Epidural catheter placement in children: comparing a novel approach using ultrasound guidance and a standard loss-of-resistance technique.

BACKGROUND: We report a prospective, randomized study to evaluate ultrasound guidance for epidural catheter placement in children 0-6 yr of age. METHODS: Epidural catheters were placed at lumbar or thoracic cord levels in 64 children undergoing major surgery, using either ultrasonography or loss-of-resistance (LOR) for guidance. Using a 5-10 MHz linear ultrasound probe, the neuraxial structures were identified, the skin-epidural depth and epidural space was measured, the advancing epidural catheter visualized, and the spread of local anaesthetic verifying catheter position was confirmed. Epidural placement procedures were analysed for bone contacts and speed of execution. Children under 6 months were analysed separately. RESULTS: Epidural placement involved bone contacts in 17% of children in the ultrasound group and 71% of children in the LOR group (P<0.0001). Epidurals were executed more swiftly in the ultrasound group [162 (75) s vs 234 (138) s; P<0.01]. Children under 6 months revealed a 0.9 correlation between skin-epidural depth and body weight. CONCLUSIONS: Ultrasonography is a useful aid to verify epidural placement of local anaesthetic agents and epidural catheters in children. Advantages include a reduction in bone contacts, faster epidural placement, direct visualization of neuraxial structures and the spread of local anaesthetic inside the epidural space. Ultrasound guidance requires additional training and good manual skills, and should only be used once experience in ultrasound-guided techniques of regional anaesthesia has been acquired.

Effect of newer anaesthetics on duration of stay in postanaesthesia care unit in patients undergoing major abdominal surgery.

Newer anaesthetic agents, such as remifentanil and sevoflurane, are more expensive than conventional anaesthetics, such as isoflurane and fentanyl. However, newer anaesthetics might outweigh their higher acquisition costs by reducing length of stay in the postanaesthesia care unit and thereby reducing personnel costs. We retrospectively investigated the influence of newer anaesthetics on time to eligibility for discharge from the postanaesthesia care unit in consecutive patients undergoing major abdominal surgery. Using a chart review, patients undergoing major abdominal surgery with three different anaesthetic regimens (isoflurane/fentanyl (n = 80), sevofluranelfentanyl (n = 40), and sevoflurane/remifentanil (n = 42)) were compared regarding duration of anaesthesia, surgery, time till extubation, and time to eligibility for discharge from the postanaesthesia care unit. Extubation times were shorter in patients in the sevoflurane/fentanyl and the sevoflurane/remifentanil groups compared to patients in the isoflurane/fentanyl group. Time to eligibility to discharge from the postanaesthesia care unit was similar in isoflurane/fentanyl and sevoflurane/fentanyl group. In the sevoflurane/fentanyl group, time to eligibility for discharge from the unit showed a tendency to be increased (P = 0.08), however these patients were significantly older compared to the other groups. Sevoflurane and remifentanil did not appear to reduce time to eligibility to discharge from the postanaesthesia care unit in our patients undergoing major abdominal surgery compared to isoflurane and fentanyl. This study highlighted the necessity for carefully planned transition from remifentanil to other longer-acting analgesia in our patients.

Ultrasonography for ilioinguinal/iliohypogastric nerve blocks in children.

BACKGROUND: The ilioinguinal/iliohypogastric nerve block is a popular regional anaesthetic technique for children undergoing inguinal surgery. The success rate is only 70-80% and complications may occur. A prospective randomized double-blinded study was designed to compare the use of ultrasonography with the conventional ilioinguinal/iliohypogastric nerve block technique. METHODS: One hundred children (age range, 1 month-8 years) scheduled for inguinal hernia repair, orchidopexy or hydrocele repair were included in the study. Following induction of general anaesthesia, the children received an ilioinguinal/iliohypogastric block performed either under ultrasound guidance using levobupivacaine 0.25% until both nerves were surrounded by the local anaesthetic or by the conventional 'fascial click' method using levobupivacaine 0.25% (0.3 ml kg(-1)). Additional intra- and postoperative analgesic requirements were recorded. RESULTS: Ultrasonographic visualization of the ilioinguinal/iliohypogastric nerves was possible in all cases. The amount of local anaesthetic used in the ultrasound group was significantly lower than in the 'fascial click' group (0.19 (SD 0.05) ml kg(-1) vs 0.3 ml kg(-1), P<0.0001). During the intraoperative period 4% of the children in the ultrasound group received additional analgesics compared with 26% in the fascial click group (P=0.004). Only three children (6%) in the ultrasound-guided group needed postoperative rectal acetaminophen compared with 20 children (40%) in the fascial click group (P<0.0001). CONCLUSIONS: Ultrasound-guided ilioinguinal/iliohypogastric nerve blocks can be achieved with significantly smaller volumes of local anaesthetics. The intra- and postoperative requirements for additional analgesia are significantly lower than with the conventional method.

Clonidine as an adjuvant to local anaesthetic axillary brachial plexus block: a randomized, controlled study.

BACKGROUND: We compared the effects of clonidine added to levobupivacaine and bupivacaine on axillary brachial plexus block as well as the effectiveness of levobupivacaine alone compared with bupivacaine alone. METHODS: In this prospective, randomized, controlled, double-blind trial, four groups of 20 patients each were investigated, using (i) 40 ml of levobupivacaine 0.5% plus 0.150 mg of clonidine, (ii) 40 ml of levobupivacaine 0.5% plus 1 ml of NaCl 0.9%, (iii) 40 ml of bupivacaine 0.5% plus 0.150 mg of clonidine, and (iv) 40 ml of bupivacaine 0.5% plus 1 ml of NaCl 0.9%, respectively. The onset of motor and sensory block and duration of sensory block were recorded. RESULTS: There was no significant difference in duration between groups, but a significantly higher variance (P<0.001) was found in the two groups with clonidine than in the two groups without. CONCLUSIONS: These findings suggest responder and non-responder behaviour is a result of the addition of clonidine.

Dixyrazine for the prevention of postoperative nausea and vomiting after laparoscopic cholecystectomy.

BACKGROUND: The study assessed the efficacy and safety of dixyrazine, an alternative neuroleptic drug to droperidol, in the prophylaxis of postoperative nausea and vomiting (PONV). METHODS: A total of 197 patients scheduled for laparoscopic cholecystectomy under general anesthesia were randomized to receive either dixyrazine 10 mg or placebo double-blinded at the end of surgery. Scores pertaining to PONV episodes, analgetic supply, rescue medication, adverse events and patient satisfaction were collected over the first 2 h in the PACU and the next 22 h in the ward. RESULTS: The incidence of PONV over the entire 24-h period was reduced from 32% in the placebo group to 13% in the dixyrazine group (P< or =0.004). The incidence of nausea in the first 2 h was reduced from 15% in the placebo group to 4% in the dixyrazine group (P< or =0.02) and from 12% to 5% in the next 22 h. The incidence of emetic episodes was not different between the two groups. Postoperative shivering was significantly less prevalent in the dixyrazine than in the placebo group (2% vs. 13%; P< or =0008), and opioid analgesics were required significantly less often (61% vs. 75%; P< or =0.01). No significant adverse effects were observed. Patient satisfaction was similar in both groups. CONCLUSION: Prophylactic dixyrazine is an effective, safe, and cheap antiemetic drug for laparoscopic cholecystectomy without involving any significant adverse events.

Ultrasound guidance for infraclavicular brachial plexus anaesthesia in children.

Ultrasonography may offer significant advantages in regional anaesthesia of the upper and lower limbs. It is not known if the same advantages demonstrated in adults also apply to children. We therefore performed a prospective, randomised study comparing ultrasound visualisation to conventional nerve stimulation for infraclavicular brachial plexus anasesthesia in children. Forty children scheduled for arm and forearm surgery underwent infraclavicular brachial plexus blocks with ropivacaine 0.5 ml.kg(-1) guided by either nerve stimulation or ultrasound visualisation. Evaluated parameters included sensory block quality, sensory block distribution and motor block. All surgical procedures were performed under brachial plexus anaesthesia alone. Direct ultrasound visualisation was successful in all cases and was associated with significant improvements when compared with the use of nerve stimulation: lower visual analogue scores during puncture (p = 0.03), shorter mean (median) sensory onset times (9 (5-15) min vs. 15 (5-25) min, p < 0.001), longer sensory block durations (384 (280-480) min vs. 310 (210-420) min, p < 0.001), and better sensory and motor block scores 10 min after block insertion. Ultrasound visualisation offers faster sensory and motor responses and a longer duration of sensory blockade than nerve stimulation in children undergoing infraclavicular brachial plexus blocks. In addition, the pain associated with nerve stimulation due to muscle contractions at the time of insertion is eliminated.

The effect of graded hypothermia (36 degrees C-32 degrees C) on hemostasis in anesthetized patients without surgical trauma.

UNLABELLED: The isolated effects of hypothermia on hemostasis have not been investigated in healthy humans. We cooled 16 anesthetized patients scheduled for elective intracranial surgery to 32 degrees C body core temperature and assessed prothrombin time (PT), activated partial thromboplastin time, thrombelastogram (TEG), closure time, and platelet count at 36 degrees C, 34 degrees C, and 32 degrees C body core temperature after the induction of anesthesia but before surgical intervention. Activated partial thromboplastin time, hematocrit, and closure time did not change, whereas PT and platelet count decreased during cooling. Platelet count decreased without a decrease in hematocrit; hence, a dilution by administered fluids seemed unlikely. The small decrease of platelet count is probably clinically irrelevant in patients with normal platelet count and function. The small decrease in PT indicates an alteration of the extrinsic pathway of coagulation. TEG measurements showed a delay of clot formation in temperature-adjusted measurements but showed no change if the test temperature was 37 degrees C. This indicates that hypothermia reduces plasmatic coagulation and platelet reactivity. However, the clot strength is not altered by hypothermia. All coagulation variables remained within the normal ranges. Our results may indicate that moderate short-term (4-h) hypothermia has only minor adverse effects in healthy humans. We can make no statement about the effects of hypothermia of longer duration. IMPLICATIONS: This study investigated the isolated effects of hypothermia in healthy anesthetized humans. We found only minor effects of body temperature reduction to 32 degrees C on assessed coagulation variables, indicating only minor effects in otherwise healthy humans.

Brachial plexus anaesthesia in children: lateral infraclavicular vs axillary approach.

BACKGROUND: Brachial plexus blockade is a well-established technique in upper-limb surgery. In paediatric patients, the axillary route is usually preferred to infraclavicular approaches because of safety considerations. Recent reports on a lateral infraclavicular approach offering greater safety in adults prompted us to perform a prospective randomized study to assess the analgesic efficacy of axillary vs lateral vertical infraclavicular brachial plexus (LVIBP) blocks in paediatric trauma surgery. METHODS: Forty paediatric trauma patients (ASA physical status I and II, age range 1-10 years) scheduled for forearm or hand surgery were randomly assigned to either axillary brachial plexus (ABP group) or LVIBP group blocks using 0.5 ml.kg(-1) ropivacaine 0.5%. Sensory blockade was evaluated by a visual analogue score and Vester-Andersen's criteria, the distribution of sensory and motor blockade was evaluated by a simplified pinprick test and motor tests. RESULTS: In the LVIBP group, Vester-Andersen's criteria were met by 100% of children, compared with 80% in the ABP group (P=0.035). Based on all assessable children, sensory blockade in the primary sensory regions of various nerves was significantly more effective in the LVIBP group (axillary: P < 0.0001; musculocutaneous: P=0.002; medial brachial cutaneous; P=0.008). Motor blockade was also significantly more effective (axillary: P < 0.0001; musculocutaneous: P=0.003). No major complications were observed in either group. DISCUSSION: We conclude that LVIBP blocks can be safely performed in children and that they add to the spectrum of sensory and motor blockade seen with the axillary approach.

Tromethamine buffer modifies the depressant effect of permissive hypercapnia on myocardial contractility in patients with acute respiratory distress syndrome.

In patients with acute respiratory distress syndrome (ARDS), permissive hypercapnia is a strategy to decrease airway pressures to prevent ventilator-induced lung damage by lowering tidal volumes and tolerating higher arterial carbon dioxide tension. However, in experimental studies hypercapnia impairs myocardial contractility and hemodynamic function. We investigated the effect of short-term permissive hypercapnia on myocardial contractility and hemodynamics in patients with ARDS. We hypothesized that the administration of tromethamine (THAM), a buffer which does not increase carbon dioxide production, would modify these changes. In 12 patients with ARDS, permissive hypercapnia was implemented for 2 h with a target Pa(CO(2))of 80 mm Hg. Patients were randomized to have respiratory acidosis corrected by THAM (pH-corrected group), or not corrected (pH-uncorrected group). Hemodynamic responses were measured, and transesophageal echocardiography (TEE) was used to determine myocardial contractility. Permissive hypercapnia resulted in significant decreases in systemic vascular resistance (SVR) and increases in cardiac output (Q). Myocardial contractility decreased in both groups but significantly less in the pH-corrected group (approximately 10%) than in the pH-uncorrected group (approximately 18%, p < 0.05). Mean arterial pressure decreased and mean pulmonary arterial pressure increased significantly only in the pH-uncorrected group. All values returned to baseline conditions 1 h after permissive hypercapnia was terminated. Our study demonstrates a reversible depression of myocardial contractility and hemodynamic alterations during rapid permissive hypercapnia which were attenuated by buffering with THAM. This may have applicability to the clinical strategy of permissive hypercapnia and allow the benefit of decreased airway pressures to be realized while minimizing the adverse hemodynamic effects of hypercapnic acidosis.

Magnetic resonance imaging of the distribution of local anesthetic during the three-in-one block.

UNLABELLED: The three-in-one technique of simultaneously blocking the femoral, the lateral femoral cutaneous (LFC), and the obturator nerves by a single injection of a local anesthetic was first described in 1973, and it was suggested that the underlying mechanism was one of cephalad spread resulting in a blockade of the lumbar plexus. Today, the technique is widely used in surgery and pain management of the lower limb. Many investigators have, however, reported suboptimal analgesia levels, particularly in the obturator nerve. The purpose of this prospective study was to trace the distribution of a local anesthetic during a three-in-one block by means of magnetic resonance imaging (MRI). Seven patients scheduled for surgery of the lower limb were analyzed with the aid of a primary MRI and then received three-in-one blocks using 30 mL of bupivacaine 0.5% under the guidance of a nerve stimulator. A secondary MRI was performed to determine the distribution pattern of the local anesthetic. It emerged that the local anesthetic blocks the femoral nerve directly, the LFC nerve through lateral spread, and the anterior branch of the obturator nerve by slightly spreading in a medial direction. No involvement of the proximal and posterior portions of the obturator nerve was observed, nor was there any cephalad spread that could have resulted in a lumbar plexus blockade. We therefore conclude that the basis of the three-in-one block is confined to lateral, medial, and caudal spread of the local anesthetic, which effectively blocks the femoral and LFC nerves, as well as the distal anterior branch of the obturator nerve. IMPLICATIONS: We demonstrate by using magnetic resonance imaging that the mechanism of a three-in-one block is one of lateral, caudal, and slight medial spread of a local anesthetic with subsequent blockade of the femoral, the lateral femoral cutaneous, and the anterior branch of the obturator nerves. It does not involve cephalad spread of the local anesthetic with blockade of the lumbar plexus.

Three-in-one blocks with ropivacaine: evaluation of sensory onset time and quality of sensory block.

UNLABELLED: The purpose of this prospective, randomized, double-blinded study was to evaluate the sensory onset time and the quality of sensory block of ropivacaine, a new long-acting local anesthetic, compared with bupivacaine, for 3-in-1 blocks. Fifty ASA physical status I-III patients undergoing hip surgery after trauma were randomly assigned to two study groups of 25 patients each. The two study groups received a 3-in-1 block with either 20 mL of ropivacaine 0.5% or 20 mL of bupivacaine 0.5%. Blocks in both groups were performed using a nerve stimulator. The sensory onset time and the quality of sensory block was assessed by pinprick test in the central sensory region of each of the three nerves and compared with the same stimulation in the contralateral leg. We used a scale from 100% (normal sensation) to 0% (no sensory sensation). We did not find significant differences in sensory onset times between the ropivacaine group and the bupivacaine group (30+/-11 vs 32+/-10 min). The quality of sensory blocks was also comparable between the study groups (19%+/-20% vs 21%+/-15%). We conclude that the sensory onset time and quality of sensory block during 3-in-1 blocks performed with ropivacaine are comparable to those with bupivacaine. Ropivacaine is described as being less potent than bupivacaine, making this local anesthetic promising for 3-in-1 blocks because of its reportedly lower incidence of cardiovascular and central nervous system complications. IMPLICATIONS: Ropivacaine 0.5% has a sensory onset time and quality of sensory block during 3-in-1 blocks similar to that of bupivacaine 0.5%. Ropivacaine is described as being less potent than bupivacaine, making it a promising local anesthetic for 3-in-1 blocks because of its reportedly lower cardiovascular and central nervous system toxicity.

The arterial to end-tidal carbon dioxide gradient increases with uncorrected but not with temperature-corrected PaCO2 determination during mild to moderate hypothermia.

UNLABELLED: End-tidal carbon dioxide (PETCO2) monitoring is recommended as a basic standard of care and is helpful in adjusting mechanical ventilation. Gas solubility changes with temperature, which might affect the PaCO2 and thereby the gradient between PaCO2 and PETCO2 (PA-ETCO2) under hypothermic conditions. We investigated whether the PA-ETCO2 changes during mild to moderate hypothermia (36 degrees C-32 degrees C) using PaCO2 measured at 37 degrees C (uncorrected PaCO2) and PaCO2 corrected to actual body temperature. We preoperatively investigated 19 patients. After anesthesia had been induced, controlled ventilation was established to maintain normocarbia using constant uncorrected PaCO2 to adjust ventilation (alpha-stat acid-base regimen). Body core temperature was reduced without surgical intervention to 32 degrees C by surface cooling. Continuous PETCO2 was monitored with a mainstream PETCO2 module. The PA-ETCO2 was calculated using the uncorrected and corrected PaCO2 values. During body temperature reduction from 36 degrees C to 32 degrees C, the gradient between PETCO2 and uncorrected PaCO2 increased 2.5-fold, from 4.1 +/- 3.7 to 10.4 +/- 3.8 mm Hg (P < 0.002). The PA-ETCO2 remained unchanged when the corrected PaCO2 was used for the calculation. We conclude that when the alpha-stat acid-base regimen is used to adjust ventilation, the PA-ETCO2 calculated with the uncorrected PaCO2 increases and should be added to the differential diagnosis of widened PA-ETCO2. In contrast, when the corrected PaCO2 is used for the calculation of the PA-ETCO2, the PA-ETCO2 remains unaltered during hypothermia. IMPLICATIONS: We investigated the impact of induced hypothermia (36 degrees C-32 degrees C) on the gradient between PaCO2 and PETCO2 (PA-ETCO2). The PA-ETCO2 increased 2.5-fold when CO2 determinations were not temperature-corrected. Hypothermia should be added to the differential diagnosis of an increased PA-ETCO2 when the alpha-stat acid-base regimen is used.

Endogenous heparin-like substances significantly impair coagulation in patients undergoing orthotopic liver transplantation.

UNLABELLED: Orthotopic liver transplantation (OLT) is associated with severe bleeding, especially after reperfusion of the grafted liver. Heparin released from the liver graft contributes to postreperfusion coagulopathy. Although patients with liver cirrhosis have increased levels of endogenous heparinoids, the role of these substances during liver transplantation is unclear. Therefore, we performed native and heparinase-modified thrombelastography (TEG) in 72 patients undergoing OLT. TEG was performed at skin incision, 10 min before and 10 min after clamping of the vena cava, 10 min before and 10 min after graft perfusion, and at the end of surgery. Heparinase-modified TEG compared with native TEG demonstrated heparin activity. In contrast to other investigations, we found significant heparin effects before reperfusion, although patients received no exogenous heparin. These heparin effects were greater in patients with cirrhosis compared with patients with cancer as the underlying disease leading to OLT. Administration of coagulation factors is the usual treatment of coagulopathies during OLT. The comparison of native versus heparinase-modified TEG can distinguish between heparin activity or coagulation factor deficiency as a cause of bleeding complications and provides a rational approach to the treatment of bleeding during OLT. IMPLICATIONS: Impaired coagulation function, contributed to by heparin or heparin-like substances, is frequently observed after reperfusion of a transplanted liver. This study demonstrates that a heparinase-modified thrombelastography can identify significant heparin effects in the absence of exogenous heparin administration in patients undergoing liver transplantation.

[5 years neuroblastoma screening in Austria: rate of participation, results and a comparison with other screening areas]. / Fünf Jahre Neuroblastom-Screening in Osterreich: Beteiligungsrate, Ergebnisse und ein Vergleich mit anderen Screeningregionen.

In late 1990 a screening program for the early detection of neuroblastoma in infants was introduced in Austria. The program is performed on a voluntary basis in collaboration with general pediatricians and practitioners. Filter strips for urine collection are distributed to parents of infants aged seven to nine months on the occasion of a routine check up. The samples are sent to the laboratory by parents and analysed for vanillylmandelic acid (VMA) and homovanillic acid (HVA). Between January 1991 and December 1995 125,201 infants were screened. The compliance rate was 26.8% for Austria, but great differences were seen for different regions (65% in Carinthia, 10% in Vorarlberg). 30 children were admitted to hospital for investigation of repeatedly elevated urine catecholamines. A neuroblastoma was identified in 16 cases. In 12 of these cases at least one unfavorable prognostic factor was present (stage > or = 3, elevated LDH, unfavorable histology, N-myc amplification, di- or tetraploidy). Neuroblastoma screening of infants aged more than six months seems to detect predominantly those tumors which are unlikely to regress spontaneously. The observation of one false negative case, however, demonstrates that neuroblastomas which become clinically manifest at a later date may remain undetected by early screening. Possible advantages of shifting screening to a later age and repeated screening are discussed.