Acute respiratory failure COPD patients with

Doxapram is an analeptic that increases the depth of respirations (tidal volume) by stimulating the respiratory center in CNS respiratory rate may increase slightly. It may elevate BP by increasing cardiac output. Respiratory depression from opiates is reversed without affecting pain relief. It is indicated when one requires the stimulation of deep breathing in postoperative patients for reversal of respiratory depression caused by anesthesia (other than muscle relaxants) or drug overdose and as a temporary measure in acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD) who are not undergoing mechanical ventilation. 

Noninvasive positive-pressure ventilation (NPPV) provides ventilatory support with oxygen and pressurized airflow using a face or nasal mask with a tight seal but without endotracheal intubation. In patients with acute respiratory failure due to COPD exacerbations, NPPV was associated with lower mortality, lower intubation rates, shorter hospital stays, and greater improvements in serum pH in 1 hour compared with usual care. Use of NPPV reduces the complications that often arise with invasive mechanical ventilation. NPPV is not appropriate for patients with altered mental status, severe acidosis, respiratory arrest, or cardiovascular instability. 

Acetazolamide should be avoided in patients with severe COPD. These patients may be unable to increase their alveolar ventilation enough to compensate for the acid-base alterations induced by acetazolamide. In some patients, especially those with severe pulmonary disease, increased CO2 gradients or acidosis may lead to acute respiratory failure. Acetazolamide should be used cautiously in such patients, and the practitioner should use the lowest effective dose to reduce lOP... 

Enteral formulas (e.g., Pulmocare, NutriVent, and Respalor) marketed for use specifically by patients with pulmonary disease are also available. In comparison with standard formulas, these products contain a higher percentage of nonprotein calories as fat (>50%). Several studies have evaluated the use of these high-fat/low-carbohydrate products in patients with COPD and acute respiratory failure, and general results have been favorable." These speciahzed pulmonary EN products are calorically dense (1.5 kcal/mL), which may be helpful in feeding patients with severe ARDS or pulmonary edema and in others who may require fluid restriction. 

In a study of 183 COPD patients with acute respiratory failure, 10.4% remained mechanically ventilated 21 days after intubation (11). In the same ICU, the relative risk of remaining ventilated at day 21 was twice as high in patients intubated for acute lung injury (21 of 107) (42). One explanation for the latter observation is the presence of either critical illness polyneuropathy or ICU-acquired paresis (ICUAP). In a study of 95 patients ventilated for at least seven days, one quarter developed ICUAP, resulting in a longer duration of MV (18 vs. 8 days in patients without ICUAP) (43). 

In healthy volunteers, stimulation of the phrenic nerves elicits twitch pressures of 31 to 39 cmH20, whereas in patients with severe COPD, twitch pressures average 19 to 20 cmH20 (53,60). Twitch pressures in patients recovering from an episode of acute respiratory failure are about half of those recorded in ambulatory patients with severe COPD (Fig. 5) (59,61,62). This decrease is in keeping with respiratory muscle weakness in most of these patients. Respiratory muscle weakness in mechanically ventilated patients can result from preexisting conditions or from new-onset conditions (63). 

Figure 5 Transdiaphragmatic twitch pressure recorded in mechanically ventilated patients recovering from an episode of acute respiratory failure. Box represents range of transdiaphragmatic twitch pressures recorded in ambulatory patients with severe COPD. Most mechanically ventilated patients had evidence of diaphragmatic weakness [data from Ref. 62 (open circles), and from Ref 61 (closed circles)]. Abbreviation COPD, chronic obstructive pulmonary disease. Source From Refs. 44.

Menzies R, Gibbons W, Goldberg P. Determinants of weaning and survival among patients with COPD who require mechanical ventilation for acute respiratory failure. Chest 1989 95 398-405. 

Acute respiratory failure is the most common reason for admission to an ICU and 80% of mechanically ventilated patients resume spontaneous breathing after a few days (6). Of the remaining patients who cannot be weaned, those with chronic obstructive pulmonary disease (COPD) are often the most difficult to separate from the ventilator (7). Common obstacles to weaning include immobility and deconditioning prior to... 

NIV is often an effective treatment for patients with acute respiratory failure, especially when secondary to exacerbation of chronic obstructive pulmonary disease (COPD) (24). NIV is also utilized for long-term ventilation (LTV) of patients with chronic respiratory failure due to thoracic restriction or NMD. It is used less frequently for COPD as there is only limited evidence of its long-term effectiveness in this condition (25). In stable patients, NIV is affected by the type of interface used (26). 

As noted above, an important trend in the management of LTMV patients has been the proliferation of so-called LTAC facilities that receive most of their patients from acute care hospitals, often with tracheotomies, many of whom are undergoing weaning. LTAC facilities accept patients recovering slowly from acute respiratory failure, especially from COPD exacerbations or the acute respiratory distress syndrome (ARDS), reflecting the increasing survival related to use of NIV (6) and low tidal volume ventilation (21),... 

Figure 1 The management of respiratory failure in the United States. Many patients are admitted initially to an acute care hospital. If they wean ptomptiy, they may spend time in an LTAC hospital for rehabilitation, and eventually return home. If they fail to wean, they undergo tracheostomy and are transferred to an LTAC when stable. Weaning attempts continue, and a mincnity of patients return home the rest remain at the LTAC or are transferred to a SNF. Patients who deteriorate while at LTACs or at home return to the acute care hospital fOT stabilization. Some patients with chronic respiratory failure do not require acute care but are ventilated noninvasively and remain home. Abbreviations COPD, chronic obstructive pulmonary disease NIV, noninvasive ventilation LTAC, long-term acute care SNF, skilled nursing facility.

---