An observational study in Voice Disorder Due to Iatrogenic Factor, Endotracheal Intubation During Surgery and Thyroid Surgery, sponsored by Clinical Hospital Centre Zagreb. Enrolling by invitation at 1 site in Croatia. Open to participants aged 18 Years to 70 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-08-20.
Sponsored by Clinical Hospital Centre Zagreb · Observational
Introduction: Possible consequences of endotracheal intubation are post-intubation voice changes.
Hypothesis: Endotracheal intubation during head and neck surgery is associated with objective and perceptual voice disorders.
Research objective: To investigate the short-term and long-term effects of endotracheal intubation on voice quality during head and neck surgery.
Material, subjects, methodology and research design: A prospective observational cohort study that will include patients undergoing surgery and endotracheal intubation lasting up to 3 hours. Adult patients divided into three groups will be included in the research: thyroid surgery, parotid gland surgery and abdominal surgery. Videostroboscopy, perceptual and objective acoustic voice analysis will be recorded before surgery, on the second postoperative day, two weeks and 1 month after surgery.
Expected scientific contribution of the proposed research: The scientific contribution would be an understanding of the risk factors and the connection of voice disorders after endotracheal intubation, as well as the ability to determine differences in this risk in patients undergoing different operations.
study protocol has been published and is attached below
77 studies on the registry are indexed under Voice Disorders; 17 are open to participants now.
This study's planned enrollment of 180 is above the median of 100 across 23 observational studies indexed under Voice Disorders.
Browse Voice Disorders studies →Clinical Hospital Centre Zagreb is the lead sponsor of 32 studies on the registry; 8 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Patients scheduled for elective thyroid, head and neck surgery or abdominal surgery at the University Hospital Centre Zagreb. All eligible patients will be divided into three groups, as follows: patients scheduled for thyroid gland surgery; patients scheduled for some other type of head and neck operation that does not fall to exclusion criteria (parotidectomy, extirpation of congenital neck cyst, etc.); and control group including patients scheduled for operation other than the head and neck region. All operations will be performed by experienced operators with more than 100 annual procedures.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Patients undergoing scheduled thyroid surgery at the University Hospital Centre Zagreb under general endotracheal anesthesia without preoperative voice disorder regardless of the cause (previous operations or irradiation on the neck, and damage to the recurrent laryngeal nerve (RLN) during thyroidectomy).
Patients undergoing scheduled abdominal surgery at Day surgery of University Hospital Centre Zagreb under general anesthesia without preoperative voice disorder regardless of the cause (previous operations or irradiation on the neck, and damage to the recurrent laryngeal nerve (RLN) during thyroidectomy). This will include laparoscopic abdominal procedures and other minor abdominal procedures done in Day surgery, and will be control group for head and neck surgical procedures.
Patients undergoing scheduled head and neck surgeries beside thyroid surgery at the University Hospital Centre Zagreb under general endotracheal anesthesia without preoperative voice disorder regardless of the cause (previous operations or irradiation on the neck, and damage to the recurrent laryngeal nerve (RLN) during thyroidectomy).
Subjective analysis of voice changes before and after endotracheal intubation for thyroid surgery, other head and neck surgery and abdominal surgery using Voice Handicap Index (VHI)
The Voice Handicap Index (VHI) is one of the most frequently used self-assessment scales for voice disorders. The Croatian version was adapted and validated by Bonetti and Bonetti (2013), while Benšić et al. (2024) confirmed normative values for the Croatian language. The scale consists of 30 items divided into three subscales: \- Functional, emotional and physical component. Each item is rated on a 5-point Likert scale (0 = Never, 1 = Almost Never, 2 = Sometimes, 3 = Almost Always, 4 = Always), giving a total score from 0 to 120, with higher scores indicating greater perceived voice handicap. Participants will complete the VHI questionnaire at Baseline (within 7 days before surgery with endotracheal intubation) and at postoperative follow-up time points (Day 1, Week 2, and Week 4). The primary VHI outcome is the change in total score before and after surgery. Units of Measure: • Total score range: 0-120 Method of Administration: • Self-administered paper
Time frame: Preoperative (within 7 days before surgery), Postoperative Day 1, Week 2, and Week 4
Subjective analysis of voice changes before and after endotracheal intubation for thyroid surgery, other head and neck surgery and abdominal surgery using GRBAS Scale (Perceptual Voice Evaluation)
The perceptual voice assessment (GRBAS) will be conducted by two speech-language pathologists with several years of clinical experience. Each parameter-Grade, Roughness, Breathiness, Asthenia, and Strain-will be scored on a 4-point scale (0 = Normal, 1 = Slight, 2 = Moderate, 3 = Severe). The average of the two evaluators' scores will be taken, and in the case of significant discrepancies, a third evaluator will be consulted to reach consensus. Voice samples will be recorded at baseline and post-intervention at 4 time points total. The primary GRBAS outcome will be the change in the 'Grade' score; secondary analyses will include changes in R, B, A, and S. Units of Measure: • Ordinal scores (0-3) for each parameter
Time frame: Time Points: Preoperative (within 7 days before surgery), Postoperative Day 1, Week 2, and Week 4
Videostroboscopy Evaluation before and after surgery
Videostroboscopy uses an endoscope containing a built-in video camera and a stroboscope, which records phonation while the vocal cords are being filmed. The recording captures the frequency of vocal cord vibrations during voice production and provides an apparently slow-motion view of these vibrations. In the stroboscopic video, the movements of the vocal cords are slowed down enough to precisely follow their motion. This technique allows detailed observation of the amplitude and symmetry of vibrations, as well as the phase of vocal cord closure during voice production. It facilitates diagnosis of numerous physical problems with the vocal cords, including paresis resulting from injury to the recurrent laryngeal nerve. Evaluations will be performed pre- and post-intervention using a standardized protocol. 2 experienced phoniatrists will independently review the recordings to identify possible pathology in vocal fold motion or structural damage. No formal scoring system will be applied.
Time frame: Preoperative (within 7 days before surgery) and Postoperative day 1
Objective Acoustic and Aerodynamic Voice Analysis - changes in fundamental frequency before and after surgery
Objective voice evaluation will be performed using selected acoustic and aerodynamic measures. Voice assessment involves recording sustained phonation of the vowel /a/ in a sound-treated room using a calibrated digital recording system. The recordings will be acquired with a high-quality microphone positioned at a fixed distance of 30 cm from the participant's mouth, placed at a 45° angle. The sound signal will be analyzed using the LingWAVES SLP Suite Pro VPR software (WEVOSYS medical technology GmbH, Germany). This software converts the analog voice signal to digital form and processes it to extract relevant voice parameters. Parameters to be evaluated: • Fundamental frequency (F0) in Hz. Physiological reference values: • Fundamental frequency: Female: \~206 Hz, Male: \~120 Hz,
Time frame: Time Points: Preoperative (within 7 days before surgery), Postoperative Day 1, Week 2, and Week 4
Objective Acoustic and Aerodynamic Voice Analysis - changes in Intensity before and after surgery
Objective voice evaluation will be performed using selected acoustic and aerodynamic measures. Voice assessment involves recording sustained phonation of the vowel /a/ in a sound-treated room using a calibrated digital recording system. The recordings will be acquired with a high-quality microphone positioned at a fixed distance of 30 cm from the participant's mouth, placed at a 45° angle. The sound signal will be analyzed using the LingWAVES SLP Suite Pro VPR software (WEVOSYS medical technology GmbH, Germany). This software converts the analog voice signal to digital form and processes it to extract relevant voice parameters. Parameters to be evaluated: • Intensity (in dB) Physiological reference values: • Intensity: Female: 68-74 dB, Male: 68-76 dB
Time frame: Time Points: Preoperative (within 7 days before surgery), Postoperative Day 1, Week 2, and Week 4
Objective Acoustic and Aerodynamic Voice Analysis- changes in Jitter before and after surgery
Objective voice evaluation will be performed using selected acoustic and aerodynamic measures. Voice assessment involves recording sustained phonation of the vowel /a/ in a sound-treated room using a calibrated digital recording system. The recordings will be acquired with a high-quality microphone positioned at a fixed distance of 30 cm from the participant's mouth, placed at a 45° angle. The sound signal will be analyzed using the LingWAVES SLP Suite Pro VPR software (WEVOSYS medical technology GmbH, Germany). This software converts the analog voice signal to digital form and processes it to extract relevant voice parameters. Parameters to be evaluated: • Jitter (%) Physiological reference values: • Jitter: 0-0.5%
Time frame: Time Points: Preoperative (within 7 days before surgery), Postoperative Day 1, Week 2, and Week 4
Objective Acoustic and Aerodynamic Voice Analysis- changes in shimmer before and after surgery
Objective voice evaluation will be performed using selected acoustic and aerodynamic measures. Voice assessment involves recording sustained phonation of the vowel /a/ in a sound-treated room using a calibrated digital recording system. The recordings will be acquired with a high-quality microphone positioned at a fixed distance of 30 cm from the participant's mouth, placed at a 45° angle. The sound signal will be analyzed using the LingWAVES SLP Suite Pro VPR software (WEVOSYS medical technology GmbH, Germany). This software converts the analog voice signal to digital form and processes it to extract relevant voice parameters. Parameters to be evaluated: • Shimmer (%) Physiological reference values: • Shimmer: 0-5%
Time frame: Time Points: Preoperative (within 7 days before surgery), Postoperative Day 1, Week 2, and Week 4
Objective Acoustic and Aerodynamic Voice Analysis- changes in Maximum phonation time before and after surgery
Objective voice evaluation will be performed using selected acoustic and aerodynamic measures. Voice assessment involves recording sustained phonation of the vowel /a/ in a sound-treated room using a calibrated digital recording system. The recordings will be acquired with a high-quality microphone positioned at a fixed distance of 30 cm from the participant's mouth, placed at a 45° angle. The sound signal will be analyzed using the LingWAVES SLP Suite Pro VPR software (WEVOSYS medical technology GmbH, Germany). This software converts the analog voice signal to digital form and processes it to extract relevant voice parameters. Parameters to be evaluated: • Maximum phonation time (MPT, in seconds) Physiological reference values: • Maximum phonation time: Female: 15-25 sec, Male: 25-35 sec
Time frame: Time Points: Preoperative (within 7 days before surgery), Postoperative Day 1, Week 2, and Week 4
Plan to share: No — At the moment, we do not know other logopedic laboratory being able to perform the same audiometric evaluation.
Started Sep 2024 (actual). Primary completion is estimated for Dec 2025, 15 months after the start.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
No contact was published for this record. The registry link below has the sponsor’s details.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Clinical Hospital Centre Zagreb