One Lung Ventilation & Malignant Hyperthermia - Quiz 9 Flashcards
When is One Lung Ventilation usually indicated?
Thoracic Surgery
VATS
Approach via Chest
Unilateral Lung Isolation
What type of Tubes do you use for One Lung Ventilation?
Double Lumen ETT
ETT w/ Bronch Blocker
Univent ETT
Endobronchial Intubation
ETT w/ Positive Pressure to One Side
What is the most common positioning for Thoracic Surgery
Lateral Decubitus
In lateral decubitus, which lung is the Dependent lung?
Lower Lung
In lateral decubitus, which lung is the Nondependent Lung?
Upper Lung
For thoracic surgery, how is the surgical field access povided?
Iatrogenic Pneumothorax of Upper Lung
What is the Fluid Management for Thoracic Surgery?
Restrict IVF d/t risk of lower lung edema
If the patient is awake and in lateral position, which lung is better Perfused & Ventilated?
Dependent Lung - Lower Lung
After induction, which lung does positive pressure ventilation and ventilation in general favor more?
Upper Lung
What increases the Compliance & Ventilation of the upper lung in lateral position?
Open Pneumothorax of Upper Lung
Lung Zone 1
PA > Pa > PV
Lung Zone 2
Pa > PA > PV
Lung Zone 3
Pa > PV > PA
What causes a large Right-to-Left Intrapulmonary Shunt during thoracic procedures?
Upper lung is not ventilating, but still perfusing
What does an Increased PA-a (Alveolar to arterial) O2 gradient lead to?
Hypoxemia
What decreases blood flow to the nonventilated upper lung and improves the Right-to-Left Shunt?
Hypoxic Pulmonary Vasoconstriction (HPV)
&
Surgical Compression of Upper Lung
What factors Inhibit Hypoxic Pulmonary Vasoconstriction (HPV)?
Very Low/High PAP or Mixed Venous PO2 (PVO2)
Hypocapnia
Vasodilators
Inhlation Agents
Pulmonary Infections
What factors decrease blood flow to lower lung and worsens Right-to-Left shunt?
More blood going to Upper Lung
Increased Airway Pressures
Hyperventilation
Low FiO2
Inadequate Expiratory Time
Vasoconstrictors have a greater effect on _______ vessels compared to ________ vessels
Vasoconstrictors have a greater effect on normoxic vessels compared to hypoxic vessels
CO2 elimination is not affected by one lung ventilation except for when?
Changes in Minute Ventilation
&
Preexisiting CO2 Retention
What should the Tidal Volumes be for One Lung Ventilation?
Same as Two Lung - 7-8cc/kg
How long can Ventilation be stopped for?
As long as O2 supplied is more than consumed
250-300cc/min
How fast does PCO2 increase during Apnea?
5 mmHg for first minute
then
3 mmHg for each minute after
What happens after 10-20 minutes of Apneic Oxygenation?
Progressive Respiratory Acidosis
How should you intubate to ensure proper ETT placement for one lung ventilation?
Use Fiberoptic Scope
What do you do for Hypoxia during One Lung Ventilation?
- 80-100% FIO2
- Check TV & ETT Placement
- Keep PaCO2 @ 40 mmHg
- Add 5cm CPAP to Upper Lung & 5cm PEEP to Lower Lung Slowly
- Clamp Upper PA
- Return to 2 Lung
What is the Criteria for Operability for Pneumonectomy
PreOp: FEV1 > 2L
PostOp: FEV1 > 800 mL
Split Lung PFTs if Failed
What are the FEV1/FVC and Max Breathing Capacity in high risk patients?
< 50% of Predicted
What is the RV/TLC for High Risk Patients?
> 50% of Predicted
What is the Max VO2 for High Risk Patients?
< 10 mL/kg/min
What is the DLco for High Risk Patients?
< 40% of Predicted
What are the Characteristics of Double Lumen ETTs?
- Left & Right Types
- Sizes: 35, 37, 39 (Women), 41 (Men)
- Longer, Blue Bronch Lumen
- Shorter Clear Tracheal Lumen
- Curved Tip
What are the possible complications of placing a Double lumen ETT?
Laryngitis
Hypoxemia d/t Bad Position
Bronch Trauma d/t overinflated cuff
Accidental Suturing
What is the most commonly used Double Lumen ETT?
Left Double Lumen ETT - easier to place
What triggers Malignant Hyperthermia?
Anesthetics Gases & Succinylcholine
What is the first and most sensitive sign of Malignant Hyperthermia?
Unexplained Tachycardia
What is the most specific sign of Malignant Hyperthermia?
Increasing EtCO2 @ 2-3X
What is the mortality rate of Malignant Hyperthermia?
10%
70% w/o Dantrolene
<5 % w/ Early Dantrolene
Once symptoms of Malignant Hyperthermia are controlled, what is the dosage to continue Dantrolene?
1 mg/kg IV q6h x 72 hrs
If a patient is on Dantrolene, what would cause life-threatening Hyperkalemia & Cardiac Depression?
Calcium Channel Blockers
How does Dantrolene work?
Directly on Ryanodine Receptor preventing Calcium Release from the SR.
What are late signs of Malignant Hyperthermia?
Organ Failure
DIC / Coagulopathy
Rhabdo
Edema / Swelling
Death
A patient’s tendency for fever, heat stroke, strabismus, exercise myalgia, cramping, and history of muscle diseases may indicate what?
Risk for Malignant Hyperthermia
What is the Gold Standard PreOp test for MH?
Halothane-Caffeine Contracture Test
What is King-Denborough Syndrome?
Combination of musculoskeletal diseases and deformities that makes them a risk for Malignant Hyperthermia
If the patient has had prior uneventful general anesthetic, does this rule out MH?
No!
Which age group is Malignant Hyperthermia more common in?
Children
When do symptoms of MH occur?
Usually within 1 Hour, but can be also be hours after exposure