The hemodynamic effects of pediatric caudal anesthesia assessed by esophageal Doppler

Analgesia strategy for inguinal hernia repair in children: a systematic review and network meta-analysis of randomized clinical trials based on regional blocks

Background and objective

Despite its acknowledged benefits, the selection of an optimal regional block for analgesia pediatric hernia surgery remains a subject of debate. This study endeavored to conduct a network meta-analysis and systematic review of randomized clinical trials, aiming to amalgamate insights from both direct and indirect comparisons concerning the analgesic effectiveness and safety of various regional blocks post-inguinal hernia repair in children.

Method

A comprehensive literature search was performed across PubMed, EMBASE, Web of Science, and the Cochrane Library up to 12 November 2022 by two independent reviewers, employing a standardized protocol. The inclusion criteria encompassed randomized trials focusing on children undergoing inguinal hernia repair utilizing either local infiltration analgesia or regional analgesia. The primary outcomes assessed were pain scores at 2, 6, and 24 h post-operation.

Results

The initial search yielded 281 records relating to 1,137 patients. The analysis of ranking probability indicated that Paravertebral Block (PVB) holds the highest likelihood (88% and 48%) of being the most effective in alleviating pain at 2 h and 6 h post-surgery. Trans vs. Abdominis Plane Block (TAPB) emerged as the superior choice for mitigating pain (83%) and decreasing morphine consumption (93%) at 24 h following the operation. Local Anesthetic Infiltration (LAI) was identified as the most effective in shortening the hospital stay, with a 90% probability.

Conclusions

Regional anesthesia significantly enhances postoperative pain management in pediatric inguinal hernia repair surgery. For short-term postoperative pain relief, PVB emerges as the most effective technique. Meanwhile, TAPB provides more prolonged analgesia. Although TAPB does not exhibit a pronounced advantage in short-term analgesia, its simplicity and the absence of a need for a special position render it a viable option. However, the interpretation of these results should be approached with caution due to the presence of limited data and heterogeneity.

Systematic Review Registration

PROSPERO (CRD42022376435; www.crd.york.ac.uk/prospero).

Effects of awake caudal anesthesia on mean arterial blood pressure in very low birthweight infants

Background

Intraoperative blood pressure is a relevant variable for postoperative outcome in infants undergoing surgical procedures. It is therefore important to know whether the type of anesthesia has an impact on intraoperative blood pressure management in very low birth weight infants. Here, we retrospectively analyzed intraoperative blood pressure in very low birthweight infants receiving either awake caudal anesthesia without sedation, or caudal block in combination with general anesthesia, both for open inguinal hernia repair.

Methods

Ethical approval was provided by the University of Tuebingen Ethical Committee on 05/29/2018 with the project number 403/2018BO2. Patient records of infants admitted by the neonatologist (median age at birth 31.1 ± 3.5 weeks, median weight at birth 1240 ± 521 g) which were scheduled for inguinal hernia repair were retrospectively evaluated for the course of mean arterial blood pressure and perioperative interventions to stabilize blood pressure. A total of 42 patients were included, 16 patients (11 boys, 5 girls) received awake caudal anesthesia, 26 patients (22 boys, 4 girls) a combination of general anesthesia and caudal block.

Results

Approximately 3% of the measured mean arterial blood pressure values in the caudal anesthesia group were below a critical margin of 35 mmHg, in contrast to 47% in the combined anesthesia group (p < 0.001). Patients in the latter group showed a significantly larger drop of mean arterial blood pressure below 35 mmHg (4.7 ± 2.7 mmHg vs. 1.9 ± 1.6 mmHg; p < 0.005) and a significantly longer time of mean arterial blood pressure below 35 mmHg (25.6 ± 26.0 min vs. 0.9 ± 2.3 min; p < 0.001), although they received more volume and vasopressor boluses for stabilization (27 ± 14.8 ml vs. 10 ± 4.1 ml; p < 0.01 and 0.15 ± 0.06 ml vs. 0 ml of cafedrine/theoadrenaline; p < 0.001).

Conclusions

The study indicates that the use of caudal block as stand alone procedure for inguinal hernia repair in very low birthweight infants might be advantageous in preventing critical blood pressure drops compared to a combination of caudal block with general anesthesia.

Caudal block with 3 mg/Kg Bupivacaine for intraabdominal surgery in pediatric patients: a randomized study

Background: Caudal block with the use of an adequate dose of bupivacaine, and combined with a general anesthesia (GA) provides intra-operative anesthesia and postoperative analgesia. No study has examined the use of 3 mg/Kg bupivacaine for intra-abdominal surgery in pediatric patients in clinical practice.

Objective: Compare the effectiveness of three mg/Kg bupivacaine administered as 1.2 mL/Kg 0.25% bupivacaine and 1.5 mL/Kg 0.2% bupivacaine for caudal block in pediatric patients undergoing intra-abdominal surgery.

Methods: In a randomized, double-blinded clinical trial, patients (age: 6 months -7 years) were randomly assigned into one of two groups (n= 40) to receive a caudal block with either 1.2 mL/Kg 0.25% bupivacaine (group A) or 1.5 mL/Kg 0.2% bupivacaine (group B), with morphine 50 μg/Kg. The effectiveness of intra-operative anesthesia, complications, and requirements for post-operative analgesia were evaluated.

Results: Data were available for 74 pediatric patients. There were no significant differences between the two groups in baseline characteristics. Intra-operatively, the numbers of patients who required a rescue analgesic were comparable between the groups (67% in group A and 63% in group B). The numbers of patients who required a muscle relaxant were also comparable between groups (49% in group A and 57% in group B). The time from discontinuation of the volatile anesthetic to extubation was significantly shorter in group B (9.5±1.1 minutes) than group A (14.3±0.9 minutes), p < 0.01. The time from initial caudal block to the first analgesic required in the recovery room was significantly longer in group B (202±45 minutes) than in group A (149±27 minutes). The time from the caudal block to the first analgesic required in the ward was significantly longer in group B (10.4±3.1 hours) than in group A (8.2±2.0 hours). Overall fentanyl requirements were comparable between groups, 52.5±2.0 μg in group A and 49.5±3.0 μg in group B.

Conclusion: Caudal block by either 1.2 mL/Kg 0.25% bupivacaine plus morphine 50 μg/Kg or 1.5 mL/Kg 0.2% bupivacaine plus morphine 50 μg/Kg provided effectively equivalent intra-operative analgesia and surgical relaxation. However, a caudal block with 1.5 mL/Kg 0.2% bupivacaine plus morphine 50 μg/Kg provided superior prolonged analgesic advantages compared with 1.2 mL/Kg 0.25% bupivacaine plus morphine 50 μg/Kg in pediatric patients undergoing intra-abdominal surgery.

Postoperative analgesia in pediatric herniotomy - Comparison of caudal bupivacaine to bupivacaine infiltration with diclofenac suppository

CONTEXT

Perioperative analgesia in paediatric herniotomies demand safe, effective and less invasive strategies. Local infiltration with Bupivacaine, rectal Diclofenac and caudal Bupivacaine are widely used for pain relief.

AIMS

To compare the analgesic effects of caudal epidural using 1 mlkg(-1) of 0.25% Bupivacaine against a combination of local infiltration 0.25% Bupivacaine 0.5 mlkg(-1) with Diclofenac suppository 2 mgkg(-1) in the management of post-operative pain following paediatric inguinal herniotomy.

SETTINGS AND DESIGN

This is an observational study from a tertiary care teaching hospital.

METHODS AND MATERIAL

A total of 60 children for elective unilateral inguinal herniotomy were assigned to two groups of 30 each. Patients who received caudal block with 1 mlkg(-1) of 0.25% Bupivacaine were allocated to Group A and who received Diclofenac suppository 2 mgkg(-1) and infiltration with 0.25% Bupivacaine 0.5 mlkg(-1) were allocated to Group B. Post operative Pain was assessed using Hannallah's modified objective pain scale. At score ≥3 rescue analgesic oral Paracetamol 15 mgkg(-1) was given. Pain was assessed at 0,15,30,45,60 minutes and half hourly thereafter until 8 hours following surgery or until patient requires rescue analgesic whichever happens first.

STATISTICAL ANALYSIS USED

Employed SPSS software. Data was analysed using sample t test and P-value was calculated.

RESULTS

The demographic profile was comparable between two groups. The mean analgesic duration in group A and group B was 228.5 and 331.0 minutes respectively and is found to be statistically significant (P < 0.05).

CONCLUSIONS

Diclofenac suppository with local infiltration is a less invasive and effective alternative to caudal Bupivacaine for analgesia in paediatric herniotomy.

The Use of Epinephrine in Caudal Anesthesia Increases Stroke Volume and Cardiac Output in Children

BACKGROUND AND OBJECTIVES

Caudal anesthesia is a common and effective regional anesthesia technique in pediatric patients. The addition of epinephrine to local anesthetics in caudal anesthesia is a frequent practice; however, changes in hemodynamic and cardiac parameters produced by epinephrine in caudal anesthesia are not well studied. Using data collected with the ICON noninvasive cardiac output monitor, we examined the hemodynamic changes associated with the administration of epinephrine containing local anesthetics during caudal anesthesia in children.

METHODS

We performed a retrospective analysis of 40 patients who received caudal anesthesia among 402 patients from whom we prospectively collected continuous noninvasive cardiac output data using the ICON monitor, which estimates cardiac output by measuring changes in thoracic bioimpedance during the cardiac cycle. Twenty-three children received epinephrine with local anesthetic (ELA), and 17 children received only local anesthetic (OLA) in their caudal blocks. We compared heart rate (HR), stroke volume (SV), cardiac output (CO), and cardiac index (CI) changes from baseline before caudal injection to 1-minute intervals over 15 minutes after caudal injection for both ELA and OLA groups (Table, Supplemental Digital Content 1, http://links.lww.com/AAP/A179). We also performed subgroup analysis of the same parameters comparing both ELA and OLA groups in infants younger than 6 months and in children 6 months or older.

RESULTS

Stroke volume, CO, and CI are significantly increased after caudal injection in the ELA group compared with baseline values at caudal injection time. Conversely, there were no statistically significant changes in SV, CO, and CI in the OLA group. There were no significant HR or blood pressure changes observed in either the ELA or OLA group within 15 minutes compared with baseline caudal injection time. In infants younger than 6 months, no significant differences were found in HR, SV, and CI in children in the ELA group compared with the OLA group. In children 6 months or older, SV and CI increased significantly in the ELA group compared with the OLA group.

CONCLUSIONS

Epinephrine added to local anesthetic injected for caudal anesthesia produces significant increases in SV, CO, and CI in children. Stroke volume and CI changes from epinephrine added to local anesthetic for caudal anesthesia seem to take place only in children 6 months or older.

Unintentional epidural injection of 88 μg·kg(-1) of epinephrine

We report the effects of 88 μg·kg(-1) of epinephrine (1:10,000) injected into the caudal epidural space of a 42-week postconceptual age infant. No long-term neurological or cardiovascular sequelae occurred. Noninvasive cardiac output (CO) monitoring revealed increased CO, contractility, and stroke volume for about an hour, accompanied by a reduction in peripheral vascular resistance and a modest increase in pulse and blood pressure.

Effect of caudal block on sevoflurane requirement for lower limb surgery in children with cerebral palsy

BACKGROUND

Caudal block is a widely used technique for providing perioperative pain management in children. In this randomized double-blinded study, we evaluated the effects of preoperative caudal block on sevoflurane requirements in children with cerebral palsy (CP) undergoing lower limb surgery while bispectral index (BIS) values were maintained between 45 and 55.

METHODS

52 children undergoing Achilles-tendon lengthening were randomized to receive combined general-caudal anesthesia (caudal group, n = 27) or general anesthesia alone (control group, n = 25). Caudal block was performed with a single dose of 0.7 ml·kg(-1) of 1.0% lidocaine containing epinephrine at 5 μg·ml(-1). The control group received no preoperative caudal block. The endtidal sevoflurane concentrations (ET(sev)) were adjusted every minute to maintain the BIS values between 45 and 55.

RESULTS

The ET(sev) required to maintain the BIS values were not significantly different between the control and caudal groups after induction of anesthesia [2.1 (0.2) vs 2.2 (0.4); P = 0.773]. However, significantly higher ET(sev) was observed in the control group before surgical incision [2.0 (0.2) vs 1.8 (0.3); P = 0.013] and during the first 20 min after surgical incision [2.2 (0.3) vs 1.4 (0.3); P < 0.001]. There was no significant difference in BIS values between the control and caudal groups throughout the study period (P > 0.05). In the caudal group, the caudal block was successful in 25 of 27 (92.6%) patients.

CONCLUSIONS

Caudal block effectively reduced sevoflurane requirements by 36% compared to general anesthesia alone in children with CP undergoing lower limb surgery while BIS values were maintained between 45 and 55.

Does epidural analgesia delay the diagnosis of lower limb compartment syndrome in children?

One of the cardinal symptoms of compartment syndrome is pain. A literature review was undertaken in order to assess the association of epidural analgesia and compartment syndrome in children, whether epidural analgesia delays the diagnosis, and to identify patients who might be at risk. Evidence was sought to offer recommendations in the use of epidural analgesia in patients at risk of developing compartment syndrome of the lower limb. Increasing analgesic use, increasing/breakthrough pain and pain remote to the surgical site were identified as important early warning signs of impending compartment syndrome in the lower limb of a child with a working epidural. The presence of any should trigger immediate examination of the painful site, and active management of the situation (we have proposed one clinical pathway). Avoidance of dense sensory or motor block and unnecessary sensory blockade of areas remote to the surgical site allows full assessment of the child and may prevent any delay in diagnosis of compartment syndrome. Focusing on excluding the diagnosis of compartment syndrome rather than failure of analgesic modality is vital. In the pediatric cases reviewed there was no clear evidence that the presence of an epidural had delayed the diagnosis.

Intravascular ultrasound allows a hyperplasia diagnosis in vivo in rat as accurate as histomorphometry

OBJECTIVE AND MOTIVATION

Intravascular ultrasound (IVUS) allows in vivo invasive intra-luminal real-time examination of the arterial wall structure. In this study, we aimed to validate for the first time the in vivo IVUS performing as a diagnostic tool by comparison to the well-established histomorphometry approach, in the largely used rat model of carotid angioplasty model that mimics the angioplasty procedure in humans.

METHODS

Atherosclerotic lesions were allowed to develop during four weeks after balloon catheter inflation of the left carotid artery, whereas the intact right carotid artery was used as control. Four weeks after injury, a Boston Scientific 40MHz device to perform IVUS exams in vivo on both carotid arteries. Then, both carotid arteries were examined in vitro by histomorphometry and correlation between IVUS and histomorphometric parameters (plaque plus media cross-sectional areas [CSA] and eccentricity index) were researched.

RESULTS

After ANOVA analysis, comparative statistical analysis showed significant correlations between IVUS and histomorphometry when examining the intact right carotid artery (r=0.662 with p<0.003 for plaque plus media CSA; r=0.774 with p<0.002 for eccentricity index), but also when exploring the injured left carotid artery (r=0.805 with p<0.0001 for plaque plus media CSA; r=0.775 with p<0.002 for eccentricity index).

CONCLUSIONS AND OUTCOME

We report here for the first time the ability of IVUS to study therapeutic vascular effects in vivo in alive rats. This result is of major importance since it will allow this device to be used for restenosis drug testing in rat model of carotid angioplasty.

Hemodynamic effects of levobupivacaine after pediatric caudal anesthesia evaluated by transesophageal doppler

BACKGROUND

The aim of this study is to determine if there are significant differences in hemodynamic effects between combined general-regional anesthesia using levobupivacaine 0.25% 2 ml x kg(-1) via the caudal route in comparison with balanced general anesthesia using continuous infusion of remifentanil in young children undergoing genitourinary surgery.

PATIENTS AND METHODS

62 ASA I-II pediatric patients (12 female, 50 male) aged 6 months to 7 years undergoing genitourinary surgery were included in the study. Patients were randomly allocated into one of two groups of 31 patients each. Group Caud received caudal blockade with levobupivacaine 0.25% 2 mg x kg(-1) in combined general-regional anesthesia and Group Gen received balanced general anesthesia with remifentanil. The noninvasive hemodynamic parameters were measured in each group 5 min after induction of general anesthesia or caudal block (Tcaud), after further 5 min coincident with skin incision (Tsi), 10 min after skin incision (T10i), at the end of surgical procedure (Tend). The time between Tcaud and Tsi was 10 min and the measurements during the interval time T10i-Tend were performed every 15 min according to the duration of surgical procedures.

RESULTS

There was a decrease in all measured hemodynamic parameters at skin incision. The decreases occurred in both groups with those in the caudal group occurring at skin incision and those in the balanced anesthesia group occurring at 10 min after skin incision. These variations showed no significant differences for any of the stated outcomes; neither between the groups at each time point nor in the caudal in comparison with baseline measurements.

CONCLUSIONS

Using transesophageal Doppler no differences in hemodynamic parameters could be detected between balanced general anesthesia with either caudal levobupivacaine or remifentanil infusion. Both techniques showed good hemodynamic stability with only minor changes from baseline over time which are unlikely to be of clinical significance except possibly in patients with preexisting cardiovascular compromise. Other studies with noninvasive monitoring in a larger population are required to better understand the consequences of caudal blockade on CO and on regional blood flow in infants.

The hemodynamic effects of newborn caudal anesthesia assessed by transthoracic echocardiography: a randomized, double-blind, controlled study

BACKGROUND

Caudal anesthesia has been increasingly used in abdominal, urinary tract, and lower extremity surgery of infants. However, little was known about the hemodynamic effects of caudal anesthesia in them, especially in neonates. The purpose of this prospective study was designed to investigate the hemodynamic alterations by transthoracic echocardiography in newborn baby after caudal anesthesia with plain Bupivacaine or with epinephrine added Bupivacaine.

METHODS

Thirty full-term newborn infants scheduled for lower abdominal or urinary tract surgery were randomly allocated into three groups (n = 10 each) as follows: (i) GA group: general anesthesia with sevoflurane; (ii) GA+CP group: GA with sevoflurane, combined with caudal anesthesia of plain Bupivacaine (1.25 ml x kg(-1) of 0.2%); (iii) GA+CA group: sevoflurane GA combined with caudal anesthesia of epinephrine-added Bupivacaine (1.25 ml x kg(-1) of 0.2% Bupivacaine plus 1/200,000 epinephrine). Cardiac output (CO), arterial blood pressure, and heart rate were measured before (T-5) and 5(T5), 10(T10), 15(T15) min after performance of caudal anesthesia.

RESULTS

In GA group, no significant hemodynamic alteration was observed in comparison with T-5, except HR, which decreased by 7% at T15; In GA+CP group, compared with T-5, HR decreased significantly at T5, T10 and T15, respectively, by 6%, 7% and 10%. And also CO decreased significantly at T15 by 8% compared with T-5; In GA+CA group, no significant hemodynamic alteration was observed expect diastolic arterial blood, which decreased significantly at T15 by 10% compared with T-5; At T15, the larger decrease of systolic arterial blood in GA+CP group and GA+CA group vs (GA) group (P < 0.05).

CONCLUSIONS

The study shows the stability of hemodynamic variables during caudal anesthesia with Bupivacaine and with epinephrine-added Bupivacaine in newborn infants.

Continuous, non-invasive techniques to determine cardiac output in children after cardiac surgery: evaluation of transesophageal Doppler and electric velocimetry

BACKGROUND

Continuous and non-invasive measurement of cardiac output (CO) may contribute helpful information to the care and treatment of the critically ill pediatric patient. Different methods are available but their clinical verification is still a major problem.

AIM

Comparison of reliability and safety of two continuous non-invasive methods with transthoracic echocardiography (TTE) for CO measurement: electric velocimetry technique (EV, Aesculon) and transesophageal Doppler (TED, CardioQP). METHODS/MATERIAL: In 26 infants and children who had undergone corrective cardiac surgery at a median age of 3.5 (1-17) years CO and stroke volume (SV) were obtained by EV, TED and TTE. Each patient had five measurements on the first day after surgery, during mechanical ventilation and sedation.

RESULTS

Values for CO and SV from TED and EV correlated well with those of TTE (r = 0.85 and r = 0.88), but mean values were significantly lower than the values of TTE for TED (P = 0.02) and EV (P = 0.001). According to Bland-Altman analysis, bias was 0.36 l/min with a precision of 1.67 l/min for TED vs. TTE and 0.87 l/min (bias) with a precision of 3.26 l/min for EV vs. TTE. No severe adverse events were observed and the handling of both systems was easy in the sedated child.

CONCLUSIONS

In pediatric patients non-invasive measurement of CO and SV with TED and EV is useful for continuous monitoring after heart surgery. Both new methods seem to underestimate cardiac output in terms of absolute values. However, TED shows tolerable bias and precision and may be helpful for continuous CO monitoring in a deeply sedated and ventilated pediatric patient, e.g. in the operating room or intensive care unit.

The transesophageal Doppler and hemodynamic effects of epidural anesthesia in infants anesthetized with sevoflurane and sufentanil

BACKGROUND

It is thought that pediatric epidural anesthesia (EA) provides hemodynamic stability in children. However, when compared with information relating to adults, little is known about the hemodynamic effects of epidural EA on cardiac output (CO) in infants.

METHODS

Using transesophageal Doppler to monitor CO, we prospectively studied 14 infants <10 kg who were scheduled for abdominal surgery. During sevoflurane general anesthesia, CO transesophageal Doppler monitoring was performed before and after lumbar EA with 0.75 mL/kg of 0.25% bupivacaine and 1:200,000 adrenaline. CO, arterial blood pressure, and heart rate were measured before and 5, 15, and 20 min after performance of EA.

RESULTS

In patients anesthetized with sevoflurane and sufentanil, EA resulted in an increase in stroke volume by 29% (P < 0.0001) and a decrease in heart rate by 13% (P < 0.0001). EA also induced a significant decrease in systolic, diastolic, mean arterial blood pressure, and systemic vascular resistance by 11%, 18%, 15%, and 25%, respectively. Conversely, CO remained unchanged.

CONCLUSIONS

The increase in stroke volume observed is probably explained by optimization of afterload because of the sympathetic blockade induced by EA. These results confirm that EA provides hemodynamic stability in infants weighing <10 kg and supports the use of EA in this pediatric population.

Noninvasive cardiac output monitoring

PURPOSE OF REVIEW

In an effort to provide high-quality intensive care without increasing morbidity and possibly decreasing mortality, noninvasive means of monitoring hemodynamics have been developed. Recently, commercially available monitoring techniques have been afforded the intensivist for just this purpose. This review will discuss the various means available, their limitations and recent literature describing their clinical use in comparison with pulmonary artery catheterization.

RECENT FINDINGS

Each method has been tested clinically, some more so than others. The general consensus is that each method correlates well with pulmonary artery catheterization. Each method, however, has limitations. Users must be familiar with the limitations and aware of which method is most appropriate for their patients. In general, the derived data provided by the noninvasive methods parallel those of pulmonary artery catheterization, with the exclusion of some commonly used variables (i.e. mixed venous oxygen, wedge pressure). Some novel variables derived from the new techniques can provide analogous information to that gathered from the pulmonary artery catheter.

SUMMARY

In summary, the methods commercially available today to measure hemodynamics in a noninvasive fashion offer good correlation to the traditional data derived from pulmonary artery catheterization. Pulmonary artery catheterization is considered, by most, to be the standard by which to compare other methods and will most likely remain so. This is due to a long history of reliance and clinical familiarity with its use. Additional clinical studies will need to be performed in a heterogeneous population of patients (trauma, burn, sepsis etc.) to enable better determination of reliability and limitations in various clinical scenarios. Overcoming the clinician's personal preference to rely on traditional pressure-derived data will also be a large obstacle to overcome.

Small-dose bupivacaine-sufentanil prevents cardiac output modifications after spinal anesthesia

Spinal injection of small-dose (SD) bupivacaine decreases the likelihood of hypotension compared with large-dose (LD) bupivacaine. We assumed that a SD of bupivacaine could also prevent the decrease in cardiac output (CO). Patients undergoing elective urologic, lower abdominal, or lower limb surgery under spinal anesthesia were included in this prospective randomized study. Spinal injection consisted of 5 mug of sufentanil and either SD (7.5 mg of hyperbaric bupivacaine with glucosemonohydrate 80 mg/mL; n = 19 patients) or LD (12.5 mg of hyperbaric bupivacaine with glucosemonohydrate 80 mg/mL; n = 19 patients). CO (impedance cardiography), arterial blood pressure, and heart rate) were measured at 1 min before performance of spinal block and 2, 10, and 30 min after the intrathecal injection. Sensory level was also assessed at 30 min. CO was higher in the SD group as compared with the LD group from 2 min to 30 min after spinal anesthesia. Moreover, CO increased at 2 min in the SD group and decreased at 10 and 30 min in the LD group compared with baseline value. In conclusion, SD bupivacaine provides successful anesthesia and gives better CO stability than LD.

Noninvasive techniques for measurements of cardiac output

PURPOSE OF REVIEW

Measuring stroke volume or cardiac output is of paramount importance for the management of critically ill patients in the intensive care unit, or 'high risk' surgical patients in the operating room. The new noninvasive techniques are gaining acceptance among intensivists and anesthesiologists who have been trained almost exclusively in the pulmonary artery catheter and the thermodilution technique.

RECENT FINDINGS

The present review focuses on the recent publications related to esophageal Doppler, Fick principle applied to carbon dioxide associated with partial rebreathing, and pulse contour analysis. Recent validation studies have confirmed the previous findings: all three methods provide reliable estimations of cardiac output and its variations. There is not a single method standing out and ruling out the others. Many investigators are now using one of the 'noninvasive' monitors to measure cardiac output in clinical or experimental studies.

SUMMARY

By making cardiac output easily measurable in various settings, these techniques should all contribute to improve hemodynamic management in critically ill or high-risk surgical patients.

The effects of spread of block and adrenaline on cardiac output after epidural anesthesia in young children: a randomized, double-blind, prospective study

Epidural anesthesia is considered to be without significant hemodynamic consequence in young children. However, conversely to adults, few studies have investigated cardiac output. Using transesophageal Doppler monitoring of cardiac output, we prospectively investigated hemodynamic alterations in 48 children (median age, 22.5 mo) receiving sevoflurane general anesthesia combined with caudal or thoracolumbar epidural anesthesia. They were randomly assigned to receive 0.8 mL/kg of plain local anesthetic mixture (lidocaine 1% + bupivacaine 0.25% (50/50) + 1 microg/mL of fentanyl) or 1 mL/kg of the same mixture with 5 microg/mL of adrenaline. No significant hemodynamic alteration was elicited in caudal and thoracolumbar groups receiving the plain mixture except a moderate decrease in heart rate. Conversely, a mixture with adrenaline added provoked a significant decrease in mean arterial blood pressure by 14% and 17%, in systemic vascular resistance by 24% and 40%, and an increase in cardiac output by 20% and 34% in caudal and thoracolumbar groups, respectively. The adrenaline effect was greater by the thoracolumbar than the caudal approach. In young children, epidural anesthesia induces an increase in cardiac output only when adrenaline is added to local anesthetics, probably through its systemic absorption from the epidural space.

IMPLICATIONS

Epidural anesthesia may induce significant hemodynamic changes, well documented in adults. Using noninvasive hemodynamic monitoring in children, we reported an increase in cardiac output and a decrease in arterial blood pressure only when epinephrine was added to epidurally-injected local anesthetics.