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Preoperative Fluid Fasting Times and Postinduction Low Blood Pressure in Children: A Retrospective Analysis
Allan F Simpao1, Lezhou Wu, Olivia Nelson
1From the Departments of Anesthesiology and Critical Care Medicine (A.F.S., L.W., O.N., J.A.G., J.M.T., J.O.W., W.T.M., F.-C.T., A.J.M., P.A.S.) Biomedical and Health Informatics (A.F.S., L.W., J.A.G., J.M.T., J.O.W., F.-C.T., A.J.M.), Children's Hospital of Philadelphia, Philadelphia, Pennsylvania the Department of Anesthesiology and Critical Care, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (A.F.S., J.A.G., J.M.T., J.O.W., W.T.M., F.-C.T., A.J.M., P.A.S.).
Insights
Prolonged clear fluid fasting in children undergoing anesthesia is linked to a higher risk of low blood pressure during surgical preparation. This association appears nonlinear, with specific fasting durations posing greater risks.
Area of Science:
- Pediatric Anesthesiology
- Critical Care Medicine
- Clinical Research
Background:
- Children require fasting before elective general anesthesia.
- Prolonged fasting may lead to volume depletion and low blood pressure.
- This study investigated the link between fluid fasting duration and postinduction hypotension.
Purpose of the Study:
- To assess the association between fluid fasting duration and postinduction low blood pressure in children.
- To determine if longer fasting periods increase the risk of hypotension.
- To analyze the relationship between fasting duration and blood pressure changes during anesthesia preparation.
Main Methods:
- Retrospective cohort study of 15,543 children undergoing elective surgery.
- Data collected from 2016-2017 at Children's Hospital of Philadelphia.
- Low blood pressure defined as systolic blood pressure <2 SD below age/sex norms; analyzed in two epochs: induction to anesthesia prep (epoch 1) and during surgical prep (epoch 2).
Main Results:
- In epoch 1, 5.2% of children experienced low blood pressure with no association to fasting duration.
- In epoch 2, 6.9% experienced low blood pressure.
- Fasting 4-8 hours (aOR 1.33) and >12 hours (aOR 1.28) were significantly associated with higher odds of low blood pressure compared to <4 hours.
Conclusions:
- Longer clear fluid fasting durations in anesthetized children are associated with an increased risk of postinduction low blood pressure during surgical preparation.
- The association between fasting duration and hypotension risk appears nonlinear.
- Fasting for 4-8 hours or more than 12 hours poses a higher risk for low blood pressure compared to shorter fasting periods.
Background:
Children are required to fast before elective general anesthesia. This study hypothesized that prolonged fasting causes volume depletion that manifests as low blood pressure. This study aimed to assess the association between fluid fasting duration and postinduction low blood pressure.
Methods:
A retrospective cohort study was performed of 15,543 anesthetized children without preinduction venous access who underwent elective surgery from 2016 to 2017 at Children's Hospital of Philadelphia. Low blood pressure was defined as systolic blood pressure lower than 2 standard deviations below the mean (approximately the 2.5th percentile) for sex- and age-specific reference values. Two epochs were assessed: epoch 1 was from induction to completion of anesthesia preparation, and epoch 2 was during surgical preparation.
Results:
In epoch 1, the incidence of low systolic blood pressure was 5.2% (697 of 13,497), and no association was observed with the fluid fasting time groups: less than 4 h (4.6%, 141 of 3,081), 4 to 8 h (6.0%, 219 of 3,652), 8 to 12 h (4.9%, 124 of 2,526), and more than 12 h (5.0%, 213 of 4,238). In epoch 2, the incidence of low systolic blood pressure was 6.9% (889 of 12,917) and varied across the fasting groups: less than 4 h (5.6%, 162 of 2,918), 4 to 8 h (8.1%, 285 of 3,531), 8 to 12 h (5.9%, 143 of 2,423), and more than 12 h (7.4%, 299 of 4,045); after adjusting for confounders, fasting 4 to 8 h (adjusted odds ratio, 1.33; 95% CI, 1.07 to 1.64; P = 0.009) and greater than 12 h (adjusted odds ratio, 1.28; 95% CI, 1.04 to 1.57; P = 0.018) were associated with significantly higher odds of low systolic blood pressure compared with the group who fasted less than 4 h, whereas the increased odds of low systolic blood pressure associated with fasting 8 to 12 h (adjusted odds ratio, 1.11; 95% CI, 0.87 to 1.42; P = 0.391) was nonsignificant.
Conclusions:
Longer durations of clear fluid fasting in anesthetized children were associated with increased risk of postinduction low blood pressure during surgical preparation, although this association appeared nonlinear.
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Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.