Positive fluid balances during the perioperative period of obstetric patients and their adverse effects.
Asariel Rodríguez-Inzunza1, Leslian Mejía-Gómez2, Ivan Maldonado-Cruz1, Rosalinda Sánchez-Peña1, Orlando Carrillo-Torres2.

1. Obstetric Intensive Care Unit, Women's hospital “Dr. Rafael P. Gamboa”, Tuxtla Gutiérrez, Chiapas, 
2. Intensive Care Unit, General Hospital of Mexico “Dr. Eduardo Liceaga”, Mexico City, México

Corresponding author email: dr.asariel@hotmail.com
Introduction: Current concepts in fluid resuscitation in obstetric patients, based on the subgroup with obstetric hemorrhage, focus on individualization and minimizing risks of fluid overload. The type of solutions used, the global volume administered, is associated with fluid overload and organ dysfunction, increasing the days of hospital stay, morbidity and mortality [1].
Currently, the type of fluid used for fluid resuscitation is based in many cases on the preferences of the physician who indicates it and not on the evidence from high quality clinical studies.
The cornerstone of treatment for hypovolemic shock in obstetric hemorrhage is the initiation of intravenous fluid therapy, where goal-directed resuscitation should be considered. In cases of obstetric hemorrhage, a lower preload will be considered, the replacement of extracellular losses with isotonic crystalloids in a timely manner and based on protocols compared with colloids (such as human albumin), as this causes less tissue edema [2]. The care of the critically ill pregnant patient depends on the compromised organs that require support, per administered dose of a solution, the toxicity is dependent on the type and composition of the administered fluid, on the pathophysiology of the disease and on the susceptibility of the patient. After preload stabilization, hypervolemia with crystalloids, colloids or blood products should be avoided as much as possible, due to the risk of exceeding the volume into the interstitial space by exceeding cardiac preload. Goal-directed therapy is recommended with the goal of maintaining adequate tissue perfusion that has a direct effect on mortality [3].
The conceptual model of Malbrain et al. proposes to treat fluid therapy like any drug, considering pharmacokinetics, pharmacodynamics and toxicity, in order to reduce the risk of complications. An epidemiological model of fluid balance in the critically ill patient with acute kidney injury can span the entire spectrum of the critical obstetric patient. A meta-analysis by Malbrain, et al. shows us that restrictive fluid therapy, regardless of the type of solution used, has a beneficial effect on mortality, the days of stay in intensive care and the risk for abdominal hypertension [4].
Lactate clearance to guide intravenous fluid therapy in shock states, as well as the normalization of this parameter, could be used as a marker to stop intravenous fluid therapy. Static parameters such as increased filling pressures could also mark a target to stop ongoing resuscitation. Dynamic fubctional parameters or a significant increase in stroke volume after the passive leg raising test or a fluid challenge test are sensitive and specific indicators for discontinuing the administration of fluids [5].
Signs of fluid overload, such as peripheral edema and pulmonary edema on chest X-ray are obvious but late markers of the complications caused by fluid overload. However, they can also indicate a poor distribution of fluids in the absence of frank fluid overload, so they cannot be used faithfully in the perioperative period and not in obstetric patients who have physiological changes that alter these conditions. Whenever possible the measurement of extravascular lung water is a better marker [6].

Objectives: The primary objective of the study is to evaluate the relationship between the cumulative fluid balance during the perioperative period and mortality and days of hospital stay. As a secondary objective we evaluate if the fluid balance is associated with new organ dysfunction or worsening by 2 points on the SOFA scale.

Methods: We evaluated retrospectively the records of 34 pregnant patients during the period from January to September 2020 that were admitted to the obstetrical intensive care unit after being operated for the resolution of pregnancy. The main indication for caesarean and intensive care unit admission were: hypertensive disease of pregnancy (66%), followed by obstetric hemorrhage (30%) or other reasons (4%). The amount of fluids administered (in milliters), daily and cumulative fluid balance and type of solutions were recorded during the perioperative period. Also, the days of hospital stay, adverse events including death, admission SOFA, maximum SOFA during the stay and discharge SOFA were recorded.
Design: Retrospective, observational, longitudinal study. Information is collected from the records of patients admitted to the UCIO with calculation of fluid balances at the end of the surgery to determine if there is an association with mortality, days of hospital stay or deterioration in organ function (determined by a change of 2 points in the SOFA score). The SPSS program was used to determine the difference between the independent means by means of Student’s t-test. The grouping variable used was the total fluid balance (positive or negative) upon admission to the ICU and the dependent variables were days of hospital stay and organ failure (defined as a 2-point increase in the SOFA score). It was not possible to analyse mortality predictors since only one patient died in the group of patients with a positive fluid balance and none in the group with a negative fluid balance.
Results: There was no statistically significant difference between the days of hospital stay in patients with a positive vs negative fluid balance. Regarding organ dysfunction, we performed Levene’s test, which was negative for homogeneity (p= 0.01). Albeit not statistically different we did find a difference between patients with positive and negative balances with a p= 0.29 (Table 1).
Discussion: Our work has an evident lack of bibliographic support as there is very little published regarding pregnancy and complications related to positive fluid balance. There is practically no literature available regarding perioperative fluid balance and outcome in this group of patients.  Our results showed no statistically significant differences between patients with positive and negative fluid balance with respect to organ failure and hospital stay. More data need to be collected in similar patients in the future.
References
1.	Natarajan V, Hariharan V, Garg R. Perioperative fluid management in obstetric patients. Anesthesiol Open J. 2018; SE(1): S1-S7. 
2.	Gillissen, Van den Akker, Caram-Deelder D, TeMpOH.study group et al. Association between fluid management and dilutional coagulopathy in severe postpartum haemorrhage: a nationwide retrospective cohort study. BMC Pregnancy and Childbirth (2018).18:398
3.	Taylor CB, Hammond NE, Laba TL, et al Fluid Trips DCE. Drivers of choice of resuscitation fluid in the intensive care unit: a discrete choice experiment. Crit Care Resusc. 2017;19(2):134–41.
4.	Malbrain, M.L.N.G., Van Regenmortel, N., Saugel, B. et al. Principles of fluid management and stewardship in septic shock: it is time to consider the four D’s and the four phases of fluid therapy. Ann. Intensive Care 8, 66 (2018). 
5.	Malbrain MLNG, Marik PE, Witters I, Cordemans C, Kirkpatrick AW, Roberts DJ, et al. Fluid overload, de-resuscitation, and outcomes in critically ill or injured patients: a systematic review with suggestions for clinical practice. Anaesthesiol Intensive Ther. 2014;46:361-80.
6.	Bennett VA, Cecconi M. Perioperative fluid management: From physiology to improving clinical outcomes. Indian J Anaesth. 2017;61: 614-621. 

Positive fluid balances during the perioperative period of obstetric patients and their adverse effects.

2020 has been a challenging year for all. The COVID19 pandemic has provoked profound and probably long-lasting changes to healthcare systems but also the delivery of educational material to colleagues. 


Face-to-face conferences have had to be rescheduled and replaced with online meetings, given the continually evolving travel restrictions. 


The IFAD conference has not been spared these tribulations and we have decided to cancel the physical meeting to replace it by a virtual online meeting.


The 1st Virtual IFAD International Fluid Academy Days will again be a 3 day concise meeting on all aspects of fluid management and hemodynamic monitoring in the critically ill.