What is the most sensitive predictor for successful extubation?
D. Minute ventilation <10 L/min
The rapid shallow breathing index (RSBI) is the ratio of the respiratory frequency (f) and the tidal volume (VT). An RSBI <105 has been shown to be the most sensitive criteria for weaning patient to extubation.
A 68 year old female is postoperative day 3 status post a pancreaticoduodenectomy. Her post-extubation arterial blood gas shows: pH 7.58, pCO2 30, HCO3 26, O2Sat 94%, and BE 2.2. Based solely on this ABG, what is her underlying acid-base disturbance?
B. Compensated metabolic alkalosis
First, look at the pH; in this case it is alkalotic. You must now distinguish if this is respiratory, mixed, or metabolic. So pay attention to the pCO2 and the HCO3 and note that the HCO3 is normal but the pCO2 is low. The characteristic of respiratory alkalosis is increase in pH with decrease in pCO2. In the acute setting, note that HCO3 typically decreases by 2 mEq/L for every 10 mm Hg drop in pCO2. In chronic respiratory alkalosis, HCO3 typically increases by 4 mEq/L of HCO3 for every 10 mm Hg drop in pCO2.
Which is not indicative of ARDS?
C. Wedge pressure <18 mm Hg
The distinction between ALI and ARDS is the degree of hypoxemia defined by the P/F ratio. In ALI the ratio is less than 300 mm Hg and for ARDS it is 200 mm Hg or less.
Which of the following ventilation modes is more likely to cause increased auto-PEEP?
A. Pressure support ventilation
B. Airway pressure release ventilation
C. Assist control ventilation
D. Pressure-controlled inverse ratio ventilation
E. Continuous positive pressure ventilation
Normal respiration typically has an inspiration to expiration ratio of 1:2. This means that inverse ratio makes inspiration time longer than expiration time. High inverse ratios do not allow adequate expiration time and patients usually stack their breaths. Thus, every inspiration occurs before expiration is complete resulting in auto-PEEP.
A normotensive bleeding patient is mildly anxious with a HR of 110 and an RR of 25. What class of hemorrhagic shock is she in?
In Class I hemorrhagic shock, the patient has normal mental status. Class II is defined as 750- to 1500-mL blood loss; 15% to 30% blood loss; HR >100 bpm; normal blood pressure; decreased pulse pressure; RR 20 to 30 breaths/min; urinary output 20 to 30 mL/h and mildly anxious.
Approximately 5 hours after ruptured AAA repair, you are called to see a patient with only 15 cc of urine for the past 2 hours. Intraoperatively, she received 9 L of crystalloid and 4 units of pRBC. At the bedside, you are also informed that his peak airway pressure on the ventilator is 42 mm Hg. His BP is 90/52, HR 115 bpm. What is an appropriate next step?
A. Diuresis with furosemide
C. Check bladder pressure
The oliguria, low CVP, and hypotension could be suggestive of underresuscitation. However, the very high peak airway pressure in conjunction with the other findings plus the fact he had very large fluid resuscitation in the operating room should increase the suspicion for abdominal compartment syndrome. Measuring the bladder pressure would be the next best decision since the other choices would not be beneficial in this scenario.
Which of the following is most likely suggestive of hypovolemic shock?
Choice A is more descriptive of distributive shock with high CI and lower SVR. Overall, B would most likely represent cardiogenic shock with the lower than normal CI and high wedge pressure. In hypovolemic shock preload (CVP) is decreased, leading to decreased PCWP and CO.
The formula for oxygen extraction ratio is:
The oxygen extraction ratio (O2ER) is the ratio of oxygen consumed to that delivered (VO2/DO2). It represents the amount of oxygen delivered via the circulation that is taken up by the tissues. Normal O2ER is 0.2 to 0.3, indicating that only 20% to 30% of the delivered oxygen is utilized.
Use the equation below to calculate the respiratory quotient:
C6H12O6 + 6O2 → 6CO2 + 6H2O
The respiratory quotient is the ratio of the volume of carbon dioxide produced to the volume of oxygen consumed per unit of time by the body. The equation above illustrates the utilization of glucose. Six molecules of carbon dioxide are produced for the 6 molecules of oxygen used up.