Respiratory Failure. 1.Abstracts. Respiratory failure, whether acute or chronic, is a frequently faced problem and a major cause of death in our country. For example, mortality from COPD, which ends in death from respiratory failure, continues to increase.
Usually, the volume of ventilation is 4 liters/min. The volume of lung blood is 5 liters/min. So the ratios is 0.8
For example, V/Q>0.8, including emphysema,pulmonary embolism.(无效腔）
V/Q<0.8, including atelectasis, severe COPD.（动静脉分流）
Diffusion abnormality mainly influence oxygen exchange.
Altered mental status Slurred speech
Bradycardia unbalance of acid-alkalose metabolic
Bronchodilators Route Dose
salbutamol MDI and spacer 400-600g q1-4h
Aerosol solution 2.5-7.5mg q1-4h
Ipratropium MDI and spacer 80-120g q4-6h
Theophylline IV 5.6mg/kg 0.3-0.6mg/kg/hr
The aim of mechanical ventilation is to improve hypoxemia and to prevent hypercapnia. When do you select mechanical ventilation? This is a question we always meet in our clinical work.
1.progressive elevation in PaCO2>70-80mmHg
2.severe hypoxemia, after oxygen therapy, PaO2<40mmHg
3.respiratory rates>35 per minute or severe breathlessness
4.severe metabolic acidosis or pulmonary encephalopathy
face mask or nasal noninvasive intermittent positive pressure ventilation are delivered to augment alveolar ventilation and reducing the work of breathing.
If hypoventilation can not be effectively reverses by noninvasive methods, intubation must be adopted. When artificial ventilation is required for more than 2 weeks, a tracheotomy is often required.
Tracheotomy carries some risk of bleeding, pneumothorax, and local infection and incidence of aspiration.
According to sputum culture, we can select sensitive antibiotics
Because of multibacteria infection, it needs several kind of antibiotics. For example, we may combine second or third generation cephalosporin to aminoglycoside or fluoroguinolone.
nasal prongs 1-3L/min to chronic respiratory failure
venti mask 1-3L/min
For type 1 respiratory failure, we can elevate the percentage of oxygen to maintain the PaO2.
We can use higher inspirated fration of oxygen in type 1 respiratory failure oxygen therapy. But in type 2 respiratory failure we must select lower inspirated fration of oxygen .
the acid-base index.
the index of respiratory
is the most important .
BE13.9 HCO3- 41mmol/L
BE-7; HCO3- 20mmol/L
BE5.1; HCO3- 33.8mmol/L
Because of hypoxemia, hypercapnia and by using corticosteroids, gastrointestinal bleeding always be happened.
The treatment mathod include correct hypoxemia and hypercapnia, use of H2-blocker and some block bleeding drugs.
First stage- sometimes normal, sometimes small patches may be exist
Second stage- diffused small or large patches, usually in lower lung field
Third stage- pulmonary infiltrate involved all potions of the lung, called ‘white lung’
Severe arterial hypoxemia is a characteristic clinical sign of ARDS. In genaral, the lowest inspired fration of oxygen(FiO2) should be used to give the desired result. There are multiple means for delivering O2, including soft nasal prongs, simple face masks. But in the condition of ARDS, these methods are not effective. Mechanical ventilatory support should be used early to improve hypoxemia.
PEEP means positive end-expiratory pressure. It helps maintain alveolar potency in the presence of destabilizing factors and therefore reverses hypoxemia and atelectasis by improving V/Q matching.
PEEP level between 5-15cmH2O are safe and effective.
Endotracheal intubation is usually adopted during mechanical ventilation. Intubation should be by the orotracheal or nasotracheal route is highly controversial.
Continuous positive airway pressure, CPAP/positive end-expiratory pressure, PEEP
A、呼吸性酸中毒代偿 B、呼吸性酸中毒失代偿 C、呼吸性酸中毒+代谢性碱中毒 D、呼吸性酸中毒+代谢性酸中毒 E、代谢性碱中毒
A、通气/血流比例失调 B、弥散功能障碍 C、肺泡通气量不足 D、氧耗量增加 E、肺内动静脉分流增加
A、肺组织弹力减退 B、通气与血流比例失调 C、肺动脉分流异常 D、弥散功能
A、血压下降，脉搏减慢 B、血压上升，脉搏增快 C、血压不变，脉搏减慢 D、血压上升，脉搏减慢 E、血压下降、脉搏增快
D. PaO2>50mmHg, PaCO2<35mmHg