Reducing Morbidity of Acute Respiratory Distress Syndrome in Hospitalized Patients: Preventing Nosocomial Infection or Aspiration

Sandra Huggins RN, BSN, CCRN

Disclosures

Topics in Advanced Practice Nursing eJournal. 2006;6(2) 

In This Article

Treatment Strategies and Interventions for ARDS

Chest x-rays that reveal any acute changes or "white-out" appearance should be managed aggressively. ARDS can develop and progress rapidly or over several days, so it is crucial to monitor changes in the patient's status along with daily chest films. Diffuse patchy infiltrates noted in the patient with no documented left ventricular dysfunction and refractory hypoxemia should raise suspicion of impending ARDS.[2,4,14]

Noninvasive ventilation modalities are becoming increasingly popular in the acute management of early respiratory compromise to reduce the occurrence of nosocomial pneumonia. Noninvasive positive-pressure ventilation can provide comparable ventilatory support without exposing the patient to microbial introduction and aspiration associated with intubation.[16] If the patient must be managed with an artificial airway and mechanical ventilation, choosing orotracheal intubation over nasotracheal intubation will reduce the incidence of nosocomial sinusitis and potential bacterial microaspiration.[17]

Rouby and colleagues[24] reported 73% of patients receiving mechanical ventilation via a nasotracheal tube developed a nosocomial sinusitis compared with only 34% in patients who were intubated orally. The same is true regarding orogastric tube placement as opposed to nasogastric tube placement, although the most favorable means of administering long-term enteral feedings would be gastrostomy or jejunostomy tube placement.[17]

Low tidal volume. The supportive foundation in mechanical ventilation demonstrated by the ARDS Network Study (ARDSnet) consists of the administration of lower tidal volumes in patients with ARDS. This study demonstrated improved mortality rates in patients who were mechanically ventilated using a 6-mL/kg tidal volume as opposed to those receiving a 12-mL/kg tidal volume.[25,26,27] In addition to lower tidal volumes, maintaining peak plateau pressures of less than 30 cm H2O can provide adequate oxygenation and avoid traumatic lung injury. Avoiding FIO2 supplementation above 65% can minimize O2 toxicity. O2 saturation of 88% and above is considered adequate in the ARDS scenario. The addition of the smallest increments of positive end-expiratory pressure (PEEP) needed to enhance arterial oxygenation can improve gas exchange via alveolar recruitment while minimizing atelectasis and alveolar collapse (Figure 2).[9] Be diligent in monitoring oxygen saturation in light of the patient's clinical response to ventilation.

Alternative ventilation. Other modalities in the treatment of ARDS include high-frequency ventilation, extracorporeal membrane oxygenation (ECMO), and inverse ratio ventilation. High-frequency ventilation is gaining popularity because it provides adequate gas exchange while avoiding traumatic lung injury and end-expiration alveolar collapse seen with traditional ventilation modalities. ECMO involves blood oxygenation outside the body through a veno-arterial or veno-venous access and is reserved for severe ARDS cases. Current survival rates associated with ECMO therapy have been as high as 80%.[4,5]

In inverse ratio ventilation, the inspiratory to expiratory (I/E) ratio is adjusted to 1:1 or 2:1 for a prolonged inspiratory time to improve oxygenation.[2] The APN caring for patients with these modalities must be knowledgeable about their effects and should remain diligent for subtle changes in the patient's condition.

Sedation and neuromuscular blockade. Another treatment to consider is sedation or neuromuscular blockade (NMB) to reduce anxiety and decrease oxygen consumption in ARDS patients.[4,5,28] Sedatives such as propofol and midazolam have been shown to lessen anxiety in mechanically ventilated patients; NMBs such as atracurium or cisatracurium can reduce the patient's respiratory effort in order to achieve maximum ventilatory control.[5]

Care of patients receiving these agents involves total physiologic and emotional support and anticipation of every need. Consider administration of an additional sedative and/or pain medication continuously if NMB administration is ordered. Drawbacks to NMBs include the concern that patients who are conscious and receiving NMBs may not be able to communicate pain, and that flaccid paralysis may cause profound anxiety. In addition, remember that the patient has no spontaneous respiratory effort while receiving NMBs and must receive adequate supplemental ventilation and constant presence and reassurance.

Investigational strategies in the treatment of ARDS. Steroid therapy to decrease the profound inflammatory process associated with ARDS remains controversial because steroid administration generally is not beneficial in the early stages of ARDS and can blunt infectious manifestations.[2,4,7,9] Another pharmacologic therapy, surfactant replacement therapy, has exhibited improved outcomes in neonates suffering from respiratory distress syndrome (RDS),[7,9,29] but has not shown to be substantially beneficial in reducing ARDS mortality rates in adult patients.[9,30,31] Multiple topics for future investigation have been identified in previously unsuccessful studies pertaining to treatment of ARDS.[9] Currently, however, the overall goal is to diagnose and treat the underlying insult in order to prevent ARDS progression.[2]

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