Mammalian Physiology '04

Nephrectomy Simulation

An instructive strategy by which to test your depth of understanding of kidney function is to remove the kidneys (nephrectomy) and then track changes that occur over time due to the loss of kidney functions. Below I suggest that you track selected variables picked with an eye towards covering a substantial swath of renal function. These should give you an effective overview of the extent of the resulting derangement. This nephrectomy procedure is patterned closely on one suggested by Drs. Coleman and Randall.**

 

Functional or actual loss of renal mass (see Guyton*) upsets normal homeostasis and thus finally involves many different tissues and body regulatory mechanisms. Such people require vary careful patient management (see Guyton * and below). Loss of renal mass can be simulated in HUMAN by decreasing the parameter REMASS (renal mass) from a normal value of 1.0 (full mass) to various values down to 0.0 (total loss of renal mass). In this case, you will set REMASS to 0.0. Gather data for four days as indicated for the variables listed directly below. You are, of course, not restricted to only these variables.

I. Plasma concentrations and acid-base status


   --------d a y s post- nephrectomy------
 

 Plasma
      concentrations Name DAY 1 DAY 2 DAY 3 DAY 4
 
 Plasma Na+ PNA __________ __________ __________ __________
 
 Plasma K+ PK __________ __________ __________ __________
 

 Blood
      Urea Nitrogen BUN __________ __________ __________ __________
 Bicarbonate BICARB __________ __________ __________ __________
 

 Plamsa
      Protein PPR __________ __________ __________ __________
 

 Plasma
      Osmolarity POSM __________ __________ __________ __________
 Hematocrit HCT __________ __________ __________ __________
 

 blood
      pH pH __________ __________ __________ __________


 Ventilation VENT __________ __________ __________ __________


 Arterial
      PCO2 PCO2A __________ __________ __________ __________


.

1) Be able to account for the disruptions in plasma concentrations and in acid-base balance. (you might compare your results with G fig. 31-9)

2) Do you see evidence of respiratory acid-base compensation? (check VENT & PCO2A or view "Ventilation and Lungs" summary under Charts/Extra data).

 

II. Identify/characterize compartment volume and hemodynamic changes.


 Variable/Parameter Pre-nephrectomy Day 4 post-neph. % Change
 

 Arterial
      Pressure(AP) __________ __________ __________
 Cardiac Output (COL) __________ __________ __________
 

 Peripheral
      resistance(TPR) __________ __________ __________
 Red cell mass (RCM) __________ __________ __________
 

 Plasma
      volume(PV) __________ __________ __________
 Interst. Fluid Volume(IFVL) __________ __________ __________
 

 Total
      Body H2O (BH2OL) __________ __________ __________
 Cell H2O (CELH2O) __________ __________ __________

Try restricting water intake to slow the development of the volume problem. Water intake can be restricted via limiting water intake via food ingestion ( FDH2O)***. Evaluate your degree of success.

 

References
* Guyton and Hall. Textbook of Medical Physiology. 10th edition. W.B. Saunders Co., 2000. Pages 373-376.

**Coleman, Thomas and Randall, James E. Student Manual. HUMAN-80. Microcomputer Version of a Mathematical Model of The Human Body In Health, Disease and During Treatment, April, 1981.

Notes
*** In a soon to be mounted version of the model, water restriction via access to H2OMAX and H2OMIN will be implemented.