The efficacy of sonographic measurement of inferior vena cava diameter as an estimate of central venous pressure

Transcription

1 Ciozd et l. Crdiovsculr Ultrsound (2016) 14:33 DOI /s REVIEW Open Access The efficcy of sonogrphic mesurement of inferior ven cv dimeter s n estimte of centrl venous pressure Willim Ciozd 1, Iln Kedn 2, Devin W. Kehl 3*, Rymond Zimmer 2, Rj Khndwll 2 nd Asher Kimchi 3 Astrct Bckground: Centrl venous pressure (CVP) nd right tril pressure (RAP) re importnt prmeters in the complete hemodynmic ssessment of ptient. Sonogrphic mesurement of the inferior ven cv (IVC) dimeter is non-invsive method of estimting these prmeters, ut there re limited dt summrizing its dignostic ccurcy cross multiple studies. We performed comprehensive review of the existing literture to exmine the dignostic ccurcy nd clinicl utility of sonogrphic mesurement of IVC dimeter s method for ssessing CVP nd RAP. Methods: We performed systemtic serch using PuMed of clinicl studies compring sonogrphic evlution of IVC dimeter nd collpsiility ginst gold stndrd mesurements of CVP nd RAP. We included clinicl studies tht were performed in dults, used current imging techniques, nd were pulished in English. Results: Twenty one clinicl studies were identified tht compred sonogrphic ssessment of IVC dimeter with CVP nd RAP nd met ll inclusion criteri. Despite sustntil heterogeneity in mesurement techniques nd ptient popultions, most studies demonstrted moderte strength correltions etween mesurements of IVC dimeter nd collpsiility nd CVP or RAP, ut more fvorle dignostic ccurcy using pre-specified cut points. Findings were inconsistent mong mechniclly ventilted ptients, except in the sence of positive end-expirtory pressure. Conclusion: Sonogrphic mesurement of IVC dimeter nd collpsiility is vlid method of estimting CVP nd RAP. Given the ese, sfety, nd vilility of this non-invsive technique, roder doption nd ppliction of this method in clinicl settings is wrrnted. Keywords: Inferior ven cv, Centrl venous pressure, Right tril pressure, Ultrsound Bckground Mesurement of centrl venous pressure (CVP) is criticl component of the complete hemodynmic ssessment of ptient. CVP is considered equivlent to right tril pressure (RAP) when the ven cv is continuous with the right trium [1]. Centrl venous ctheteriztion is the gold stndrd mesurement of CVP nd RAP [1]. However, widespred nd routine use of this invsive procedure re limited y the risk of complictions, including infection, ctheter-induced thromosis, nd rrhythmis [2]. Therefore, noninvsive techniques to estimte CVP ply crucil role in promoting more widespred CVP evlution in clinicl prctice [1]. * Correspondence: Devin.Kehl@cshs.org 3 Cedrs-Sini Hert Institute, Los Angeles, CA, USA Full list of uthor informtion is ville t the end of the rticle The inferior ven cv (IVC) is complint vessel whose size nd shpe vry with chnges in CVP nd intrvsculr volume [1]. Therefore, sonogrphic mesurement of the IVC represents n effective nd noninvsive method of estimting CVP [3, 4]. However, severl fctors my ffect IVC size. Under norml physiologic conditions, IVC dimeter decreses nd venous return increses during inspirtion due to negtive intrthorcic pressure nd positive intr-dominl pressure [5]. IVC dimeter lso decreses during ventriculr systole [1]. Additionlly, ptient position my ffect IVC dimeter, s the dimeter is smllest when the ptient is in the left lterl position nd lrgest when the ptient is in the right lterl position [6]. Awreness of these vriles is criticl to the ccurte collection nd interprettion of sonogrphic IVC mesurements The Author(s). Open Access This rticle is distriuted under the terms of the Cretive Commons Attriution 4.0 Interntionl License ( which permits unrestricted use, distriution, nd reproduction in ny medium, provided you give pproprite credit to the originl uthor(s) nd the source, provide link to the Cretive Commons license, nd indicte if chnges were mde. The Cretive Commons Pulic Domin Dediction wiver ( pplies to the dt mde ville in this rticle, unless otherwise stted.

2 Ciozd et l. Crdiovsculr Ultrsound (2016) 14:33 Pge 2 of 8 Erly stndrds for sonogrphic IVC ssessment clled for mesurements of the mximum IVC dimeter (IVCmx) nd the minimum IVC dimeter (IVCmin) during the respirtory cycle [5]. An IVC collpsiility index (IVCCI), which correltes with RAP nd CVP, cn e clculted with the following formul: (IVCmx IVCmin)/IVCmx [3]. Guidelines on echocrdiogrphic chmer quntifiction pulished in 2015 from the Americn Society of Echocrdiogrphy recommend tht the mximum IVC dimeter e mesured from the sucostl view with the IVC displyed long its long xis [7]. The dimeter should e mesured immeditely cudl to the junction of the heptic vein with the IVC nd pproximtely 1 2 cm cudl to the junction of the IVC nd the ostium of the right trium [7]. Although prior itertions of these guidelines hve recommended these mesurements e performed with the ptient in the left lterl position [8] nd t the end of expirtion [9], the supine position is now recommended, nd currently no specific recommendtion is mde s to the phse of the respirtory cycle during which to perform the mesurement. Mesurement of the IVCCI with rief sniff is lso recommended in comintion with IVC dimeter in order to estimte CVP s norml (0 5 mmhg), intermedite (5 10 mmhg), or high (10 20 mmhg) [7]. A numer of clinicl studies hve evluted IVC dimeter mesurements s method to estimte CVP nd RAP, ut the overll reliility nd ccurcy of this technique hs not een systemiclly compred cross multiple studies. We providecomprehensive review of the existing literture to exmine the reliility nd ccurcy of sonogrphic mesurement of IVC dimeter s method for ssessing CVP nd RAP. Methods We performed systemtic literture serch in PuMed with serch terms ultrsound of inferior ven cv nd centrl venous pressure nd ultrsound of inferior ven cv nd right tril pressure to identify clinicl studies tht compred ultrsound mesurement of IVC dimeter nd collpsiility ginst gold stndrd mesurements of CVP nd RAP. Only clinicl reserch studies mong dults tht pertined to our ojective, used up-to-dte imging techniques, nd were pulished in English were included in our review. For ech study, we collected dt on study design, ptient popultion, nd mjor findings, including the correltion etween invsive pressure mesurements nd IVC mesurement prmeters. Results Our literture serch returned 214 journl rticles, of which we excluded 13 studies tht were performed in peditric/fetl popultions, 13 tht were not clinicl reserch studies, 149 tht were unrelted to our ojective, 17 tht were not pulished in English, nd 1 tht used n osolete imging technique (Fig. 1). A totl of 21 studies tht exmined the correltion etween sonogrphic mesurements of IVC dimeter nd CVP or RAP were reviewed. The smple sizes cross studies rnged from 22 to 175 ptients, with totl of 1,430 ptients cross ll studies comined. In ll studies, IVC mesurements were tken from the supine position, using the sucostl view (Tle 1). However, there were sustntil differences etween the studies in terms of the ptient popultion, use of mechnicl ventiltion with positive end-expirtory pressure (PEEP), men CVP or RAP, nd method of IVC dimeter mesurement. Furthermore, the specific IVC mesurement Fig. 1 Study selection flowchrt showing the structure of the PuMed serch nd exclusion criteri

3 Tle 1 Methodology nd smple descriptions for studies exmining IVC dimeter s n estimte of CVP or RAP Authors Yer N Ptient popultion Percent on mechnicl ventiltion PEEP (cm H 2 O) Gold stndrd comprison Men CVP or RAP Ptient position Sonogrpher Other notes Tniguchi et l. [19] Elective right hert ctheteriztion 0 % n/ RAP 8 mmhg Supine Sonogrpher 9 % post-hert trnsplnt Soczyk et l. [24] Elective crdic surgery 100 % 4.5 CVP 6.7 mmhg Supine Sonogrpher Tsutsui et l. [22] Decompensted hert filure 0 % n/ RAP 13 mmhg Supine Sonogrpher Zhng et l. [21] Gstrointestinl surgery with hypovolemi 0 % n/ CVP 3 mmhg Supine Sonogrpher Repeted fter fluids Citilcioglu et l. [25] ER ptients with invsive monitor 24 % 5 CVP 7.7 mmhg (8.7 mmhg with mechnicl ventiltion) Supine Prekker et l. [26] Medicl ICU ptients 0 % n/ CVP 7 mmhg (medin) Supine MD in IM, ICU, ER De Lorenzo et l. [27] ER nd ICU ptients with criticl illness 43 % CVP 10.4 cmh 2 O Supine ER MD or RN, ICU MD Suxiphoid views in 57 ptients Ptel et l. [16] Decompensted hert filure 0 % n/ RAP 11 mmhg Supine Sonogrpher 20 % moderte TR 8 % severe TR 25 % AF Yildirimturk et l. [15] Rheumtic mitrl stenosis 0 % n/ RAP 9.7 mmhg Supine Sonogrpher 44 % in AF Ngdev et l. [28] Criticl ER ptients with centrl ctheter 19 % CVP 10.5 mmhg Supine ER MD Schefold et l. [29] Severe sepsis, septic shock 100 % 12 CVP 15 cmh 2 O Supine ICU MD Arthur et l. [10] Elective crdic surgery 100 % 0; ventiltor CVP 14.5 mmhg Supine Anesthesi MD TEE only turned off Lorsomrdee et l. [11] Elective crdic surgery 100 % 0, 5, 10 CVP 11, 12, 14 mmhg Supine Anesthesi MD TEE only Brennn et l. [18] Elective right hert ctheteriztion 0 % n/ RAP 7 mmhg Supine Sonogrpher 9 % in AF 30 % post-hert trnsplnt Ommen et l. [30] Crdic ctheteriztion l 0 % n/ RAP Supine Ngueh et l. [31] Elective right hert ctheteriztion or criticl 34 % illness Jue et l. [12] ICU or CCU 100 % Kircher et l. [3] Crdic ctheteriztion l 0 % n/ RAP 11 mmhg Simonson et l. [32] Awke ptients with pulmonry rteril ctheters 0 % n/ RAP Moreno et l. [17] helthy volunteers; 95 with crdic normlities; 65 with right hert ctheteriztion Mintz et l. [20] Elective right hert ctheteriztion 0 % n/ RAP dt not ville RAP 9 mmhg Supine Sonogrpher RAP 0 % n/ RAP >7 mmhg in 35/65 ptients Supine Sonogrpher Sonogrpher 17 % in AF Supine Sonogrpher BSA djusted Ciozd et l. Crdiovsculr Ultrsound (2016) 14:33 Pge 3 of 8

4 Ciozd et l. Crdiovsculr Ultrsound (2016) 14:33 Pge 4 of 8 prmeters vried cross studies. These included IVCmx, mximum IVC dimeter t end-expirtion (IVCe), mximum IVC dimeter t end-inspirtion (IVCi), nd IVCCI. All studies reported correltions etween IVC mesurements nd direct invsive mesurements of CVP or RAP. The mjority of studies reported sttisticlly significnt positive correltions etween sonogrphic mesurements of IVC dimeter nd CVP or RAP. All studies tht exmined the reltionship etween ultrsound mesurements of mximum IVC dimeter nd CVP or RAP cross the entire respirtory cycle, t end-expirtion, or t end-inspirtion reported positive correltions (Tle 2). All studies tht provided p-vlues for the correltion reported sttisticlly significnt results t α =0.05. Multiple studies lso reported sttisticlly significnt negtive correltions etween IVCCI nd CVP or RAP (Tle 3). Although some studies mesured IVCCI during pssive inspirtion while others mesured it during forceful inspirtion (sniff), neither method hd consistently stronger correltion with invsive CVP or RAP mesurements. Severl studies hve lso identified threshold levels of IVC size nd collpsiility y which to estimte CVP or RAP (Tle 4). Although the specific threshold vlues for IVC size, IVCCI, CVP, nd RAP vried slightly cross studies, the dignostic ccurcy of IVC mesurements prmeters ws generlly high, with the C-sttistic rnging from for IVC dimeter nd for IVCCI. The reported correltions etween IVC dimension nd CVP in mechniclly ventilted ptients re generlly wek nd inconsistent cross studies (Tle 5). Approximtely hlf of the studies in this ptient popultion did not detect sttisticlly significnt correltion. Correltions tht did rech sttisticl significnce in mechniclly ventilted ptients were mostly wek to moderte in strength. The notle exceptions were the two studies in which no PEEP ws used during ventiltion, with correltion coefficients Tle 2 Pulished correltions etween ultrsound mesurements of mximum IVC nd CVP or RAP mong spontneously ventilting ptients Mesurement time-point Study N Men CVP or RAP Correltion coefficient p-vlue Comments Entire respirtory cycle Tniguchi et l., [19] <0.05 Yildirimturk et l., [15] <0.005 Ptients with norml sinus rhythm only; When ll ptients (n = 39) included, r = 0.51 (p < 0.005). Ptel et l., [16] <0.001 Brennn et l., [18] Ommen et l., [30] 71 Moreno et l., [17] <0.001 End-expirtion Citilcioglu et l., [25] Tsutsui et l., [22] < Zhng et l., [21] <0.01 Prekker et l., [26] <0.05 Study reports medin CVP/RAP De Lorenzo et l., [27] < % of ptient received mechnicl ventiltion Ngdev et l., [28] < % of ptients received mechnicl ventiltion Ngueh et l., [31] Kircher et l., [3] Mintz et l., [20] <0.001 End-inspirtion Citilcioglu et l., [25] Tsutsui et l., [22] < minimum dimeter during sniff De Lorenzo et l., [27] <0.05 extrpolted from dt provided Ngdev et l., [28] <0.05 Kircher et l., [3] dt not ville Simonson et l., [32] 27 Simonson et l., [32] minimum dimeter during inspirtion

5 Ciozd et l. Crdiovsculr Ultrsound (2016) 14:33 Pge 5 of 8 Tle 3 Pulished correltions etween ultrsound mesurements of IVC collpsiility index nd CVP or RAP in spontneously ventilting ptients Type of inspirtion Study N Men CVP or RAP Correltion coefficient p-vlue Comments Pssive Tniguchi et l., [19] <0.05 Study reports medin CVP/RAP Zhng et l., [21] Prekker et l., [26] <0.05 Study reports medin CVP/RAP Yildirimturk et l., [15] <0.05 Ngdev et l., [28] <0.05 Brennn et l., [18] Kircher et l., [3] 83 Moreno et l., [17] 65 Sniff Tniguchi et l., [19] <0.05 Study reports medin CVP/RAP Tsutsui et l., [22] < Ptel et l., [16] Brennn et l., [18] dt not ville Ngueh et l., [31] <0.001 of 0.80 nd 0.86 for the reltionship etween IVCe nd CVP or RAP [10, 11]. Discussion Overll, these findings support the use of sonogrphic mesurements of IVC dimeter to estimte CVP or RAP in spontneously ventilting ptients. Positive correltions were consistently reported etween IVC size nd CVP or RAP, nd negtive correltions were consistently reported etween IVCCI nd CVP or RAP. Although the correltions were generlly only modertely strong, the dignostic performnce of pre-specified cut-points Tle 4 Dignostic performnce chrcteristics of IVC size prmeters for the prediction of CVP or RAP mong spontneously ventilting ptients Prmeter Study N Prmeter cut-point IVCmx Tniguchi et l., [19] cm RAP 10 mmhg Outcome Sensitivity Specificity Positive predictive vlue Negtive predictive vlue Prekker et l., [26] 65 <2.0 cm CVP < 10 mmhg Ptel et l., [16] cm RAP > 10 mmhg Brennn et l., [18] 46 >2.0 cm RAP > 10 mmhg Moreno et l., [17] 65 >2.3 cm RAP > 7 mmhg IVCCI (pssive) Tniguchi et l., [19] 90 <25 % RAP 10 mmhg Prekker et l., [26] 65 >50 % CVP < 10 mmhg Ptel et l., [16] 40 <40 % RAP > 10 mmhg 0.67 Ngdev et l., [28] 73 >50 % CVP < 8 mmhg Brennn et l., [18] 46 <20 % RAP > 10 mmhg Moreno et l., [17] 65 <40 % RAP > 7 mmhg IVCCI (sniff) Tniguchi et l., [19] 90 <50 % RAP 10 mmhg IVCmx nd IVCCI (pssive) Brennn et l., [18] 46 <40 % RAP > 10 mmhg Ngueh et l., [31] 23 <50 % RAP > 8 mmhg Kircher et l., [3] 83 <50 % RAP > 10 mmhg Ptel et l., [16] cm nd <40 % Ptel et l., [16] cm nd <40 % Sttisticlly significnt t lph = 0.05 dt not ville RAP > 15 mmhg RAP > 10 mmhg Are under ROC curve

6 Ciozd et l. Crdiovsculr Ultrsound (2016) 14:33 Pge 6 of 8 Tle 5 Pulished correltions etween ultrsound mesurements of IVC dimeter nd CVP or RAP mong mechniclly ventilted ptients Prmeter Study N Men CVP or RAP (mmhg) PEEP (cm H 2 O) Correltion coefficient p-vlue IVCmx Soczyk et l., [24] Ngueh et l., [31] * 0.4 NS IVCe Citilcioglu et l., [25] * NS Schefold et l., [29] Arthur et l., [10] < Lorsomrdee et l., [11] <0.001 Lorsomrdee et l., [11] NS Jue et l., [12] 49 * * Citilcioglu et l., [25] * NS De Lorenzo et l., [27] * 0.26 NS IVCi Schefold et l., [29] Soczyk et l., [24] Ngueh et l., [31] * 0.24 NS IVCCI Jue et l., [12] 49 * * 0.13 NS Ngueh et l., [31] * 0.24 NS Jue et l., [12] 49 * * 0.13 NS cm H 2 O extrpolted from dt provided *dt not ville ws superior, nd justifies the current guideline recommendtions for estimtion of right-sided filling pressure. Importntly, there ws sustntil heterogeneity cross the studies reviewed in the timing of IVC size mesurement with respect to the respirtory cycle. Although IVCe hs previously een recommended s the preferred IVC prmeter y which to estimte CVP or RAP [9], the strength of the correltions etween CVP nd IVCe, IVCi, nd IVCmx were similr. This is reflected in the most recent guidelines y the Americn Society of Echocrdiogrphy, which do not specify n optiml phse of the respirtory cycle during which to mesure the mximl IVC dimeter. The correltions etween IVC dimension nd CVP in mechniclly ventilted ptients were generlly wek nd inconsistently oserved. Furthermore, the use nd mgnitude of PEEP vried gretly cross studies of mechniclly ventilted ptients. Positive pressure ventiltion leds to incresed intrthorcic pressure, decresed systemic venous return, nd incresed volume of venous lood in the IVC. The dimension nd distensiility of the IVC is consequently ffected. Therefore, the use of IVC mesurements to estimte RAP in mechniclly ventilted ptients is usully unrelile. Accordingly, 2015 guidelines from the Americn Society of Echocrdiogrphy recommend ginst their routine ppliction in this setting [7]. However, in the study y Jue nd collegues, despite only modest correltion etween RAP nd IVC dimension, these uthors did find tht n IVC dimeter of 1.2 cm or less hd 100 % specificity for right tril pressure less thn 10mmHg, leit with poor sensitivity (25 %) [12]. Therefore, smll IVC in the setting of mechnicl ventiltion my still point towrd the sence of elevted RAP. In ddition, the correltion of IVCe nd RAP my still e vlid in the sence of PEEP. There re few other notle circumstnces in which IVC dimeter my not correlte with CVP or RAP. First, the IVC my e dilted in young elite thletes with norml RAP, prticulrly swimmers. One study showed men IVC dimeter of 2.3 cm in elite thletes compred to 1.3 cm in control sujects [13]. In ddition, young ptients with vsovgl syncope ut no other crdic history hve een found to hve incresed IVC size s compred to controls, suggestive tht venous pooling in young helthy ptients my increse IVC size independent of ny increse in tril pressure [14]. Furthermore, the CVP or RAP cn e highly dynmic, such s in the setting of severe tricuspid regurgittion, nd IVC size should not e relied upon s n ccurte estimte in this setting. Finlly, invsive mesurement of the CVP or RAP is lso suject to its own pitflls nd mesurement error. These cn e numerous, nd with ccurte mesurements eing dependent on proper ctheter function nd pressure trnsduction, leveling, nd tip positioning. There ws sustntil heterogeneity cross the reviewed studies with respect to ptient popultion. Importntly, the vlidity of IVC mesurements for CVP or RAP estimtion my not e equivlent in ll ptient sugroups. One

7 Ciozd et l. Crdiovsculr Ultrsound (2016) 14:33 Pge 7 of 8 popultion with limited dt includes ptients with tril firilltion, in whom venous inflow Doppler pttern is ltered due to the loss of the tril relxtion wve. Only four studies included ptients with tril firilltion [15 18], with such ptients comprising minority of the popultion in ech study. None of these studies ssessed the vlidity of these mesurements specificlly mong ptients with tril firilltion. Further investigtion is wrrnted in these ptients. Ptients with history of hert trnsplnttion, included in severl of the studies descried in this review, represent nother sugroup worthy of dditionl reserch. Whether mechnicl disruption of the IVC with cvl nstomosis ffects its performnce s n indictor of RAP hs not een descried, ut could e cliniclly importnt. There re only limited dt suggesting n effect of ody size on IVC dimeter [19], nd to support indexing IVC dimeter to ody surfce re (BSA) for the estimtion of RAP. A study from 1981 oserved wek correltion of indexed IVC dimeter with RAP [20], nd more contemporry study showed no improvement in dignostic performnce of IVC mesurements s n estimte of RAP with indexing to BSA [18]. A study from 2015 showed no improvement in dignostic performnce fter indexing IVC dimeter to BSA, ut found significntly lower optiml cut point for IVC dimeter in the estimtion of RAP mong ptients with smll BSA [19]. Guideline recommendtions currently do not recommend indexing IVC size to BSA. One vlule ppliction of non-invsive sonogrphic estimtion of CVP my lie in seril mesurements. IVC dimeter hs een shown to increse fter fluid resuscittion nd in ssocition with concomitnt increses in CVP [21]. Additionlly, lthough the precision of IVCderived estimtion of CVP my e reduced in hert filure, seril ssessment cn e performed in ptients with decompensted hert filure in order to guide mngement [22]. This simple prmeter, esily mesurle t the point of cre, hs een found to offer s much precision s more complex estimtes involving more vriles [22]. Simplifiction of IVC mesurements could improve their stndrdiztion nd ppliction in clinicl prctice. In pilot study, Mrtin et l. demonstrted success in trining hospitlists to perform sonogrphic IVC mesurements using n online module nd 1-dy trining session [23]. After the session, 8 of 10 hospitlists were le to ccurtely cquire nd interpret IVC imges in 5 of 5 ptients nd discern whether the IVCCI ws greter thn 50 % with 91 % ccurcy. The success of this short trining progrm not only exemplifies the ese of oth IVC ultrsound trining nd use ut lso model y which it could e pplied more rodly. Conclusion Ultrsound mesurement of the IVC t the point of cre provides insight into hemodynmics in rpid nd noninvsive mnner nd cn impct clinicl decision mking. Assessment of CVP, historiclly requiring invsive intervention, cn e performed non-invsively with resonle ccurcy in most, ut not ll, clinicl settings. Additionl vlidtion of IVC mesurements for estimtion of CVP my e indicted in specific sugroups of ptients. Mesurement of the IVC with portle ultrsound devices s well s dditionl helth cre provider trining my llow for expnsion of filling pressure estimtion s n extension of the routine edside clinicl exmintion of ll ptients. Arevitions AF, tril firilltion; BSA, ody surfce re; CCU, criticl cre unit; CVP, centrl venous pressure; ER, emergency room; ICU, intensive cre unit; IM, internl medicine; IVC, inferior ven cv; IVCCI, inferior ven cv collpsiility index; IVCe, mximum dimeter of the inferior ven cv t end-expirtion; IVCi, mximum dimeter of the inferior ven cv t endinspirtion; IVCmx, mximum dimeter of the inferior ven cv cross the respirtory cycle; MD, medicl doctor; N, smple size; n/, not pplicle; PEEP, positive end-expirtory pressure; RAP, right tril pressure; RN, registered nurse; ROC, receiver operting chrcteristic; TEE, trnsesophgel echocrdiogrm; TR, tricuspid regurgittion. Acknowledgements The uthors would like to thnk Dr. Mdhuri Sudn for her review nd editing of this work in preprtion for puliction. Funding This study ws supported y The Shekels Chritle Foundtion. The funding ody hd no influence on the study design or conduct. Avilility of dt nd mterils Not pplicle. No dt were used in this study, nd ll rticles reviewed in this mnuscript re ville online from their respective pulishers. Authors contriutions WL nd DK performed the literture review, compiled the dt, nd drfted the mnuscript. IK conceived of the study design, provided project oversight, nd edited the mnuscript. RZ nd RK edited the mnuscript. AK conceived of the study design nd provided project oversight. All uthors red nd pproved the finl mnuscript. Competing interests The uthors declre tht they hve no competing interests. Consent for puliction No consent for puliction to disclose. Ethics pprovl nd consent to prticipte Need for pprovl ws wived. Author detils 1 Dvid Geffen School of Medicine, University of Cliforni, Los Angeles, CA, USA. 2 Cedrs-Sini Hert Institute, Cedrs-Sini Medicl Group, Beverly Hills, CA, USA. 3 Cedrs-Sini Hert Institute, Los Angeles, CA, USA. Received: 8 July 2016 Accepted: 7 August 2016 References 1. Beigel R, Cercek B, Luo H, Siegel RJ. Noninvsive evlution of right tril pressure. J Am Soc Echocrdiogr. 2013;26:

8 Ciozd et l. Crdiovsculr Ultrsound (2016) 14:33 Pge 8 of 8 2. Kido DK, King PD, Mnzione JV, Simon JH. The role of ctheters nd guidewires in the production of ngiogrphic thromoemolic complictions. Investig Rdiol. 1988;23 Suppl 2:S Kircher BJ, Himelmn RB, Schiller NB. Noninvsive estimtion of right tril pressure from the inspirtory collpse of the inferior ven cv. Am J Crdiol. 1990;66: Bodson L, Vieillrd-Bron A. Respirtory vrition in inferior ven cv dimeter: surrogte of centrl venous pressure or prmeter of fluid responsiveness? Let the physiology reply. Crit Cre. 2012;16: Ntori H, Tmki S, Kir S. Ultrsonogrphic evlution of ventiltory effect on inferior ven cvl configurtion. Am Rev Respir Dis. 1979; 120: Nko S, Come PC, McKy RG, Rnsil BJ. Effects of positionl chnges on inferior ven cvl size nd dynmics nd correltions with right-sided crdic pressure. Am J Crdiol. 1987;59: Lng RM, Bdno LP, Mor-Avi V, Afillo J, Armstrong A, Ernnde L, et l. Recommendtions for crdic chmer quntifiction y echocrdiogrphy in dults: n updte from the Americn Society of Echocrdiogrphy nd the Europen Assocition of Crdiovsculr Imging. J Am Soc Echocrdiogr. 2015;28: Lng RM, Bierig M, Devereux RB, Flchskmpf FA, Foster E, Pellikk PA, et l. Recommendtions for chmer quntifiction: report from the Americn Society of Echocrdiogrphy s Guidelines nd Stndrds Committee nd the Chmer Quntifiction Writing Group, developed in conjunction with the Europen Assocition of Echocrdiogrphy, rnch of the Europen Society of Crdiology. J Am Soc Echocrdiogr. 2005;18: Rudski LG, Li WW, Afillo J, Hu L, Hndschumcher MD, Chndrsekrn K, et l. Guidelines for the echocrdiogrphic ssessment of the right hert in dults: report from the Americn Society of Echocrdiogrphy endorsed y the Europen Assocition of Echocrdiogrphy, registered rnch of the Europen Society of Crdiology, nd the Cndin Society of Echocrdiogrphy. J Am Soc Echocrdiogr. 2010;23: Arthur ME, Lndolfo C, Wde M, Cstresn MR. Inferior ven cv dimeter (IVCD) mesured with trnsesophgel echocrdiogrphy (TEE) cn e used to derive the centrl venous pressure (CVP) in nesthetized mechniclly ventilted ptients. Echocrdiogrphy. 2009;26: Lorsomrdee S, Lorsomrdee S, Cromheecke S, ten Broecke PW, De Hert SG. Inferior ven cv dimeter nd centrl venous pressure correltion during crdic surgery. J Crdiothorc Vsc Anesth. 2007;21: Jue J, Chung W, Schiller NB. Does inferior ven cv size predict right tril pressures in ptients receiving mechnicl ventiltion? J Am Soc Echocrdiogr. 1992;5: Goldhmmer E, Mesnick N, Ainder EG, Sgiv M. Dilted inferior ven cv: common echocrdiogrphic finding in highly trined elite thletes. J Am Soc Echocrdiogr. 1999;12: Styczynski G, Jltuszewsk M, Kosiorowsk N, Kostrzewsk M, Szmigielski C. Dilted inferior ven cv in young dults with vsovgl syncope. Arch Intern Med. 2009;169: Yildirimturk O, Tyyreci Y, Erdim R, Ozen E, Yurdkul S, Aytekin V, et l. Assessment of right tril pressure using echocrdiogrphy nd correltion with ctheteriztion. J Clin Ultrsound. 2011;39: Ptel AR, Alsheikh-Ali AA, Mukherjee J, Evngelist A, Qurini D, Ordwy LJ, et l. 3D echocrdiogrphy to evlute right tril pressure in cutely decompensted hert filure correltion with invsive hemodynmics. JACC Crdiovsc imging. 2011;4: Moreno FL, Hgn AD, Holmen JR, Pryor TA, Stricklnd RD, Cstle CH. Evlution of size nd dynmics of the inferior ven cv s n index of right-sided crdic function. Am J Crdiol. 1984;53: Brennn JM, Blir JE, Goonewrden S, Ronn A, Shh D, Vsiwl S, et l. Repprisl of the use of inferior ven cv for estimting right tril pressure. J Am Soc Echocrdiogr. 2007;20: Tniguchi T, Ohtni T, Nktni S, Hyshi K, Ymguchi O, Komuro I, et l. Impct of Body Size on Inferior Ven Cv Prmeters for Estimting Right Atril Pressure: A Need for Stndrdiztion? J Am Soc Echocrdiogr. 2015;28: Mintz GS, Kotler MN, Prry WR, Iskndrin AS, Kne SA. Rel-time inferior ven cvl ultrsonogrphy: norml nd norml findings nd its use in ssessing right-hert function. Circultion. 1981;64: Zhng X, Lun H, Zhu P, Feng J, Cui J, Zho Z. Does ultrsonogrphic mesurement of the inferior ven cv dimeter correlte with centrl venous pressure in the ssessment of intrvsculr volume in ptients undergoing gstrointestinl surgery? J Surg Res. 2014;191: Tsutsui RS, Borowski A, Tng WH, Thoms JD, Popovic ZB. Precision of echocrdiogrphic estimtes of right tril pressure in ptients with cute decompensted hert filure. J Am Soc Echocrdiogr. 2014;27: e Mrtin LD, Ziegelstein RC, Howell EE, Mrtire C, Hellmnn DB, Hirsch GA. Hospitlists ility to use hnd-crried ultrsound for centrl venous pressure estimtion fter rief trining intervention: pilot study. J Hosp Med. 2013;8: Soczyk D, Nycz K, Andruszkiewicz P. Bedside ultrsonogrphic mesurement of the inferior ven cv fils to predict fluid responsiveness in the first 6 h fter crdic surgery: prospective cse series oservtionl study. J Crdiothorc Vsc Anesth. 2015;29: Citilcioglu S, See A, Ay MO, Icme F, Avci A, Gulen M, et l. The reltionship etween inferior ven cv dimeter mesured y edside ultrsonogrphy nd centrl venous pressure vlue. Pk J Med Sci. 2014;30: Prekker ME, Scott NL, Hrt D, Sprenkle MD, Lethermn JW. Point-of-cre ultrsound to estimte centrl venous pressure: comprison of three techniques. Crit Cre Med. 2013;41: De Lorenzo RA, Morris MJ, Willims JB, Hley TF, Stright TM, Holrook- Emmons VL, et l. Does simple edside sonogrphic mesurement of the inferior ven cv correlte to centrl venous pressure? J Emerg Med. 2012; 42: Ngdev AD, Merchnt RC, Tirdo-Gonzlez A, Sisson CA, Murphy MC. Emergency deprtment edside ultrsonogrphic mesurement of the cvl index for noninvsive determintion of low centrl venous pressure. Ann Emerg Med. 2010;55: Schefold JC, Storm C, Bercker S, Pschowski R, Oppert M, Kruger A, et l. Inferior ven cv dimeter correltes with invsive hemodynmic mesures in mechniclly ventilted intensive cre unit ptients with sepsis. J Emerg Med. 2010;38: Ommen SR, Nishimur RA, Hurrell DG, Klrich KW. Assessment of right tril pressure with 2-dimensionl nd Doppler echocrdiogrphy: simultneous ctheteriztion nd echocrdiogrphic study. Myo Clin Proc. 2000;75: Ngueh SF, Kopelen HA, Zoghi WA. Reltion of men right tril pressure to echocrdiogrphic nd Doppler prmeters of right tril nd right ventriculr function. Circultion. 1996;93: Simonson JS, Schiller NB. Sonospirometry: new method for noninvsive estimtion of men right tril pressure sed on two-dimensionl echogrphic mesurements of the inferior ven cv during mesured inspirtion. J Am Coll Crdiol. 1988;11: Sumit your next mnuscript to BioMed Centrl nd we will help you t every step: We ccept pre-sumission inquiries Our selector tool helps you to find the most relevnt journl We provide round the clock customer support Convenient online sumission Thorough peer review Inclusion in PuMed nd ll mjor indexing services Mximum visiility for your reserch Sumit your mnuscript t