Evidence Report/Technology Assessment: Number 16
Anesthesia Management During Cataract Surgery
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Under its Evidence-based Practice Program, the Agency for Healthcare Research and Quality (AHRQ) is developing scientific information for other agencies and organizations on which to base clinical guidelines, performance measures, and other quality improvement tools. Contractor institutions review all relevant scientific literature on assigned clinical care topics and produce evidence reports and technology assessments, conduct research on methodologies and the effectiveness of their implementation, and participate in technical assistance activities.
Overview / Reporting the Evidence / Methodology / Findings / Future Research / Availability of the Full Report
Surgery for age-related cataract is the highest volume surgical procedure performed on Medicare beneficiaries. Approximately 1.5 million surgeries were performed on this population in 1996. Cataract surgery is performed almost exclusively as an outpatient procedure. It usually involves the administration of a local anesthetic in addition to systemic sedation administered by an anesthesiologist or nurse anesthetist.
Previous research has indicated substantial national and international variation in anesthesia management strategies for cataract surgery. The most common forms of local anesthesia include injection techniques (retrobulbar, peribulbar, subconjunctival/sub-Tenon's) and topical anesthesia. Sedating agents given orally or intravenously are commonly used to reduce patient anxiety and discomfort.
Surgeons' and anesthesiologists' preferences, as well as patient characteristics, are believed to influence the choice of anesthesia management for cataract surgery. However, there is uncertainty as to which strategy or strategies provide the best mix of patient comfort, surgical outcomes (e.g., pain control, ease of performing surgery), and freedom from anesthesia-related complications (e.g., brainstem anesthesia, retrobulbar hemorrhage, globe perforation). Therefore, in October 1998, the Agency for Health Care Policy and Research, now renamed the Agency for Healthcare Research and Quality (AHRQ), awarded a contract to the Johns Hopkins University Evidence-based Practice Center to prepare an evidence report on the management of local anesthesia and sedation during surgery for age-related cataract.
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Reporting the Evidence
The principal objective of this evidence report is to summarize the published literature on the risks and benefits associated with the use of one form of regional anesthesia over another and the risks and benefits associated with different approaches to sedating the patient for cataract surgery.
Two key questions were addressed in the literature abstraction process:
- What are the risks and benefits associated with the use of one form of regional anesthesia over another?
- What are the risks and benefits associated with different approaches to sedating the patient for cataract surgery?
For the first question, published studies comparing common forms of local anesthesia, including injection techniques and topical anesthesia, were reviewed. This question included issues related to patient characteristics, complications, choice of agent, training, and evidence for supplemental agents to enhance local anesthesia performance (e.g., heat and pH adjustment). The second question included issues related to complication rates, specific sedation strategies, level and intensity of monitoring, and the presence of evidence supporting the use of sedation.
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An article was included in the evidence report if it:
- Addressed cataract surgery using local anesthesia (with or without sedation) in an adult population.
- Was a controlled trial or a case series with more than 100 cases.
- Provided outcomes specifically related to the research questions described above.
In addition to data collected on risks and benefits, further information of interest included:
- Setting of surgery.
- Intraoperative monitoring.
- Patient comorbidity.
- Choice of agent.
- Prior training of personnel.
- Use of supplemental agents.
The specific questions addressed in the evidence report were identified through consultation by the study team with a core panel of clinical experts. Electronic searches were conducted in PubMed and CENTRAL, the Cochrane Collaboration's database of controlled trials. PubMed includes publications from 1966 to the present. CENTRAL includes controlled trials from 1948 to the present. Additionally, principal ophthalmology- and anesthesiology-related journals, as well as reference lists from major reviews, were hand searched. The medical subject heading (MeSH) terms used in the searches included cataract, anesthesia, hypnotics, and sedatives. The literature considered was not limited to randomized trials but also included nonrandomized controlled trials and case series of 100 or more patients.
Of 1,857 potentially relevant citations identified, 739 were unique, appeared to meet the inclusion criteria, and were subsequently included in the abstract review process. All included studies were published between 1968 and 1999. After full review of abstracts and available published studies, 141 articles were identified that met all the eligibility criteria. Pairs of reviewers assessed study quality and abstracted data.
The results are presented in evidence tables, where the quality of evidence for specific questions is graded as strong, moderate, weak, or insufficient. The report also includes supplemental analyses:
- An analysis of early postoperative morbidity and mortality based on Medicare claims data.
- A decision analysis comparing alternative management strategies.
- An analysis of patient perceptions of different anesthesia strategies from the Study of Medical Testing for Cataract Surgery.
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Of the 141 studies reviewed, 122 focused on either local anesthesia techniques or local techniques in combination with sedation strategies. Of these, 86 were randomized clinical trials and 36 were noncontrolled studies including 100 or more patients. Nineteen studies, all of which were randomized clinical trials, specifically focused on issues related to sedation. The mean overall methodology quality score (maximum = 100) was 46 for randomized clinical trials and 33 for noncontrolled studies. There were significant issues in all quality domains examined. However, the lowest scores were in the areas of study representativeness, issues relating to methodologic bias, and adequacy of the description of therapy.
Globe Akinesia (Control of Ocular Movement)
There was strong evidence that indicated no difference between peribulbar and retrobulbar anesthesia in achieving globe akinesia for cataract surgery. There was insufficient evidence to compare subconjunctival/sub-Tenon's anesthetic block with peribulbar and retrobulbar blocks. However, the rates of adequate akinesia appeared to be similar across the three techniques. There was weak evidence that adding hyaluronidase or using specific anesthetic agents instead of others produced superior akinesia. There was insufficient evidence to reach any conclusion regarding the relationship of block effectiveness to volume of anesthetic used or speed of injection.
Pain of Administration of Block
There was weak evidence to suggest that peribulbar injection was slightly less painful than retrobulbar injection, moderate evidence that subconjunctival/sub-Tenon's block was less painful than retrobulbar block, and insufficient evidence that subconjunctival/sub-Tenon's block was slightly less painful than peribulbar block.
Pain Control During Cataract Surgery
All of the major classes of techniques reported yielded good or excellent intraoperative pain control. The evidence was strong that retrobulbar and peribulbar techniques produce equivalent pain control during cataract surgery, and there was moderate evidence indicating superior pain control with the use of subconjunctival/sub-Tenon's approaches compared with retrobulbar block. There was insufficient evidence to determine whether peribulbar or subconjunctival/sub-Tenon's anesthesia results in better pain control during surgery. There was strong evidence that retrobulbar block results in less pain during cataract surgery than topical anesthesia, moderate evidence that peribulbar block results in less pain during cataract surgery than topical anesthesia, and weak evidence that subconjunctival/sub-Tenon's block results in less pain during cataract surgery than topical anesthesia.
Specific Agents Used for Local Anesthesia
Virtually all agents reported had high rates of excellent pain control. There was insufficient evidence to determine whether some agents produced better pain control during surgery than others.
Complications related to different anesthesia techniques were rarely and not systematically reported in the literature. The most important ocular and systemic complications (e.g., globe perforation, myocardial infarction) are sufficiently rare that the reported frequency was almost invariably zero. Comparison of complication rates was also limited by wide variation in outcome definitions.
Weak evidence was found that intravenous or intramuscular sedation or analgesia is associated with better anxiety control, pain relief, and patient satisfaction than the lack of such sedation or analgesia. There was insufficient evidence to suggest that one analgesic regimen was superior to another.
Three supplemental analyses were performed:
- Analysis of a large Medicare claims data set—This analysis was directed toward ascertaining risk factors for readmission within 1 week of cataract surgery. Increasing age, medical comorbidity, and inpatient surgery were predictive of readmission. Risk of admission was greater for surgery performed in an office-based setting, but the relatively small number of individuals undergoing surgery in this setting limited the significance of this finding.
- Decision analysis of alternative anesthesia management strategies—This decision analysis indicated that respondents, who were medical experts, had higher preference values for strategies employing retrobulbar or peribulbar block than for strategies employing topical anesthesia. In addition, among strategies employing retrobulbar or peribulbar block, they preferred having an anesthesiologist either present or on call to provide intravenous sedation over having no anesthesiologist present. However, having an anesthesiologist present for every case was associated with increased costs, albeit at increased preference values, relative to simply having an anesthesiologist on call. Additional input from patients regarding their preferences and further clinical research is needed to validate the findings of the decision analysis.
- Analysis of data on patient reports of their cataract surgical experience—Based on 19,250 surgeries from the Study of Medical Testing for Cataract Surgery, this study indicated a high level of satisfaction with anesthesia management regardless of strategy, greater intraoperative pain with topical than with injection anesthesia, and a greater rate of postoperative drowsiness and nausea when intravenous agents were used.
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The published evidence and supplemental analyses indicate that a variety of strategies for anesthesia management of cataract surgery are safe and effective. Our findings do not indicate that a particular strategy is sufficiently superior to others to warrant a change in current practice or a rigid guideline for anesthesia care during cataract surgery.
However, several high priorities for future research were identified:
- First, the methodologic quality of clinical trials in the field should be improved. Specifically, far greater attention should be paid to issues relating to representativeness, description of the intervention, patient comorbidities, length of the surgery, and the standardization of outcomes to allow comparison across studies.
- Second, there is a clear need for information on patient preferences (utilities) for different anesthesia management strategies and outcomes. For example, important tradeoffs are made between the advantages of pain control and depth of sedation on the one hand and the disadvantages of postoperative drowsiness and medication-related complications on the other. Bringing the patient perspective into our understanding of optimal anesthesia management strategies would be very helpful. A better understanding of surgeon preferences for alternative practices would also be important.
- Finally, the cost effectiveness of intravenous sedation and of monitoring by anesthesia personnel should be assessed. Our preliminary decision analysis suggests that the combination of oral sedation with a local block and an anesthesiologist on call may be the most cost-effective approach. However, further research in this area, which would include preference values collected from patients and additional clinical evaluation, is warranted before any final conclusion can be reached.
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Availability of the Full Report
The full evidence report from which this summary was derived was prepared for the Agency for Healthcare Research and Quality by the Johns Hopkins University Evidence-based Practice Center under contract 290-097-0006. Printed copies can be obtained free of charge from the AHRQ Publications Clearinghouse by calling 1-800-358-9295. Requesters should ask for Evidence Report/Technology Assessment Number 16, Anesthesia Management During Cataract Surgery (AHRQ Publication No. 00-E014).
The Evidence Report is also online on the National Library of Medicine Bookshelf.
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AHRQ Publication Number 00-E014
Current as of August 2000