Abstract
Background: Whether nerve block improves the quality of conscious sedation (CS) in patients undergoing transcatheter aortic valve implantation (TAVI) is unclear. This study investigated whether fascia iliaca block (FIB) reduced the remifentanil requirement and relieved pain in CS for TAVI.
Methods and Results: This prospective study randomized 72 patients scheduled for elective TAVI under CS into 2 groups, with (FIB) and without (control) FIB (n=36 in each group). The sedation targeted a Bispectral Index <90 with a Richmond Agitation-Sedation Scale of −2 to −1. Dexmedetomidine (0.7 µg/kg, i.v.) combined with remifentanil (0.03 µg/kg/min, i.v.) and propofol (0.3 mg/kg/h, i.v.) was used to commence sedation. FIB using 30 mL of 0.185% ropivacaine was implemented 2 min before TAVI. Patient sedation was maintained with dexmedetomidine (0.4 µg/kg/h, i.v.) supplemented with remifentanil (0–0.02 µg/kg/min, i.v.). Remifentanil (20 µg, i.v.) was used as a rescue dose for intraprocedural pain. Compared with the control group, FIB reduced the both the total (median [interquartile range] 83.0 [65.0–98.0] vs. 34.5 [26.0/45.8)] µg; P<0.001) and continuous (25.3 [20.9/31.5] vs. 9.5 [6.8/12.5] ng/kg/min; P<0.001) doses of remifentanil administered.
Conclusions: FIB reduced the remifentanil requirement and relieved pain in patients undergoing TAVI with CS. Therefore, FIB improved the quality of CS in TAVI.
Previous studies have demonstrated that sedation can possibly be used in patients with aortic stenosis undergoing transfemoral transcatheter aortic valve implantation (TAVI).1–3 However, deep sedation frequently causes adverse respiratory events, including the need for maneuvers to secure the airways and bag-mask ventilation.1 The higher incidence of adverse events in deep sedation results in a clinician preference for conscious sedation for patients undergoing transfemoral TAVI.4 Indeed, a recent study documented that, among patients undergoing TAVI, the length of hospital stay was shorter and both in-hospital and 30-day mortality were lower with conscious sedation than general anesthesia.2 In contrast, another study comparing conscious sedation with general anesthesia in patients undergoing transfemoral TAVI reported similar outcomes for the composite of all-cause mortality, stroke, myocardial infarction, infection requiring antibiotic treatment, and acute kidney injury at the 30-day follow-up.3 These results suggest that transfemoral TAVI under conscious sedation is feasible, although it cannot be concluded that conscious sedation is superior to general anesthesia in the population.2–4
Insertion of an expandable sheath during transfemoral TAVI causes significant pain, with local analgesic techniques commonly used to alleviate painful conditions under conscious sedation. A recent study documented that femoral nerve block without sedation enabled the detection of post-TAVI aortic regurgitation more effectively than deep sedation.5 However, that preliminary investigation did not evaluate how a nerve block may be advantageous for patients undergoing transfemoral TAVI, especially in terms of pain relief.5 Fascia iliaca block (FIB), also referred to fascia iliaca compartment block, affects several nerves simultaneously, including the lateral femoral cutaneous, obturator, and femoral nerves.6 In addition, FIB, but not femoral nerve block, occurs at a sufficient distance from important inguinal neurovascular structures and has been safely used for pain management in acute hip fracture.6 These results indicate that FIB may be superior to sole femoral nerve block in terms of alleviating pain without complications, even though both methods appear similar. However, whether a supplemental nerve block technique will improve the quality of conscious sedation, including pain relief, in patients undergoing transfemoral TAVI has not yet been determined.
We hypothesized that FIB would effectively relieve pain without complications in patients undergoing transfemoral TAVI. Therefore, the aim of the present study was to determine whether FIB improves the quality of conscious sedation, including reducing patients’ requirements for remifentanil.
Methods
This single-center prospective double-blind study with balanced randomization (1 : 1) was performed between March 2021 and March 2022 at the Departments of Anesthesiology and Cardiology, Toyohashi Heart Center (Toyohashi, Japan). Ethics approval for the study (#210105) was provided by the Ethics Committee of Toyohashi Heart Center on January 26, 2021. In addition, this study was registered in the University Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN000043286). Written informed consent was obtained from all patients before enrollment. The study was performed in accordance with the Declaration of Helsinki and the ethical standards of the responsible committee on human experimentation.
Patients aged >20 years with severe aortic stenosis who underwent transfemoral Sapien 3TM
(Edwards Lifesciences Corp., Irvine, CA, USA) or CoreValveTM
(Medtronic, Minneapolis, MN, USA) implantation were included in the study. Cardiologists determined whether each patient was eligible for transfemoral TAVI and which prosthesis was adequate for treatment. Based on the findings of a previous study that compared sedation and general anesthesia for TAVI,1 patients with a predicted difficult airway, severe pulmonary arterial hypertension (systolic pulmonary arterial pressure >60 mmHg), continuous positive airway pressure therapy for obstructive sleep apnea, former/current alcohol or drug abuse, liver cirrhosis, neurocognitive/neurodegenerative disease or psychiatric disorder, or using antidepressants/sedatives were excluded. Secondary exclusion criteria were perioperative emergency conversion from sedation to general anesthesia and the need for cardiopulmonary resuscitation during the study period.1
Toyohashi Heart Center provided a sealed envelope with the treatment assignment, with patients allocated to receive either FIB (FIB group) or not (control group). The cardiologist opened the envelope once the patient had arrived in the operating room.
Treatment and Measurement During TAVI
None of the patients was administered premedication, with all prescribed medications, except angiotensin receptor antagonists and angiotensin-converting enzyme inhibitors, continued until the morning of TAVI. At Toyohashi Heart Center, patients undergoing transfemoral TAVI usually receive conscious sedation during the procedure. According to the American Society of Anesthesiologists,7 conscious sedation is defined a drug-induced depression of consciousness. Patients respond purposefully to verbal commands, either alone or by light tactile stimulation; no interventions are required to maintain a patent airway and spontaneous ventilation is adequate. The depth of sedation was monitored using bispectral analysis (BISTM; Covidien Japan Inc., Tokyo, Japan) throughout sedation and valve implantation. An anesthesiologist (H.K.) instructed the cardiologists (M.Y., Y.A., and R.Y.) on FIB, and each cardiologist completed at least 10 FIBs on patients before the study. Based on our previous experience, an approximate 2-min wait time after FIB combined with infiltration analgesia with 1% lidocaine helps reduce pain during transfemoral TAVI.8 Thus, this timeline and dose of local anesthetic were used in the present study.
Conscious sedation for each patient under 100% face mask oxygen supplementation (5 L/min) was initiated with 0.7 µg/kg, i.v., dexmedetomidine and subsequent infusion of 0.4 µg/kg/h, i.v., dexmedetomidine. This was supplemented with 0.03 µg/kg/min, i.v., remifentanil and 0.3 mg/kg/h, i.v., propofol to achieve a BIS <90 with a Richmond Agitation-Sedation Scale (RASS) of −2 to −1.9 Then, in patients in the FIB group, a cardiologist (M.Y., Y.A., or R.Y.) implemented the ultrasound-guided right or left FIB, depending on which side the expandable sheath was inserted. The preparation time for FIB was 3–5 min, including a pre-scan using ultrasound. For FIB, 2 min before commencement of TAVI, 30 mL of 0.185% ropivacaine was injected beneath the fascia iliaca via a 20-G Tuohy needle under local anesthesia with 2 mL of 1% lidocaine (Figure 1). All FIB procedures in the FIB group were completed within 5 min; in the control group, an equivalent 5-min wait time was implemented as a sham nerve block. The effect of FIB was confirmed at the end of TAVI as reduced cold sensation on the anterior surface of the thigh in response to an ice-cold normal saline plastic bottle. Indeed, FIB was judged to be effective when a patient complained of a cold sensation only on the thigh contralateral to the FIB side. In addition, in both groups, similar dressings for the block site and sham block site were applied, and infiltration analgesia with 1% lidocaine (15 or 13 mL in the control and FIB groups, respectively) was applied to the procedural regions before cardiologists, and an anesthesiologist in charge of TAVI, appeared. The cardiologist who performed the FIB did not participate in patient management and evaluation during and after TAVI. These procedures ensure that the cardiologists performing TAVI and the anesthesiologist in charge of TAVI were blinded as to the group to which the patient was assigned.
The level of sedation was maintained throughout the TAVI procedure by the anesthesiologist at a BIS target <90, with an RASS of −2 to −1. To maintain sedation, the anesthesiologist used 0.4 µg/kg/h, i.v., dexmedetomidine supplemented with 0–0.02 µg/kg/min, i.v., remifentanil. Patients were instructed to inform us if they experienced any pain during TAVI, so they could be administered a rescue regimen. When patients experienced pain during TAVI, they were administered 20 µg, i.v., remifentanil. Invasive arterial pressure monitoring was used, and a temporary pacemaker wire was inserted through the femoral vein for rapid ventricular pacing. Implantation was guided by fluoroscopy. The activated clotting time was prolonged to >300 s using heparin (100 U/kg, i.v.), and reversed to <150 s at the end of TAVI by the administration of protamine (0.8–0.85 mg/kg, i.v.). All patients received 0.01–0.07 µg/kg/min, i.v., norepinephrine and 0.05 mg, i.v., phenylephrine several times to maintain mean arterial pressure (MAP) >65 mmHg. Hemodynamic and sedation parameters were recorded at baseline, at the time of insertion of the expandable sheath, at 30 min, and at the end of TAVI. The frequency of patients’ experiences of pain and voluntary body movement at any time during TAVI were also evaluated. Arterial blood gas analysis was performed at 10 min and the end of TAVI.
Treatment and Measurement After TAVI
Cardiologists were responsible for postoperative intensive care. All patients received 0.4 µg/kg/h, i.v., dexmedetomidine in the intensive care unit until the following day. Nurses, blinded to the present study, evaluated patients’ hemodynamics, sedation (RASS), and pain (numerical rating scale [NSR] from 0 [no pain] to 10 [unbearable pain]) at 1, 3, and 6 h after TAVI. In addition, the need for post-TAVI pacing, vascular complications at the TAVI access site during admission, complications at the FIB site during admission, and the length of hospital stay were recorded.
Statistical Analysis
Statistical analyses were performed using IBM SPSSTM
Statistics ver. 27 (IBM Japan Inc., Tokyo, Japan). Continuous variables are presented as the median and interquartile (25–75th percentile) range and were compared between groups using the Mann-Whiney U test. Categorical variables are presented as the number of cases with percentages, and were compared between groups using the χ2
test. Differences were considered to be statistically significant at P<0.05.
Previous studies considered a 50% reduction in remifentanil as a clinically relevant dose difference,10 and so this was evaluated as the primary outcome in the present study. In the present study, a 36 µg difference in the total dose of remifentanil provided 95% power to detect a significant difference at a level of α=0.05 with a sample size of 20 (SD=30). The power calculation was done using G*power Version 3.1.9.6 (Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany).
Results
This study enrolled 79 patients scheduled for elective transfemoral TAVI under conscious sedation (Figure 2). Five patients were excluded because they did not meet the inclusion criteria; thus, the remaining 74 patients were randomized into the FIB group (n=37) and control group (n=37). One patient each in the FIB and control groups was further excluded because of the need for emergency conversion to general anesthesia. This conversion resulted from cardiopulmonary resuscitation and emergency intubation during TAVI. However, the outcomes for both patients were uneventful. Thus, 36 patients were finally included in each group (Supplementary Figure).
Patients’ preoperative characteristics were comparable between the control and FIB groups, except for the mean pressure gradient of the aortic valve and carotid stenosis (Table 1). In addition, there were no significant differences in prescribed anticoagulants and antiplatelet drugs, or in hemoglobin and platelet concentrations in the blood, preoperatively between the 2 groups (Table 2).
Table 1.
Patients’ Preoperative Characteristics
| |
Control
(n=36) |
FIB
(n=36) |
P value |
| Female sex |
26 (72.2) |
22 (61.6) |
0.454 |
| Age (years) |
84 [80–88] |
84 [80–87] |
0.777 |
| BMI (kg/m) |
22.8 [19.9–26.2] |
23.1 [19.4–25.5] |
0.978 |
| NYHA Class II/III (n) |
35/1 |
31/5 |
0.199 |
| Aortic valve area (cm2) |
0.70 [0.61–0.83] |
0.71 [0.57–0.94] |
0.727 |
| Pressure gradient at the aortic valve (mmHg) |
| Mean |
46 [39–57] |
40 [34–47] |
0.010 |
| Maximum |
83 [70–98] |
74 [68–83] |
0.053 |
| Prior aortic valve procedure |
2 (5.6) |
2 (5.6) |
1.000 |
| Left main trunk stenosis ≥50% |
0 (0) |
2 (5.6) |
0.493 |
| Proximal LAD stenosis ≥70% |
10 (27.8) |
3 (8.3) |
0.063 |
| Prior myocardial infarction |
1 (2.8) |
3 (8.3) |
0.614 |
| Prior PCI |
4 (11.1) |
5 (13.9) |
1.000 |
| Prior CABG |
0 (0) |
1 (2.8) |
1.000 |
| Moderate to severe AR |
8 (22.2) |
6 (16.7) |
0.551 |
| Moderate to severe MR |
5 (13.9) |
7 (19.4) |
0.527 |
| Moderate to severe TR |
2 (5.6) |
5 (13.9) |
0.429 |
| Atrial fibrillation |
7 (19.4) |
11 (30.6) |
0.415 |
| Prior pacemaker |
2 (5.6) |
0 (0) |
0.493 |
| Carotid stenosis |
6 (16.7) |
0 (0) |
0.025 |
| Prior stroke |
15 (41.7) |
9 (25) |
0.211 |
| Prior peripheral artery disease |
0 (0) |
2 (5.6) |
0.493 |
| Hemodialysis |
4 (11.1) |
7 (19.4) |
0.415 |
| COPD |
14 (38.9) |
16 (44.4) |
0.811 |
Unless indicated otherwise, data are given as the median [interquartile range] or n (%). AR, aortic valve regurgitation; BMI, body mass index; CABG, coronary artery bypass grafting; COPD, chronic obstructive pulmonary disease; FIB, fascia iliaca block; LAD, left anterior descending artery; MR, mitral valve regurgitation; NYHA, New York Heart Association; PCI, percutaneous coronary intervention; TR, tricuspid valve regurgitation.
Table 2.
Preoperatively Prescribed Anticoagulants, Antiplatelet Drugs, and Laboratory Data in the Studied Patients
| |
Control
(n=36) |
FIB
(n=36) |
P value |
| Medications |
| Aspirin |
7 (19.4) |
9 (25) |
0.571 |
| P2Y12 antagonist |
7 (19.4) |
6 (16.7) |
0.759 |
| Factor Xa antagonist |
7 (19.4) |
2 (5.6) |
0.151 |
| Warfarin |
2 (5.6) |
2 (5.6) |
1.000 |
| Thrombin antagonist |
0 (0) |
1 (1) |
1.000 |
| PDE3 antagonist |
1 (2.8) |
0 (0) |
1.000 |
| Eicosapentaenoic acid |
2 (5.6) |
0 (0) |
1.000 |
| Laboratory data |
| Hemoglobin (g/dL) |
11.8 [10.8–13.2] |
12.0 [10.8–12.9] |
0.969 |
| Platelets (×10,000/μL) |
17.3 [14.0–20.4] |
17.6 [14.1–23.1] |
0.532 |
Unless indicated otherwise, data are given as the median [interquartile range] or n (%). FIB, fascia iliaca block; PDE3, phosphodiesterase 3.
Procedure-related values are presented in Table 3. The duration of sedation, TAVI, the time from the start of TAVI to insertion of the expandable sheath, and the prosthesis type, including balloon-expandable (Sapien 3TM) and self-expanding (CoreValveTM) devices, were similar between the 2 groups. In contrast, FIB reduced the frequency of pain experienced by patients, as well as the total, median, and rescue doses of remifentanil during TAVI; however, FIB did not alter patients’ voluntary body movements (Table 3). The BIS, RASS, MAP, and heart rate (HR) values at the beginning of sedation, sheath insertion, at the TAVI 30-min mark, and at the end of TAVI did not differ between the control and FIB groups (Table 3). In addition, arterial pH, PaO2, PaCO2, and base excess at the TAVI 10-min mark and at the end of TAVI were similar between the 2 groups (Table 3). Percutaneous oxygen saturation in patients was maintained at >98% throughout TAVI. In addition, we confirmed reduced cold sensation on the anterior surface of the thigh at the end of TAVI in all patients in the FIB group.
Table 3.
Procedure-Related Values
| |
Control
(n=36) |
FIB
(n=36) |
P value |
| Duration of sedation (min) |
66 [53, 73] |
66 [56, 79] |
0.517 |
| Duration of TAVI (min) |
55 [42, 63] |
50 [44, 65] |
0.817 |
Time from start of TAVI to expandable sheath
insertion (min) |
14 [11, 18] |
15 [11, 18] |
0.928 |
| Prosthesis type: B-E/S-E (n) |
21/15 |
24/12 |
0.465 |
| Expression of pain: 0/1/2/3/4 times (n) |
0/12/17/3/4 |
31/4/1/0/0 |
<0.001 |
| Body movement: 0/1/2/3/4 times (n) |
0/12/17/3/4 |
21/8/5/1/1 |
0.076 |
| Remifentanil dose |
| Total (μg) |
83.0 [65.0, 98.0] |
34.5 [26.0, 45.8] |
<0.001 |
| Continuous infusion (ng/kg/min) |
25.3 [20.9, 31.5] |
9.5 [6.8, 12.5] |
<0.001 |
| Rescue remifentanil |
| Bolus infusion: 0/1/2/3/4 times (n) |
1/13/16/4/2 |
31/4/1/0/0 |
<0.001 |
| Dose (μg) |
40 [20, 40] |
0 [0, 0] |
<0.001 |
| BIS |
| At start of sedation |
96 [94, 98] |
96 [92, 98] |
0.927 |
| At sheath insertion |
87 [79, 93] |
83 [77, 94] |
0.550 |
| At TAVI 30-min mark |
83 [76, 91] |
83 [74, 90] |
0.796 |
| At end of TAVI |
90 [79, 94] |
89 [80, 97] |
0.946 |
| RASS |
| At start of sedation |
0 [−1, 0] |
0 [−1, 0] |
0.862 |
| At sheath insertion |
−1 [−1, −1] |
−1 [−1, −1] |
0.629 |
| At TAVI 30-min mark |
−1 [−1, −1] |
−1 [−1, −1] |
0.923 |
| At end of TAVI |
−1 [−1, −1] |
−1 [−1, −1] |
0.145 |
| MAP (mmHg) |
| At start of sedation |
104 [92, 123] |
110 [97, 120] |
0.673 |
| At sheath insertion |
85 [81, 102] |
89 [82, 100] |
0.735 |
| At TAVI 30-min mark |
94 [87, 105] |
92 [83, 103] |
0.314 |
| At end of TAVI |
79 [67, 96] |
84 [74, 91] |
0.376 |
| HR (beats/min) |
| At start of sedation |
72 [65, 77] |
70 [62, 79] |
0.795 |
| At sheath insertion |
59 [54, 69] |
63 [56, 72] |
0.211 |
| At TAVI 30-min mark |
64 [60, 75] |
64 [55, 74] |
0.553 |
| At end of TAVI |
68 [58, 77] |
64 [60, 71] |
0.436 |
| TAVI 10-min mark |
| pH |
7.39 [7.35, 7.41] |
7.38 [7.37, 7.40] |
0.569 |
| PaO2 (mmHg) |
249 [209, 306] |
255 [206, 297] |
0.866 |
| PaCO2 (mmHg) |
41 [39, 47] |
42 [39, 44] |
0.719 |
| BE |
0.0 [−1.2, 1.3] |
−0.5 [−1.2, 0.8] |
0.585 |
| End of TAVI |
| pH |
7.36 [7.34, 7.40] |
7.37 [7.36, 7.39] |
0.397 |
| PaO2 (mmHg) |
168 [135, 246] |
175 [127, 253] |
0.909 |
| PaCO2 (mmHg) |
42 [40, 45] |
41 [39, 43] |
0.312 |
| BE |
−0.5 [−2.4, 0.5] |
−1.0 [−2.5, 0.1] |
0.986 |
Unless indicated otherwise, data are given as the median [interquartile range]. BE, base excess; B-E, balloon-expandable; BIS, bispectral index; FIB, fascia iliaca block; HR, heart rate; MAP, mean arterial pressure; RASS, Richmond Agitation-Sedation Scale; S-E, self-expandable; TAVI, transcatheter aortic valve implantation.
Pain up to 6 h after TAVI was mostly undetected in both groups, and RASS, MAP, and HR values were similar, except for HR values 3 h after TAVI (Table 4). The frequency of delirium until 24 h after TAVI, post-TAVI pacing, vascular access site complications during admission, and the length of hospital stay did not differ between the 2 groups (Table 4). We did not observe any FIB-site complications or pneumonia during hospitalization in the studied patients.
Table 4.
Postprocedure Values
| |
Control
(n=36) |
FIB
(n=36) |
P value |
| Pain intensity (NRS) |
| 1 h after TAVI |
0 [0, 1] |
0 [0, 2] |
0.337 |
| 3 h after TAVI |
0 [0, 0] |
0 [0, 0] |
0.552 |
| 6 h after TAVI |
0 [0, 0] |
0 [0, 0] |
0.775 |
| RASS |
| 1 h after TAVI |
−2 [−3, −1] |
−1 [−2, 0] |
0.218 |
| 3 h after TAVI |
−1 [−3, −1] |
−1 [−2, −1] |
0.771 |
| 6 h after TAVI |
−1 [−2, 0] |
−1 [−2, 0] |
0.958 |
| MAP (mmHg) |
| 1 h after TAVI |
72 [63, 82] |
75 [67, 87] |
0.302 |
| 3 h after TAVI |
74 [68, 82] |
76 [66, 89] |
0.401 |
| 6 h after TAVI |
74 [68, 85] |
80 [67, 96] |
0.581 |
| HR (beats/min) |
| 1 h after TAVI |
57 [51, 63] |
59 [53, 72] |
0.250 |
| 3 h after TAVI |
54 [48, 61] |
61 [54, 72] |
0.012 |
| 6 h after TAVI |
61 [54, 68] |
64 [54, 76] |
0.243 |
| Delirium up to 24 h after TAVI |
3 (8.3) |
3 (8.3) |
1.000 |
| Post-TAVI pacing |
2 (5.6) |
3 (8.3) |
1.000 |
| Access site vascular complications |
1 (2.8) |
1 (2.8) |
1.000 |
| FIB site complications |
NA |
0 (0) |
NA |
| Length of stay (days) |
7 [6, 11] |
7 [6, 9] |
0.911 |
Unless indicated otherwise, data are given as the median [interquartile range] or n (%). NA, not applicable; NRS, numerical rating scale (0 [no pain] to 10 [unbearable pain]). Other abbreviations as in Tables 1,3.
Discussion
FIB significantly reduced the total, median, and rescue doses of remifentanil, as well as the frequency of pain experienced during TAVI. In addition, the decrease in remifentanil consumption was >50% in the FIB compared with control group, indicating that the reduction in opioid use resulting from the nerve block was clinically meaningful.10 Furthermore, FIB affects several nerves simultaneously, including the lateral femoral cutaneous, obturator, and femoral nerves.6 This suggests that FIB would be superior to sole femoral nerve block for pain relief during transfemoral TAVI, even though both techniques appear similar. More importantly, FIB, but not femoral nerve block, occurs at a sufficient distance from important inguinal neurovascular structures, supporting its safe use in acute hip fracture pain management.6,11 Accordingly, FIB appears safer than femoral nerve block in patients receiving antithrombotic therapy (heparin, i.v.) during TAVI. Indeed, there were no bleeding complications at the FIB site in the patients in the present study, although 2 patients had vascular access site complications during admission. In addition, previous studies showed that most surgical patients receiving anticoagulants and antiplatelet drugs do not appear to experience bleeding complications at the nerve block site, even in those undergoing somewhat invasive procedures, such as femoral perineural catheter insertion.12 However, more extensive studies are needed to verify the safety of FIB, including block site complications, in patients undergoing transfemoral TAVI.
During conscious sedation, patients’ RASS values were maintained at −2 to −1, where −1 indicates a “drowsy” condition, in which the patient is not fully alert but has sustained (more than 10 s) awakening, with eye contact in response to voice, and −2 suggests “light sedation”, where the patient briefly (<10 s) awakens with eye contact in response to voice.9 The results of the present study, combined with the RASS definition, support the conclusion that the patients in this study received appropriate conscious sedation. Previous studies have demonstrated that the RASS has high reliability and validity in medical and surgical, ventilated and non-ventilated, and sedated and non-sedated adult patients admitted to an intensive care unit.9 It is also critical to note that, in the present study, arterial carbon dioxide levels at the 10-min mark and end of TAVI were similar in the FIB and control groups. In addition, percutaneous oxygen saturation was maintained at 98% throughout transfemoral TAVI in all patients. Therefore, we can argue that definition of conscious sedation applies in the present study, in that no interventions were required to maintain a patent airway and spontaneous ventilation was adequate.7 BIS values at the beginning of sedation, sheath insertion, and at the 30-min mark and end of TAVI also did not differ between the control and FIB groups, strengthening our conclusion that sedation levels in both groups were similar. The BIS monitoring’s dimensionless numbers are not specific to amnesia induced by anesthetic agents because the values encompass several biological brain states.13 Thus, the BIS value is sensitive to all uncomfortable procedures without specificity, including those resulting from pain and noise.14 Furthermore, FIB did not reduce patients’ voluntary body movement, although it significantly reduced pain and the doses of remifentanil required. These results indicate that procedural pain and other uncomfortable stimuli played roles in similar sedation levels between the 2 groups. However, BIS monitoring can be used in the intensive care unit to avoid awareness because it is still advisable to maintain certain levels of sedation in patients.13
In the present study, the MAP and HR values at the beginning of sedation, sheath insertion, and at the 30-min mark and end of TAVI did not differ between the control and FIB groups. In addition, MAP and HR values were similar in the 2 groups, except for HR values 3 h after TAVI. These results indicate that the additional FIB technique for conscious sedation does not considerably alter hemodynamics during and after TAVI. That is, the dose of local anesthetic used in the present study for FIB did not affect patients’ hemodynamics during and after transfemoral TAVI, indicating its safety.
Previous studies documented that a sedation technique is possible for patients with aortic stenosis undergoing transfemoral TAVI.1–3 Recent research has documented several advantages of conscious sedation, compared with general anesthesia, in those undergoing TAVI.2,3 For example, a study demonstrated a briefer length of stay and lower in-hospital and 30-day mortality in patients undergoing conscious sedation.2 In contrast, another study showed similar outcomes for a composite of all-cause mortality, stroke, myocardial infarction, infection requiring antibiotic treatment, and acute kidney injury at the 30-day follow-up for patients who had undergone conscious sedation vs. general anesthesia.3 These results suggest the safety of conscious sedation in patients undergoing transfemoral TAVI. However, comparative effectiveness analyses using observational data cannot definitively establish the superiority of one technique over another.
The present study has some limitations. First, we used only a single timeline with 1 dose of local anesthetic for FIB implementation, based on considerations of preliminary cases.8 As a result, it took approximately 15 min from the start of TAVI until the insertion of an expandable sheath, compared with minutes after FIB until the start of TAVI. Most patients assigned to the control, but not FIB, group complained of significant pain upon insertion of the expandable sheath. Therefore, the timeline after FIB in the present study appears necessary for pain relief during expandable sheath insertion during transfemoral TAVI. Second, we did not examine long-term outcomes in the study patients, but all patients exhibited similar uncomplicated results, at least during admission for TAVI. More extensive studies are required to overcome the limitations of the present study.
Conclusions
The present prospective study is the first to demonstrate that FIB resulted in clinically meaningful reductions in opioid requirement and pain relief in patients undergoing transfemoral TAVI under conscious sedation. Therefore, FIB appears to improve the quality of conscious sedation in patients undergoing TAVI.
Acknowledgments
The authors thank Toyohashi Heart Centre for preparing the sealed envelopes with treatment assignment allocation for all patients.
Sources of Funding
This study did not receive any specific funding.
Disclosures
The authors have no conflicts of interest to declare.
IRB Information
This study was approved by the Ethics Committee of Toyohashi Heart Center (Reference no. 210105).
Data Availability
The deidentified participant data will not be shared.
Supplementary Files
Please find supplementary file(s);
https://doi.org/10.1253/circj.CJ-22-0580
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