1 - Obesity & Thermal Injury Flashcards
What is the primary factor in the development of obesity?
genotype -environment also plays a role
-fat is considered an organ
___% of american adults have a BMI > 30
35%
BMI calculations
weight (kg)/Height (m^2)
(weight (lbs)/height (in^2) x 703
BMI Class & ASA)
25-29.9 = overweight
30-34.9 = obese class I
35 - 39.9 = obese class II
40-44.9 = obese class III / extreme (not morbid)
obese >45 = obese class IV/ severe
IBW
Broca’s index:
male = height (cm) - 100
female = height (cm) - 105
*may underdose obese because Vd is bigger
LBW
lean body weight = IBW x 1.3
*best to calc dose
Andriod
Apple heart disease, DM, HTN, dyspilidemia, death
Gynecoid
Pear varicose veins, joint disease
Obestiy: Cardiac
- increased metabolic demand
- increased CO (0.1 L/min for each kg of fat)
- increased workload to meet demand
What leads to HTN in the obese?
increased volume + RAAS activation
CAD
independent factor with obesity
HTN in obesity
SBP>140
DBP>90
OR BOTH (2x risk in obesity)
HTN and obesity characteristics…
increased: blood viscosity, mineralocorticoids, sodium reabsorption, RAA activation
And…hyperinsulinemia, comression of kidneys
Obesity: respiratory
- decreased compliance, FRC, ERV, VC, TLC
- F/V loop = restrictive
- increased dead space
- RV, CC, FVC and FEV1 dont change
- hypoventilation, hypercarbia, acidosis
OSA
definition: excessive episodes of apnea (10 sec) and hyponea.
>5 episodes per hour or 30/night
risk factor: BMI > 30, abdominal fat dist, large neck
- BMI>35 - OSA in 71-77%
- hypoxia, hypercapnia, systemi and pulm HTN, cardiac arrythmias
- gold standard - polysomnography
STOP-BANG
-93% sensitivity
Snoring
Tiredness
Observed apnea
high blood Pressure
BMI >35
Age
Neck (>40 cm)
Gender
0-2 = low risk
3-4 = Intermediate
>5 = high risk
Obese Hypoventilation (Pickwickian) Syndrome
- somnolence, cyanosis induced polycythemia, resp acidosis, R sided heart failure…
- elevated PaCO2
- right sided heart fail d/t hypoxic pulm vasoconstriction
DM
80% of NIDDM pts are obese, risk linear to BMI
Metabolic Syndrome
glucose intolerance, DM2, HTN, dyslipidemia, CVD
CV risk 50-60% above normal
Obesity: Pharmacology
-increased Vd (lipid soluble), increased blood volume, increased CO, decreased total body water, altered protein binding
IBW vs TBW
low lipophilicity = LBW, mainly goes to lean tissue
highy lipophilicity = TBW (usually), equal distribution to fatty and lean tissue, lipi soluble drugs
Obesity: GA and resp
- 50% reduced FRC compared to 20% in non-obese
- PEEP 6-10 ml/kg of IBW
Volume replacement - Obese
increased TBV, decreased estimated blood volume 45-55 ml/kg
1st degree burn
- limited to epidermis (superficial)
- heals spontaneously
2nd degree burn
- extends to dermis (deep/ superficial partial thickness)
- may need graft
3rd degree burn
- extend to subcutaneous (full thickness)
- skin grafting needed, no pain d/t nerve damage
4th degree burn
-muscle, fascia, bone -extensive
Major Burn
- 2nd degree = >10% for adults, >20% extremes of age
- 3rd degree = >10%
- electrical burn
- inhalation inolvement
Mortality estimate
age + TBSA% = (>115 moratlity is >80%)
double if inhalation
Rule of 9’s: infant
Rule of 9’s: adult
Rule of 9’s: child
Electrical Burn
myoglobinurea and renal failure
1st Phase of Burn Resuscitation
Dx and Tx of airway injury early intubation
succs ok in first 24 hrs
Succinylcholine
- denervation-like phenomenon
- proliferation of ACH receptors, K+ release
- no succs after 24 hrs, ok after wound closed and pt gaining weight
- resistnat to NMB agents d/t upregulatio of cholinergic receptors
CO Poisoning
CO binds to Hgb, 200x affinity more than O2
- tissues cannot extract oxygen
- disrupts oxidative phosphorylation
- metabolic acidosis at cellular level
- shift curve to the Left, pulse oximetry not accurate
CO Poisoning Treatment
100% oxygen decreases CO half life from 4 hrs to 40 min
Burns and Hypovolemic Shock
-fluid loss greatest in 1st 12 hrs, begins to stabilize after 24 hrs
Burns - fluid shifts from…
intravascular to interstitium
- leads to plasma depletion and hypovolemia
- edema
Fluid Resuscitation
Adults:
Ringers lactate 2-4 ml x kg x BSA%
Child:
Ringers lactate 3-4 ml x kg x BSA%
- half of estimated volume should be given in first 8 hours after burn. Remaining half should be given in subsequent 16 hrs
- infants and children should recieve fluid with 5% dextrose at maintenance rate in addition to resus fluid volume
Brooke Formula
First 24 hr:
crytalloid = 2 ml LR / % burn / kg crystalloid
(no colloid)
*half in first 8 hr, half in next 16 hr
Second 24 hr:
crystalloid = D5W maintenance rate AND
colloid = 0.5 ml / % burn / kg
Parkland Formula
First 24 hr:
crystalloid = 4 ml LR / % burn / kg
(no colloid)
*half in first 8 hr, half in next 16 hr
Second 24 hr:
crystalloid = D5W maintenance
colloid = 0.5 ml / % burn / kg
Minimum urinary output: Burns
Adults: 0.5 mL/kg/hr
Children weighing less than 30 kg: 1 mL/kg/hr
Pts w/ high voltage electrical injury: 1-1.5 mL/kg/hr
Hypermetabolic/ Hyperhemodynamic Phase
Usually after 48 hrs s/s: hyperthermia, tachypnea, tachycardia, increased serum catecholamines, increased oxygen consumption, increased catabolism, increased basal metabolic rate
hallmark of burn shock?
decreased CO -occurs w/i minutes
- inititally preserved by catecholamine (inc HR and vasoconstrict)
- losses overcome
- myocardial depressants released from burned tissue
Pulmonary Fx: Burns
- decreased overall function
- decreased chest wall compliance, FRC
- ventilation can increase from 6 L/min to 40 L/min
What is the leading cause of death in burn pts?
sepsis adults = 75%
peds = near 100%
Burns: Renal
ARF increases mortality r/t: hypovolemia, decreased CO, increased catecholamines
-myoglobinemia: sodium bicard for tx
Burns: GI/ Nutrition
- increased caloric requirement
- enteral feeds, stop 4 hrs for non-tubed, don’t stop if tubed
- do not stop TPN
Fluid & Blood replacement: Burns
- can be very bloody
- 200-400 mL EBL for each 1% debridement
Capacities:
FRC
ERV
VC
TLC
Decreased with obesity:
FRC = 2,500
ERV = 1,000
VC = 4,500
TLC = 5,500
Decreased FRC to < CC?
hypoxia, dead space increased, VQ mismatch, shunt
LBW meds
- propofol induction dose (loading dose determined by distribution)
- meaintenance of fentanyl and sufentanyl
*water soluble drugs
TBW meds
propofol maintenance (determined by clearance)
succinylcholine
suggamedex
loading dose of fentanyl, sufentanyl
*lipid soluble drugs
IBW
roc, vec, cis
remifentantyl
Anesthetia and burn pts…
- profound effect of agent due to hypovolemia
- NSAIDS - may inhibit platelet aggregation
highly lipophilic medications
digoxing, procainamide, remifentanil
