There does not appear to be a major difference in washout times between the Aestiva and Aisys anaesthetic machines for a given agent, which suggests that despite the different configuration of the two machines (including a different vaporiser and different absorbent canister), the clearance of gases may be dependent on fresh gas flow and priming concentration.
During our experiment, one Aestiva anaesthetic machine gave significantly prolonged sevoflurane washout times (108 and 111 minutes).
The efficacy of activated charcoal filters has been demonstrated only for the Drager Apollo[R] (GE Healthcare, Chalfont St Giles, Buckinghamshire, UK) and Datex-Ohmeda Aestiva machines (6), but it is not unreasonable to expect that they will be similarly effective with other modern machines--as we found, washout from Aestiva and Aisys machines is broadly similar.
Accelerating the washout of inhalational aesthetics from the Drager Primus Anesthetic Workstation.
We found that the washout duration between studies varied from 4-5 days to 8 weeks.
 found that in patients treated with monotherapy latanoprost for at least 6 months, with most greater than 1 year, experienced a significantly lower IOP of 1.3 mmHg compared to baseline measurements following a 14-day washout period.
This finding highlights the complexity of understanding the true IOP effects of single-agent washout in clinical settings where patients are subject to multiple drug classes.
Of the five articles included in the meta-analysis, all except Kobayashi  showed a return to baseline IOP following a washout of 3 or 4 weeks.
Meta-analysis of existing literature demonstrated that after washout, IOP returned to baseline values, with a maximum of 17% IOP reduction (IOPR%) from baseline occurring at 4weeks after washout.
The analysis reveals that there is no standard for PGA washout in reported studies although 4 weeks appears to be the most common period.
The lingering IOP-lowering effects following an insufficient washout may also influence clinical trials designed to evaluate new drugs and/or devices.
Only five studies had washout IOP as the main outcome measured [14, 19, 22, 23], with only one study  publishing data that could be analyzed for PGAs.