FROM THE DEPARTMENT OF DIAGNOSTIC RADIOLOGY (DIRECTOR: PROF. U. RUDHE) , HUDDINGE SJUKHUS, S-141 86 HUDDINGE, SWEDEN.
BLOOD INFLOW INTO VASCULAR CATHETERS FOLLOWING INJECTION OF SALINE SOLUTION AND CONTRAST MEDIUM Model experiments MATS DAHLBORN and ULLA SODERLUND Thromboembolism following introduction of catheters into arteries is a wellknown complication of the procedure. Thrombocytes aggregate on the vessel wall or on the outer surface of the catheter and are followed by formation of fibrin sleeves (JACOBSSON & SCHLOSSMAN 1969). When blood enters the catheter lumen the same mechanism also applies for the inner surface of the catheter (SCHLOSSMAN 1973). Intermittent flushing of intravasal catheters with saline solution or with contrast medium is the usual means to avoid this event. According to HAWKINS & HERBERT (1974), contrast medium should be more effective in preventing blood clot formation than saline solution. DAHLBORN et coll. (1978) have shown that the effect of contrast medium is gravity dependent in that the medium leaks out more rapidly from a catheter when the tip is directed downwards than upwards. As the mechanism of blood inflow into catheters following injection of saline solution has not previously been analysed catheters were flushed with saline solution and water soluble contrast media using an experimental model. The results are now reported.
Methods A blood circulation model was used consisting of an electric motor pump connected to plastic tubes filled with blood from human donors (900 ml blood + 130 ml ACD-solution formula A, US pharmacopeia). The pump was generating pulsative Submitted for publication 2 May 1978. Acta Radiologica Diagnosis 20 (1979) Fasc. 3
Downloaded from acr.sagepub.com at CORNELL UNIV on July 18, 2015
439
440
MATS DAHLBORN AND ULLA SODERLUND
Fig. 1. Translucent tube with transparent catheter for blood inflow recording (a), catheter for blood pressure recording (b), and thermometer (c). The tube was connected to a pump (d).
c
movements of the blood imitating the effect of the heart beats. The plunger movements and the volume per beat were adjustable within certain limits. The pulse rate was constant during each experiment and varied between 32 and 44 beats/min. A translucent tube of plastic material (10 10 mm) was connected horizontally to the circulation system (Fig. 1). On the interior surface of the tube a transparent polyethylene catheter (10 1.15 mm) was glued. The free surface of the catheter was painted white to give a suitable background to the blood inflow into the catheter when looking through the translucent tube wall. A catheter for blood pressure recording and a probe for electromagnetic blood flow registration were connected to the tube. The blood pressure varied between 160/0 and 240/30 mmHg, the blood flow between 380 and 700 ml/rnin, Both factors were kept constant during each experiment. To avoid alterations in density and viscosity of the fluids during the experiments a water thermostat kept the temperature of the system on a physiologic level. In all the experiments the blood inflow into the catheters was documented photographically on slides (Fujichrome R 100). In 44 of the total 113 experiments the blood flow into the catheter was recorded after a single fluid injection into the catheter (Table 1). During each experiment 9 films were exposed 0, 15 and 30 s and I, 1.5, 2, 3, 4 and 5 min following the catheter tap closure at the end of the injection. The length of the blood inflow into the catheter was measured on the films. In the remaining 65 experiments continuous fluid injections into the catheter were performed with an automatic syringe pump with adjustable injection speed (Table 2). The following speeds were used: 0.5, 1.2, 2.6 and 4 ml fluid/so During these injections the pulsative blood inflow was recorded photographically by single films and estimated by eye and its maximum and minimum length noted. During the experiments the catheter tip was directed either 50 upwards or 50 downwards, upstream or downstream. The following fluids and densities at 20 to 25°C were used: Isopaque Cerebral (meglumine/calcium-metrizoate, 280 mg l/ml, 1.31 g/ml), Amipaque (metrizamide, 2 - [3- acetamido - 5- N - methylacetamido- 2,4,6-triiodobenzamido]-2-deoxy- D-glucose, 1.057 g/rnl), isotonic (1.004 g/ml) and hypertonic saline (1.055 g/rnl) solutions. The Amipaque and the hypertonic saline solutions were given densities close to the density of ACD blood (1.056). Results In all experiments with a single injection of the flush fluid the lumen of the catheter was completely filled with the fluid at the end of the injection. A few seconds later
Downloaded from acr.sagepub.com at CORNELL UNIV on July 18, 2015
441
BLOOD INFLOW INTO VASCULAR CATHETERS
b
a
Fig. 2. Translucent tube with a catheter glued to its interior surface. Blood inflow into the catheter one min after fluid injection and catheter tap closure. Blood located a) above Isopaque Cerebral, b) below isotonic saline solution. Length of blood column (-+). Catheter tip (+-).
Table 1 Number of experiments following a single fluid injection Total
Tip of catheter directed Upwards Upstream
Downwards Downstream
Upstream
Downstream
Isopaque Cerebral Amipaque Isotonic saline solution Hypertonic saline solution
3 0 3 0
4 4 4 4
3 0 3 0
4 4 4 4
Total
6
16
6
16
44
Table 2 Number of experiments with continuous fluid injection Total
Tip of catheter directed Upwards Upstream Isopaque Cerebral Isotonic saline solution Total
Downwards Downstream
Upstream
Downstream
8 8
8 8
8 8
8 9
16
16
16
17
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65
442
MATS DAHLBORN AND ULLA SODERLUND
Lmm
60
60
40
40
20
20
o
o
o 2
3
4
5
o
2
a
60
60
40
40
20
20
o
o
2
3
3
4
5
b
4
5
o
o
c
2
3
4
5 min
d
Fig. 3. Blood inflow into the catheter after injections of Isopaque Cerebral with a) catheter tip directed upwards, b) downwards, and of isotonic saline solution with c) tip directed upwards, d) downwards. L ~ length of inflow.
the flush fluid in the catheter tip invariably became partially replaced by blood forming a layer below the isotonic and hypertonic saline solutions and the Amipaque and above the Isopaque Cerebral (Fig. 2). The inflow of blood increased continuously during the 5 min of observation. In the experiments with Isopaque Cerebral the length of the blood inflow was less when the catheter tip was directed upwards than when directed downwards (Fig. 3 a, b). The average length of the blood inflow 60 s after the end of injection was 7 mm and 33 mm, respectively. The corresponding figures after 5 min were 12 mm and 66 mm. When isotonic saline solution was used as flush fluid the blood inflow into the catheter tip was less when the catheter tip
Downloaded from acr.sagepub.com at CORNELL UNIV on July 18, 2015
443
BLOOD INFLOW INTO VASCULAR CATHETERS Lmm
60
60
40
40
20
20
o
o
o
2
5
3
L~~~~ o
,
i i i
I
2
4
5
4
5 min
b
a
60
60
40
40
20
20
o
o
o
2
3
3
4
5
---~
~~----
o
..
----2
c
3
d
Fig. 4. Blood inflow into the catheter after injections of Amipaque with a) catheter tip directed upwards, b) downwards, and of hypertonic saline solution with c) tip directed upwards, d) downwards. L ~ length of inflow.
was directed downwards than when directed upwards (Fig. 3 c, d). The average length of the blood inflow 60 s after the injection was 9 mm and 17 mm, respectively, and the corresponding figures after 5 min were 19 mm and 59 mm. No differences were found in the amount and speed of the blood inflow when the catheters were directed downstream or upstream. In the experiments with Amipaque the blood inflow into the catheter was much less than in those with Isopaque Cerebral when the tip was directed downwards (Figs 3 b, 4 b). However, when the tip was directed upwards no difference between the contrast media (Figs 3 a, 4 a) was recorded. When hypertonic saline solution
Downloaded from acr.sagepub.com at CORNELL UNIV on July 18, 2015
444
MATS DAHLBORN AND ULLA S{)DERLUND
Lmm
60
60
40
40
20
20
o
o o
3
2
4
/~.
BLOOD INFLOW INTO VASCULAR CATHETERS FOLLOWING INJECTION OF SALINE SOLUTION AND CONTRAST MEDIUM Model experiments MATS DAHLBORN and ULLA SODERLUND Thromboembolism following introduction of catheters into arteries is a wellknown complication of the procedure. Thrombocytes aggregate on the vessel wall or on the outer surface of the catheter and are followed by formation of fibrin sleeves (JACOBSSON & SCHLOSSMAN 1969). When blood enters the catheter lumen the same mechanism also applies for the inner surface of the catheter (SCHLOSSMAN 1973). Intermittent flushing of intravasal catheters with saline solution or with contrast medium is the usual means to avoid this event. According to HAWKINS & HERBERT (1974), contrast medium should be more effective in preventing blood clot formation than saline solution. DAHLBORN et coll. (1978) have shown that the effect of contrast medium is gravity dependent in that the medium leaks out more rapidly from a catheter when the tip is directed downwards than upwards. As the mechanism of blood inflow into catheters following injection of saline solution has not previously been analysed catheters were flushed with saline solution and water soluble contrast media using an experimental model. The results are now reported.
Methods A blood circulation model was used consisting of an electric motor pump connected to plastic tubes filled with blood from human donors (900 ml blood + 130 ml ACD-solution formula A, US pharmacopeia). The pump was generating pulsative Submitted for publication 2 May 1978. Acta Radiologica Diagnosis 20 (1979) Fasc. 3
Downloaded from acr.sagepub.com at CORNELL UNIV on July 18, 2015
439
440
MATS DAHLBORN AND ULLA SODERLUND
Fig. 1. Translucent tube with transparent catheter for blood inflow recording (a), catheter for blood pressure recording (b), and thermometer (c). The tube was connected to a pump (d).
c
movements of the blood imitating the effect of the heart beats. The plunger movements and the volume per beat were adjustable within certain limits. The pulse rate was constant during each experiment and varied between 32 and 44 beats/min. A translucent tube of plastic material (10 10 mm) was connected horizontally to the circulation system (Fig. 1). On the interior surface of the tube a transparent polyethylene catheter (10 1.15 mm) was glued. The free surface of the catheter was painted white to give a suitable background to the blood inflow into the catheter when looking through the translucent tube wall. A catheter for blood pressure recording and a probe for electromagnetic blood flow registration were connected to the tube. The blood pressure varied between 160/0 and 240/30 mmHg, the blood flow between 380 and 700 ml/rnin, Both factors were kept constant during each experiment. To avoid alterations in density and viscosity of the fluids during the experiments a water thermostat kept the temperature of the system on a physiologic level. In all the experiments the blood inflow into the catheters was documented photographically on slides (Fujichrome R 100). In 44 of the total 113 experiments the blood flow into the catheter was recorded after a single fluid injection into the catheter (Table 1). During each experiment 9 films were exposed 0, 15 and 30 s and I, 1.5, 2, 3, 4 and 5 min following the catheter tap closure at the end of the injection. The length of the blood inflow into the catheter was measured on the films. In the remaining 65 experiments continuous fluid injections into the catheter were performed with an automatic syringe pump with adjustable injection speed (Table 2). The following speeds were used: 0.5, 1.2, 2.6 and 4 ml fluid/so During these injections the pulsative blood inflow was recorded photographically by single films and estimated by eye and its maximum and minimum length noted. During the experiments the catheter tip was directed either 50 upwards or 50 downwards, upstream or downstream. The following fluids and densities at 20 to 25°C were used: Isopaque Cerebral (meglumine/calcium-metrizoate, 280 mg l/ml, 1.31 g/ml), Amipaque (metrizamide, 2 - [3- acetamido - 5- N - methylacetamido- 2,4,6-triiodobenzamido]-2-deoxy- D-glucose, 1.057 g/rnl), isotonic (1.004 g/ml) and hypertonic saline (1.055 g/rnl) solutions. The Amipaque and the hypertonic saline solutions were given densities close to the density of ACD blood (1.056). Results In all experiments with a single injection of the flush fluid the lumen of the catheter was completely filled with the fluid at the end of the injection. A few seconds later
Downloaded from acr.sagepub.com at CORNELL UNIV on July 18, 2015
441
BLOOD INFLOW INTO VASCULAR CATHETERS
b
a
Fig. 2. Translucent tube with a catheter glued to its interior surface. Blood inflow into the catheter one min after fluid injection and catheter tap closure. Blood located a) above Isopaque Cerebral, b) below isotonic saline solution. Length of blood column (-+). Catheter tip (+-).
Table 1 Number of experiments following a single fluid injection Total
Tip of catheter directed Upwards Upstream
Downwards Downstream
Upstream
Downstream
Isopaque Cerebral Amipaque Isotonic saline solution Hypertonic saline solution
3 0 3 0
4 4 4 4
3 0 3 0
4 4 4 4
Total
6
16
6
16
44
Table 2 Number of experiments with continuous fluid injection Total
Tip of catheter directed Upwards Upstream Isopaque Cerebral Isotonic saline solution Total
Downwards Downstream
Upstream
Downstream
8 8
8 8
8 8
8 9
16
16
16
17
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65
442
MATS DAHLBORN AND ULLA SODERLUND
Lmm
60
60
40
40
20
20
o
o
o 2
3
4
5
o
2
a
60
60
40
40
20
20
o
o
2
3
3
4
5
b
4
5
o
o
c
2
3
4
5 min
d
Fig. 3. Blood inflow into the catheter after injections of Isopaque Cerebral with a) catheter tip directed upwards, b) downwards, and of isotonic saline solution with c) tip directed upwards, d) downwards. L ~ length of inflow.
the flush fluid in the catheter tip invariably became partially replaced by blood forming a layer below the isotonic and hypertonic saline solutions and the Amipaque and above the Isopaque Cerebral (Fig. 2). The inflow of blood increased continuously during the 5 min of observation. In the experiments with Isopaque Cerebral the length of the blood inflow was less when the catheter tip was directed upwards than when directed downwards (Fig. 3 a, b). The average length of the blood inflow 60 s after the end of injection was 7 mm and 33 mm, respectively. The corresponding figures after 5 min were 12 mm and 66 mm. When isotonic saline solution was used as flush fluid the blood inflow into the catheter tip was less when the catheter tip
Downloaded from acr.sagepub.com at CORNELL UNIV on July 18, 2015
443
BLOOD INFLOW INTO VASCULAR CATHETERS Lmm
60
60
40
40
20
20
o
o
o
2
5
3
L~~~~ o
,
i i i
I
2
4
5
4
5 min
b
a
60
60
40
40
20
20
o
o
o
2
3
3
4
5
---~
~~----
o
..
----2
c
3
d
Fig. 4. Blood inflow into the catheter after injections of Amipaque with a) catheter tip directed upwards, b) downwards, and of hypertonic saline solution with c) tip directed upwards, d) downwards. L ~ length of inflow.
was directed downwards than when directed upwards (Fig. 3 c, d). The average length of the blood inflow 60 s after the injection was 9 mm and 17 mm, respectively, and the corresponding figures after 5 min were 19 mm and 59 mm. No differences were found in the amount and speed of the blood inflow when the catheters were directed downstream or upstream. In the experiments with Amipaque the blood inflow into the catheter was much less than in those with Isopaque Cerebral when the tip was directed downwards (Figs 3 b, 4 b). However, when the tip was directed upwards no difference between the contrast media (Figs 3 a, 4 a) was recorded. When hypertonic saline solution
Downloaded from acr.sagepub.com at CORNELL UNIV on July 18, 2015
444
MATS DAHLBORN AND ULLA S{)DERLUND
Lmm
60
60
40
40
20
20
o
o o
3
2
4
/~.
