Better Anesthesia Technique: A Case Series of Cochlear Implants.

Cochlear implants are expensive surgeries. It was expected that by the end of the year 2021 about 80,000 cochlear implants will be shipped worldwide. Alone in India 500 cochlear implants are placed in a year. Patients for these procedures are mostly young children with prelingual deafness. They often pose challenges like anxiety, post operative nausea and vomiting, haemorrhage and CSF leak or flap necrosis. Parent child separation is another concern in a deaf paediatric patient. A meticulous anaesthetic management provides comfortable induction and a stable intra operative hemodynamics to give favourable outcomes. Copyright:

INTRODUCTION

Cochlear implants are very expensive electronic devices which require a careful surgical technique to place the internal compressor assembly within the mastoid antrum and connect the electrodes to the cochlear neurons. The surgical technique requires a team approach which includes the use of such anesthetic technique so as to maintain a bloodless surgical field with stable intraoperative hemodynamics. As such, the role of anesthesiologists is crucial during such expensive surgical procedures for a better outcome.[1]

The various challenges faced by anesthesiologists are time-consuming anesthesia, creation of condition for nerve stimulation, bloodless surgical field, and control of postoperative nausea and vomiting (PONV).[2]

Cochlear implants are extremely complex and costly electronic devices; therefore, the role of anesthesiologists is crucial for such expensive operations for better outcome. The induction of anesthesia can be done with thiopental or propofol with analgesia given with opioids.[3] Induction in children can be given by sevoflurane, attenuation of pressure response with preoperative dexmedetomidine, and PONV management by ondansetron (0.1 mg./kg) plus dexamethasone (0.15 mg/kg). Other complications are creation of condition for nerve stimulation and injury.

Cochlear implants are external and exceptionally complicated electronic devices. Most of the patients are children with hearing disability; therefore, preoperative counseling of children and their parents is essential for relieving anxiety. Parent presence and cooperation are essential as patients are young children.[4]

CASE DESCRIPTION

The present study was carried out on 15 patients with American Society of Anesthesiologists I grading who underwent cochlear implant in the ENT department operation theater of Rajendra Institute of Medical Sciences, Ranchi, on March 20–22, 2021.

Prior to surgery, further investigations, such as objective assessment of hearing, plain X-ray skull, and computed tomography temporal bone, were required. Radiographs were required to visualize the basal turn of cochlea and its patency.

The patients were screened for various congenital syndromes causing deaf-mutism, and such patients were excluded from the study.

All patients were identified and consent was verified before shifting them to the operation theater. Monitoring was done with electrocardiography, pulse oximetry, EtCo2, neuromuscular monitoring, and noninvasive blood pressure monitoring. All basal parameters were recorded.

All patients were premedicated with injection glycopyrrolate 5 μg.kg−1 and NSAID like paracetamol, rectally.[5] Preoxygenation with 100% oxygen was done for 3 min. Anesthesia induction was done with propofol 2–3 mg.kg−1 intravenous (i.v.) and maintained with end-tidal 1.5 MAC sevoflurane in 2:1 ratio mixture of nitrous oxide and oxygen; neuromuscular blockade was done with injection atracurium 0.5 mg.kg−1i.v. Intubation was done with an appropriate-sized endotracheal tube and checked for bilateral air entry and the tube was secured firmly in place. Attenuation of pressor response was done with dexmedetomidine 1 μgm.kg−1 just before intubation. It also provides stable hemodynamics intraoperatively. Patients were placed in mastoidectomy position. For PONV, we had given ondansetron 0.1 mg/kg and dexamethasone 0.15 mg/kg combination.[6]

Intraoperative blood loss was controlled with and mild hypotension. The mean arterial pressure (MAP) was kept around 60 mm/Hg throughout the surgery. As all patients were below 10 years of age, warming blankets were used to prevent hypothermia. Facial nerve preservation is important during surgery; therefore, before the identification via electrical stimulation of facial nerve, the effect of muscle relaxant was weaned off using the response of train-of-four stimulation, and anesthesia was maintained with propofol infusion during that time.

Cochlear implant is an expensive electrical device and can be damaged by electrical discharge from electrical cautery; hence, cautery was not used once cochlear implant was inserted. The duration of surgery was usually 4 h. Reversal was done with injection neostigmine (0.05 mg.kg−1) and injection glycopyrrolate (0.01 mg.kg−1).

Postoperative oxygenation with FiO2 100% for 8 h with 30 min of gap was given after every 1 h of oxygenation, to avoid hyperoxygenation. Parameters such as BP, SpO2, heart rate, MAP, DAP, and respiration rate were recorded every 5 min, 15 min, and then every 15 min up to 1 h and then after every 30 min till the end of surgery.

Table 1 shows that the demographic profile was similar with a mean body mass index of 16.41 ± 3.1 kg/m2.

Table 1

Demographic profile

	Mean (n=15)±SD
Sex (%)
Male	60
Female	40
Weight (kg) (mean)	14.73±1.78
Height (m) (mean)	0.932±0.1058
Age (years)	4.42±2.06
Duration of surgery (min)	222.08±40
BMI	16.41±3.1

SD: Standard deviation, BMI: Body mass index

The duration of surgery was 222.08 ± 40 min. There were no significant complications except that PONV occurred in two patients. There was incidence of fever in one patient and facial nerve palsy in one patient.

DISCUSSION

Table 2 depicts that PONV occurred roughly an hour postoperatively, though there was not much difference in relation to sex as there were only two cases of vomiting (n = 15), of which one was male and one female. However, there was a definite relation to the time of surgery. These two patients were exposed to surgery for more than mean operation time, i.e., 222.08 ± 40 min. They vomited 240–300 min postoperatively (P ≥ 0.05). Of total number of cases, there was 13.6% PONV. There was no repetition of vomiting for the next 24 h, so no rescue antiemetic was needed. Moreover, dexamethasone + ondansetron combination had a strong action as antiemetic. Table 3 shows MAP from the time of induction to the end of surgery of 15 cases as mean with SD. It was observed that during the first 30 min, there was a transient rise in MAP after induction. MAP more than 80 mm Hg−1 was quickly corrected by hyperventilation for 5 min and kept around 60 mm Hg−1. The transient rise of MAP after 15 min was obviously due to laryngoscopy, but since we gave dexmedetomidine, MAP was reduced to normal in 5 min. According to Table 3, the MAP never surged above 60 mm.hg−1 throughout operation. Control of PONV and maintenance of MAP around 60 mmHg seems to be the key strategy for our satisfactory postoperative outcomes, as there was no electrode displacement, flap necrosis, hematoma, and perilymph leakage. There was however transient facial palsy which recovered completely within a span of 2 months.

Table 2

Complications

Age (years)	Sex	Height (cm)	BMI	Duration (min)	Complications
					Fever	PONV	Flap necrosis	Hematoma	Leak	Facial palsy
3.5	Female	82	19.33	240	_	_	Nil	Nil	Nil	Nil
5	Male	112	13.57	300	_	Yes	Nil	Nil	Nil	Nil
5	Female	93	19.65	210	_	_	Nil	Nil	Nil	Nil
3	Male	83	18.87	290	_	_	Nil	Nil	Nil	Nil
5	Female	82	17.84	200	Yes	_	Nil	Nil	Nil	Nil
6	Male	100	14	240	_	_	Nil	Nil	Nil	Nil
3	Male	90	19.75	195	_	_	Nil	Nil	Nil	Nil
7	Female	84	18.42	210	_	_	Nil	Nil	Nil	Yes
2.3	Male	84	18.42	210	_	_	Nil	Nil	Nil	Nil
4	Male	98	13.53	210	_	_	Nil	Nil	Nil	Nil
4	Male	110	13.22	270	_	_	Nil	Nil	Nil	Nil
5	Male	97	21.25	300	_	Yes	Nil	Nil	Nil	Nil
5	Female	92	19.75	270	_	_	Nil	Nil	Nil	Nil
9	Male	110	14.87	220	_	_	Nil	Nil	Nil	Nil
3	Female	81	20	225	_	_	Nil	Nil	Nil	Nil

BMI=Body mass index, PONV=Postoperative nausea and vomiting

Table 3

Hemodynamic profile

Minutes	Pulse rate	MAP	SpO2	Respiration rate	SAP	DAP
0	123.73±10.26	64.13±5.1	99	21.6±1.3	95.46±1.2	53.28±4.1
5	116.06±68.13	68.13±0.3	100	22.0±2.3	111.26±3.1	52.53±3.2
15	128.33±2.1	77.22±5.8	100	22.5±1.1	115.33±2.2	63.93±1.1
30	124.13±3.8	60.2±3.2	99	22.4±1.1	90.06±1.4	56.66±4.1
45	112.31±5.5	64.4±3.1	100	22.7±3.8	91.6±3.4	46.73±6.6
90	108.93±4.4	53.3±6.8	100	20.9±2.2	96.8±2.1	65.2±4.6
150	107.26±8.1	62.4±4.8	100	22.53±2.4	88.8±3.6	63.66±2.3
180	104.26±3.2	62.8±3.9	100	22.06±1.2	89.93±2.2	58.33±3.3
210	101.66±3.3	63.4±4.4	100	21.8±0.8	93.86±3.8	68.02±3.4

MAP=Mean arterial pressure, SAP=Systolic arterial pressure, DAP=Diastolic arterial pressure

CONCLUSIONS

Cochlear implant is an expensive affair, and complications are not tolerable. About 500 cochlear implants have been done in India since 1994. Since then, the results are improving due to improving trends in anesthetic techniques. To end with, we conclude that PONV control and low MAP with good pain management are key factors for successful cochlear implants.

Financial support and sponsorship

Nil.

Conflict of interest

There are no conflicts of interest.