Comparison of cough reflex testing with videoendoscopy in recently extubated intensive care unit patients.

PURPOSE: Orotracheal intubation is known to impair cough reflex, but the validity of cough reflex testing (CRT) as a screening tool for silent aspiration in this population is unknown. MATERIAL AND METHODS: One hundred and six participants in a tertiary-level intensive care unit (ICU) underwent CRT and videoendoscopic evaluation of swallowing (VES) within 24 hours of extubation. Cough reflex threshold was established for each participant using nebulized citric acid. RESULTS: Thirty-nine (37%) participants had an absent cough to CRT. Thirteen (12%) participants aspirated on VES, 9 (69%) without a cough response. Sensitivity of CRT to identify silent aspiration was excellent, but specificity was poor. There was a significant correlation between intubation duration and presence of aspiration on VES (P= .0107). There was no significant correlation between silent aspiration on VES and length of intubation, age, sex, diagnosis at intensive care unit admission, indication for intubation, Acute Physiology and Chronic Health Evaluation III score, morphine equivalent dose, or time of testing postextubation. CONCLUSIONS: Intensive care unit patients are at increased risk of aspiration in the 24 hours following extubation, and an impaired cough reflex is common. However, CRT overidentifies risk of silent aspiration in this population.

Recovery of cough after extubation after coronary artery bypass grafting: A prospective study.

PURPOSE: This study aims to evaluate the effect of intubation for coronary artery bypass grafting (CABG) on the cough reflex, an important airway protection mechanism. MATERIALS: Eighty-six participants (70 males) underwent cough reflex texting (CRT) before intubation for CABG to establish baseline threshold for reflexive cough. Cough reflex texting was repeated within 2 hours of extubation and every morning and evening thereafter until the participant coughed at baseline level, withdrew, or was discharged from hospital. RESULTS: Sixty percent of participants had an absent cough reflex at CRT2 (x = 70 minutes). Participants varied in time to recovery of cough reflex. By CRT6, only 3 remaining participants persisted with an absent cough. Age, sex, or length of intubation had no significant impact on the time to recovery of cough reflex (P > .3). CONCLUSIONS: Absent cough reflex persists after CABG and may impact patients' ability to clear their airway in the event of aspiration. These results could contribute to better understanding postextubation dysphagia. More research is needed to determine if cough reflex is affected in the wider intensive care unit population postextubation and if CRT is a valid tool for detecting silent aspiration in this population.

An investigation into the stability and sterility of citric acid solutions used for cough reflex testing.

Citric acid is used in cough reflex testing in clinical and research settings to assess reflexive cough in patients at risk of swallowing disorders. To address a lack of knowledge in this area, this study investigated the stability and sterility of citric acid solutions. Triplicate solutions of citric acid (0.8 M) in isotonic saline were stored at 4 ± 2 °C for up to 28 days and analysed by high-performance liquid chromatography. Microbiological sterility of freshly prepared samples and bulk samples previously used for 2 weeks within the hospital was determined using a pour plate technique. Microbial survival in citric acid was determined by inoculating Staphylococcus aureus, Escherichia coli, or Candida albicans into citric acid solution and monitoring the number of colony-forming units/mL over 40 min. Citric acid solutions remained stable at 4 °C for 28 days (98.4 ± 1.8 % remained). The freshly prepared and clinical samples tested were sterile. However, viability studies revealed that citric acid solution allows for the survival of C. albicans but not for S. aureus or E. coli. The microbial survival study showed that citric acid kills S. aureus and E. coli but has no marked effect on C. albicans after 40 min. Citric acid samples at 0.8 M remained stable over the 4-week testing period, with viable microbial cells absent from samples tested. However, C. albicans has the ability to survive in citric acid solution if inadvertently introduced in practice. For this reason, in clinical and research practice it is suggested to use single-use aliquots prepared aseptically which can be stored for up to 28 days at 4 °C.