In his article on the detection, education and management of asplenic and hyposplenic patients in this issue,1 Brigden reviews important information on the role of the spleen and what can be done when this organ is absent or not functioning.
The first task is to identify patients who do not have a functional spleen. Because so many diseases can result in splenic hypofunction, a thorough medical and surgical history is important. A careful examination for abdominal scars may be valuable when a patient is unable to provide a good medical history. Although this is seldom reported, Howell-Jolly bodies are a useful laboratory clue to the diagnosis of hyposplenism or asplenia. Despite concerted efforts by physicians, patients who have undergone splenectomy often are not recognized and followed properly.2,3
It is crucial to review the vaccination records of patients who do not have a functional spleen. Immunization against Haemophilus influenzae and meningococci strains seems reasonable, although a clear benefit has not been documented in adult asplenic patients. The major focus of management, however, should be immunization against Streptococcus pneumoniae, which is responsible for most cases of overwhelming postsplenectomy infection. In unvaccinated asplenic patients, the fatality rate for S. pneumoniae sepsis exceeds 40 percent.4
Pneumococcal vaccination is a timely issue because a more effective conjugated pneumococcal vaccine is now available for use in children. Furthermore, the need for revaccination of adults is receiving considerable attention. The increasing resistance of pneumococci to antibiotics, the waning immunity in the elderly population and the low incidence of adverse effects with the conjugated pneumococcal vaccine may make periodic boosters routine.
With the increase in antibiotic resistance and the introduction of more effective vaccines, antibiotic prophylaxis in asplenic patients and patients with sickle cell disease is being questioned. It appears that antibiotics can have a prompt and dramatic effect on pneumococcal resistance, as is demonstrated by the quick development of resistance in day care centers.5 It is also clear that the prolonged use of antimicrobial agents, or even the use of more potent antibiotics, leads to colonization, if not invasion, by resistant strains.
Overwhelming postsplenectomy infection remains a challenge in emergency medical management. Time is of the essence in treatment, and antibiotics are of questionable value once the cytokine cascade of sepsis and vasculitis has started. The search for immune modulators to interrupt this catastrophic chain of events has begun, although there are as yet no clearly effective inhibitors.6
At present, we rely on physicians to detect and treat patients without a functional spleen and to educate these patients about infection risks and necessary health precautions. So far, the results have not been good. As Brigden1 points out in this issue, physicians must become more vigilant. He has even devised a checklist to encourage recognition of at-risk patients.2
Because patient education by physicians seems to be yielding only limited benefits, some investigators believe that additional systems should be in place to supplement the work of physicians.7 One option is a hospital look-back program for patients who have undergone splenectomy, with follow-up provided to ensure that these patients are vaccinated and know what to do if they develop an infection. Reviewing hospital discharge diagnoses might also be helpful. Other system changes, possibly incorporating administrative and organizational strategies, may be worthwhile, as has been demonstrated by vaccine programs.8
With proper data collection, electronic medical records hold the potential to electronically screen thousands, if not millions, of people for the diagnosis of splenic hypofunction. Software programs should be able to detect the vaccines a patient received and when. A history of splenectomy, related disease, or laboratory findings such as Howell-Jolly bodies could be useful indicators to match against vaccine status. It should then be possible to follow up on vaccination inadequacies and intervene with vaccines and patient education. We can hope to be able to apply this technology soon.