Her current ventilator settings are assist control AC respiratory rate RR of

Her current ventilator settings are assist control ac

This preview shows page 58 - 61 out of 105 pages.

Her current ventilator settings are assist control (AC), respiratory rate (RR) of 12/min, tidal volume (TV) of 500 ml, fraction of inspired oxygen (FiO2) is 50%, positive end expiratory pressures (PEEP) of 5 mm/Hg. The most appropriate intervention at this time is to A. decrease set respiratory rate B. increase the fraction of inspired oxygen C. increase PEEP D. increase tidal volume E. make no adjustments at this time Explanation: The correct answer is D. The key to this question is to recognize that this patient remains acidotic and hypercarbic despite intubation. In order to "blow off" more carbon dioxide and normalize the blood pH, you must increase minute ventilation (MV). If you remember that MV=TV X RR, you can
Image of page 58
quickly recognize that the two ways to decrease carbon dioxide is to increase the RR or increase the TV. Decreasing RR (choice A) will increase carbon dioxide because we are decreasing minute ventilation as described above. This will result in worsening acidosis. In addition, our set respiratory rate is lower than the patient's actual rate. If we decreased the respiratory rate, our patient would continue to breathe at a high rate and receive the same tidal volume (thereby not even changing the MV). Increasing FiO2 (choice B) will not be beneficial. First, the patient already has a paO2 of greater than 60 mm Hg. If you remember the hemoglobin binding curve, you should remember oxygen saturations remain above 90% for paO2>60 mm Hg. Therefore, our goal is to keep paO2>60 mm Hg for most patients. Second, maintaining patients on greater than 60% oxygen may have some associated lung toxicity. Therefore, if possible, keeping the inspired oxygen less than 60% is an important part of management. Of course, if high levels of inspired oxygen are necessary, you should not hesitate to use them. Please remember that patients on ventilators need not (and should not) have oxygen saturations of 100% or paO2 much greater than 60 mm Hg. PEEP (choice C) is the use of positive airway pressures at the end of expiration. PEEP is useful in hypoxic respiratory failure such as ARDS or cardiogenic pulmonary edema. Low levels of PEEP can be used in COPD to keep airways open. Our patient's oxygenation is acceptable so increasing PEEP would not be beneficial now. In addition, our patients blood pressure is only borderline acceptable. Increasing PEEP will decrease venous return to the heart and might lead to further reductions in blood pressures. High levels of PEEP might also predispose patients to barotrauma which is a form of ventilator induced lung damage. Making no adjustments (choice E) is not acceptable. This patient is severely acidotic and hypercarbic and should not be left in this state.
Image of page 59
A 45-year-old woman is planning a trip from the United States to Hong Kong on a direct flight. She comes to the office inquiring about advice for any travel precautions that she should take. She has fibrocystic disease of the breast and takes oral contraceptive pills. Physical examination is unremarkable. Her estimated
Image of page 60
Image of page 61

You've reached the end of your free preview.

Want to read all 105 pages?

  • Spring '14
  • Chronic obstructive pulmonary disease

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture