ANAESTHETICS AND AIRWAY
OBESITY
PromptHow does obesity effect assessment/management of airway
ResponseIncreased upper airway soft tissue - difficult intubation/airway maintenance
Increased pulmonary artery occlusion pressure - increased by high intraabdominal and pleural pressure
Increased pulmonary artery pressure - mild to moderate elevation may result from OSA alone
Decreased Total lung capacity
Decreased Vital capacity
Decreased functional residual capacity - atelectasis and reduced oxygen stores increase propensity for desaturation
Increased pleural pressure - reflects chest wall compression
Decreased respiratory system compliance, stiffer respiratory system likely from lung and chest wall contribution
Increased airway resistsnace - risk of asthma and airway closure
Decreased hypercapnoeic ventilateroy response - contributes to obesity hypoventilation syndrome
Increased upper airway resistance. Contributes to difficult airway and sleep apnoea
Neck fat = difficult FONA
The model answer was straight from LITFL!
Increased pulmonary artery occlusion pressure - increased by high intraabdominal and pleural pressure
Increased pulmonary artery pressure - mild to moderate elevation may result from OSA alone
Decreased Total lung capacity
Decreased Vital capacity
Decreased functional residual capacity - atelectasis and reduced oxygen stores increase propensity for desaturation
Increased pleural pressure - reflects chest wall compression
Decreased respiratory system compliance, stiffer respiratory system likely from lung and chest wall contribution
Increased airway resistsnace - risk of asthma and airway closure
Decreased hypercapnoeic ventilateroy response - contributes to obesity hypoventilation syndrome
Increased upper airway resistance. Contributes to difficult airway and sleep apnoea
Neck fat = difficult FONA
The model answer was straight from LITFL!
PromptPreparation to intubate patient in respiratory extremis
ResponseAvoid distressing patient
Establish and secure IV access
Prepare difficult airway trolley at bedside
Videolaryngoscope + Suction
Pre-oxygenate 100% FiO2 and PEEP if tolerated via NIV
Fluid bolus 500 mL N/S to reduce HR <100, SBP >100
Prepare patient in ramped position aiming for ear to sternoclavicular notch. Keep in semi-upright position in order to facilitate ventilation
Drugs - ketamine 1mg/kg + roc
Adrenaline infusion ready (commence 10 mics/min) predicting hypotension at induction
Broad spectrum ABx cover CAP
Inform ICU needing bed
Establish and secure IV access
Prepare difficult airway trolley at bedside
Videolaryngoscope + Suction
Pre-oxygenate 100% FiO2 and PEEP if tolerated via NIV
Fluid bolus 500 mL N/S to reduce HR <100, SBP >100
Prepare patient in ramped position aiming for ear to sternoclavicular notch. Keep in semi-upright position in order to facilitate ventilation
Drugs - ketamine 1mg/kg + roc
Adrenaline infusion ready (commence 10 mics/min) predicting hypotension at induction
Broad spectrum ABx cover CAP
Inform ICU needing bed
PromptRamping in obese patients
ResponseHead elevated laryngoscopy position, 1-2 pillows under head
Improves laryngoscopic view (POGO)
Allows breasts/chest to sit lower, improving ability to manipulate laryngoscope handle
Allows abdominal contents to sit lower, improving diaphragm excursion and ventilation >> improved pre-oxygenation and longer time to desaturation.
Improves laryngoscopic view (POGO)
Allows breasts/chest to sit lower, improving ability to manipulate laryngoscope handle
Allows abdominal contents to sit lower, improving diaphragm excursion and ventilation >> improved pre-oxygenation and longer time to desaturation.
PromptObesity effects on drug pharmacokinetics
ResponseAbsorption
Increased PO absorption (decreased gastric emptying time)
Difficult IV access, S/C absorption poor with decreased blood supply. IM may fail if needles too short
Distribution
Markedly affected by increased adipose tissue:lean body mass
Lipid soluble drugs Increased Vd
Water soluble drugs no change in Vd
Accumulation of lipophilic drugs in fat
Metabolism
Reduced hepatic bloodflow
Variable effects
Elimination
Lipid soluble drugs accumulate >> prolonged halflife
Increased GFR (normal kidneys in obese) vs concurrent renal disease >> altered elimination of renally cleared drugs
Model answer from LIFTL rather than being directed
Increased PO absorption (decreased gastric emptying time)
Difficult IV access, S/C absorption poor with decreased blood supply. IM may fail if needles too short
Distribution
Markedly affected by increased adipose tissue:lean body mass
Lipid soluble drugs Increased Vd
Water soluble drugs no change in Vd
Accumulation of lipophilic drugs in fat
Metabolism
Reduced hepatic bloodflow
Variable effects
Elimination
Lipid soluble drugs accumulate >> prolonged halflife
Increased GFR (normal kidneys in obese) vs concurrent renal disease >> altered elimination of renally cleared drugs
Model answer from LIFTL rather than being directed
PromptNIBP cuff technique in the obese
ResponseCommon for inaccurate NIBP with inappropriate cuff size (Overestimation in small cuff)
Bladder should be ~80% of arm circumference, width at least 40% of circumference
Place midline of cuff over upper arm brachial pulse. Should have 2-3cm for steth in cubital fossa
Summarised from essay long answer
Bladder should be ~80% of arm circumference, width at least 40% of circumference
Place midline of cuff over upper arm brachial pulse. Should have 2-3cm for steth in cubital fossa
Summarised from essay long answer