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Respiratory
Medical-Acute Care
Question | Answer |
---|---|
what does oxygen delivery (DO2)depend on in order to give tissues oxygen to survive? | adequate vintilation, gas exchange and circulatory distribution |
what are the two main categories resulting from tissue hypoxia ? | arterial hypoxaemia and failure of the oxygen-haemoglobin transport system without arterial hypoxaemia |
what are six pathophysiological mechanisms that cause arterial hypoxaemia? | Low inspired oxygen partial pressure (PO2), hypoventiliation, shunt, ventilation/perfusion mismatch (V/Q), imparied diffusion, venous saturation |
what are clinical featrues of tissue hypoxia? | non specific factors that include AMS, syspnoea, hyperventilation, arrhythmias and hypotension. |
what do you call the rightward shift of the dissociation curve that ensures adequate tissue DO2 in chronic hypoxia? | compensatory mechanisms |
what defines the oxygen hemoglobin relationship? | Arterial Oxygen Tension and hemoglobin saturation are inversely related and modified by Temp, PH, and 2,3 diphospoglycerate |
what is the difference b/w arterial tension and arterial saturation? | PaO2 is the tension driving oxygen into tissues and arterial So2 reflects the level of oxygen carriage by haemoglobin molecules |
when PaO2 and SaO2 are used to adjust oxygen therapy, what factor can trick the criteria for adjustment? | Low CO, anemia, or failure of oxygen utilization. |
For low CO, anemia, or failure of O2 utilization what is the best indicator of inadequate tissue DO2?` | Mixed venous oxygen saturation (SvO2) <55-60% (normally >70%) reflects inadequate DO2. |
what condition is defined as an arterial oxygen <8 kPa or arterial carbon dioxide (PaCO2) >6kPa | acute, chronic, or acute on chronic Respiratory failure (RF) due to inadequate gas exchange. |
what are the two types of respiratory failure? | Type 1: due to failure to oxygenate Type 2: due to failure to ventilate |
what are seven indications for intubation? | RR>35, PaO2 < 8kPa on > 50% FiO2, PaCO2 >7.5 kPa, PH < 7.25, decreased conscious level (GCS <8), inadequate secretion clearance, exhaustion and failure to improve within 1-4 hours with NIV |
what should be prescribed on the drug chart, signed for by the doctor, and documentedby the nursing staff at each drug round? | dose, delivery method, duration, target saturation, potential benefits, side effects and indications for drug therapy. |
what is therapeutic aim of oxygen therapy guided by? | Hyper Capnic Respiratory Failure, low risk in normal pts, high risk in COPD, pneumonia, neuromuscular disease, chest wall disorder, morbid obesity, cystic fibrosis, exertional dyspnea w/o other cause of breathlessness |
in pts at risk for HCRF what results from a higher SaO2 (>88%-92%)? | hypoventilation, hypercapnia and respiratory acidosis in pts dependent on hypoxaemic respiratory drive. |
on low dose controlled supplemental oxygen, what is the exception to the therapeutic adjustment? | if PaCO2 is normal , SaO2 is adjusted to 92%-98% and ABG checked on the hour, unless pt is prior HCRF. |
what are risks associated with high dose oxygen therapy? | CO2 retention, Rebound hypoxaemia, Absorption collapse, Pulmonary oxygen toxicity, Fire, Paul-Bert Effect (hyperbarric O2 can cause cerebral vasoconstriction and epileptic effect) |
when is oxygen therapy safely discontinued? | when the pt is clinically stable on low dose oxygen (1-2 LPM), and SaO2 is within the desired range on two consecutive occasions. Monitor SaO2 for 5 minutes after stoping oxygen and recheck at 1 hour. |
what are other techniques to improve oxygenation? | Blood Transfusion for anaemia, bronchoscopy and mucolytics for secretion retention, alveolar edema in ARDS is reduced by fluid restriction, V/Q mismatch and shunt is reduced by alveolar recruit, vent support corrects hypoventilation/hypercapnia |
what are two benefits to positive pressure Non invasive ventilation? | PPNIV avoids pulmonary infection, reduces pressure damage and allow time to decide if MV is appropriate |
what are two limitations to PPNIV? | It may lead to gastric dilation which requires suction from an NG tube, impedes sputum clearance, and may cause ulceration over nasal bridge. |
what are some factors associated with success of an NIV? | Conscious level of awareness, improvement of PH PaCO2, and RR within 1 hr of NIV. |
what are factors associated with failure? | PH , 7.25, copious resp secretions, High APACHE score |
What is an APACHE score? | The Apache-II Score provides an estimate of ICU mortality based on a number of laboratory values and patient signs taking both acute and chronic disease into account. (mdcalc.com) |
If a PaCO2 remains elevated in a pt with NIV what should you do? | increase IPAP or decrease EPAP |