The prognosis for patients with AKI is directly related to the cause of renal failure and, to a great extent, to the presence or absence of preexisting kidney disease (estimated GFR [eGFR] < 60 mL/min), as well as to the duration of renal dysfunction prior to therapeutic intervention.
Not only should you tip your hairdresser, you should also tip the person who washes your hair. Multiply the dollar amount of the bill by 0.15 if the service was good but not exceptional. One way to think of this is that for every dollar your hairdresser charges, you should tip him 15 cents.
Personally I find that the more work is done on my hair and the more it will cost me, the more tips I will leave. A simple haircut might lead to 10-12% (e.g. for a $40 haircut I usually leave $5 extra). On the other hand when my hairdresser has spent several hours on color, highlights and styling, I do tip her better because I know that she deserves it.