CHBT cheat sheet

Hemodialysis removes solute by diffusion down a concentration gradient across a semipermeable membrane; the dialysate flows countercurrent to blood to maximize the gradient.

Uremic solute clearance depends on blood flow rate, dialysate flow rate, membrane surface area, and membrane permeability (Kuf); increasing any of these generally raises clearance until a plateau.

Ultrafiltration removes plasma water by a transmembrane pressure gradient; the ultrafiltration rate equals Kuf multiplied by TMP, and convective drag carries some solute with the water.

Normal glomerular filtration rate is roughly 90-120 mL/min/1.73 m2; dialysis typically provides only a fraction of native clearance, so residual renal function meaningfully improves outcomes.

The kidneys regulate acid-base balance, erythropoietin production, vitamin D activation, and potassium excretion; loss of these functions explains anemia, renal bone disease, and hyperkalemia in dialysis patients.

Dialysis disequilibrium syndrome arises from overly rapid osmolar shifts during early or aggressive sessions, producing cerebral edema with headache, confusion, and seizures.

Adequacy is commonly quantified by Kt/V, where K is clearance, t is session time, and V is urea distribution volume; higher Kt/V indicates more delivered clearance.

Dry weight is the post-dialysis weight at which the patient is normotensive without excess fluid; it is reassessed over time as nutritional status changes.

Hyperkalemia is the most immediately life-threatening electrolyte abnormality in dialysis patients because cardiac conduction is impaired at elevated serum potassium.

Biofeedback is operant conditioning of a physiological response using real-time feedback of an otherwise imperceptible signal, typically paired with a reinforcing target.

The three-phase training model is: develop awareness of the signal, gain voluntary control with feedback present, then transfer control to everyday settings without the instrument.

Autonomic balance is often framed as sympathetic arousal versus parasympathetic tone; slow paced breathing at about six breaths per minute tends to increase vagally mediated heart rate variability.

Respiratory sinus arrhythmia is the beat-to-beat variation in heart rate across the breathing cycle and is a common index of parasympathetic activity.

Skin conductance rises with eccrine sweat gland activity driven by sympathetic cholinergic fibers, making it a sensitive but nonspecific index of arousal.

Peripheral vasoconstriction from sympathetic activation lowers finger temperature; thermal biofeedback trains vasodilation and warming of the extremities.

Surface electromyography measures muscle electrical activity; lower microvolt readings indicate relaxation of the monitored muscle group.

Generalization of training requires practice in varied settings, because skills learned in a quiet clinic do not automatically transfer to the dialysis chair or home.

Common modalities are surface EMG, thermal, electrodermal (skin conductance), heart rate variability, respiratory, and neurofeedback; choice depends on the target symptom and setting.

EMG sensors use three electrodes: an active, a reference, and a ground; skin preparation and consistent placement reduce artifact and improve session-to-session comparability.

Thermal feedback uses a thermistor taped to a fingertip; readings are typically reported in degrees Fahrenheit or Celsius and respond slowly, so changes lag the physiological event.

Skin conductance is measured by applying a small constant voltage across two electrodes, usually on the palmar surface, and is expressed in microsiemens.

Heart rate variability instruments derive beat-to-beat intervals from ECG or photoplethysmography and report time-domain and frequency-domain indices.

Artifact sources include movement, 50/60 Hz electrical interference, poor electrode contact, and loose leads; recognizing artifact prevents misinterpretation of the signal.

Signal filtering and appropriate gain settings improve the usable signal; excessive gain can saturate the display and obscure trends.

Equipment must be cleaned and electrodes replaced per manufacturer guidance; reusable sensors require disinfection between patients.

Sessions are commonly scheduled during the first or second hour of dialysis, avoiding the intradialytic hypotension window and the post-treatment fatigue period.

The fistula or graft arm is avoided for sensor placement; the opposite arm or a non-access site is used to protect vascular access.

Blood pressure cuffs, pulse oximeters, and biofeedback sensors must not be placed on the access extremity because compression or obstruction can thrombose the access.

Intradialytic hypotension, cramping, and nausea are common events; biofeedback training pauses while these are managed and resumes when the patient is stable.

Short practice blocks of roughly 10-20 minutes fit within a typical session and reduce fatigue and boredom while allowing repeated rehearsal across treatments.

Noise, alarms, and staff activity are ongoing distractors; headphones, guided scripts, and consistent cueing help the patient maintain attention to the signal.

Documentation includes modality, sensor site, baseline and end values, duration, patient response, and any adverse events during the session.

Coordination with the dialysis nurse and nephrologist ensures the plan does not conflict with fluid removal goals, medication timing, or access care.

Baseline assessment covers the target symptom, its frequency and intensity, prior coping strategies, medical history, medications, and sensory or cognitive limitations.

Standardized scales such as a 0-10 symptom rating or a validated anxiety inventory provide repeatable measures to evaluate progress across sessions.

Relaxation training components include diaphragmatic breathing, progressive muscle relaxation, guided imagery, and autogenic phrases; paced breathing is often the entry skill.

Progressive muscle relaxation involves brief contraction followed by release of muscle groups, teaching discrimination between tension and relaxation.

Screening for depression, anxiety, sleep disturbance, and pain is important because these symptoms are common in dialysis populations and affect adherence.

Contraindications and cautions include severe cognitive impairment, active psychosis, and uncontrolled arrhythmia; adaptations such as shorter sessions or caregiver support may be needed.

Home practice between sessions consolidates skill acquisition; brief daily practice with a log supports generalization and gives material for review.

Symptom management goals are set collaboratively with measurable targets, such as reducing pre-session anxiety ratings or shortening time to settle.

Practice within the scope defined by licensure and certification; biofeedback certification bodies set separate standards from clinical licensure.

Informed consent covers the purpose, procedures, risks, alternatives, expected benefits, and the patient's right to withdraw at any time.

Confidentiality is protected under HIPAA and professional codes; physiological data and session notes are protected health information.

Dual relationships and boundary issues arise when the practitioner also has another role with the patient; clarify roles and refer when objectivity is compromised.

Report suspected abuse, neglect, or unsafe dialysis practice through the appropriate organizational and legal channels.

Maintain competence through continuing education, and refer patients whose needs exceed the practitioner's training or scope.

Accurate, timely records support continuity of care and are legal documents; avoid altering records retroactively without proper annotation.

Infection control, including hand hygiene and equipment disinfection, applies to every biofeedback encounter, especially in the dialysis unit.