Fig 1.
The setup of the SPT lancet attached to the SENSEBox Electronic von Frey weight transducer.
Table 1.
The mean and coefficient of variation (CV %), calculated as the ratio between the standard deviation and the mean for the four predetermined peak lancet weights; 25 g, 85 g, 135 g and 265 g at the forearm and back.
Data for applied lancet weight are pooled for conditions with saline, 1 mg/mL of histamine and 10 mg/mL of histamine. Notice that the deviation is proportionally higher in the 25 g weight group.
Fig 2.
A) The mean wheal diameters on the forearms for each lancet weight; 25 g, 85 g, 135 g and 265 g. A higher lancet weight significantly increased the sizes of the wheal reactions. B) The mean wheal diameters on the back for each lancet weight; 25 g, 85 g, 135 g and 265 g. A higher lancet weight significantly increased the sizes of the wheal reactions. A significant difference was also observed when comparing the two histamine concentrations: 1 mg/mL and 10 mg/mL. For each condition; n = 20. * = p < 0.05, ** = p < 0.01. Mean ± SEM.
Fig 3.
A) Changes in the mean superficial perfusion on the forearms according to the lancet weights: 25 g, 85 g, 135 g and 265 g. A difference in the mean superficial perfusion was seen from baseline to all the four applied lancet weights. B) On the back a difference in the mean superficial perfusion was seen from baseline to all the four applied lancet weights with both histamine concentrations (1 mg/mL and 10 mg/mL) and from baseline for the lancet weight of 265 g with saline as well. For each condition; n = 20. * = p < 0.05, ** = p < 0.01. Asterisks (*) or (**) placed just above the bars indicates significant difference from baseline superficial skin perfusion. Mean ± SEM.
Fig 4.
The percentage distribution of bleeding incidents in response to individual SPTs when using the four lancet weights; 25 g, 85 g, 135 g and 265 g at A) the arm and B) the back, regardless of the applied solution (saline, 1 mg/mL histamine or 10 mg/mL histamine). A higher lancet weight caused increased incidents of bleeding. C) Peak pain intensity in response to the four lancet weights for both arm and back rated on a coVAS. The peak pain intensity increased significantly with increased weight. Notice that pain during SPT, regardless of weight, remains negligible, i.e. < 8 on a 0–100 VAS (N.B.: discrete x-axis is applied for graph C). For each condition; n = 20. * = p < 0.05, ** = p < 0.01. C) Mean ± SEM.
Fig 5.
A) Shows individual lancet peak weight measurements from four different clinicians (no. 1–4). The horizontal lines denote the arithmetic mean for each individual. B) Shows intra-reliability and inter-reliability (dotted horizontal line) of applied weight expressed as the coefficient of variation (standard deviation expressed as % of the mean) for each of the four testees and between the four testees. CV% = Coefficient of variation (calculated as the ratio between the standard deviation and the mean in %).
Fig 6.
Depicts a suggested mechanical approach to a locked weight device allowing for SPT within a specific predetermined weight.