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Dyspnea in mechanically ventilated critically ill patients*

Schmidt, Matthieu MD; Demoule, Alexandre MD, PhD; Polito, Andrea MD; Porchet, Raphaël MD; Aboab, Jerome MD; Siami, Shidasp MD; Morelot-Panzini, Capucine MD, PhD; Similowski, Thomas MD, PhD; Sharshar, Tarek MD, PhD

doi: 10.1097/CCM.0b013e31821e8779
Clinical Investigations

Objectives: Ensuring the comfort of intensive care unit patients is crucial. Although control of pain has been extensively addressed in this setting, data on dyspnea in mechanically ventilated patients are scant. The objective of this study was to assess the prevalence of dyspnea in mechanically ventilated patients, identify its clinical correlates, and examine its impact on clinical outcomes.

Design: Prospective 6-month observational study.

Setting: Two medical intensive care units within university hospitals.

Participants: Intubated or tracheotomized patients who were mechanically ventilated for >24 hrs. We enrolled 96 patients (age, 61 ± 18 yrs; Simplified Acute Physiology Score II 43 [interquartile range, 31–60]) as soon as they could answer symptom-related questions. Dyspnea was evaluated on a “yes–no” basis; if yes, it was followed by a visual analog scale and descriptor choice (“air hunger” and/or “respiratory effort”). Pain and anxiety were also assessed by visual analog scales.

Interventions: Ventilator settings adjustment in dyspneic patients.

Measurements and Main Results: Forty-five patients (47%) reported dyspnea (respiratory effort in seven cases, air hunger in 15, both in 16, and neither of these in seven). Dyspneic and nondyspneic patients did not differ in terms of age, Simplified Acute Physiology Score II, indication for mechanical ventilation, respiratory rate, clinical examination, chest radiograph, or blood gases. Dyspnea was significantly associated with anxiety (odd ratio [OR], 8.84; 95% confidence interval [CI], 3.26–24.0), assist-control ventilation (OR, 4.77; 95% CI, 1.60–4.3), and heart rate (OR, 1.33 per 10 beats/min; 95% CI, 1.02–1.75). Adjusting ventilator settings improved dyspnea in 35% of patients. Successful extubation within 3 days was significantly less frequent in patients whose dyspnea failed to recede after adjusting ventilator settings (five [17%] vs. 27 [40%]; p = .034).

Conclusions: Dyspnea is frequent, intense, and strongly associated with anxiety in mechanically ventilated patients. It can be sensitive to ventilator settings and seems to be associated with delayed extubation.

From the Assistance Publique–Hôpitaux de Paris (MS, AD, CM-P, T. Similowski), Service de Pneumologie et Réanimation Médicale, Groupe Hospitalier Pitié-Salpêtrière, Paris, France; Université Paris 6 Pierre et Marie Curie (MS, AD, CM-P, T. Similowski), Paris, France; Assistance Publique–Hôpitaux de Paris (AP, JA, T. Sharshar), Service de Réanimation Médicale, Hôpital Raymond Poincaré, Garches, France; Université Versailles Saint Quentin en Yvelines (AP, T. Sharshar), Versailles, France; Assistance Publique–Hôpitaux de Paris (RP), Département de Statistiques, Hôpital Saint Louis, Paris, France; and Service de Réanimation (SS), Centre Hospitalier d'Etampes, Etampes, France.

Both T. Similowski and T. Sharshar are last authors.

The authors have not disclosed any potential conflicts of interest.

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© 2011 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins