Incidence of epileptiform EEG activity in children during mask induction of anaesthesia with brief administration of 8% sevoflurane.

BACKGROUND: A high incidence of epileptiform activity in the electroencephalogram (EEG) was reported in children undergoing mask induction of anaesthesia with administration of high doses of sevoflurane for 5 minutes and longer. This study was performed to investigate whether reducing the time of exposure to a high inhaled sevoflurane concentration would affect the incidence of epileptiform EEG activity. It was hypothesized that no epileptiform activity would occur, when the inhaled sevoflurane concentration would be reduced from 8% to 4% immediately after the loss of consciousness. METHODOLOGY/PRINCIPAL FINDINGS: 70 children (age 7-96 months, ASA I-II, premedication with midazolam) were anaesthetized with 8% sevoflurane in 100% oxygen via face mask. Immediately after loss of consciousness, the sevoflurane concentration was reduced to 4%. EEGs were recorded continuously and were later analyzed visually with regard to epileptiform EEG patterns. Sevoflurane at a concentration of 8% was given for 1.2 ± 0.4 min (mean ± SD). In 14 children (20%) epileptiform EEG patterns without motor manifestations were observed (delta with spikes (DSP), rhythmic polyspikes (PSR), epileptiform discharges (PED) in 10, 10, 4 children (14%, 14%, 6%)). 38 children (54%) had slow, rhythmic delta waves with high amplitudes (DS) appearing on average before DSP. CONCLUSIONS/SIGNIFICANCE: The hypothesis that no epileptiform potentials would occur during induction of anaesthesia with a reduction of the inspired sevoflurane concentration from 8% to 4% directly after LOC was not proved. Even if 8% sevoflurane is administered only briefly for induction of anaesthesia, epileptiform EEG activity may be observed in children despite premedication with midazolam.

Comparison of transpulmonary thermodilution and ultrasound dilution technique: novel insights into volumetric parameters from an animal model.

Especially in critically ill children with cardiac diseases, fluid management and monitoring of cardiovascular function are essential. Ultrasound dilution technique (UDT) was recently introduced to measure cardiac output (CO) and volumetric parameters, such as intrathoracic and end-diastolic blood volume. We compared UDT with the well-established transpulmonary thermodilution (TPTD) method (PiCCO) for determining CO measurements and derived volumes in a juvenile animal model. Experiments were performed in 18 ventilated, anesthetized piglets during normovolemia and after isovolemic hemodilution. At baseline and 20 min after each step of isovolemic hemodilution, 3 independent measurements of CO and volumetric parameters were conducted with TPTD and UDT, consecutively, under hemodynamically stable conditions. We observed comparable results for CO measurements with both methods (mean 1.98 l/min; range 1.12-2.87) with a percentage error of 17.3% (r = 0.92, mean bias = 0.28 l/min). Global end-diastolic volume (GEDV) and intrathoracic blood volume (ITBV) by TPTD were almost two times greater than analogous volumes [central blood volume (CBV); total end-diastolic volume (TEDV)] quantified by UDT (CBV = 0.58 × ITBV + 27.1 ml; TEDV = 0.48 × GEDV + 23.1 ml). CO measurements by UDT were found to be equivalent and hence interchangeable with TPTD. Discrepancies in volumetric parameters could either be due to the underlying algorithm or different types of indicators (diffusible vs. nondiffusible). Compared with the anatomically defined heart volume, TPTD seems to overestimate end-diastolic volumes. Future studies will be necessary to assign these results to critically ill children and to validate volumetric parameters with reference techniques.

Isovolaemic hemodilution with gelatin and hydroxyethylstarch 130/0.42: effects on hemostasis in piglets.

OBJECTIVES: Artificial colloids, frequently used to prevent hemorrhagic shock in children, impair blood coagulation. To determine the impact of acute isovolaemic hemodilution with artificial colloids on clot formation, we conducted an experimental study in a pediatric animal model. METHODS: Fifteen piglets underwent hemorrhage by withdrawing 40 ml·kg(-1) of blood volume in steps of 10 ml·kg(-1) each within 1 hour. After each withdrawal, the blood loss was randomly compensated by administering 4% gelatin (GEL) or hydroxylethyl starch 130/0.42 (HES) in a ratio of 1 : 1, or isotonic crystalloid solution (ICS) in a ratio of 1 : 4 for isovolaemic hemodilution. Quality of clot formation and platelet function was measured using Thrombelastometry (ROTEM(®)) and Multiple electrode impedance aggregometry (Multiplate(®)) after 10, 20, and 40 ml·kg(-1) blood replacement. RESULTS: Moderate hemodilution (10-20 ml·kg(-1) blood replacement) caused no significant differences among groups (e.g. INTEM(®)-MCF after 20 ml·kg(-1) blood replacement (ICS vs GEL vs HES, P > 0.05). Profound hemodilution with 40 ml·kg(-1) blood replacement showed a significant difference between ICS and both colloids (P < 0.05), but no significant differences between GEL and HES. CONCLUSIONS: Impairment of clot formation by moderate isovolaemic hemodilution did not significantly differ between ICS, GEL, and HES. Profound hemodilution of more than 50% of the estimated blood volume with GEL and HES caused significant impairment of clot formation in comparison to ICS and has to be considered when using high amounts of these synthetic colloids.

Single-lung ventilation with carbon dioxide hemipneumothorax: hemodynamic and respiratory effects in piglets.

OBJECTIVES: Video-assisted thoracoscopic surgery (VATS) has become a standard procedure in pediatric surgery. To facilitate surgical access, the dependent lung has to collapse using intrathoracic carbon dioxide insufflation and/or single-lung ventilation. These procedures can induce hemodynamic deteriorations in adults. The potential impacts of single-lung ventilation in combination with capnothorax on hemodynamics in infants have never been studied before. AIM: We conducted a randomized experimental study focusing on hemodynamic and respiratory changes during single-lung ventilation with or without capnothorax in a pediatric animal model. METHODS: Twelve piglets were randomly assigned to receive single-lung ventilation with (SLV-CO(2) ) or without (SLV) capnothorax with an insufflation pressure of 5 mmHg for a period of two hours. Before, during, and after single-lung ventilation, hemodynamic and respiratory parameters were measured. RESULTS: Although mean arterial pressure remained stable during the course of the study and no critical incidents were monitored, cardiac index (CI) decreased significantly with SLV-CO(2) (baseline 3.6 ± 1.6 l · min(-1) · m(-2) vs 2.9 ± 1.1 l · min(-1) · m(-2) at 120 min, P < 0.05). Furthermore, global end-diastolic volume and intrathoracic blood volume (ITBV) decreased as well significantly with SLV-CO(2) , causing a significant between-group difference in ITBV (P < 0.05). CONCLUSIONS: Despite a decrease in CI and preload parameters, the combination of single-lung ventilation and low-pressure capnothorax was well tolerated in piglets and could justify further clinical studies to be performed in infants and children focusing on hemodynamic and respiratory changes during VATS.

First experiences with intraoperative Levosimendan in pediatric cardiac surgery.

Levosimendan is a calcium-sensitizing agent with effective inotropic properties. It has been shown to improve cardiac function, hemodynamic performance, and survival in adults with severe heart failure. However, the effect of Levosimendan in pediatric cardiac surgery has not yet been investigated. Thus, we report on our experience with the intraoperative application of Levosimendan in seven infants (body weight range 2.6-6.3 kg) with severe myocardial dysfunction after complex congenital heart surgery. During the administration of Levosimendan, the heart rate, mean arterial blood pressure, and central venous pressure did not change. The mean arterial lactate level significantly decreased 24 and 48 h after the first infusion compared to baseline. Central venous oxygen saturation increased significantly 24 and 48 h after the onset of Levosimendan infusion. We found intraoperatively administered Levosimendan to be well tolerated in the seven infants with severe myocardial dysfunction after complex congenital heart surgery. Levosimendan is a new rescue drug which has beneficial effects, even in pediatric cardiac surgery.

Alteration of anion gap and strong ion difference caused by hydroxyethyl starch 6% (130/0.42) and gelatin 4% in children.

BACKGROUND: Synthetic colloid administration is a common practice for preventing perioperative hypovolemia and consecutive circulatory failure in children. This prospective, randomized study was conducted to investigate the effects of two different unbalanced synthetic colloid solutions on acid-base equilibrium in children. METHODS: Fifty pediatric patients (aged 0-12 years) scheduled for major pediatric surgery were randomized to receive either 10 ml x kg(-1) of 6% hydroxyethyl starch solution 130/0.42 (HES) or 4% modified fluid gelatin (GEL) to maintain adequate systemic hemodynamics. Before and after colloid administration, a blood sample was collected to analyze hemoglobin, hematocrit, electrolytes, and acid-base parameters. The anion gap and the strong ion difference (SID) were calculated using standard formulas. RESULTS: Both HES and GEL administration caused a significant increase in plasma chloride concentration (P < 0.01) and an accompanying decrease in SID (P < 0.01). In the HES group, the anion gap decreased significantly (P < 0.01) whereas the anion gap remained stable in the GEL group. In both groups, initial actual base excess and pH did not change significantly after colloid administration. CONCLUSIONS: Moderate intraoperative plasma replacement with unbalanced synthetic colloids HES and GEL leads to a decrease in SID and, in the case of HES, to a significant decrease in the anion gap in children. These alterations may result in a possible misinterpretation when the anion gap and SID are used for differential diagnosis of metabolic disturbances during major pediatric surgery.

Bicarbonate buffered ultrafiltration leads to a physiologic priming solution in pediatric cardiac surgery.

Pediatric cardiopulmonary bypass (CPB) involves a high ratio of priming blood volume to patient blood volume. The composition of packed red blood cells (RBCs) is very unphysiological in terms of acid-base, electrolyte and metabolite values. Therefore, we tested the hypothesis whether ultrafiltration of the prime and replacement with bicarbonate buffered hemofiltration solution (BB-HS) is sufficient for reducing the metabolic load and reaching a physiologic state. For planned surgery of congenital heart defects with cardiopulmonary bypass, 20 CPB circuits were primed with BB-HS, gelatin and 1 unit of RBCs. The fluid was hemofiltrated using an ultrahemofilter at 300 ml/min until approximately 1000 ml of ultrafiltrate was restored with BB-HS. Blood gas analyses were obtained from the priming blood, once before and once after bicarbonate buffered ultrafiltration (BBUF). The measured substrates decreased significantly (P<0.001) after BBUF (glucose from 13.0+/-2.6 to 6.3+/-1.0 and lactate from 3.8+/-1.5 to 2.3+/-1.0 mmol/l). Acid-base parameters increased (P<0.001) to normal or high normal values (pH from 7.01+/-0.09 to 7.68+/-0.12; HCO(3) from 12.1+/-2.4 to 25.4+/-3.6 mmol/l and BE from -15.4+/-3.6 to -0.8+/-3.7 mmol/l). Even the electrolytes sodium, potassium and calcium changed significantly (P<0.001) toward the physiologic range. BBUF is an efficient method of reducing the metabolic load of priming. After BBUF, even the electrolyte and acid-base balance reached a physiologic state, which is important for minimizing electrolyte and acid-base disturbances after initiation of CPB.

Complex myograph allows the examination of complex muscle contractions for the assessment of muscle force, shortening, velocity, and work in vivo.

BACKGROUND: The devices used for in vivo examination of muscle contractions assess only pure force contractions and the so-called isokinetic contractions. In isokinetic experiments, the extremity and its muscle are artificially moved with constant velocity by the measuring device, while a tetanic contraction is induced in the muscle, either by electrical stimulation or by maximal voluntary activation. With these systems, experiments cannot be performed at pre-defined, constant muscle length, single contractions cannot be evaluated individually and the separate examination of the isometric and the isotonic components of single contractions is not possible. METHODS: The myograph presented in our study has two newly developed technical units, i.e. a). a counterforce unit which can load the muscle with an adjustable, but constant force and b). a length-adjusting unit which allows for both the stretching and the contraction length to be infinitely adjustable independently of one another. The two units support the examination of complex types of contraction and store the counterforce and length-adjusting settings, so that these conditions may be accurately reapplied in later sessions. RESULTS: The measurement examples presented show that the muscle can be brought to every possible pre-stretching length and that single isotonic or complex isometric-isotonic contractions may be performed at every length. The applied forces act during different phases of contraction, resulting into different pre- and after-loads that can be kept constant - uninfluenced by the contraction. Maximal values for force, shortening, velocity and work may be obtained for individual muscles. This offers the possibility to obtain information on the muscle status and to monitor its changes under non-invasive measurement conditions. CONCLUSION: With the Complex Myograph, the whole spectrum of a muscle's mechanical characteristics may be assessed.

Hydroxyethyl starch 130/0.42/6:1 for perioperative plasma volume replacement in children: preliminary results of a European Prospective Multicenter Observational Postauthorization Safety Study (PASS).

BACKGROUND: Several clinical studies have shown that hydroxyethyl starch (HES) may be as effective and safe as, but less expensive than, albumin when used for perioperative plasma volume replacement (PVR) in children. The new third generation HES 130/0.42 solution was designed to reduce adverse drug reactions (ADRs) and improve safety while maintaining efficacy. Therefore, the objective of this prospective multicenter observational postauthorization safety study (PASS) was to evaluate the perioperative use of HES 130/0.42 in 1000 children with a particular focus on possible ADRs. METHODS: Approximately 300 of 1000 pediatric patients aged up to 12 years with ASA risk scores of I-III receiving perioperative HES 130/0.42 (Venofundin 6%; Braun, Melsungen, Germany) should be enrolled for interims analysis in the first year. The statistical sample size calculation showed that this number of patients would be sufficient to detect a 1% incidence of ADRs. Following approval by local ethics committee, patient demographics, data relating to HES 130/0.42 use, the procedures performed, anesthesia, and ADRs were documented with a particular focus on cardiovascular stability, hemodilution, acid-base balance, renal function, blood coagulation, and hypersensitivity. RESULTS: Three hundred and sixteen children (ASA I-III, age 3 +/- 3.4 [range, day of birth-12 years], body weight 13 +/- 10.5 [range, 1.1-60 kg]) were studied at five centers in Germany, Austria, and Italy from May 2006 until August 2007. Forty-five percent of the patients underwent abdominal surgery, 12.4% urologic procedures, 11.4% thoracic surgery, 7.6% orthopedic procedures, and 7% cardiovascular surgery. The mean volume of infused HES 130/0.42 was 11 +/- 4.8 ml x kg(-1) (range, 5-42). Cardiovascular stability was maintained in all cases. After HES infusion, hemoglobin (11.5 vs 10.25 g x dl(-1)), base excess (-2 vs -2.7 mmol x l(-1)), anion gap (12.9 vs 11.2 mmol x l(-1)), and strong ion difference (34.3 vs 31.4 mmol x L(-1)) decreased, and chloride (105.7 vs 107.8 mmol x l(-1)) increased significantly (P < 0.05). No serious ADRs (i.e., anaphylactoid reaction, renal failure, clotting disorders) were observed. CONCLUSION: Moderate doses of HES 130/0.42 help to maintain cardiovascular stability and lead to only moderate changes in hemoglobin concentration and acid-base balance in children. The probability of serious ADRs is lower than 1%. Therefore, HES 130/0.42 for PVR seems to be safe and effective even in neonates and small infants with normal renal function and coagulation.

Plasma volume replacement with HES 130/0.42 obviates negative side effects of pneumoperitoneum in piglets.

BACKGROUND: Evidence-based guidelines on optimal perioperative fluid management in infants have not been established. Recent randomized trials in major abdominal surgery in adults suggest that large volumes of fluid may increase morbidity and hospital stay. Our own clinical experience in infants undergoing laparoscopic surgery is different. So the aim of this study was to compare a crystalloid vs a plasma volume stabilizing fluid management regime during prolonged pneumoperitoneum (PP) in an experimental setting. METHODS: Fifteen German landrace piglets were randomized to one of the following treatment groups: control (no PP, 5 ml x kg(-1) x h(-1) electrolyte solution); crystalloid (180 min of PP, 5 ml x kg(-1) x h(-1) electrolyte solution); colloid (180 min of PP, single bolus of 5 ml x kg(-1) followed by 5 ml x kg(-1) x h(-1) hydroxyethyl starch 130/0.42/6:2). After decompression, monitoring was continued for a further 120 min. During the investigation, the hemodynamic situation including transpulmonary thermodilution and blood gases was monitored periodically. RESULTS: During the study, mean arterial pressure remained within the normal range in colloid-treated animals and controls, but was significantly lower in crystalloid-treated animals after decompression of PP. Cardiac output remained within the normal range in the colloid and control groups, but decreased in the crystalloid-treated animals. In the crystalloid group, the lactate concentrations were higher and base excess was lower than in the colloid and control groups at 240 and 300 min (study end). CONCLUSION: This study shows that the negative effects of prolonged PP on hemodynamics and acid-base balance can be obviated by a liberal plasma volume stabilization regimen with colloids.

Whole blood coagulation measured by modified thrombelastography (ROTEM) is impaired in infants with congenital heart diseases.

Patients with congenital heart disease (CHD) often do have a variety of coagulation abnormalities that results in bleeding diathesis. Our study aimed to determine the impact of cyanosis and CHD on modified thrombelastography parameters, compared with children without CHD. Preoperative blood samples were taken for TEM analyses from a total of 51 infants scheduled for surgery. The following groups were examined: normal patients without CHD, acyanotic patients with acyanotic CHD, and cyanotic patients with CHD and with preoperative hemoglobin values higher than 15 g dl(-1). Mean values of all patient groups as well as all individual values of normal patients were within their normal ranges. Within these limits, however, clots were significantly inferior in cyanotic patients (worse mean values of eight out of 10 measured TEM parameters representing the intrinsic, extrinsic, and plasmatic pathways of coagulation) and in acyanotic patients (two out of 10 TEM parameters). Individually, pathological TEM parameters were found in seven (41%) cyanotic patients (P=0.003; vs. normal patients) and in three (17%) acyanotic patients (P=0.01). More than one abnormal TEM coagulation parameter was found in four patients, all of them cyanotic patients. Hyperfibrinolysis was detected in one patient, a cyanotic patient. The present investigation confirms previous findings that in patients with CHD the heart defect itself compromises coagulation monitored with TEM, but in addition, we demonstrate that cyanosis and/or polycythemia exert the essential negative impact on hemostasis. Preoperative hyperfibrinolysis detected with TEM seems to play no important role.

Tumor lysis associated with dexamethasone use in a child with leukemia.

Postoperative nausea and vomiting (PONV) occurs in every third patient undergoing general anesthesia without PONV prophylaxis. Antiemetic prophylaxis with dexamethasone is commonly used in patients at moderate risk. We present a case in which PONV prophylaxis with a single dose of dexamethasone led to tumor lysis in a patient with acute leukemia. In case of a cancer patient at moderate risk for PONV, the anesthesiologist should contact the oncologist first, or use other antiemetic drugs such as antiserotoninergic agents for PONV prophylaxis.

Comparison of electrical velocimetry and transpulmonary thermodilution for measuring cardiac output in piglets.

BACKGROUND: Monitoring of cardiovascular function is essential during major pediatric and pediatric cardiac surgery. Invasive monitoring of cardiac output (CO) and oxygen delivery is expensive and sometimes associated with adverse events. Therefore, we investigated the accuracy of a new noninvasive CO monitoring device using electrical velocimetry (EV) in comparison with the more invasive transpulmonary thermodilution (TPTD) method. METHODS: In five fasted, anesthetized and mechanically ventilated piglets, CO was measured simultaneously using EV and TPTD under normal conditions, volume loading, inotropic support and exsanguination. RESULTS: In five piglets, 169 measurements could be performed. The correlations between EV-CO and TPTD-CO were significant for absolute values (P < 0.0001, r = 0.82) and relative changes from baseline (P < 0.0001, r = 0.93). The receiver operating characteristic (ROC) curve analysis of the relative changes of the EV-CO values in relation to the first EV-CO measurement showed a sensitivity of 91% and specificity of 94% (AUC 0.974, 95% CI 0.96-0.99). Changes in TPTD-CO greater than 15% lead to a change of EV-CO in the same direction in 93%. Bland-Altman analysis showed a mean difference between the two methods of -0.63 l x min(-1) with an sd of 0.64 l x min(-1). The lower and upper limits of agreement were -1.88 and 0.62 l x min(-1), percentage limit of agreement was +/-82.8%. CONCLUSIONS: The results show that EV is a safe, simple, noninvasive and cost-effective method for continuous trend monitoring of CO in piglets. The agreement of the EV-CO with TPTD-CO is not good enough to replace the standard method in our animal model. A correction factor for body habitus in piglets may be beneficial.

The pediatric cardiac patient presenting for noncardiac surgery.

PURPOSE OF REVIEW: To summarize results of recent papers and discuss current trends concerning anesthesia in children with congenital heart disease presenting for noncardiac surgery. RECENT FINDINGS: Children with congenital heart disease have a significant incremental risk when presenting for minor or major surgery. It is a current trend that noncardiac surgery should be performed in pediatric centers, which have anesthesiologists and pediatricians familiar with the multiple specialties of children with congenital heart disease. A careful preoperative evaluation using a multidisciplinary approach is of great importance. In recent studies and case reports, the safe use of newer anesthetic agents, such as sevoflurane or desflurane, was reported in combination with opioids or regional blocks. In addition to standard monitors, invasive monitoring should be considered liberally perioperatively in patients with limited hemodynamic reserve and with major surgery. Several case reports reported that laparoscopic surgery was successfully performed even in high-risk patients with congenital heart disease. SUMMARY: Careful preoperative evaluation, experienced anesthesiologists, suitable anesthetic agents and techniques, and the liberal use of invasive monitoring are integral parts of safe and effective anesthetic care in children with congenital heart disease. Future studies have to show whether laparoscopic surgery may be beneficial in this special subgroup of patients.