and microagglutination test. The specificities of the assay were 93 to 100% and 90 to 97% among sera from healthy individuals and patients with diseases that have clinical presentations that overlap with those of leptospirosis, respectively. These findings indicate that the antibody response to this putative virulence determinant is a sensitive and specific marker for acute infection. The use of this marker may aid the prompt and timely diagnosis required to reduce the high mortality associated with severe forms of the disease.