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Concepts 1 > Obese Patients > Flashcards

Obese Patients Flashcards

1
Q

Adipose Tissue

A

Secretes numerous proteins
Considered an endocrine organ
Reservoir for convertible and usable energy
Maintain heat insulation

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2
Q

Central, Android, Abdominal Visceral Obesity

A

“Apple Shaped”
Waist circumference greater than 102 cm (40 inches) in MEN
Waist circumference greater than 88 cm (35 inches) in WOMEN

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3
Q

Obesity causes increased risk for ___

A

Ischemic Heart Disease
Diabetes
HTN
Dyslipidemia
Death

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4
Q

Peripheral Gynecoid or Gluteal Obesity AKA ___

Associated with ___.

A

“Pear Shaped”
Associated with:
Varicose Veins
non-insulin dependent DM
Medical risks are DECREASED in individuals with Gynecoid fat distribution compared to android pattern

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5
Q

Cardiovascular Conditions Associated with Obesity

A

CAD
HTN
Dyslipidemia
Cerebrovascular disease
Thromboembolic disease
Cardiomegaly
Congestive Heart Failure
Pulmonary Hypertension

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6
Q

Respiratory Conditions Associated with Obesity

A

Restrictive lung disease
Obesity Hypoventilation Syndrome
Obstructive Sleep Apnea

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7
Q

Endocrine Conditions Associated with Obesity

A

Type 2 Diabetes
Thyroid disorders

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8
Q

Gastrointestinal Conditions Associated with Obesity

A
  • GERD
  • Nonalcoholic fatty liver disease, steatosis, cirrhosis, hepatomegaly
  • Hiatal or inguinal hernia
  • Gallbladder disease
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9
Q

Miscellaneous Conditions Associated with Obesity

A

Gout, Low back pain, Osteoarthritis
Infertility & Obstetric complications
Wound Infections
Pancreatitis
Urinary Incontinence
Malignancy: Esophageal, gallbladder colon, breast, uterine, cervical, prostate, renal

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10
Q

Respiratory Physiology

A

Increased work of breathing
Increase O2 consumption
Increased CO2 production and disordered ventilation to perfusion matching

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11
Q

Respiratory rates are ______ while functional Residual capacity and expiratory reserve volume are ________

A

Respiratory rates are increased while functional residual and expiratory reserve volume are decreased

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12
Q

What do the changes to the respiratory physiology in the obese patient mean to us as anesthesia providers?

A

Decreased time to desaturation during apnea
increased O2 requirements
Hypoventilation with supine spontaneous ventilation

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13
Q

What is Obesity Hypoventilation Syndrome (Pickwickian)?

A

A complication of extreme obesity characterized by:

  • hypercapnia
  • OSA
  • daytime hypersomnolence
  • pulmonary HTN
  • cyanosis-induced polycythemia
  • arterial hypoxemia
  • respiratory acidosis
  • right-sided heart failure

* 8% of obese patients have OHS

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14
Q

With Obesity Hypoventilation Syndrome, patients develop ___.

A

Nocturnal episodes of central apnea (apnea without respiratory efforts)—> progressive desensitization of respiratory centers to hypercarbia

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15
Q

Obesity Hypoventilation Syndrome (Pickwickian) is defined as ________________.

A

Patients with BMI >30kg/m2, who experience daytime hypoventilation with awake PCO2 greater than 45 and sleep disordered breathing in absence of other causes of hypoventilation

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16
Q

Cardiovascular Physiology for obese pts

A

Increased circulating blood volume, although it is a lower proportion of total weight (50 mL/kg as compared with 75 mL/kg) compared with patients with normal body mass index (BMI).

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17
Q

SVR in obese patients is ___

A

Decreased

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18
Q

Cardiac output in obese patients is ___

A

Increased by 20-30mL per kg of excess body fat

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19
Q

Stroke index, cardiac index and heart rate in obese patients = _____

A

remains normal

*The increased cardiac output results occurs by means of expanded stroke volume

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20
Q

Left ventricular hypertrophy is related to ____.

The increase in cardiac output can lead to ____.

A

the duration of obesity

EITHER left ventricular failure (associated with HTN) or Right heart failure (associated with hypoxia and hypercapnia of OSA)

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21
Q

Metabolic Syndrome Defintion

A

Presence of three or more of the following:

  1. Elevated waist circumference- Men 40 inches (102cm) or greater, Women 35 inches (88cm) or greater
  2. Elevated triglycerides- 150mg/dL or greater
  3. Reduced HDL Cholesterol- Men less than 40 mg/dL. Women less than 50 mg/dL.
  4. Elevated blood pressure- 130/85 or greater
  5. Elevated fasting glucose- 100mg/dL or greater
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22
Q

Metabolic, Endocrine, GI Considerations

A

GI: Incidence of GERD, gallstones, pancreatitis, and non-alcoholic fatty liver increases with obesity

Obesity increases risk of cardiovascular disease and T2DM

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23
Q

Pharmacologic Considerations: Dosing is generally based on __________ for bolus doses and ______________ for infusions or repeat boluses

A

Dosing is generally based on volume of distribution for bolus doses and on clearance for infusions or repeat boluses.

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24
Q

Volume of Distribution

A

The volume of distribution is increased for lipophilic drugs
Less lipophilic drugs have little change

*Meaning, if you’re giving a lipophillic drug, you most likely would need to give MORE agent in the obese patient than the non-obese patient.

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25
Q

Lipophillic Drug Clearance is generally ____________ in obese patients

A

higher

*You may see increased needs for infusions or repeat boluses. For prolonged infusions of lipophyllic drugs, you may want to d/c the infusion earlier since it will hang around in the tissue for longer potentially.

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26
Q

Pharmacologic Considerations for obese patients

A

Prolonged infusions of highly lipophilic drugs= prolonged half-life

Consider discontinuing earlier rather than later

(For prolonged infusion of highly lipophilic drugs, the t1/2 and drug effect may be markedly prolonged after discontinuation of the infusion, due to increased Vd)

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27
Q

Pharmacokinetics Changes Associated with Obesity

A
  • Increased fat mass
  • Increased cardiac output
  • Increased blood volume
  • Increased lean body weight
  • Changes in plasma protein binding
  • Reduced total body water
  • Increased renal clearance
  • Increased volume of distribution of lipid-soluble drugs
  • Decreased pulmonary function
28
Q

Body Mass Index

A

Accepted measure of body habits that describes adiposity normalized for height

29
Q

BMI Chart

A

Underweight = BMI less than 18.5
Normal = BMI 18.5-24.9
Overweight = BMI 25-29.9
Obesity Class I = 30-34.9
Obesity Class II = 35-39.9
Extreme Obesity Class III = greater than 40

30
Q

Ideal Body Weight

A

Weight associated with maximum life expectancy. Calculated from patient’s HEIGHT

Men= Height (cm)-100
Women= Height (cm)- 105
31
Q

Lean Body Weight

A

Difference between total body weight and fat mass
Sex-specific formula that includes height and weight
Accounts for weight increases= lean body mass increases as well

IBW x 1.3

reasonable to use LBW for most dosing except for lipophilic drugs- then use TBW

32
Q

Meds to give vs. not to give obese patients

A
  • Avoid long acting respiratory depressants like opioids and sedatives (due to the prevalence of sleep apnea in obese patients)
  • use short acting and minimal fat soluble drugs
  • Sevo and Des are great options (excellent recovery profile)
  • Nitrous can be safely used in patients where requirement of O2 does not preclude it’s administration
  • ALWAYS use a nerve stimulator**
  • ABX prophylaxis- obese patients are more at risk for infection
33
Q

Pharmacologic Considerations Propofol

A

Induction dose= LBW
Maintenance dose= TBW

Increased fat mass does NOT affect initial distribution/redistribution during induction

Cardiac depression at high doses is concerning

34
Q

Pharmacologic Considerations Succinylcholine

A

Intubating Dose= TBW

Increased fluid compartment and pseudocholinesterase levels require higher doses to ensure adequate paralysis

35
Q

Pharmacologic Considerations: Rocuronium, Vecuronium, Cisatricrium

A

All doses based on IBW

-Hydrophilic drugs given at IBW will ensure shorter duration and a more predictable recovery in respiratory challenged population

36
Q

Pharmacologic Considerations: Fentanyl, Sufentanil

A

Loading dose use TBW
Maintenance dose use LBW and response

Increased distribution volume and elimination times correlate with degree of obesity

37
Q

Pharmacologic Considerations Remifentanil

A

Infusion rates use=IBW

Distribution volumes and elimination rates are similar to normal-sized individuals: fast offset requires planning for postoperative analgesia

38
Q

Pharmacologic Considerations Dexmedetomidine

A

Infusion rate 0.2mcg/kg/hr

Useful as an adjunct- lower than usual infusion rates are recommended to minimize adverse cardiac events

39
Q

Pharmacologic Considerations Sugammadex

A

Use TBW

no change from usual dosing is required

40
Q

Special Equipment Needs for Obese pts

A
  • Large and/or high weight capacity beds and operating tables
    • Designated weight limits for operating tables may not remain valid if the patient is shifted on the table, the table is positioned other than level (eg, Trendelenburg, reverse Trendelenburg, lateral tilt), or the table is unlocked. Additional arm supports to widen the table may be necessary.
  • Mechanical transfer mechanisms (ex. inflatable lateral transfer mattress)
  • Additional Personnel
  • Extra-long needles
  • Ultrasound
41
Q

Preanesthetic Evaluation Cardiac

A
  • Need an ECG- for determination of resting rate, rhythm, and ventricular hypertrophy or strain.
    • Axis deviation and atrial tachyarrhythmias are relatively common
  • Investigation of prior myocardial infarction and the presence of hypertension, angina, or peripheral vascular disease is crucial.
  • Limitations in exercise tolerance, history of orthopnea, and paroxysmal nocturnal dyspnea may indicate left ventricular dysfunction.
  • Exercise testing may elicit valuable information, but might not be feasible
42
Q

Pre-anesthetic Evaluation: respiratory

A

OSA, orthopnea, wheezing, sputum production, or smoking history.

Airway evaluation (assesses for potential for difficult mask ventilation)

  • Redundant tissue around the neck (restricting neck motion) and fat in the airway (decreasing glottic opening) together increase the difficulty of successfully intubating the trachea.
  • A neck circumference of 40 cm was associated with 5% likelihood difficult intubation and that increases to 35% for circumference 60cm or greater.
  • Awake intubation and the need for postoperative ventilation.
43
Q

Anesthetic Management: Monitoring

A

BP Cuffs that encircle a minimum of 75% of the upper arm should be used

Forearm measurements OVERESTIMATE both systolic and diastolic bp

Consider and A-line

44
Q

Airway Equipment Needed

A

Obese patients are more likely to require intubation:

Patients with BMI >40 kg/m2
Patients with primarily abdominal obesity
Major abdominal or thoracic surgery
Most surgery lasting >2 hours
Head down positioning
Confirm availability and access to difficult mask and intubation equipment

45
Q

Airway Management

A
  • head elevated laryngoscopy position (HELP)
  • towels under the patient’s shoulders and head, and putting the patient in the reverse Trendelenburg position to increase the patient’s FRC.
  • This creates a horizontal line connecting the patient’s sternal notch with the external auditory meatus.
46
Q

The HELP position creates a horizontal line connecting the patient’s ____________with the _____________.

A

-The HELP Position creates a horizontal line connecting the patient’s sternal notch with the external auditory meatus.

47
Q

Intubation PEARLs for obese pts

A
  • The airway should be secured expeditiously as patients with obesity desaturate quickly (r/t decrease FRC and increase oxygen requirements)
  • maximize O2 content in the lungs, patients are preoxygenated with a 100% mask O2 for at least 3 to 5 minutes with continuous positive airway pressure (CPAP)
  • Afterward preoxygenation, nasal O2 may be used for apneic diffusion oxygenation during intubation
  • In the setting of cannot intubate and cannot ventilate, a difficult algorithm should be used
48
Q

Rapid Sequence Induction

A

A rapid-sequence induction should be reserved for patients with a known aspiration risk

Ultrasonography of the stomach has been proposed as a tool for clinicians to identify obese patients at risk for aspiration.

If cricoid pressure is used: 20 Newtons (N), and that the force can be increased to 30 N as loss of consciousness occurs.

49
Q

Ventilation and Oxygenation Management

A
  • GA causes a 50% reduction in FRC in the obese anesthetized patient (only 20% in nonobese patients)
  • The addition of PEEP of 10 achieves an improvement in both FRC and arterial O2 tension, but only at the expense of cardiac output and O2 delivery.
  • Ventilation recommendations include using tidal volumes of 6–10 mL/kg of IBW to avoid barotrauma.
  • Pressure- or volume-controlled ventilators can be used to maintain adequate oxygenation and normocapnia.
  • The intermittent manual application of large volume “sighs” can also augment the FRC.
50
Q

Ventilation Management: Goals and Recommendations to Prevent Hypoxemia

A

HOB Elevated 30 degrees (reverse trend back-up Fowler)
Use CPAP during induction
Preoxygenate with 100% O2
If O2 Sat is < or equal to 95% performa. blood gas

51
Q

Ventilation Management: Goals and Recommendations to Prevent/Reverse Atelectasis

A

Restrict the use of FIO2 to less than 0.8 during maintenance

Recruitment maneuvers after intubation by using sustained 8-10 sec pressure of 40 cm H2O or greater- monitor for side effects- hypotension and bradycardia

Uses of high FIO2= accelerates atelectasis

52
Q

Ventilation Management: Goals and Recommendations to Maintain Lung recruitment

A

Use PEEP (10-12)

monitor for hypotension and decreasing arterial O2

53
Q

Ventilation Management: Goals and Recommendations to Prevent reoccurrence of Atelectasis

A

Intermittent intraoperative re-recruitment

Monitor higher oxygenation and respiratory system compliance achieved after recruitment

54
Q

Ventilation Management: Goals and Recommendations to Avoid Lung Overdistention

A

Use tidal volume of 6-10 mL/kg of IDEAL BODY WEIGHT

Keep end-inspiratory pressure below 30cm H2O

Consider mild permissive hypercapnia if necessary

-Increase the ventilation rate to control excessive hypercapnia instead of using larger tidal volumes or high ventilatory pressures

55
Q

Ventilation Management: Goals and Recommendations to Maintain Postoperative Lung Expansion

A
  • Use CPAP or BiPAP immediately after extubation
  • Administer supplemental O2
  • Keep upper body elevated
  • Maintain good pain control
  • Use incentive spirometer
  • Encourage early ambulation
56
Q

Volume Replacement

A
  • The normal adult percentage of total body water is 60%. In the severely obese, it is reduced to 40%.
  • Therefore, calculation of estimated blood volume should be 50 mL/kg of actual body weight rather than the 70 mL/kg apportioned in nonobese adults.
57
Q

Intraoperative Positioning

A
  • Positioning of obese requires extra precautions for the prevention of nerve, integumentary, and cardiorespiratory compromise.
  • Risk for nerve injury is INCREASED in the patient with obesity
  • Patients with obesity often have decreased ROM, assess preoperatively
  • Extra-long straps and wide adhesive tape can secure the panniculus and reduce shifting when the operating table is changed.
58
Q

The risk of airway obstruction after extubation is ___________ in obese patients.

A

Increased

59
Q

Extubation

A

Confirm appropriate reversal of NMBA

Extubate sitting up or head of bed up

Leave ETT in place if patient is not breathing adequately- extubate over an airway exchange or via fiberoptic bronchoscope may be performed

59
Q

Pain Management

A

Use non-opioids when possible: NSAIDs, patient-controlled analgesia, local infiltration of the surgical site, and epidural anesthesia.

Obese patients are more sensitive to the respiratory-depressant effects of opioid analgesics

Consider applying patient’s CPAP machine in the early post–general anesthetic period.

Postoperative opioids must be used judiciously

60
Q

How should SRNAs guide their management of drugs in obese patients?

A
  • no clear way exactly, limited literature
  • When possible and appropriate, anesthetic medications should be titrated to effect with incremental doses or incrementally adjusted infusions.
  • Modified drug dosing may be required because of obesity-related increases in lean body weight (LBW), cardiac output, and blood volume.
61
Q

What medications should you ask about in the obese pt population?

A
  • Weight reducing substances, herbal supplements, and anorexiant drugs
  • Insulin and oral hypoglycemic dosing may be held or decreased on the day of surgery
  • Most cardiac medications (except ACEI and ARBs) should be continued up to and including the morning of surgery.
62
Q

What labs should be drawn for obese pts?

A

•Should focus on comorbid disease states such as renal, hepatic, cardiovascular, and endocrine states related to obesity.

63
Q

OR Beds for obese pts

A
  • Newer-model operating room tables - 600 lb.
  • Older-model standard operating room tables - 300 lb
64
Q

For Succinylcholine, use ____.

For Nondepolarizing NMBAs, used for maintenance use ___.

A

For Succinylcholine, use TBW

For Nondepolarizing NMBAs, used for maintenance use IBW

65
Q

STOP BANG

A
  1. Snoring: do you snore loudly?
  2. Tired: do you often feel tired
  3. Observed: has anyone observed you stop breathing during sleep?
  4. Blood Pressure: do you have or being treated for HTN?
  5. BMI > 35?
  6. Age >50?
  7. Neck circumference >40cm2
  8. Gender, male?

High risk = yes to 3 or +

Low risk = yes to fewer than 3

66
Q

The STOP-Bang screening tool has a senitivity of ___.

A

up to 93% for OSA

Concepts 1 (10 decks)

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