Meta Analysis Ultrasonic locating devices for central venous cannulation: meta-analysis.
This review may be edited
Summary
Posted By:	Dr. N. Ramakrishnan
E-Mail:	naresh@med.usyd.edu.au
Posted Date:	23/09/2003
Title:	Ultrasonic locating devices for central venous cannulation: meta-analysis.
Authors:	Hind D, Calvert N, McWilliams R, Davidson A, Paisley S, Beverley C, Thomas S.
Reference:	BMJ. 2003 Aug 16;327(7411):361
Link:	Click here for a direct link to the paper. A password may be required for access to fulltext.
Abstract:	OBJECTIVES: To assess the evidence for the clinical effectiveness of ultrasound guided central venous cannulation. DATA SOURCES: 15 electronic bibliographic databases, covering biomedical, science, social science, health economics, and grey literature. DESIGN: Systematic review and meta-analysis of randomised controlled trials. Populations Patients scheduled for central venous access. INTERVENTION REVIEWED: Guidance using real time two dimensional ultrasonography or Doppler needles and probes compared with the anatomical landmark method of cannulation. DATA EXTRACTION: Risk of failed catheter placement (primary outcome), risk of complications from placement, risk of failure on first attempt at placement, number of attempts to successful catheterisation, and time (seconds) to successful catheterisation. DATA SYNTHESIS: 18 trials (1646 participants) were identified. Compared with the landmark method, real time two dimensional ultrasound guidance for cannulating the internal jugular vein in adults was associated with a significantly lower failure rate both overall (relative risk 0.14, 95% confidence interval 0.06 to 0.33) and on the first attempt (0.59, 0.39 to 0.88). Limited evidence favoured two dimensional ultrasound guidance for subclavian vein and femoral vein procedures in adults (0.14, 0.04 to 0.57 and 0.29, 0.07 to 1.21, respectively). Three studies in infants confirmed a higher success rate with two dimensional ultrasonography for internal jugular procedures (0.15, 0.03 to 0.64). Doppler guided cannulation of the internal jugular vein in adults was more successful than the landmark method (0.39, 0.17 to 0.92), but the landmark method was more successful for subclavian vein procedures (1.48, 1.03 to 2.14). No significant difference was found between these techniques for cannulation of the internal jugular vein in infants. An indirect comparison of relative risks suggested that two dimensional ultrasonography would be more successful than Doppler guidance for subclavian vein procedures in adults (0.09, 0.02 to 0.38). CONCLUSIONS: Evidence supports the use of two dimensional ultrasonography for central venous cannulation.
Are the Results Valid?
1. Did the overview address a focused clinical question?
	Yes, the authors state the objective of their study was to assess the evidence for the clinical effectiveness of ultrasound guided central venous cannulation.
2. Were the criteria used to select articles for inclusion appropriate?
	Yes, The authors explicitly state their criteria for article selection: clinical effectiveness of two dimensional ultrasound guidance or Doppler ultrasound guidance for the placement of central venous lines; comparison of ultrasonography with the landmark method or the surgical cut-down procedure; inclusion of one or more of several outcomes—number of failed catheter placements, number of complications from catheter placement, risk of failure at first attempt, number of attempts to successful catheterization, and time (seconds) to successful catheterization. The authors also state that they only considered randomized control trials.
3. Is it unlikely that important, relevant studies were missed?
	Yes, they searched 15 electronic bibliographic databases from inception to October 2001. This was combined with a review of bibliographies retrieved. Due to the nature of the content, it is unlikely that important trials were missed however they could have avoided a possible publication bias by including all articles & by not restricting their review to English language citations only.
4. Was the validity of the included studies appraised?
	Yes, validity was appraised. It is interesting to note that none of the studies reported allocation concealment.
5. Were assessments of studies reproducible?
	No, the authors do not provide a measure of agreement between two independent reviewers with regards to study validity.
6. Were the results similar from study to study?
	Yes, there was no significant statistical heterogeneity when looking at failure of catheter placement, but the analysis for complications is not revealed in the paper.
What are the Results?
1. What are the overall results of the overview?
	Two dimensional ultrasound guidance (2D USG) compared to landmark method Failed catheter placement •2D ultrasound guidance in internal jugular veins (IJV) in adults decreased failure rates RRR 0.86 (95%CI 0.67 to 0.94, p <0.001), in subclavian vein (SCV) RRR: 0.86 (95% CI 0.43 to 0.96, p = 0.006) & in the femoral vein RRR:0.71 (95% CI -0.21 to 0.93, p = 0.09) Complications with catheter placement •Lower complications using 2D USG in IJV in adults, RRR 0.57 (95% CI 0.013 to 0.78 p = 0.002) in SCV RRR 0.9 (95% CI 0.29 to 0.99, p = 0.02). Doppler ultrasound guidance (DUG) with the landmark method. Failed catheter placement •DUG in IJV in adults decreased failure rates RRR 0.61 (95%CI 0.08 to 0.83, p = 0.03), but in SCV increased the failure rate RRR: -0.48 (95% CI -1.14 to -0.03, p = 0.03
2. How precise were the results?
	See above for pooled estimates, 95% CI & p values
Will the Results Help Me In Caring For My Patients?
1. Can the results be applied to my patient care
	Yes, the trials included in this review are fairly representative of the critically ill patient who requires central venous access. (note however that it clubbed together studies of varying operator experience and time criticalness)
2. Were all clinically important outcomes considered?
	No, The studies also only reported on surrogate outcomes. Also all complications were lumped together for analysis.
3. Are the benefits worth the harms and costs?
	Not sure, It appears that using 2D ultrasound guidance improves the success of cannulating the adult internal jugular vein on first attempt, and there are fewer complications associated with this. It is not clear whether this does indeed translate to better patient outcomes as the studies do not address that. Cost analysis was not a part of this study but the authors have reported this elsewhere
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