if you are asking this about a patient you are providing care for then i as daytonite suggested, check their h&p or progress notes.
if you are asking for the theories of why a patient with tb may be put on bedrest here are some reasons found in case studies.
the short answer:
why they need to be on bedrest--
-- to reduce breathing rate and rest the lungs.
--to allow good lymph flow and enough good antibodies to the apex, or upper area, of the lungs so the antibodies can help cure the tb.
why they need to get up at various times during the day –
-- to allow for good dependant drainage
-- because lying down 24 hrs. a day makes it more difficult to cough up the sputum and if coughed always while lying down then the sputum collects in the bronchial tubes and can become more toxic.
--to reduce chances of increased nervousness and fatique in the patient
cases of tb were more prevalent back in the 40’s and early 50’s and then began to taper off with better drug treatments. you may notice that some of the literature you find on “tb and bed rest” are based on studies done in the 40’s when tb was so prevalent. in more recent years cases have had a rise again and back to a decline. if you do a search online for “tb bed rest” there are many articles based on medical studies of tb and bed rest.
the original theory for care of tb patients was for them to live at a sanatorium in order not to spread their tb to others as well as to get rest and plenty of fresh air. the theory for the rest was that the lungs were injured or sick and with rest the patient’s breathing rate is slowed and the lungs can heal. kind of the same as with a broken leg is casted to mend or a strain or sprain is rested to heal.
in this article the theory for bed rest is explained with more scientific data.
one theory by, peck, was that if the patient has to lie flat and still all the time that it is more difficult to cough up the sputum and the x-rays show poor drainage. also the patients complain of increased nervousness and fatigue. peck found that most patients at bed rest spent most of their time in a supine position and did not get good dependant drainage. also he concluded that while lying down when the patient coughed the sputum was moved into the bronchial tree and caused the patient to become more toxic and develop serious spread of the disease. so the bed rest program was changed to allow frequent changes of position during the day to promote good drainage.
another theory, by, dock, discusses the apical location of pulmonary tuberculosis and how this is affected by patient positioning. dock stated that based on the mean pulmonic arterial pressure that when a patient is standing or sitting up then the apex or upper portion of the lungs have poor lymph flow and then do not get enough good antibodies to help fight the tb. so his theory is that the patient needs to spend a large part of each day in a recumbent, lying down, position. he says it doesn’t mean to be lying flat 24 hrs. a day but when the patient feels strong enough to get up for 10-30 minutes 4-5 times a day.
although i like to refer to more medically credible sources than “ehow” i thought this article on tb was well done and provides a good overview of some of what we learned in nursing school about tb.