J Clin Monit Comput (2016) 30:655–660

DOI 10.1007/s10877-015-9768-6

ORIGINAL RESEARCH

Effect of controlled hypotension on regional cerebral oxygen

saturation during rhinoplasty: a prospective study
Ali Fuat Erdem1 • Gurkan Kayabasoglu2 • Ayca Tas Tuna1 • Onur Palabiyik3 •

Yakup Tomak1 • Serbulent Gokhan Beyaz1

Received: 16 February 2015 / Accepted: 9 September 2015 / Published online: 10 September 2015
Ó Springer Science+Business Media New York 2015

Abstract The aim of this study was to investigate the Keywords Controlled hypotension
Near infrared
effect of controlled hypotension on cerebral oxygen satu- spectroscopy
Cerebral oxygen saturation
Rhinoplasty
ration (rSO2) using near infrared spectroscopy (NIRS) and
evaluation of postoperative cognitive function in patients
undergoing rhinoplasty. Fifty adult patients who were 1 Introduction
scheduled for elective rhinoplasty surgery and required
controlled hypotension were enrolled in this prospective Controlled hypotension decreases arterial pressure to
study. Controlled hypotension was provided using a com- reduce blood loss and the need for transfusion during
bination of propofol and remifentanil infusion supple- surgery, as well as to improve the quality of the surgical
mented with nitroglycerin infusion as necessary. rSO2 was field [1]. Controlled hypotension is defined as a reduction
evaluated during controlled hypotension by NIRS. Cerebral of the systolic blood pressure to 80–90 mmHg, a reduction
desaturation was observed in 5 out of 50 patients (10 %) of mean arterial pressure (MAP) to 50–65 mmHg or a
during hypotensive anesthesia. The greatest decrease from 30 % reduction of baseline MAP [2]. The reduction of
baseline was 28 % when MAP was 57 mmHg. In both non- bleeding is essential in surgery of the middle ear, endo-
desaturated and desaturated patients, postoperative MMSE scopic sinus surgery, plastic and reconstructive micro-
scores were significantly lower than preoperative scores. surgery, ophthalmologic surgery and neurosurgery, which
There was a 4 % decrease in the non-desaturated patients all have low hemorrhagic potential, to ensure a clear sur-
and a 7 % decrease in the desaturated patients when pre- gical field [1, 2].
operative and postoperative MMSE scores were compared. Rhinoplasty is considered to be one of the most chal-
A decline in cognitive function 1 day after surgery was lenging procedures in both the field of aesthetic surgery
observed in 23 patients (46 %) and in all patients with and otolaryngology. The anatomical features of the nose
intraoperative cerebral desaturation. The current study along with the unique properties, which make the reshaping
showed that even if SpO2 is in the normal range, there of the tissue uncomplicated, compounded by the compli-
might be a decrease of more than 20 % in cerebral oxygen cation of intraoperative bleeding, all make the surgeon’s
saturation during controlled hypotension. postoperative goal more difficult to achieve. Many rhino-
plasty surgeons prefer to work with a controlled hypoten-
sive anesthesia. Decreased intraoperative bleeding allows
& Ayca Tas Tuna the surgeon to visualize the operative field better in turn
aycatas@yahoo.com
allowing for a better analysis of the tissue and a more
1
Department of Anesthesiology, Faculty of Medicine, Sakarya comfortable utilization of preferred techniques [3–5].
University, Sakarya, Turkey Controlled hypotension could result in tissue ischemia
2
Department of Otorhinolaryngology, Faculty of Medicine, of the vital organs and the inhibition of the autonomic
Sakarya University, Sakarya, Turkey nervous system. None of the current data indicate that
3
Department of Anesthesiology, Sakarya University Training controlled hypotension with a MAP between 50 and
and Research Hospital, Sakarya, Turkey 65 mmHg is a risk in young and healthy patients. However,

123
656 J Clin Monit Comput (2016) 30:655–660

most candidates for controlled hypotension have organ After preoxygenation, anesthesia was induced with
dysfunctions that are not detectable by a clinical exami- propofol (2 mg/kg), lidocaine (1 mg/kg), rocuronium
nation [1]. (0.6 mg/kg) and remifentanil (0.25 mcg/kg/min). After
Near infrared spectroscopy (NIRS) provides a continu- endotracheal intubation, ventilation was started using a
ous means of noninvasively monitoring the oxygenation of 60 % air-in-oxygen mixture (tidal volume, 8 mL/kg; res-
cerebral venous (75 %) and arterial (25 %) blood. NIRS piratory rate, 12 bpm). Anesthesia was maintained with
measures the ratio of oxyhemoglobin to total hemoglobin propofol (8–12 mg/kg/h) and remifentanil (0.1–0.3 mcg/
in a field beneath the sensor, and this ratio is expressed as a kg/min) infusion during anesthesia. All patients received
percentage of regional cerebral oxygen saturation (rSO2) IV saline at 5 mL/kg/h. After induction of anesthesia,
[6]. NIRS is widely used to provide real-time information hypotension was induced and maintained at a target MAP
on cerebral oxygenation in patients undergoing various of 50–60 mmHg with continuous infusion of propofol and
procedures, including cardiac [7], orthopedic [8], laparo- remifentanil. If the target MAP could not be induced,
scopic [9] and abdominal surgery [10]. However, the nitroglycerin infusion was started. When incidental
relationship between rSO2 and controlled hypotension has hypotension below the target MAP occurred, a bolus of
not been established in patients undergoing rhinoplasty. ephedrine was applied to restore MAP to the target level.
It was hypothesized that controlled hypotension would Cerebral desaturation was defined as a reduction of rSO2
reduce rSO2 during rhinoplasty. Therefore, the aim of this to lower than 80 % of baseline for C15 s. When cerebral
study was to investigate the effects of controlled desaturation occurred, a two-step treatment was planned:
hypotension in rSO2 using NIRS and evaluation of post- The first step was to check and correct anesthesia circuit,
operative cognitive function. fraction of inspired O2, Et-CO2 and MAP. If the first step
failed to restore an acceptable rSO2, propofol and
remifentanil infusion doses were decreased and MAP was
2 Methods increased with intravascular fluid administration and
ephedrine.
2.1 Study protocol The cognitive function of the patients was assessed
using the MMSE test 1 day before and 1 day after surgery.
After receiving approval from the local institutional A decrease in the MMSE score C2 points from baseline
research ethics committee and written informed consent was considered as an index of decline in cognitive
from each patient, 50 American Society of Anesthesiology function.
(ASA) I patients who were scheduled for elective rhino- The duration of surgery, duration of anesthesia, number
plasty and required controlled hypotension were enrolled in of patients for whom nitroglycerin infusion was required
this prospective study. Exclusion criteria were as follows: and the time that desaturation occurred were also recorded.
patients who did not give consent, ASA II and above, age
under 18 years, body mass index over 30 kg/m2, antico- 2.2 The INVOS system
agulation therapy, previous hypersensitivity to any of the
study drugs and/or a preoperative Mini Mental State We used an INVOS 5100C oximeter (Somanetics, Covi-
Examination (MMSE) score of 23 or less. dien, Minneapolis, USA), which provides a continuous,
The study patients were kept fasting following the non-invasive, real-time measurement of cerebral oxy-
standard guidelines and premedicated with 0.02 mg/kg of genation. The INVOS 5100 is a two-channel (right ? left)
intravenous (IV) midazolam 15 min prior to the induction NIRS cerebral oximeter which automatically registers
of anesthesia. In the operating room, all patients were in which sensor it is connected to and uses sensor-dependent
supine position. Standard monitoring (electrocardiogram, algorithms for the calculation of rSO2.
non-invasive blood pressure, pulse oximetry, temperature)
was applied. Further, rSO2 was bilateral monitored using 2.3 Statistical analysis
NIRS. Sensors for cerebral oximetry were placed bilater-
ally on the right and left sides of forehead before the The normality assumption was checked using the Shapiro–
induction of anesthesia. Wilk test. The paired-samples Wilcoxon test was used to
The patients’ age, weight and height were noted. Mea- compare MMSE. Nonparametric Spearman correlation
surements of MAP, heart rate (HR), peripheral oxygen analysis was used to analyse the relationship between MAP
saturation (SpO2), right and left rSO2, end-tidal carbon and rSO2. The distribution of gender among desaturated
dioxide (Et-CO2) and body temperature were recorded patients were analysed by Fisher’s exact test. For all
before induction of anesthesia (baseline), after induction of analyses, IBM SPSS version 21.0 was used and the sta-
anesthesia (0 min) and every 5 min thereafter. tistical significance was set at p \ 0.05.

123
J Clin Monit Comput (2016) 30:655–660 657

3 Results during surgery. One commonality in the studies is the

conclusion: controlled hypotensive anesthesia is essential
The demographic data and duration of anesthesia and in rhinoplasty. Unlike previous examples in the literature,
surgery of the non-desaturated and desaturated patients are our study aims to examine the limits of controlled
presented in Table 1. The changes in HR, MAP, SpO2, and hypotensive anesthesia, and as such, is the first of its kind
rSO2 are shown in Fig. 1. in rhinoplasty literature. Additionally, the findings of the
Cerebral desaturation was observed in 5 out of 50 study can be extended beyond rhinoplasty to any proce-
patients (10 %) during hypotensive anesthesia. The great- dures, which require controlled hypotensive anesthesia.
est decrease from baseline was 28 % when MAP was The goal of controlled hypotension is to maintain a
57 mmHg. None of the episodes of cerebral desaturation pressure which is sufficiently low to allow a reduction in
which occurred during hypotensive anesthesia were asso- bleeding without suppressing the microcirculatory
ciated with a reduction in SpO2 or a decrease in Et-CO2. In autoregulation of the vital organs (i.e. the brain, heart or
patients with cerebral desaturation, rSO2 recovered to kidney) [1]. A reduction of MAP to 55–65 mmHg or a
acceptable values with ephedrine and intravascular fluid decrease of 30 % from baseline is safe in terms of end
administration. organ perfusion and oxygen delivery [12].
Preoperative and postoperative MMSE scores of all To apply controlled hypotension, some anesthetic drugs
patients are shown in Table 2. In both non-desaturated and such as propofol, inhalation anesthetics and opioids are
desaturated patients, postoperative MMSE scores were used alone or in combination [1]. Propofol has become
significantly lower than preoperative scores (p \ 0.001 and popular in providing controlled hypotension; it has the
p = 0.042, respectively). There was a 4 % decrease in the characteristics of rapid onset and recovery times with a
non-desaturated patients and a 7 % decrease in the desat- short half-life and duration of action. Propofol seems to be
urated patients when preoperative and postoperative more effective in reducing blood loss than volatile anes-
MMSE scores were compared. A decline in cognitive thetics [13]. Remifentanil, a short-acting rapid-onset and
function 1 day after surgery was observed in 23 patients offset opioid, has a hypotension effect [14] that provides a
(46 %) and in all patients with intraoperative cerebral bloodless operative field in inducing controlled hypoten-
desaturation. To evaluate whether there was any individual sion with no need for additional potent hypotensive agents
change in rSO2 response to a lowering of MAP, right rSO2 [15]. Total intravenous anesthesia (TIVA) with remifen-
and left rSO2 were correlated with MAP each time. A tanil and propofol is a more effective technique to obtain
correlation between rSO2 and MAP could not be estab- reduced bleeding in rhinoplasty than fentanyl combined
lished during hypotensive anesthesia. with inhalation anesthesia [16]. In addition, TIVA can
reduce pressure to the desired level and maintain a
bloodless operative field when used for controlled
4 Discussion hypotension in ear surgery [2]. Many clinical studies have
shown that, TIVA with propofol and remifentanil is useful
The initial studies of controlled hypotensive anesthesia to achieve controlled hypotension.
during rhinoplasty published in 1968 by Chayen and Cerebral oxygenation can be measured using invasive or
Kaplan [11]. In this area they have focused on the types of non-invasive methods. Unlike invasive methods such
anesthetics and their effect on controlled hypotension jugular bulb oximetry and brain tissue oxygen tension

Table 1 Demographic and clinical data of the non-desaturated and desaturated patients
Variable Non-desaturated patients (n = 45) Desaturated patients (n = 5) p value

Age (year) 34.17 ± 10.04 32.80 ± 13.36 0.683

Gender (M/F) 22/23 3/2 0.999
Weight (kg) 71.71 ± 11.39 66.00 ± 10.83 0.311
Duration of anesthesia (min) 90.00 ± 25.95 101.00 ± 27.47 0.359
Duration of surgery (min) 78.31 ± 23.41 91.80 ± 25.29 0.203
Time of desaturation (min) – 42.00 ± 28.28 –
Number of patients that nitroglycerin infusion was applied 17 (37.7 %) 2 (40 %) 0.922
Data are presented as mean ± SD or n
MMSE minimental state examination

123
658 J Clin Monit Comput (2016) 30:655–660

Fig. 1 The levels of HR, MAP, HR (beats/min)

SpO2, RrSO2 and LrSO2 (values 100
are mean ± SD. HR heart rate, 90
MAP mean arterial pressure, 80
70
SpO2 peripheral oxygen 60
saturation, RrSO2 right regional 50
cerebral oxygen saturation, 40
30
LrSO2 left regional cerebral 20
oxygen saturation) 10
0
MAP (mm Hg)
100
90
80
70
60
50
40
30
20
10
0
SpO2 (%)
100
99
98
97
96
95
RrSO2 (%)
100
90
80
70
60
50
40
30
20
10
0
LrSO2 (%)
100
90
80
70
60
50
40
30
20
10
0

Table 2 MMSE scores of the

Pre-operative Postoperative 1st day p value
patients
Non-desaturated patients (n = 45) 28.4 ± 1.45 27.0 ± 1.98 \0.001
Desaturated patients (n = 5) 29.2 ± 1.09 27.0 ± 1.22 0.042
Data are presented as mean ± SD
MMSE minimental state examination
p \ 0.05

123
J Clin Monit Comput (2016) 30:655–660 659

sensors, NIRS is applied easily. NIRS and invasive meth- 1 day after surgery and there wasn’t a control group to
ods of monitored cerebral oxygenation have similar effects compare effects of controlled hypotension among the
[17–19]. patients with hypotension or not.
Absolute rSO2 below 40 and a decline of more than In conclusion, the results of the current study showed
25 % from the baseline are associated with neurologic that even if SpO2 is in the normal range, there might be a
dysfunction and adverse outcomes [20]. A reduction of decrease of more than 20 % in cerebral oxygen saturation
15–20 % from the baseline or a reduction below 50 has during controlled hypotension. Furthermore, for NIRS-
been used as a critical threshold for concern and initiation based cerebral oximetry during controlled hypotension, the
of interventions [21, 22]. Therefore, in our study, a INVOS cerebral oximeter may be a helpful monitoring tool
reduction in rSO2 of 20 % from the baseline was accepted for detecting real-time rSO2 changes.
as threshold and when a decline of more than 20 %
Compliance with ethical standards
occurred, controlled hypotension was stopped and rSO2
recovered to acceptable values. Conflict of interest The authors declare that they have no conflict
In a study which investigated the effects of beach-chair of interest.
position and induced hypotension on rSO2 in patients
undergoing arthroscopic shoulder surgery, the beach-chair
position combined with induced hypotension decreased
rSO2; moreover, cerebral desaturation was seen in two References
cases whose MAP value decreased below 60 and
55 mmHg. However, a decline in cognitive function mea- 1. Degoute CS. Controlled hypotension: a guide to drug choice.
sured by MMSE was not observed in any of the patients Drugs. 2007;67:1053–76.
[8]. In an another study which assessed the effects of 2. Degoute CS, Ray MJ, Manchon M, Dubreuil C, Banssillon V.
Remifentanil and controlled hypotension; comparison with
controlled hypotension by using nitroglycerin and sodium nitroprusside or esmolol during tympanoplasty. Can J
nicardipine on rSO2 and postoperative cognitive function in Anesth. 2001;48:20–7.
patients undergoing orthognathic surgery, when MAP 3. Jacobi KE, Bohm BE, Rickauer AJ, Jacobi C, Hemmerling TM.
values were reduced to 60–65 mmHg, cerebral desatura- Moderate controlled hypotension with sodium nitroprusside does
not improve surgical conditions or decrease blood loss in endo-
tion or decreased MMSE scores were not observed in any scopic sinus surgery. J Clin Anesth. 2000;12:202–7.
of the patients [23]. In the present research, when MAP 4. Koşucu M, Omür S, Beşir A, Uraloğlu M, Topbaş M, Livaoğlu
decreased to 50–60 mmHg, cerebral desaturation was M. Effects of perioperative remifentanil with controlled
observed in five patients. hypotension on intraoperative bleeding and postoperative edema
and ecchymosis in open rhinoplasty. J Craniofac Surg.
During controlled hypotension, if MAP reduces to the 2014;25:471–5.
extent that it impairs cerebral autoregulation, postoperative 5. Tuncel U, Turan A, Bayraktar MA, Erkorkmaz U, Kostakoglu N.
cognitive dysfunction (POCD) could occur. The possible Efficacy of dexamethasone with controlled hypotension on
risk factors contributing to the development of POCD intraoperative bleeding, postoperative oedema and ecchymosis in
rhinoplasty. J Craniomaxillofac Surg. 2013;41:124–8.
include age, postoperative cognitive function (POCF), 6. Tobias JD. Cerebral oxygenation monitoring: near-infrared
operation time, hypoperfusion, embolism, postoperative spectroscopy. Expert Rev Med Devices. 2006;3:235–43.
pain, respiratory complications and infections [24]. In a 7. Yao FS, Tseng CC, Ho CY, Levin SK, Illner P. Cerebral oxygen
study which assessed cognitive outcomes after controlled desaturation is associated with early postoperative neuropsycho-
logical dysfunction in patients undergoing cardiac surgery.
hypotension where MAP was reduced to 45–55 or J Cardiothorac Vasc Anesth. 2004;18:552–8.
55–70 mmHg in 235 elderly patients when compared with 8. Lee JH, Min KT, Chun YM, Kim EJ, Choi SH. Effects of beach-
preoperative neuropsychological testing, no impairment in chair position and induced hypotension on cerebral oxygen sat-
POCF was noted at 1 week or 4 months postoperatively uration in patients undergoing arthroscopic shoulder surgery.
Arthroscopy. 2011;27:889–94.
[25]. None of these studies reported that controlled 9. Li XM, Shao MT, Wang JJ, Wang YL. Relationship between
hypotension decreased MMSE scores with or without the post-operative cognitive dysfunction and regional cerebral oxy-
observation of cerebral desaturation [5, 23]. In contrast to gen saturation and b-amiloid protein. J Zhejiang Univ Sci B.
these studies, in the present research, when compared with 2014;15:870–8.
10. Casati A, Fanelli G, Pietropaoli P, Proietti R, Tufano R, Danelli
preoperative baseline MMSE scores, a significant decline G, Fierro G, De Cosmo G, Servillo G. Continuous monitor-
in cognitive function was noted at 1 day postoperatively in ing of cerebral oxygen saturation in elderly patients undergoing
both desaturated and non-desaturated patients. Moreover, major abdominal surgery minimizes brain exposure to potential
this decline was more pronounced in desaturated patients. hypoxia. Anesth Analg. 2005;101:740–7.
11. Chayen M, Kaplan I. Methoxyflurane and controlled hypotension
The limitations of the current study are that we only in corrective rhinoplasty. Br J Plast Surg. 1968;21:168–9.
evaluated cognitive function using the MMSE test and 12. Petrozza PH. Induced hypotension. Int Anesth Clin.
assessed the MMSE test postoperatively only once, at 1990;28:223–9.

123
660 J Clin Monit Comput (2016) 30:655–660

13. Boonmak S, Boonmak P, Laopaiboon M. Deliberate hypotension 20. Edmonds HL Jr, Ganzel BL, Austin EH III. Cerebral oximetry for
with propofol under anesthesia for functional endoscopic sinus cardiac and vascular surgery. Semin Cardiothorac Vasc Anesth.
surgery (FESS). Cochrane Database Syst Rev. 2013;6:CD006623. 2004;8:147–66.
doi:10.1002/14651858.CD006623.pub2. 21. Samra SK, Dy EA, Welch K, Dorje P, Zelenock GB, Stanley JC.
14. Patel SS, Spencer CM. Remifentanil. Drugs. 1996;52:417–28. Evaluation of a cerebral oximeter as a monitor of cerebral
15. Degoute CS, Ray MJ, Gueugniaud PY, Dubreuil C. Remifentanil ischemia during carotid endarterectomy. Anesthesiology.
induces consistent and sustained controlled hypotension in chil- 2000;93:964–70.
dren during middle ear surgery. Can J Anaesth. 2003;50:270–6. 22. Rigamonti A, Scandroglio M, Minicucci F, Magrin S, Carozzo A,
16. Tirelli G, Bigarini S, Russolo M, Lucangelo U, Gullo A. Total Casati A. A clinical evaluation of near-infrared cerebral oximetry
intravenous anaesthesia in endoscopic sinus-nasal surgery. Acta in the awake patient to monitor cerebral perfusion during carotid
Otorhinolaryngol Ital. 2004;24:137–44. endarterectomy. J Clin Anesth. 2005;17:426–30.
17. McLeod AD, Igielman F, Elwell C, Cope M, Smith M. Mea- 23. Choi SH, Lee SJ, Jung YS, Shin YS, Jun DB, Hwang KH, Liu J,
suring cerebral oxygenation during normobaric hyperoxia: a Kim KJ. Nitroglycerin- and nicardipine-induced hypotension
comparison of tissue microprobes, near-infrared spectroscopy and does not affect cerebral oxygen saturation and postoperative
jugular venous oximetry in head injury. Anesth Analg. cognitive function in patients undergoing orthognathic surgery.
2003;97:851–6. J Oral Maxillofac Surg. 2008;66:2104–9.
18. Kim MB, Ward DS, Cartwright CR, Kolano J, Chlebowski S, 24. Krenk L, Rasmussen LS, Kehlet H. New insights into the
Henson LC. Estimation of jugular venous O2 saturation from pathophysiology of postoperative cognitive dysfunction. Acta
cerebral oximetry or arterial O2 saturation during isocapnic Anaesthesiol Scand. 2010;54:951–6.
hypoxia. J Clin Monit Comput. 2000;16:191–9. 25. Williams-Russo P, Sharrock NE, Mattis S, Liguori GA, Mancuso
19. Daubeney PE, Pilkington SN, Janke E, Charlton GA, Smith DC, C, Peterson MG, Holllenber J, Ranawat C, Salvati E, Sculco T.
Webber SA. Cerebral oxygenation measured by near-infrared Randomized trial of hypotensive epidural anesthesia in older
spectroscopy: comparison with jugular bulb oximetry. Ann patients. Anethesiology. 1999;91:926–35.
Thorac Surg. 1996;61:930–4.

123