across membranes which sieve molecules, either proteins, electrolytes or water, based on the size of the pores) and the distributed model (which emphasizes the role of capillaries and the solution's ability to increase the number of active capillaries involved in PD). The high concentration of glucose drives the filtration of fluid by osmosis (osmotic UF) from the peritoneal capillaries to the peritoneal cavity. Glucose diffuses rather rapidly from the dialysate to the blood (capillaries). After 4-6 h of the dwell, the glucose osmotic gradient usually becomes too low to allow for further osmotic UF. Therefore, the dialysate will now be reabsorbed from the peritoneal cavity to the capillaries by means of the plasma colloid osmotic pressure, which exceeds the colloid osmotic pressure in the peritoneum by approximately 18-20 mmHg (cf. the Starling mechanism). Lymphatic absorption will also to some extent contribute to the reabsorption of fluid from the peritoneal cavity to the plasma. Patients with a high water permeability (UF-coefficient) of the peritoneal membrane can have an increased reabsorption rate of fluid from the peritoneum by the end of the dwell. The ability to exchange small solutes and fluid in-between the peritoneum and the plasma can be classified as high (fast), low (slow) or intermediate. High transporters tend to diffuse substances well (easily exchanging small molecules between blood and the dialysis fluid, with somewhat improved results with frequent, short-duration dwells such as with APD), while low transporters have a higher UF (due to the slower reabsorption of glucose from the peritoneal cavity, which results in somewhat better results with long-term, high-volume dwells), though in practice either type of transporter can generally be managed through the appropriate use of either APD or CAPD. Though there are several different shapes and sizes of catheters that can be used, different insertion sites, number of cuffs in the catheter and immobilization, there is no evidence to show any advantages in terms of morbidity, mortality or number of infections, though the quality of information is not yet sufficient to allow for firm conclusions. A peritoneal equilibration test may be done to assess a person for peritoneal dialysis by determining the characteristics of the peritoneal membrane mass transport characteristics. Improvised Dialysis Peritoneal dialysis can be improvised in conditions such as combat surgery or disaster relief using surgical catheters and dialysate made from routinely available medical solutions to provide temporary renal replacement for people with no other