Several methods have been developed to determine the drops per minute required to deliver a given quantity of infusion solution. The first method was presented as a nomogram which allowed for the increase in drop size as the dropping rate increases.
Method 1
|
mL per minute |
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
drops per mL |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
20 |
20.5 |
41 |
60 |
78 |
96 |
114 |
131 |
147 |
164 |
180 |
196 |
214 |
19 |
20 |
39 |
57 |
75 |
92 |
108 |
125 |
141 |
156 |
171 |
186 |
202 |
18 |
19.5 |
37 |
54 |
71 |
87 |
103 |
119 |
134 |
148 |
163 |
177 |
192 |
17 |
18 |
35 |
52 |
67 |
83 |
98 |
113 |
127 |
141 |
154 |
166 |
180 |
16 |
17.5 |
33 |
49 |
64 |
78 |
92 |
106 |
120 |
133 |
145 |
158 |
170 |
15 |
17 |
32 |
47 |
60 |
74 |
87 |
100 |
113 |
124 |
137 |
148 |
160 |
14 |
15 |
30 |
43 |
56 |
69 |
82 |
94 |
106 |
117 |
128 |
139 |
149 |
13 |
14.5 |
29 |
41 |
53 |
65 |
76 |
87 |
99 |
110 |
120 |
129 |
139 |
(approximated from Abbildung 2, page 11, Jeanneret et al, 1957)
where:
• 1 cubic centimeter = 1 mL
Second degree polynomial equations matching the data:
drops per mL |
(mL per min) ^ 2 |
mL per min |
intercept |
---|---|---|---|
13 |
-0.169456 |
13.463412 |
1.875 |
14 |
-0.18981 |
14.628372 |
0.8636364 |
15 |
-0.169081 |
15.124625 |
2.4318182 |
16 |
-0.18469 |
16.24538 |
1.5340909 |
17 |
-0.222278 |
17.546953 |
0.8181818 |
18 |
-0.17545 |
17.883991 |
1.9659091 |
19 |
-0.193806 |
18.925075 |
1.8181818 |
20 |
-0.168207 |
19.541583 |
2.2159091 |
A line matching the data offers simpler calculations but is less accurate at high drip rates.
drops per mL |
mL per min |
intercept |
---|---|---|
13 |
11.26049 |
7.0161616 |
14 |
12.160839 |
6.6212121 |
15 |
12.926573 |
7.5606061 |
16 |
13.844406 |
7.1363636 |
17 |
14.657343 |
7.5606061 |
18 |
15.603147 |
7.2878788 |
19 |
16.404494 |
7.6969697 |
20 |
17.354895 |
7.3181818 |
Method 2
Based on the formula at the bottom of page 7 (Droste, 1997) and formula 1 page 118 (Jeanneret, 1957):
K =
= 60 / (drops per mL)
drops per minute =
= (infusion volume in mL) / ((infusion duration in hours) * K)
This is related to the drip rate formula in the previous section.
Specialty: Toxicology, Emergency Medicine, Critical Care
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