Peripheral Intravenous Infusion of Potassium Chloride: RESULTS

10 Jan
2011

After 36 of the intended 60 patients had been enrolled, an interim analysis was conducted. At that time, 7 patients had discontinued the infusion prematurely because of pain. The interim analysis revealed significant differences in pain severity at the end of all 3 infusion periods between the groups (first infusion p = 0.002, second infusion p = 0.002, and third infusion p = 0.042). Based on these results, the study was halted and the remaining 24 patients were not recruited.

At the interim analysis, a total of 36 patients (12 male, 24 female; mean age 57 years, range 18 to 92 years) had been enrolled and had completed the study. Of the 36 patients, 32 received at least 2 consecutive KCl infusions, and of the 32 patients, 25 received 3 consecutive KCl infusions. There was no pre-existing local pain, tenderness, or phlebitis at the site of the infusion, and mean pain scores at the start of the infusions were about equal (Table 1). cialis soft tabs online

Table 1. Mean Pain Scores for Each Group at Different Times


Pain Scores


Time Point


Group


No. of Patients (M/F)


Mean
(95%
CI)


Range

Time zero

Sterile
water

13

(6/7)

1.00

(1.00-1.00)

1-1

0.9%
NaCl

13

(3/10)

1.00

(1.00-1.00)

1-1

0.45%
NaCl

10

(3/7)

1.30

(0.82-1.78)

1-3

Total

36(

12/24)

1.08

(0.96-1.21)

1-3


Time zero
+ 15 min

Sterile
water

13

(6/7)

5.54

(3.23-7.85)

1-10

0.9% NaCl

13

(3/10)

2.77

(1.23-4.31)

1-8

0.45% NaCl

10

(3/7)

3.20

(1.18-5.22)

1-8

Total

36

(12/24)

3.89

(2.77-5.01)

1-10


End of
1st
infusion

Sterile
water

13

(6/7)

6.08

(4.31-7.85)

1-10

0.9% NaCl

13

(3/10)

2.69

(0.78-4.61)

1-10

0.45% NaCl

10

(3/7)

2.30

(0.95-3.65)

1-5

Total

36(

12/24)

3.81

(2.72-4.89)

1-10


End of
2nd
infusion

Sterile
water

12

(5/7)

7.33

(5.09-9.57)

1-10

0.9% NaCl

10

(2/8)

2.10

(0.06-4.14)

1-10

0.45% NaCl

10

(3/7)

3.10

(1.40-4.80)

1-7

Total

32

(10/22)

4.38

(3.03-5.72)

1-10

End of 3rd
infusion

Sterile
water

10

(5/5)

7.40


(4.53-10.27)

1-10

0.9% NaCl

8

(2/6)

2.63

(0.02-5.23)

1-10

0.45% NaCl

7

(1/6)

4.00

(1.28-6.72)

1-9

Total

25

(8/17)

4.92

(3.29-6.55)

1-10

Mean NRS scores ranging from 1 (no pain) to 10 (worst pain) before the first infusion, at 15 min after the start of the first infusion, and at the end of the first, second, and third infusions are shown in Table 1. Although there was no significant difference in the mean numeric score before the first infusion, at all other assessment time points mean pain scores were higher in the sterile water group (Figures 1 and 2). Comparisons between the sterile water and 0.9% NaCl groups showed significant differences at the end of first (NRS difference 3.33, p = 0.003), second (NRS difference 5.23, p = 0.003) and third (NRS difference 4.77, p = 0.043) infusions. Differences in pain scores between the sterile water group and 0.45% NaCl group were significant only after the first (NRS difference 3.78, p = 0.003) and second (NRS difference 4.23, p = 0.007) infusions; no significant difference was found at the end of the third infusion (NRS difference 3.40, p = 0.07). The pain scores for the 2 saline groups never differed by more than 1.43 NRS divisions and did not show any significant differences at any time points.
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Figure 1. Mean numeric

Figure 1. Mean numeric rating scale (NRS) pain scores (95% confidence intervals [vertical lines]) for all 3 study groups after the first (white bars), second (grey bars), and third (black bars) infusion periods.

The pH of the 3 KCl solutions was the same (5.4 ± 0.1). The osmolality of KCl in sterile water was 170 mmol/kg; in 0.45% NaCl, 309 mmol/kg; and in 0.9% NaCl, 438 mmol/kg. There was no linear relationship between solution osmolality and pain score (r2 = 0.0481) (Figure 3).
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Figure 2. Repeated-measure mean

Figure 2. Repeated-measure mean numeric rating scale (NRS) pain scores in the sterile water injection group, the 0.9% saline group, and the 0.45% saline group before the first infusion (T00), at 15 min after the start of the first infusion (T15), at the end of the first infusion (T01), at the end of second infusion (T02), and at the end of third infusion (T03).

Figure 3. Pain scores

Figure 3. Pain scores (closed diamonds) at the end of the first, second, and third infusions, grouped by the osmolality of the infusion solution: 170 mmol/kg (sterile water), 309 mmol/kg (0.45% saline), and 438 mmol/kg (0.9% saline). The horizontal bars indicate the median pain score for all infusions in each group: 7.5, 2.0, and 1.0, respectively. The dashed line represents the linear regression line for individual pain scores and the solution osmolalities, indicating no significant correlation.

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