AP EXAM 3 brainscape Flashcards
factors affecting post-op hypoxia
atelectasis (sit upright ,cough, breath deeeply)
pulmonary embolism and EtCO2
etCO2 decreases
ventilatory drive
relaxant? Opioid? Gas on board?
asthma, pathologic findings
airway remodelng, bronchoconstriction included, structural changes (hyperplasia, metaplasia, bronchial angiogenisis)
determinants of FRC
FRC is the volume in the lungs at the end of passive expiration, it is determined by opposing forces of the expanding chest wall and the elastic recoil of the lung, Normal FRC is 1.7-3.5 / FRC changes with body size, age, certain lung diseases, sex, diaphragmatiic muscle tone, posture, increased abdominal pressure
causes of obstructive sleep apnea
obesity
bronchiectasis, definition
destruction and widening of large airways that become easily collapsible, can begin in early childhood (similar to emphysema but in large aiways)
COPD, vent settings
controlled MV, large tidal volumes (10-15ml/kg) combine with a slow insp flow will minimize turbulent flow and help maintain optimal vent to perfusion matching, slow RR provide sufficent time for complete exhalation
calculating transmural CVP
Transmural CVP = CVP - Pleural pressure
chest tube maintenance
leave it clamped
asthma, induction agents
ketamine is a bronchodilator
asthma, exacerbating factors
- GERD (30-80% of asthma patients have GERD, frequently silent, 07% of asthmatics improve with antireflux therapy) GERD causes asthma/bronchospasm (aspiration of refluxed gastric contents, vagal response, esophageal muscosal receptors), Asthma causes GERD (autonomic dysregulation, bronchodilators, theophyline, steroids lower LES tone); 2. Aspirin, 5-20% of adult asthmatics have AIA
severe emphysema, lung lucency on CXR
hyperlucent bc lungs chronically inflated, flat diaphragm
severe emphysema, lung compliance
high lung compliance due to poor elastic recoil
V/Q relationships, upright lung
deadspace in upright lung, shunt in dependent lung
calculation, ideal alveolar oxygen tension
PAO2 = FiO2 x 713 - (40/0.8)
chronic restrictive disease, clinical findings
on room air, A-a gradient should be less than or equal to 4 + age/4
6 Intrathoracic vascular pressures
RA, CVP, PA systolic, PA diastolic, PA mean, LA pressure, RVEDP
Difference bt intra and extra thoracic pressures
extra would be atmospheric
Compliance=
change in volume/change in pressure
Which of the compliances can be measured on an anesthesia ventilator
Total (lung and thorax comp) TV/airway pressure
Normal lung-thorax compliances
total= 100, lung=200 thorax=200
post -op avg lung/thorax compliance
50ml/cmH2O
lungs and chest wall in series or parallel?
series
when during a spontaneus resp cycle do you measure hemodynamics
end-expiration, bc of steady state and more equilibrium
Transmural filling pressure?
measuring inside pressure and subtracting the outside pressure so you are getting the filling pressure
P(pl)=
P(pl) = P(aw) * C(L)/(C(L) + C(T))
Types of COPD
asthma, bronchitis, emphysema, bronchiectasis, bronchiolitis
Bronchitis
inflammation of large airways, causes: smoking, pollution, allergies, job hazards, symptoms: cough, mucus production, shortness of breath, wheezing, may be cyanotic
Tx of Bronchitis
minimize inflammation with short-term steroid therapy, bronchodilators using albuterol, hydration, antibiotics if there is a bacterial infection
Emphysema
One of the most common lung diseases, causes lung destruction of the terminal bronchioles to alveoli, slowly and irreversibly destroys the elastic fibers that hold open the small airways
Causes of emphysema
smoking most common, brochitis
Symptoms of emphysema
shortness of breath, impaired abilty to exhale
Pursing lips with emphysema
fxns as auto-peep
Treatment of emphysema
short acting bronchodilators (both B2 albuteraol and anticholinergic (atrovent)), long acting anticholinergic (spiriva), inhaled corticosteroids with long acting bronchodilator (advair), oral steroids (prednisone), antibiotics, oxygen in end stage, lung reduction surgery
define Bronchiolitis, and causes
swelling and build up in the bronchioles due to a viral infections, seen in children under 2, has a seasonal pattern usually fall and spring
symptoms of bronchiolitis
shortness of breath, cough, wheezing
TX of Bronchiolitis
antibiotics for recuurent infections, hydration, chest physical therapy, steroid therapy, bronchodilators
Causes of bronchiectasis
recurrent infections and inflammation, cystic fibrosis (50% of cases) TB
symptoms of bronchiectasis
shortness of breath, cyanosis, breath odor, chronic cough with foul sputum, finger clubbing
Tx of bronchiectasis
hydration, antibiotics if there is a secondary infection, antiviral drugs such as rebetol in severe cases, if hospitalized then humidified oxygen and IV fluids
6 risk factors for post-op pulmonary dysfuction
1) preexisting pulmonary disease 2) thoracic or upper ab surgery 3) smoking (risk of death 30x higher for heavy smokers) 4) obesity 5) age >60 years 6) prolonged general anestheisa ( >3 hrs)
obstructive pulmoary disease
total lung capacity is increase but there is a loss of expiratory reserve volume
COPD
_Elevated airway resistance and air trapping increase the work of breathing _Respiratory gas exchange is impaired because of ventilation/perfusion (V/Q) imbalance _The predominance of expiratory airflow resistance results in air trapping: residual volume and total lung capacity (TLC) increase.
COPD exacerbations
respiratory infections, allergens, pungent odors like perfumes, dust or mold
COPD, pre-op mgmt
_Patients with COPD should be optimally prepared prior to elective surgical procedures - Pt_s should be questioned about recent changes in dyspnea on exertion, sputum, and wheezing. -Smoking should be discontinued for at least 6-8 weeks before the operation to decrease secretions and to reduce pulmonary complications. Cigarette smoking increases mucus production and decreases clearance.
COPD treatments
acute exacerbation best treated with B2 adrenergic agents, other treatments include prednisone, ipratropium, leukotriene inhibitors, or theophylline
COPD pre-op assessment
smoke? Exercise tolerance? Last hospitalized for lung dz? Productive cough? Colored sputum? Medications? Listen. Pulmonary fxn studies. SpO2? On oxygen?
COPD, anesthetic mgmt
preox essential due to rapid desat, sevo or des preferred bc rapidly eliminated, controlled mechanical vent will optimize lung fxn, large tidal volumes (10-15cc/kg) with a slow insp flow will minimize turbulent flow and help maintain optimal ventilation to perfusion matching, slow RR (6-8) provide sufficient time for complete exhalation to occur
COPD post-op considerations
Patients with thoracic and upper abdominal surgery are at increased risk for postop complications like prolonged ventilatory support and pneumonia. Both these surgical locations prevent the patient from taking deep breaths and coughing to clear secretions. All COPD patients should be told of the possibility of having the endotracheal tube remain in place until their lungs are ready to have it removed as well as the possibility of postop ventilation. Pain is a major part of this problem and the use of epidural for pain management may allow the patient to take deeper breaths and cough. Oxygen administration is usually needed into the immediate postop period. A liter flow to maintain a Po2 of between 60-80 mmHg of a Spo2 of 90-95%.
Asthma
chronic inflammatory disorder (episodic, reversible bronchospasm, bronchial hyper-responsiveness to stimuli, airway remodeling, severity tends to increase with time) may not be a single clinical disorder; prevalance 6.7% in US
Asthma and death
50% of asthma deaths occur in patients over 65, underdiagnosed in the elderly
Asthma, preop mgmt
history (age of onset, triggers, hospitilzations, recent symptoms, medications) other history (recent uri, smoking, gerd, aspririn or NSAID sensitivity, response to prior anesthetics) BUT history can be misleading bc symptoms do not correlate with lung fxn, test peak expiratory flow rate (handheld meters, effort-dependent, 20% variability in baseline, diurnal variation)
Spirometry
can assess occult broncospasm (dyspnea, nocturnal cough, chest tightness); new diagnosis (can assess resolution of acute exacerbation, can predict response to bronchdilators); selective use is appropriate (quick and inexpensive, effort dependent, no advantage in predicting postop complications)
Asthma, volume loop
classic flow-volume loop shows reduced exp flow and vital capacity; concave shape of expiratory portion; FEV1 is the most reprodcible PFT parameter
Asthma, ABG
Hypercarbia or hypoxia indicative of severe disease, beware of CO2 normalization, abnormal postop in normal controls, chest x-ray is the only way to rule out confounding diagnoses
dead space lung
ventilation > perfusion
shunt lung
perfustion > ventilation
effects of prolonged shunt
hypoxic vasoconstriction kicks in; low BP decreased CO2 due to decreased CO
3 causes of A-a gradient abnormality
1) Right to left shunt 2) V/Q mismatch 3) diffusion abnormality
Right to left shunt
areas of the lung that are perfused by not ventilated; basically mixed venous blood getting back to arterial circulation without being oxygenated- therefore lowering overal PaO2
determining PaO2 not on room air
patients PaO2 should be around FiO2 x 5
ratio of meausred PaO2 to FiO2 should be
300-500; less than 250 indicates a clinically significant gas exchange problem
negative pressure in chest drainage systems
the maximum negative pressure (in cm H2O) generated by suction equals to the distance (in cm) the vent tube is below the water line (this can be adjusted)
life threatening thorax
air tension
how does air normally get into the chest
central line
structure of a chest tube
side holes to optimize drainage, radiodense line to help find on x-ray (line interrupted by most proximal hole in chest tube (the sentinal eye)
chest tube placement
over the rib to avoid vein, artery, nerve / aimed toward posterior portion of chest cavity since pts are supine, this helps with drainage / removal? When prob is fixed and chest no longer needs to be drained
chest tube 1 bottle drainage
2-4cm water at bottom, drainage enters bottle, if air- bubbles exit to atm, if fluid- fills fluid lecel
chest tube 2 bottle
bottle 1 is collection, bottle 2 keeps pt from introducing room air into chest cavity
surgeon places chest tube, when do you hook up tube?
before chest is closed, don_t want to cause a tension pneumo from PPV
chest tube with pneumonectomy
balance chest/mediastunum to avoid shifting
RLD
lung expansion is restriced but airway resistance and exp flow rates are normal; results in decreases lung volumes and decreased compliance
Resp compliance =
Lung + Pleura + Chest wall
RLD pathophysiology
Low lung volumes lead to atelectasis, V/Q mismatch and hypoxemia, decrease O2 diffusion, reduced FRC, reduced compliance, MV must be maintained by increasing RR
definition of RLD
spectrum of disorders characterized by a decrease in TLC
TLC meaured by
helium dilution or body plethysmography
Intrinsic RLD
pulmonary parenchymal or airspace disease (lung problem)
Extrinsic RLD
impaired lung expansion but normal lungs (extrapulmonary problem)
Acute Intrinsic examples
ARDS, aspiration pneumonitis
ARDS
acute inflammatory response to the lung resulting in noncardiogenic pulmonary edema (diagnostic criteria: acute onset, bilateral infiltrates on CXR PaO2/FiO2 < 18
ARDSNet vent protocol
avoid volutrauma and barotrauma (tidal volume 6cc/kg, PEEp at least 5, SpO2 88-95, PaO2 55-80 permissive hypercapnia
Chronic Intrinsic RLD
Interstitial lung diseases, sarcoidosis; insidious onset, chronic inflammation and progressive pulmonary fibrosis, disease my be confined to lungs or multiorgan (anesthetic technique doesn_t lead to exacerbations, work with what we’ve got)
Acute Extrinsic RLD
disorders of the pleura or mediastinum, pleural effusion, pneumothorax, pneumomediastinum
Chronic extrinsic RLD causes
obesity, pregnancy, ascites
Cobbs angle
> 100 resp failure
Tidal volume
about 500ml
Inspiratory Reserve Volume
3100ml
Expiratory Reserve Volume
about 1200
Residual Volume
about 1200
TLC
about 6000ml
VC
about 4800ml
Inspiratory Capacity
about 3600ml (TV+IRV)
FRC
about 2400ml (FRC =RV+ERV)
Normal FEV1/FVC ratio
80%
What to expect perioperatively with RLD
rapid desaturation, high airway pressues, sensitivity to respiratory depressants, and need for postop ventilatory support
