Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5224_Библиотеки_им_академика_М_И_Перельмана.pdf
42 Overview, Technical Aspects, and Safety of RRT Modalities in Critical Care 507
include CVC dislodgement, accidental extubation, bleeding, and patient falls with or
without bodily injury. A meta-analysis demonstrated a low occurrence of adverse
events in CRRT patients, prompting further research to explore strategies to enhance
the feasibility and safety of physiotherapy in this vulnerable population [
43].
The Process of RRT Prescription and Administration
The CRRT administration process involves a series of interconnected and
interdependent phases.
The first phase is the diagnosis of AKI and the identification of indications for the
initiation of CRRT treatment.
Once the CRRT treatment is indicated, the physician proceeds with the prescription of the treatment by filling in the prescription, indicating clearly and unambiguously the following:
1. The type of treatment
2. The vascular access to use
3. The type of filter
4. Blood flow, effluent dose and its repartition into convective and diffusive doses,
the predilution percentage, weight loss (net ultrafiltration), and correction of the
effluent dose for the dilution factor due to the predilution
5. The composition of hemodiafiltration fluids
6. The type of anticoagulation and the dose of the anticoagulant
7. Clarifications on the treatment with relative recommendations in relation to the
clinical conditions of the patient
Once the prescription has been issued , the nurse has to understand the prescription, prepare the materials matching with the prescribed treatment, proceed with the
priming of the monitor for CRRT, and enter the treatment parameters for the correct
and safe execution of the treatment.
Once the monitor has been primed and the self-tests have been passed, the nurse
should prepare the CVC for the connection to the extracorporeal circulation.
When the monitor is connected to the CVC, it is possible to start CRRT treatment,
checking that the extracorporeal circulation and CVC are well functioning.
During the treatment, the nurse has to carry out periodic checks on the set
parameters and verify the blood flow, the integrity of the filter, the absence of filter
and ex tracorporeal circulation clotting, the patient’s hemodynamics, and the adequacy of the net ultrafiltration compared to the patient’s fluid balance.
alfuncti
Any m
the continuation of the treatment and its safety.
The effi
periodic checks of the ions and renal indices. At the end of the scheduled treatment,
the nurse proceeds to discontinue the treatment.
on or alarm has to be promptly analyzed and solved to guarantee
cacy and efficiency of the treatment have to be monitored through the
508 F. Nalesso et al.
Any complication of treatment delivery should be reported immediately by the
nurse to the treating physicians.
Each phase of the treatment is connected to the next. Treatment management
requires specific skills and sufficient experience to solve the most comm on technical
and clinical problems that may occur.
Indications of RRT
The KDIGO Guidelines recommend urgent dialysis start in life-threatening conditions [11]. These are:
• Hyperkalemia refractory to medical treatment (e.g., K > 6.0 mmol/l or rapidly
increasing with ECG alterations)
• Uremic complications such as pericarditis, bleeding, encephalopathy
• Progressive fluid accumulation and/or complication of fluid overload (e.g., pul-
monary edema)
• Poisoning with dialyzable toxins (e.g., toxic alcohol, salicylates, lithium)
• Persistent or worsening acidosis that is refractory to medical management (e.g.,
pH < 7.20)
These conditions require urgent treatment, and KRT cannot be delayed.
In the case of hyperkalemia, when therapeutic measures aimed at facilitating the
intracellular shift of potassium (such as the correction of acidosis with bicarbonate,
glucose, and insulin infusion and beta-2 agonist administration) fail, the excess
potassium, especially in oligo-anuric patients, can only be eliminated with RRT.
Metabolic acidosis is a frequent clinical problem that affects patients with severe
AKI. However, metabolic acidosis associated with AKI can usually be corrected
with bicarbonate and usually does not require RRT unless it is accompanied by
severe volume overload or uremia. Metabolic acidosis can be caused by a variety of
poisons, drug overdoses, and toxic compound exposure (such as salicylates, ethylene
glycol, methanol, metformin), some of which can also lead to AKI. In these
circumstances, RRT may also facilitate the removal of the offending drug and
improve acid-base disorders. Certain molecules that can be easily removed by
dialysis are lithium, methanol, and salicylates.
Uremic pericarditis, pleuritis, encephalopathy, and coagulopathy (usually caused
by uremic platelet dysfunction) are traditional indications of RRT. These conditions
are complications of AKI or ESRD and can be corrected only with RRT [
Fluid overload
patients with AKI to favor fluid management. When fluid overload cannot be
managed by pharmacologic treatment—usually by increasing loop diuretics dose
or combining diuretics or by sequential nephron blockade—and there is persistent or
worsening oliguria, RRT is required to achieve fluid balance. Studies confirmed that
patients with positive balance fluid in the ICU have a higher mortality rate than
patients with normal fluid balance. So patients with initial or mild kidney
is one of the major symptoms of AKI; diuretics are often used for
11].
42 Overview, Technical Aspects, and Safety of RRT Modalities in Critical Care 509
dysfunction with persistent positive water balance may take advantage, in terms of
mortality rate, of an early start of RRT. It is important to underline that diuretics must
be used to manage fluid overload as needed but not to treat AKI.
However, recommendations consider the broader clinical
context, the presence of
conditions that can be modified with RRT, and trends of laboratory tests—rather
than single blood urea nitrogen (BUN) and creatinine thresholds alone—when
making the decision to start RRT [11].
Recently, there have been expanded indications of dialysis, also called “nonrenal
indications,” although in this setting, there is low agreement. Extracorporeal therapies in sepsis are useful in immunomodulation or in restoring immune homeostasis.
The removal of sepsis mediators with hemoperfusion is associated with lower
mortality if compared with conventional therapy. Another indication is the removal
of cytokines in sepsis, which can be combined with polymyxin B hemoperfusion
(sequential extracorporeal therapies), although this approach is currently controversial [44]. Volume removal and the prevention of excessive fluid accumulation in
heart congestive failure, for example, can be useful for controlling fluid balance also
in patients without AKI [45].
Refractory respiratory acidosis in ARDS and severe acute exacerbation of chronic
obstructive pulmonary disease (ae-COPD) could benefit from extracorporeal carbon
dioxide removal (ECCO
ventilation, managing CO
then reducing acute pulmonary injury caused by ventilators [
R). This technique allows applying ultraprotective lung
2
levels by reducing current volumes to <6 ml/kg, and
2
46].
Timing
The optimal timing of dialysis for AKI is not clearly defined. Timing may be
considered the time between reaching RRT start criteria and RRT effective start.
The current literature based on randomized controlled trials has not been able to
clarify the ideal time for starting RRT in AKI. In these trials, no difference in
mortality rate was proved between patients with early-start dialysis and those with
late start. However, physicians may not postpone treatment until the appearance of
pulmonary edema or serious hyperkalemia [
11].
In conclusion, in current practice, the decision to start RRT is based most often on
the clinical features of volume overload and the biochemical features of solute
imbalance (azotemia, hyperkalemia, severe acidosis) [11].
Prescription Parameters
The prescription of RRT treatments provides for a series of common param eters that
contribute to obtaining an effective and safe treatment for the patient (Table 42.2).
The aspects
that have to be considered in the prescription phase are:
510 F. Nalesso et al.
4 times per week plus additional
treatments as indicated
Kt/V (thrice weekly) 1.3, Kt/V
(weekly) 3.9
150–180
.7 1.7–2
treatments as indicated
CVVH CVVHD CVVHDF SCUF SLED IHD
Table 42.2 Prescription of RRT treatments
24 24 24 Variable 6 to 18 3 to 6
Treatment duration
(h/day)
Frequency Daily Daily Daily Variable 3 times per week plus additional
Ultrafiltration Diffusion/convection/both Diffusion/convection/both
convection
Convection Diffusion Diffusion +
Mechanism of solute
removal
0 1500–2000 1000–1500 0 100–300 ml/min 300–800 ml/min
150–250 150–250 150–250 100–200 100–300 200–300
Dialysate flow (ml/h)
Blood flow (ml/min)
(Qb)
(Qd)
1500–2000 0 1000–1500 0 Variable 0
Ultrafiltrate flow (ml/h) 1500–2000 Variable 1000–1500 100–300 Variable Variable
Replacement fluid for
zero balance (ml/h)
Effluent volume (l/d) 36–48 36–48 36–72 2 to 8 Variable Variable
20–25 ml/kg/
h
20–25 ml/
kg/h
kg/h
Optimal dose (ml/kg/h) 20–25 ml/
Urea clearance (ml/min) 25–33 25–33 25–33 1 to 5 90–140
Filter size (m^2) 0.6–1.5 0.6–1.5 0.6–1.5 0.4–1
42 Overview, Technical Aspects, and Safety of RRT Modalities in Critical Care 511
• Blood flow, Qb (ml/min)
• The type of filter in terms of the membrane, the surface, and other characteristics
• The type of monitor for CRRT
• Dialysate flow, Qd (ml/min or ml/h)
• Total reinfusion, Qr (ml/min or ml/h)
• The percentage of predilution of total reinfusion (%)
• Net ultrafiltration (weight loss) in ml/h or L/h
• Maximal ultrafiltration to achieve weight loss (ml/h)
• The dose of heparin or LMWH (UI/h), the initial bolus of anticoagulants in UI,
the prestop of anticoagulation (minutes)
• The composition of dialysate and reinfusion fluid for IRRT/the composition of
hemodiafiltration fluids for CRRT
• The temperature of dialysate/patient thermal balance in CRRT
• The citrate dose for CRRT in RCA (mmol/L)
• Calcium compensation in CRRT in RCA (mmol/L or % of compensation)
• The duration of treatments (hours/day)
• The frequency of treatments (treatments/week)
A major determinant of an effective Qb (blood flow) is well-functioning vascular
access. Adequate blood flow allows for stable extracorporeal circulation with adequate flows for convective and diffusive processes. According to the filtration
fraction, the prescription of a standard CVVH usually requires Qb less than
200 ml/min, while the prescription of CVVHD usually needs blood flow around
100–150 ml/min. These flows change, for example, in the case of coupling CRRT
with ECCO
R[35].
2
The use of diffusion and convection depends on the spectrum of target molecules
to be removed. The total dose to be administered and the distribution between
convective and diffusive doses depend both on the patient’s weight and the characteristics of the molecules. The use of predilution results in a reduction of the total
purifying dose administered, which requires dose adjustment.
The choice of dialysate and reinfusion composition fluid depends on the patient’ s
ionemia, acid-base balance, and other infusions administered to the patient.
The patient’s thermal balance should be taken into account at the time of
prescription, considering the patient’s hemodynamic status, the presence of hypothermia or hyperpyrexia, or special clinical needs.
leedin
The b
g risk and the contraindications to citrate use have to be analyzed
when prescribing anticoagulation.
While the duration of CRRTs is 24 h per day with an effluent dose calculated
according to guidelines, there is no uniform approach to the prescription of SLED
(hybrid treatment in general), and it varies at different centers with respect to the
duration and frequency of treatments, blood flow rate, dialysate flow rate, filter size,
and patient’s clinical characteristics [9]. Typically, these treatments last between
6 and 12 h per day and are delivered daily or 3 to 6 days per week. Normally, the Qd
is between 100–200 ml/min and Qb 150–400 ml/min [
7]
(Table 42.2).
512 F. Nalesso et al.
Like SLEDD, the prescription of IRRT is affected by various factors and local
policies, being modified over time depending on the patient’s KT/V.
The life span of a circuit depends on many factors: inadequate anticoagulation,
high filtration fraction (FF, defined as the ratio of net plasma water removal rate to
the plasma flow rate delivered to the filter), and the malfunctioning of vascular
access. By prescribing a CRRT treatment, clinicians have to be aware that the FF
should not exceed 20–25% to reduce the risk of circuit clotting. When prescribing a
treatment, physicians should bear in mind that postdilution is more efficient than
predilution in terms of solute clearance, but it can raise filtration fraction, leading to
shorter life span of the circuit [3].
All these factors must be taken into consideration when prescribing treatment to
ensure efficiency and safety for the patient.
Dosing
In terms of intensity, randomized clinical trials did not prove the superiority of
intensive vs less-intensive prescription of RRT [9].
The KDIGO Guidelines suggest prescribing CRRT effluent flows of 20–25 ml/
kg/h. Considering the downtime, a prescription in the range of 25–30 ml/kg/h is
generally required to reach the target.
As far as the prescription of SLED is concerned, no statistical difference in terms
of survival and renal recovery was seen when comparing a standard dialysis dose
and an intensi fied dialysis dose.
For what concerns IHD treatment adequacy, there is no evidence supporting that
higher Kt/V confers any benefits in terms of mortality or renal recovery; thus, the
recommended Kt/V is 1.3 or weekly Kt/V of 3.9 in AKI. As recommended in
KDIGO Guidelines, the frequent assessment of the actual delivered dose to adjust
the prescription is warranted [11].
Membrane Choice
In terms of membrane choice, hemofilters in CRRT use synthetic membranes such as
AN69, polyarylethersulfone (PAES), polyethersulfone (PES), and polysulfone (PS).
All these membranes are highly biocompatible without evidence of superior outcomes with any particular material [47]. In the KDIGO Guidelines, awareness is
raised about the risk of bradykinin release syndrome, which has been reported in
patients receiving ACE-i and IHD with an AN69 membrane [11].
Depending on the clinical conditions of the patient, specific blood purification for
target molecules can be required using either medium or high cut-off filters or filters
that can adsorb specific molecules on the membrane.
42 Overview, Technical Aspects, and Safety of RRT Modalities in Critical Care 513
Dialysate and Reinfusion Solutions
In regard to fluid composition in RRT, clinicians can tailor the prescription based on
patients’ electrolyte and acid-base status: a variety of fluids for hemodiafiltration are
available on the market with different concentrations of sodium, calcium, potassium,
magnesium, phosphate, lactate, and bicarbonate.
An important issue that affects up to 65% of RRT patients is hypophosphatemia,
which is associated with respiratory muscle weakness, and myocardial dysfunction,
arrhythmias, leukocyte dysfunction, rhabdomyolysis, and increased mortality. This
electrolyte disorder can be prevented and/or corrected by the employment of a
replacement solution with a higher phosphate concentration. Some—though
weak—evidence suggests that patients receiving phosphate-containing CRRT solutions have shorter hospital stays and longer ventilator-free days
[48]. Hypophosphatemia and hypopotassemia are compliances with prolonged
CRRT and require hemodiafiltration fluid personalization [49].
Hypomagnesemia and hypocalcemia are some frequent electrolyte disorders in
patients undergoing CRRT/SLED treatments in RCA requiring an adaptation of the
prescription and type of hemodiafiltration fluids [35].
KDIGO Guidelines suggest using bicarbonate, rather than lactate, as a buffer in
dialysate and in replacement fluids for RRT in patients with AKI, especially in those
with circulatory shock and liver failure, where lactate metabolism might be impaired.
Bicarbonate was shown to be more effective in correcting acidosis and improving
hemodynamic tolerance [11].
Clinicians prescribing CRRT in RCA treatment should also be aware that the
citrate load can determine variation in bicarbonatemia [35].
Limitations of RRT in Critical Care
Clinicians should be aware that RRT is an invasive procedure and the decision to
start RRT and so both complications as well as ethical aspects should be taken into
account.
First, RRT requires a catheter placement, which can be a dangerous procedure in
patients with coagulation disorders, a higher risk of bleeding, or hematoma formation. CVC placement increases also the risk of CVC-related infection. Femoral
central venous catheters are more prone to infection.
Moreover, RRT increases the risk of hemodynamic instability, and this is usually
due to the net ultrafiltration rate. This risk is lower in CRRT than in intermittent
methods.
The use
tions. The use of systemic heparin can precipitate heparin-induced thrombocytopenia. Other complications are hemolysis in the circuit and platelet aggregation
deficiency [4].
of anticoagulation increases the risk of bleeding and bleeding complica-
514 F. Nalesso et al.
There may be electrolyte disturbances caused by electrolyte removal during
dialysis, resulting in hypophosphatemia and hypokalemia, and RCA itself can lead
to other electrolytic derangements.
CRRT can also be responsible for a considerable loss of nutrients crossing the
dialysis membrane. Drug clearan ce during RRT varies markedly depending on drug
type, protein binding, volume of distribution, and renal clearance of the drug. Drug
pharmacokinetics in septic shock, together with RRT, make drug metabolism
complex [50].
No statistically significant difference in mortality, length of stay, and dialysis
dependence between CRRT, IHD, and SLED has been revealed in recent metaanalyses and systematic reviews.
The ethical aspects to be considered are the patient’s life expectancy and safety,
the therapeutic objective, and the ethical principle of nonmaleficence.
Other aspects to be taken into account are increased ICU nurse support; increased
risk of immobilization of the patient, preventing rehabilitation; and increased
overall cost.
Patient Safety During RRT in Critical Care
Introduction
In recent decades, the term “patient safety” has gradually become more prominent in
the medical literature due to an increased awareness that unintended and often
avoidable harm can result from health care interventions. A great deal of evidence
has been yielded documenting the extent of preventable harm in hospital care, and
attention is turning to seeking new strategies to improve patient safety by changing
the systems in which care is provided, recognizing and limiting “human factors.”
anage
The m
requires a multidisciplinary approach to diagnostic and treatment procedures, such
as RRT. The complexity of these patients and the new technologies available to
perform RRT require clinical risk analysis and the introduction of protocols, procedures, and operating instructions to reduce clinical risk through the promotion of a
culture of safety for all providers.
In critical
due to their complexity and the need for a multidisciplinary approach. This complexity can increase medical errors with potential clinical incidents for patients.
Therefore, RRT becomes a high-risk procedure when it is not performed in a skilled
environment where staff experience can result in a significant reduction in the risk of
incidents.
ment of a patient with AKI, especially in the critical care setting,
nephrology, extracorporeal blood treatments are a source of clinical risk
42 Overview, Technical Aspects, and Safety of RRT Modalities in Critical Care 515
Identification of Frequent Errors
The clinical process from the identification of the correct renal function replacement
treatment to its prescription, administration, and management is complex and consists of many interconnected steps where an error in one can have repercussions in
the next. Therefore, in this process, the care provider who materially makes the error
is not always the one who generates it. It is then necessary to trace all the steps in the
process and all care providers involved in the RRT administration. In detail, as an
error can occur at any step and propagate throughout the process, every step
interconnection needs to be identified and described. This approach helps find
effective tools to prevent error recurrence.
In providing RRT treatment, these are the different types of errors that can occur:
• Errors in the parameters of the treatment prescription: these errors involve the use
of incorrect nomenclature, in the prescription, and the incorrect choice of mate-
rials/devices (e.g., those that do not match with the treatment type prescribed).
• Errors in the setting of the prescribed treatment: these errors concern the setting of
blood flow, dialysate flow, reinfusion flows, the units of measurement of flows,
the percentage of pre- and postdilution reinfusion, and filtration fraction; inap-
propriate weight loss; the settings of anticoagulation with citrate or heparin and
low-molecular-weight heparin doses; and the composition and choice of
hemodiafiltration fluids.
• Errors in determining the discrepancy between the prescribed and the adminis-
tered doses, depending on the patient’s weight, the dilution factor, and treatment
downtime.
• Errors in the choice of materials: these concern the incorrect association between
the blood purification technique and the characteristic of the filter, according to its
intended use, and between the acid-base and electrolyte patients’ needs and the
composition of the hemodiafiltration fluids. These errors lead to incorrect treat-
ment prescription and delivery with possible iatrogenic damage to the patient,
such as electrolyte alteration.
Steps in RRT Management and Protocol Application
In the critical care setting, the administration of RRT is a process with an inherent
degree of “unsafety.” As RRT may be administered in an environment outside the
nephrology-dialysis setting by trained but unqualified personnel, patients may be
exposed to increased clinical risk, which can lead to errors and incidents. All these
elements have to be taken into consideration to build a safe environment based on the
introduction of protocols, procedures, operating instructions, and checklists aimed at
mitigating clinical risks.
To minimize errors in the parameters of treatment prescription, it is recommended
that the treatment be monitored by specialized and skilled staff who are responsible
516 F. Nalesso et al.
for verifying the consistency of the treatment with the prescription. It is suggested
that this procedure be checked according to a protocol and a codified checklist for
each treatment available. It is recommended that the most critical parameters (weight
loss, fluid balance, anticoagulation, blood flow, status of the extracorporeal circuit,
central venous catheter, treatment parameters, and type of hemodiafiltration fluids)
should be checked every 6 h using a checklis
t that obliges operators to check each
element. This process has to be shared among the different caregivers in the
multidisciplinary team by proper communication. As a matter of fact, communication among care providers is fundamental for RRT management. Unstructured and
uncodified communication between physicians (nephrologists and intensivists) and
nurses can be the error source for the presence of incorrect or missing parameters that
might be misinterpreted by
nurses during treatment delivery. Therefore, to ensure the
highest safety level, the communication process has to be codified through the use of
standardized forms, protocols, procedures, and checklists that are specifically
designed for the center’s needs. This process can help better identify active and/or
latent failures and propose corrective measures for organizational processes.
The encoded comm
unication and safety tools have to be widely known by all
caregivers to ensure proper safety culture. In the RRT administration, the most
critical point for communication is the handover, which has to be structured to
improve safety by coding shared information so that the sender and receiver can
both understand whether the process has been carried out correctly. Therefore, it is
useful to implement communication through the so-called “closed-loop communication” so that all providers are able to verify the exact and complete communication
process of the patient’s clinical condition through a clear and shared language in
terms of parameters and RRT nomenclature, which can be understood by all providers involved in the patient’s care. The understanding of the RRT prescription by
nurses is fundamental for preparing the RRT monitor with the correct materials and
settings at the software level. Any error in reading or understanding the RRT
prescription or the use of wrong materials or incorrect settings generates errors
that can cause harm to the patient in the next steps (priming phase, RRT administration, ...). The use of checklists and operating instructions can reduce clinical risks
by introducing tools that stop treatment progre ssion in the presence of errors or
inconsistencies with the RRT prescription. The extensive introduction of protocols
and operating instructions, with detailed materials and indications about how to
perform each step of the treatment, results in a standardization of the process that can
be checked by all caregivers. Team training plays a key role in increasing patient
safety. In fact, it is necessary to provide ongoing theoretical and practical skills for
the staff to make communication effective and to acquire patient management
abilities to prevent and identify potential risks. All caregivers have to be aware
that they are a part of a system that ensures safety by taking a proactive and reactive
role in clinical risk management through the incident reporting process. Briefings
should be supported to promote a “no-fault culture,” so that everyone is encouraged
to report an incident knowing that the focus is on “how and why” an incident
happened rather than on “who” made the mistake. It is well known that the reactive
approach, based only on measures adopted after an incident is identified, exposes