25th July 2023

Nutrition and Physiology

Malnutrition

Overview

Malnutrition is a multi-system disorder and one of the most common nutritional challenges among the UK geriatric population. Common symptoms include low energy, unintentional weight loss, and perioral and nail lesions. Consider a biopsychosocial approach for the causes of malnutrition. These include conditions such as Alzheimer’s Disease, dysphagia, poor oral health, severe learning disabilities or mental health problems, frailty, immobility, and catabolic states. Social factors include poor diet, isolation and the inability to do their own food shopping. Complications include frequent falls, chest infections secondary to muscle weakness, low mood and anxiety, heart failure, worsening underlying chronic conditions and immunosuppression. This can lead to loss of independence, prolonged hospital stays, and in severe cases, death.

Assessment

• BMI is a key measure (weight in kg divided by height in metres squared) and classifies malnutrition as mild (17-18.5), moderate (16-17) and severe (<16)
• The Malnutrition Universal Screening Tool (MUST)
• The Mini Nutritional Assessment Short Form (MNA®-SF)

Consider offering nutritional support to the following:

• BMI <18.5
• Unintentional weight loss of more than 10% in the past 3-6 months
• Little or no food intake for >5 days and who are unlikely for the next >=5 days
• BMI <20 and unintentional weight loss of more than 5% in the past 3-6 months
• Poor absorption/high nutrient losses/increased nutritional needs

Micronutrient Deficiencies

Table 1: Micronutrient deficiencies – causes, manifestations, and management

Acute Management

Patients at high risk of malnutrition must be identified early to prevent and monitor for refeeding syndrome. High risk patients include those who are frail, have existing comorbidities, low physiological reserve, chronic malnutrition, chronic alcoholism, postoperative and have long term use of antacids and antibiotics.

Refeeding syndrome is a potentially fatal condition that develops due to the shift of electrolytes and fluids in a malnourished patient post commencement of enteral or parenteral nutrition. Biochemically it can present as electrolyte deficiencies, namely hypophosphatemia, hypomagnesemia, and hypokalemia. Fluid balance abnormalities, abnormal glucose metabolism and thiamine deficiency, can also occur. Hence, patients should be assessed for dehydration, hypoglycaemia, anaemia, and infection alongside malnutrition.

To prevent refeeding syndrome:

• Check and correct electrolyte levels prior to commencement of nutrition, with subsequent daily checks for a week and at least three times the following week.
• Electrolyte supplementation, either orally, enterally or intravenously, should be given unless levels are high prior to commencement of nutrition.
• Refeeding started at no more than 50% of normal energy requirements in high-risk patients, i.e. in those who have eaten little or nothing for more than five days, with the aim to increase the rate if tolerated.
• For high-risk patients, nutritional energy repletion started slowly with a maximum of 10kcal/kg/24hrs, and the rate increased to meet full needs over 4-7 days.
• For Patients who are severely malnourished, i.e., BMI of 14 or less, or have had a negligible intake for two weeks or more, refeeding should start at a maximum of 5kcal/kg/24hrs with cardiac monitoring.

Pressure Ulcers

Overview

A pressure ulcer is an area of erythema that can progress to the breakdown of the skin and underlying structures, such as the bone and muscle, to form an erosion or ulcer. It is due to persistent pressure, heat, friction, or a combination of both to the affected area. Prolonged periods of pressure reduce blood flow to the skin and underlying structures. It can develop in any area of the body, but mainly overlying bony prominences such as the sacrum. Risk factors include chronic conditions, immobility, moisture (incontinence), poor wound healing (malnutrition), urinary tract infections and stroke.

Assessment

Risk assessment tools such as Norton, Braden and the Waterlow scales can be used to identify patients at risk of developing pressure sores. When ulcers are assessed, it is important to check for local signs of infection. The classification system from the European Pressure Ulcer Advisory Panel Grading System is outlined below. 

Table 2: European Pressure Ulcer Advisory Panel Grading System

Management

Pressure ulcers are difficult to heal, painful and can negatively impact the patient’s quality of life. Management includes good nutrition, appropriate wound management, adequate pressure distribution (suitable mattresses and repositioning) and analgesia. Key management points include:

• Moist wound environment encourages ulcer healing. Hydrocolloid dressings and hydrogels can help facilitate this. Discourage the use of soap as it can cause drying of the wound.
• Wound swabs are not routinely done as most pressure ulcers are colonised by commensal bacteria (polymicrobial).
• Decision to treat with systemic antibiotics is based on clinical judgement, i.e., spreading cellulitis, underlying osteomyelitis, clinical evidence of sepsis
• Consider referral to Tissue Viability Nurse (TVN).
• Surgical debridement may be beneficial for selected wounds.
• Do not routinely offer nutritional supplements to patients with adequate nutritional status to prevent pressure ulcers.

Continence

Overview

Continence is the ability to control one’s bladder and bowel. This topic will mainly focus on urinary incontinence in the elderly. Urinary incontinence is defined as the involuntary leakage of urine and can be classified as below.

• Functional incontinence: inability to reach the toilet in time due to poor mobility and/or unfamiliar surroundings.
• Stress incontinence: secondary to exertion or effort/sneezing/coughing/laughing. The bladder sphincter is incompetent and can be associated with genitourinary prolapse.
• Urge incontinence: associated with or immediately preceded by the urge to urinate. Urgency can be defined as the sudden and strong desire to urinate that cannot be deferred. It is because of detrusor instability or hyperreflexia, which leads to involuntary detrusor contraction. This may be idiopathic or secondary to neurological conditions such as multiple sclerosis, Alzheimer’s dementia, spinal cord injury and Parkinson’s disease. It can also be caused by infection or bladder stones which cause local irritation.
• Overactive bladder (OAB) syndrome: a condition that causes urgency either with or without incontinence. It is caused by detrusor overactivity.
• Mixed incontinence: a combination of urge and stress incontinence.
• Overflow incontinence: urinary leakage due to either detrusor underactivity or chronic bladder outflow obstruction (BOO). Both can cause urinary retention and subsequent leakage. BOO is often due to prostate problems in men, which can lead to obstructive nephropathy secondary to back pressure.
• True incontinence: a fistula forms between the vagina and the ureter or bladder or urethra and predisposes to continuous urine leakage.

Urinary incontinence is more prevalent with age and is common in those living in institutions such as assisted living and care homes. Risk factors include high BMI, diabetes mellitus, pregnancy and childbirth, hysterectomy, multiparity, recurrent UTI, cognitive impairment, neurological disorders, and prostate disorders.

Assessment/Investigations

• Review medications as a possible cause for symptoms.
• Assess lifestyle factors, i.e., alcohol/caffeine intake, weight.
• Assess functional status, i.e., ability to access the toilet.
• Men: perform a digital rectal examination to assess the prostate and to rule out any other rectal pathology.
• Women: take a full obstetric history. Perform a vaginal/bimanual examination to exclude pelvic organ prolapse and assess the ability to initiate voluntary contraction of pelvic floor muscles, i.e., Kegel’s exercise.
• Urine dip and culture.
• Bladder diary/chart to be recorded by the patient (minimum 3 days).
• Urodynamic studies.
• Imaging: bladder scan (to assess post void residual volume to rule out voiding dysfunction). Ultrasound kidney ureter bladder is indicated in men and women with neurological conditions such as spina bifida/spinal cord injury, where renal complications may occur.

It is important to note that urinary incontinence associated with features suggestive of urological/gynaecological cancer should be referred via the two-week wait pathway. Symptoms to exclude:

• Men: lower urinary tract symptoms complicated with recurrent/persistent UTI, retention, renal impairment, persisting bladder or urethral pain and associated faecal incontinence.
• Women: constant leakage (possible urogenital fistula), previous pelvic radiation therapy, associated faecal incontinence, persisting bladder or urethral pain and pelvic masses.

Management

If stress incontinence is predominant:

• Pelvic floor muscle training: minimum 8 contractions performed 3 times/day for a minimum of 3 months. Continue if successful. Electrical stimulation and/or biofeedback in women who cannot actively contract pelvic floor muscles.
• Surgical treatment if conservative measures fail, i.e., open colposuspension or autologous rectus fascial sling.
• Duloxetine is used second line in women who do not want or are not surgical candidates. It increases the synaptic concentration of noradrenaline and serotonin within the pudendal nerve. This increases the stimulation of urethral sphincter striated muscles and enhances contraction.

If urge incontinence is predominant:

• Bladder retraining: minimum of 6 weeks involving pelvic muscle training, scheduled voiding intervals with stepped increases and suppression of urge with distraction or relaxation techniques.
• If bladder training alone is ineffective, antimuscarinics/anticholinergics can be offered as an adjunct, e.g., oxybutynin, tolterodine, solifenacin, and fesoterodine. They act by having a direct relaxant effect on urinary smooth muscle. Hence involuntary detrusor contractions are reduced, and bladder capacity is increased. Immediate-release formulations are more cost effective. However, extended-release formulations are associated with fewer side effects, such as dry mouth. Avoid these drugs in frail elderly women. An alternative is mirabegron – a beta-3 agonist of detrusor smooth muscle which promotes detrusor relaxation. It is avoided in patients with uncontrolled hypertension.
• Other treatment options include botulinum toxin injections.

In mixed incontinence, management is directed at the more predominant symptom; however, a combination of strategies can be used.

• Pelvic floor muscle training and bladder retraining are first line treatment.
• Drug treatment such as oxybutynin is the first line, but all antimuscarinics are equally effective. Oxybutynin should be avoided in the elderly as it impairs cognition. Newer antimuscarinics such as darifenacin, solifenacin, tolterodine and trospium are alternatives. Extended release or transdermal oxybutynin are other possibilities. Side effects include constipation, urinary retention, and confusion. Review annually, six months if over 75 years old.

Overflow incontinence:

• If secondary to bladder outlet obstruction, treat the cause, i.e., prostate hypertrophy, either benign or malignant.
• Intermittent self catheterisation, indwelling urethral or suprapubic catheterisation can be used.

Preventative measures include weight control, mainly for stress incontinence.

Hypothermia

Overview

Hypothermia is defined as a core body temperature <5 degrees Celsius. Low-reading thermometers, preferably oesophageal, are required as tympanic thermometers are unreliable in very low temperature states. It can be classified as primary or secondary.

Primary hypothermia is due to environmental exposure with no underlying medical condition that can cause thermodysregulation. Examples include trauma patients, whereby hypothermia is part of the lethal triad, coagulopathy, acidosis, and perioperative hypothermia, which may be deliberate or accidental.

Secondary hypothermia can arise from decreased heat production (hypopituitarism, hypothyroidism, severe malnutrition, hypoglycemia, hypoadrenalism), increased heat loss (burns, erythroderma, vasodilation due to toxic substances), impaired thermoregulation (Parkinson’s disease, multiple sclerosis, pancreatitis, cerebrovascular accident, prolonged cardiac arrest), drugs (beta blockers, neuroleptics, general anaesthetic agents) and other substances (ethanol, sedatives, hypnotics).

Risk factors include elderly patients, cognitive impairment, malnourished and multiple comorbidities.

Severity

• Mild: 32-35 degrees Celsius (lethargy, confusion, shivering, loss of fine motor coordination).
• Moderate: 28-32 degrees Celsius (delirium, slowed reflexes).
• Severe: <28 degrees Celsius (very cold skin, unresponsive, coma, difficulty breathing, arrhythmia).

Investigations

• Coagulation profile: disseminated intravascular coagulation may occur.
• ECG changes include bradycardia, ‘J’ wave (Osborn wave: small hump at the end of QRS complex), first degree heart block, long QT interval, atrial and ventricular arrhythmias.
• CXR: aspiration pneumonia, pulmonary oedema.

Management

The main principles are stabilising airway breathing and circulation, rewarming (warmed and humidified oxygen, heated IV saline, warm blankets, heat lamps), careful monitoring (ideally in an acute care setting) and treatment of complications such as cardiac arrhythmias. Assess and treat any underlying associated disorders, such as drug ingestion. Complications include multiorgan failure, metabolic acidosis, electrolyte imbalances and lethal arrhythmias. Overall mortality increases with the severity of hypothermia.