Obesity & Geriatrics Flashcards
What is Brocas formula? (2)
- Calculates IBW
- Men = height (cm) - 100
Women = height (cm) - 105
How is adjusted bodyweight calculated?
IBW + 40%
What changes do you find in respiration in obese patients? (6)
- Reduced functional residual capacity (from normal of 2L to 1L if BMI >40)
- increased atalectasis
- resting metabolic work, working of breathing of minute oxygen demand higher
- Therefore will desaturate rapidly when apneoc
- Can also have ‘wheeze’ do to airway closure
- OHA/OHS
In terms of type of obesity, what is more high risk?
Central obesity (waist > 50% height)
- increased airway/ventilation risk
- increased CVS disease
- increased metabolic syndrome
What occurs to the cardiovascular system in obesity?
SV/CO/blood volume all increase leading to both pulmonary and systemic HTN
What is the max load of a scoop?
227 kg
What is the max load of a normal stretcher?
191kg (30 st)
What is the max load of a bariatric stretcher?
268kg (50 st)
What drugs use lean body weight (or IBW)? (8)
- Propofol induction
- Ketamine
- Non-depolarising paralytics (rocuronium)
- Morphine
- Fentanyl/alfentanil
- Paracetamol
- LA
- Thiopentone
What medication use adjusted body weight? (3)
- Propofol infusion
- Suggamedex
- Gentamicin
What medications use total body weight? (5)
- Suxamethonium
- Midazolam
- LMWH
- Atropine/glycopyrronium
- Neostigmine
What BMI equates to:
1. Underweight
2. Healthy weight
3. Overweight
4. Obese
5. Class 1 obesity
6. Class 2 obesity
7. Class 3 obesity
- < 18.5 kg/m2
- 18.5-24.9
- 25-29.9
- > 30
- 30-34.9
- 35-39.9
- > 40
How is BMI calculated?
Weight (kg) / height (m)
Which class of weight has highest mortality?
Underweight
How is central adiposity measured?
Waist:height ratio
Waist (cm or inch) / height (cm or inches)
In both children/adults and women/men <35 BMI, which waist:height ratio is: (NICE)
1. Healthy
2. Increased central adiposity
3. High central adiposity
- 0.4-0.49
- 0.5-0.59
3 > 0.6
i.e. your waist should be less than half of your height
How does WHO define central obesity in:
1. men
2. women
3. Asian population
- Waist > 102cm
- Waist > 88cm
- > 90cm men, > 80cm women
What measurement is used for central adiposity/obesity in:
1. NICE
2. WHO
- Waist:height ratio
- Measurement waist in cm
Why do we ramp patients?
Increases FRC and reduces risk of aspiration
Why do obese patients have increased risk of awareness during RSI?
Larger volume of distribution so IV induction agents rapidly redistribute (increased FW) - initial affect similar to non-obese but will last less long and therefore should be quickly followed up with maintenance
What is total body weight?
TBW = LBW (lean body weight) + FW (fatty weight)H
How is lean body weight calculated?
Complex calculation (few different ones)
What is:
- TBW
- LBW
- IBW
- ABW
- LBW + FW
- LBW = patients weight excluding fat
- What patient should weight with normal lean:fat mass
- Takes into account obese patients have an increase lean body mass and increased volume distribution drugs
What type of weight should be used for emergency drugs (adrenaline/noradrenaline)
IBW
What weight calculation should be used to calculate TV
IBW
What percentage of the population are obese and what population is class 3 obesity?
25% and 3%
What are the components of metabolic syndome?
- HTN
- insulin resistance
- high cholesterol
- central obesity
What is the triad that makes OHS?
- BMI >35
- OSA
- Chronic daytime hypercapnia (>6Kpa)
What are the CV changes seen in the elderly? (7)
- Increased SVR secondary to decreased compliance of medium/large vessels.
- Reduced response to adrenaline/metaraminol secondary to the above
- LVH secondary to HTN and impaired diastolic filling secondary to collagen/fibrous deposition
- Pre-load increases initially to maintain CO however heart now works on flatter part of Starling curve therefore decreased physiological reserve
- Downregulation of myocardial catecholamine receptors therefore decreased response to catecholamines and sympathominetic agents. Decreased maximal HR and CO with age as a result
- Fat infiltration/fibrosis leads to decreased functioning of cardiac conducting pathways leading to increased AF etc.
Describe the respiratory changes that occur in elderly patients
- Reduced airway elastance, lung compliance and chest wall compliance
- Total lung capacity, FVC, FEV1 and vital capacity all reduce
3.Conversely residual volume and therefore FRC increase leading to Increased tendency of the alveoli and terminal airway collapse - Decreased chemoreceptor function leading to decreased response to hypoxia/hypercapnia
- Loss of airway tone and cough reflex
- Increased OSA
What is ‘Time Up and Go?’
Used to measure mobility in elderly - take to stand up, walk 3 m, turn around and return to sit back in chair
Describe the clinical frailty score (9)
