Buttonhole versus Stepladder Cannulation for Home Hemodialysis

A Multicenter, Randomized, Pilot Trial

Abstract

Visual Abstract

Background and objectives 

Canadian home hemodialysis guidelines highlight the potential differences in complications associated with arteriovenous fistula (AVF) cannulation technique as a research priority. Our primary objective was to determine the feasibility of randomizing patients with ESKD training for home hemodialysis to buttonhole versus stepladder cannulation of the AVF. Secondary objectives included training time, pain with needling, complications, and cost by cannulation technique.

Design, setting, participants, & measurements 

All patients training for home hemodialysis at seven Canadian hospitals were assessed for eligibility, and demographic information and access type was collected on everyone. Patients who consented to participate were randomized to buttonhole or stepladder cannulation technique. Time to train for home hemodialysis, pain scores on cannulation, and complications over 12 months was recorded. For eligible but not randomized patients, reasons for not participating in the trial were documented.

Results 

Patient recruitment was November 2013 to November 2015. During this time, 158 patients began training for home hemodialysis, and 108 were ineligible for the trial. Diabetes mellitus as a cause of ESKD (31% versus 12%) and central venous catheter use (74% versus 6%) were more common in ineligible patients. Of the 50 eligible patients, 14 patients from four out of seven sites consented to participate in the study (28%). The most common reason for declining to participate was a strong preference for a particular cannulation technique (33%). Patients randomized to buttonhole versus stepladder cannulation required a shorter time to complete home hemodialysis training. We did not observe a reduction in cannulation pain or complications with the buttonhole method. Data linkages for a formal cost analysis were not conducted.

Conclusions 

We were unable to demonstrate the feasibility of conducting a randomized, controlled trial of buttonhole versus stepladder cannulation in Canada with a sufficient number of patients on home hemodialysis to be able to draw meaningful conclusions.

Introduction

Patients treated for ESKD with conventional thrice-weekly in-center hemodialysis have limited life expectancy and poorer quality of life than the general population (¹). Frequent and/or longer hemodialysis sessions at home have been associated with regression of left ventricular hypertrophy, improved longevity, and better quality of life (^2–5); however, frequent hemodialysis appears to be associated with a higher risk of arteriovenous fistula (AVF) complications (⁶,⁷).

Cannulation of an AVF is by one of two different methods, stepladder or buttonhole (⁸,⁹). The needle insertion sites are changed for each hemodialysis treatment in the former, but kept constant in the latter, resulting in the formation of a fibrous tract. The presence of a fibrous track may simplify needle insertion for patients and reduce home hemodialysis training time (⁹,¹⁰). Other reported benefits of buttonhole cannulation include fewer needle infiltrations (⁸,⁹,¹¹), fewer interventions (¹²), and a reduction in aneurysm formation (¹³). The effect of buttonhole use on needling pain is controversial with some studies suggesting less (^13–15), no difference (¹⁶), or even more pain (¹²). There is, however, a growing concern that the buttonhole technique may be associated with a higher risk of infection, with estimates for Staphylococcus aureus bacteremia ranging from 0.15 to 0.60 episodes per 1000 patient-days (^17–20). The consequences of S. aureus bacteremia secondary to buttonholes have included septic arthritis, endocarditis, septic pulmonary emboli, vertebral osteomyelitis, and death (¹⁹,²¹). In one small study, the risk of infection associated with buttonhole cannulation was lower with the application of topical mupirocin at the buttonhole sites after hemodialysis (¹⁹).

The relative benefits and risks of buttonhole versus stepladder cannulation have not been explored in a randomized, controlled trial of patients on home hemodialysis. The need for further research in this area was highlighted in the recently published Canadian guidelines on intensive hemodialysis (²²). The primary objective of our multicenter pilot study was to determine the feasibility of randomizing 70% of eligible participants on home hemodialysis to buttonhole versus stepladder cannulation technique for the definitive study. Secondary objectives were to determine the training time, pain scores with needling, AVF complications (infection rate [local and systemic], hematoma formation, missed needle sticks, aneurysm formation, and radiologic/surgical interventions), and cost associated with each of the needling techniques.

Materials and Methods

All eligible patients training for home hemodialysis at seven academic centers in Canada (Ottawa Hospital, London Health Sciences Centre, Foothills Hospital [Calgary], Humber River Regional Hospital [Toronto], Vancouver General Hospital, University Health Network [Toronto], and St. Michael’s Hospital Toronto]) were invited to participate in the study. We obtained research ethics board approval at each of the centers (Board of Record: Ottawa Health Science Network Research Ethics Board, approval no. 20130148-01H) and the trial adhered to the Declaration of Helsinki. The trial was registered with Clinicaltrials.gov (number NCT01962025) on October 14, 2013.

Inclusion and Exclusion Criteria

We included all adult patients who were >18 years old, training for home hemodialysis with an AVF requiring self-cannulation, able to give informed consent, and had life expectancy >12 months. The exclusion criteria were patients who had the potential to be lost from the program within 12 months of training (planned living donor transplant, transfer to peritoneal dialysis, or move from training center catchment area), had short segments or aneurysms within the AVF that the attending nephrologist/nurse educator believed required buttonhole cannulation, had mechanical heart valves, and required intradermal lidocaine for needle insertion.

Randomization and Intervention

Patients enrolled in the study were randomized to either stepladder or buttonhole cannulation technique via a computer-generated model using randomly selected block sizes, with stratification by site and AVF type (incident versus prevalent), by a statistician with no access to participant assignment. Group assignment was kept in a sealed opaque envelope and provided to each participating center to be opened at time of consent by the research coordinator. Each site was provided with data collection forms to collect variables of interest.

Patients were trained according to usual home hemodialysis unit policies with the exception of the needle insertion protocol, in which a topical antiseptic to clean the AVF before needle insertion and the use of a topical antimicrobial cream to buttonhole sites after dialysis was mandated. The time required to teach proficiency in home hemodialysis was documented, including the number of days required for the patient to competently place their own needles without the assistance of the dialysis nurse. If a patient had to return to the home hemodialysis unit to develop a new buttonhole site, the training time was documented and added to the total training time for that patient. Only the investigators and the research coordinators at each site were made aware of the training time as an objective of the study as the intervention could not be blinded and the outcome could potentially be influenced by factors other than needle insertion technique. Patients were followed for a total of 12 months after training was completed.

Baseline Data Collection

After providing informed consent, the following baseline demographic data were collected: age, sex, race, cause of ESKD, ESKD vintage, types of access, access interventions (such as angioplasties, surgical revisions), history of access infection, and comorbidity information to calculate the Charlson comorbidity index (²³).

Demographic data were also retrospectively collected on patients who were training for home hemodialysis but were not eligible or declined to participate in the randomized study. For eligible but not randomized patients, reasons for refusal to participate in the trial and cannulation technique being used at completion of home hemodialysis training was collected from the patient chart.

Primary and Secondary Outcomes

Our primary objective was to determine the feasibility of randomizing eligible participants on home hemodialysis to buttonhole versus stepladder cannulation technique. The key secondary objective was total training time defined as the number of days from start of training to discharge to home. The time required to teach proficiency in self-cannulation was also documented. Other secondary objectives included pain, complications, and cost. Patients were asked to rate their pain on AVF cannulation with a visual analog scale (VAS) measured in millimeters (from 0 to 100), within the first 2–3 days of initiation of home hemodialysis training, at the end of the training period and at approximately 2 months after graduating to home hemodialysis; a higher score indicates greater pain intensity. Topical anesthetics were not withheld during assessment of pain with the VAS but the requirement for use was noted. Patients were instructed to monitor for any signs of localized infections over the AVF (heat, erythema, purulent drainage, or induration), document on the standardized worksheet, and notify their home dialysis unit team. In the event of any infectious symptoms, patients were advised to come to the hospital where the AVF could be assessed and blood cultures drawn as appropriate. Patients were also asked to document any hematoma formation (obvious bruising at the AVF site that occurred at the time of needle insertion or withdrawal) or missed needle sticks (unable to use the needle for dialysis) on the standardized worksheet that was completed after each dialysis. For the buttonhole cannulation group, the need to utilize a sharp needle as opposed to a blunt one was considered a missed needle stick even if a separate needle insertion site was not required. Incidence of these complications and contact dermatitis were determined from patient interview and review of the patient’s standardized worksheet. The presence of aneurysms was documented by the vascular access coordinator at the start, 6 months, and at completion of the study, supported by pictures taken of each patient’s AVF at those same time points. The participant’s electronic medical records were reviewed every 2 months for any AVF radiologic or surgical interventions. The potential resource implications of the different needling strategies on health system costs was to be determined retrospectively upon completion of the definitive trial and included infection-related emergency room visits, hospitalizations, diagnostic imaging and surgical procedures related to the AVF needling technique, and training time.

Stopping Rules

The study would be stopped by the Data Safety Monitoring Board if infection rates were comparable or greater to the benchmark for central venous catheters as adopted by Ottawa Hospital, or if recruitment targets were significantly less than required for the definitive trial (²⁴). The Data Safety Monitoring Board consisted of a senior statistician, nephrologist, and a vascular access coordinator, and met quarterly.

Power Considerations and Statistical Analyses

Given the limited number of patients who start home hemodialysis in the participating centers each year across Canada (N≈70), we estimated that we required at least 70% of eligible patients to enroll in the pilot study to have a large enough sample size in the definitive trial to detect a difference in training days. The mean number of training days for patients with an AVF in the Frequent Hemodialysis Network studies was 27.7 days (±10.4), which was reduced by 5 days for patients using a central venous catheter (¹⁰). Assuming that buttonhole cannulation would have a similar effect on training time, 69 patients per group would give us 80% power to detect this difference.

Basic demographic characteristics of the eligible (consented or declined) and excluded patients are described using appropriate descriptive statistics. Outcomes were to be analyzed on an intent-to-treat basis upon completion of the definitive study, provided that the trial was feasible (vanguard style). Here, we descriptively present the results of the feasibility trial as we lacked a sufficient number of participants to perform a formal analysis.

Results

Primary Outcome (Feasibility)

Patients were recruited from November 2013 to November 2015, during which time 158 patients started training for home hemodialysis, of which 50 patients were eligible for the study and 14 consented to participate (28% of eligible).

The overall population training for home hemodialysis were mostly white (65%), and the average age was 56±16 years (Table 1). The most common vascular access was a central venous catheter (53%), followed by AVF (41%) and arteriovenous graft (6%). Of the108 patients ineligible to participate, the most common reason for exclusion was central venous catheter use (n=80) (Figure 1).

Table 1. - Patients training for home hemodialysis

Characteristics	All	Eligible	Not Eligible
	n=158	n=50	n=108
Men	87 (55)	33 (66)	54 (50)
Age, yr	56±15	55±13	56±16
Comorbidity score a	5.0±5.1	4.9±2.9	5.0±2.6
Race
White	103 (65)	30 (60)	73 (68)
Black	20 (13)	8 (16)	12 (11)
Asian	17 (11)	7 (14)	10 (9)
Other	15 (9)	5 (10)	13 (12)
Cause of kidney disease
Diabetes mellitus	39 (25)	6 (12)	33 (31)
Polycystic kidney disease	17 (11)	9 (18)	8 (7)
GN	44 (28)	20 (40)	24 (22)
Other b	58 (37)	153 (30)	43 (40)
ESKD vintage, yr, median (IQR)	2.4 (1.2–6.0)	1.7 (1.0–4.3)	2.8 (1.3–6.8)
Access
CVC	83 (53)	3 (6) c	80 (74)
AVF	65 (41)	46 (92)	19 (16)
AVG	10 (6)	1 (2)	9 (8)
Previous access
Had 1 CVC	61 (39)	15 (30)	46 (43)
Had >1 CVC	49 (31)	17 (34)	32 (30)
No CVC	47 (30)	21 (42)	26 (24)
Had 1 AVG/AVF	47 (30)	23 (46)	24 (22)
Had >1 AVG/AVF	15 (9)	6 (12)	9 (8)
No AVG/AVF	96 (61)	24 (48)	72 (67)

Data are presented as n (%) or mean±SD, unless otherwise indicated. IQR, interquartile range; CVC, central venous catheter; AVF, arteriovenous fistula; AVG, arteriovenous graft.

^aCharlson comorbidity index score.

^bIncludes congenital, hypertension, multiple myeloma, hemolytic uremic syndrome, obstruction, nonresolved AKI, lithium, cardiorenal, renal cell carcinoma, and unknown.

^cPatients had developed AVF and were thus deemed eligible.

Figure 1.: Patients training for home hemodialysis and final inclusion in the randomized controlled trial. AVG, arteriovenous graft; CVC, central venous catheter; RCT, randomized controlled trial.

Of the 50 eligible patients, 36 did not consent to participate (Figure 1). The mean age of those who declined was 56±13 years and 64% were men. They had ESKD for a shorter median duration than those who were randomized (1.7 [interquartile range, 0.9–3.4] versus 3.1 [interquartile range, 1.1–14.3] years) (Table 2). Reasons for refusal to participate in the study included a stated preference for buttonhole cannulation (n=12) or declining participation without further documentation (n=11) (Table 3). However, nine of the 11 patients without documentation went home using buttonhole cannulation.

Table 2. - Eligible patients by randomization status

Characteristics	Randomized n=14	Not Randomized n=36
Men	10 (71)	23 (64)
Age, yr	53±13	56±13
Comorbidity score a	4.8±3.4	4.9±2.7
Race
White	11 (79)	19 (53)
Black	0	8 (22)
Asian	2 (14)	5 (36)
Other	1 (7)	4 (11)
Cause of kidney disease
Diabetes mellitus	3 (21)	3 (8)
Polycystic kidney disease	0	9 (25)
GN	6 (43)	14 (39)
Other	5 (35)	10 (28)
ESKD vintage, yr, median (IQR)	3.1 (1.1–14.3)	1.7 (0.9–3.4)
Access
CVC	0	3 (8) b
AVF	14 (100)	32 (89)
AVG	0	1 (3)
Previous access
Had 1 CVC	3 (21)	11 (31)
Had >1 CVC	7 (50)	9 (25)
No CVC	4 (29)	16 (44)
Had 1 AVG/AVF	3 (21)	18 (50)
Had >1 AVG/AVF	0	5 (14)
No AVG/AVF	11 (79)	13 (36)

Data are presented as n (%) or mean±SD, unless otherwise indicated. IQR, interquartile range; CVC, central venous catheter; AVF, arteriovenous fistula; AVG, arteriovenous graft.

^aCharlson comorbidity index score.

^bPatients had developed AVF and were thus deemed eligible.

Table 3. - Patient enrollment per site

Home hemodialysis patients by site	Site 1	Site 2	Site 3	Site 4	Site 5	Site 6	Site 7
Patients training for home HD	16	26	9	26	36	11	34
Eligible randomized	2	2	0	3	1	0	6
Eligible not randomized total	2	7	5	3	11	4	4
Pt wants buttonhole	1	2	1			4	4
Pt wants stepladder	1
Research related		3	2
Declined		1	2		8
Difficult needle				1
Care staff decision				2	2
Pt no longer pursuing home HD					1
In RCT endograft study		1

Pt, patient; HD, hemodialysis; RCT, randomized controlled trial.

Of the 14 patients that consented to the study, eight were randomized to buttonhole and six to stepladder cannulation (Table 4). The two groups were similar, with the exception of sex and cause of kidney disease. The trial was stopped early as the definitive trial was not going to be feasible.

Table 4. - Patient characteristics for randomized patients

Characteristics	Buttonhole, n=8	Stepladder, n=6
Men	7 (88)	3 (50)
Age, yr	50±14	51±16
Comorbidity score	3.6±2.3	3.0±1.5
Race
White	6 (75)	5 (83)
Black	0	0
Asian	1 (13)	1 (17)
Other	1 (13)	0
Cause of kidney disease
Diabetes mellitus	2 (25)	1 (17)
GN a	1 (13)	5 (83)
Other b	5 (63)	0 (0)
ESKD vintage, yr (median, IQR)	2.2 (0.2–14.0)	2.5 (0.6–13.4)
Access c
CVC	0	0
AVF	8 (100)	6 (100)
AVG	0	0
Previous access d
Had 1 CVC	2 (25)	1 (17)
Had >1 CVC	4 (50)	3 (50)
No CVC	1 (13)	2 (33)
Had 1 AVG/AVF	2 (25)	0
Had >1 AVG/AVF	0	1 (17)
No AVG/AVF	5 (63)	5 (83)

Data are presented as n (%) or mean±SD, unless otherwise indicated. IQR, interquartile range; CVC, central venous catheter; AVF, arteriovenous fistula; AVG, arteriovenous graft.

^aIncluded secondary FSGS.

^bCongenital, renal cell carcinoma (²), hypertension, unknown.

^cOne patient with a buttonhole cannula was missing data.

^dTwo patients with buttonhole cannulas were missing data.

Secondary Outcomes

Total training time for patients with buttonholes was 19±5 days with 0.3±1 days retraining compared with 29±14 days and no retraining days for patients using stepladder cannulation (Table 4). The VAS pain scores at 2 months post-training were higher in the buttonhole group (Figure 2, Table 5). During the 12-month participation phase, no local or systemic infections were documented. Complications noted in the buttonhole group included reports of contact dermatitis (n=3), stenosis requiring angioplasty (n=4), aneurysm (n=3), and hematoma (n=1). Complications reported in the stepladder group included contact dermatitis (n=1), stenosis requiring angioplasty (n=3), and hematoma (n=5). Neither group required surgical revisions. No hospitalizations related to access were reported in either arm. There was tremendous variability in the number of missed needle sticks documented in each 2-month block. Two patients in the buttonhole group did not document on their standardized data collection tool; documentation was sporadic for other patients. With these caveats in mind, the buttonhole group missed a median of 25.0 (interquartile range, 10.8–49.8) needles, and the stepladder group missed a median of 5.5 (interquartile range, 1.8–60.3) needles.

Figure 2.: Pain with buttonhole cannulation was not less than with stepladder cannulation. Data are presented as mean±SD.

Table 5. - Secondary outcomes

Secondary outcomes	Buttonhole	Stepladder
Total training time, d, mean±SD	19±5	29±14
Pain, mm, a median (IQR)	7.9 (0–30.3)	8.9 (2.7–19.1)
Complications/adverse events, N (%)
Contact dermatitis	3 (38)	1 (29)
Aneurysm	3 (38)	0
Hematoma	1 (13)	5 (83)
Interventions
Surgical, N (%)	0	0
Radiologic (angioplasty for stenosis) (N)	4 (50)	3 (50)
Missed needles median (IQR)	25.0 (10.8–49.8)	25±32 5.5 (1.8–60.3)

IQR, interquartile range.

^aMeasured at follow-up (2 months); a higher score indicates greater pain.

No formal costing information was collected as the data linkages were not established for the feasibility trial period.

Exploratory Outcomes

The average time to independent needle proficiency was 13±5 days in the buttonhole group and 24±12 days in the stepladder group. The VAS pain scores at 2–3 days after starting training were not different between the two groups but were higher in the buttonhole group on the final day of training (Figure 2).

Discussion

Despite our best efforts to conduct the first randomized, pilot trial that would have ultimately allowed us to determine the relative benefit and risks of buttonhole versus stepladder cannulation for patients on home hemodialysis, were unable to consent enough participants to demonstrate feasibility of the definitive randomized, controlled trial. There are several other examples in nephrology in which investigators were unable to recruit the number of participants required to be able to draw statistically valid conclusions (²⁵,²⁶).

In our study, there are at least two separate issues that contributed to our difficulty in recruiting patients. The first challenge is the increasing central venous catheter use in Canadian patients on hemodialysis (²⁷). Patient preferences have been shown to be important in central venous catheter use, but there also appears to be a change in the demographic of the current home hemodialysis cohort in Canada (²⁸,²⁹). In the previously reported Canadian Slow Long Nightly Extended Dialysis Programs (CAN-SLEEP) cohort, only 30% of the patients used a central venous catheter compared with almost 50% of the current cohort (²⁹). There are several factors that have been associated with central venous catheter use in conventional hemodialysis, including older age, black race, female sex, diabetes mellitus, peripheral vascular disease, late referral to nephrology, and cardiac disease (³⁰). Our cohort appears to be a bit older, with more women and greater percentage of participants with diabetes mellitus as the cause of their ESKD compared with the CAN-SLEEP cohort.

The second issue appears to be a strong patient and/or provider preference for buttonhole as opposed to stepladder cannulation. In our study, 12 out of the 36 patients (33%) who were eligible but not randomized during the study stated a preference for the buttonhole cannulation technique as their primary reason for declining participation. We did not explore the reasons for patient’s stated preference for buttonhole cannulation or their sources of information. In a previous study, patients who were exposed to both stepladder and buttonhole cannulation favored the latter technique (¹⁵). We also did not verify that patients were truly making informed choices about the potential risks versus benefits of the two cannulation techniques. Low health literacy has been associated with hemodialysis access choice, but may not apply to patients on home hemodialysis or cannulation technique (³¹). Alternatively, there may also be health care provider preference for training patients to do buttonhole instead of stepladder cannulation (¹⁵). Facility preferences have previously been reported to be a major determinant of the type of vascular access most commonly used in the program (³²). This is consistent with our cohort, with only four of the seven sites randomizing patients for our feasibility trial. In the Dialysis Outcome and Practice Patterns Study, clinical units in which the medical director (typically nephrologists) or nurse manager expressed a preference for arteriovenous graft were more than twice as likely to have an arteriovenous graft than an AVF (³³). It is unclear if these in-center hemodialysis observations apply to the home dialysis unit, but it is plausible. Exploring patient, physician, and nursing views on buttonhole and stepladder cannulation requires further investigation using qualitative methods to understand the issues that are influencing the decision-making process. A recent systemic review examining the use of advanced medical technologies at home identified a lack of literature exploring the views of nurses on this topic, including user experiences of nurses with different technologies, training, instruction, and education (³⁴).

Our participant numbers and low event rates prevent us from drawing any conclusions about the risks and/or benefits of one cannulation technique over another. However, as originally hypothesized, training time does appear to be shorter with buttonhole cannulation. This could be a very important factor influencing health care provider preference for buttonhole cannulation. We did not show a reduction in cannulation pain with the buttonhole method consistent with other studies (⁹,¹⁶). We also did not show that buttonhole cannulation was associated with less missed needle sticks. This was in part related to our definition in which having to use a sharp needle was considered a missed needle stick. We felt this was appropriate for two reasons. For a patient at home, having to resort to preparing a second needle for AVF cannulation adds to the hemodialysis preparation time. There is also the potential for damage to the fibrous tract with unsuccessful needle cannulation that might increase the risk for subsequent infection. These last two points, less pain and perceived ease of cannulation, may be very important in patient-stated preference for buttonhole cannulation.

To address issues of feasibility, future studies of cannulation techniques in home hemodialysis should look to include additional sites, potentially outside of Canada where central venous catheter use is lower (²⁷). Perhaps a greater effort to educate patients with appropriately developed tools, similar to decision aids, may increase recruitment rates. “Pretraining” patients to needle their AVF using the stepladder technique while they are still dialyzing in-center may alleviate patient concerns about their ability to learn this skill and make them more amendable to randomization at a later date. A cluster-randomized trial design could also be considered in an attempt to address the patient and provider equipoise. The ongoing challenges with randomized, controlled trials in nephrology need to be solved, as the use of observational data to drive decision-making has let to incorrect conclusions in the past (³⁵,³⁶).

In summary, we were unable to demonstrate feasibility of completing a randomized controlled trial of buttonhole versus stepladder cannulation for patients planning to start home hemodialysis. Part of the challenge appears to be related to a changing home hemodialysis patient demographic. However, patient and provider values and preferences appear to have also hindered our ability to recruit patients. This latter area needs to be explored further as appropriate decision-making requires a complete understanding of the risks and benefits inherent in any treatment.

Disclosures

None.