Heart Rate Criteria Research Articles

Influência do protocolo ergométrico na ocorrência de diferentes critérios de esforço máximo

INTRODUÇÃO E OBJETIVO: Neste estudo investigamos a influência de diferentes protocolos ergométricos na ocorrência dos critérios de esforço máximo. MÉTODOS: Nove sujeitos fisicamente ativos (23 ± 4 anos, 177 ± 10cm, e 77,1 ± 16kg) realizaram três testes de esforço (PR1 - 15W·min-1, PR2 - 50W·3 min-1, e PR3 - 50W·5 min-1) no cicloergômetro. O consumo de oxigênio foi medido em circuito aberto e integrado a cada 20s. Adotaram-se como critérios de esforço máximo: o platô no consumo de oxigênio < 150 mL·min-1; frequência cardíaca máxima (FCmáx) > 95% prevista pela idade; lactato > 8,0 mM; e RER > 1,1. RESULTADOS: O VO2máx não apresentou diferenças entre os protocolos (2,68 ± 1,0; 2,58 ± 1,0 e 2,99 ± 1,3L·min-1 para PR1, PR2 e PR3, p = 0,72). A maior ocorrência do platô foi observada em PR1 (cinco sujeitos). O critério da frequência cardíaca máxima foi satisfeito em três sujeitos em PR3, e o critério do lactato em seis sujeitos, no mesmo protocolo (PR3). O RER > 1,1 foi observado em seis sujeitos em PR1. CONCLUSÃO: Concluímos que a ocorrência de diferentes critérios de esforço máximo é influenciada pela escolha do protocolo ergométrico, não indicando, contudo, valores distintos de VO2máx

Effect of Acute Posttrauma Propranolol on PTSD Outcome and Physiological Responses During Script‐Driven Imagery

Animal and human research suggests that the development of posttraumatic stress disorder (PTSD) may involve the overconsolidation of memories of a traumatic experience. Previous studies have attempted to use pharmaceutical agents, especially the β-adrenergic blocker propranolol, to reduce this overconsolidation. In this randomized, placebo-controlled study of the efficacy of propranolol in reducing the development of PTSD, we optimized dosages and conducted both psychophysiological and clinical assessments 1 and 3 months after the traumatic event. Forty-one emergency department patients who had experienced a qualifying acute psychological trauma were randomized to receive up to 240 mg/day of propranolol or placebo for 19 days. At 4 and 12 weeks post-trauma, PTSD symptoms were assessed. One week later, participants engaged in script-driven imagery of their traumatic event while psychophysiological responses were measured. Physiological reactivity during script-driven traumatic imagery, severity of PTSD symptoms, and the rate of the PTSD diagnostic outcome were not significantly different between the two groups. However, post hoc subgroup analyses showed that in participants with high drug adherence, at the 5-week posttrauma assessment, physiological reactivity was significantly lower during script-driven imagery in the propranolol than in the placebo subjects. The physiological results provide some limited support for a model of PTSD in which a traumatic conditioned response is reduced by posttrauma propranolol. However, the clinical results from this study do not support the preventive use of propranolol in the acute aftermath of a traumatic event.

Emergency Medical Services Transport Decisions in Posttraumatic Circulatory Arrest: Are National Practices Congruent?

To catalog the 9-1-1 emergency medical services (EMS) transport practices for posttraumatic circulatory arrest patients (PTCAPs) in the majority of the nation's largest municipalities and to compare those practices to guidelines recommended by the National Association of EMS Physicians (NAEMSP) and American College of Surgeons Committee on Trauma (ACSCOT). A survey was conducted in 33 of the nation's largest cities primarily to determine whether or not individual EMS systems transport PTCAPs to hospitals and, if so, whether or not the initial electrocardiographic (ECG) rhythm or mechanism of injury affected those transport decisions. All 33 cities (100%) responded. Seven (21%) indicated that EMS would transport an "asystolic blunt trauma patient" emergently or "leave the transport decision to paramedic judgment" despite NAEMSP-ACSCOT guidelines to terminate resuscitation in such cases. Likewise, 15 (46%) of the 33 EMS agencies would transport "asystolic penetrating trauma patients" emergently. Similarly, 27 (82%) would transport penetrating injury patients and 20 (61%) would transport blunt trauma patients with persistent ECG activity but no palpable pulses. However, only five systems had policies that included a minimum ECG heart rate criterion for transport, and all agencies that monitor ECG (n = 32) would transport PTCAPs found with ventricular fibrillation. Many of the nation's highest volume EMS systems transport certain PTCAPs emergently, contrary to NAEMSP-ACSCOT guidelines to terminate resuscitative efforts in such cases. Reasons for these discrepancies should be evaluated to help better delineate applicable consensus guidelines for large urban EMS agencies.

Orthostatic Heart Rate and Blood Pressure in Adolescents: Reference Ranges

This descriptive population study of 307 public high school students, ages 15 to 17 years, was performed to establish reference ranges for orthostatic changes in heart rate and blood pressure in adolescents, and to identify influential variables. Noninvasive measurements of blood pressure and heart rate were obtained. Reference ranges for orthostatic heart rate change in this population at 2 minutes were -2 to +41 beats per minute and at 5 minutes were -1 to +48 beats per minute. Orthostatic blood pressure changes were within the adult range for 98% of adolescents tested. One-third of participants experienced orthostatic symptoms during testing. In conclusion, this study shows that orthostatic symptoms and large orthostatic heart rate changes occur in adolescents. This suggests that the current orthostatic heart rate criterion aiding the diagnosis of adult orthostatic intolerance syndromes is likely not appropriate for adolescents and should be reevaluated.

Positive Intravascular Test Dose Criteria in Children During Total Intravenous Anesthesia with Propofol and Remifentanil Are Different than During Inhaled Anesthesia

The use of local anesthetic test doses is standard practice when performing regional anesthesia. When an intravascular test dose is administered during inhaled anesthesia, the heart rate does not increase in about 25% of children; altered T-wave amplitude is a better indicator. No studies have examined the criteria for a positive result during total i.v. anesthesia (TIVA) in children. We studied the effect of a simulated positive test dose on heart rate, arterial blood pressure, and T-wave amplitude in 17 ASA physical status I or II children receiving TIVA with propofol and remifentanil. Bupivacaine 0.25% 0.1 mL/kg with epinephrine 1:200,000 was injected i.v., and vital signs and electrocardiogram were continuously monitored. Increases of heart rate and arterial blood pressure >10% and T-wave amplitude >25% of baseline were considered clinically significant changes. All subjects had increased systolic and diastolic blood pressure (30.3% +/- 11.7% and 49.3% +/- 16.7%), which peaked within 120 s. Heart rate increases >10% of baseline occurred in 73% of subjects. T-wave amplitude increased in 33.3%, was unchanged in 25%, and decreased in 41.7% of subjects. A positive test dose during TIVA is best detected by increased arterial blood pressure. Twenty-seven percent of intravascular injections were missed using heart rate criteria. T-wave amplitude is not a reliable indicator of intravascular injection during TIVA. This is in marked distinction to what is seen during inhaled anesthesia.

Fire Fighters Under Report Rpe During Maximal Treadmill Testing

PURPOSE: To determine if fire fighters under report their rating of perceived exertion (RPE) during VO2 max testing. METHODS: Maximal VO2 values were determined for fire fighters (FF) (N=92) using the Bruce protocol as part of their annual health and fitness assessment. Criteria to determine if a maximal test was performed were: heart rate (HR) equal to or greater than 85% of age predicted maximum as monitored by EKG, RPE above 17, and RER values above 1.15. Completion of the test was volitional, but all FF were told that certain criteria needed to be met prior to termination in an effort to validate the test. However, they could stop at any time. HR and RER were monitored every 20 seconds throughout the test with RPE being assessed at minute two of each stage and a final RPE was assessed at the completion of the test. When criteria for HR and RER had been met, FF were told of this fact. RESULTS: Forty-six FF met two criteria (HR and RER) with twenty-two additional FF meeting all 3 criteria for a total of sixty-eight. Of the remaining twenty-four FF, twenty-three met only the HR criteria and one FF didn't meet any of the criteria before terminating the test. Therefore, 67.6% of firefighters meeting physiological determinants of a VO2 max test (HR and RER) under reported their RPE. CONCLUSIONS: When utilizing RPE as a determinant of a valid VO2 max test, caution should be used when subjects have been exposed to dangerous or high stress situations when performing job related duties. While only FF were used, similar results may be seen in police, military personnel or those working in high stress situations.

The Efficacy of Perfusion Index as an Indicator for Intravascular Injection of Epinephrine-Containing Epidural Test Dose in Propofol-Anesthetized Adults

Perfusion index (PI) is a noninvasive numerical value of peripheral perfusion obtained from a pulse oximeter. In this study, we evaluated the efficacy of PI for detecting intravascular injection of a simulated epidural test dose containing 15 mug of epinephrine in adults during propofol-based anesthesia and compared its reliability with the conventional heart rate (HR) (positive if >or=10 bpm) and systolic blood pressure (SBP) (positive if >or=15 mm Hg) criteria. Forty patients scheduled for elective general surgery under total IV anesthesia were randomized to receive either 3 mL of lidocaine 15 mg/mL with epinephrine 5 microg/mL or 3 mL of saline IV (n = 20 each). HR, SBP, and PI were monitored for 5 min after injection. Injecting the test dose resulted in an average maximum PI decrease by 65% +/- 13% at 39 +/- 15 s. Moreover, maximal increases in HR and SBP were 19 +/- 8 bpm at 49 +/- 25 s and 17 +/- 7 mm Hg at 102 +/- 34 s after test dose injections, respectively. Using the PI criterion for intravascular injection (positive if PI decreases >or=10% from the preinjection value) the sensitivity, specificity, positive predictive, and negative predictive values were 100% (95% confidence interval [CI]; CI = 83%-100%). On the contrary, sensitivities of 95% (CI = 76%-99%) and 90% (CI = 70%-97%) were obtained based on HR and SBP criteria, respectively. PI is a reliable alternative to conventional hemodynamic criteria for detection of an intravascular injection of epidural test dose in propofol-anesthetized adult patients.

Plethysmographic Pulse Wave Amplitude Is an Effective Indicator for Intravascular Injection of Epinephrine-Containing Epidural Test Dose in Sevoflurane-Anesthetized Pediatric Patients

Plethysmographic pulse wave amplitude (PPWA) was effective in detecting intravascular injection of epidural test dose with 100% sensitivity and specificity in adults. We evaluated the efficacy of PPWA in detecting intravascular injection of a simulated epidural test dose during sevoflurane anesthesia in pediatric patients. Eighty infants and children were randomized to receive either 0.5 minimal alveolar concentration (MAC) or 1 MAC sevoflurane and nitrous oxide in oxygen. Patients in each anesthesia group were further randomized to receive either 0.1 mL/kg of 1% lidocaine with 1:200,000 epinephrine (0.5 mug/kg of epinephrine) IV to simulate the intravascular injection of epidural test dose or saline. Heart rate (HR), systolic blood pressure (SBP), and PPWA were monitored for 5 min after injection. A positive test response was defined as HR increase > or =10 bpm, SBP increase > or =15 mm Hg, and PPWA decrease > or =10%. Injecting the test dose resulted in an average maximum PPWA decrease by 69% +/- 18% and 58% +/- 14% at 79 +/- 22 and 80 +/- 19 s in the 0.5 MAC and 1 MAC sevoflurane groups, respectively. The sensitivity, specificity, positive predictive, and negative predictive values for PPWA were 100% in both sevoflurane groups, whereas by using HR and SBP criteria, the sensitivity was 90% and 95% respectively during 0.5 MAC sevoflurane anesthesia and 85% for both during 1 MAC sevoflurane anesthesia. PPWA is effective for detection of an intravascular injection of a simulated epidural epinephrine-containing test dose in pediatric patients.

Efficacy of pre-scan beta-blockade and impact of heart rate on image quality in patients undergoing coronary multidetector computed tomography angiography

Objective While beta-blockers are routinely administered to patients prior to coronary computed tomography angiography (CTA), their effectiveness is unknown. We therefore assessed the efficacy of beta-blockade with regards to heart rate (HR) control and image quality in an unselected patient cohort. Methods We studied 150 consecutive patients (104 men/46 female; mean age, 56 ± 13 years) referred for coronary CTA. Intravenous metoprolol (5–20 mg) was administered to patients with a HR >65 beats per minute (bpm). The goal HR was defined as an average HR <65 bpm without a single measurement above 68 bpm. Results Overall, 45% (68/150) of patients met the HR criteria for beta-blocker administration of which 76% (52/68) received metoprolol (mean dose 12 ± 10 mg). Of the 52 patients who received beta-blocker versus the 98 who did not, 18 (35%) versus 62 (64%) patients achieved the goal HR, respectively. All patients who achieved the target HR had an evaluable CTA while five patients who did not achieve the target HR had at least one non-evaluable coronary artery due to motion artifact. There was also a significant reduction in any motion artifact among those who achieved the goal HR as compared to those who did not ( p = 0.001). Logistic regression revealed an increase in the odds of stair step artifact of 11.6% (95% CI: 2.4% decrease, 27.5% increase) per 1 bpm increase in the standard deviation of scan HR. Conclusion Overall, efficacy of beta-blocker administration to reach target HR is limited. Improvements in CT scanner temporal resolution are mandatory to achieve consistently high image quality independent of HR and beta-blocker administration.

Increasing the Use of an Existing Medical Emergency Team in a Teaching Hospital

Cultural barriers in hospital ward staff may limit the use of a Medical Emergency Team (MET) service. In December 2000 the role of the existing Code Blue team in our hospital was expanded to incorporate review of patients fulfilling commonly employed MET criteria. Between January 2001 and June 2003, the average call rate was only 9.8 calls/ 1000 admissions. Anecdotal feedback and a group-administered questionnaire conducted in July 2003 demonstrated a number of obstacles to initiating calls and the system was modified in October 2004. Specifically, emergency response calls were separated into Code Blue calls (for cardiorespiratory arrests) and MET calls (with physiological and worried criteria). Further loud overhead chimes as well as anaesthetist and cardiologist attendance were used only in the case of Code Blue calls (suspected arrests). Finally, the heart rate and respiratory rate criteria for MET service activation were modified. In the 12 months before the intervention (October 2003 to September 2004) there were 817 emergency response calls and 51,963 admissions (15.7 calls/1000 admissions). In the 12 months after the intervention there were 1349 emergency response calls (Code Blue plus MET calls) and 54,593 admissions (24.7 calls/1000 admissions [OR 1.59; 95% CI=1.45-1.73; P<0.0001]). Our findings suggest that increasing the use of an existing service to review patients fulfilling MET criteria requires repeated education and a periodic assessment of site-specific obstacles to utilization.

Maximal Exercise Test Results in Subacute Stroke

Tang A, Sibley KM, Thomas SG, McIlroy WE, Brooks D. Maximal exercise test results in subacute stroke. Objectives To establish the feasibility and reliability of graded maximal exercise testing, suitability of standard indexes of maximum oxygen consumption (V̇ o 2max), and evidence of trial-to-trial practice effects in subacute stroke. Design Descriptive, cross-sectional study. Setting Rehabilitation hospital. Participants Consecutive sample of 35 participants (mean age, 65.7±2.6y; mean days poststroke, 17.6±2.2d). Interventions Not applicable. Main Outcome Measures Graded maximal exercise test using semirecumbent cycle ergometry. A subset (n=20) performed repeated tests to determine test-retest reliability and presence of practice effects. Results Thirty-one (89%) participants completed the exercise test without symptomatic responses (mean peak level of oxygen consumed [V o 2peak], 10.7mL·kg −1·min −1; peak work rate, 39W). Twelve (34%), 15 (44%), and 3 (9%) participants achieved oxygen consumption per unit time (V̇ o 2) plateau, respiratory exchange ratio, and heart rate criteria, respectively. Although test-retest correlations were high (intraclass correlation coefficient range, .67–.87), higher V o 2peak (1.0mL·kg −1·min −1, P=.04) and work rate (7.3W, P=.01) were observed with repeated testing, with no associated increase in reaching standard criteria for V̇ o 2max. Conclusions This work has important implications for developing guidelines for measuring aerobic capacity early after stroke. Although maximal exercise testing using semirecumbent cycle ergometry is feasible, standard V̇ o 2max criteria are not consistently appropriate. At least 1 practice trial is recommended before the actual evaluation is performed.

Effects of Cycled Lighting on Heart Rate in Preterm Infants: Comparing the Use of Standard and Individual Heart Rate Criteria

Effects of Cycled Lighting on Heart Rate in Preterm Infants: Comparing the Use of Standard and Individual Heart Rate Criteria

Effects of Cycled Lighting on Heart Rate in Preterm Infants: Comparing the Use of Standard and Individual Heart Rate Criteria

Effects of Cycled Lighting on Heart Rate in Preterm Infants: Comparing the Use of Standard and Individual Heart Rate Criteria

The Efficacy of Epinephrine-Containing Test Dose during Propofol-Nitrous Oxide Anesthesia with High Dose Fentanyl

Background: The aim of this study is to determine the effect of high dose fentanyl on the test dose containing 15 epinephrine during propofol anesthesia. Methods: One hundred patients with ASA physical status 1 were randomized to receive 2 mg/kg propofol with or without 10/kg fentanyl at the induction of anesthesia (n = 50 each). Anesthesia was maintained with propofol 8 mg/kg/h and 67% nitrous oxide in oxygen. Each group of patients were further divided into a test dose group receiving 1.5% lidocaine 3 ml plus epinephrine 15 or a saline group receiving 3 ml of isotonic saline (n = 25 each). Heart rate (HR) and systolic blood pressure (SBP) were monitored for 4 min after intravenous injection of the study drugs. Results: In the propofol and the propofol-fentanyl group, the intravenous injection of the test dose produced a HR increase 20 bpm (conventional HR criterion) in 25 and 23 out of the total 25 patients, respectively. Therefore, in the propofol-fentanyl group, sensitivity, specificity, positive predictive value, and negative predictive value were 82%, 100%, 100%, and 92.6%. According to the modified HR criterion (HR increase 10 bpm), all the values were 100%. All patients receiving test dose developed SBP increase 15 mmHg. Conclusions: Our results indicate that both HR increase 10 bpm or SBP increase 15 mmHg are clinically applicable during propofol-nitrous oxide anesthesia with 10/kg fentanyl.

Digital Skin Blood Flow as an Indicator for Intravascular Injection of Epinephrine-Containing Simulated Epidural Test Dose in Sevoflurane-Anesthetized Adults

I designed this study to determine the efficacy of heart rate (HR), systolic blood pressure (SBP), and digital skin blood flow (DSBF) in detecting intravascular injection after a simulated epidural test dose containing 15 mug of epinephrine in sevoflurane-anesthetized adults. In addition, the testing threshold using DSBF was derived. Eighty patients were randomized to receive either 0.5 minimum alveolar anesthetic concentration (MAC) sevoflurane or 1.0 MAC sevoflurane and nitrous oxide in oxygen (n = 40 for each sevoflurane concentration). Each group of patients was further randomized to receive either 3 mL of 1.5% lidocaine containing 15 mug of epinephrine IV or 3 mL of saline IV (n = 20 each). HR, SBP, and DSBF were monitored for 5 min after injection. By using the HR (positive if >or=10 bpm increase) and SBP (positive if >or=15 mm Hg increase) criteria, a positive response rate to epinephrine was 95% for both variables during 0.5 MAC and 90% during 1.0 MAC sevoflurane anesthesia. Injection of the test dose resulted in peak DSBF decrease by 87% +/- 8% and 81% +/- 12% at 52 +/- 10 and 53 +/- 13 s in the sevoflurane 0.5 and 1.0 MAC groups, respectively. Positive DSBF criterion, as determined from peak increases during saline administration, was a decrease in DSBF >or=15%. Using this value, the sensitivity, specificity, positive predictive value, and negative predictive value were 100% in both sevoflurane groups. In conclusion, DSBF was superior to conventional hemodynamic criteria for detection of an intravascular injection of epidural test dose. This study examined the efficacy of digital skin blood flow to detect an intravascular injection of an epinephrine-containing epidural test dose. This new variable when measured with a laser Doppler flowmeter was superior to conventional hemodynamic criteria during sevoflurane anesthesia.

Criteria For Maximal Oxygen Uptake In Collegiate Subjects

PURPOSE To measure physiological variables typically recorded at maximal oxygen uptake (VO2max) in college age individuals during a continuous graded exercise test (GXT) on the treadmill (TM) and cycle ergometer (CE). METHODS With a counterbalanced design, 36 female and 15 male college students, aged 18–22 y, completed a TM and CE GXT until volitional exhaustion; GXT were separated by 1 wk. TM GXT velocity was 1 mph faster than the self-selected warm-up pace; grade was increased 2% every 2 min. CE GXT started at 1 kp and 1.5 kp for women and men, respectively; resistance was increased 0.5 kp every 2 min. Heart rate (HR) and rating of perceived exertion (RPE) were measured at the end of each stage. Oxygen consumption (VO2) and respiratory exchange ratio (RER) were averaged and recorded every 30 sec. Blood lactate (BL) was measured 5 min post GXT. Differences between gender and modalities were located with independent and dependent T tests, respectively; α was set at 0.05. RESULTS Current criteria for max are: BL >8.0 mM, HR >age predicted HRmax - 10 bpm, RER >1.15, and a VO2 plateau <2.1 ml.kg- 1·min−1. 85% of subjects reached the BL criterion on either modality; 73% reached the HR criterion on the TM, but only 64% did on the CE; 96% reached the RER criterion on the CE, but only 55% did on the TM; and 54% reached a plateau on the TM, while 24% did on the CE. Approximately 53% achieved at least 3 of the criteria for either test. Significant differences between modalities included RER (0.08 higher on CE) and HR (8.8 bpm higher on TM). Between genders, the only noteworthy difference was HR, which was 6 bpm higher for women on both modalities. CONCLUSIONS These data show the criteria for identifying VO2max should be modality and gender specific. Additionally, the VO2 plateau needs to be reevaluated as a criterion or redefined.

Heat Extraction Through The Palm Of One Hand Improves Aerobic Exercise Endurance And Conditioning In A Hot Environment

Excessive increases in body temperatures can adversely affect physical performance. Tolerable body temperatures are maintained by matching heat production and heat loss. Increases in internal heat production are inherent to physical activity and, unless accompanied by an equivalent increase in heat loss, body temperatures will rise. When it is necessary to perform physical activity in situations where heat dissipation is limited (e.g., while wearing excessive insulation layers or exposure to excessively hot environments), any means of facilitating heat transfer from the body should enhance performance capacity. We had previously developed a methodology for enhancing heat transfer across the skin surface of the hand. The methodology consisted of a chamber that enclosed one hand with the palm of the hand resting on a metal heat exchange surface. A soft seal around the wrist made it possible to draw a slight subatmospheric pressure (about –40mm Hg) in the chamber. Coolant water circulated through the heat exchanger. The concept of the device function is that the subatmospheric pressure increases the filling of the venous plexus underlying the palmar skin and thereby increases the ability to extract heat from that skin surface. PURPOSE to determine to what extent the use of the novel heat transfer methodology could increase aerobic exercise endurance in a hot environment. The efficacy of the device for promoting return of core temperature towards normal following exhaustive exercise in a hot environment was also tested. METHODS Subjects engaged in aerobic exercise in a 40 °C room by walking on a treadmill at 5.63 Km/h. The treadmill slope was elevated to increase work load. The metric for exercise endurance was the time to reach 90% of estimated age-specific maximum heart rate. Initial work loads were adjusted so that subjects would reach the heart rate criterion in 25 to 45 minutes. RESULTS Using the device increased the duration of exercise at this work load by 43%. Using the device without the subatmospheric pressure had no little effect on endurance. In a second study, workload was gradually increased and as work load increased, the device had a decreasing effect on extending endurance time. Recovery, as determined by core temperature parameters, was enhanced with use of the device. CONCLUSIONS Enhancement of heat loss through the heat exchange vascular structures of a single appendage can positively affect both physical performance capacity and post-exertion recovery in situations where natural heat loss is compromised.

Aging Reduces the Efficacy of the Simulated Epidural Test Dose in Anesthetized Adults

Aging is associated with reduced β-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 μg 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 ≥ 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 ≥ 15 mm Hg is a more useful indicator than an increase in heart rate ≥ 10 bpm in the patients ≥ 60 yr old during stable sevoflurane anesthesia administration.

Evaluating Hemodynamic and T Wave Criteria of Simulated Intravascular Test Doses Using Bupivacaine or Isoproterenol in Anesthetized Children

An increase in T wave amplitude ≥25% is a reliable indicator for detecting intravascular injection of lidocaine-epinephrine test dose in anesthetized children. We examined whether a simulated IV test dose containing bupivacaine instead of lidocaine, and isoproterenol instead of epinephrine, produces reliable changes in heart rate (HR) and T wave morphology. One hundred healthy infants and children (6–72 mo) were randomized to one of five groups (n = 20 each) during 1.0 minimum alveolar anesthetic concentration sevoflurane and 67% nitrous oxide in oxygen: atropine pretreatment (0.01 mg/kg IV) followed by 0.25% bupivacaine containing epinephrine 0.5 μg/kg IV, atropine followed by normal saline, atropine followed by 1% lidocaine containing isoproterenol 0.1 μg/kg, saline pretreatment followed by the lidocaine-isoproterenol test dose, and saline followed by saline. HR was recorded every 20 s and T wave amplitude of lead II was continuously recorded. All patients receiving the bupivacaine-epinephrine test dose and none receiving saline met the HR (positive if ≥10 bpm increase) and T wave criteria (positive if ≥25% increase in amplitude). The isoproterenol-containing test dose produced positive responses based only on the HR criterion with or without atropine pretreatment. Our results indicate that HR and T wave changes are useful if a bupivacaine-epinephrine test dose is used and that HR is the only useful indicator if an isoproterenol-containing test dose is used in sevoflurane-anesthetized children. Implications To determine if an epidurally administered local anesthetic has been unintentionally injected into a blood vessel, a small dose of epinephrine or isoproterenol may be added to a local anesthetic. We found that an increase in heart rate ≥10 bpm and an increase in T wave amplitude of lead II ≥25% are useful indicators for detecting accidental intravascular injection of an epinephrine-containing test dose in sevoflurane-anesthetized children, whereas only a heart rate change is a reliable diagnostic tool if an isoproterenol-containing test dose is used.

Cardiovascular criteria for epidural test dosing in sevoflurane- and halothane-anesthetized children.

This study was designed to determine the detectability of a simulated IV test dose in children during administration of general anesthesia by using heart rate (HR), systolic blood pressure (SBP), and T wave criterion. Forty-two children (0.5-8 yr old) received an IV injection containing epinephrine 0.5 microg/kg and another IV injection containing saline during either halothane or sevoflurane anesthesia administration at 1.0 minimum alveolar concentration in nitrous oxide. A positive test response was defined as a change in T wave amplitude >/=25%, SBP increase >/=15 mm Hg, and HR increase >/=10 bpm. By using the T wave, SBP, and HR criteria, a positive response rate to epinephrine was 100%, 95%, and 71%, respectively, during sevoflurane, and 90%, 71%, and 71%, respectively, during halothane anesthesia administration. These data suggest that the T wave criterion is superior to conventional hemodynamic criteria, and that sevoflurane attenuates T wave and SBP responses less than halothane; however, chronotropic responses are similar to halothane. We found a greater reliability of the T wave criterion over conventional hemodynamic criteria for detecting intravascular injection of a simulated epidural test dose. Sevoflurane may increase the likelihood of recognition of an accidental intravascular injection of epinephrine-containing solutions in clinical practice compared with halothane.