At the surface of a gas, the pressure force acts perpendicular (at right angle) to the surface.A closely related quantity is the stress tensor σ, which relates the vector force 
  
    
      
        
          F
        
      
    
    {\displaystyle \mathbf {F} }
   to the 
vector area 
  
    
      
        
          A
        
      
    
    {\displaystyle \mathbf {A} }
   via the linear relation 
  
    
      
        
          F
        
        =
        σ
        
          A
        
      
    
    {\displaystyle \mathbf {F} =\sigma \mathbf {A} }
  .
If ineffective, splenectomy should be considered.If refractory to both these therapies, other options include rituximab, danazol, cyclosphosphamide, azathioprine, or ciclosporin. High-dose intravenous immune globulin may be effective in controlling hemolysis, but the benefit is short lived (1–4 weeks), and the therapy is very expensive. See also
List of circulatory system conditions

References
External links
Case report of warm-antibody autoimmune hemolytic anemia with typical laboratory findings. Clinical Cases and Images
The wAIHA Warriors is a 501(c)3 support and advocacy group for caregivers and patients of warm autoimmune hemolytic anemia. www.waihawarriors.org