Dyspnea in mechanically ventilated critically ill patients

Crit Care Med. 2011 Sep;39(9):2059-65. doi: 10.1097/CCM.0b013e31821e8779.


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.

MeSH terms

  • Aged
  • Anxiety / epidemiology
  • Confidence Intervals
  • Critical Illness
  • Dyspnea / epidemiology*
  • Dyspnea / etiology
  • Female
  • Humans
  • Intensive Care Units / statistics & numerical data
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Odds Ratio
  • Pain / epidemiology
  • Pain Measurement
  • Prevalence
  • Prospective Studies
  • Respiration, Artificial* / methods
  • Risk Factors
  • Statistics, Nonparametric