Risk Factor Bucket Study Tool

Built to compare and contrast the recurring values, cutoffs, and risk-factor patterns across your obesity, ortho, lap/robotic, spine, and discussion lectures.
How to use this: start with High-Yield Repeats, then flip through the buckets. This is designed to help you notice patterns like “male vs female,” “older vs younger,” and “40 means two different things depending on context.”
Same number, different meaning

The number 40 shows up a lot

  • 40 inches = metabolic syndrome waist cutoff for men.
  • ≥ 40 kg/m² = class III obesity.
  • > 40 degrees lumbar scoliosis = surgery correlate.
  • 40% = approximate decrease in lung compliance with steep Trendelenburg / 45° head-down note.
Male vs female split

Watch for sex-based thresholds

  • Metabolic syndrome waist: men 40 in, women 35 in.
  • Metabolic syndrome HDL: men ≤ 40, women ≤ 50.
  • IBW shortcut: height cm − 100 men, − 105 women.
  • PBW formula differs: 50 base for men, 45.5 base for women.
Big repetitive exam values

Fast list

  • Tourniquet pressure: about 100 mmHg above SBP.
  • Tourniquet max inflation in lecture: 2 hours.
  • Beach chair: 0.75 mmHg drop per cm above the heart.
  • Low tidal volume: 6–8 mL/kg IBW in lap/robotic; 6–8 mL/kg PBW in obesity ventilation slides.
  • Estimated blood volume in obese lecture/discussion: 50 mL/kg.
High-yield compare

Which problems go with which contexts?

  • Male is a POVL risk factor; female is a PONV risk factor.
  • Older age > 60 raises VTE risk in ortho; young raises PONV risk compared with elderly.
  • Obesity raises VTE / OSA / rapid desaturation risk; decreased BMI was noted as a risk factor for subcutaneous emphysema in the lap lecture.
Male-associated

Male → think of these

  • Metabolic syndrome waist cutoff: ≥ 40 in.
  • Metabolic syndrome HDL cutoff: ≤ 40 mg/dL.
  • IBW shortcut: height cm − 100.
  • PBW base: 50.
  • POVL risk factor: male gender.
  • Android/central obesity is more common in males.
  • Scoliosis surgery incidence note: female > male (4:1), so male is the contrast there.
Memory cue
Men get the “40 and 40” metabolic syndrome pair: waist 40, HDL 40.
Female-associated

Female → think of these

  • Metabolic syndrome waist cutoff: ≥ 35 in.
  • Metabolic syndrome HDL cutoff: ≤ 50 mg/dL.
  • IBW shortcut: height cm − 105.
  • PBW base: 45.5.
  • PONV risk: female > men.
  • Scoliosis incidence in the spine lecture: female > male, 4:1.
  • Female gender is NOT the significant POVL risk factor in your discussion question.
Memory cue
Women get the “35 and 50” metabolic syndrome pair: waist 35, HDL 50.
Older age

Older / elderly tends to increase

  • VTE risk in ortho: > 60 years.
  • Subcutaneous emphysema risk: increased age.
  • POVL risk age buckets: < 18 or > 65.
  • Ankylosing spondylitis risk increases with age.
Younger age

Younger tends to increase

  • PONV risk: young > elderly.
  • Your robotic discussion specifically marked younger age as not a subQ emphysema risk factor in that question stem.
BMI buckets

Obesity classification

ValueMeaning
< 18.5Underweight
18.5–24.9Normal
25.0–29.9Overweight
30.0–34.9Class I obesity
35.0–39.9Class II obesity
≥ 40.0Class III obesity
≥ 50.0Super obesity
≥ 60.0Super-super obesity
When BMI means risk

High vs low BMI

  • High BMI → obesity physiology, rapid desaturation, VTE risk, positioning challenges, peripheral nerve injury risk in laparoscopy, outpatient risk factors, OSA/OHS concern.
  • BMI > 30 + awake PaCO2 > 45 = OHS concept.
  • BMI ≥ 50 was noted as generally unsuitable for outpatient surgery in the obesity lecture.
  • Decreased BMI was listed as a risk factor for subcutaneous emphysema in the lap lecture.
Neck / waist / screen values

Anthropometric values that get mixed up

  • STOP-Bang B = BMI, A = Age, not android obesity.
  • People often confuse 40 cm neck from STOP-Bang style memory with 40 in male waist from metabolic syndrome.
  • Central obesity uses waist circumference, not neck circumference.
Fast contrast
40 cm neck = OSA screening vibe. 40 in waist = male metabolic syndrome.
Weight formulas

Common formulas

  • IBW men = height cm − 100
  • IBW women = height cm − 105
  • LBW = IBW × 1.3
  • PBW men = 50 + 0.91 × (height cm − 152.4)
  • PBW women = 45.5 + 0.91 × (height cm − 152.4)
  • TBW = actual weight
Metabolic syndrome

Diagnosis = 3 of 5

  • Waist: men 40 in, women 35 in
  • Triglycerides: ≥ 150
  • HDL: men ≤ 40, women ≤ 50
  • Blood pressure: ≥ 130/85 or meds
  • Fasting glucose: ≥ 100 or meds
OSA / OHS

Numbers that matter

  • OHS discussion threshold: BMI > 30
  • OHS hypercapnia: awake PaCO2 > 45 mmHg
  • STOP-Bang trap: A = Age
Tourniquet

Tourniquet values

  • Inflation pressure: ~100 mmHg above SBP
  • Max inflation in lecture: 2 hours
  • Discussion nuance: notify surgeon at 60 min, common recs 60 min UE / 90 min LE, then deflate for 15 min before reinflation
Beach chair / position

MAP / pressure values

  • 0.75 mmHg drop in MAP per 1 cm above the heart
  • 20 cm above the heart ≈ 15 mmHg drop
  • External auditory meatus is the reference level for cerebral perfusion in higher-risk beach chair situations
Ventilation / respiratory

Ventilation values

  • Low tidal volume: 6–8 mL/kg IBW in lap/robotic
  • Obesity ventilation slide: 6–8 mL/kg PBW
  • PEEP: 5–10 cm H2O
  • Plateau pressure target note in obesity lecture: < 30 cm H2O
Other repeated values

Grab-bag numbers

  • EBV in obese lecture/discussion: 50 mL/kg
  • Steep Trendelenburg note: 45° head-down can decrease lung compliance by about 40%
  • Scoliosis surgery correlation: thoracic > 50°, lumbar > 40°
  • POVL spine risk lecture: surgery > 5 hrs, EBL > 1 L
  • VTE risk lecture: procedure > 30 min, immobilization > 4 days
Beach chair

High-yield associations

  • ↓ cerebral perfusion pressure risk
  • Hypotensive bradycardic episodes / Bezold-Jarisch reflex
  • MAP correction: 0.75 mmHg/cm above heart
  • POVL risk factor
Prone

High-yield associations

  • POVL risk factor
  • Ears / eyes / nose checks q15 min note
  • Abdominal / thoracic pressure can reduce venous return and cardiac output
Steep Trendelenburg

High-yield associations

  • ↑ MAP, ↑ CVP, ↑ SVR
  • ↑ ICP and ↓ cerebral venous drainage
  • ↑ airway edema
  • ↓ lung compliance, ↑ airway resistance, ↑ EtCO2
Time-based risk

Long case = more bad things

  • Subcutaneous emphysema risk ↑ with prolonged operative time
  • POVL risk ↑ with long spine case
  • Positioning injury risk ↑ with prolonged Trendelenburg / robotic cases
  • Tourniquet nerve damage risk ↑ when prolonged
EtCO₂ bucket

What raises vs lowers EtCO₂?

  • Increase: tourniquet deflation, CO₂ absorption, pneumoperitoneum hypercarbia
  • Decrease: BCIS, fat embolism under GA, venous gas embolism, severe cardiopulmonary compromise
Airway / aspiration

What makes aspiration more likely?

  • Obesity: delayed gastric emptying, GERD, hiatal hernia, high gastric volume, low pH
  • Bariatric surgery: treat as full stomach
  • GLP-1 was bonus content, not exam-weighted for your current test
Male vs female trap

Don’t mix these up

  • Female → PONV risk
  • Male → POVL risk
  • Female 4:1 → scoliosis incidence
High vs low BMI trap

Don’t overgeneralize BMI

  • High BMI causes many positioning/oxygenation/VTE problems
  • Lower BMI was still the risk factor named for subQ emphysema in your lap lecture stem