Intraoperative fluid administration volumes during pediatric liver transplantation and postoperative outcomes: A multicenter analysis

INTRODUCTION

Fluid administration is an important aspect of the management of children undergoing liver transplantation and may impact postoperative outcomes. Our aim was to evaluate the association between volume of intraoperative fluid administration and our primary outcome, the duration of postoperative mechanical ventilation following pediatric liver transplantation. Secondary outcomes included intensive care unit length of stay and hospital length of stay.

METHODS

We conducted a multicenter, retrospective cohort study using electronic data from three major pediatric liver transplant centers. Intraoperative fluid administration was indexed to weight and duration of anesthesia. Univariate and stepwise linear regression analyses were conducted.

RESULTS

Among 286 successful pediatric liver transplants, the median duration of postoperative mechanical ventilation was 10.8 h (IQR 0.0, 35.4), the median intensive care unit length of stay was 4.3 days (IQR 2.7, 6.8), and the median hospital length of stay was 13.6 days (9.8, 21.1). Univariate linear regression showed a weak correlation between intraoperative fluids and duration of ventilation (r2  = .037, p = .001). Following stepwise linear regression, intraoperative fluid administration remained weakly correlated (r2  = .161, p = .04) with duration of postoperative ventilation. The following variables were also independently correlated with duration of ventilation: center (Riley Children's Health versus Children's Health Dallas, p = .001), and open abdominal incision after transplant (p = .001).

DISCUSSION

The amount of intraoperative fluid administration is correlated with duration of postoperative mechanical ventilation in children undergoing liver transplantation, however, it does not seem to be a strong factor.

CONCLUSIONS

Other modifiable factors should be sought which may lead to improved postoperative outcomes in this highly vulnerable patient population.

Local Anesthetic Injection Before Incision Decreases General Anesthesia Requirements in Pediatric Trigger Thumb Release: A Randomized Controlled Trial

BACKGROUND

Animal studies have shown evidence of neurotoxicity from inhalational anesthesia, yet clinical studies have been less conclusive. While ongoing studies investigate the clinical significance of anesthesia-associated neurodevelopmental changes in young children, reducing anesthetic exposure in pediatric orthopaedic surgery is prudent. The primary objective of this study is to determine if local anesthetic injection before surgical incision versus after surgical release decreased inhalational anesthetic exposure in children undergoing unilateral trigger thumb release. The secondary objectives were to determine if the timing of local anesthetic injection affected postoperative pain or length of stay.

METHODS

This was a single-center randomized controlled trial of pediatric patients (4 y and below) undergoing unilateral trigger thumb release. Subjects were randomized into preincision or postrelease local anesthesia injection groups. The surgeon was aware of the treatment group, while the anesthesiologist was blinded. Patient demographics, operative times, cumulative sevoflurane dose, and postoperative anesthesia care unit recovery characteristics were collected. The χ2, Fisher exact, and Mann-Whitney U tests were conducted.

RESULTS

A total of 24 subjects were enrolled, with 13 randomized to the preincision injection group and 11 to the postprocedure injection group. There was no significant difference in age, sex, operative time, or tourniquet time between groups. There was a significant difference in the cumulative sevoflurane dose between the preincision injection group (23.2 vol%; interquartile range: 21.7 to 27.6) and the postprocedure injection group (28.1 vol%; interquartile range: 27 to 30) (P=0.03), with a 21% reduction in cumulative dose. There were no significant differences in postoperative pain scores, use of rescue pain medications, the incidence of nausea, or time to discharge between groups.

CONCLUSIONS

Administering local anesthesia before incision versus at the end of the procedure significantly decreased cumulative sevoflurane dose for unilateral trigger thumb release. The results of this study suggest that local anesthetic injection before the incision is a low risk, easy method to reduce general anesthesia requirements during trigger thumb release and could decrease sevoflurane exposure more substantially in longer procedures and mitigate risks of neurotoxicity. Preincision injection with local anesthetic should be incorporated into routine clinical practice.

LEVEL OF EVIDENCE

Level I.

When does apparatus dead space matter for the pediatric patient?

Physiologic dead space is defined as the volume of the lung where gas exchange does not occur. Apparatus dead space increases dead space volume, causing either increased PaCO2 or the need to increase minute ventilation to maintain normocapnia. Children are especially vulnerable because small increases in apparatus dead space can significantly increase dead space to tidal volume ratio (Vd/Vt). The effect of changes in dead space on arterial CO2 (PaCO2) and required minute ventilation were calculated for patients weighing 2 to 17 kg that corresponds to 0 to 36 months of age. Apparatus volumes for typical devices were obtained from the manufacturer or measured by the volume of water required to fill the device. The relationship between the fraction of alveolar CO2 (FaCO2) and dead space volume (Vd) was derived from the Bohr equation, FaCO2 = VCO2/(RR*(Vt - Vd)), where VCO2 is CO2 production, RR is respiratory rate, and Vt is tidal volume. VCO2 was estimated by using Brody's equation for humans aged up to 36 months, (VCO2 = 5.56*(wt)), where weight is in kilogram. Initial conditions were Vt = 8 mL/kg, Vd/Vt = 0.3, and a RR of 20 breaths per minute. The relationship between PaCO2 and dead space was determined for increasing Vd. Rearranging the Bohr equation, the RR required to maintain PaCO2 of 40 mm·Hg was determined as dead space increased. The apparatus Vd of typical device arrangements ranged from 8 to 55 mL, and these values were used for the dead space values in the model. PaCO2 increased exponentially with increasing apparatus dead space. For smaller patients, the PaCO2 increased more rapidly for small changes in Vd than that in larger patients. Similarly, RR required to maintain PaCO2 of 40 mm·Hg increased exponentially with increasing dead space. Increasing apparatus Vd can lead to exponential increases in PaCO2 and/or RR required to maintain normal PaCO2. The effect on PaCO2 is less as patient weight increases, but these data suggest it can be significant for typical circuit components up to at least 17 kg or aged 36 months.