The haemodynamic effects of crystalloid and colloid volume resuscitation on primary, derived and efficiency variables in post-CABG patients

Abstract

Background Recent studies in haemodynamic management have focused on fluid management and assessed its effects in terms of increase in cardiac output based on fluid challenges or variations in pulse pressure caused by cyclical positive pressure ventilation. The theoretical scope may be characterised as Starling-oriented. This approach ignores the actual events of right-sided excitation and left-sided response which is consistently described in a Guyton-oriented model of the cardiovascular system. Aim Based on data from a previous study, we aim to elucidate the primary response to crystalloid and colloid fluids in terms of cardiac output, mean blood pressure and right atrial pressure as well as derived and efficiency variables defined in terms of Guyton venous return physiology. Method Re-analyses of previously published data. Results Cardiac output invariably increased on infusion of crystalloid and colloid solutions, whereas static and dynamic efficiency measures declined in spite of increasing pressure gradient for venous return. Discussion We argue that primary as well as derived and efficiency measures should be reported and discussed when haemodynamic studies are reported involving fluid administrations.

Volume status and volume responsiveness in postoperative cardiac surgical patients: An observational, multicentre cohort study

“…The calculated initial stressed volume was quite similar to the 1.7 l reported in a previous study of P ms 20 and corresponds well to a proportion of 30% of the total blood volume demonstrated during no‐flow conditions on cardiopulmonary bypass 21 . The baseline P msa in this study is very similar to the 15‐18 mm Hg found previously in three smaller studies of postoperative cardiac surgery patients using the same mathematical model 11,12,22 . The range of P msa is furthermore similar to the mean systemic filling pressure of 18‐21 mm Hg obtained from successive inspiratory hold manoeuvres in patients following cardiac surgery 20,23 .…”

“…The range of P msa is furthermore similar to the mean systemic filling pressure of 18‐21 mm Hg obtained from successive inspiratory hold manoeuvres in patients following cardiac surgery 20,23 . The increased P msa following boluses is consistent with responses to volume loading reported earlier following cardiac surgery, 11‐13,20,22,23 hepatic surgery 24 as well as in general ICU patients 25 . Taken together, these studies lend credibility to the concept of using P msa to assess volume state and responses to increased intravascular filling.…”

Feasibility to estimate mean systemic filling pressure with inspiratory holds at the bedside

“…Interestingly, 100 ml of colloids did significantly increase MSFP, whereas 100 ml of crystalloids did not. A previous study also found the response on crystalloid variable in post-CABG patients (Sondergaard et al, 2019). Perhaps a capillary leak syndrome with endothelial glycocalyx shedding can partly explain our results, or that the expected transudation of crystalloid into the interstitium occurred rapidly in patients after cardiac surgery (Dekker et al, 2019).…”