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Evaluating T-wave amplitude as a guide for detecting intravascular injection of a test dose in anesthetized children
1Department of Anesthesia, Akita University School of Medicine, Japan. mtanaka@med.akita-u.ac.jp
Insights
Changes in T-wave amplitude are as effective as heart rate increases for detecting accidental intravascular injection of epinephrine test doses in anesthetized children. This finding offers a reliable method for patient safety during anesthesia.
Area of Science:
- Anesthesiology
- Pediatric Anesthesia
- Cardiovascular Monitoring
Background:
- Accidental intravascular injection of local anesthetics can lead to severe complications.
- Epinephrine-containing test doses are used to detect such injections.
- Previous reports suggest T-wave amplitude changes may indicate intravascular injection.
Purpose of the Study:
- To prospectively evaluate T-wave amplitude changes as a reliable indicator of intravascular injection.
- To compare the effectiveness of T-wave amplitude changes with heart rate changes in detecting intravascular injection.
- To assess the diagnostic accuracy of T-wave amplitude for intravascular injection in pediatric patients.
Main Methods:
- Prospective study of 32 ASA physical status I pediatric patients undergoing elective surgery.
- Patients received sevoflurane anesthesia with nitrous oxide.
- Random assignment to saline or an epinephrine-containing lidocaine test dose.
- Continuous electrocardiography (lead II) and intermittent heart rate and blood pressure monitoring.
Main Results:
- All 16 patients receiving the epinephrine test dose showed significant T-wave amplitude increases (> or = 25%).
- Heart rate and systolic blood pressure also increased significantly in the test dose group.
- No patients receiving saline showed significant changes in T-wave amplitude, heart rate, or blood pressure.
- Sensitivity, specificity, and predictive values were 100% for both T-wave amplitude and heart rate criteria.
Conclusions:
- T-wave amplitude increases of > or = 25% are a highly sensitive and specific indicator of intravascular injection.
- T-wave amplitude changes are as effective as heart rate increases for detecting intravascular injection in sevoflurane-anesthetized children.
- This finding provides a valuable, non-invasive monitoring tool for patient safety during pediatric anesthesia.
Unlabelled:
Previous reports have suggested that accidental intravascular injection of an epinephrine-containing test dose increases T-wave amplitude in anesthetized children. We designed this study to prospectively determine whether changes in T-wave amplitude could be a reliable indicator for detecting intravascular injection. We studied 32 ASA physical status I infants and children (3.4 +/- 1.7 yr) undergoing elective minor surgeries during 1.0 minimum alveolar anesthetic concentration of sevoflurane and 67% nitrous oxide in oxygen. After the i.v. administration of atropine 0.01 mg/kg, the patients were randomly assigned to receive either saline (n = 16) or a test dose consisting of 1% lidocaine (0.1 mL/kg) with 1:200,000 epinephrine (0.5 microg/kg, n = 16) via a peripheral vein to simulate the intravascular injection of the test dose. Heart rate (HR) and systolic blood pressure (SBP) were recorded every 20 and 30 s, respectively, and the T-wave amplitude of lead II was continuously recorded for subsequent analysis. Of the 16 children receiving the test dose, 16, 13, and 16 developed increases in HR, SBP, and T-wave amplitude > or = 10 bpm, > or = 15 mm Hg, and > or = 25%, occurring at 30 +/- 7, 70 +/- 31, and 20 +/- 5 s, respectively. Because no patient receiving saline met these criteria, sensitivity, specificity, and positive and negative predictive values were all 100% based on the criteria using the T-wave amplitude and the peak HR. Our results suggest that changes in T-wave amplitude are as effective as HR for detecting the intravascular injection of an epinephrine-containing test dose in sevoflurane-anesthetized children.
Implications:
To determine whether an epidurally administered local anesthetic is unintentionally injected into a blood vessel, a small dose of epinephrine is often added to a local anesthetic. We found that increases in T-wave amplitude by > or = 25% in lead II monitor electrocardiography are as effective as a heart rate increase > or = 10 bpm for detecting intravascular injection in sevoflurane-anesthetized children.