Predictors of prolonged weaning among mechanically ventilated patients in respiratory intensive care unit

Mohammadien, Hamdy A.; Hassanin, Doaa G.; Hossien, Mona T; Ali, Mostafa I.

doi:10.21608/smj.2018.35798

Predictors of prolonged weaning among mechanically ventilated patients in respiratory intensive care unit

Document Type : Original Article

Authors

Departments of Chest, Faculty of Medicine, Sohag University* and Cairo University.

10.21608/smj.2018.35798

Abstract

Background: Weaning is an essential part of critically ill patients who are on mechanical ventilation. Weaning was classified into simple, difficult and prolonged. Some patients are easily weaned off and others require a more prolonged duration.
Methods: 52 patients admitted to the respiratory intensive care unit (RICU) and requiring mechanical ventilation were successfully weaned and classified into simple (20, 37.7%), difficult (20, 37.7%) and prolonged weaning (13, 24.5%). Factors associated with prolonged weaning and outcomes were determined.
Results: A total of 53 intubated patients admitted to the RICU (30 (56.6%) males), aged (59.8±14.3) years were included. The following factors are associated with prolonged weaning: ↓ed serum mg++(P< 0.0001) & CA++(P< 0.0001) , ↑ed BUN level (P= 0.001), ↑ed PaCO2 (P0.04), ↓ed SaO2% (P0.0001),presence of ≥2 co-morbidities (P0.02), prolonged duration of MV (P<0.0001) and long ICU stay (P<0.0001). There was no significant relation between prolonged weaning and Modes of MV (p0.2), also A-a gradient ↓ed in patients with prolonged weaning but not significant (P=0.5). In multivariate analysis, prolonged weaning was independently associated with serum Mg+ (OR 0.03, 95% CI 0.003–0.24, P <0.001), and SaO2% change (the beginning- the end of weaning trial) OR 0.91, 95%CI 0.83–0.99, P < 0.04). Regarding baseline serum Mg++ & tidal volume, the cutoff point for predicting prolonged weaning was (≤1.5 .mmol/l & ≤450 ml) with, sensitivity, specificity, PPV NPV and accuracy (61.5%, 92.5%, 72.7%, 88.1%, 77%, P ˂0.0001 and77%,55%, 36% 88%, 66%, P ˂ 0.02, respectively).The cutoff points of PaCO2 ≥49 mmHg & SaO2% ≤91 at first weaning trial & SaO2% change ≥5 (between the beginning and the end of a weaning trial) were strongly associated with prolonged weaning (P ˂0.02, ˂ 0.0001& ˂0.003, respectively). Prolonged weaning was significantly associated with high mortality rate (P˂ 0.0001).
Conclusions: Several factors were associated with prolonged weaning, however, when subjected to multivariate analysis, only serum Mg++& SaO2% change significantly predict prolonged weaning. Prolonged weaning is associated with increased ICU stay and higher rate of tracheostomy.
Clinical Implications: Prolonged mechanical ventilation is associated with higher rate of reintubation, tracheostomy rate, longer ICU stay and higher mortality. Identification and correction of factors associated with prolonged weaning may change the outcome and prognosis of these patients. In addition, early intervention such as tracheostomy is likely to benefit these patients

Keywords

References

1. BolesJ M, Bion J, Connors A ,et al., Weaning from mechanical ventilation .European Respiratory Journal. 2007; 29(5):1033-56.

2. Esteban A, Alia I, Ibañez J, et al., Modes of mechanical ventilation and weaning. A national survey of Spanish hospitals.The Spanish Lung Failure Collaborative Group.Chest.1994; 106:1188–1193.

3.Vallverdú I, Calaf N, Subirana M, Net A, Benito S, Mancebo J. Clinical characteristics, respiratory functional parameters, and outcome of a two-hours T-piece trial in patients weaning from mechanical ventilation. Am J RespirCrit Care Med:1998; 158:1855–1862.

4. Schönhofer B, Geiseler J, Dellweg D et al., Prolongedweaning: S2k-guidelinepublished by the German Respiratory Society. Pneumologie. 2014; 68: 19-75

5. Funk GC, Anders S, Breyer MK, Burghuber OC, Edelmann G, Heindl W, Hinterholzer G, Kohansal R, Schuster R, Schwarzmaier-D’Assie A, Valentin A, Hartl S.Incidence and outcome of weaning from mechanical ventilation according to new categories.EurRespir. 2010; J 35:88–94

6. Brochard L, Rauss A, Benito S, et al., Comparison of three methods of gradual withdrawal from ventilatory support during weaning from mechanical ventilation. Am J RespirCrit Care Med. 1994; 150:896–903.

7. Funk GC, Anders S, Breyer MK, et al., Incidence and outcome of weaning from mechanical ventilation according to new categories. EurRespir J. 2010;35: 88–94.

8. Goldwasser R, Farias A, Freitas EE, Saddy F, Amado V, Okamoto V. Mechanical ventilation of weaning interruption.J Bras Pneumol. 2007; 33(Suppl 2S):S128–136.

9. Patel KN, Ganatra KD, Bates JH, et al., Variation in the rapid shallow breathing index associated with common measurement techniques and conditions. Respir Care.2009; 54:1462–1466.

10. Ferrer M, Sellares J, Valencia M, Carrillo A, Gonzalez G, Badia JR, Nicolas JM, Torres A. Non-invasive ventilation after extubation in hypercapnic patients with chronic respiratory disorders: randomised controlled trial. Lancet. 2009: 374:1082–1088.

11. Brochard L. Pressure support is the preferred weaning method. As presented at the 5th International Consensus Conference in Intensive Care Medicine: Weaning from Mechanical Ventilation. Hosted by ERS, ATS, ESICM, SCCM and SRLF; Budapest, April 28–29, 2005.

12. Jacobo S, Miquel F. Predictors of prolonged weaning and survival during ventilator weaning in a respiratory ICU Intensive Care Med. 2011 May; 37(5):775-84.

13. Awaloei A, Luke’s St. Medical Center - Quezon City, Quezon, Philippines Predictors and Outcomes of Prolonged Weaning Among Intubated Patients on Mechanical Ventilation.China Critical Care chest.2016.02.168.

14. Adel Hassan A G, El-Komy M H, Gad D M et al., Assessment of weaning failure in chronic obstructive pulmonary disease patients under mechanical ventilation in Zagazig University Hospitals, Egyptian Journal of Chest Diseases and Tuberculosis. January 2017; 66 (1): 65-74

15. Thongprayoon C., Cheungpasitporn W., Srivali N., Erickson S. B. Admission serum magnesium levels and the risk of acute respiratory failure Int J ClinPract, November 2015, 69, 11, 1303–1308.

16. Conti G, Montini L, Pennisi MA, et al., A prospective, blinded evaluation of indexes proposed to predict weaning from mechanical ventilation. Intensive Care Med 2004; 30:830–836.

17.Gajic, Ognjen; SaqibDara; Jose Mendez; AbedolaAdensanya; Emir Festic; Sean Caples; RimkiRana; Jennifer StSauver; James Lymp; BekeleAfessa "Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation". Critical Care Medicine- Baltimore. 2004; 32 (9): 1817–1824.

18. MacIntyre NR. Respiratory mechanics in the patient who is weaning from the ventilator.Respir Care. 2005 Feb; 50(2):275-86.

19. Georgakas I, Afroditi K. Boutou, Georgia Pitsiou1, Ioannis Kioumis4, Milly Bitzani3, Kristina Matei5, Paraskevi Argyropoulou1, IoannisStanopoulos Central Venous Oxygen Saturation as a Predictor of a Successful Spontaneous Breathing Trial from Mechanical Ventilation: A Prospective, Nested Case-Control Study the Open Respiratory Medicine Journal ISSN: 2018, 12; 1874-3064.

20. Jubran, A, Mathru, M, Dries, D. Continuous recordings of mixed venous oxygen saturation during weaning from mechanical ventilation and the ramifications thereof .Am J RespirCrit Care Med. 1998; 158; 1763-9.