Anaesthesia for the Elderly Patient
Take home messages
- If you take nothing else away from this post - just try to keep their blood pressure within 20% of their baseline
- Preoperative anaemia is associated with worse perioperative outcomes
- Don't assume your drugs are going to work normally
It's all downhill from here
The first contentious decision is working out what exactly is deemed acceptable to label as 'elderly'.
From the fourth decade of life onwards, there is a measurable progressive and global decline in physiological function throughout the body.
This process then accelerates once a patient hits their seventies.
What are some of those changes?
Airway
- More likely to be missing teeth*
- Reduced oropharyngeal tone
- Stiff neck - cervical spondylosis and osteoarthritis
- Osteoporotic mandible
*I was once informed by a four-foot-three, eighty-five year old purple-haired lady who drank three litres of sherry per day, that "one is not old until one sleeps in a separate bed to one's teeth".
She'll probably outlive me.
Respiratory
- Stiffer lungs and chest wall
- Smaller lung capacities and volumes
- Increase in closing capacity*
- V/Q mismatch and widened alveolar-arterial oxygen gradient
- Increased incidence of chronic respiratory disease like COPD
- Chemoreceptors are less sensitive to hypoxia and hypercapnia
*The closing capacity matches functional residual capacity in the upright position by around 65 years, 44 years when supine.
Cardiovascular
- All cardiac comorbidities become more common with age - IHD, valve pathology, heart failure, conduction defects
- Pacemakers
- Reduced stroke volume and contractility - cardiac output drops by 20% by 60
- Lower maximum heart rate
- Stiffer ventricles (less compliant)
- Increased systemic vascular resistance
- Reduced myocardial response to catecholamines and sympathomimetic drugs due to reduced adrenergic receptor density
- Less sensitive baroreceptors - causing orthostatic hypotension
Neurological
- Cerebral atrophy - more than 10% reduction in brain mass
- Decreased neurotransmitter concentration
- Reduced cerebral blood flow
- Reduced cerebral oxygen consumption
- Decreased MAC requirement - about 5% per decade*
- Increased rates of delirium and dementia
- Visual and hearing impairment
- Poor balance
- Autonomic neuropathy - especially if diabetic
*This graph extrapolates to hit the x axis at 137 years of age.
The autonomic dysfunction is like a physiological beta blocker.
Gastrointestinal
- Slower gastric emptying
- Parietal cell dysfunction
- Hiatus hernia more common
- Gastro-oesophageal reflux more common
Renal
- Increased incidence of CKD and AKI
- Large prostates in elderly men cause obstructive renal injury
- Often dehydrated
- Renal fluid handling and concentrating ability is impaired - fluid overload and dehydration both more common
- GFR drops with age - by about 40% once you hit seventy
- Reduced drug clearance
Endocrine and metabolic
- Increased incidence of diabetes
- Increased incidence of thyroid disease
- Lower metabolic rate - drops by 1% per year after 30
- Impaired thermoregulation and reduced physiological response to cold
Musculoskeletal
- Reduced muscle mass
- Sarcopenia
- Increased body fat percentage
- Stiff joints
- Fragile skin
High Yield Exam Questions
What are the most common operations for elderly patients?
- Cataracts - day case under local anaesthetic usually
- TURP - general or spinal, with insidious blood loss and difficult fluid management
- Hip fracture - average age 80, often comorbid and frail patients who benefit from urgent surgery
Briefly summarise your anaesthetic considerations when anaesthetising an elderly patient.
I'm going to break this down into preoperative, intraoperative and postoperative considerations.
Preoperative
- History and examination may be more difficult if there are communication or cognitive issues
- May require collateral history and consenting with LPOA
- A cognitive assessment such as an MMSE is useful to establish baseline
- Bedside observations, particularly blood pressure as high risk of intraoperative hypotension
- Coexisting cardiovascular, respiratory, neurological, renal and endocrine disease is common - these need assessing and optimising where possible prior to surgery, ideally in an MDT setting
- Any operation carries higher mortality in the elderly - 75% of perioperative deaths occur in those over seventy (NCEPOD report)*
I would also like to have a pragmatic discussion about ceilings of treatment and escalation plans prior to the operation.
Intraoperative
- Airway concerns - see above
- Altered respiratory dynamics - see above
- Tight blood pressure control needed - consider arterial line
- Cautious use of intravenous fluid therapy
- Consider depth of anaesthesia monitoring with volatiles to allow lower MAC target
- Altered pharmacology - more sensitive to sedation and opioids, less sensitive to inotropes - see below
- Skin fragility and pressure point risk with stiff joints needs careful positioning and padding
Postoperative
- Increased length of stay
- Increased risk of VTE
- Increased risk of postoperative cognitive dysfunction
- Pain is more difficult to assess and makes all complications worse - delirium, cardiac, poor mobility and wound healing
- Multimodal analgesia, usually avoiding NSAIDS, to reduce opioid requirement is essential
- Ideally an MDT rehabilitation and recovery pathway with physio/OT/HCOOP
*90 day mortality is around four times higher after an emergency laparotomy for patients over 60 years of age.
Can you name any recommendations from the 2010 NCEPOD report on emergency and elective surgery in the elderly?
- Routine daily input from HCOOP team
- Comorbidity, Disability and Frailty need to be clearly recognised as independent risk factors in the elderly
- Delays in surgery worsen outcomes for elderly patients
- Elderly admissions should have a formal nutritional assessment during their hospital stay
- Temperature monitoring and management of hypothermia should be recorded in the anaesthetic chart
- Avoid intra-operative low blood pressure and consider non invasive cardiac output monitoring to facilitate this
- Comorbid elderly patients often need monitoring in HDU or ITU level settings
- Postoperative AKI is avoidable
- Pain should be treated with the same respect as blood pressure and heart rate
Frailty is a better predictor of poor outcome than age alone.
Have you heard of comprehensive geriatric assessment?
Yes.
- It is a holistic, multidisciplinary diagnostic process designed to determine a frail older person's medical, psychosocial and functional capabilities and limitations
- This is then used to build a personalised management plan
- It has shown to be a cost effective way to reduce mortality and morbidity in elderly surgical patients
An example would be the Peri-operative care of Older People undergoing Surgery service established in 2003.
There are many different varieties but they all assess parameters such as:
- Medical history
- Comprehensive medical examination
- Medications
- Balance and mobility - e.g. the 'Timed Up and Go' test
- Appetite and nutrition - e.g. MUST
- Continence and constipation
- Skin integrity and pressure areas
- Dentition
- Foot hygiene
- Frailty - e.g. Rockwood
Keep em warm
"Ooh it's cold in here" - literally every elderly patient upon walking into theatre.
If you consider the blanket:teeth ratio of most frail elderly patients sat at home, it's no wonder they're horribly susceptible to hypothermia when they come for an operation.
Not only do they have a less sensitive thermostat, they have less muscle mass to shiver and generate heat with when they do finally start to mount a metabolic response.
Hypothermia is associated with dramatically worse outcomes in any patient, and temperature in the elderly should be treated with the same reverence as it is in neonates.
Elderly pharmacology
Human pharmacology doesn't magically change above a certain age, but you need to be aware of how some drugs will be either more or less effective as your patient ages.
Imagine a patient pitches up for an operation, and informs you that they have some esoteric eponymous condition with the following effects:
- Drugs redistribute through their body differently
- They have less protein binding so more free fraction of drug is available to cause effects and side effects
- Their relatively higher body fat percentage will prolong the life of any lipophilic drugs you administer
- Their liver and kidneys break drugs down more slowly
- They have fewer receptors than normal, and they also react differently to the same drugs
- They're also taking a whole heap of drugs that affect their blood pressure, blood sugar, coagulation and also interact with loads of other drugs
You'd probably think rather carefully about how to anaesthetise them safely no?
Well this is what happens when people get older.
And we wonder why Mildred's still a bit saggy in recovery after blatting her with a whole syringe of sleep mayonnaise.
Some specifics to be aware of
Adrenergic drugs
- Reduced sensitivity to inotropes
- Reduced sensitivity to beta blockers
- Alpha agonist response is usually similar to that seen in younger patients, however remember Mr Octogenarian is probably taking tamsulosin for his prostate, which will compete for alpha receptor attention
- Ephedrine often does naff all in the elderly, so you might have more luck with metaraminol or phenylephrine
Opioids
- Age related increase of elimination half life
- Prolonged duration of action due to increased body fat percentage and reduced hepatic/renal clearance
Benzodiazepines
- Premedication with benzos can cause prolonged sedation
- Midazolam can cause paradoxical agitation when used for procedural sedation
Induction agents
- Induction dose requirement is lower
- This is due to reduced blood volume and reduced protein binding
- Induction will also take longer due to lower cardiac output
- Emergence is further slowed by slower redistribution and metabolism
Volatile agents
- MAC requirement drops steadily with age to around 40% less by 70 years old
- Sevoflurane gas inductions are often attractive options, as they are slower and maintain spontaneous respiration
Muscle relaxants
- Older people generally have less muscle mass, so you'd expect them to need less muscle relaxant
- Reduced cardiac output means time to intubating conditions is increased
- Reduced metabolism prolongs duration of block
- Drugs that are organ-independent such as atracurium are considered safer in elderly patients
Aim high
Elderly blood vessels are usually a little stiffer and used to a little more pressure than the supple vessels of their more youthful counterparts.
You can give some fluid, and often these patients are crispy dry after eight hours on the floor and another fifteen on the ward with an occluded IV pump screaming into their mercifully deaf left ear.
However you do risk circulatory overload if you try and manage neuraxial hypotension solely with fluids so just crank out some phenylephrine or metaraminol.
Regional or GA?
In the UK at least, there seems to be a knee-jerk (pun intended) assumption that an elderly #NOF is getting a spinal and sedation because 'regional is better'.
Hop over the pond to the US and they'll think you're mad for not GA'ing them all.
Long story short there isn't a whole heap of evidence in favour of either technique, but what really matters is tight blood pressure control and maintenance of all the other homeostatic variables that keep Margaret ticking.
- Spinals can cause more hypotension, but judicious use of pressors can mitigate against this
- If they took their aspirin, clopidogrel and apixaban this morning, maybe stay away from the spine?
- If their chest sounds like a tumble dryer eating gravel, then general anaesthesia may be a tad risky?
- If they've got communicating hydrocephalus with dementia, pulmonary fibrosis and severe aortic stenosis then you can't win either way
As always, there's no definitive right answer, just many, many ways to get it wrong.
Why is Geoffrey confused?
You've been called to see eighty-seven year old Geoffrey in recovery because he's confused and the recovery nurse is concerned.
Bearing in mind that on a good day, without a fractured hip and sixteen hours of sleep deprived dehydration, Geoffrey is confused by:
- Young people
- The internet
- Mobile phones
- Why creme eggs aren't as big as they used to be
It's no wonder that when you've ploughed him full of opioids, made half of his body feel like it's just disappeared and then woken him up in a different room to where he fell asleep and surrounded him with beeping monitors and smiling strangers, that he might be a smidge more confused than usual.
What is postoperative cognitive dysfunction?
A spectrum of deficits including:
- Short term memory loss
- Acute disorientation
- Confusion
- Longer-term personality changes
- Difficulties with tasks requiring organsiation of thought
25% of elderly surgical patients develop at least some degree of POCD.
What are the risk factors for POCD?
- Age
- Major or prolonged surgery
- Alcohol intake
- Substance abuse
- Infection
- Polypharmacy
- Pre-existing cognitive impairment
- Significant comorbidity and higher ASA grade
To prevent it:
- Avoid benzodiazepines
- Good analgesia
- Maintain sleep-wake cycle (if that's even possible in an NHS hospital)
- Early mobilisation
- Glasses/hearing aids
Read this for excellent extras
nigel.hollisterdoctors.org.uk
References and Further Reading
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