Prospective study of 51 patients with immediate or early malfunction of long-term hemodialysis catheters

Prospective study of 51 patients with immediate or early malfunction  of long-term  hemodialysis catheters

Ahmed M.T. Ghanem(l), MRCS; Amira R. El Tabbakh(2J, M.Sc; Tarek A.AbdelAzim(3J, MD, FRCS

(I)Department of Vascular Surgery, Nasser Institute for Research  &Treatment, Cairo.

(2) Department of Radiology,  Tanta University,  Tanta.

(3) Department of Vascular Surgery, Ain-Shams University,  Cairo.

Introduction: Long-term dialysis catheters provide an important access for hemodialysis for patients with end-stage renal disease. They are however associated with a significant incidence of early malfunction.  The present study aims at identifYing the various causes of long term dialysis catheter early malfunction as well as the accuracy of the currently used diagnostic modalities for assessment of such causes.

Patients  and methods:  51 patients (24 males 27 females, mean age 64.6 years) with early long term dialysis catheter malfunction were included in the study. All patients were evaluated by duplex ultrasonography  and magnetic resonance venography (MRV) and results ofthe two diagnostic modalities were compared.

Results: Both duplex scan and MRV demonstrated central venous thrombosis in 4 patients (7.8%). Central venous attenuation or stenosis secondary to previous catheter insertion was identified in 13 cases (25.5%)  by MRV  but was only detected  in 3 cases (5.9%)  by duplex ultrasonography (p > 0.001).

Conclusion: Causes of catheter malfunction in the present study included malposition, intra or peri-catheter thrombosis, and central vein attenuation  or stenosis. While duplex scan and MRV were equally  accurate in detection of central venous thrombosis, MRV  was much more sensitive in detection of central vein attenuation or stenosis. We recommend the wider use of MRV for investigating  patients with early malfunction of such dialysis catheters as well as for preoperative evaluation of patients with previous catheter insertion.

Key words:  Dialysis catheters-MR venography- Vascular access.

Introduction:

Hemodialysis requires repeated, secure access to the blood stream whilst ensuring an adequate  rate of blood flow. Central venous dialysis catheters provide a readily available, easily placed, reliable vascular access. They can be used immediately once inserted, connection to the dialysis circuit is straight forward and needle free and catheters provide sufficient blood flow to allow adequate hemodialysis. They are, however, commonly associated with a number of complications including   blockage   and  malfunction   as  a

result of either by intra- or peri-catheter thrombosis, malpositioning and/or migration, central venous stenosis or thrombosis, and catheter-related bacteremia and sepsis.l

The  aim of  this study  is to  identify  the causes of immediate  or early failure  (within

7days)  of long-term  hemodialysis  catheters and the accuracy of the current diagnostic modalities for assessment of such causes.

Patients and  methods:

This study was carried out on 51 patients who  presented  to  the   Vascular  Clinic  of

Nasser  Institute  for Research and  Treatment from June 2011 to June 2012 with immediate or early failure (within 7 days) of long term hemodialysis catheters  (Amecath®, Ameco Medical  Industries, EGYPT).

Following thorough history  taking  and clinical  examination, all patients  underwent duplex  scanning and magnetic resonance venography.  Our  focus   in  the  examination was  the  central   venous   system   where  the catheters have been  inserted.  For purpose  of analysis   the  veins   examined  were   divided to the following segments: Internal  jugular vein, subclavian vein, external  iliac vein, and common femoral  vein on both sides.

Duplex ultrasound studies were performed in the  Radiology Department of  Nasser Institute  by a certified radiologist experienced in the  procedure. The  veins  examined were evaluated by  means  of  5-mHz  and  7-mHz linear  array  scanners  (Aspen  Advanced, Siemens  Erlangen, Germany). Examination was performed  in both longitudinal and transverse planes.  Spectral  waveforms were obtained at each examination level, and color Doppler  interrogation was used throughout.

Magnetic  resonance  venography  (MRV)

was performed using a 3 T MRI machine (Siemens  Magnetom  Trio  Tim  System, Munich, Germany) using a phased-array body and  neck  coil.  Scout  images  were  obtained with  a fast  spoiled  low  angle  shot  (FLASH) gradient-echo sequence, 3D  sequence  in the coronal  orientation to depict  the jugular, subclavian, external  iliac,  and  common femoral  vein segments.

Statistical analysis:  Analysis  was done  by use of SPSS program version 17. Data was reported  as mean  ± the standard  deviation of the mean. Results  were compared using Chi­ square   test  for  comparing  proportions  and

2-tailed  Student  t test for  comparing means. Results   were  considered significant at  a  P value less than 0.05.

The  study  was  approved   by  the  Ethics Review  Board of the hospital, and written informed consent  was  obtained  from  all patients  enrolled  in the study.

Results:

The  age  range  for the study  patients  was

53-80 years with a mean age of 64.59±  6.74. Included   were  24  males  (47.1  %)  and  27 females  (52.9%), Table (1).

The distribution of catheter insertion  sites was as follows: Right subclavian vein  17 (33.4%),  left  subclavian  vein   14  (27.5%), right internal jugular  vein  8 (15. 7%), the  left internal jugular vein 6 (11.8%), right common femoral   vein   4  (7.8%)  and   left  common femoral  vein 2 (4.8%),  Table (2).

All  patients   had  previous  temporary  or long term dialysis  catheters  inserted. The number  of previous  catheters inserted  for the study  group is shown  in Table (3).

Duplex scan on the venous system showed

4 cases (7.8%) of deep venous thrombosis, 3 cases (5.9%)  of attenuation of the deep veins while   in  the  remaining  44  cases   (86.3%) no  abnormality  could   be   detected   in  the deep veins and malfunction was considered secondary to catheter malposition.

On the other hand MRV showed  occlusion ofthe deep veins in 4cases (7.8%), attenuation of  the  deep  veins  in  13  cases  (25.5%)  and patent  deep  veins  in the  remaining 34  cases (66.7%), Table (4).

Statistical analysis  showed that sensitivity

of duplex  scan for detection  of the occlusion of  the  central   venous  system  in  relation  to MRV is 41% and the specificity is 100% while the negative  predictive value is 77% and a positive  predictive value of 100%,  Table (5).

There was no significant age difference between  patients  with  occluded  versus attenuated veins.  All  the  patients  with occluded central venous system were females (4/4, 100%). On the other hand females accounted for 61. 5% of cases of central  vein attenuation,  Table (6).   The   most   affected vein segment by attenuation was the right subclavian vein (35.3%) followed by the  left subclavian vein (29.4%),  Table (7).

Patients were managed by flushing and repositioning of the catheters  in 34 cases (66.7%), and catheter  removal was necessary in the remaining 17 patients  (33.3%).

Table (1): Age & gender distribution  of the study group.

Table (2): Distribution of catheter insertion sites.

Table (3): Number  & percent distribution  of previous catheters.

Table (4): Number  & percent distribution  of duplex and MRV results.

Discussion:

Long term dual lumen catheters provide an alternative vascular access in dialysis patients considered  unsuitable  for  arteriovenous fistula, graft or peritoneal dialysis. However, the use of such catheters is often complicated by inadequate blood flow. 2,3

Several factors can account for such low blood flow. Formation  of an intraluminal  or

periluminal catheter clot is a common cause which can be treated or prevented by local flushing with heparinized saline, daily low­ dose warfarin, local thrombolysis, or J-wire passage  through  the  catheter.  Occasionally the low blood flow is related to the catheter tip malposition  or  lying  against the  atrium or central vein wall. Such cases can be repositioned     under    fluoroscopic    control

Table (5): Comparison between duplex & MRV results.

Table (6): Comparison between demographics for patients with occluded & attenuated central vems.

Table (7): Distribution of lesions in the venous system by MRV.

or even by simply changing the patient's posture or by inversion of the arterial and venous  lumen.4   Stenosis  or  attenuation  of the central veins commonly results from previous temporary  or long term dialysis catheter and is another important cause for malfunction of subsequent catheter placement as demonstrated in the present study.

Menegazzo   and  colleagues   reported  on their preliminary experience concerning the value of magnetic  resonance  imaging  in the assessment of the upper limb veins prior to creation ofhemodialysis fistulas emphasizing

its  importance  in  evaluation  of  the  central veins particularly in patients with previous central   vein   cannulation.   In  this   regards MRV provides  a big advantage  over duplex ultrasonography which is less accurate in evaluation ofthe intrathoracic veins.5,6

The utility of balanced steady-state free precession  MR venography  in the diagnosis of lower extremity  deep venous  thrombosis has shown a sensitivity of 94.7%, specificity of 100%, positive  predictive value of 100%, and  negative  predictive  value of 97.7%  for the diagnosis of deep venous thrombosis. 7