Disease specific thresholds for determining extubation readiness: The optimal negative inspiratory force for chronic obstructive pulmonary disease patients
Amir Vahedian-Azimi1, Farshid R Bashar2, Marina N Boushra3, Joseph W Quinn4, Andrew C Miller5
1 Trauma Research Center, Nursing Faculty, Baqiyatallah University of Medical Sciences, Tehran, Iran
2 Department of Anesthesia and Critical Care, Hamadan University of Medical Sciences, Hamadan, Iran
3 Department of Emergency Medicine, East Carolina University Brody School of Medicine, Greenville, NC, USA
4 Department of Emergency Medicine; Department of Internal Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, Vidant Medical Center, East Carolina University Brody School of Medicine, Greenville, NC, USA
5 Department of Emergency Medicine, East Carolina University Brody School of Medicine; Department of Emergency Medicine, Nazareth Hospital, Philadelphia, PA, USA
Dr. Andrew C Miller
Department of Emergency Medicine, Nazareth Hospital, 2601 Holme Avenue, 3rd Floor, Marian Building, Philadelphia, PA 19152
Source of Support: None, Conflict of Interest: None
Objectives: The negative inspiratory force (NIF) has been used to help clinicians predict a patient's likelihood of successful liberation from mechanical ventilation (MV). However, the utility of the traditional threshold of ≤−30 cmH2O may not be appropriate for patients with chronic obstructive pulmonary disease (COPD). This study aims to define the optimal predictive NIF threshold for COPD patients.
Methods: A prospective-observational multi-center study was conducted in intensive care units of six academic medical centers. All patients had COPD and were intubated for hypercapnic respiratory failure. The process of weaning from MV was conducted according to the defined hospital protocol. NIF was measured after 120 min of spontaneous breathing trial (SBT). The sensitivity, specificity, positive, and negative predictive value (PPV, NPV), positive and negative likelihood ratios (LR+, LR−) were calculated, and the diagnostic accuracy recorded.
Results: A total of 90 patients with COPD (39 males and 51 females) were included. Of these, 43 patients (47.8%) were successfully extubated whereas 47 patients (52.2%) failed SBT or required re-intubation (P = 0.654). The threshold value of ≤−25 cmH2O offered the optimal performance in COPD patients: area under the receiver operating characteristic (ROC) curves ROC curves 0.836, sensitivity 95.0%, specificity 86.0%, PPV 84.4%, and NPV 95.6%., LR+ 6.79, LR− 0.06, and the diagnostic accuracy 90.7%.
Conclusions: In mechanically ventilated COPD patients with hypercapnic respiratory failure, the NIF threshold of ≤−25 cmH2O was a moderate-to-good predictor for successful ventilator liberation, and outperforms the traditional threshold of ≤−30 cmH2O.