REGIONAL ANAESTHESIA Comparison of economical aspects of interscalene brachial plexus blockade and general anaesthesia for arthroscopic shoulder surgery C. Gonano, S. C. Kettner, M. Ernstbrunner, K. Schebesta, A. Chiari and P. Marhofer* Department of Anaesthesia, Intensive Care Medicine and Pain Control, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria *Corresponding author. E-mail: peter.marhofer@meduniwien.ac.at Background. This study investigated the cost-effectiveness of ultrasonographic-guided interscalene brachial plexus blockade (ISB) in comparison with general anaesthesia (GA) for arthroscopic shoulder surgery. Methods. Forty patients undergoing arthroscopic shoulder surgery received either an ultrasonographic-guided ISB or GA. ISB was performed outside the operation room (OR) and patients were transferred in the OR at the earliest 20 min after block performance. All drugs and disposables were recorded to evaluate the costs for both techniques. The following anaesthesia-related times were defined: ready for surgical preparation (from arrival in the OR until end of anaesthesia induction), OR emergence time (from end of dressing until leaving the OR), anaesthesia control time (from patient s arrival in the OR until readiness for positioning plus time from the end of surgery to patient s discharge from the OR), and post-anaesthesia care unit (PACU) time (from patient s arrival in the PACU to the eligibility for discharge to normal ward). Personnel costs were excluded from statistical analysis. Results. The total costs were [mean (SD)] 33 (9)E for patients with ISB and 41 (7)E for those who received GA (P,0.01). The anaesthesia-related workflow was improved in the ISB group when compared with the GA group [ready for surgical preparation 8 (3) vs 13 (5) min, P,0.001; OR emergence time 4 (3) vs 10 (5), P,0.001; anaesthesia control time 12 (4) vs 23 (6), P,0.001; and PACU time 45 (17) vs 70 (20), P,0.001]. Conclusions. Ultrasonographic-guided ISB is a cost-effective method for arthroscopic shoulder surgery. Br J Anaesth 2009; 103: 428 33 British Journal of Anaesthesia 103 (3): 428 33 (2009) doi:10.1093/bja/aep173 Advance Access publication July 8, 2009 Keywords: anaesthesia, general; anaesthetic techniques, regional, brachial plexus; economics, medical; efficiency, organizational Accepted for publication: May 7, 2009 Both general anaesthesia (GA) and interscalene brachial plexus blockade (ISB) are effective anaesthesia methods for shoulder surgery. Possible advantages of regional compared with general techniques are lower postoperative pain levels and a reduced length of stay (LOS) in the postanaesthesia care unit (PACU). Little is known about the economical aspects of regional anaesthetic techniques compared with GA in the perioperative period. Recently, we described improved costeffectiveness of spinal vs GA in orthopaedic surgery. 1 In contrast, Chan and colleagues 2 found similar cost for transarterial axillary brachial plexus blockade compared with GA in patients undergoing hand surgery, which was mainly due to the long procedure times for regional anaesthesia. During the last few years, ultrasonographic guidance has become a widely used guidance technique for regional anaesthesia, with swifter procedure and faster onset times. 3 Therefore, ultrasonographic guidance may reduce procedure times for regional techniques and thereby # The Author [2009]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournal.org
Cost-effectiveness of ISB influence cost-effectiveness. Other aspects, such as decreased LOS in PACU or reduced demand of postoperative analgesics, may increase cost-effectiveness of regional techniques, but are not sufficiently investigated. 45 The present study was designed to evaluate potential economical advantages of ultrasonographic-guided ISB vs GA for arthroscopic shoulder surgery. Methods After obtaining Ethics Committee approval and written informed consent, 40 patients, ASA I III, undergoing elective arthroscopic shoulder surgery were enrolled in this study. Exclusion criteria were ASA.III, history of allergy to anaesthetic drugs, renal or liver disease, history of abuse of alcohol or narcotic substances, diseases of the central nervous system, or severe obstructive or restrictive pulmonary disease. Patients were randomized using the sealed envelope technique to receive either GA or ISB. During the preoperative application of standard monitoring (ECG, noninvasive arterial pressure, and pulse oximetry), an infusion of 500 ml of lactated Ringer s solution was initiated in both groups followed by a continuous infusion of 5mlkg 21 h 21 until the end of surgery. Before the ISB, patients received midazolam 0.05 mg kg 21. ISB was performed as previously described by Kapral and colleagues 6 using ultrasonographic guidance with a portable ultrasound device, a 5 10 MHz linear ultrasound probe (SonoSite Titan TM ; SonoSite Inc., Bothell, WA, USA), a 22 G 50 mm facette tip needle (Polymedic TM by tenema, Z.I. des Amandiers, France), and 20 ml of ropivacaine 7.5 mg ml 21. All blocks were performed in the preoperative area under sterile conditions by anaesthesia residents experienced in ultrasonographic-guided ISB with assistance of a nurse. Patients were transferred in the operation room (OR) at the earliest 20 min after performance of the blocks, which is based on the known range of sensory onset time of ultrasonographic-guided ISB with ropivacaine 0.75% between 6 and 13 min. 6 During this time, an independent observer assessed the sensory onset time of the ISB by pinprick testing (100% normal sensation, 0% no sensation). From positioning until end of surgery, each patient received propofol 3 5 mg kg 21 h 21 infusion for conscious sedation and oxygen 4 litre min 21 via a face mask. After application of the dressings, patients were immediately transferred to the PACU. Failure of ISB was defined as the inability to provide surgical anaesthesia requiring the use of GA. Patients requiring GA were not excluded from analysis according to an intention-to-treat approach. After 24 h, the site of injection of the ISB was controlled to detect side-effects such as haematomas or infection. In the GA group, anaesthesia was induced with midazolam 0.05 mg kg 21, fentanyl 3 mg kg 21, propofol 4mgkg 21, and rocuronium 0.3 mg kg 21. Subsequently, the trachea was intubated and GA was continued with 1 MAC sevoflurane in air/o 2 (FI O2 30%) and 1.5 litre min 21 fresh gas flow. Mechanical ventilation was performed in a pressure-controlled mode to maintain E 0 CO 2 between 4.6 and 5.3 kpa. Fentanyl boluses 1.5 mg kg 21 were administered at the discretion of the responsible anaesthetist. At the beginning of the skin closure, anaesthesia was discontinued and tracheal extubation was performed once the patient was awake. All patients were operated in beach chair position. Intraoperative bradycardia (HR,50 beats min 21 ) was treated with atropine 0.5 mg, and hypotension (decrease of MAP.30% from baseline) was treated with additional bolus administration of lactated Ringer s solution 3mlkg 21 and bolus application of etilefrine as appropriate. Intraoperatively, all patients received acetaminophen 1 g i.v. Postoperative analgesia was standardized with boluses of piritramid 3 mg i.v. to achieve analgesia visual analogue scale (VAS) scores of 3. In cases of postoperative nausea and vomiting, patients received ondansetron 8 mg. After operation, patients were transferred to the PACU for a minimum of 30 min. Immediately after admission to PACU and every 10 min, an independent observer assessed the haemodynamic status, the pain profile, and the recovery score. Patients fulfilled discharge criteria as soon as they had a modified Aldrete score of 9 or more and required no treatment for pain (VAS 3) or nausea and vomiting. The main outcome parameter of this study was the economic impact of the two anaesthesia methods (GA vs ISB). Therefore, the use of drugs and disposables was recorded. Anaesthetic drug cost was obtained from our pharmacy department (Table 1) and calculated using the assumption that the residual drug remaining in a single-use Table 1 Cost for drugs and disposables (in Euros) Drugs and disposables Midazolam 5 mg 0.10 Fentanyl 0.5 mg 0.80 Propofol 200 mg 0.90 Propofol 500 mg 2.50 Rocuronium 50 mg 5.40 Sevoflurane 250 ml 140.40 Ropivacaine 7.5 mg ml 21 20 ml 7.40 Sterile ultrasound jelly 0.70 Ultrasound probe cover 3.50 Nerve block needle (22 G) 5.90 Tube, PAL filter, extension 5.00 Oxygen mask 0.50 Acetaminophen 1 g 1.37 Piritramid 15 mg 0.60 Ondansetron 8 mg 0.59 Etilefrine 10 mg 0.90 Atropine 0.5 mg 0.15 Fluid 1000 ml 1.78 E 429
Gonano et al. ampoule had to be discarded. The cost of sevoflurane was calculated using the formula published by Dion and colleagues. 7 If GA was required supplemental to ISB, the cost of all additional drugs and disposables was added to the cost of the ISB group. Personnel costs were excluded from the economical statistical analysis. The following time points were defined: (i) ISB time: from sterile preparation of the skin until withdrawing of the needle; (ii) ISB onset time: time from administration of the local anaesthetic until pinprick 0 (no sensation); (iii) Ready for surgical preparation: time from arrival in the OR until end of anaesthesia induction; (iv) Surgical time: from incision to skin closure; (v) OR emergence time: from end of dressing until leaving the OR; (vi) Anaesthesia control time: from patient s arrival in the OR until readiness for positioning plus time from the end of surgery to patient s discharge from the OR; (vii) Total anaesthesia time: ISB plus anaesthesia control time; (viii) PACU time: from patient s arrival in the PACU to the eligibility for discharge to normal ward. Sample size estimates were based on total anaesthesia costs in Euros (E) for providing ISB or GA in patients undergoing shoulder surgery. It was estimated that a sample size of 14 per group would provide 80% power to detect a clinically meaningful difference of 25% (10E, within-group SD, 10E) at an a of 0.05. The sample size was increased to 20 per group, resulting in a power of 90% at an a of 0.05. Data were analysed with SPSS version 16.0.2 for Mac software (SPSS Inc., Chicago, IL, USA). Costs, time interval, age, height, and weight were analysed with the independent Student s t-test, categorical data were analysed using x 2 or Fisher s exact test as appropriate, and ordinal data were analysed using the Mann Whitney test. P,0.05 was considered as significant. Results A flow chart (Fig. 1) according to the CONSORT statement illustrates the patients selection process. Patient characteristic data are presented in Table 2. One patient in the ISB group required GA due to failure of the ISB. Total costs per case were [mean (SD)] 33 (9)E in the ISB group compared with 41 (7)E in the GA group (P,0.001). Accordingly, costs per minute of anaesthesia during surgery were also lower in the ISB group compared with the GA group [0.37 (0.12) vs 0.55 (0.17)E, P,0.001]. Table 3 presents the anaesthesia method-related sideeffects and the PACU-specific data. The total anaesthesia time was comparable in both groups. The total times for ISB cases (performance of the block plus anaesthesia control time) were similar to those for GA (induction time for GA plus anaesthesia control time plus recovery) (Table 4). The postoperative pain scores and piritramid consumption were lower (Table 3) and the PACU time was shorter in the ISB group (Table 4). Only the one patient with a block failure in the ISB group required postoperative piritramid, whereas 18 out of 20 patients in the GA group required postoperative piritramid. No anaesthesia or surgery-related complications were detected. In one patient (5%), we observed a Horner syndrome, which was unverifiable after 24 h. Assessed for eligibility and randomized (n=40) ISB group (n=20) GA group (n=20) Block success: 19 patients (ISB) Block failure: 1 patient (ISB and GA) Evaluation of costs GA group (n=20) Evaluation of costs ISB group (n=20) Fig 1 Patient s selection process according to the CONSORT statement. ISB group, interscalene group; GA group, general anaesthesia group. 430
Cost-effectiveness of ISB Table 2 Pertinent characteristics. ISB group, interscalene group; GA group, general anaesthesia group. Data are presented as mean (range), (SD) or ratio Table 3 Anaesthesia-related side-effects. ISB group, interscalene group; GA group, general anaesthesia group. Data are presented as mean (range) or percentage Discussion ISB group GA group n 20 20 Age (yr) 59 (35 73) 54 (34 69) Sex (M/F) 11/9 9/11 Height (cm) 166 (8) 170 (12) Weight (kg) 76 (14) 77 (18) ASA I/II/III 6/12/2 6/11/3 Co-morbidities (n) 1 (0 2) 1 (0 2) ISB group GA group P-value Block failure 1 Phrenic nerve block 0 Horner syndrome 1 Hypotension (n; %) 2; 10 12; 60,0.001 Etilefrine (mg) 0 (0 3) 2 (0 12),0.01 Aldrete score admission 9 (8 10) 8 (6 10),0.05 Pain VAS PACU 0 (0 4) 6 (0 10),0.001 Piritramid (mg) 0 (0 6) 9 (0 15),0.001 Nausea and vomiting (n) 0 2 NS Table 4 Economical aspects and time analysis. ISB group, interscalene group; GA group, general anaesthesia group. Data are presented as mean (SD). ISB time: from sterile preparation of the skin until withdrawing of the needle; Sensory onset time of ISB: time from administration of the local anaesthetic until pinprick 0; Ready for surgical preparation: time from arrival in the OR until end of anaesthesia induction; Surgical time: from incision to skin closure; OR emergence time: from end of dressing until leaving the OR; Anaesthesia control time: from patient s arrival in the OR until readiness for positioning plus time from the end of surgery to patient s discharge from the OR; Total anaesthesia time: ISB time plus anaesthesia control time; PACU time: from patient s arrival in the PACU to the eligibility for discharge to normal ward ISB group GA group P-value Direct monetary aspects Total costs (E) 33 (9) 41 (7),0.01 Proportionate PACU costs (E) 0.3 (0.5) 1.5 (0.6),0.01 Costs per minute (E min 21 ) 0.37 (0.12) 0.55 (0.17),0.001 Indirect monetary aspects (time analysis) ISB time (min) 11 (7) Sensory onset time of ISB (min) 7 (3) Ready for surgical preparation (min) 8 (3) 13 (5),0.001 Surgical time (min) 82 (23) 82 (34) NS OR emergence time (min) 4 (3) 10 (5),0.001 Anaesthesia control time (min) 12 (4) 23 (6),0.001 Total anaesthesia time (min) 22 (8) 23 (6) NS PACU time (min) 45 (17) 70 (20),0.001 This study shows that ISB is a cost-effective anaesthetic method for arthroscopic shoulder surgery. ISB results in reduced costs for drugs and supplies, decreased anaesthesia control time, and a shorter LOS in PACU compared with GA. Although the fixed costs were lower in the ISB group, the difference of 8E per case is of limited economical relevance, compared with overall OR costs. Therefore, the analysis of anaesthesia-related workflow is more important to determine cost-effectiveness of anaesthetic techniques than the analysis of drug and supply costs. With the ISB performed in the OR, costs would have been comparable, as the ISB time of 11 min was similar to the time for induction and emergence of GA. However, the anaesthesia control time was almost halved from 23 min in the GA group to 12 min in the ISB group, which is an opportunity to optimize OR utilization. When the ISB is performed in a separate induction room, the patient can enter the OR as soon as it is available, thereby decreasing turnover times and increasing OR utilization. Staff and OR costs vary largely between different hospitals due to different terms of employment, staff requirements, and clinical profile. We did not include costs for staff in the economical statistical analysis due to assumed large differences in personnel costs and medical systems, but a hypothetical calculation of costs, where personnel costs are included, may clarify the economical advantages of ultrasonographic-guided ISB for arthroscopic shoulder surgery. Stahl and colleagues 8 report 15 USD (12E) OR costs per minute, and calculations in our institution (Medical University of Vienna) are based on 14.89 E min 21 (Table 5). A reduction of the anaesthesia control time of 11 min results, therefore, in a cost reduction of 163.79E per case and 171.79E per case if the reduction of 8E fixed costs is added. However, the anaesthesia workflow has to be adapted to perform the block in a separate induction room and in advance of the scheduled surgery. Anaesthesia-related workflow is mainly based on two factors: the optimization in sequence of work and the individual anaesthesia technique. In the recent study, we performed ultrasonographic-guided ISB. The main advantages of ultrasonographic guidance for regional anaesthesia are faster performance of blocks, faster onset times, longer duration of blocks, and higher success rates. 6 9 Previous studies in this field used conventional guidance techniques, and described, therefore, substantial longer times for performance and onset of blocks. 210 The utilization of cost reductions by regional anaesthesia depends on fast performance of blocks, which can be facilitated by ultrasound guidance. 11 Higher success rates of ultrasonographic-guided regional blocks are another important cost factor. Kapral and colleagues 6 described a success rate of 99% for ultrasonographic-guided ISB compared with 91% for nerve stimulator-guided ISB. In our study, which was not designed to describe ISB success rates, one out of 20 patients (5%) required GA. The costs for the failed block were 55E (ISB plus additional GA), which is equivalent with additional costs of 22E per failed block. A failure rate of 20% is described for a number of regional techniques using conventional guidance techniques in the literature. 12 A failure rate of 20% would 431
Gonano et al. Table 5 Summary of costs per minute for one OR at the Medical University of Vienna. The total costs are 14.89E. *Costs for 1 min GA. 1 Costs for installation of surgical and anaesthesia equipment, respirator, monitoring, X-ray, electric cauter, etc. Information technology, administration, laundry, accounting, billing, maintenance, safety, procurement, and storage costs. } Includes cleaning and energy costs Number E min 21 Amount E min 21 Integrated total E min 21 Staff Anaesthetist 1.5 1.14 1.71 Orthopaedic surgeon 2 1.14 2.28 OR and anaesthesia nurses 2.5 0.57 1.35 X-ray technician 0.5 0.57 0.285 Lab technician 0.5 0.57 0.285 5.91 Anaesthesia-related material costs * 1 0.60 0.60 0.60 Installation costs (100 000E for surgery and anaesthesia) 1.64 1.64 Overhead costs 6.40 6.40 Occupancy costs } OR 50 m 2 0.0049 0.245 Induction room 20 m 2 0.0049 0.098 0.34 eliminate most of the cost reduction of ISB, as failed blocks also increase anaesthesia relevant times. Other cost-reducing factors in our study are the reduced PACU time, demand on postoperative systemic pain therapy, and therapy for nausea and vomiting in patients undergoing shoulder surgery with ISB. This finding may be a significant cost factor, but depends on the case load of the PACU. Dexter and colleagues 13 showed that a reduced LOS in PACU does not necessarily reduce PACU costs, as the PACU costs predominantly depend on peak PACU patient number and not on average patient number. Therefore, it is unclear whether a reduced LOS in PACU results in any cost reduction. Only 10% of patients in the ISB group vs 60% in the GA group needed vasopressor therapy during the surgical procedure. Thus, less fluids and vasopressor drugs are required when regional anaesthesia is used for shoulder surgery in the sitting position. This is only a minor cost factor, but may be a marker for an increase in patient s safety. The cost reduction of ultrasonographic-guided ISB during shoulder surgery is significant. Nevertheless, the underlying prerequisites should be also considered. Ultrasound equipment and training in ultrasonographicguided blocks are associated with a significant investment. Both cost factors are not calculated in this analysis because of too many variables. Ultrasound equipment can be used for several purposes and shared with other users. By an optimal utilization of the equipment, a fast amortization of the initial investment can be assumed. Costs for education and training are also very difficult to calculate. Learning curves are highly individual, and it is still the case that no standardized and generally accepted guidelines for education are available. A possible significant cost factor could be differences between in- and outpatients, which is not investigated in the current study. The Austrian health and insurance system strongly supports an inpatient system, which makes an investigation regarding cost analysis with an adequate power to identify the number of unexpected hospital admission after surgery difficult. Future studies should be designed to evaluate the cost-effectiveness of GA vs regional anaesthesia in an outpatient system. We conclude that ultrasonographic-guided ISB is a costeffective anaesthesia method for arthroscopic shoulder surgery. Compared with GA, ISB is associated with less total anaesthesia-related costs and an improved time efficacy. Prerequisites for the realization of the costeffectiveness are high success rates for ISB and an optimal anaesthesia-related workflow. References 1 Gonano C, Leitgeb U, Sitzwohl C, Ihra G, Weinstabl C, Kettner SC. Spinal versus general anesthesia for orthopedic surgery: anesthesia drug and supply costs. Anesth Analg 2006; 102: 524 9 2 Chan VWS, Peng PWH, Kaszas Z, et al. 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