1. Overwhelming post-splenectomy infection
Review splenic structue and function
Effect of splenectomy
OPSI
Evaluating residual splenic function
Alternative approaches
Prevention of OPSI

2. Splenic function Aristotle postulated that the spleen had no function
Pliny proposed that a congested spleen hindered runners and suggested that the asplenic state led to loss of humor and laughter
Pliny was a first century historian

3. Splenic function
16th century Babylonian Talmud suggested that the spleen produced laughter
Maimonedes postulated that the spleen was not responsible for laughter, but purified the blood stream.
Presumably impure blood suppressed laughter

4. Splenic function Hemofiltration Removal of blood borne organisms
Removal of solid particles from erythrocytes
Destruction of defective or old
Erythrocytes
Platelets
Leukocytes
Spleen vital-can survive without but performs many important functions

5. Splenic function
Detects and responds to foreign substances in the blood- lymphocytes responsible for immune activation
Production of antibodies
Production of opsonins-facilitating phagocytosis and complement activation
Storage pool

9. Blood enters red pulp and passes through fenestrated epithelium to venous sinus - the flow slows allowing macrophages to perform filtration process

10. Many bacteria first need to be opsonized by complement or spleen produced opsonising molecules
Removed efficiently by spleen and liver

11. Encapsulated organisms
Polysaccharide capsule impedes binding of complement
Can be removed in spleen by natural antibodies produced by IgM memory B cells in marginal zone

12. IgM positive memory B cells
Can produce natural antibodies against S. pneumoniae, N. menigitidis, and H . Influenze type b and other encapsulated organisms
Can induce immune responses to infection or vaccination
Reduced numbers in children under 2 years of age
Primarily exist in the spleen
Still some controversy over their exact role
Seem to need the spleen to survive

13. Splenectomy
Well known risk for the development of severe bacterial infections
Reflects the spleens ability to remove circulating particulate matter including bacteria
Important role in the initiation of the humoral immune response

14. Splenectomy Significant decrease in CD4+ T cells-helper cells
Significant decrease in IgM + B cells -memory cells
Related to T-cell independent responses

15. Overwhelming post splenectomy sepsis
First described in 1952 by King and Shumaker-correlating the asplenic state with this rapidly fatal illness
Cohort of children who developed infection after splenectomy caused by encapsulated organisms

16. OPSI Medical emergency
Prodrome-fever, chills, myalgia, headache, vomiting, diarrhea
Septic shock-anuria, hypotension, hypoglycemia, DIC, adrenal hemorrhage, multiorgan failure
Mortality rate is 35-80%, usually within first hours

17. OPSI
Fulminating sepsis, with meningitis or pneumonia, triggered by bacteria,
usually encapsulated organisms
Main organisms:
S pneumoniae %
H influenzae type b
N menigitidis
Group A Streptococcus

18. Other possible organisms
E Coli
Capnocytophaga canimorsus (dog bites)
Enterocococcus sp
Group B Streptococci
Bacteroides sp.
Bartonella sp.

19. Other post-splenectomy infections
Susceptible to infections with intraerythrocytic organisms
Protozoal infections
Tick bites-babesiosis
Fulminating hemolytic febrile illness
Falciparum malaria
Often fatal

20. dx
Infection rate
Death rate
Thalassemia maj
8.2 %
5.1%
Sickle cell
7.3 %
4.8%
Hodgkin’s
4.1%
1.9%
Spherocytosis
3.1%
1.3%
ITP
2.1%
1.2%
Trauma
2.3
1.1%

21. Incidence of overwhelming infection
Increased in all ages
Most episodes occur within first 2 years
Children at greater risk than adults
Those individuals with splenectomy for hematologic conditions at higher risk
Post traumatic splenectomy less risk may be secondary to splenosis

22. Treatment Third generation cephalosporin Plus gentamycin
Cefotaxime or Ceftriaxone
Plus gentamycin
Or Ciprofloxin (for possible urinary or GI source
Or Vancomycin (for possible resistance to penicillin)
Usual source not always identified, includes meningitis or pneumonia in 50% of patients otherwise thought to be nasopharyngeal origin

23. Splenectomy
Increasing awareness of OPSI has led to more conservative approach
guidelines for postraumatic splenectomy is only indicated for patients who are:
Hemodynamically unstable
Have lost more than 1000 cc ‘s of blood
Have required two or more units of PRBC’s
Active and uncontrolled bleeding

24. Spleen saving techniques
Splenorrhaphy
Partial splenectomy
Autotransplantation –investigations inconclusive
Both result in normal immune function

25. Non-operative management
Upadhyaya and Simpson 1968
First case controlled study of non operative vs operative management of children with blunt splenic trauma
Results: isolated splenic injuries could be safely treated without surgery in children
Non-operative treatment is now reported to be successful in 90% of isolated splenic injury

26. Adult data National trauma data bank 5 year study on adults
Success 87% among the 90% in which non operative approach was attempted

27. Non operative management
Conservative management with the use of CT follow up and splenic angiographic embolization for hemorrhage control or treatment of pseudoaneurysms
Studies suggest splenic function preserved

28. Evaluating spleen function
Technetium labeled colloid or rbc scintiscan
Howell-Jolly bodies
Detection of pitted erythrocytes

29. Evaluation of spleen function
Measurement of T and B cell subsets
Measurement of post immunization antibody formation
Measurement of IgM anti S pneumoniae response after vaccination is a highly sensitive marker

30. High frequency of splenosis in children with traumatic splenectomy (59%)with
reduction of pitted erythrocytes
Normal levels of pitted erythrocyte counts were found in pts with splenorrhaphy or partial splenectomy
Autotransplantation found to have intermediate levels between normal and splenectomized patients

31. Calculated 30 ml of implanted splenic tissue necessary to provide some protection
Does not seem to guarantee full protection against OPSI

32. Prevention
Education
Patients and family should be instructed to notify their physicians of any acute febrile illness especially if associated with rigor or systemic symptoms
Notify physicians of travel to tropical countries – risk of parasitic infections
Notify physicians of any bites
No consensus for dental prophylaxis

33. Prevention Antibiotics Not evidence based
Patients most likely to benefit:
Children under 5 years of age
Individuals who have had splenectomy within the past year
Individuals with underlying immunodeficiency in addition to splenectomy

34. regimens Children: < 5 years of age: 125mg BID of Penicillin G
>5 years: 250 mg BID of Penicillin G
Adults : not generally recommended
Alternatives: co-trimoxazole or erythromycin
Episodic short-term antibiotics at the time of febrile illnesses

35. Vaccinations
PPV-23-productions of opsonising anticapsular antibodies by T-cell-independedt mechanism
Recommended for children older than 5 years
2 weeks prior to elective surgery
2 weeks post emergency splenectomy
Revaccination after 5 years

36. PPV-23 limitations Limited persistance of antibodies post-vaccination
Not immunogenic under age 2
Increasing age
Infection caused by serotype not in vaccine

37. PCV-7 Conjugate of polysaccharide to a protein More immunogenic
T-lymphocyte dependent response in patients who have immature B cell population
Relevant for patients under 2, or patients who have already undergone splenectomy

38. PCV-13 Offers coverage for additional strains
Includes all seven serotypes that are most frequently involved in antibiotic resistance

39. Pneumoccal vaccine Children less than 2 years – receive
normal immunization schedule
PCV-7 at 2,4,6, and months of age
PPV-23 at 2 years of age
Booster in 5 years
Children 2-5 years of age
PCV-7 x2 , 2 months apart followed in 2 months with PPV-23

40. Pneumococcal vaccine >5 years of age through adults
Single dose 14 days post splenectomy
Booster dose at 5 years

41. Conjugating capsular polysaccharides to pneumococcal surface peptides may offer new therapeutic approach in future

42. Vaccines H influenzae type b for adults and children
Conjugated vaccine
<2 years give routine vaccination schedule
>2 years - single vaccination in adults seems to be sufficient

43. Vaccines N meningitidis
Conventional tetravalent vaccine - little efficacy under 2-3 years of age (T cell independent)
Conjugate vaccine against serogroup C is highly immunogenic in the first few months of life and also in adults
Not yet in suggested immunizations

44. Better markers to assess splenic function and vaccination response after trauma-(even in patients with non-operative management) might improve risk assessment for overwhelming postsplenectomy infection