Term
| Which is most likely to contribute to excess CO2 production: carbohydrates, fat, protein, or total calories? |
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Definition
| Total calories are responsible for excess production of CO2 rather than particular substrates |
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Term
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Definition
- ARDS is a disorder characterized by widespread inflammation in the lungs.
- It is not a particular disease, but rather a clinical phenotype with a variety of causes.
- ARDS results in impaired gas exchange at the level of the microscopic alveoli
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Term
| What are the diagnostic criteria for ARDS and what are their significance? |
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Definition
The diagnostic criteria are:
- Acute onset of diffuse bilateral pulmonary infitrates by chest radiograph
- Partial pressure of oxygen in blood/fraction of inspired oxygen <300 for ALI and <200 for ARDS
- Pulmonary artery wedge pressure <18 mmHg or no clinical evidence of fluid overload
The partial pressure is a measure of the amount of oxygen in the blood per amount of oxygen delivered to the patient. Smaller amounts indicate hypoxemia.
Normal pulmonary artery wedge pressure establishes that the infiltrates are inflammatory in nature and not the result of pulmonary edema. |
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Term
| What categories of clinical disorder give rise to ALI/ARDS? |
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Definition
- Disorders associated with direct injury to the lung (aspiration, pneumonia, pulmonary contusion, fat emboli, smoke or toxic gas inhalation)
- Those that cause indirect injury to the lung by inciting a systemic inflammatory response (sepsis, traumatic shock, pancreatitis, cardiopulmonary bypass, blood transfusion)
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Term
| What are the advantages of tracheostomy in prolonged mechanical ventilation? |
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Definition
- Increased level of comfort
- Better oral care
- Reduced rates of pneumonia
- Decreased dead space ventilation
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Term
| Why is ventilator support difficult with COPD and other obstructive disorders? |
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Definition
| Decline in respiratory muscle function cannot compensate for progressive increase in inspiratory volumes and overdistention that is classic with COPD, leading to increasing ventilator dependence |
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Term
| What nutritional state do patients with acute respiratory failure typically exhibit? |
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Definition
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Term
| What medication-related factors should be considered in patients with pulmonary disease? |
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Definition
Patients with severe ALI/ARDS are often heavily sedated or even paralyzed. This can mask signs of EN intolerance, which should be closely monitored.
Patients with acute or chronic pulmonary failure often receive inhaled or oral steroids, which should be considered in terms of vitamin supplementation and preventing hyperglycemia. |
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Term
| How do low FFMI and BMI correlate with long-term survival in patietns with long-term supplemental oxygen or PMV? |
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Definition
| Low FFMI (but not BMI) has been shown to be an independent predictor of long-term survival in patients requiring long-term supplemental oxygen or PMV. |
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Term
| What is the ideal tool for measuring calorie expenditure in pulmonary patients? |
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Definition
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Term
| When should indirect calorimetry NOT be used in ventilated patients? |
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Definition
Indirect calorimetry should NOT be used in ventilated patients with:
- An elevated fraction of inspired oxygen
- Positive end-expiratory pressure (PEEP)
- When an air leak in the circuit is present
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Term
| What are the dangers of underfeeding ventilated patients? |
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Definition
| For those on the ventilator, a cumulative caloric debt of 10k calories leads to longer ICU stay and prolonged ventilator weaning |
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Term
| What is permissive hypercapnea? |
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Definition
- In ventilated patients tidal volumes are limited to prevent further inflammation and baro-trauma
- Due to limited tidal volume, CO2 is allowed to rise above normal level as long as pH is maintained above 7.2
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Term
| What conditions is permissive hypercapnea used for? |
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Definition
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Term
| What is the relevance of permissive hypercapnea to nutrition? |
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Definition
| Because the CO2 release mechanism (tidal volume) is limited, it is important to regulate the amount of CO2 produced by substrate metabolism |
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Term
| Can patients with prolonged mechanical ventilator support suffer from overfeeding? |
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Definition
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Term
| Which is more likely to result in overfeeding in ventilated patients: PN or EN? Why? |
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Definition
| PN is more likely to result in overfeeding in ventilated patients, likely due to absorption, initiation, and tolerance limitations of EN |
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Term
| What should be done when overfeeding is suspected? |
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Definition
- The patient should be measured with indirect calorimetry if possible.
- Total macronutrient (energy) provision should be reduced
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Term
| How should lipids be provided for pulmonary failure patients on PN? |
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Definition
| Soy-based lipids should be witheld during the first week |
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Term
| Should glutamine be provided to pulmonary failure patients? |
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Definition
| Sometimes. IV glutamine should be provided to pulmonary failure PN patients and enteral glutamine should be provided to patients with burns, trauma, or mixed critical care populations. |
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Term
| Should arginine be used patients with pulmonary failure? |
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Definition
| Arginine should be used with caution in pulmonary failure patients with sepsis |
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Term
| Are high-fat, low-carb formulas recommended for patients with pulmonary failure? Why? |
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Definition
| No, because total energy intake (rather than a specific substrate) is what determines risk of overfeeding. |
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Term
| Should patients with ARDS receive supplements? If so, which type? |
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Definition
| Patients with ARDS should receive fish oil/borage oil/antioxidant supplement |
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Term
| What is the minimum caloric goal (as a percentage of total goal calories) for pulmonary failure patients? |
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Definition
| Pulmonary failure patients should receive a minimum of 50% of goal for immune-modulating diet efficacy |
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Term
| What level of protein should be provided to pulmonary failure patients? Why? |
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Definition
| 1.5-2 g/kg IBW to account for increased catabolism |
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Term
| What are effective measures for preventing ventilator-associated PNA? |
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Definition
- Elevation of the head of the bed
- Subglottic secretion draining
- Oral care with chlorhexidine
- Limiting time of mechanical ventilation
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Term
| What route should be used for EN in ventilated patients? |
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Definition
| A post-pyloric route (preferably jejunum) should be used for nutrient provision, with a nasogastric or orogastric tube used for stomach decompression |
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Term
| What is the prone position used for in pulmonary failure? What are the nutritional implications of this position? |
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Definition
| Patients with advanced respiratory failure and severe hypoxia are sometimes placed in the prone position. Gastric feeds are poorly tolerated in this position, but there is no difference in clinical pneumonia when comparing prone to supine positioning. There IS a higher rate of PNA when compared with the semi-recumbent position. |
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Term
| Is enteral feeding recommended for patients in the prone position? |
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Definition
| Safe enteral feeding can be achieved in the prone position, as long as the practitioner is vigilant to signs of intolerance or aspiration |
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Term
| Should patients at high risk of aspiration ever be excluded from EN provision? |
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Definition
| No, not unless there are confounding factors |
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