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Flow rate variance of commonly used IV units
#~ERGENCY METHODS AND TECHNIQUES
F iow rate variance
of commonly used IV units Robert H. Dalley, MD* Los Angeles, California
Twenty commonly used Intravenous needles and catheters were compared ~llh respect to rates of flow of fluid through them. Large differences were en¢0untered even for units apparently similar In size and shape. Factors which qnhanced flow were short length, wide Internal diameter, tapered hub, and =brand" differences not readily Identifiable. As rapid Intravenous fluid flow ratesmay be life saving In certain patients, it Is recommended that actual flow (lies be considered In the selection of such units. intravenous fluids are probably the mostcommon adjunct of therapy in theEmergency Department. The in1ravenous route is not only the most elflcacious for drug therapy, but the liluidsthemselves may be life-saving, ~articularly for patients in hypov01emic shock. The survival of such ~atients not infrequently depends on fne speed of delivery of IV fluids. "~here are, on the m a r k e t , innumerable IV needles and catheters. Whilethere are many factors that dicute the selection of one unit over In0ther of the same size, the relative IPeed with which fluids can be ielivered through it is not one of ~ern.The factor of flow rate appears 10have completely escaped notice. It0alleviate the oversight, this simple ~tUdywas performed. ~sistant Professor of Emergency ~edicine, Department of Emergency ~edicine, University of Southern Califortia School of Medicine.
Materials and Methods A 500 cc. volume Of tap water, measured with a 500 cc. graduated cylinder, was placed in an empty 1 liter commercial IV bottle. The bottle was suspended on a stand of fixed height, approximately 4 feet above a sink. The fluid was allowed to run into the sink via a standard polyethylene intravenous delivery set through a selection of various types of commonly used IV needles and catheters. The selection included plain needles, scalp vein needles, pediatric feeding tubes, cut-down-type catheters, and a number of the most commonly used IV catheters, both over-needle and through-needle types. The time required to empty the bottle was recorded. Most units were subjected to at least two timed trials. The largest time difference between trials, the variance for identical units, was 10 seconds.
Results ~dress for reprints: Robert H. Dailey, O,Room 1606, Unit l, Los Angeles CounU$C Medical Center, 1200 North State =tteet, Los Angeles, California 90033.
~Jept/Oct 19.73
The units studied are identified by brand, description, catalogue number, and size (Table 1). Timed
flows are tabulated both as absolute units (seconds) and as a'normalized factor of the shortest flow time of 230 seconds. An extremely wide variation in flow times was noted. The factors responsible were these: 1. Internal catheter g a u g e - - f o r the same brand catheters, an increase from 18 to 16 gauge led to a 25-40% increase in flow rate. 2. Shape of catheter h u b - - f o r the same gauge catheters a 20-40% increase in flow rate was found for the tapered hub catheter (Argyle "Medicut") over the conventional non-tapered. 3. Length of device--the longer units provided considerable slower flow rates. Though the Intrafusor (21 inches long) had a very large-bore catheter (15 gauge), it permitted only a very slow flow. For the Deseret Intracath, with units of the same style and bore, a 50% increase in length (8 to 12 inches) slowed flow by 20%. 4. Type of h u b - - w h e r e a conventional "cut-down" hub is inserted into the polyethylene catheter, great slowing occurs due to the relatively small diameter of the hub.
Journal of the American College of Emergency Physicians
Page 341
IV FLOW RATES
5. U n i d e n t i f i a b l e factors a s s o c i a t e d with spec.ific brands--despite almost identical dimensions and appearances, some brands had almost 50% greater flow rates (e.g. contrast B-D and Bardic). Discussion The results largely speak for themselves. It should be emphasized that there are very considerable differences in flow from one unit to another, even when units appear superficially to be quite comparable. Flow rate should not, of course, be the sole determinant in the selection of a unit; safety, cost, ease of insertion, workmanship, and reliability are
additional factors to be considered. This s i m p l e study does not pretend to be exhaustive. It is r e c o m m e n d e d ~ that physicians test the units used in t h e i r e m e r g e n c y d e p a r t m e n t against the results o b t a i n e d here to see h o w they c o m p a r e . As m a x i m a l flow rate has s i g n i f i c a n t p a t i e n t - c a r e i m plications, changes may be in order.
Page 342
Table 1 Flow Rates for 500 cc of Tap Water Through Intravenous Infusion/Unite
Brand
Type
Catheter Gauge (Internal)
Cat No.
Argyle Argyle Deseret Deseret
Medicut 16 1005-16 Medicut 16 1002-16 Angiocath 16 2804 Angiocath 16 2854 Subclavian Deseret Catheter Set 16 755 (Pink Hub) 18 Abbott Scalp Vein 16 B-D Longdwell 16 6758 Sorenson Intrafusor 15 210-014 Argyle Medicut 18 1002-18 Bardic Catheter 18 1963-T Deseret Angiocath 18 2816 Deseret Intracath 16 3362 Deseret Intracath 16 3172 (Yellow Hub) B-D Longdwell 18 6743 B-D Straight Needle 18 Bardic Catheter 18.5 1968T Abbott Scalp Vein 19 B-D Straight Needle 20 Pediatric Feeding Tube #SFR Deseret Angiocath 14 2852 *(Abbott Scalp Vein length includes tubing)
Journal of the American College of Emergency Physicians
Length Inches
4 Time Seconds
(NemalizH' to 230 sic)
51/~ 2 21,~ 51/4
290 230 370 410
1.00 1.61 1.78
12
645
2.81
30* 21/2 21 2 21/~ 2 8 12
270 295 675 347 707 480 500 575
1.17 1.28 2.94 1.51 3.09 2.09 2.17 2.50
21/2 11~ 11,4 6* 11/z
460 490 785 665 1050
2.00 2.13 3.41 2.89 4.56
42 51/4
515 245
2.24 1.07
Sept/Oct 1973 i
F iow rate variance
of commonly used IV units Robert H. Dalley, MD* Los Angeles, California
Twenty commonly used Intravenous needles and catheters were compared ~llh respect to rates of flow of fluid through them. Large differences were en¢0untered even for units apparently similar In size and shape. Factors which qnhanced flow were short length, wide Internal diameter, tapered hub, and =brand" differences not readily Identifiable. As rapid Intravenous fluid flow ratesmay be life saving In certain patients, it Is recommended that actual flow (lies be considered In the selection of such units. intravenous fluids are probably the mostcommon adjunct of therapy in theEmergency Department. The in1ravenous route is not only the most elflcacious for drug therapy, but the liluidsthemselves may be life-saving, ~articularly for patients in hypov01emic shock. The survival of such ~atients not infrequently depends on fne speed of delivery of IV fluids. "~here are, on the m a r k e t , innumerable IV needles and catheters. Whilethere are many factors that dicute the selection of one unit over In0ther of the same size, the relative IPeed with which fluids can be ielivered through it is not one of ~ern.The factor of flow rate appears 10have completely escaped notice. It0alleviate the oversight, this simple ~tUdywas performed. ~sistant Professor of Emergency ~edicine, Department of Emergency ~edicine, University of Southern Califortia School of Medicine.
Materials and Methods A 500 cc. volume Of tap water, measured with a 500 cc. graduated cylinder, was placed in an empty 1 liter commercial IV bottle. The bottle was suspended on a stand of fixed height, approximately 4 feet above a sink. The fluid was allowed to run into the sink via a standard polyethylene intravenous delivery set through a selection of various types of commonly used IV needles and catheters. The selection included plain needles, scalp vein needles, pediatric feeding tubes, cut-down-type catheters, and a number of the most commonly used IV catheters, both over-needle and through-needle types. The time required to empty the bottle was recorded. Most units were subjected to at least two timed trials. The largest time difference between trials, the variance for identical units, was 10 seconds.
Results ~dress for reprints: Robert H. Dailey, O,Room 1606, Unit l, Los Angeles CounU$C Medical Center, 1200 North State =tteet, Los Angeles, California 90033.
~Jept/Oct 19.73
The units studied are identified by brand, description, catalogue number, and size (Table 1). Timed
flows are tabulated both as absolute units (seconds) and as a'normalized factor of the shortest flow time of 230 seconds. An extremely wide variation in flow times was noted. The factors responsible were these: 1. Internal catheter g a u g e - - f o r the same brand catheters, an increase from 18 to 16 gauge led to a 25-40% increase in flow rate. 2. Shape of catheter h u b - - f o r the same gauge catheters a 20-40% increase in flow rate was found for the tapered hub catheter (Argyle "Medicut") over the conventional non-tapered. 3. Length of device--the longer units provided considerable slower flow rates. Though the Intrafusor (21 inches long) had a very large-bore catheter (15 gauge), it permitted only a very slow flow. For the Deseret Intracath, with units of the same style and bore, a 50% increase in length (8 to 12 inches) slowed flow by 20%. 4. Type of h u b - - w h e r e a conventional "cut-down" hub is inserted into the polyethylene catheter, great slowing occurs due to the relatively small diameter of the hub.
Journal of the American College of Emergency Physicians
Page 341
IV FLOW RATES
5. U n i d e n t i f i a b l e factors a s s o c i a t e d with spec.ific brands--despite almost identical dimensions and appearances, some brands had almost 50% greater flow rates (e.g. contrast B-D and Bardic). Discussion The results largely speak for themselves. It should be emphasized that there are very considerable differences in flow from one unit to another, even when units appear superficially to be quite comparable. Flow rate should not, of course, be the sole determinant in the selection of a unit; safety, cost, ease of insertion, workmanship, and reliability are
additional factors to be considered. This s i m p l e study does not pretend to be exhaustive. It is r e c o m m e n d e d ~ that physicians test the units used in t h e i r e m e r g e n c y d e p a r t m e n t against the results o b t a i n e d here to see h o w they c o m p a r e . As m a x i m a l flow rate has s i g n i f i c a n t p a t i e n t - c a r e i m plications, changes may be in order.
Page 342
Table 1 Flow Rates for 500 cc of Tap Water Through Intravenous Infusion/Unite
Brand
Type
Catheter Gauge (Internal)
Cat No.
Argyle Argyle Deseret Deseret
Medicut 16 1005-16 Medicut 16 1002-16 Angiocath 16 2804 Angiocath 16 2854 Subclavian Deseret Catheter Set 16 755 (Pink Hub) 18 Abbott Scalp Vein 16 B-D Longdwell 16 6758 Sorenson Intrafusor 15 210-014 Argyle Medicut 18 1002-18 Bardic Catheter 18 1963-T Deseret Angiocath 18 2816 Deseret Intracath 16 3362 Deseret Intracath 16 3172 (Yellow Hub) B-D Longdwell 18 6743 B-D Straight Needle 18 Bardic Catheter 18.5 1968T Abbott Scalp Vein 19 B-D Straight Needle 20 Pediatric Feeding Tube #SFR Deseret Angiocath 14 2852 *(Abbott Scalp Vein length includes tubing)
Journal of the American College of Emergency Physicians
Length Inches
4 Time Seconds
(NemalizH' to 230 sic)
51/~ 2 21,~ 51/4
290 230 370 410
1.00 1.61 1.78
12
645
2.81
30* 21/2 21 2 21/~ 2 8 12
270 295 675 347 707 480 500 575
1.17 1.28 2.94 1.51 3.09 2.09 2.17 2.50
21/2 11~ 11,4 6* 11/z
460 490 785 665 1050
2.00 2.13 3.41 2.89 4.56
42 51/4
515 245
2.24 1.07
Sept/Oct 1973 i