Agitated Saline Bubble−Enhanced Ultrasound for Assessing Appropriate Position of Hemodialysis Central Venous Catheter in Critically Ill Patients (2017)

Renal replacement therapy is recommended to be initiated immediately in patients with life-threatening acute kidney injury (AKI)−related symptoms. Ultrasound-guided insertion of hemodialysis catheter is recommended for vascular access.1Frykholm P. Pikwer A. Hammarskjöld F. et al.Clinical guidelines on central venous catheterisation.Acta Anaesthesiol Scand. 2014; 58: 508-524Crossref PubMed Scopus (132) Google Scholar, 2Lamperti M. Bodenham A.R. Pittiruti M. et al.International evidence-based recommendations on ultrasound-guided vascular access.Intensive Care Med. 2012; 38: 1105-1117Crossref PubMed Scopus (491) Google Scholar, 3Saul T. Doctor M. Kaban N.L. et al.The ultrasound-only central venous catheter placement and confirmation procedure.J Ultrasound Med. 2015; 34: 1301-1306Crossref PubMed Scopus (13) Google Scholar Agitated saline bubble−enhanced ultrasound is efficient and rapid to ensure the correct positioning of central venous cateter in critically ill patients. Delayed appearance of microbubbles in the right atrium4Vezzani A. Brusasco C. Palermo S. et al.Ultrasound localization of central vein catheter and detection of postprocedural pneumothorax: an alternative to chest radiography.Crit Care Med. 2010; 38: 533-538Crossref PubMed Scopus (134) Google Scholar indicates inadequate positioning. A recent retrospective study performed in 202 patients admitted in a dialysis center and undergoing internal jugular catheterization for hemodialysis or medication administration reported that 2 catheter malpositions were detected immediately by agitated saline bubble−enhanced ultrasound.5Wen M. Stock K. Heemann U. et al.Agitated saline bubble-enhanced transthoracic echocardiography: a novel method to visualize the position of central venous catheter.Crit Care Med. 2014; 42: e231-e233Crossref PubMed Scopus (23) Google Scholar The primary aim of this prospective study, which was performed in ventilated, critically ill patients with AKI, was to compare agitated saline bubble−enhanced ultrasound with bedside chest radiography for the confirmation of appropriate positioning of hemodialysis catheter. The secondary aim was to compare agitated saline bubble−enhanced ultrasound and bedside chest radiography completion times. As shown in Figure 1, a total of 99 patients were screened, and 91 were included. Clinical characteristics are shown in Table 1. Vascular accesses were jugular (28 right and 4 left) and subclavian veins (45 right and 14 left). Previous venous cannulation before patients' intensive care unit (ICU) admission, obesity, and proximity of infected abdominal and/or vascular incisions made femoral access impracticable.Table 1Patient characteristicsCharacteristicsAll patients, n = 91Jugular vein, n = 32Subclavian vein, n = 59PPhysiological characteristicsSex male/female (%)57/4363/3754/460.44Age, yr, mean ± SD59 ± 1360 ± 1358 ± 120.45Body mass index, kg/cm25 ± 425 ± 425 ± 40.91SOFA score mean ± SD11 ± 211 ± 211 ± 30.4APACHE II mean ± SD21 ± 621 ± 619 ± 50232Charlson Comorbidity Index (mean ± SD)3.7 ± 1.33.6 ± 1.33.8 ± 1.30.55Outcome dead/alive (%)15/8515/8514/860.78Support of organ failureInvasive mechanical ventilation (%)8571830.5Vasopressor support with norepinephrine (%)8275690.28Admission for medical/surgical disease (%)62/3865/3559/410.55Length of ICU stay (d, mean ± SD)12 ± 311 ± 36 ± 30.6Cause of acute kidney injuryIschemia (%)121990.14Nephrotoxicity (%)119120.7Sepsis (%)3241270.18Multifactorial (%)4531520.05Renal replacement characteristicsUrea level (mmol/l, mean ± SD)174 ± 13174 ± 1.1174 ± 1.90.8Sustained low-efficiency dialysis (%)4331690.44Conventional intermittent hemodialysis (%)2445550.24Continuous venous hemodiafiltration3340600.49Maximal dialysis blood flow (ml/min mean ± SD)228 ± 18227 ± 19228 ± 180.92Insertion catheter attempts1.5 (0.7)1.5 (0.82)1.5 (0.71)0.89APACHE, Acute Physiology and Chronic Health Evaluation; ICU, intensive care unit; SOFA, Sequential Organ Failure Assessment. Open table in a new tab APACHE, Acute Physiology and Chronic Health Evaluation; ICU, intensive care unit; SOFA, Sequential Organ Failure Assessment. Among 84 hemodialysis catheters adequately positioned, 82 were identified by agitated saline bubble−enhanced ultrasound (Figures 2 and 3). All malpositioned hemodialysis catheters were identified by agitated saline bubble−enhanced ultrasound (Figures 4 and 5). The malpositions involved 5 ipsilateral internal jugular veins, 1 axillary vein, and 1 innominate vein. Two hemodialysis catheters adequately positioned were not identified by bubble-enhanced ultrasound. In the first patient, a partial vena cava thrombosis was suspected to interfere with microbubble appearance. In the second patient, a pulmonary artery catheter and a central venous catheter were already present in the superior vena cava, and likely partially obstructed the holes of the hemodialysis catheter.Figure 3Ultrasound showing irruption of microbubbles in the right atrium and ventricle 1.5 seconds after the injection of saline air mixture (red arrow), attesting to the appropriate position of the hemodialysis catheter (black arrow on frontal chest x-ray).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 4(a) Bedside chest radiograph showing the inadequate positioning of the hemodialysis catheter in the ipsilateral right internal jugular vein after catheter insertion in the right subclavian vein (black arrow). (b) Ultrasound subxiphoid view showing right atrium (RA) and ventricle (RV) before the administration of microbubbles through the distal lumen of the catheter. (c) Ultrasound subxiphoid view showing the absence of microbubbles in RA and RV 4 seconds after their flush through the distal lumen of the catheter. Dynamic views can be visualized in Figure 5.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 5Ultrasound showing no irruption of microbubbles in the right atrium (RA) and ventricle (RV) after the injection of saline air mixture (red arrow), attesting to the innappropriate position of the hemodialysis catheter in the right internal jugular vein (white arrow on frontal chest x-ray).View Large Image Figure ViewerDownload Hi-res image Download (PPT) A single intra-atrial position of the hemodialysis catheter was recognized by agitated saline bubble−enhanced ultrasound (Figures 6 and 7). A single pneumothorax was detected by lung ultrasound and confirmed by chest radiograhy. Agitated saline bubble−enhanced ultrasound had a high sensitivity, specificity, and diagnostic accuracy (Table 2), with a κ coeffcient of 0.84.Figure 7Ultrasound showing the presence of microbubbles immediately after the injection of saline air mixture, attesting to the intra-atrial position of the hemodialysis catheter (black arrow on frontal chest x-ray).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Table 2Concordance between agitated saline bubble−enhanced ultrasound and chest radiography for identifying appropriate hemodialysis catheter tip positioningChest x-ray+Chest x-ray−Agitated saline bubble−enhanced ultrasound+820Agitated saline bubble−enhanced ultrasound−27SensitivityaSensitivity = (true positive/[true positive + false negative]). = 98%SpecificitybSpecificity = (true negative/[true negative + false positive]). = 100%Diagnostic accuracycDiagnostic accuracy = ([true positive + true negative]/[true positive + true negative + false positive + false negative). = 98%True positive result denotes correct placement of hemodialysis catheter according to bubble-enhanced ultrasound and chest radiography. True negative result = incorrect placement of hemodialysis catheter according to bubble-enhanced ultrasound and chest radiography. False positive result = correct placement of hemodialysis catheter according to bubble-enhanced ultrasound not confirmed by chest radiography. False negative result = incorrect placement of hemodialysis catheter according to bubble-enhanced ultrasound not confirmed by chest radiography.a Sensitivity = (true positive/[true positive + false negative]).b Specificity = (true negative/[true negative + false positive]).c Diagnostic accuracy = ([true positive + true negative]/[true positive + true negative + false positive + false negative). Open table in a new tab True positive result denotes correct placement of hemodialysis catheter according to bubble-enhanced ultrasound and chest radiography. True negative result = incorrect placement of hemodialysis catheter according to bubble-enhanced ultrasound and chest radiography. False positive result = correct placement of hemodialysis catheter according to bubble-enhanced ultrasound not confirmed by chest radiography. False negative result = incorrect placement of hemodialysis catheter according to bubble-enhanced ultrasound not confirmed by chest radiography. The average time to confirmation of appropriate hemodialysis catheter placement was 10.5 minutes (95% confidence interval = 9.7–11.3 minutes) by bedside agitated saline bubble−enhanced ultrasound and 133.5 minutes (95% confidence interval = 124.1–142.8 minutes) by bedside chest radiography (P < 0.0001). In this prospective study performed in critically ill patients with AKI, agitated saline bubble−enhanced ultrasound was highly accurate in identifying adequate placement of hemodialysis cateter. It was significantly faster than bedside chest radiography. The use of ultrasound guidance for the placement of central venous catheters in critically ill patients is recommended.2Lamperti M. Bodenham A.R. Pittiruti M. et al.International evidence-based recommendations on ultrasound-guided vascular access.Intensive Care Med. 2012; 38: 1105-1117Crossref PubMed Scopus (491) Google Scholar, 3Saul T. Doctor M. Kaban N.L. et al.The ultrasound-only central venous catheter placement and confirmation procedure.J Ultrasound Med. 2015; 34: 1301-1306Crossref PubMed Scopus (13) Google Scholar, 6Liu Y.T. Bahl A. Evaluation of proper above-the-diaphragm central venous catheter placement: the saline flush test.Am J Emerg Med. 2011; 29: 842Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar, 7Ablordeppey E.A. Drewry A.M. Beyer A.B. et al.Diagnostic accuracy of central venous catheter confirmation by bedside ultrasound versus chest radiography in critically ill patients: a systematic review and meta-analysis.Crit Care Med. 2017; 45: 715-724Crossref PubMed Scopus (62) Google Scholar This recommendation applies to critically patients requiring placement of a hemodialysis catheter for grade 3 AKI. Given the presence of a sonographer during catheter insertion, it is logical to use ultrasound for assessing adequate positioning at the end of the procedure. There are 2 contrast-enhanced ultrasound methods for assessing correct positioning of central venous catheters. The first is based on the rapid flush of saline through the catheter.8Lanza C. Russo M. Fabrizzi G. Central venous cannulation: are routine chest radiographs necessary after B-mode and colour Doppler sonography check?.Pediatr Radiol. 2006; 36: 1252-1256Crossref PubMed Scopus (30) Google Scholar Correct positioning is detected as an immediate (≤2-second) echogenic turbulent flow pattern within the right atrium. Color Doppler imaging improves flow turbulence detection.9Weekes A.J. Johnson D.A. Keller S.M. et al.Central vascular catheter placement evaluation using saline flush and bedside echocardiography.Acad Emerg Med. 2014; 21: 65-72Crossref PubMed Scopus (48) Google Scholar Three prospective studies reported a sensitivity of 75% and a specificity of 100% for assessing inappropriate catheter positioning compared to bedside chest radiography.10Gekle R. Dubensky L. Haddad S. et al.Saline flush test: can bedside sonography replace conventional radiography for confirmation of above-the-diaphragm central venous catheter placement?.J Ultrasound Med. 2015; 34: 1295-1299Crossref PubMed Scopus (28) Google Scholar, 11Weekes A.J. Keller S.M. Efune B. et al.Prospective comparison of ultrasound and CXR for confirmation of central vascular catheter placement.Emerg Med J. 2016; 33: 176-180Crossref PubMed Scopus (24) Google Scholar, 12Shieh L. Go M. Gessner D. et al.Improving and sustaining a reduction in iatrogenic pneumothorax through a multifaceted quality-improvement approach.J Hosp Med. 2015; 10: 599-607Crossref PubMed Scopus (9) Google Scholar The second method, based on the rapid flush of a saline−air mixture through the inserted catheter, is more sensitive.4Vezzani A. Brusasco C. Palermo S. et al.Ultrasound localization of central vein catheter and detection of postprocedural pneumothorax: an alternative to chest radiography.Crit Care Med. 2010; 38: 533-538Crossref PubMed Scopus (134) Google Scholar, 5Wen M. Stock K. Heemann U. et al.Agitated saline bubble-enhanced transthoracic echocardiography: a novel method to visualize the position of central venous catheter.Crit Care Med. 2014; 42: e231-e233Crossref PubMed Scopus (23) Google Scholar Correct catheter positioning is detected as the appearance within 2 seconds of multiple micobubbles in the right atrium. Incorrect positioning is detected as the lack of or delayed appearance of these microbubbles. The present study confirms the high sensitivity (99%) and specificity (100%) of the technique for assessing appropriate hemodialysis catheter placement. In addition to easy implementation, agitated saline bubble−enhanced ultrasound avoids radiation exposure for patients and health care workers, and reduces time delay to catheter use. Adequate positioning is required to obtain an appropriate blood flow allowing efficient dialysis. In our study, the blood flow rate was considered adequate in every patient (>200 ml/min) after repositioning the 7 malpositioned catheters. Transthoracic lung ultrasound can also accurately detect pneumothorax complicating hemodialysis catheter insertion, questioning the use of routine postprocedure bedside chest radiography.13Hourmozdi J.J. Markin A. Johnson B. et al.Routine chest radiography is not necessary after ultrasound-guided right internal jugular vein catheterization.Crit Care Med. 2016; 44: e804-e808Crossref PubMed Scopus (30) Google Scholar Our study has several limitations. First, it is an observational single-center study. Second, only hemodialysis catheter positioned in the right atrium could be directly visualized using the subxiphoid 4-chamber view. In fact, the majority of malpositioned catheters are located in the contralateral subclavian vein and/or ipsilateral internal jugular vein.4Vezzani A. Brusasco C. Palermo S. et al.Ultrasound localization of central vein catheter and detection of postprocedural pneumothorax: an alternative to chest radiography.Crit Care Med. 2010; 38: 533-538Crossref PubMed Scopus (134) Google Scholar The internal jugular vein can be visualized by ultrasound using short- and long-axis neck planes, whereas the subclavian vein can be visualized using short- and long-axis supra- and infraclavicular approaches.3Saul T. Doctor M. Kaban N.L. et al.The ultrasound-only central venous catheter placement and confirmation procedure.J Ultrasound Med. 2015; 34: 1301-1306Crossref PubMed Scopus (13) Google Scholar, 14Auyong D.B. Yuan S.C. Rymer N.A. et al.A randomized crossover study comparing a novel needle guidance technology for simulated internal jugular vein cannulation.Anesthesiology. 2015; 123: 535-541Crossref PubMed Scopus (16) Google Scholar Therefore, if, at the end of the procedure, agitated saline bubble−enhanced ultrasound results are negative without evidence of intra-atrial positioning of the catheter tip, then ultrasound examination of subclavian and internal jugular veins that were not punctured should be performed to detect the presence of the catheter. In conclusion, the dynamic ultrasound visualization of microbubbles in the right atrium was highly accurate to identify adequate placement of hemodialysis central venous catheters and significantly faster than bedside chest radiography. It allowed the immediate start of renal replacement therapy, thereby expediting patient care. All the authors declared no competing interests.