Study design and randomization
postoperative pain, neurological disease, anxiety, dementia, pain, Delirium, TAVR, PONV, hearing disabilities, bioprosthetic valve, Confusion
NEUROLOGICAL DISEASE
Adult patients who underwent elective TAVR procedure under general anaesthesia were considered to be eligible to be included in the study. Patients needed to understand German and hearing disabilities should not exceed the volume adjustment of the MP3 player. Exclusion criteria were neurological disease including severe dementia. Following enrolment of the study, patients underwent neurocognitive assessment using the Minimental State Examination (MMSE). Patients who scored below 10 points were excluded from the study. To ensure correct loudness of the tape the necessary volume of the MP3 player was adjusted using a test tape and documented.Two MP3 players (Intenso Music Mover™, 8 GB, Intenso GmbH, Vechta, Germany), connected to a headset (Sony MDR-ZX110AP™, Sony, Monato, Japan). One MP3 player contained the study tape and the other with an empty file, were marked with the number 1 or 2. Randomization of the numbers 1 and 2 was performed on a simple randomization base. Each randomization was kept in a sealed envelope. Following inclusion in the study an envelope was assigned to each participant.Patients in the intervention group listened to a 20-min-long audio file with background music and therapeutic suggestions followed by 10 min of silence, which was played repeatedly until the end of surgery. A different file was played to prepare the patients for emergence from anaesthesia, starting when volatile anaesthesia was stopped. Following hypnotherapeutic principles, the text included direct and indirect positive messages. It addressed topics like competence and care of the surgical and anaesthesiology team, pain regulation, dissociation to a save place, affirmation, anxiety control and confidence. The patients in the control group received an identical looking MP3-player with a blank audio file. For more details please see Nowak et al. [Anaesthesia was induced using Remifentanil (0.1–0.3 μg/kg/min), Oxycodon 50–100 μg/kg, Propofol 1.5–2.5 mg/kg and Rocuronium 0.3–0.5 mg/kg. Anaesthesia was maintained using Remifentanil (0.1–0.3 μg/kg/min) und Sevoflurane (0.6–0.7 MAC). All patients received an arterial line, a central venous line and a pacemaker for rapid pacing. The TAVR procedure was performed in a hybrid operating room and with the use of transoesophageal echocardiography. A balloon aortic valvuloplasty was performed followed by the insertion of a catheter sheath. The bioprosthetic valve, crimped onto a balloon catheter, was advanced across the native aortic valve. During rapid right ventricular pacing, balloon inflation of the crimped heart valve was expanded and was secured to the underlying aortic-valve annulus. Valve position and leak were controlled with TEE. At the end of surgery patients were extubated and transferred to the ICU where they stayed overnight. In general, patients were discharged from ICU the next day.Following induction of anaesthesia, a Bispectral Index electrode was placed on the forehead and connected to the Bispectral Index monitor (BIS™, Software Version 3.01, Medtronic, Minneapolis, USA) to record anaesthetic depth. BIS was recorded every minute and exported into an excel file. For analysis the mean BIS, BIS episodes below 40 and BIS phases below 40 for more than 5 min were analysed. To determine the relative duration of BIS episodes below 40 the ratio between the duration of recording and the duration of the low BIS episodes was calculated.A simple randomisation was performed by using the numbers 1 and 2 equally distributed. Each number was stored in a sealed envelope. After successfully finishing the MMSE an envelope was assigned to the patient. Two MP3-players each singed with the number 1 or 2 were used for the study. One with the study and one player the empty control tape. Prior to surgery, the attending anaesthesiologist who was not part of the study team, unsealed the envelope of the respected participant. The respective MP3-player was started and the headset was adjusted to the to the pre-registered loudness and put on the patients´ ears. At the end of surgery, the headset and BIS Monitoring were removed, the patients were extubated and transferred to the intermediate care unit.POD was detected by physicians who were blinded to the treatment and not involved in the anaesthetic procedure. Patients were tested 2 and 6 h post intervention on the day of surgery, and twice daily on day 1, and 3 in the morning and the evening, respectively and -if the patient developed POD- daily until day 5, using the CAM-ICU (Confusion Assessment Method) and the Nu-DESC (Nurse Delirium Screening Scale). Treatment of the POD was according to the responsible physician. Patients were evaluated for postoperative pain on the day of operation (2 and 6 h post-surgery) and on postoperative day 1 in the morning and the evening using the numerical pain rating scale (NPRS) ranging from 1–10. Analgesic medication was taken from the patients´ charts and was directed by the responsible physician. Patients were also evaluated for PONV, 2, 6 h following extubation and on postoperative day 1. Patient history and pre-existing conditions were taken from the patient charts.