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From the Departments of *Anesthesiology and
Community and Preventive Medicine, University of Rochester, Rochester, New York.
Address correspondence to Peter L. Bailey, MD, Department of Anesthesiology, Box 604, 601 Elmwood Ave., Rochester, NY 14642. Address e-mail to peter_bailey{at}urmc.rochester.edu.
| Abstract |
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METHODS: We conducted an electronic survey of all members of the Society of Cardiovascular Anesthesiologists. Univariate and multivariate logistic regressions were used to assess the association between the frequency of US use and hospital and physician factors. All tests were two-sided, and a P value <0.05 was considered statistically significant.
RESULTS: Of the 4235 members, 1494 responded (response rate = 35.3%). Two-thirds of the respondents never, or almost never, use US, whereas only 15% always, or almost always, use US. Thirty-three percent of the respondents never, or almost never, have US available, whereas 41% stated that US is always, or almost always, available. Availability of US equipment was strongly associated with US use for CVC (adj OR = 18.9; P value <0.001). The most common reason cited for not using US was "no apparent need for the use of US" (46%). When US was used, rescue or screening approaches were more common (72%) than real-time use (26%).
CONCLUSIONS: The use of US during CVC remains limited and is most strongly associated with the availability of equipment. Screening and rescue use of US are more common than real-time guidance. Our survey suggests that current use of US during CVC differs from existing evidence-based recommendations.
| Introduction |
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| METHODS |
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Before sending an email to all members of the SCA, approval was obtained from the University of Rochester Information Technology Department to assure them that the mass emailing was not "spam." All members of the Society of Cardiovascular Anesthesiologists were emailed a brief explanation of the survey and requested to use a provided link to bring them to the survey instrument which was housed on a web site located on the University of Rochester Department of Anesthesiology server. Survey responses were stored in a Microsoft SQL database (Microsoft Corporation (2006); Microsoft Windows Server System: Microsoft Sequel Server. Web link: http://www.microsoft.com/sql/default.mspx; accessed March 29, 2006) and were then exported to a Microsoft Excel spreadsheet. A reminder email was sent to non-responders wk after initial survey distribution. Non-responders were identified by cross-checking the email address of responders against the global email list of members of the SCA.
Univariate and multivariate logistic regression were used to assess the association between the frequency of US use and hospital or physician factors, such as practice setting and type. The frequency of US use, measured on a Likert scale, was transformed to a binary variable: frequent use (scores of 4 or 5) or infrequent use (scores of 0 and 1). Intermediate scores (2 and 3) were not included in the univariate and multivariate analyses because they were too close to each other to assign to either a "frequent use of US" versus an "infrequent use of US" category. Hospital and physician factors with P values <0.25 in the univariate analyses were included in the final multivariate logistic regression model. All statistical analyses were performed in STATA version 8.2 (College Station, TX). The analyses did not control for clustering of physicians within hospitals due to the absence of physician and hospital identifiers. All tests were two-sided and a P value <0.05 was considered statistically significant.
We were unable to analyze non-responder bias because we did not have access to demographic information for non-responders because of confidentiality concerns.
| RESULTS |
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Physician preferences with respect to the use of US are shown in Table 2. Sixty-seven percent of the respondents never, or almost never, used US to perform CVC. Only 15% of respondents always, or almost always, use US for CVC. The most common reasons for not using US were the perception that it was unnecessary (46%) and lack of availability of US equipment (18%). When US was used for CVC, it was most commonly used either as a rescue technique after first attempting CVC without the use of US (40%) or as a means of screening patients before performing CVC (31%). Of the respondents who reported using US, only 26% used it in real-time to guide CVC.
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The most commonly reported complication of CVC was carotid puncture (75%) followed by pneumothorax (17%; Table 3). Additionally, 3.2% of the respondents reported having observed carotid injury, 1.1% reported strokes, and 1% reported foreign body embolism in any of their patients.
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The results of the analysis of the association between the frequency of US use and hospital or physician factors are displayed in Figures 1 and 2, and in Table 4. In the multivariate analysis, the availability of US equipment was strongly associated with US use for performance of CVC. In hospitals where US equipment was always available, respondents were much more likely to use US than in hospitals where such equipment was almost never available (adj OR = 18.9; P value <0.001). Physicians in academic practice (adj OR = 2.07; P value <0.001) and physicians practicing in Veterans Administration hospitals (adj OR = 3.42; P value <0.005) were more likely to use US than physicians in private practice. Physicians who had completed training between 1990 and 1999 (adj OR = 1.83; P value = 0.021) were more likely to use US than recent graduates (2000 and after). Critical care practitioners used US more frequently than cardiac anesthesiologists (adj OR = 3.30; P value = 0.046). High volume practitioners (>100 central lines/year) tended to be less likely (adj OR = 0.36; P value = 0.062) to use US than low volume practitioners (120 central lines/year).
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| DISCUSSION |
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In our multivariate analysis, availability of equipment was most strongly associated with US use during CVC. Availability may be a resource issue; the cost of US equipment designed for use during CVC ranges from $12,000 to $30,000. However, US devices can serve multiple purposes (e.g., identification of saphenous veins suitable for harvesting, regional anesthesia) and costs can be shared. Routine US guidance during CVC has been estimated to be cost-effective (6). Availability may be a logistical issue and delays in obtaining equipment were also cited as a barrier to US use. Of note, even though 40.9% of respondents reported US to always or almost always be available, only 15% of respondents use US always or almost always. Thus availability does not fully explain the lack of US use. Nearly 10% of respondents believed the use of US prolonged the time required for CVC, despite evidence that US shortens procedure time and increases success rate (2,3,9,15).
Physicians in academic or Veterans Administration hospital settings were significantly more likely to use US, as were critical care physicians. We did not explore what factors in these settings might explain these different practices. Certain settings may have a greater availability of resources. It is plausible that teaching hospitals are more likely to use US for trainee instruction and patient care. On the other hand, we did not find that more recently trained anesthesiologists used US more frequently, nor did we observe an effect of fellowship training on the use of US. In addition, the existence of a practice protocol concerning CVC did not influence the use of US.
Nearly half (45.7%) of our respondents reported "no apparent need for the use of US during CVC" as the most common explanation for not using US. This perception existed even though recognized problems were reported to have been observed. For example, 75% of our respondents reported to have witnessed carotid artery puncture. Significant complications were also reported to have been observed including carotid artery injury (3.2%), pneumothorax (17%), and hemothorax (4%). These and other problems are well established to occur between 2% and 15% of the time when US is not used for CVC (2,3,1619). Interestingly, Domino et al. (1) suggested that of the 110 patients included in a closed claims analysis related to central venous access, 48 had injuries that were deemed avoidable and that US might have helped prevent injury in 28. This would equate to a 25% reduction in injuries. Domino et al. highlighted the limitations of closed claims studies, and they noted that the influence of new technology such as US on liability issues could not be fully evaluated. They also found that the proportion of claims related to central venous access problems were increasing over time, whereas problems arising from use and maintenance of central lines were decreasing.
The individual perception that US is not needed during CVC may be at odds with the aim of improving patient safety. The incidence of significant complications associated with CVC in contemporary practice is unknown. It is possible that the most common complication, the problem of needle puncture of the carotid artery, is of infrequent consequence to patients and/or not of substantial concern in and of itself to most clinicians. However, because approximately 5 million CVCs are performed every year (10) in the United States, even a low incidence (e.g., 0.5%) of significant complications would result in a concerning absolute number (e.g., 25,000) of such problems.
Of the minority of respondents who reported using US, only 26% of them use it in real-time, as is most widely studied and recommended. More commonly, US was used either as a rescue or as a screening tool. The use of US as a rescue tool, while potentially beneficial, has not been well studied. Rescue approaches, typically performed after initial methods have failed and possibly resulted in complications, may not be as likely to produce the same level of benefit as approaches that incorporate US from the beginning. However, some reports have demonstrated that the use of rescue US can facilitate CVC in patients with known difficult central venous access (20).
The usefulness of US as a screening tool also has not been extensively studied. Screening may be preferred by clinicians because it allows an assessment of vascular anatomy and the accuracy of landmarks and it is simpler to perform than real-time approaches. Prepuncture US screening has been reported to be superior to the landmark method (21). Hayashi and Amano (22) also reported that screening improved the jugular vein access rate when compared withthe landmark method, but that the overall success rate was only improved in a subset of patients (22%) in whom respiratory variations in the internal jugular vein could not be identified with the naked eye (22). It is intuitive that screening with US would be helpful given the known variability in the anatomy of the right internal jugular vein and carotid artery (2325) and inaccuracy of surface landmarks (26). Current recommendations do not include screening approaches to CVC (8), and additional study is required to determine their utility. Of note, Current Procedural Terminology (CPT®) includes coding allowing reimbursement only for direct US guidance during CVC (27).
To avoid carotid artery injury, clinicians use various means (Table 2) to verify that they have accessed a vein and not an artery (28). We found that 46% of responding practitioners rely on the color or pulsatility of blood to confirm venous versus arterial access. Although some authors report that the color of the blood obtained from an accessed vessel may be accurate under many conditions (29), others have not found relying on color and/or pulsatility to be reliable (30,31). It is commonly recommended that the intravascular pressure of the vessel accessed be measured either semiquantitatively, via physical manometry with a sterile IV tubing, or with a transducer (to include assessment of associated pressure waveform), before inserting a large-bore introducer. Visualization of the guidewire inserted through the access needle in the superior vena cava and/or right atrium in settings where transesophageal echocardiography is used is another objective verification method. Domino et al. (1) suggested that, similar to what was found with US, pressure waveform monitoring could have helped prevent complications in 25 of the 48 patients in a closed claims analysis whose injuries during central venous access were deemed avoidable. Our finding that nearly half of the respondents still use color or pulsatility of blood to confirm central venous access suggests another area for possible safety improvement.
Our study has several methodological limitations. First, our response rate was only 35%. However, this response rate is typical, and within the range of response rates (26%47%) found in published electronic surveys (3239). Despite lower response rates, Braithwaite et al. (39) in a systematic review, and others (36), recognize that Internet-based surveys have advantages over postal and telephone surveys of health professionals; these include lower cost, quicker responses, and facilitated data gathering and analysis. Second, we could not eliminate the possibility of nonresponder bias. Confidentiality issues prevented us from assessing demographic information for the nonresponders. Braithwaite et al. (39) note the methodological limitations mentioned above are particularly problematic with electronic surveys. Indeed, recently published electronic survey reports in the anesthesia literature have similar response rates and limited ability to address nonresponder bias (40). The distribution of the age of our responders (based on the year training was completed) and practice type mitigates against the strong likelihood of significant responder bias related to these factors at least. In addition, our results do highlight current practices among the substantial number of responders (1494) who did reply to our survey. Nevertheless, our response rate and the possibility of nonresponder bias limit the generalizability of our findings. Finally, our findings are based on a survey of a specific population of practitioners and may not be generalizable to other groups of anesthesiologists or clinicians.
In summary, we found that the use of US during CVC of the right internal jugular vein remains limited. Availability of equipment and practitioners perceptions of the utility of US contribute to this. In general, our findings are consistent with reports that recommendations intended to improve patient safety are having limited success in being disseminated in clinical practice (12). Greater resource allocation, efforts directed toward increasing the use of US during training, and attention to other means of reducing complications related to CVC (e.g., verification of venous and not arterial access, specific care protocols) may play a role in systematically improving patient safety during CVC.
| ACKNOWLEDGMENTS |
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| Footnotes |
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Supported by the Department of Anesthesiology of the University of Rochester.
This article has supplementary material on the Web site: www.anesthesia-analgesia.org.
| REFERENCES |
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