MINI-CAT

Scenario:

A patient is rushed into the emergency room at 4:00 pm c/o dizziness, headache and right sided weakness for 1 hour. Code stroke is activated and the team rushes to call neuro, get a history and all her labs as quickly as possible. The patient states she’s a “hard stick” and after the first failed attempt at obtaining an IV line, they grab the ultrasound to perform an ultrasound-guided peripheral line placement.

The resident has seen the other providers mostly using short-axis technique but asks the attending what he prefers, short-axis or long-axis technique for ultrasound-guided IV placement.

Search Question: Clearly state the question (including outcomes or criteria to be tracked)

Is the short-axis technique associated with greater success than the long-axis technique for ultrasound-guided peripheral IV placement (USGPIV)?

Identify the PICO Elements:

P = patients in the ED/with difficult vascular access 

I = short-axis USGPIV

C = long-axis USGPIV

O = successful USGPIV

PICO search terms:

P	I	C	O
Patients in ED	Short-axis technique	Long-axis technique	Successful ultrasound-guided peripheral IV placement
Emergency department patients	Short-axis USGPIV	Long-axis USGPIV	Effective vascular catheterization
Patients with difficult vascular access	Short-axis ultrasound guided IV placement	Long-axis ultrasound guided IV placement	USGPIV success rate

Search tools and strategy used:

Databases: Science Direct, PubMed, Google Scholar

Terms used: short-axis vs long-axis USGPIV, ultrasound-guided IV placement short- vs long-axis, short-axis or long-axis for ultrasound placed IV 

Articles returned:

• Science Direct: +last 10 years
  • short-axis vs long-axis USGPIV – 3 results
  • ultrasound-guided IV placement short- vs long-axis – 1,405 results
  • short-axis or long-axis for ultrasound placed IV  – 6,830 results
• PubMed: +last 15 tears
  • short-axis vs long-axis USGPIV – 15,597 results
  • ultrasound-guided IV placement short- vs long-axis – 81 results
  • short-axis or long-axis for ultrasound placed IV  – 25,296 results
• Google Scholar: +last 10 years
  • short-axis vs long-axis USGPIV – 32 results
  • ultrasound-guided IV placement short- vs long-axis – 3,840 results
  • effect of tai chi on fall prevention – 14,100 results

How I narrowed down my chosen articles:

I narrowed my choices to a few selected articles based on the type of study done, namely meta-analysis, systematic review and randomized controlled trials to ensure a high level of evidence. I chose articles that directly answered my PICO question, short-axis vs long-axis technique for ultrasound-guided peripheral IV placement.

Chosen articles:

Article 1: Effects of long axis in-plane vs short axis out-of-plane techniques during ultrasound-guided vascular access Yan-Bing Gao, MS a, b, 1, Jun-Hong Yan, MS b, 1, Jian-Min Ma, MS c, 1, Xiao-Na Liu, MD, PhD b, Jing-Yun Dong, MS b, Fang Sun, MS b, Li-Wei Tang, MS b, Jie Li, MD, PhD a,⁎

Link: https://www-sciencedirect-com.york.ezproxy.cuny.edu/science/article/pii/S0735675716000103

Abstract: Background: Currently, whether long-axis in-plane (LA-IP) is superior to short-axis out-of-plane (SA-OOP) dur- ing ultrasound-guided vascular access remains inconclusive. We, therefore, conducted a meta-analysis of ran- domized controlled trials to compare the effects of LA-IP vs SA-OOP techniques in patients undergoing ultrasound-guided vascular access (USGVA). Methods: A computer-based literature search of PubMed, Embase, and the Cochrane Library (up to October 2015) was performed to identify randomized controlled trials that evaluated the effects of LA-IP compared with SA-OOP in patients undergoing USGVA. The primary end point was the first-pass success rate. Secondary end points in- cluded mean time to success, mean attempts to success, and incidence of the complication of hematoma. Weight- ed mean differences (WMDs) and relative risks (RRs) with 95% confidence intervals (CIs) were calculated by random-effects model. Results: Five eligible studies with a total of 470 patients satisfied the inclusion criteria. There was no significant difference for the first-pass success rate (RR, 1.06; 95% CI, 0.91-1.23; P = .44), mean time to success (WMD, 4.78 seconds; 95% CI, −4.43 to 13.99; P = .31), mean attempts to success (WMD, 0.06 times; 95% CI, −0.23 to 0.35; P = .69), and incidence of the complication of hematoma (RR, 2.86; 95% CI, 0.32-25.42; P = .35) between the LA-IP and SA-OOP groups. Conclusions: There is insufficient evidence to definitively choose either LA-IP or SA-OOP in patients undergoing USGVA. Further robustly well-designed trials are warranted to investigate the appropriate technique in patients receiving USGVA.

Type of study: Meta-analysis of randomized controlled trials

Main Points: Searched PubMed, Embase and Cochrane library for randomized controlled studies up to October 2015 comparing the effects of long-axis (in plane) and short-axis (out of plane) techniques in patients who required ultrasound-guided vascular access (USGVA) Primary outcome = first-pass success rate. Secondary outcomes = mean time to success, mean attempts to success and incidence of complication of hematoma.Selection criteria: population – adult or pediatric pt undergoing USGVA, intervention vs control – LA vs SA, outcome measures – both primary and secondary outcomes listed above, study design – only randomized controlled trials. 5 eligible studies were chosen, total of 470 patients. Results showed that there was no significant difference for first-pass success rate between long- and short-axis techniques.Both results for primary outcomes and secondary outcomes did not differ significantly between the two techniques. In terms of safety, both long-axis and short-axis techniques may cause some complications including thrombosis, hematoma, edema, vasospasm and posterior wall damage. Evidence showed that long-axis technique may be better at reducing incidence of hematoma. There is insufficient evidence to claim either technique superior over the other. Further studies are needed to investigate long- vs short-axis for USGPIV/USGVA.

Why I chose it: This article is a high level of evidence, a meta-analysis consisting of only randomized controlled trials. It answers my PICO question directly in comparing long-axis vs short-axis ultrasound-guided peripheral IV placement. It measured multiple outcomes including first-pass success rate, mean time to success, mean attempts to success and incidence of complication of hematoma (and other safety measures).

Article 2: Comparison of short-vs long-axis technique for ultrasound-guided peripheral line placement: a systematic review and meta-analysis Michael Gottlieb 1 , Dallas Holladay 2 , Gary D. Peksa 3

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6067833/

Abstract: Ultrasound-guided peripheral intravenous line (PIV) placement is associated with increased success rates, decreased time to cannulation, and fewer skin punctures than traditional, landmark-based techniques. However, it is unclear which technique is best. This review compares the short-axis (SA) and long-axis (LA) techniques for PIV placement. PubMed, Embase, Scopus, the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, and bibliographies of selected articles were assessed for prospective trials evaluating the first pass success rate of SA vs LA ultrasound-guided PIV placement. Secondary outcomes included time to placement, number of needle passes, and incidence of posterior wall puncture. Data were double extracted into a predefined worksheet and quality was assessed using the Cochrane Risk of Bias tool. Three studies (n = 198) were identified. SA was successful in 125/128 placements (97.7%) and LA technique was successful in 114/128 placements (89.1%). There was an odds ratio of 5.35 (95% CI: 1.46-19.58) in favor of the SA technique. There was no difference in the mean number of needle passes. Time to insertion varied between studies. The existing literature suggests that the SA technique is associated with greater success than the LA technique. Based upon the data, short-axis may be considered as the first approach for ultrasound-guided PIV placement among providers comfortable with both techniques, though further studies are needed.

Type of study: Systemic review and meta-analysis

Main points: PubMed, Embase, Scopus, the Cochrane database of systematic reviews, the Cochrane central register of controller trials and bibliographies were assessed for prospective trials evaluating short-axis vs long-axis ultrasound-guided PIV placement first pass success rate.Primary outcome – first-pass success rate. Secondary outcomes = time to placement, number of needle passes, incidence of posterior wall puncture. A total of 11,094 studies were identified and 3 studies included in the systematic review and meta-analysis. Short-axis was found to be successful in 125/128 PIV placements (97.7%) and long-axis was found to be successful in 114/128 PIV placements (89.1%). No difference was found for mean number of needle passes and time of needle insertion varied from study to study. Based on the literature, short-axis technique was found to have a greater success rate than long-axis technique. Therefore, this technique should be considered as the first approach option for USGPIV for providers who are comfortable with either technique. This study acknowledges that another systematic review and meta-analysis was done comparing short-axis and long-axis for USGPIV in 2016 and found no significant difference between the two but that was done two years prior to this current study, there was limited search criteria and included only one trial which compared the two techniques for PIV placement. This review found two more studies comparing the two which found short-axis to be more successful than long-axis.

Why I chose this article: This article was a systematic review and meta-analysis consisting of randomized controlled trials which yields very high levels of evidence. It consisted of 3 studies directly comparing long-axis vs short-axis techniques. It acknowledged the existence of other studies which did not find any significant difference between the two and stated why this study is more credible than the other one, in favor of short-axis being more successful than long-axis.

Article 3: Comparison between the long-axis/in-plane and short-axis/out-of-plane approaches for ultrasound-guided vascular catheterization: an updated meta-analysis and trial sequential analysis Liu, Chao; Mao, Zhi; Kang, Hongjun; Hu, Xin; Jiang, Shengmao; et al.

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5824754/

Abstract: Background: A long-axis in-plane (LA-IP) approach and a short-axis out-of-plane (SA-OOP) approach are the two main approaches used in ultrasound (US)-guided vascular catheterization. However, the efficacy and safety of these approaches remain controversial. Therefore, we performed this meta-analysis to compare the two techniques in vascular catheterization. Materials and methods: Relevant studies were searched in PubMed, Embase, and the Cochrane Library databases from database inception until August 2017. Randomized controlled trials comparing a long-axis approach with a short-axis approach for US-guided vascular cannulation were selected. The RevMan software was used to analyze the results, and trial sequential analysis (TSA) was further applied to determine whether the currently available evidence was sufficient and conclusive. Results: Eleven studies met the inclusion criteria. Overall, 1,210 patients were included. The total success rate was similar between the SA-OOP and LA-IP approaches for US-guided vascular catheterization (risk ratio [RR], 1.01; 95% CI, 0.99–1.04; P=0.35; I2=48%). In the radial artery (RA; RR, 1.00; 95% CI, 0.96–1.05; P=0.88; I2=49%) and internal jugular vein (IJV; RR, 1.00; 95% CI, 0.98–1.02; P=0.99; I2=0%) subgroups, the total success rate was also similar and was confirmed by the TSA. For populations with subclavian vein (SCV) and axillary vein catheterization, the SA-OOP approach showed a benefit for first-attempt success rate. No significant differences in first-attempt success rate, cannulation times, or complications were found between the two approaches. Conclusion: Despite a similar total success rate between the SA-OOP approach and the LA-IP approach when used for RA and IJV catheterization (as confirmed by TSA), further robust well-designed trials are warranted to evaluate other outcomes. There is insufficient evidence to definitively state that the SA-OOP approach was superior to the LA-IP approach when used for SCV and axillary vein catheterization. High-quality trials are needed to confirm or refute this finding.

Type of study: Meta-analysis

Main points: This meta-analysis compared the two techniques in vascular catheterization and measured both the efficacy and safety.PubMed, Embase and Cochrane library databases were searched until August 2017 of randomized controlled trials. RevMan software was used to analyze the results.348 articles were found relevant but 11 studies met inclusion criteria and 1,210 patients were included. Total success rate between short-axis and long-axis was similar. No significant differences were found in first-attempt success rate, cannulation times and complications. Number of attempts may be reduced when using the short-axis technique vs long-axis technique.Insufficient evidence to confirm that short-axis is superior to long-axis approach when used for venous catheterization and high-quality trials are needed for more evidence. Limitations – due to limited data it is difficult to perform more subgroup or sensitivity analyses. Also, double blinding was not performed due to the features of the trials which could result in performance bias.

Why I chose this article: This article was a meta-analysis of randomized controlled trials, yielding high leveled evidence. It directly studied my PICO question of short-axis vs long-axis for USGPIV. It also studied radial artery and IJV in addition. It was honest about its limitations which it stated clearly at the end.

Article 4: Short- vs long-axis approach to ultrasound-guided peripheral intravenous access: a prospective randomized study Simon A. Mahler MD⁎, Hao Wang MD, PhD, Chadwick Lester RN, Janice Skinner RN, Thomas C. Arnold MD, Steven A. Conrad MD, PhD

Link: https://www.sciencedirect.com/science/article/abs/pii/S0735675710003724

Abstract: Objective: The objective of the study was to determine if the short-axis approach and long-axis approach to ultrasound-guided peripheral intravenous access (USGPIV) differ in success rate, catheter insertion time, and number of needle sticks. Methods: A convenience sample of emergency department patients aged 18 to 65 years with difficult IV access (2 or more failed landmark attempts) was prospectively randomized to short-axis or long-axis USGPIV. Time from skin puncture to catheter insertion (insertion time) and number of needle sticks were recorded. Number of needle sticks and insertion time were compared using Mann-Whitney U tests. Results: Forty subjects were enrolled; 20 were randomized to the short-axis and 20 to the long-axis approach. Success rate was 95% (19/20; 95% confidence interval, 85%-100%) in the short-axis group compared with 85% (17/20; 95% confidence interval, 69%-100%) in the long-axis group. All 3 subjects with failed IV placement in the long-axis group had successful rescue USGPIV placement in short axis. Median insertion time was 34 seconds (interquartile range, 35 seconds) for the short-axis group compared with 91 seconds (interquartile range, 59 seconds) for the long-axis group (P = .02). Mean number of needle sticks was 1.5 (±SD 0.7) in the short-axis group compared with 1.4 (±SD 0.7) in the long-axis group (P = .82). Conclusions: Short-axis USGPIV technique required less insertion time than the long-axis technique. Success rate was higher in the short-axis group, but this difference was not statistically significant. However, all of the failed IVs in the long axis were rescued successfully in short axis.

Type of study: Prospective randomized study

Main points: Studied if short-axis vs long-axis approach to USGPIV differ in success rate, catheter insertion time (defined as time from skin puncture to catheter insertion) and number of needle sticks. Sample of emergency department patients ages 18-65 years old with difficult IV access defined by 2 or more failed landmark attempts. Sample was prospectively randomized to short-axis or long-axis technique for USGPIV.  40 subjects were included in the trial, half to short-axis and half to long-axis. Patients were excluded if they were younger than 18 or older than 65, were pregnant or had unstable trauma. Other patients were excluded if they required a central line rather than a peripheral IV line bc of hemodynamic instability, need for multiple IV drips or anticipated ICU admission. Short-axis group = 95% success rate, long-axis group = 85% success rate Short-axis group median insertion time = 34 seconds, long-axis group median insertion time = 91 seconds. Short-axis mean number of needle sticks = 1.5, long-axis mean number of needle sticks = 1.4Results showed that short-axis USGPIV technique required less time for insertion than long-axis technique. Although not statistically significant, success rate was higher than short-axis group. All failed IVs in the long-axis group were re-done with short-axis technique and was successful.

Why I chose this article: This article is a randomized controlled trial which yields a high level of evidence and was different than my other articles, all systematic reviews and meta analyses. The trial conducted a study on my exact PICO question.

Article 5: Needle tip visualization during ultrasound-guided vascular access: short-axis vs long-axis Michael B. Stone MDa,⁎, Cynthia Moon MDa, Darrell Sutijono MDa, Michael Blaivas MDb

Link: https://www.sciencedirect.com/science/article/abs/pii/S0735675708008164

Abstract: Objectives: Ultrasound guidance for central venous catheterization improves success rates and decreases complications when compared to the landmark technique. Prior research has demonstrated that arterial and/or posterior vein wall puncture still occurs despite real-time ultrasound guidance. The inability to maintain visualization of the needle tip may contribute to these complications. This study aims to identify whether long-axis or short-axis approaches to ultrasound-guided vascular access afford improved visibility of the needle tip. Methods: A prospective trial was conducted at a level I trauma center with an emergency medicine residency. Medical students and residents placed needles into vascular access tissue phantoms using long-axis and short-axis approaches. Ultrasound images obtained at the time of vessel puncture were then reviewed. Primary outcome measures were visibility of the needle tip at the time of puncture and total time to successful puncture of the vessel. Results: All subjects were able to successfully obtain simulated blood from the tissue phantom. Mean time to puncture was 14.8 seconds in the long-axis group and 12.4 seconds in the short-axis group (P = .48). Needle tip visibility at the time of vessel puncture was higher in the long-axis group (24/39, 62%) as opposed to the short-axis group (9/39, 23%) (P = .01). Conclusions: In a simulated vascular access model, the long-axis approach to ultrasound-guided vascular access was associated with improved visibility of the needle tip during vessel puncture. This approach may help decrease complications associated with ultrasound-guided central venous catheterization and should be prospectively evaluated in future studies.

Type of study: Prospective randomized study

Main points: Prospective randomized study of novice operators using both short- and long-axis techniques for ultrasound-guided peripheral IV placement on a tissue phantom. Study conducted at a level 1 trauma center with emergency room residency. Study population consisted of experienced senior medical students and first year residents with almost no experience with USGPIVParticipants received teaching and education regarding USGPIV and both techniques but no hands on practice before participating in the study. Primary outcome measure was time from first tissue puncture to first successful vessel puncture was measured. Successful puncture was judged by a “flash” of simulated blood in the syringe. Other measures included year of training, number of previously done USGPIV procedures and overall preference of short or long axis technique. 39 subjects participated = 22 third- and fourth-year medical students and 17 EM interns. Needle tip visibility at the time of vessel puncture was higher in the long axis group – 62% of long-axis attempts and 23% of short-axis attempts. There was no significant difference in time to vessel puncture between the two groups and no differences in any other measures. Other studies have found that novice sonologists successfully placed peripheral IV with ultrasound in less time when using short-axis but this study found no significant time difference between the two. Their results show that long-axis approach affords improved visualization of the tip of the needle at the time of puncture.

Why I chose this article: This article is a randomized prospective study which is highly credible. I liked that this article focused mostly on needle tip visualization and found that the long-axis may be better and easier for visualizing the needle tip at the (real) time of the puncture.

Summary of the Evidence:

Author (Date)	Level of Evidence	Sample/Setting (# of subjects/ studies, cohort definition etc. )	Outcome(s) studied	Key Findings	Limitations and Biases
Yan-Bing Gao, MS a, b, 1, Jun-Hong Yan, MS b, 1, Jian-Min Ma, MS c, 1, Xiao-Na Liu, MD, PhD b, Jing-Yun Dong, MS b, Fang Sun, MS b, Li-Wei Tang, MS b, Jie Li, MD, PhD a,⁎    2016	Meta-analysis of randomized controlled trials	Systematic search of PubMed, Embase and the Cochrane library to identify randomized controlled trials. 5 eligible studies included with a total of 470 patients.	Comparison of effects of long-axis / in-plane vs short-axis / out-of-plane techniques in patients undergoing ultrasound-guided vascular access (USGVA)	Findings were insufficient to definitively conclude that long-axis or short-axis is more superior. More well-designed and credible trials are required to investigate and determine the more successful technique for USGVA.	Present study is based on only 5 RCTs with varying factors and variables. Almost all trials were not blinded which could lead to bias. Other aspects such as clinical outcomes were unable to be measured including patient pain and satisfaction scores.
Michael Gottlieb  , Dallas Holladay  , Gary D. Peksa   2018	Systematic review and meta-analysis	Systematic search of PubMed, Embase, Scopus and the Cochrane database of systematic reviews, the Cochrane central register of controlled trials and bibliographies of selected articles. 3 studies included comprising 198 total assessments.	Compares the short-axis and long-axis techniques for PIV placement.	Short-axis technique is associated with greater success than long-axis technique and should be considered as the first approach for ultrasound-guided PIV placement among providers who are comfortable with both techniques.	Limited number of studies consisting of only 198 assessments. Two of those studies were performed on phantom tissue and not live tissue.
Liu, Chao; Mao, Zhi; Kang, Hongjun; Hu, Xin; Jiang, Shengmao; et al.   2018	Meta-analysis and trial sequential analysis	Systematic search of PubMed, Embase and Cochrane library databases including randomized controlled trials. 11 studies included, total of 1,210 patients.	Comparison of short-axis vs long-axis techniques for vascular catheterization.	Similar total success rate was found between short-axis and long-axis approach for IJV catheterization however there is insufficient evidence to definitively state that short-axis is superior for other venous access.	Heterogeneity observed between studies in regards to blood vessel type, operator experience, ultrasound equipment and outcome definition. Double blinding was not performed.
Simon A. Mahler MD⁎, Hao Wang MD, PhD, Chadwick Lester RN, Janice Skinner RN, Thomas C. Arnold MD, Steven A. Conrad MD, PhD     2010	Prospective randomized study	Convenience sample of ED patients aged 18-65 years old with difficult IV access prospectively randomized to short-axis or long-axis USGPIV. 40 subjects enrolled, 20 randomized to short-axis and 20 to long-axis.	Determine if short-axis approach and long-axis approach to USGPIV differ in variables including success rate, number of needle sticks and catheter insertion time.	Short-axis technique had a higher success rate for USGPIV (not very statistically significant) and required less insertion time than the long-axis technique. All the failed IVs using long-axis were rescued using the short-axis technique.	Potential for selection bias as it was a convenience sample. Times in the study were self-reported which can also lead to biases. Another bias was small number of sonographers included.
Michael B. Stone MDa,⁎, Cynthia Moon MDa, Darrell Sutijono MDa, Michael Blaivas MDb   2008	Prospective randomized study	39 participating subjects;  22 were third- and fourth-year medical students, 17 were emergency medicine interns at a level 1 trauma center.	Identify which ultrasound-guided vascular access technique, long-axis or short-axis, affords better visualization of the needle tip during procedure time.	Long-axis technique was found to have improved visibility of the needle tip at the time of vessel puncture compared to short-axis, which may decrease complications associated with USGVA.	Tissue phantom was used as opposed to live tissue. Results were obtained during a single session and so results are not based on continued practice, which may change them.

Conclusions:

1. Findings were insufficient to definitively conclude that long-axis or short-axis is more superior. More well-designed and credible trials are required to investigate and determine the more successful technique for USGVA.
2. Short-axis technique is associated with greater success than long-axis technique and should be considered as the first approach for ultrasound-guided PIV placement among providers who are comfortable with both techniques.
3. Similar total success rate was found between short-axis and long-axis approach for IJV catheterization however there is insufficient evidence to definitively state that short-axis is superior for other venous access.
4. Short-axis technique had a higher success rate for USGPIV (not very statistically significant) and required less insertion time than the long-axis technique. All the failed IVs using long-axis were rescued using the short-axis technique.
5. Long-axis technique was found to have improved visibility of the needle tip at the time of vessel puncture compared to short-axis, which may decrease complications associated with USGVA.

Overall Conclusion:

Although inconclusive due to limited research, it seems that short-axis technique proves to be more effective at successful ultrasound-guided peripheral IV placement in patients with difficult IV access and should therefore be the initial choice of technique. Further research needs to be done with greater sample sizes to definitively conclude that short-axis has a greater success rate at vascular catheterization compared to long-axis.

Weight of Evidence:

1. Article #2 is a systematic review and meta-analysis published in the last 4 years and searched articles with high levels of evidence including PubMed, Embase, Scopus, the Cochrane Database of Systematic Reviews, the Cochrane Central Register of controlled trials and bibliographies of selected articles and so I weigh this article the highest. This is also the first systematic review and meta-analysis comparing short-axis with long-axis technique specifically for peripheral IV line placement. A total of 11,904 studies were identified but only 3 were included comprising of 198 total assessments. These chosen studies were prospective, observational and randomized, controlled trials measuring both primary and secondary outcomes. Topic experts were consulted with to help identify any further relevant studies.
2. Article #3 is a meta-analysis and trial sequential analysis also published in the last 4 years and searched articles with high levels of evidence including PubMed, Embase and Cochrane library databases consisting of all randomized controlled trials and so I weigh this article the 2^nd highest. A total of 348 studies were collected with only 11 included in the study including 1,210 patients. Sample size of the studies ranged from 40-190 subjects. The internal validity of the study was assessed using the Cochrane Collaboration Risk of Bias tool. Statistical analysis was performed using the RevMan software for outcome measurements. 
3. Article #1 is meta-analysis of randomized controlled trials done in the past 10 years and searched articles with high levels of evidence including PubMed, Embase and the Cochrane library to identify randomized controlled trials only and so I weigh this article the 3^rd highest. All data was extracted using 2 independent investigators, YBG and JHY. The quality of the RCTs were evaluated by the Jadad scale. The study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. A total of 235 articles were identified and 5 were included in the study consisting of 470 total patients. All operations were performed by experienced providers including physicians, nephrologists, anesthetists and intensivists.
4. Article #4 is a prospective randomized study done in the past 11 years and is weighed fourth. This trial consisted of a convenience sample of ED patients aged 18-65 years, which is a broad range of ages, minimizing results affected by specific ages. Patients were excluded from the study if they were younger than 18, older than 65, pregnant or experienced an unstable trauma. Randomization at a 1:1 ratio was achieved using a computer-generator random number sequence for the subjects. Intention-to-treat analysis was performed and scores were compared using the Mann-whitney U tests.
5. Article #5 is a prospective randomized study done in the past 13 years and is weighed fifth, Study consists of 39 subjects, 22 of them third- and fourth-year medical students and 17 of them emergency medicine interns at a level 1 trauma center. A two-tailed Fisher exact test as used to analyze the primary outcome, needle tip visibility. A paired student t test was used to analyze the time to puncture of the vein. Due to the phantom tissue used and the study measuring performance on one occasion with no room for a practice curve, this article is ranked last.

Magnitude of Effects:

1. Article #1 – “The pooled results indicated that there was no significant difference for the first-pass success rate (5 RCTs [9–13]; RR, 1.06; 95% CI, 0.91-1.23; P = .44; P = .0006 for heterogeneity; I2 = 80%; Fig. 3A), mean time to success (4 RCTs [9,10,12,13]; WMD, 4.78 seconds; 95% CI, −4.43 to 13.99; P = .31; P = .0003 for heterogeneity; I2 = 84%; Fig. 3B), mean at- tempts to success (4 RCTs [9–11,13]; WMD, 0.06 times; 95% CI, − 0.23 to 0.35; P = .69; P = .0007 for heterogeneity; I2 = 82%; Fig. 3C), and inci- dence of the complication of hematoma (3 RCTs [9,12,13]; RR, 2.86; 95% CI, 0.32-25.42; P = .35; P = .002 for heterogeneity; I2 = 85%; Fig. 3D) between the LA-IP and SA-OOP groups. Here, heterogeneity was signif- icant for the first-pass success rate. Further exclusion of any single study did not resolve the heterogeneity and did not change the pooled results. Subsequently, we performed subgroup analyses for the first-pass suc- cess rate to determine the effect of various exclusion criteria according to ultrasound type, vessel type, and sample size (Table 2). These exclu- sion criteria did not obviously alter the overall combined RR of the first- pass success rate, which ranged from 0.92 (95% CI, 0.51-1.67; P = .79) to 1.73 (95% CI, 0.78-1.59; P = .54).” (Yan-Bing Gao et al., 2016)
2. Article #2 – “Overall, the short-axis technique was successful in 125 of 128 total placements (97.7%). The long-axis technique was successful in 114 of 128 total placements (89.1%). There was an OR of 5.35 (95% CI: 1.46 to 19.58) in favor of the short-axis technique (Figure 2). There was no evidence of statistical heterogeneity with an I2 of 0%. Funnel plot analysis demonstrated no evidence of publication bias, though assessment was limited by the number of studies. The mean number of needle passes was not significantly different between the short- and long-axis techniques with a mean difference of 0.10 needle passes (95% CI: -0.33 to 0.53). The insertion time could not be quantitatively combined due to differences in reporting strategy. Mahler et al. identified a statistically significant reduction in time for the short-axis technique [13], while Clemmesen et al. identified a statistically significant reduction in time for the long-axis technique (Table 2) [14]. Erickson et al. did not identify a significant difference between either technique [12]. No studies assessed rates of posterior wall puncture for PIV placement.” (Michael Gottleib et al, 2018)
3. Article #3 – “Nine studies17,19,21–27 reported the first-attempt success rate. There was no significant difference between the LA-IP approach group and the SA-OOP approach group (RR, 1.14; 95% CI, 0.96–1.35, P=0.14, I2=80%; Figure 5). Due to remarkable heterogeneity, preset subgroup analyses were performed for the populations with RA catheterization (RR, 1.03; 95% CI, 0.77– 1.38; P=0.85, I2=84%; Figure 5) and IJV catheterization (RR, 1.12; 95% CI, 0.84–1.49; P=0.33; I2=74%; Figure 5). No significant differences were observed. For populations with SCV catheterization25 and axillary vein catheterization,24 the SA-OOP approach showed a benefit.” (Chao Liu et al., 2018)
4. Article #4 – “Over the 22-month study period during April 2008 to February 2010, 40 patients were enrolled. A total of 20 subjects were randomized to the short-axis group and 20 to the long-axis group. Demographic characteristics of subjects are summarized in Table 1. Success rate was 95% (19/20; 95% confidence interval, 85%-100%) in the short-axis group compared with 85% (17/20; 95% confidence interval, 69%- 100%) in the long-axis group. All 3 subjects with failed IV placement in the long-axis group had successful rescue USGPIV in short axis. One of the 3 subjects with a failed procedure in long axis was switched to short axis on the basis of poor vein visualization without a needle stick in long axis. One patient randomized to short axis was unsuccessful in both techniques. Median insertion time was 34 seconds (interquartile range [IQR], 35 seconds) for the short-axis group compared with 96 seconds (IQR, 59 seconds) for the long-axis group (P = .0.02). In the short-axis group, the median total procedure time was 201 seconds (IQR, 331 seconds) compared with 236 (IQR, 378 seconds) seconds in the long-axis group (P = .0.68). Mean number of needle sticks was 1.5 (±SD 0.7) in the short-axis group compared with 1.4 (±SD 0.7) in the long-axis group (P = .82). Patient satisfaction scores and complication rates did not significantly differ between groups. Results are summarized in Table 2.” (Simon A. Mahler et al., 2010)
5. Article #5 – “Thirty-nine subjects participated in the study; 22 were third- and fourth-year medical students and 17 were emergency medicine interns. All subjects were able to successfully obtain simulated blood from the tissue phantom. Needle tip visibility at the time of vessel puncture was higher in the long-axis group: the needle tip was visible at the time of puncture in 24 (62%) of 39 long-axis attempts and in 9 (23%) of 39 short-axis attempts (P = .01). There was no significant difference in time to vessel puncture in the long- axis and short-axis groups: mean time to puncture was 14.8 seconds in the long-axis group and 12.4 seconds in the short- axis group (P = .48). There were no significant differences in performance among students and interns. Procedure order had no effect on needle tip visibility or time to puncture, and there was no difference in performance between participants who were assigned to short-axis vs long-axis for their initial attempts. Of 39 participants, 27 (69%) preferred the long- axis approach.

Two of the investigators (MS and MB) independently reviewed 34 still images obtained from attempts in both the short and long axes. Interobserver agreement was very good: κ = 0.881 (95% confidence interval, 0.72-1.04).” (Michael B. Stone et al., 2008)

Clinical Bottom Line and significance:

Ultrasound-guided peripheral IV placement is one of the most common procedures performed in the emergency department, typically used when a patient has difficult venous access. To  note, there are certain comorbidities including diabetes, sickle cell disease and IV drug use which is associated with difficult IV placement and would commonly require an ultrasound to acquire successful vascular catheterization.

Limited yet credible research has been done on whether short-axis or long-axis technique for ultrasound-guided peripheral IV placement (USGPIV) is more successful. The primary outcome studied in all of my chosen articles was first-pass success rate. A few of my articles came to the conclusion that short-axis technique was superior to long-axis in first-pass success rate and more effective at achieving successful USGPIV. Despite some articles concluding that their results may not be statistically significant, short-axis overall seems to be the technique of choice in providers who are comfortable with both techniques. Other factors were studied such as complications including hematoma formation and needle tip visibility at time of procedure. Short-axis was found to result in less complications and to rescue failed PIV placements which were placed long-axis initially.

It seems that short-axis is more effective at USGPIV in patients with difficult IV access and should be used by providers as the initial choice of technique. Overall, more research needs to be done with greater sample sizes to conclude that short-axis has a greater success rate than long-axis in USGPIV.

Other Considerations:

Further studies need to be conducted with greater sample sizes in order to come to a a definitive conclusion. A few articles conducted studies using phantom tissue and so ideally more studies should be done on live tissue. 

**PICO RT 6 WK 1