Vocal cord paralysis following intubation

Scalable and High-Throughput In Vitro Vibratory Platform for Vocal Fold Tissue Engineering Applications

The vocal folds (VFs) are constantly exposed to mechanical stimulation leading to changes in biomechanical properties, structure, and composition. The development of long-term strategies for VF treatment depends on the characterization of related cells, biomaterials, or engineered tissues in a controlled mechanical environment. Our aim was to design, develop, and characterize a scalable and high-throughput platform that mimics the mechanical microenvironment of the VFs in vitro. The platform consists of a 24-well plate fitted with a flexible membrane atop a waveguide equipped with piezoelectric speakers which allows for cells to be exposed to various phonatory stimuli. The displacements of the flexible membrane were characterized via Laser Doppler Vibrometry (LDV). Human VF fibroblasts and mesenchymal stem cells were seeded, exposed to various vibratory regimes, and the expression of pro-fibrotic and pro-inflammatory genes was analyzed. Compared to current bioreactor designs, the platform developed in this study can incorporate commercial assay formats ranging from 6- to 96-well plates which represents a significant improvement in scalability. This platform is modular and allows for tunable frequency regimes.

Vocal cord paralysis following general anesthesia with endotracheal intubation: a clinical review on 43 cases

Background

Vocal cord paralysis (VCP) is one of the most stressful experiences for patients undergoing general anesthesia. Moreover, it is a risk factor for aspiration pneumonia and may increase morbidity and mortality. We examined several clinical features of the condition by reviewing the medical records of patients who experienced VCP following general anesthesia.

Methods

We reviewed the medical records of 321 patients who consulted an otolaryngologist owing to hoarseness, sore throat, throat discomfort, or dysphagia after general anesthesia. Among these, we included in the present study 43 patients who were diagnosed with VCP by laryngoscopy, who did not have symptoms of suspected VCP before surgery, who had no past history of VCP, and for whom endotracheal intubation was not continued after surgery.

Results

The mean age of patients with VCP was 51.3 years. With respect to surgical site, the most common was upper limb surgery, performed in 12 cases (9 cases were performed in sitting posture. With respect to surgical duration, only 11 cases lasted less than 3 h, whereas 32 cases required a surgical duration longer than 3 h. The most common symptom of VCP was hoarseness. Nine of the patients with VCP recovered spontaneously, but VCP persisted in 13 cases until the final follow-up examination.

Conclusions

We hope that this study might call attention to the occurrence of VCP following general anesthesia. Moreover, it is necessary to further evaluate the reasons for the higher incidence of VCP in upper limb surgery performed in sitting posture.

Incidence and Risk Factors of Postoperative Vocal Cord Paralysis in 987 Patients After Cardiovascular Surgery

BACKGROUND

Vocal cord paralysis (VCP) after cardiovascular surgery can affect the postoperative outcome. The aim of the present study was to clarify the incidence of VCP after cardiovascular surgery and the relationship between the surgery characteristics and the risk of VCP.

METHODS

A total of 987 consecutive patients who underwent cardiovascular surgery (cardiac, n = 895; aortic, n = 92) were enrolled. We retrospectively assessed the incidence and the risk of VCP according to the length and types of surgery and the details of each VCP case and compared them between the aortic and the nonaortic group.

RESULTS

Twenty-three patients (2.3%: cardiac, n =15; aortic, n = 8) were expertly diagnosed with VCP (left, n = 19; right, n = 2; bilateral, n = 2). In the multivariate analysis, the risk for VCP increased with the duration of the operation (odds ratio [OR], 4.4, 95% confidence interval [CI] 1.7 to 11.4), and aortic procedures (OR, 5.6, CI 2.3 to 13.5) exhibited higher risk compared with coronary artery bypass grafting. Among the VCP cases, the incidence of poor outcomes (ie, bilateral VCP, repeated airway treatment, death within 6 months) was significantly higher in the aortic group (p = 0.016). All patients that were intubated for longer than 100 hours exhibited poor outcomes.

CONCLUSIONS

Aortic procedures and prolonged operation increase the risk of VCP. Severe VCP tended to be associated with aortic surgery and intubation for more than 100 hours.

Age and comorbidity as risk factors for vocal cord paralysis associated with tracheal intubation

BACKGROUND

Vocal cord paralysis after tracheal intubation may be attributed to ageing and comorbidity. However, the relationship between patient characteristics and the risk of vocal cord paralysis is unknown.

METHODS

We prospectively analysed data representing 31 241 consecutive surgery patients who underwent tracheal intubation to determine whether duration of intubation, age, sex, and cardiovascular, cerebrovascular, and metabolic diseases were risk factors for vocal cord paralysis associated with intubation. Patients with vocal cord paralysis from any other causes were excluded.

RESULTS

Twenty-four (0.077%) suffered vocal cord paralysis (left, 16 patients; right, 8 patients). The risk was increased when intubation lasted 3-6 h (odds ratio, 2.0; 95% confidence interval, 1.1-5.6; P = 0.002) or 6 h or more (odds ratio, 14.5; 95% confidence interval, 5.2-40.9; P < 0.0001). The risk was increased in patients aged 50-69 (odds ratio, 3.6; 95% confidence interval, 1.2-11.1; P = 0.02) and 70 yr or above (odds ratio, 3.9; 95% confidence interval, 1.2-12.8; P = 0.02). The risk was increased with diabetes mellitus (odds ratio, 2.5; 95% confidence interval, 1.1-7.3; P = 0.03) and hypertension (odds ratio, 2.1; 95% confidence interval, 1.1-6.0; P = 0.03).

CONCLUSIONS

The risk of vocal cord paralysis was increased three-fold in patients aged 50 or above, two-fold in patients intubated 3-6 h, 15-fold in patients intubated 6 h or more, and two-fold in patients with a history of diabetes mellitus or hypertension. Our results are informative for informed consent, patient counselling, and intubation decision-making.

[Not all vocal cord failure following thyroid surgery is recurrent paresis due to damage during operation. Statement of the German Interdisciplinary Study Group on Intraoperative Neuromonitoring of Thyroid Surgery concerning recurring paresis due to intubation]

Since the phoniatrician H. Bauer described the first case of recurrent laryngeal nerve palsy most likely caused by intubation some 45 years ago, several case reports have been published. However, systematic analyses regarding the frequency of recurrent laryngeal nerve palsies due to intubation are scarce, and none of them has used the proper methods to demonstrate clearly that such a mechanism exists. Currently available data justify the assumption that not every recurrent laryngeal nerve palsy following thyroid surgery is due to the operation itself and that the damage caused by intubation, however, may only account for a minority of these cases. The differential diagnosis of postoperative recurrent laryngeal nerve palsy requires the use of specific tools which go beyond simple laryngoscopy and include stroboscopy as well as intra- and extralaryngeal electromyography. A partial palsy of recurrent laryngeal nerve due to intubation would be associated with severe dysphonia or aphonia, not with dyspnea because of the typical intermediate position of the paralyzed vocal folds with a normal electromyographic function of the cricothyroid muscle. The use of these methods to identify the nature of postoperative recurrent laryngeal nerve palsy is recommended in cases of regular intraoperative neuromonitoring but postoperatively impaired function of the vocal cords.