Pulmonary Flashcards
Central control: brain stem
Senses pH, decreased pH > ventilation is stimulated > increased RR
Peripheral control: PaO2 sensors in aortic arch
Senses PaO2 > decrease in PaO2 (hypoxemia) > ventilation is stimulated > increased RR
How to know if ventilating normally?
PaCO2! NOT PaO2
Minute ventilation
Tidal volume x RR
Normal is approx. 4L/minute
Increased minute vent = increased WORK OF BREATHING
Primary muscle of ventilation
Diaphragm!
Anatomic dead space
Doesn’t participate in gas exchange
Dead space is approx. 2ml/kg of Vt
Alveolar dead space
Pathologic, non-perfused alveoli (PE)
Physiologic dead space
Anatomic + alveolar dead space
Perfusion def
Movement of blood past alveoli
Normal ventilation/perfusion ratio
4L ventilation/min
5L perfusion/min
Ideal lung unit = 0.8 VQ ratio
Can be decreased by PE or low CO
How to position R lung PNA
GOOD LUNG DOWN
Treatment of VQ mismatch
Give O2, treat cause
Lung shunt such as ARDS
An extreme VQ mismatch, even on 100% O2 will not correct hypoxemia
Treatment: give 100% O2, PEEP
Shunt def
Movement of blood from R side of heart to L without oxygenation
Normal physiologic shunt
Thebesian veins of the heart empty into L atrium
Anatomic shunt
VSD or ASD
Pathologic shunt
ARDS! Blood goes through without being oxygenated resulting in refractory hypoxemia
PEEP
Prevents expiratory pressure from returning to zero, by keeping exp. pressure positive it
- decreases surface tension of alveoli
- increases alveolar recruitment
- increases driving pressure, extends time of gas transfer and allows decrease in FiO2
Left shift of oxyhemo dissociation curve
Alkalosis
Low PaCO2
Hypothermia
Low 2,3-DPG
SaO2 high but O2 stuck to hgb > BAD
Right shift of oxyhemo dissociation curve
Acidosis (high H+)
High PaCO2
Fever
High 2,3-DPG
Good for tissues, SaO2 low but O2 easily released
What is 2,3-DPG?
Organic phosphate in RBCs that alters affinity of hgb for oxygen
Decreased 2,3-DPG
Multiple blood transfusions
Hypophosphatemia
Hypothyroidism
Less O2 available to tissues
Increased 2,3-DPG
Chronic hypoxemia
Anemia
Hyperthyroidism
More O2 available to tissues
Carboxyhemoglobin levels & symptoms
0-5 is normal <15% often in smokers 15-40 headache, some confusion 40-60 loss of consciousness, Cheyne-Stokes 50-70 mortality >50
Treatment of CO poisoning
100% FiO2 until symptoms resolve and level is <10%
Hyperbaric chamber
Static compliance def
Measurement of elastic properties of lung
TV/plateau pressure
Increase is PP will decrease compliance
Dynamic compliance def
Measurement of elastic properties of airways
TV/peak inspiratory pressure
Increase in PIP will decrease compliance
Status asthmaticus
Static compliance (lungs) normal Dynamic compliance would be low
ARDS
Static compliance would be low
Dynamic would also be low
Anion gap
Normal 5-15
Helpful in determining cause and response to treatment of metabolic acidosis
Problems with increased anion gap
Ketoacidosis Uremia Salicylate intoxication Methanol Alcoholic ketosis Unmeasured osmoles Lactic acidosis
Problems with normal anion gap
Saline infusion TPN Diarrhea Ammonium chloride Acute renal failure
Acute resp failure type 1: hypoxemic
PNA, ARDS, atelectasis, pulm edema, PE, interstitial fibrosis, asthma
Acute resp failure type 2: hypercapneic
CNS depression due to drugs, increased ICP, COPD, flail chest, ALS, Guillian Barre, MS, spinal injury
Acute resp failure type 3: combo
ARDS, asthma, COPD
S/S of hypoxemic resp failure
Tachynpea, accessory muscle use, tachycardia at first then brady, cyanosis, anxiety, agitation
S/S of hypercapneic resp failure
Shallow breathing, bradypnea, progressive decreased LOCA
Treatment of resp failure
Maintain airway and improve ventilation, optimize oxygenation, circulation and CO, identity etiology
CPAP
Indicated for patients with hypoxemic resp failure who have increased work of breathing (cardiogenic pulm edema)
BiPAP
Indicated for patients with hypoxemic or hypercapneic resp failure
Advantages of noninvasive ventilation
Buys time, reduces work of breathing, decreases preload and afterload, improves oxygenation, prevents intubation
Contraindications for NIV
Unstable or life threatening arrhythmia, secretions, high risk aspiration, impaired mentation, pneumothorax, life threatening refractory hypoxemia
Signs of acute exacerbation of COPD
Worsening dyspnea, increase sputum volume and thickness, hypercapnia and hypoxemia
Management of COPD exacerbation
Titration FiO2 to PaO2 >60 without overcorrecting
Bronchodilator therapy - short acting beta agonist and anticholenergic
Steroids
Antibiotics for PNA
NIV
Status asthmaticus def
Airway hyper-reactivity that produces severe airway narrowing that is refractory to aggressive bronchodilator therapy
S/S of status asthmaticus
Dyspnea, tachypnea, cough, accessory muscle use, wheezing > decreased breath sounds, VQ mismatch, tachycardia, pulsus paradoxus, decreased LOC, elevated WBC, hx of intubations
Management of status asthmaticus
Measure presenting peak flow rate
50-70 admit, <50 ICU
Bronchodilator, anticholenergic, steroids, pulse ox, hydration, avoid secretions, intubation (resp acidosis, severe hypoxemia, silent chest, change in LOC)
Vent management of status asthmaticus
Use low rate to increase exhalation time, low TV to prevent auto PEEP, increase I/E ratio
Types of PE
Venous - DVT
Fat - long bone, pelvis
Air - surgery, IVs
S/S of PE
Dyspnea, tachycardia, CP, anxiety, cough, petechaie (fat), low grade fever, resp alkalosis
Severe: hypoxemia, hypotension, EKG changes, PEA
Treatment of PE
Adequate oxygenation, fluids, anticoagulant, fibrinolytic therapy, maintain CO
Pulm HTN def
MEAN pulm artery pressure greater than 25 at rest and PAOP less than 16 at rest with secondary R HF
S/S of pulm HTN
Exertional dyspnea, lethargy, fatigue, progression to RV failure, CP and syncope, abdominal pain, ortners syndrome, systolic murmur, RV hypertrophy, JVD distention, ascites, pleural effusion
Tx of pulm HTN
Diuretics, oxygen, anticoagulant, digoxin, exercise training
Lastly transplant
S/S of PNA
Chills, fever, tachycardia, confusion, productive cough, dehydration
Tx of PNA
Optimize ventilation and oxygenation, positioning GOOD LUNG DOWN, NIV or intubation, bronch, mobilize, identify organism, antibiotics
Etiology of aspiration
AMS, drug use, depressed cough/gag, feeding tubes, positioning, artificial airway, gastric distention, hx of dysphagia, increased secretions
S/S of aspiration
Resp distress, tachycardia, hypoxemia, crackles, secretions, hypotension
