Timing of vaccination does not affect antibody response or survival after pneumococcal challenge in splenectomized rats

Laparoscopic surgery for pancreatic neoplasms: the European association for endoscopic surgery clinical consensus conference

BACKGROUND

Introduced more than 20 years ago, laparoscopic pancreatic surgery (LAPS) has not reached a uniform acceptance among HPB surgeons. As a result, there is no consensus regarding its use in patients with pancreatic neoplasms. This study, organized by the European Association for Endoscopic Surgery (EAES), aimed to develop consensus statements and clinical recommendations on the application of LAPS in these patients.

METHODS

An international panel of experts was selected based on their clinical and scientific expertise in laparoscopic and open pancreatic surgery. Each panelist performed a critical appraisal of the literature and prepared evidence-based statements assessed by other panelists during Delphi process. The statements were further discussed during a one-day face-to-face meeting followed by the second round of Delphi. Modified statements were presented at the plenary session of the 24th International Congress of the EAES in Amsterdam and in a web-based survey.

RESULTS

LAPS included laparoscopic distal pancreatectomy (LDP), pancreatoduodenectomy (LPD), enucleation, central pancreatectomy, and ultrasound. In general, LAPS was found to be safe, especially in experienced hands, and also advantageous over an open approach in terms of intraoperative blood loss, postoperative recovery, and quality of life. Eighty-five percent or higher proportion of responders agreed with the majority (69.5%) of statements. However, the evidence is predominantly based on retrospective case-control studies and systematic reviews of these studies, clearly affected by selection bias. Furthermore, no randomized controlled trials (RCTs) have been published to date, although four RCTs are currently underway in Europe.

CONCLUSIONS

LAPS is currently in its development and exploration stages, as defined by the international IDEAL framework for surgical innovation. LDP is feasible and safe, performed in many centers, while LPD is limited to few centers. RCTs and registry studies are essential to proceed with the assessment of LAPS.

Time lapse and comorbidities influence patient knowledge and pursuit of medical care after traumatic splenectomy

BACKGROUND

There is insufficient knowledge of infectious risk in patients after splenectomy; minimal data exists specifically for trauma patients. This study evaluated patient knowledge and practices regarding infection risk after traumatic splenectomy. Our hypothesis was that patients with poor knowledge regarding their asplenic state would be less likely to pursue medical care in the event of an illness than those with good knowledge.

METHODS

Non-randomized, cohort study of all posttraumatic splenectomy patients < or =11 years after injury in 2 rural trauma centers. Patients received a validated questionnaire; weighted responses determined knowledge about infection risks and appropriate follow-up actions.

RESULTS

Fifty-four percent of patients responded to the questionnaire. Overall, 47% of responders were identified as having adequate knowledge regarding infectious risk, and only 28% would pursue appropriate medical care. Of patients with adequate knowledge, 42% were more likely to pursue appropriate care versus 15% of patients with inadequate knowledge (p = 0.06). Patients with adequate knowledge were more likely to receive an annual influenza vaccine (p = 0.03) and contact their provider with fewer symptoms (p = 0.03). Logistic regression revealed significant interactions between knowledge and presence of comorbidities (p = 0.04). Focusing on patients with poor knowledge and absence of comorbidities, none would engage in appropriate action in the event of illness (p < 0.01). A longer time since injury, >3 years, was associated with a diminished likelihood of appropriate action (p = 0.03). The relationship between knowledge and action was not accounted for by other potential confounders.

CONCLUSIONS

Trauma patients retain minimal knowledge about infection risk after splenectomy and are not likely to pursue appropriate medical care. Time since injury negatively influences patient actions. Healthcare providers must be more proactive to develop new strategies in educating these patients, particularly those without comorbidities and those greater than 3 years postsplenectomy.

Experimental infection of rhesus macaques with Streptococcus pneumoniae: a possible model for vaccine assessment

BACKGROUND

We explored the possibility of using normal adult rhesus macaques for the preclinical assessment of safety, immunogenicity, and efficacy of newly developed vaccines against Streptococcus pneumoniae infection of the lung.

METHODS

Our primary objective was to determine whether an intra-bronchial inoculum of at least 10(6)S. pneumoniae colony-forming units, or one as high as 10(8)-10(9) organisms, could detectably survive in rhesus macaques for a period longer than 1-2 weeks. If so, we hypothesized, it would be possible to observe signs of pneumonia commonly observed in humans, and discriminate between vaccinated/protected animals and controls. Infection was detectable in bronchoalveolar lavage fluids 3-5 weeks post-inoculation.

RESULTS

The clinical course of disease mimicked aspects of that of human pneumococcal pneumonia. Signs of inflammation typical of the disease in humans, such as elevated concentrations of neutrophils and of pro-inflammatory cytokines in bronchoalveolar lavage fluids were also observed.

CONCLUSIONS

These findings underscore the utility of this model to assess the safety, immunogenicity, and efficacy of newly developed S. pneumoniae vaccines.

Radiographic characteristics of postinjury splenic autotransplantation: avoiding a diagnostic dilemma

BACKGROUND

Splenic autotransplantation after postinjury splenectomy has been advocated to augment the immune response to infection and prevent overwhelming postsplenectomy sepsis. Postoperative computed tomographic (CT) scans in patients undergoing splenic autotransplantation reveal multiple intra-abdominal fluid collections that may appear similar to abscesses. This presents a diagnostic dilemma. In the past, one of our patients underwent percutaneous drainage of such collections that were sterile, and one patient required operative evacuation of infected implants. The purpose of this study was to determine whether there is a characteristic radiographic appearance of splenic implants, whether this appearance changes with time, and whether implants can be differentiated from abdominal abscesses.

STUDY DESIGN

Patients at our Level I trauma center who underwent operative therapy for splenic injury from January 1995 to May 2002 were identified using our trauma registry. Charts were reviewed and CT scans read in a blinded fashion by a radiologist.

RESULTS

During the study period, 505 patients were admitted for splenic trauma. One hundred forty-five patients (29%) required operative intervention for splenic injuries. Splenorrhaphy was performed in 27 patients and splenectomy was required in 118 patients. Twenty-three patients had splenic autotransplantation into the omentum, of whom 11 underwent postoperative CT scanning for clinical suspicion of intra-abdominal abscess. On average, 2.7 scans were obtained per patient, ranging from 4 to 113 days postoperatively. Imaging revealed low-density fluid collections in the anterior abdomen in 10 of 11 patients. Time-related radiographic changes (early rim enhancement and late shrinkage) of the implants were noted, but splenic implants lacked surrounding omental fat stranding or other inflammatory changes typical of an abscess. The patient with infected splenic implants had air bubbles within the fluid collections, a characteristic finding of an abscess.

CONCLUSION

Autotransplanted splenic tissue may resemble an abscess on CT scanning, but splenic implants have distinct and time-related characteristic findings. Recognition of these unique features may allow differentiation of a splenic implant from an abscess, thus avoiding unwarranted intervention.

Delayed Vaccination Does Not Improve Antibody Responses in Splenectomized Rats Experiencing Hypovolemic Shock

Delayed vaccination after splenectomy has been shown to increase the antibody response in normotensive rats. The purpose of this experiment was to study the effect of timing of vaccination on antibody responses in rats undergoing splenectomy and experiencing hypovolemic shock. Sixty male Sprague-Dawley rats weighing 250 to 400 g underwent either a sham abdominal surgery or splenectomy after a 30-minute period of controlled hypovolemic shock. All rats then received pneumococcal vaccinations one day, 7 days, or 28 days postoperatively. Antibody levels were determined by enzyme-linked immunosorbent assay 3 weeks after vaccination. Results were compared by analysis of variance. Animals vaccinated one day postoperatively had similar or higher antibody responses than did rats receiving delayed vaccinations after 7 or 28 days. These results were similar for immunoglobulins G and M and more importantly were consistent for animals undergoing splenectomy and sham operations. Delayed vaccinations failed to improve antibody responses when hypovolemic shock preceded splenectomy. We propose that this is the result of complex cytokine responses to hypovolemic shock. These responses have been studied extensively in the setting of septic shock but not in the setting of hypovolemic or hemorrhagic shock.

Improved Antibody Responses to Delayed Pneumococcal Vaccination in Splenectomized Rats

Pneumococcal vaccination following splenectomy is widely used as prophylaxis against overwhelming postsplenectomy infection. There remains controversy however, over the timing of vaccination. We hypothesized that delaying vaccination would increase the antibody response. Pneumococcal vaccinations were given at designated intervals to rats that had undergone either a sham abdominal surgery or splenectomy. Sixty male Sprague-Dawley rats, 250 to 400 g, were divided into three groups for vaccination: I, 1 day postoperatively; II, 7 days postoperatively; and III, 28 days postsplenectomy/sham. Serum antibody levels were then determined by enzyme-linked immunosorbent assay at 5 and 21 days after vaccination. Immunoglobulin (Ig) levels after delayed vaccination at 1 week postoperatively and 1 month postoperatively were significantly higher than levels from rats vaccinated 1 day postoperatively. IgM levels after vaccinations 1 week and 1 month postoperatively were also significantly higher than levels of rats vaccinated 1 day postoperatively (P < 0.05 for both IgG and IgM). On the basis of these results, we conclude that delaying vaccination after splenectomy enhances antibody responses.