title: The feasibility and applications of non-invasive cardiac output monitoring, thromboelastography and transit-time flow measurement in living-related renal transplantation surgery: results of a prospective pilot observational study.
abstract: BACKGROUND
  Delayed graft function (DGF) remains a significant and detrimental postoperative phenomenon following living-related renal allograft transplantation, with a published incidence of up to 15%. Early therapeutic vasodilatory interventions have been shown to improve DGF, and modifications to immunosuppressive regimens may subsequently lessen its impact. This pilot study assesses the potential applicability of perioperative non-invasive cardiac output monitoring (NICOM), transit-time flow monitoring (TTFM) of the transplant renal artery and pre-/perioperative thromboelastography (TEG) in the early prediction of DGF and perioperative complications.
  
  
  METHODS
  Ten consecutive living-related renal allograft recipients were studied. Non-invasive cardiac output monitoring commenced immediately following induction of anaesthesia and was maintained throughout the perioperative period. Doppler-based TTFM was performed during natural haemostatic pauses in the transplant surgery: immediately following graft reperfusion and following ureteric implantation. Central venous blood sampling for TEG was performed following induction of anaesthesia and during abdominal closure.
  
  
  RESULTS
  A single incidence of DGF was seen within the studied cohort and one intra-operative (thrombotic) complication noted. NICOM confirmed a predictable trend of increased cardiac index (CI) following allograft reperfusion (mean CI - clamped: 3.17 ± 0.29 L/min/m(2), post-reperfusion: 3.50 ± 0.35 L/min/m(2); P < 0.05) mediated by a significant reduction in total peripheral resistance. Reduced TTFM at the point of allograft reperfusion (227 ml/min c.f. mean; 411 ml/min (95% CI: 358 to 465)) was identified in a subject who experienced intra-operative transplant renal artery thrombosis. TEG data exhibited significant reductions in clot lysis (LY30 (%): pre-op: 1.0 (0.29 to 1.71), post reperfusion 0.33 (0.15 to 0.80); P = 0.02) and a trend towards increased clot initiation following allograft reperfusion.
  
  
  CONCLUSIONS
  Reduced renal arterial blood flow (falling without the 95% CI of the mean), was able to accurately predict anastomotic complications within this pilot study. TEG data suggest the emergence of a prothrombotic state, of uncertain clinical significance, following allograft reperfusion. Abrogation of characteristic haemodynamic trends, as determined by NICOM, following allograft reperfusion may permit prediction of individuals at risk of DGF. The findings of this pilot study mandate a larger definitive trial to determine the clinical applications and predictive value of these technologies.
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry CV2 2DX, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Goodyear
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry CV2 2DX, UK.
authors.forename: James
authors.initials: J
authors.lastname: Barnes
authors.affiliation: University of Sheffield Medical School, Beech Hill Rd, Sheffield, South Yorkshire S10 2RX, UK.
authors.forename: Caitlin E
authors.initials: CE
authors.lastname: Imray
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry CV2 2DX, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Higgins
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry CV2 2DX, UK.
authors.forename: For T
authors.initials: FT
authors.lastname: Lam
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry CV2 2DX, UK.
authors.forename: S Habib
authors.initials: SH
authors.lastname: Kashi
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry CV2 2DX, UK.
authors.forename: Lam C
authors.initials: LC
authors.lastname: Tan
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry CV2 2DX, UK ; Warwick Medical School, University of Warwick, Gibbet Hill Rd, Coventry CV4 7AL, UK.
authors.forename: Christopher He
authors.initials: CH
authors.lastname: Imray
keywords: DGF; Delayed graft function; Living-related; NICOM; Non-invasive cardiac output monitoring; Renal transplant; TEG; TTFM; Thromboelastography; Thrombosis; Transit time flow monitoring