The MR of ptns maintained on HDX is unacceptably elevated. With higher morbidity, relatively lowered quality of life
Technical aspects of nocturnal hemodialysis (NH)
Abbreviation (read twice please):
o Ca+ Cl-: Calcium Chloride
o Ca+: Calcium
o CI: contraindications
o CKD: chronic kidney disease
o Conc: concentration
o CVC: central venous catheter
o CVS: cardiovascular
o DX: dialysis
o Dzr: dialyzer
o Dzt: dialysate
o FHN: the Frequent HDX Network
o HCO3: Bicarbonate
o HDX: hemodialysis
o HH: home hemodialysis
o K+: Potassium
o KTx: kidney transplantation
o LMWH: low-molecular-weight heparin
o MR: mortality rate
o Na+: Sodium
o Na+PO4: Sodium Phosphate
o ND: nocturnal dialysis
o NH nocturnal hemodialysis
o PD: peritoneal dialysis
o PTH: Parathyroid hormone
o QB: blood flow rate
o RCT: randomized controlled trial
o Sms: symptoms
o tPA: tissue-type plasminogen activator.
o UF: ultrafiltration
The MR of ptns maintained on HDX is unacceptably elevated. With higher morbidity, relatively lowered quality of life (considering the higher level of dependence on others and unemployment), with higher costs of care have also been reported. The HDX (HEMO) study reported that a higher DX dosing within the general restriction of a thrice-weekly schedules failed to limit ptn MR. The institution of more intense DX schedule seems to be improving morbidity & possibly MR in this ptns cohort. As compared to the conventional thrice weekly schedule, ptns DX with prolonged duration and/or higher frequency could be correlated to better outcomes.
Considering these findings, NH (e.g., long nightly HH) was suggested as a (possible) more accepted alternate to the conventional DX as it’s superiorly providing DX based on dosing, duration, and frequency. This can be achieved as it’s provided during night sleeping on otherwise unproductive timing. I will discuss the NH, especially the current regimen of this procedure.
DX REGIMEN & PRESCRIPTION
Regimen schedule: NH can be provided either at home or in a DX facility. If it’s provided at home, the frequency of DX varies between 3-7 nights/week. Facility-based NH is provided 3 nights a week.
Personnel: Facility-related DX is usually performed by an attending staff. Home DX is performed through the ptn himself or via a helper (paid/unpaid). An attended partner is NOT absolutely mandated for nocturnal DX at home, as this procedure is usually associated with a significantly hemodynamic stable ptn.
HDX machines: NH can be accomplished with any HDX machine. Attractive facilities of a HH machine may include:
o Easy operation/disinfection,
o Single-needle facility,
o Lowered noising production,
o Remote monitoring facility of the ptn.
o Easily accessed screen diming at night,
o Back-up batteries to guard against power failure, &
HH machines can provide high or low Dzt flow. The available machines that approved for HH in the US are: Fresenius 2008K, NxStage One & One S, & Tablo.
Dzr membrane: Any Dzr membrane can be provided, including smaller surface area Dzr. Although there’re no published reports favoring one type of Dzr over others, most centers are providing high-flux Dzrs.
Time: NH is preferably with sleeping for a different amount of time (usually 6 to >10 hs), according to the targeted length of sleep. For facility-based DX, the duration of the DX session is usually given by the facility logistics.
Dzt composition: is variable according to the type of DX machine (high/low flow).
High Dzt flow (conventional) machines: Typically composed of:
o Na+: 138 mEq (mmol)/L.
o K+: 2 mEq (mmol)/L.
o HCO3: 30 mEq (mmol)/L for nightly schedule & 35 mEq (mmol)/L for every other night or thrice-weekly schedules.
o Ca+: 2.5-4 mEq/L (1.25 -2 mmol/L), averaging of 3.2 mEq/L (1.6 mmol/L). Dzt Ca+ is adjusted to preserve PTH in a desired range while keeping normal pre-DX Ca+. Dzt Ca+ can be adjusted by changing the amount of Ca+ Cl- powder added to the Dzt (e.g., 7 mL of Ca+ Cl- powder added to 4 L of acid Dzt concentrate can increase the Ca+ by 0.5 mEq/L [0.25 mmol/L]).
o An increased Dzt Ca+ may be provided in ptns with high UF volumes to guard against the negative Ca+ balance. As removing Ca+ (ionized) with HDX is generally proportional with the volume of the UF volume. Moreover, pregnancy or hungry bone syndrome also requiring higher levels of Dzt Ca+.
o PO4: 0-4.5 mg/dL (0-1.5 mmol/L), ideally 1.2 mg/dL (0.4 mmol/L). Na+PO4 (as Fleet enema) is usually added, if required, into the acid or HCO3 concentrate. Dzt PO4 is adjusted to keep pre- & post-DX PO4 within normal range. Typical dosing is 30-60 mL per Dzt concentrate jug, but higher dosing of 200 mL can be provided as a source of PO4 for ptns with increased requirements, those ptns who’re pregnant or with hungry bone syndrome. Ca+ & PO4 do not precip-itate in the acidic pH. Intermittent NH is less likely to need PO4 additives.
Low Dzt flow machine: Dzt composition of the low Dzt flow machine (i.e., NxStage) is usually fixed that it cannot be altered during DX session.
o Na+: 140 mEq (mmol)/L
o K+: 1-2 mEq (mmol)/L
o Lactate: 40 or 45 mEq (mmol)/L
o Ca+: 3 mEq (1.5 mmol)/L
According to the given Dzt volume, a higher lactate conc of 45 mEq/L is used with low Dzt flow machine may elevate serum HCO3 excessively.
No Dzt additives are possible with using the NxStage machine.
Blood and Dzt flow rates: With conventional DX machines, a blood flow as low as or < 200 mL/min is adequate for most ptns undergoing NH. However, a blood flow of 200-300 mL/min may be typically provided. QB with low Dzt flow machines (i.e., NxStage) is higher (>300 mL/min) to keep the widest blood/Dzt solute gradient.
Dzt flow rate is variable, depending on the type of DX machine. For a high Dzt flow machine, Dzt flow is ranging from 100-800 mL/min. The Dzt flow in a lower Dzt flow machine can’t be < 63 mL/min. So, the entire Dzt volume is required to be monitored to accommodate the target duration of therapy.
UF: The typical daily UF volume removal is about 1-2 L, however, higher volumes can be tolerated. Ptns must weigh themselves daily to keep their dry weight, defined as: normotension with no need for antihypertensive agents or edema.
Dzr reuse: Reprocessed delayed Dzr has been utilized. Certain DX machines may be used in situ Dzr reprocessing. Many centers mostly providing new Dzrs.
Anticoagulation: To provide systemic anticoagulation, the standard heparin regimen can be administered as 1000 units heparin/h. Danaparoid & argatroban can also be provided successfully with heparin allergy. A single dose of LMWH at the start of DX has been successfully applied.
Access: Both CVC & peripheral vascular access have been successfully applied in NH. If peripheral access is used, however, several access cannulations may induce lowered access survival. This was suggested by the FHN Daily & Nocturnal trials, where the primary vascular outcome was the timing to 1st access event (repaired access, lost access, or access with hospitalization), and the secondary vascular outcome was the timing to all repairs and timing to all losses.
In the FHN Nocturnal trial, 87 ptns were receiving in-center, 6 d./week HDX or conventional, 3 d./week HDX. As compared to conventional DX, there was a non-significant attitude toward an increasing rate of 1st access event with ND. If ptns with tunneled catheters were excluded, ND was complicated with a significantly higher risk of a 1st access event. In the FHN Daily trial (n = 245 ptns), there was a higher trend of the 1st access events in the daily group as compared to the conventional group.
Catheters: Any type of CVC can be utilized for NH. The ability of the catheter to provide blood flow >200 mL/min is not important for most ptns. A safe connection for the CVC includes using pre-perforated catheter caps that’re not removed during DX. Careful taping of the catheter-tubing is crucial. Accidentally disconnected venous limb may induce exsanguination without triggered machine alarms.
o Thrombosis: Locally instilled 2 mg of alteplase (tPA) has been successfully restored an accepted blood flow in the blocked catheters. With instilled lyophilized tPA, it can be practiced successfully by ptns at home. The approach to manage the catheter thrombosis is varying in different centers. Prophylactic tPA has been suggested to guard against catheter thrombosis.
o Infection: DX catheter-related infection can be seen with ptns on HH using a temporary or tunneled DX catheter. Study: 98 ptns on NH utilizing catheters, 64 % were complicated by bacteremia along 7 ys; the most common isolated pathogen was S. epidermidis (51 %).
The frequency of these infections with HH can be compared to that in ptns on in-center HDX, e.g., one study compared the rate of 1st catheter infection among these groups, ptns on HH had somewhat fewer episodes of infection (1.77 vs 2.03 /100 ptn-mo,), despite the difference between groups was insignificant.
Arteriovenous (A/V) fistulas: An A/V fistula is the preferable access. The standard steel needle, blunt needle, & plastic cannulas have been utilized safely. The buttonhole pattern involving the inserted needle/cannula through exactly the same hole and at the same angle and depth of penetration, can be applied by most ptns. After 8-10 cannulations (or 12-14 in diabetics) with the buttonhole method, an epithelialized track will be developed allowing using of the blunt needle. Sharp needle should be utilized in the 1st week, followed by "blunt" ones thereafter. Before cannulating, the fistula and surrounding skin are disinfected with chlorhexidine gluconate (0.5% in 70% alcohol) or povidone-iodine disinfection. Scabs can be covered with an alcohol pad for 5 min., then removed with a sterile needle. Mupirocin Ca+ 2% cream (Bactroban) can be applied to each buttonhole using a sterile cotton swab after reaching hemostasis and permitted for air dry.
A single set is given for each HDX session. Using Mupirocin for prophylaxis seems to significantly limit the risk of S. aureus bacteremia with buttonhole technique. The Buttonhole technique without using local Mupirocin can be complicated with S. aureus bacteremia, usually with life-threatening metastatic sepsis. Risk of sepsis was assessed in the following reports:
●A RCT comparing 140 conventional HDX ptns assigned to either the buttonhole technique or "rope-ladder" bricking. After 8 weeks, the rate of localized sepsis was higher among ptns on the buttonhole technique in comparison with conventional bricking (50 vs 22.4/1000, resp). One episode of S. aureus bacteremia at 8 weeks and 2 more episodes within 12 mo after the study was terminated in the group utilizing the buttonhole maneuver vs none in the conventional one. At 12 mo, the number of bricking site abscesses on need to IV AB was higher in the buttonhole group vs the conventional one (9 vs zero, resp.). The degree at which this information from conventional HDX ptns could be extrapolated to nocturnal daily HDX or self-cannulating ptns is not certain.
●A retrosp. review comparing the buttonhole maneuver with rope-ladder cannulation among 90 HH ptns. Over 3765 A/V fistula-months, there were 17 systemic infectious episodes related to fistula infections. As compared with rope-ladder, the buttonhole maneuver was complicated with an increased rate of total fistula (non-systemic) infection. Lost fistula or requiring surgical intervention was similar between the groups, despite intervention by the radiologist was not included in the analysis. An accompanied systematic reviewing also reported higher risk of infection with the buttonhole maneuver as compared with other maneuvers in 4 RCT, as well as in observational reports.
So, considering the higher risk of infection, avoiding the buttonhole maneuver has been recommended by some clinicians. However, S. aureus bacteremia has been rarely seen with the introduction of mupirocin. Most centers do not practice the buttonhole maneuver for facility-based DX.
The buttonhole maneuver may be complicated with fewer thrombotic sequalae among ptns on nocturnal/daily DX. In the FHN report, compared with the rope-ladder maneuver, the buttonhole maneuver was correlated with prolonged intervals between access-related event(s) that could be correlated mostly by the reduced thrombotic events. The buttonhole maneuver may be also improving fistulae survivals among ptns on conventional HDX. Regardless the technique (i.e., buttonhole vs rope ladder), more frequent cannulation may induce to more frequent access-related sequalae.
A/V grafts: have been successful. The buttonhole maneuver is not applied with this access. A different hole is utilized with every DX. A steel needle or plastic cannula can be used. Superiority should be directed to the single-needle technique to limit the number of cannulations. The single-needle maneuver can provide accepted blood flow (average 200 mL/min), it provides more safety with accidental disconnection by triggering the air-detecting alarm. So, it could be the access maneuver of choice for NH.
SAFETY: Safety while on HH is of outmost importance. HH is generally considered to be safer, provided that ptns are strictly selected, well-trained, and observing the given safety maneuvers. One report: 2 adult HH programs (Canada), there was only one death and 6 potentially fatal events among 190 ptns and about 500 ptn-ys of treatment; 6 of the 7 events include bleeding, and 5 of 7 involved a human error with lapsed established protocol.
To assure the safety of this procedure, tight needle taping with anchored blood tubing is crucial; enuresis pad wrapped around the connection is also important. 2 moisture sensors are placed on the floor to recognize any Dzt or blood leaking. Blood leak can trigger the audible alarm. Dedicated disposable leak sensors are available, as well as non-disposable wireless leak sensors that stop the blood pump when triggered.
More recent technologic updates have been admitted, e.g., a tight clamp connected to the blood-loss sensor with clamping the venous line on sensing any moistening with forcing the DX machine to be held and alarming.
As noted above, a single-needle maneuver is providing an extra safety with accidental disconnection via triggering an air detector alarm. Certain centers may be practicing the live remote monitoring of ptns at home. All the data present on the DX machine, including the triggered alarms, are also obviated to an observer at the following center. Ptn who was not awakened by the current alarm will be called. Live monitoring may provide the following benefits:
o Data collection
o Ptn reassurance
o Ensured compliance
o Preventing blood clotting within an idle extracorporeal system
Despite the aforementioned benefits, this monitoring may not be detecting the life-threatening states. So, its application is optional. Most centers do NOT apply the remote monitoring of ptns on NH, despite some centers may use remote monitoring for certain ptns or for short periods (3 mo.s).
PATIENT SELECTION & TRAINING: All ptns with ability of practicing HH or ptns with home helper are candidates for NH. Exclusion criteria may include
1) Acute illness,
2) Resistant seizure activity,
3) Labile type 1 DM (with no helper), &
4) CI to systemic anticoagulation.
The finding of older age, unstable CVS system, hypotension, DM, and/or ascites are ALL indications, and NOT CI, for NH. A given aid to encourage home DX choice for ptns has been provided. Ptns cohorts that can be preferably targeted for NH may include:
o Ptns following in a CKD clinic. Preventing the dependence setting commonly seen in in-center DX units, training them should be commenced early or ptns may be dialyzed temporarily as self-care therapy. Utilized transitional care unit setting is growing leading to an increasing number of ptns choosing HH.
o Ptns ineligible for KTx. NH can be offered as a DX modality nearest to KTx.
o Ptns with significant morbidity, e.g., cardiac disease, DM, severe HT, DX-related Sms, or higher interdialytic weight gain.
o Ptns requiring shifting from PD to HDX or wanting to keep independence.
o Large-sized ptns or ptns with inadequate DX due to inadequate access flow.
The adopted NH could be precluded by ptn-related barriers, including lacked confidence in his own ability to perform the desired duties (e.g., self-cannulating), fearing of devastating events, and the reluctance in regard to burden family members/caregivers. Financial burden could be of concern. Costing may include higher home utility fees and lowered DX reimbursement schedule, particularly if > thrice-weekly DX will be provided.