Abstract
Excess Secretions - An Important Impediment to Weaning
By Martin Mayse, M.D., Carol Roberts, R.N., David Litvak, M.D., Maya Salameh, B.S., Lloyd Friedman, M.D., and Mark D. Siegel, M.D. From the Yale University School of Medicine, Department of Internal Medicine, Pulmonary & Critical Care Section, New Haven, CT. Educational funding for Dr. Mayse provided by Cardiopulmonary Corp., Milford, CT. Special thanks to Klar Yaggi, M.D. and Joseph Quaranta, M.D..
Background. Weaning protocols have shortened the duration of mechanical ventilation for many patients with respiratory failure. For an important subset, however, several obstacles delay extubation, including persistence of the underlying disorder, hypoxia, respiratory muscle weakness, and inability to protect the airway. One important impediment to weaning- excess respiratory secretions- has received insufficient attention. The purpose of this preliminary study was to determine how often excess secretions delayed weaning from mechanical ventilation.
Methods. From 9/27/99 to 12/9/99, we performed a prospective, observational study in the Medical and Cardiac ICU's of Yale-New Haven Hospital (YNHH), designed to document the prevalence of various obstacles to weaning among a group of medical (non-surgical) patients intubated for respiratory failure. On 24 pre-determined days, each newly intubated patient was evaluated for inclusion in the study. Patients were excluded if they were intubated for less than 12 hours or if the intubation had taken place outside YNHH. Patients were followed until hospital discharge or until 21 days of mechanical ventilation were completed, whichever occurred first.
Obstacles to weaning were documented for each ventilator day. In addition to excess secretions, previously defined obstacles included- 1) unresolved underlying process, 2) FIO2>50% to maintain SaO2>90%, 3) PEEP>5 mmHg to maintain SaO2>90%, 4) expired minute ventilation > 15 l/min, 5) patient not over breathing the ventilator, 6) shock, 7) cardiac ischemia, 8) stroke expected to interfere with weaning, 9) active seizures, 10) airway obstruction, 11) excess sedation, and 12) “other.” Excess secretions were defined as the need for suctioning = every 2 hours, sustained for an 8-hour period. The frequency of suctioning was determined by examining the patient's ICU flow chart and/or asking the patient's nurse how often suctioning was performed.
Results. 29 patients were screened, of whom 4 were eliminated, either because they were intubated for less than 12 hours (2), or because they had been intubated outside YNHH (2). The remaining 25 were intubated 36 separate times, yielding a total of 190 ventilator days. Among these, there were 13 men and 12 women. The mean age was 59.2 years (range 28-90). The median APACHE II on ICU admission was 23 (range 9-33). Primary underlying illnesses in the 25 patients included CAD (7), COPD (5), cancer (3), AIDS (2), asthma (2), and other (6). The primary reasons for the 36 intubations were pneumonia (8, 4 in immune suppressed patients and 2 in COPD), CHF (6), airway protection (6, including GI bleeding, excess secretions, drug overdose), sepsis (3), asthma (2), PE (2), and other (9).
5/25 patients met our definition for excess secretions and had no other identified impediment to weaning on at least one ventilator day. Excess secretions were the sole identified impediment on 26/190 ventilator days. Despite excess secretions, 3/5 were placed on a total of 16 weaning trials. 14/16 trials ended in failure - defined as cessation of a trial by the primary team for the following reasons- tachypnea, tachycardia, hypotension, hypertension, hypoxia, increased work of breathing, diaphoresis, agitation, anxiety, and other. The most common reason for halting these 14 trials was tachypnea (10/14). Of the two successful trials, one led to extubation, but the patient was reintubated 53 hours later because of secretions.
Patients with excess secretions were intubated for a median of 8.7 days (interquartile range 8.1 to 21) compared to 2.8 days (interquartile range 1.9 to 5.3) in the remaining subjects (p < 0.001). The median ICU length of stay among patients with excess secretions was 16.7 days (interquartile range 10.6 to 21) compared to 4.7 days (interquartile range 3.5 to 7.4) in the remainder (p < 0.001). 4/5 patients with excess secretions required multiple intubations compared to 3/20 without excess secretions (p < 0.01).
Conclusions. Excess secretions are an important impediment to weaning, prolonging the duration of mechanical ventilation and ICU length of stay. The need to be suctioned more than every 2 hours predicted either a failed weaning trial or non-readiness for extubation in every case. Improved measures to manage excess secretions may expedite the return to independent breathing.