In a kid with tracheobronchial obstruction due to a foreign body, what would you use for induction?
Inhaled induction with Sevoflurane. This will keep the patient spontaneously breathing. IF you place the kid on mechanical ventilation, you risk pushing the object further into the lungs
What treatment modality can you use to decrease splinting in patients who have just received thoracic surgery or upper abdominal surgery?
Thoracic epidural. This is > incentive spirometry because IS is limited by pain
What is the difference between PaO2 and SaO2?
PaO2: This is the partial pressure of O2 in the blood
SaO2: This is the amount of hemoglobin that is bound to oxygen. This is a calculated number and it assumes that all hemoglobin is normal hemoglobin.
What might a capnogram look like if a patient has COPD and had a single lung transplant?
It will have a sharp initial downward spike and then will rise prior to inhalation
What factors affect the DLCO?
- membrane thickness and integrity
- Cardiac output
- Hgb
- Clots (aka PE) decrease the amount of CO that is able to be absorbed by the lung
What is the physiologic dead space equation?
- Vd/Vt = (PaCO2-PeCO2)/PaO2
What will an INTRAthoracic obstruction look like on flow volume loops? What will EXTRAthoracic obstruction look like? Fixed obstruction?
- INTRAthoracic obstruction will have blunting of the EXPIRATION phase
- EXTRAthoracic obstruction will have a blunting of the INSPIRATION phase
- Both will be blunted
What muscles are used during forced exhalation?
Abdominal wall muscles, including the internal and external oblique muscles as well as the transverses abdomens
When storing RBC for transfusion, what change occurs in the Oxygen dissociation curve, and why?
- The curve shifts to the L
2. This is due to a decrease in 2,3 DPG levels
Describe some anesthetic considerations in a patient with CF?
- Avoid anticholinergics, as these will dry out their secretions and make them more thick
- Higher FiO2 to reduce PVR
- Increased airway reactivity
- Increased risk for spontaneous PTX
- Decreased Vitamin K and therefore bleeding risk is increased
Describe the metabolic compensation seen in chronic vs. acute respiratory acidosis.
- Acute respiratory acidosis leads to a 2 mm/mol increase for every 10 of CO2 over 40
- Chronic respiratory acidosis means that there is a 4 mol increase for every 10 of CO2 above 40
Describe diffusion hypoxia, aka the “Fink” effect.
the Fink effect is caused by the use of high dose N20 at 70%. Because N20 comes off so quickly, it causes a displacement of CO2 and O2 into the alveoli, which then leads to transient hypoxia that lasts for 5-10 minutes. This can be offset by using supplemental O2 during the offset of the gas.
What are the causes of hypoxemia following placement of a patient in Trendelenburg? What effect does Trendeleburg have on CI?
- Reduction in chest wall compliance
- Reduction in TLC
- Endobronchial intubation (as the abdomen pushes up, the tube remains secure and can be pushed into the R bronchus. Suspect this if a patient desaturates immediately following placement in Trendelenburg)
- Increased pulmonary shunting
- Reduction in lung compliance
- It INCREASES CI due to a transient increase in venous return
How long should a patient stop smoking prior to surgery? What are the effects of smoking cessation and how long do each of them take?
- Patients should stop smoking 8 weeks prior
- You will see an increase in O2 delivery to tissues and decreased CO levels in one day
- 48-72 hours: Increase in secretions and RAD
- 2-4 weeks: Decrease in secretions and airway reactivity
- 4-6 weeks: improvement in immune system
- 8-12 weeks: better mucociliary movement and overall small airway function
What is the normal PaO2 to PAO2 ratio in spontaneously breathing patients? mechanically ventilated?
- Spontaneous: the arteriolar CO2 is always 2-5 higher than the end tidal CO2
- Mechanical: the arteriolar CO2 is always 5-10 higher than the end tidal CO2
What are the anesthetic implications of a patient with RA? What do we need to NOT worry about?
- C2-C3 subluxation, may need to do awake fiberoptic depending on degree of subluxation
- Issues opening their mouth d/t involvement of the TMJ
- Difficulty placing the ETT due to involvement of the bones in the glottis
- inability to use NSAIDs, due to renal involvement from their chronic NSAID use
We DO NOT need to worry about bronchospastic disease, unless they have a concurring disease on top of their RA
How do patients with mild, moderate, and severe pulmonary obstructive disease present with use of bronchodilators on PFTs?
- Moderate disease will show the most improvement with bronchodilators
- Mild and severe disease will show the least improvement
What can you use transesophageal monitoring for?
You can use transesophageal monitoring to determine pleural pressures when chest wall pressure may elevated
What effect does general anesthesia have on lung volumes?
- Decreased FRC due to decrease in muscle tone, this leads to atelectasis
- You would not see this with Ketamine because it preserves muscle function
Do you see atelectasis with aging?
NO. If it is a healthy adult, you see an increase in closing capacity above the FRC, which leads to air trapping, NOT atelectasis
What are the physiologic effects of CPAP?
- CPAP opens the airways, stents open the alveoli, which then leads to increase in FRC
- It can also decrease depletion of surfactant, which also increases FRC
- Increased I and E time with increased TV: so you see a decrease in RR and an increase in TV
- Improved oxygenation and less of a R to L shunt
- Improved PVR due to improved oxygenation
- Decreased CO due to decreased VR
Describe ventilation and perfusion of the lungs at the apices vs. the base.
- Apical has lower Ventilation and perfusion than the bases, BUT the ventilation in the apex itself is greater than perfusion
- In the base of the lungs, the ventilation and perfusion are greater than in the apices, BUT the perfusion in the base of the lungs is greater than the ventilation
What happens to trans pulmonary pressures in the apex of the lungs vs. the base?
Transpulmonary pressures are highest in the apex, and this is because the pleural pressure is more negative at the top
Where is resistance highest in the airway? Describe why this is.
- It is highest in the large bronchi.
- This is because as the bronchi branch into bronchioles and then into alveoli, the overall surface area increases. In using the equation of Resistance = 1/r^4, the “r” is actually the cross sectional area. This being said, as the cross sectional area increases, the resistance decreases.
- Additionally, The bronchi are irregular, and branched, making turbulent flow greater at the bronchi than in the alveoli (which are more regularly shaped)
