Respiratory Flashcards
Do you want the “good” lung down or up when it comes to positioning? In R lung PNA? What happens during PRONE positioning?
Good lung DOWN b/c pulmonary blood will cover perfuse the good lung. For RIGHT PNA, LEFT lung should be down, if RIGHT lung down then pt will become hypoxemic.
Perfusion of under-perfused anterior chest aveoli explains the improved oxygenation seen during PRONE positioning for severe hypoxemia.
Normal vs Abnormal VQ ratio
Treatment?
Normal: 0.8 - 4L ventilation per min (V) / 5L perfusion per min (Q)
Abnormal: When there is a problem with ventilation or perfusion - V/Q mismatch. Develop hypoxemia on RA - HOWEVER providing oxygen will generally correct the hypoxemia until etiology can be determined and addressed.
What is a shunt?
Extreme V/Q mismatch; even providing 100% FiO2 will NOT correct they hypoxemia.
A shunt is movement of blood from the RIGHT side of the heart to the LEFT side of the heart without getting oxygenated; venous blood moves to the arterial side. Anatomic shunt: ventricular septal defect and atrial septal defect.
Oxyhemoglobin-Dissociation Curve
LEFT vs RIGHT shifts?
When SaO2 (arterial oxygenation) is less than 90%, the PaO2 (arterial oxygen) is less than 60 mmHg, when PaO2 is less than 60 mmHg, cells begin to have difficulty maintaining aerobic metabolism (without compensation, i.e. an increase in heart rate or oxygen delivery).
LEFT - results in higher SaO2 but the tissue do not get needed O2 readily
* Alkalosis (low H+)
* Low PaCO2
* Hypothermia
* Low 2,3 DPG
* Bad for tissues; SaO2 is high but O2 is stuck to Hgb
RIGHT - results in somewhat lower SaO2 but the tissues receive O2 more readily
* Acidosis (high H+)
* High PaCO2
* Fever
* High 2,3-DPG
* Good for tissues; SaO2 is low but O2 is easily released to the tissues
Static vs Dynamic compliance?
Does decrease in compliance increase or decrease the WOB?
Static - measurement of the elastic properties of the lung
* Tidal volume / plateau pressures (minus PEEP)
* Increase in plateau pressures will decrease compliance
Dynamic - measurement of elastic properites of the airway
* Tidal volume / peak inspiratory pressure (minus PEEP)
* Increase in in peak inspiratory pressure will decrease compliance
Normal for both is ~45-50 mL/H2O
Pt with airway problems (asthma) have decrease dynamic compliance but their static compliance remains normal
HOWEVER, pt with lung problems (PNA / ARDS) have decrease static compliance and dynamic compliance may also decrease as the lung pressure may transmit up to the airways
What is treatment of carbon monoxide poisoning?
100% FiO2 until symptoms resolve and carboxyhemoglobin level is <10%. Hyperbaric oxygen cahmber if available, generally within 30 minutes
COhb
* O-5 normal
* <15 OFten in smokers, truck divers
* 15-40 Headache, some confusion
* 40-60 Loss of consciousness, Cheyne-Stokes respiration
* 50-70 - mortality >50%
What is 2,3-Diphosphoglycerate?
Organic phosphate, found in RBCs, that has ability to alter the affinity for of hemoglobin for oxygen.
Decrease 2,3-DPG results in hemoglobin HOLDING on to O2 - DECREASE release of O2
* Multiple blood transfusions of banked blood
* Hypophosphatemia
* Hypothyroidism
Increase in 2,3-DPG results in hemoglobin RELEASING O2 - INCREASE release of O2
* Chornic hypoxemia (eg prolonged time spent at high altitudes or chronic HF)
* Anemia
* Hyperthyroidism
Anion Gap Value?
5-15 mEq/L - Difference between positive (K+ / Na+) and negative (Cl- HCO3-) anions. In most instance of metabolic acidosis, there is an INCREASE in anion gap.
Helpful in determining the cause of and/or response to treatment for metabolic acidosis. For instance, if a patient with DKA presents with an anion gap of 25 mEq/L, one would expect the anion gap to decrease gradually as the patient responds positively to treatment. Since electrolytes are frequently assessed, the acidosis can be monitored by monitoring the anion gap without getting frequent ABGs.
IPAP assists with ???
EPAP assists with ???
IPAP - ventilation
EPAP - oxygenation
Contraindications for NIV
- Hemodynamic instability or life-threatening arrhythmias
- Copious secretions
- High risk of aspiration
- Impaired mental status (unable to protect airway)
- Suspected pneumothorax
- Inability to cooperate
- Life threatening refractory hypoxemia (PaO2 < 60 with FiO2 1.0)
How does anticholinergics (Ipratropium aka Atrovent) work?
Ipratropium is an acetylcholine antagonist via blockade of muscarinic cholinergic receptors. Blocking cholinergic receptors decreases the production of cyclic guanosine monophosphate (cGMP). This decrease in the lung airways will lead to decreased contraction of the smooth muscles.
3 Ventilator Management for Status Asthamticus
- Use LOW rate to increase exhalation time
- Use LOW tidal volumes to prevent auto-PEEP
- Increase inspiration / expiration (I/E) ratio, often greater than 1:3-4, to allow time for optimal exhalation and to prevent auto-PEEP
Define pulmonary hypertension
Defined as a MEAN pulmonary artery pressure that is >25 mmHg at rest and a PAOP (PAD) <16 mmHg at rest with secondary RIGHT HF.
S/S
* Exertional dyspnea, lethargy, fatigue due to inability to increase cardiac output with activity
* RV failure - CP, syncope with exertion, peripheral edema
* Hepatic congestion –> anorexia / abd pain
* RV hypertrophy, JVD, hepatomegaly, ascites, and pleural effusions
Tx:
* Diuretics, oxygen, anticoagulants, digoxin and exercise training
* Dilators - CCB / phosphodiesterase-5 inhibitors sildenafil (Viagra), tadalafil (Cialis), or treprostinil (Remodulin)
Pnemonia
Acute inflammation of the lung parenchyma caused by bacteria / virus / fungi / parasite that can lead to alveolar consolidation.
Can be acquired via community acquired PNA (CAP), hospital acquired PNA (HAP) and ventilator associated pneumonia (VAP) aka ventilator associated event (VAE). HAP has greater mortality than CAP.
