Determining the Infusion Rate of Intravenous Solutions in Drops per Minute

Description

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.

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Description

Specialty

ICD-10