Effect of Controlled Hypotension on the Outcomes of Stapes Surgery

Keywords

otosclerosis - stapes surgery - controlled hypotension

Introduction

Otologic surgery, including stapes surgery (SS), requires optimal visibility of the surgical field. Due to image magnification by the microscope or endoscope, even residual bleeding can easily obstruct the operative field, increasing risks associated with inner ear suction and loss of anatomic landmarks. Furthermore, unlike other procedures, vascular supply of the middle ear does not allow other forms of hemostasis, such as clamping.

Multiple approaches, such as hyperventilation, patient positioning, and intraoperative controlled hypotension (CH), have been tried to improve this condition.[1] This concept of CH, which aims to provide an optimal surgical field, was established several decades ago,[2] and seeks to achieve a systolic blood pressure of 80 to 90 mmHg, to reduce the mean arterial pressure (MAP) to between 50 and 65 mmHg or to reduce it by 30%.[1] [3] This simultaneously optimizes the surgical field and enhances professional satisfaction in procedures such as tympanoplasty and sinonasal endoscopic surgery.[3] [4] [5] [6]

However, the effect on postoperative outcomes in SS is uncertain. The present study evaluates the impact of CH on surgical and postoperative outcomes in SS.

Methods

Study Design

We conducted a retrospective observational study in a tertiary hospital center with patients aged more than 18 years who had SS, from January 2017 to October 2022. Those who underwent revision SS, a simultaneous surgical procedure, or did not present complete audiometric and anesthetic data were excluded. Patients were divided into two groups according to the intraoperative MAP (IMAP) values: a group between 50 and 65 mmHg throughout the whole surgery, and a second group above 65 mmHg.

Data Collection

The data collected included age, sex, comorbidities, tympanogram, acoustic reflexes, and pre- and postoperative air and bone thresholds. Pure tone average (PTA) and air-bone gap (ABG) were registered. We classified surgical techniques and applied materials, such as type and size of the prosthesis, as well as oval window sealing. Moreover, data on operative time was registered. Both intra- (such as nerve damage and perilymphatic gusher) and postoperative (such as vertigo, tympanic perforation, hypoacusis, tinnitus, nerve impairment, and prosthesis dislocation) complications were assessed.

Anesthesia

During surgery, heart rate (HR) and MAP were recorded. Both were measured by the automated oscillographic method before the operation and at intervals of 10 or 15 minutes during the surgery (Datex-Ohmeda). Anesthetic induction was performed by 2 to 2.5 mg/kg propofol, 1 mcg/kg bolus of remifentanil, and 0.6 mg/kg of rocuronium in every patient. After endotracheal intubation, anesthesia was maintained with propofol, sevoflurane, and remifentanil. The patient's head was extended (15–30°) and rotated away from the surgeon according to the ear. The skin of the ear canal was infiltrated with 2% lidocaine, with a 1:100.000 adrenaline solution.

Data Analysis

The statistical analysis was conducted with IBM SPSS Statistics for Windows (IBM Corp.) software, version 27.0. The continuous variables were expressed as mean and standard deviation (SD) or median and interquartile range (IQR) values, and the categorical variables, as numbers and percentages. The student's t-test, the Mann-Whitney U test, Chi-squared test, and the Fisher's exact test were used according to variable type. Statistical significance was set as p < 0.05.

Results

A total of 206 patients underwent SS during the period evaluated. A total of 53 patients who were submitted to revision surgeries or associated with other procedures were excluded. An additional 54 patients were removed due to insufficient data. A final total of 99 were included in the study, of which 23 satisfied the CH criteria.

Patients' characteristics are presented in [Table 1]. Both groups did not differ in terms of age (45.2 ± 9 versus 44.5 ± 10.3 years; p = 0.779) or on sex ratios (65.2 versus 77.6%. p = 0.230). Preoperatively, the MAP values were not significantly different between the groups (92 ± 19.9 versus. 96.9 ± 18.1 mmHg; p = 0.284), as shown in [Table 2].

Table 1 Characteristics of the study sample

	50–65 mmHg (n = 23)	> 65 mmHg (n = 76)	p-value
Mean age in yearŝ	45.2 ± 9	44.5 ± 10.3	0.779
Female sex: n (%)	15 (65.2)	59 (77.6)	0.23
Medical history: n (%)
Hypertension	1 (4.3)	7 (9.2)	0.677
Diabetes mellitus	0 (0)	2 (2.6)	1
Smoking	2 (8.7)	4 (5.3)	0.621
Cardiovascular events	0 (0)	2 (2.6)	1
Bilateral disease: n (%)	11 (47.8)	39 (51.3)	0.769
Right ear: n (%)	11 (47.8)	41 (53.9)	0.606
Follow-up in months: median (range)	9 (11)	12 (14)	0.264

Table 2 Preoperative evaluation of the study sample

	50–65 mmHg (n = 23)	> 65 mmHg (n = 76)	p-value
Mean preoperative arterial pressure (mmHg)	92 ± 19.9	96.9 ± 18.1	0.284
Tympanogram: n (%)			0.096
A	12 (52.2)	48 (73.8)
As	11 (47.8)	16 (24.6)
C	0 (0)	1 (1.5)
Acoustic reflex: n (%)			0.361
Absent	21 (91.3)	46 (75.4)
Present	0 (0)	1 (1.6)
On/Off	2 (8.7)	14 (23)

[Table 3] portrays surgical parameters. The most common procedure in both groups was stapedotomy (CH: 78.3%; Non-CH: 81.6%; p = 0.765). A statistically significant difference was observed in the sealing method between the 2 groups (p < 0.001), specifically in the use of hemostatic gelatin sponge (CH: 13%; Non-CH: 35.5%; p = 0.04) and subcutaneous tissue (CH: 30.4%; Non-CH: 1.3%; p < 0.001). In the CH group, there were less sealing procedures (34.8%), while in the second group, sealing with perichondrium (36.8%) was favored. Intraoperative mean heart rate was similar between the 2 groups (CH: 66 ± 13.6 beats per minute [bpm]; Non-CH: 68 ± 10.4 bpm; p = 0.451).

Table 3 Surgical parameters of the study sample

	50–65 mmHg (n = 23)	> 65 mmHg (n = 76)	p-value
Stapedotomy: n (%)	18 (78.3)	62 (81.6)	0.765
Piston length (mm): n (%)			0.136
4	4 (19)	14 (18.7)
4.25	4 (19)	4 (5.3)
4.5	13 (62)	57 (76)
Piston diameter (mm): n (%)			0.44
0.4	3 (15.8)	5 (7)
0.6	15 (78.9)	57 (80.3)
0.8	1 (5.3)	9 (12.7)
Piston material: n (%)			0.080
Teflon	20 (87)	74 (97.4)
Titanium	3 (13)	2 (2.6)
Sealing material: n (%)			0.001
Absent	8 (34.8)	20 (26.3)	0.43
Hemostatic gelatin sponge	3 (13)	27 (35.5)	0.04
Perichondrium	4 (17.4)	28 (36.8)	0.081
Subcutaneous tissue	7 (30.4)	1 (1.3)	< 0.001
Blood clot	1 (4.3)	0 (0)	0.232
Stapedotomy opening: n (%)			1
Not otherwise specified	15 (65.2)	50 (65.8)
Manual perforator	7 (30.4)	22 (28.9)
Microdrill	1 (4.3)	4 (5.3)
Canalplasty: n (%)			0.158
Not performed	7 (30.4)	21 (27.6)
Curettage	13 (56.5)	30 (39.5)
Microdrill	3 (13)	25 (32.9)
Mean heart rate (beats per minute)	66 ± 13.6	68 ± 10.4	0.451

The non-CH surgeries showed a nonstatistically significant trend towards longer duration (CH: 71.4 ± 21.3 minutes; Non-CH: 83 ± 27.4 minutes; p = 0.065) as detailed in [Table 4]. No differences in complication rates were observed (CH: 39.1%; Non-CH: 48.7%; p = 0.421). Concerning audiometric data, both groups presented similar mean preoperative PTA (CH: 55.4 ± 11.3 dB; non-CH: 53.1 ± 16.2 dB; p = 0.525 and mean preoperative ABG values (CH: 28.1 ± 8.2 dB; non-CH: 28.5 ± 9.1 dB; p = 0.859).

Table 4 Audiological outcomes, operative time, and complications

	50–65 mmHg (n = 23)	> 65 mmHg (n = 76)	p-value
Mean operative time in minutes	71.4 ± 21.3	83 ± 27.4	0.065
Complications: n (%)	9 (39.1)	37 (48.7)	0.525
Preoperative period
Mean PTA	55.4 ± 11.3	53.1 ± 16.2	0.525
Mean ABG	28.1 ± 8.2	28.5 ± 9.1	0.859
Postoperative period
Mean PTA (dB)	31.6 ± 10.2	33 ± 13.1	0.722
Mean ABG (dB)	9.3 ± 8.3	10.1 ± 9	0.709
ΔABG (dB)	24 ± 13.1	19.7 ± 17	0.287

Abbreviations: ΔABG, closure of the air-bone gap; ABG, air-bone gap; PTA, pure tone average.

Neither the mean postoperative PTA values (CH: 31.6 ± 10.2 dB; Non-CH: 33 ± 17 dB; p = 0.722) nor the mean postoperative ABG values (CH: 9.3 ± 8.3 dB; Non-CH: 10.1 ± 9 dB; p = 0.709) nor the mean ABG closure (CH: 24 ± 13.1 dB; Non-CH: 19.7 ± 17 dB; p = 0.287) showed significant changes.

Discussion

To the best of our knowledge, this is the first paper to address the role of blood pressure control in the outcome of SS. The surgery is centered around the middle ear, addressing the stapes and oval window, while tympanoplasty focuses on the tympanic membrane, making SS more dependent on proper visualization of the middle ear. In our work, the non-CH surgeries were longer despite showing no statistically significant difference. Yet, other relevant factors should additionally be considered, namely surgeons' expertise, anatomical complexity, or the disease's specificities.

In the present study, both groups had similar audiometric results as well as complication rates. Despite adequate visibility of the operation field, as reported in previous studies,[7] [8] [9] this advantage may have limited impact on the outcome. The major purpose of CH, namely in orthopedic and maxillofacial surgery, is to reduce blood loss and, consequently, the need for transfusions.[10] [11] Praveen et al. demonstrated that, in orthognathic surgery, hypotensive patients had less blood loss compared to normotensive patients.[12] However, regarding otological surgery, this benefit is negligible, and the use of this technique is supported by its association with better surgical conditions.

Controlled hypotension is based on the reduction of vascular resistance, to reduce hemorrhage in the surgical field. However, there are other phenomena that optimize surgical visibility and are not specifically owed to hypotension. Optimal cardiac output may play a relevant role.

Furthermore, heart rate can be fundamental in achieving ideal conditions.[13] In the present study, this value was similar in both groups, limiting an appropriate evaluation of this parameter. Pharmaceutical agents may also be relevant to the proposed objectives. The use of remifentanil to control hypotension has been proven effective in adults and children.[7] [8] [9] Regarding tympanoplasty, several studies by Degoute et al. have demonstrated its effectiveness in maintaining hypotension and improving surgeon satisfaction.[7] [8] However, it appears that other substances can accomplish the same goal without affecting blood pressure. A study by Kosucu et al.,[14] which evaluated the use of dexmedetomidine in tympanoplasty, revealed it provided an adequate operating field without the need for simultaneous hypotension.

Furthermore, CH can, paradoxically, also be an unhelpful technique, increasing bleeding.[6] [14] It is recognized that the reduction of arterial hypotension may trigger local vasodilation. Moreover, hemorrhage in the operating field can be the result of a reflex tachycardia, which is known to happen under these conditions. One study showed the benefits of sodium nitroprusside in the surgical field only at very low blood pressure values.[6] Thus, by achieving optimal surgical conditions, patients may be exposed to the adverse effects of this technique.

Another important aspect is the technical complexity and health risks inherent in achieving this target blood pressure range. Patients with ischemia and hypertension face greater risks to attain a sustainable CH. Under these conditions, it is important to consider the risk of inadequate perfusion of vital organs, such as the brain and heart.[1] [15] However, this concern may be overestimated, and the medical impact of CH appears to be modest.[11] [16]

The present study has several limitations. Despite evaluating multiple parameters, it was not possible to classify some variables. Evaluating surgeon's subjective satisfaction in the operative field could serve as a bridge in understanding the relationship between blood pressure and postoperative results, presenting a compelling topic for future research.

The surgical procedures were performed by several surgeons. However, apart from the sealing method of choice, the surgical techniques were similar. Another notable limitation is the small sample size. This factor resulted from the extensive collection of operational and follow-up parameters. Finally, indirect blood pressure measurement, while less accurate than direct, remains a useful and practical method.[17]

Conclusion

Controlled hypotension in stapes surgery did not impact the audiometric outcomes or complication rates. However, it may have a potential role in surgery duration. These findings highlight the need to reconsider routine use of controlled hypotension in stapes surgery.

• References

• 1 Degoute CS. Controlled hypotension: a guide to drug choice. Drugs 2007; 67 (07) 1053-1076
• 2 Leigh JM. The history of controlled hypotension. Br J Anaesth 1975; 47 (07) 745-749
• 3 Dal D, Celiker V, Ozer E, Başgül E, Salman MA, Aypar U. Induced hypotension for tympanoplasty: a comparison of desflurane, isoflurane and sevoflurane. Eur J Anaesthesiol 2004; 21 (11) 902-906
• 4 Kol IO, Kaygusuz K, Yildirim A, Dogan M, Gursoy S, Yucel E, Mimaroglu C. Controlled hypotension with desflurane combined with esmolol or dexmedetomidine during tympanoplasty in adults: A double-blind, randomized, controlled trial. Curr Ther Res Clin Exp 2009; 70 (03) 197-208
• 5 Alkan A, Honca M, Alkan A, Güleç H, Horasanlı E. The efficacy of esmolol, remifentanil and nitroglycerin in controlled hypotension for functional endoscopic sinus surgery. Braz J Otorhinolaryngol 2021; 87 (03) 255-259
• 6 Boezaart AP, Van der Merwe J, Coetzee A. Comparison of sodium nitroprusside- and esmolol-induced controlled hypotension for functional endoscopic sinus surgery. Can J Anaesth 1995; 42 (5 Pt 1): 373-376
• 7 Degoute CS, Ray MJ, Manchon M, Dubreuil C, Banssillon V. Remifentanil and controlled hypotension; comparison with nitroprusside or esmolol during tympanoplasty. Can J Anaesth 2001; 48 (01) 20-27
• 8 Degoute CS, Ray MJ, Gueugniaud PY, Dubreuil C. Remifentanil induces consistent and sustained controlled hypotension in children during middle ear surgery. Can J Anaesth 2003; 50 (03) 270-276
• 9 Richa F, Yazigi A, Sleilaty G, Yazbeck P. Comparison between dexmedetomidine and remifentanil for controlled hypotension during tympanoplasty. Eur J Anaesthesiol 2008; 25 (05) 369-374
• 10 Lin S, McKenna SJ, Yao CF, Chen YR, Chen C. Effects of hypotensive anesthesia on reducing intraoperative blood loss, duration of operation, and quality of surgical field during orthognathic surgery: a systematic review and meta-analysis of randomized controlled trials. J Oral Maxillofac Surg 2017; 75 (01) 73-86
• 11 Choi WS, Samman N. Risks and benefits of deliberate hypotension in anaesthesia: a systematic review. Int J Oral Maxillofac Surg 2008; 37 (08) 687-703
• 12 Praveen K, Narayanan V, Muthusekhar MR, Baig MF. Hypotensive anaesthesia and blood loss in orthognathic surgery: a clinical study. Br J Oral Maxillofac Surg 2001; 39 (02) 138-140
• 13 Eberhart LH, Folz BJ, Wulf H, Geldner G. Intravenous anesthesia provides optimal surgical conditions during microscopic and endoscopic sinus surgery. Laryngoscope 2003; 113 (08) 1369-1373
• 14 Kosucu M, Tugcugil E, Cobanoglu B, Arslan E. Evaluation of the perioperative effects of dexmedetomidine on tympanoplasty operations. Am J Otolaryngol 2020; 41 (06) 102619
• 15 Aaslid R, Lindegaard KF, Sorteberg W, Nornes H. Cerebral autoregulation dynamics in humans. Stroke 1989; 20 (01) 45-52
• 16 Liu J, Zhong H, DeMeo D, Do H, Kirksey M, Della Valle AG, YaDeau J. Controlled hypotension during neuraxial anesthesia is not associated with increased odds of in-hospital common severe medical complications in patients undergoing elective primary total hip arthroplasty - A retrospective case control study. PLoS One 2021; 16 (04) e0248419
• 17 Gourdeau M, Martin R, Lamarche Y, Tétreault L. Oscillometry and direct blood pressure: a comparative clinical study during deliberate hypotension. Can Anaesth Soc J 1986; 33 (3 Pt 1): 300-307