Quiz 9 - One Lung Ventilation and Malignant Hyperthermia

Question 1

During lung surgery the dependent lung is the lung that is down or up?

Answer 1

Down

Question 2

During lung surgery, which lung is nondependent?

Answer 2

the upper lung

Question 3

During lung surgery, where do you want to avoid placing the axillary roll?

Answer 3

in the axilla. The roll should be placed along the upper chest.

Question 4

Why should you restrict IVF during lung surgery?

Answer 4

Restrict IVF to basic maintenance to avoid gravity dependent fluid transudation to dependent lung and edema to the collapsed lung

Question 5

When you are awake and in a lateral position, which lung is better perfused and ventilated?

Answer 5

The dependent lung

Question 6

During surgery where a pt is in a lateral position, which lung will be better ventilated? Is this a problem?

Answer 6

The nondependent lung will be better ventilated but the dependent lung will be better perfused causing a VQ mismatch

Question 7

Due to the V/Q mismatch during open pneumothorax surgery, a _______ to _____% right-left intrapulmonary shunt occurs.

Answer 7

20-30%

Question 8

Hypoxic Pulmonary Vasoconstriction can worsen a right-left shunt (T/F)

Answer 8

False, it will improve the V/Q mismatch by shunting blood from the nonventilated, nondependent lung to the dependent lung.

Question 9

What factors can inhibit hypoxic pumonary vasoconstriction (HPV)?

Answer 9

Hypocapnea
Vasodilators (NTG, Nipride, Dobutamine, Ca channel blockers)
Inhalation agents

Question 10

Should you reduce your tidal volume during one lung ventilation?

Answer 10

NO, keep the Vt around 10cc/kg

Question 11

During apneic periods, how fast will the PCO2 incr3ease in the first minute and every minute after that? (if you are giving ample amount of O2)

Answer 11

It will rise 5mmHg in first minute and 3mmHg for each additional minute

Question 12

If using apnea during surgery, what is the time limit of the surgery due to progressive resp acidosis?

Answer 12

Limited to 10-20 min

Question 13

During one lung surgery where do you what to keep your FIO2 level?

Answer 13

80-100%

Question 14

During one lung ventilation, add ____ cmH2O CPAP to the nondependent lung and _____cm H2O PEEP to the dependent lung. Increase both slow

Answer 14

5 cm H20 for both

Question 15

Which double lumen ETT is most commonly used for one lung ventilation, a left or right?

Answer 15

Left - easier to place since you don’t have to worry about aligning an opening with the right upper lobe bronchus.

Question 16

What are some common triggers for Malignant Hyperthermia?

Answer 16

Succinylcholine and inhalation agents.

Other possible triggers could be stress, muscle trauma, exercise and heat stroke.

Question 17

What is the first sign of MH?

Answer 17

unexplained tachycardia

Question 18

What is the most specific sign of MH?

Answer 18

Increasing ETCO2 (hypercapnea), also decrease SaO2 and SpO2

Question 19

What are some other signs of MH?

Answer 19

Rigid muscles despite relaxants, dysrhythmias, tachypnea, cyanosis, sweating, unstable BP, mottled skin, trismus (masseter spasm), and more…

Question 20

Who has a greater incidence of MH, children or adults?

Answer 20

Children (1:12,000) vs adults (1:40,000 with succs, 1:220,000 without succs)

Question 21

Who is susceptible to MH?

Answer 21

persons with musculoskeletal issues, closely related family members of persons with known MH, Duchenne’s muscular dystrophy, King-Denborough syndrome

Question 22

What is the first thing you should do if you suspect MH during a case?

Answer 22

Stop all triggering agents then call for help

Question 23

What is the doseage for Dantrolene during MH?

Answer 23

2.5mg/kg IV ASAP then repeat q 5 min up to 10mg/kg (mixed in sterile H2O)

Question 24

During a case of MH, what else should you do/give besides Dantrolene?

Answer 24

Hyperventilate with 100% O2
give Dantrolene
Bicarb 1-2 meq/kg IV then check ABG
Start cooling measures (iced IV NS (not LR) 15cc/kg every 10min x 3 and if necessary do cold body cavity lavage, cooling blankets, ice bags

Question 25

Why wouldn’t you use LR during MH?

Answer 25

Due to the extra Calcium and Potassium

Question 26

What is the dose for continued Dantrolene after initial dose and how long will you continue that dose?

Answer 26

Dantrolene 1mg/kg IV q 6hrs for 72hrs

Question 27

Should you use Calcium Channel blockers for tachycardia during MH?

Answer 27

no because it can cause life-threatening hyperkalemia and myocardial depression

Question 28

What is the mechanism of action for Dantrolene?

Answer 28

Interferes with muscle contraction by inhibiting Calcium release from the sarcoplasmic reticulum

Question 29

Does Dantrolene work intracellularly or extracellularly?

Answer 29

works by intracellular dissociation of excitation-contraction coupling

Question 30

Is Propofol a safe drug to use during a surgery on someone with a known history of MH?

Answer 30

Yes, along with other IV drugs like benzos, barbs, etomidate, narcs, local anesthetics, NONDEPOLARIZING MUSCLE RELAXANTS, N2O, Ketamine,

Question 31

What is the GOLD STANDARD for diagnosing MH presurgery?

Answer 31

muscle biopsy with halthane-caffeine contracture test

Question 32

What is King-Denborough syndrome?

Answer 32

myopathy, short stature, cryptorchidism, pectus carinatum, lumbar lordosis, kyphosis, unsusual facial characteristics

Question 33

If someone has a prior uneventful general anesthetic, does that rule them out for having any other issues with MH in the future?

Answer 33

No, can undergo multiple uneventful episodes of anesthesia before developing MH

Question 34

Does Trismus (masseter spasm) alone after succinylcholine mean MH?

Answer 34

no, can happen 1% of time using succs

Question 35

In boys under 9yrs who develop sudden cardiac arrest after induction with succs and absence of hypoxia, should be treated for hyperkalemia or MH?

Answer 35

Hyperkalemia first since this is the most likely cause.

Question 36

How quickly do people usually develop MH after exposure to trigger substances?

Answer 36

Usually within 1 hr

Question 37

What is considered a “full” supply of Dantrolene to have on hand?

Answer 37

36 vials

Question 38

Does postoperative fever alone indicate MH?

Answer 38

Very unlikely without other signs/symptoms like increasing CO2, hypoxia, etc.