Biomedical Engineering Reference
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Fig. 10.2 Boxplots of the
total relaxation due to the
addition of SNP to the Krebs
solution, i.e. a measure for
the vasoregulating capability
10.3 Damage as a Function of the Mechanical Load
The previous section showed that damage can be evaluated quantitatively in multi-
ple ways. This can facilitate a consensus as to how much damage is acceptable for a
certain tissue. However, knowing this limit is only useful if the amount of mechan-
ical load needed to induce this damage is known along with it. Therefore, in the
experimental protocol for defining safety limits for tissue loading, there is a need
for controllable force application and subsequent damage evaluation. This way, an
unambiguous relation can be defined between mechanical loading and damage.
The mechanical load exerted during an experiment can be characterized with re-
spect to location, magnitude, displacement boundary conditions, rate, and duration.
These are all parameters that should be controlled or at least acquired during the
experimental process. Ideally, the load should be applied in vivo , so that the induced
damage can be solely attributed to the loading and not to non-physiological ex vivo
conditions. If subsequent damage quantification requires excision of tissue, undam-
aged control segments should also be excised and tested, to rule out damage due to
the excision process.
To clamp the artery in a controlled way, a hand-held mechanical device, shown in
the top left image of Fig. 10.1 , was designed that allows clamping of a rat abdominal
artery in an in vivo setting to a known force (Famaey et al., 2010 ). By combining this
experimental setup with the previous one, data can be collected regarding the degree
of damage to the vasoregulating capability after different in vivo clamping forces.
This type of data was collected for rat abdominal arteries, as described in Famaey
et al. ( 2010 ). In total, 8 segments clamped at 0.5 N with the custom made clamping
device, 6 segments at 5 N, 6 segments clamped with a typical mosquito clamp and
14 zero load control segments were tested in the functional setup. Figure 10.2 shows
boxplots of the total relaxation due to the addition of SNP to the Krebs solution, i.e.
a measure for the vasoregulating capability. Total relaxation due to SNP is signif-
icantly lower for the mosquito-group and for the 5 N-group compared to the zero
 
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