The efficacy of plethysmographic pulse wave amplitude as an indicator for intravascular injection of epinephrine-containing epidural test dose in anesthetized adults

In this study, I evaluated the efficacy of plethysmographic pulse wave amplitude (PPWA) in detecting intravascular injection of a simulated epidural test dose containing 15 microg of epinephrine in adults during either sevoflurane or isoflurane inhaled anesthesia and compared its reliability to the classical heart rate (HR; positive if > or =10 bpm) and systolic blood pressure (SBP; positive if > or =15 mm Hg) criteria. Eighty patients were randomized to receive either 1 mean alveolar anesthetic concentration of sevoflurane or 1 mean alveolar anesthetic concentration of isoflurane (n = 40 for each anesthesia group). Patients in each anesthesia group microg of epinephrine IV or 3 mL of saline IV (n = 20 each). HR, SBP, and PPWA were monitored for 5 min after injection. Injection of the test dose resulted in peak PPWA decrease by 61% +/- 17% and 58% +/- 15% at 61 +/- 12 s and 63 +/- 13 s in the sevoflurane and isoflurane groups, respectively. Positive PPWA criterion, as determined from peak increases during saline administration, was a decrease in PPWA > or =10%. Using this value, the sensitivity, specificity, positive predictive, and negative predictive values of PPWA were 100% in both anesthetic groups. On the contrary, sensitivities of 85% and 95% were obtained based on HR criterion in the sevoflurane and isoflurane patients, respectively, and a sensitivity of 90% was obtained in both anesthesia groups on the basis of SBP criterion. In conclusion, PPWA is a reliable alternative to conventional hemodynamic criteria for detection of an intravascular injection of epidural test dose.     

Reduced efficacy of simulated epidural test doses in sevoflurane-anesthetized adults

Purpose

To determine the hemodynamic responses to, and the efficacy of epinephrine-containing epidural test doses, during sevoflurane anesthesia, based on the conventional heart rate (HR) increase ≥20 beats·min^?1, the modified HR increase if ≥ 10 beats·min^?1, and the systolic blood pressure (SBP) increase 15 mmHg criteria.

Methods

One hundred and twenty patients were randomised to receive sevoflurane 0.5, 1 or 2% end-tidal (n = 40 each) and nitrous oxide 67% in oxygen aftertracheal intubation. Each group of patients was further divided into groups receiving 3 ml lidocaine 1.5% plus 15 μg epinephrine (1:200,000) iv, or 3 ml normal saline (n = 20 each). The HR and SBP were monitored for four minutes after injection of the study drug.

Results

Intravenous injection of the test dose produced HR increases ≥20 beats·min^?1 in 18 (90%), 16 (80%) and 14 (70%) patients at sevoflurane concentrations at 0.5, 1 and 2%, respectively, while those receiving saline developed no HR changes. Based on the modified HR criterion, sensitivity, specificity, and positive and negative predictive values were all 100% under sevoflurane concentrations of 0.5 and 1%, but not 2%. On the other hand, all patients in the test dose groups and none in the saline groups developed SBP ≥ 15 mmHg, ensuring 100% efficacy based on the conventional SBP criterion under all sevoflurane concentrations studied. In all patients receiving the intravenous test dose, peak HR occurred 30–45 sec earlier than that of SBP.

Conclusion

During stable sevoflurane anesthesia, peak HR increase ≥ 10 beats·min^?1 should be regarded as a positive response with end-tidal sevoflurane concentration ≤ 1%, and peak SBP increase ≥ 15 mmHg is applicable at sevoflurane concentrations between 0.5 and 2%.     

末梢灌注指数判断儿童氯胺酮基础麻醉下硬膜外试验剂量注入血管的有效性研究

目的 末梢灌注指数(perfusion index,PI)是一种无创监测末梢组织灌注的指标,文章研究在儿童氯胺酮基础麻醉中,PI变化能否作为判断硬膜外利多卡因试验剂量(内含肾上腺素5 mg/L)注入血管的有效指标.方法 40例美国麻醉医师协会(ASA)Ⅰ级,2岁-8岁行下腹、下肢或会阴部择期手术的患儿,采用完全随机分组法分为对照组、试验组两组,每组20例,静脉注入咪达唑仑0.05 mg/kg和2 mg/kg氯胺酮作为基础麻醉,15 min后对照组静注0.1 ml/kg生理盐水,试验组静注0.1 ml/kg 1％利多卡因(内含肾上腺素5 mg/L),最大剂量为3 mL,注药速度为0.4 ml/s,模拟硬膜外利多卡因试验剂量(内含肾上腺素5 mg/L)注入血管.分别记录注药前即刻和注药后3 min内的心率(heart rate,HR)、收缩压(systolic blood pressure,SBP)、T波振幅(Twave amplitude,TWA)和PI. 结果 对照组静注生理盐水后各项监测指标无统计学差异.试验组注射利多卡因(内含肾上腺素5 mg/L)后TWA、SBP、HR和PI较注药前显著变化.其中TWA和HR最大增幅出现在给药后20s.TWA较注药前增加了(23.05±11.74)％,HR增加了(35±6)次/min.注药后PI值明显下降,40 s时最大降幅为(61.4±11.6)％.SBP最大增幅出现在注药后60 s,较注药前增加了(19±10) mm Hg(1 mm Hg=0.133 kPa).PI下降30％作为判断试验剂量误入血管的阳性指标,其敏感度、特异度、阳性和阴性预测值均为100％.结论 儿童氯胺酮基础麻醉下,PI是一种早期判断硬膜外试验剂量注入血管的有效监测指标,PI联合HR、SBP或TWA指标可以有效地监测硬膜外试验剂量注入血管.     

Efficacy of simulated epinephrine-containing epidural test dose after intravenous atropine during isoflurane anesthesia in children

BACKGROUND AND OBJECTIVES: A double-blind, randomized study was performed to investigate heart rate (HR) and blood pressure responses to 2 doses of intravenous (IV) epinephrine (0.5 and 0.75 microg/kg) in 61 children, ages 3 months to 12 years. METHODS: Anesthesia was maintained with isoflurane (age-adjusted 1 minimal alveolar concentration [MAC]) in oxygen. All patients received IV atropine (10 microg/kg) and 5 minutes later were randomized to receive IV solutions (0.1 mL/kg) containing 1% lidocaine (n = 19, group I) with saline; lidocaine 1% with epinephrine 0.5 microg/kg (n = 21, group II); or lidocaine 1% with epinephrine 0.75 microg/kg (n = 21, group III). HR was recorded at 0, 15, 30, 45, 60, 90 seconds, and 2, 3, 4, and 5 minutes after test-dose injection. Systolic blood pressure (SBP), diastolic blood pressure, and end-tidal carbon dioxide were recorded at steady-state isoflurane anesthesia, after the injection of atropine, and at 45-second intervals after test-dose injections. RESULTS: Median maximum increases in HR were similar in groups II and III at 19 and 22 beats per minute (beats/min), respectively. An HR increase of > or =10 beats/min was observed in 19 of 21 patients who received 0.5 microg/kg epinephrine and 21 of 21 patients receiving 0.75 microg/kg. None of the patients in group I developed HR increases > or =10 beats/min. SBP increased > or =15 mm Hg in 17 of 21 patients in group II and 19 of 21 in group III. No dysrhythmias or T-wave amplitude change was noted. CONCLUSIONS: A simulated epidural test dose containing lidocaine 1 mg/kg with epinephrine 0.75 microg/kg, administered IV following atropine, may reliably increase HR to indicate unintentional injection into epidural vessels of children anesthetized with 1 MAC isoflurane.     

Oral clonidine premedication does not change efficacy of simulated epidural test dose in sevoflurane-anesthetized children

BACKGROUND: Caudal epidural anesthesia is often used as an adjunct to general anesthesia and for postoperative pain relief in children. In anesthetized children, epinephrine and isoproterenol are reliable indicators to detect accidental intravascular injection of a test dose. Oral clonidine, a useful premedicant in pediatric anesthesia, modifies hemodynamic responses to sympathomimetics, including catecholamines. The aim of the current study was to determine whether oral clonidine premedication alters the efficacy of a simulated intravascular test dose containing epinephrine or isoproterenol in sevoflurane-anesthetized children. METHODS: One hundred twenty children (aged 1-7 yr) were randomly divided into six groups; control-saline, control-epinephrine, control-isoproterenol, clonidine-saline, clonidine-epinephrine, and clonidine-isoproterenol. The three clonidine groups received oral clonidine 4 microg/kg [corrected] as premedication, whereas the three control groups did not receive any premedication. Anesthesia was maintained with sevoflurane at a level of 1.2 minimum alveolar concentration. After hemodynamics were stable, 0.1 ml/kg of 1% lidocaine containing epinephrine 0.5 mg/kg or isoproterenol 75 ng/kg was intravenously given to the two epinephrine or isoproterenol groups, respectively, to simulate intravascular injection of a test dose. The saline groups received saline alone instead of the test dose. Heart rate, blood pressure, and T-wave amplitude of electrocardiogram were recorded before and after administration of study drugs for subsequent analysis. RESULTS: Test solution containing epinephrine increased heart rate, systolic blood pressure, and T-wave amplitude. Oral clonidine had no effect on elevation of these variables in response to epinephrine. The isoproterenol-containing test dose produced a prominent increase in heart rate and a less pronounced increase in systolic blood pressure and T-wave amplitude. Oral clonidine also failed to modify isoproterenol-induced hemodynamic and T-wave changes. Calculated sensitivity and specificity of epinephrine or isoproterenol were all 100% based on a new heart rate criterion (positive if >/= 10 beats/min) and were unaltered by oral clonidine premedication. CONCLUSIONS: Epinephrine or isoproterenol is a reliable marker to detect accidental intravascular injection of a test dose with 100% sensitivity and specificity based on a new heart rate criterion in sevoflurane-anesthetized children. These data suggest that oral clonidine premedication does not alter the efficacy of a simulated epidural test dose containing epinephrine or isoproterenol.     

The efficacy of a simulated intravascular test dose in sevoflurane-anesthetized children: a dose-response study.

A recent study demonstrated that changes in both heart rate (HR; positive if > or = 10bpm increase) and T-wave amplitude (positive if > or = 25% increase) reliably detect accidental intravascular injection when a full test dose containing epinephrine 0.5 microg/kg is injected intravascularly. We designed this study to prospectively determine whether a smaller dose of epinephrine would produce reliable HR and T-wave changes in sevoflurane-anesthetized children. We studied 80 ASA physical status I infants and children (6-72 mo) undergoing elective surgeries during 1.0 minimum alveolar anesthetic concentration sevoflurane and 67% nitrous oxide in oxygen. After the administration of i.v. atropine 0.01 mg/kg, the patients were randomly assigned to receive either i.v. saline (n = 20), an i.v. test dose (0.1 mL/kg) consisting of 1% lidocaine with 1:200,000 epinephrine (epinephrine 0.5 microg/kg group, n = 20), an i.v. test dose (0.05 mL/kg) (epinephrine 0.25 microg/kg group, n = 20), or an i.v. test dose (0.025 mL/kg) (epinephrine 0.125 microg/kg group, n = 20) via a peripheral vein to simulate the intravascular injection of the test dose. HR and systolic blood pressure were recorded every 20 and 30 s, respectively, and T-wave amplitude of lead II was continuously recorded for subsequent analysis. After the i.v. injection of the test dose, all children in the epinephrine 0.5 and 0.25 microg/kg groups developed positive responses based on the peak T-wave amplitude, whereas all children in the epinephrine 0.5 microg/kg group and 17 children (85%) in the epinephrine 0.25 microg/kg group elicited a positive response according to the peak HR criterion. No false-positive responses were observed with saline injections. Children in the epinephrine 0.125 microg/kg group showed clinically unacceptable efficacy based on either criterion. We conclude that the efficacies of detecting an intravascular injection of the test dose based on the hemodynamic and T-wave criteria are reduced with smaller doses of epinephrine and that HR and T-wave changes are still useful indicators in most patients if epinephrine 0.25 microg/kg is accidentally injected intravascularly. IMPLICATIONS: To determine whether an epidurally administered local anesthetic has been unintentionally injected into a blood vessel, a small dose of epinephrine is often added to a local anesthetic. We found that an increase in T-wave amplitude > or = 25% in lead II and a heart rate increase > or = 10 bpm are useful indicators for detecting the accidental intravascular injection of a small dose of epinephrine in sevoflurane-anesthetized children.     

A comparative study of hemodynamic and T-wave criteria for detecting intravascular injection of the test dose (epinephrine) in sevoflurane-anesthetized adults.

This study was designed to determine the efficacy of heart rate (HR), systolic blood pressure (SBP), and changes in T-wave morphology in detecting intravascular injection of 15 microg of epinephrine (test dose) in sevoflurane-anesthetized adults. In addition, the testing threshold using the T-wave amplitude was derived. Ninety-six healthy patients were randomized to receive end-tidal sevoflurane 0.5%, 1%, or 2% and nitrous oxide 67% in oxygen (n = 32 for each sevoflurane concentration). Each group of patients was further randomized to receive 3 mL of 1.5% lidocaine plus 15 microg of epinephrine IV or 3 mL of saline IV (n = 16 each). HR, SBP, and T-wave amplitude were continuously monitored for 5 min after the IV injection of the study drug. None receiving IV saline and 15,15, and 14 patients receiving the IV test dose developed HR increases > or =10 bpm during 0.5%, 1%, and 2% sevoflurane, respectively. No patient receiving saline and all patients receiving the test dose developed SBP increases > or =15 mm Hg. T-wave amplitude decreased by >0.1 mV and by >25% in all patients receiving the IV test dose, and its magnitude was similar regardless of the sevoflurane concentrations. When 0.1-mV and 25% decreases in T-wave amplitude were considered as testing thresholds, 100% sensitivities and specificities were obtained. We conclude that a peak SBP increase > or =15 mm Hg and a decrease in T-wave amplitude > or =0.1 mV and > or =25% are more reliable than a HR increase > or =10 bpm for detecting intravascular injection of epinephrine-containing test dose during sevoflurane anesthesia. IMPLICATIONS: To determine whether an epidural catheter resides in a blood vessel, a standard test dose containing a local anesthetic and 15 microg of epinephrine is used. We found that, in sevoflurane-anesthetized adult patients, a systolic blood pressure increase > or =15 mm Hg and a decrease in T-wave amplitude > or =0.1 mV and > or =25% in lead II, but not a heart rate increase > or =10 bpm, are reliable indicators for detecting intravascular injection.     

T-wave amplitude as an indicator for detecting intravascular injection of epinephrine test dose in awake and anesthetized elderly patients.

Aging is associated with reduced heart rate (HR) responsiveness to a simulated IV test dose containing epinephrine. We tested the hypothesis that a more contemporary T-wave criterion (positive if there was a > or = 25% decrease in T-wave amplitude) was applicable in both awake and anesthetized older patients. Sixteen healthy patients > or = 65 yr old first received 3 mL of normal saline IV, followed 4 min later by 1.5% lidocaine 3 mL containing 15 microg epinephrine (1:200,000) IV in the supine position when awake, and they were anesthetized with stable 2% end-tidal sevoflurane and 67% nitrous oxide. HR, systolic blood pressure (SBP) determined invasively, and lead II of the electrocardiogram were continuously recorded for 4 min after the IV injections of saline and the test dose. A sensitivity of 88% and a negative predictive value of 89% were obtained in awake patients on the basis of the conventional HR criterion (positive if there was a > or = 20 bpm increase), whereas a sensitivity of 81% and a negative predictive value of 84% were obtained during sevoflurane anesthesia on the basis of the modified HR criterion (positive if there was a > or = 10 bpm increase). However, sensitivities, specificities, and positive and negative predictive values were all 100% on the basis of the SBP (positive if a > or = 15 mm Hg increase was recorded with an arterial line) and the T-wave criteria for both awake and anesthetized conditions. These results suggest that the SBP and T-wave criteria should be applied in awake and anesthetized elderly patients for detecting accidental intravascular injection of the epinephrine-containing test dose. IMPLICATIONS: To determine whether an epidural catheter is in a blood vessel, an epidural test dose containing 15 microg epinephrine is often used. We found that an increase in systolic blood pressure and a decrease in T-wave amplitude, but not an increase in heart rate, seem to be reliable indicators for detecting accidental intravascular injection in both awake and sevoflurane-anesthetized patients > or = 65 yr old.     

Aging reduces the efficacy of the simulated epidural test dose in anesthetized adults

Aging is associated with reduced beta-adrenergic responsiveness. However, the age-related effects on hemodynamic changes and effectiveness of a simulated epidural IV test dose have not been defined during general anesthesia. We studied 20 (140 total) consecutive patients (ASA physical status I) assigned in each of the following age groups after endotracheal intubation and during stable end-tidal sevoflurane 2% and 67% nitrous oxide anesthesia (in yr): 10s, 20s, 30s, 40s, 50s, 60s, and 70s. Each group first received normal saline 3 mL IV, followed 4 min later by 1.5% lidocaine 3 mL plus 15 microg epinephrine (1:200,000) IV for 5 s. Heart rate (HR) and systolic blood pressure (SBP) were continuously monitored for 4 min after saline administration and the test dose injections. None receiving IV saline and all patients receiving IV test dose in age groups 10s to 50s developed HR increases > or = 10 bpm, whereas 17 and 13 patients met this HR criterion in age groups 60s and 70s (85% and 65% sensitivities), respectively. There was a significant inverse correlation between the maximum HR increase and the age (P: < 0.001 by Spearman's rank correlation). However, none receiving saline and all patients receiving IV test dose in all age groups developed SBP increases of 15 mm Hg, resulting in 100% efficacy based on the SBP criterion. We conclude that during stable sevoflurane anesthesia administration (a) the efficacy based on the HR criterion for detecting accidental intravascular injection of the epidural test dose is age-dependent, (b) the HR criterion may be clinically applicable only in patients <60 yr of age, and (c) the SBP criterion is effective for all age groups studied. IMPLICATIONS: To determine whether an epidurally administered local anesthetic has been unintentionally injected into a blood vessel, a small dose of epinephrine is often added to a local anesthetic. We found that an increase in systolic blood pressure > or = 15 mm Hg is a more useful indicator than an increase in heart rate > or = 10 bpm in the patients > or = 60 yr old during stable sevoflurane anesthesia administration.     

The efficacy of simulated intravascular test dose in sedated patients.

Sedation usually decreases the reliability of subjectively detecting an intravascular test dose, but the efficacies of objective hemodynamic and T-wave criteria remain undetermined. Sixty healthy patients were randomly assigned to receive IV midazolam in 1-mg increments until they were lightly sedated, fentanyl 2 microg/kg followed by incremental midazolam until they were similarly sedated, or no sedative (n = 20 each). Then, normal saline 3 mL was administered IV, followed 4 min later by 1.5% lidocaine 3 mL plus epinephrine 15 microg (1:200,000) in all subjects. Heart rate (HR), systolic blood pressure (SBP) measured by a radial arterial catheter, and lead II of the electrocardiogram were continuously recorded for 4 min after the saline and test dose injections. An IV test dose produced significant increases in HR and SBP and decreases in T-wave amplitude in all subjects. However, the mean maximum increase in HR in patients sedated with midazolam plus fentanyl (31 +/- 14 bpm [mean +/- SD]) was significantly less than in those administered midazolam alone or no sedative (42 +/- 12 and 44 +/- 10 bpm, respectively; P < 0.05). A sensitivity of 100% was obtained on the basis of the traditional HR criterion (positive if > or =20 bpm increase) in patients sedated with midazolam or no sedative, but it was 70% in those with midazolam plus fentanyl (P < 0.05 versus the other two groups). Irrespective of the treatment, sensitivities and specificities of 100% were obtained according to the SBP (positive if > or =15 mm Hg increase) and T-wave (positive if > or =25% decrease in amplitude) criteria. An increase in SBP and a decrease in T-wave amplitude are more reliable than an HR response for detecting accidental intravascular injection of the epinephrine-containing test dose in subjects sedated with midazolam and fentanyl. IMPLICATIONS: To determine whether an epidural catheter is in a blood vessel, an epidural test dose containing 15 microg epinephrine is used. We found that an increase in systolic blood pressure and a decrease in T-wave amplitude seem to be more reliable than a heart rate change for detecting inadvertent intravascular injection of an epinephrine-containing test dose in patients sedated with midazolam and fentanyl.     

The efficacy of hemodynamic and T-wave criteria for detecting intravascular injection of epinephrine test dose in propofol-anesthetized adults

A recent study demonstrated 100% effectiveness of hemodynamic criteria during propofol anesthesia, when a full dose of an epinephrine (15 microg)-containing test dose was injected intravascularly. We designed this dose-response study to determine minimal effective epinephrine doses and efficacies of hemodynamic and T-wave criteria for detecting intravascular injection of the epinephrine test dose in propofol-anesthetized adults. Eighty healthy adult patients were randomly assigned to one of four groups according to a simulated IV test dose using propofol (133 microg center dot kg(-1) center dot min(-1)) and nitrous oxide (FIO(2) = 0.33) anesthesia after endotracheal intubation (n = 20 each). The Saline group received 3 mL of normal saline IV; the Epinephrine-15 group received 3 mL of 1.5% lidocaine containing 15 microg epinephrine; and the Epinephrine-10 and -5 groups received 2 and 1 mL of the test dose of the identical components, respectively. Heart rate (HR), systolic blood pressure (SBP), and lead II of the electrocardiogram were recorded continuously for 5 min after the IV injection of the study drug via a peripheral vein. Sensitivities and specificities of 100% were obtained based on the modified HR (positive if greater-than-or-equal to 10 bpm increase) and the T-wave (positive if greater-than-or-equal 25% in amplitude) criteria if greater-than-or-equal 5 microg of epinephrine was injected IV. Based on the SBP criterion (positive if greater-than-or-equal 15 mm Hg increase), however, 100% sensitivity and specificity were associated only with greater-than-or-equal 10 microg of epinephrine doses. These results suggest that the minimal effective epinephrine doses for detecting unintentional intravascular injection are 5 microg based on the HR and T-wave criteria, and 10 microg based on the SBP criterion in adult patients anesthetized with propofol and nitrous oxide. IMPLICATIONS: Accidental migration of an epidural catheter into a blood vessel is often detected by hemodynamic changes after injecting an epidural test dose containing epinephrine. Our results suggest that 5 microg of epinephrine is not adequate to reliably produce hemodynamic and T-wave alterations in adult patients during propofol anesthesia.     

Evaluating T-wave amplitude as a guide for detecting intravascular injection of a test dose in anesthetized children

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.     

The efficacy of bupivacaine 0.75 per cent as an epidural test dose

Two cases are presented in which a test dose of bupivacaine 0.75 per cent was injected before institution of an epidural block, as a safeguard against inadvertent intrathecal injection. In each case there was immediate evidence of motor and sensory blockade, which gave warning that the epidural catheter was positioned in the subarachnoid space. The experience of these two cases indicates that bupivacaine 0.75 per cent would be appropriate for use as a test dose in epidural anaesthesia.