t
INFECTION PREVENTION & CONTROL
The mechanics of cleaninginstruments
Pawel de Sternberg Stojalowski, founder and managing director at Aseptium, provides a crash course in the mechanics of cleaning complex surgical instruments.
Sixty years ago, a chemical engineer from Henkel, Dr Herbert Sinner, came up with a framework describing critical elements of effective cleaning: mechanical action, chemicals, temperature, and time. Although this concept was proposed for the washing of clothes, it was quickly adopted in other fields of science and industry, including cleaning of surgical instruments. While the concept points out those four critical elements, it also assumes there is a relationship between them. The four elements, like in a pie chart, complete a full circle – Sinner’s Circle. This concept assumes that decreasing effectiveness of one of those elements can be compensated by increasing the role of the others to achieve the same result. Sinner’s Circle identifies the critical elements, but the relationship in the case of surgical instruments’ decontamination is far more complicated. When instruments are manually scrubbed, or flushed, technicians are guided by their eyes to remove contamination they see on instruments, and they continue the task until they see contamination gone.
From a control point of view, it is a closed-loop system where feedback, in this case contamination the technician sees being removed, is continually providing information about the state of the outcome. Typically, washers for surgical instruments do not provide continuous feedback – they are an open-loop system. What this means is that the washer itself will simply execute a cleaning programme without knowing where the contamination is, checking the rate of its removal or the outcome. It can be compared to manually washing the instruments blindfolded. If the technician could not see the contamination on the instruments, they would have to assume the entire instrument is equally dirty with the most difficult type of
The Sinner’s Circle elements become the foundation of identifying critical process variables – mechanics, chemicals, temperature, and time. Out of those, it is the mechanics that is probably the most difficult to develop and control.
SEPTEMBER 2019
contamination they can encounter – the worst-case scenario. They would have to come up with a standardised way of scrubbing, flushing and brushing all around the instrument to ensure every instrument gets completely cleaned every single time. This is, more-or-less, what developing automated cleaning systems, like washer- disinfectors, is all about. The Sinner’s Circle elements become the foundation of identifying critical process variables – mechanics, chemicals, temperature, and time. Out of those, it is the mechanics that are probably the most difficult to develop and control. And here is why.
A crash course in mechanics of washing
Inside the washer, mechanical forces are applied by water which is either sprayed onto the instruments by spray arms or flushed through the hollow channels of directly connected lumens. At the same time, it delivers chemicals to the load that aid mechanical forces by breaking down contamination on the molecular level. The spray arms and lumen flushing need to be considered separately as they are almost entirely independent and need to be considered individually.
WWW.CLINICALSERVICESJOURNAL.COM I 45
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92
