S(+)-ketamine for rectal premedication in children

Our purpose for this prospective, randomized, and double-blinded study was to evaluate the anesthetic efficacy of S(+)-ketamine, an enantiomer of racemic ketamine, compared with a combination of S(+)-ketamine and midazolam, and plain midazolam for rectal premedication in pediatric anesthesia. Sixty-two children, ASA physical status I and II, scheduled for minor surgery, were randomly assigned to be given rectally one of the following: 1.5 mg/kg preservative-free S(+)-ketamine, a combination of 0.75 mg/kg preservative-free S(+)-ketamine and 0.75 mg/kg midazolam, or 0.75 mg/kg midazolam. Preoperative anesthetic efficacy was graded during a period of 20 min by using a five-point scale from 1 = awake to 5 = asleep. Tolerance during anesthesia induction via face mask was graded by using a four-point scale from 1 = very good to 4 = bad. A sufficient anesthetic level (> or = 3) after rectal premedication was reached in 86% in midazolam/S(+)-ketamine premedicated children, in 75% in midazolam premedicated children, but only in 30% in S(+)-ketamine premedicated children (P < 0.05 S(+)-ketamine versus midazolam/S(+)-ketamine and midazolam groups). The incidence of side effects after rectal premedication was rare. Whereas the mask acceptance score was comparable in the three study groups, a 25% rate of complications during anesthesia induction via face was observed in the S(+)-ketamine study group (P < 0.05 versus other study groups). Our conclusions are that S(+)-ketamine for rectal premedication in the dose we chose shows a poor anesthetic effect and a frequent incidence of side effects during induction of anesthesia via face mask compared with the combination of midazolam/S(+)-ketamine and plain midazolam. Dose-response studies of S(+)-ketamine for rectal premedication in pediatric anesthesia may be warranted.

Analgesic effects of caudal and intramuscular S(+)-ketamine in children

BACKGROUND

Previous studies suggest that caudal administration of ketamine cause effective analgesia. The purpose of the current study was to compare the clinical effectiveness and plasma concentrations of S(+)-ketamine after caudal or intramuscular administration in children to distinguish between local and systemic analgesia.

METHODS

After induction of general anesthesia, 42 patients, aged 1 to 7 yr, scheduled to undergo inguinal hernia repair randomly received a caudal (caudal group) or intramuscular (intramuscular group) injection of 1 mg/kg S(+)-ketamine. Intraoperatively, heart rate (HR), mean arterial pressure (MAP) and arterial oxygen saturation were measured. Postoperative measurements included duration of analgesia, a four-point sedation score, and hemodynamic and respiratory monitoring for 6 h in the recovery room. Analgesic requirements in the recovery room were assessed by an independent blinded observer using an observational pain/discomfort scale (OPS). Plasma samples for determination of ketamine concentrations were obtained before and 10, 20, 30, 45, 60, 90, 120, and 180 min after injection of S(+)-ketamine.

RESULTS

A significantly longer duration of analgesia (P < 0.001) was observed after caudal administration (528 min [220-1,440 min]; median [range]) when compared with intramuscular administration (108 min [62-1,440 min]) of S(+)-ketamine. Plasma levels of ketamine were significantly lower from 10 to 45 min after caudal administration than after intramuscular injection.

CONCLUSION

Caudal S(+)-ketamine provides good intra- and postoperative analgesia in children. Despite similar plasma concentrations during most of the postoperative observation period, caudal S(+)-ketamine provided more effective analgesia than did intramuscular S(+)-ketamine, indicating a local analgesic effect.

[Orthostasis in halothane anesthesia. A model situation for studying cerebrovascular autoregulation in infants]

Halothane causes impairment of cerebrovascular reactivity and autoregulation. We used transcranial Doppler sonography (TCD) to investigate the reaction patterns of cerebral blood flow velocities (CBFV) during a standardized orthostatic maneuver after premedication and during halothane anesthesia in infants. After premedication orthostasis led to no significant changes in CBFV. During halothane anesthesia CBFV was significantly higher than after premedication, and orthostasis induced a significant decrease in CBFV compared to values obtained in horizontal position. Heart rate and mean blood pressure were significantly lower than before medication during halothane anesthesia. The observed changes in CBFV during halothane anesthesia represent a characteristic pattern of impaired cerebral autoregulation. The changes in CBFV and heart rate demonstrate that neither systemic nor cerebral hemodynamics compensate for hydrostatic inducement during halothane anesthesia. The tilting test is a useful tool for determining cerebral autoregulation capacity in infants.

Traumatic pharyngo-oesophageal perforation in the newborn: a condition mimicking oesophageal atresia

Two newborn infants with traumatic perforation of the pharyngo-oesophageal region are presented. This injury was induced by pharyngeal suction catheters and/or vigorous attempts at nasogastric or tracheal intubation during resuscitation of the newborn. The true nature of this condition remained unrecognized and the babies were thus referred with a tentative diagnosis of oesophageal atresia. The perforation itself could be treated successfully without surgery, despite a severe complication in one infant resulting from inadvertent use of barium sulphate contrast medium. Raising awareness of the possibility of this injury should help in avoiding this complication by gentle and skilful action during newborn resuscitation, particularly in the premature infant.

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.

IMPLICATIONS

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.

S(+)-ketamine for caudal block in paediatric anaesthesia

We have evaluated the intra- and postoperative analgesic efficacy of preservative-free S(+)-ketamine compared with bupivacaine for caudal block in paediatric hernia repair. After induction of general anaesthesia, 49 children undergoing hernia repair were given a caudal injection (0.75 ml kg-1) of S(+)-ketamine 0.5 mg kg-1 (group K1), S(+)-ketamine 1.0 mg kg-1 (group K2) or 0.25% bupivacaine with epinephrine 1:200,000 (group B). No additional analgesic drugs were required during operation in any of the groups. Haemodynamic and respiratory variables remained stable during the observation period. Mean duration of analgesia was significantly longer in groups B and K2 compared with group K1 (300 (SD 96) min and 273 (123) min vs 203 (117) min; P < 0.05). Groups B and K2 required less analgesics in the postoperative period compared with group K1 (30% and 33% vs 72%; P < 0.05). Postoperative sedation scores were comparable between the three groups. We conclude that S(+)-ketamine 1.0 mg kg-1 for caudal block in children produced surgical and postoperative analgesia equivalent to that of bupivacaine.

Incidence and therapy of midazolam induced hiccups in paediatric anaesthesia

A prospective, randomized and double blind study was undertaken to determine the incidence and a possible dose- or age-dependence of hiccups in children premedicated with rectal midazolam and to investigate the treatment of hiccups by intranasal ethyl chloride spray application. Two hundred ASA physical status 1 and 2 children, weighing 3.0 to 15.0 kg, scheduled for minor surgery, were randomly assigned to be given either 0.5 mg.kg-1 midazolam(n=100) or 1.0 mg. kg-1 midazolam (n=100) administered rectally. If hiccups were observed during a period of 20 min after premedication with midazolam, these children were treated after 3 min of hiccups with two short intranasal applications of ethyl chloride spray. Hiccups occurred in 22% of children in the 0.5 mg.kg-1 group and 26% in the 1.0 mg.kg-1 group (n.s.). The intranasal application with ethyl chloride was successful in 100% in both groups. The mean age levels between children with or without hiccups were 5+/-9 months vs 21+/-19 months (P<0.01) in the 0.5 mg.kg-1 group and 6+/-7 months vs 20+/-14 months (P<0.01) in the 1.0 mg.kg-1 group. Intranasal application of ethyl chloride spray seems to be an effective therapy for midazolam induced hiccups in paediatric anaesthesia. The incidence of these hiccups is highly age significant, but not dose dependent.

The dose-response of caudal ropivacaine in children

BACKGROUND

Ropivacaine, a new local anesthetic, is less cardiotoxic in adults and is less likely to cause motor blockade than is bupivacaine. The authors evaluated the clinical effectiveness and hemodynamic effects of ropivacaine compared with bupivacaine and the pharmacokinetics of ropivacaine when given for caudal blocks in 56 children 4.1 +/- 1.2 yr old (mean +/- SD).

METHODS

Patients scheduled for inguinal hernia repair were randomly given a caudal injection (0.75 ml/kg) of ropivacaine, 0.25% (R0.25 group); ropivacaine, 0.5% (R0.5 group); or bupivacaine, 0.25% (B0.25 group). Postoperative measurements included the duration of analgesia, which was our primary outcome variable, and hemodynamic and respiratory monitoring for 4 h in the recovery room. Thereafter, analgesic requirements for the following 24 h were assessed by an independent observer on the ward using an observational pain-discomfort scale, which gives a cumulative score from 5 to 15 to estimate the quality of analgesia by assessment of behavioral objective parameters. Plasma levels of ropivacaine were measured before the procedure was started and 5, 10, 15, 20, 25, 30, and 45 min and 1, 2, 4, 6, 8, and 24 h after caudal block.

RESULTS

A significantly longer (P < 0.0001) duration of analgesia (median [range]) was observed in the R0.5 group (1,440 [335-1,440] min), whereas the R0.25 group (208 [175-340] min) and the B0.25 group (220 [100-390] min) were comparable. All groups showed a significant decrease in mean arterial blood pressure and heart rate from baseline values, but differences between groups were not observed.

CONCLUSION

Ropivacaine is well tolerated and provides effective analgesia when given for caudal blockade in small children for inguinal hernia repair.

Simulation of an epidural test dose with intravenous isoproterenol in sevoflurane- and halothane-anesthetized children

Isoproterenol has been suggested as an alternative marker for epidural test dosing in children receiving halothane anesthesia. The purpose of this prospective, randomized, double-blind study was to determine the chronotropic response to IV isoproterenol in sevoflurane-anesthetized children. Thirty-six ASA physical status I children (0.5-8 yr) were anesthetized with either halothane or sevoflurane at 1 minimum alveolar anesthetic concentration adjusted for age in 70% nitrous oxide. Patients received incremental IV injections of isoproterenol until their heart rate increased > or = 20 bpm above baseline. The minimal effective dose of isoproterenol required to produce an increase of > or = 20 bpm was 55 ng/kg (42-72 ng/kg; 95% confidence interval) in sevoflurane-anesthetized children and 32 ng/kg (26-38 ng/kg; 95% confidence interval) in halothane-anesthetized children (P < 0.05). This dose-response study suggests that sevoflurane antagonizes beta-adrenergic-mediated chronotropic responses to isoproterenol more than halothane. These observations also suggest that larger doses of isoproterenol will be necessary for epidural test dosing in children receiving sevoflurane rather than halothane anesthesia.

IMPLICATIONS

Isoproterenol has been suggested as an alternative marker for epidural test dosing in children receiving halothane anesthesia. This isoproterenol dose-response study indicates that larger doses of isoproterenol will be necessary for epidural test dosing in children undergoing sevoflurane rather than halothane anesthesia.

Sevoflurane anaesthesia in paediatric patients: better than halothane?

Forty-two children (aged 2-16 years) were randomly assigned to receive either sevoflurane (n = 21) or halothane (n = 21) in nitrous oxide/oxygen. After pre-medication with midazolam, anaesthesia was induced by facemask and the anaesthetic concentration was increased until loss of eyelash reflex (sevoflurane, 6%; halothane, 2.5%). Thereafter, 1-1.5 MAC of the inhalational agents were maintained until skin closure. Intra-operative analgesia was provided either by intermittent intravenous (i.v.) bolus doses of fentanyl (2-3 micrograms kg-1) or by a regional blockade. Induction was smooth and the time to loss of eyelash reflex was slightly shorter with sevoflurane than with halothane, the difference not quite reaching statistical significance (P = 0.06). In both groups, heart rate remained stable and blood pressure decreased significantly during induction. Haemodynamic parameters remained stable during anaesthetic maintenance; no cardiac dysrhythmias were observed. Emergence time with sevoflurane was 12.9 min vs. 16.3 min with halothane, but this difference was not statistically significant. It is concluded that sevoflurane is as suitable for paediatric patients as halothane. The slightly faster emergence time offered by sevoflurane over halothane was of no clinical significance in the present study.

The efficacy and safety of a clonidine/bupivacaine combination in caudal blockade for pediatric hernia repair

We evaluated the analgesic efficacy and hemodynamic and respiratory safety of clonidine when added to bupivacaine for caudal blocks in 58 children aged 38 +/- 2 mo (mean +/- SEM). Patients scheduled for ambulatory hernia repair were randomly given a caudal injection (0.75 mL/kg) of either saline placebo (P group), bupivacaine, 0.25% (B group), bupivacaine plus epinephrine 1:200,000 (BE group), bupivacaine plus clonidine 1 microgram/kg (BC1 group), or bupivacaine plus clonidine 2 micrograms/kg (BC2 group). Postoperative measurements included duration of analgesia, hemodynamics, and respiratory monitoring for 6 h. Thereafter, parents assessed their child's analgesic requirements at home every 3 h for 18 h. The duration of analgesia (median [range]) was significantly longer (P < 0.05) in the BC1 and BC2 groups (360 [270-360] min and 360 [355-360] min, respectively) compared with the P (77[45-190]), B (346[105-360]), or BE group (300[75-360]). Similarly, the BC1 and BC2 groups required less additional analgesic within the first 24 h. All groups showed a significant decrease in mean arterial pressure compared with baseline values, but the differences among the groups were not significant. Bradycardia and respiratory depression were not observed. Clonidine 1 and 2 micrograms/kg can be safely added to bupivacaine caudal blockade in small children for ambulatory hernia repair to achieve an increased duration of analgesia compared with bupivacaine alone or bupivacaine plus epinephrine.

IMPLICATIONS

The addition of clonidine, an antihypertensive drug with analgesic properties, to local anesthetics in caudal blocks prolongs postoperative pain relief and reduces the need for additional pain treatment in children after hernia operation.

Sevoflurane in paediatric anaesthesia

Sevoflurane is a potent inhalational agent, combining several advantages of specific interest in paediatric anaesthesia. Rapid and smooth induction, a safe cardiovascular profile, rapid emergence and a short postoperative recovery with minimal side effects are ideal characteristics of this agent for the use in paediatric anaesthesiology. The apparent improvement in management should not obscure the fact that sevoflurane in higher MAC should be used with caution in renal impairment. For the future world of our children, the lack of chlorine in the structure makes sevoflurane theoretically less ozone-depleting than halothane and isoflurane, a substance contributing to environmental protection.

Sedation and anaesthesia outside the OR

The sedation of paediatric patients is associated with serious risks such as hypoventilation, apnoea, airway obstruction, and cardiopulmonary impairment; these risks should be avoided or accurately and rapidly diagnosed and appropriately treated. Appropriate management may include ventilation by mask and cardiopulmonary resuscitation, which require special training and skills.

The efficacy and safety of a clonidine/bupivacaine combination in caudal blockade for pediatric hernia repair

We evaluated the analgesic efficacy and hemodynamic and respiratory safety of clonidine when added to bupivacaine for caudal blocks in 58 children aged 38 +/- 2 mo (mean +/- SEM). Patients scheduled for ambulatory hernia repair were randomly given a caudal injection (0.75 mL/kg) of either saline placebo (P group), bupivacaine, 0.25% (B group), bupivacaine plus epinephrine 1:200,000 (BE group), bupivacaine plus clonidine 1 microgram/kg (BC1 group), or bupivacaine plus clonidine 2 micrograms/kg (BC2 group). Postoperative measurements included duration of analgesia, hemodynamics, and respiratory monitoring for 6 h. Thereafter, parents assessed their child's analgesic requirements at home every 3 h for 18 h. The duration of analgesia (median [range]) was significantly longer (P < 0.05) in the BC1 and BC2 groups (360 [270-360] min and 360 [355-360] min, respectively) compared with the P (77[45-190]), B (346[105-360]), or BE group (300[75-360]). Similarly, the BC1 and BC2 groups required less additional analgesic within the first 24 h. All groups showed a significant decrease in mean arterial pressure compared with baseline values, but the differences among the groups were not significant. Bradycardia and respiratory depression were not observed. Clonidine 1 and 2 micrograms/kg can be safely added to bupivacaine caudal blockade in small children for ambulatory hernia repair to achieve an increased duration of analgesia compared with bupivacaine alone or bupivacaine plus epinephrine.

IMPLICATIONS

The addition of clonidine, an antihypertensive drug with analgesic properties, to local anesthetics in caudal blocks prolongs postoperative pain relief and reduces the need for additional pain treatment in children after hernia operation.

Lack of nonshivering thermogenesis in infants anesthetized with fentanyl and propofol

BACKGROUND

Sweating, vasoconstriction, and shivering have been observed during general anesthesia. Among these, vasoconstriction is especially important because-once triggered-it minimizes further hypothermia. Surprisingly, the core-temperature plateau associated with vasoconstriction appears to preserve core temperature better in infants and children than adults. This observation suggests that vasoconstriction in anesthetized infants may be accompanied by hypermetabolism. Consistent with this theory, unanesthetized infants rely on nonshivering thermogenesis to double heat production when vasoconstriction alone is insufficient. Accordingly, the authors tested the hypothesis that intraoperative core hypothermia triggers nonshivering thermogenesis in infants.

METHODS

With Ethics Committee approval and written parental consent, the authors studied six infants undergoing abdominal surgery. All were aged 1 day to 9 months and weighed 2.4-9 kg. Anesthesia was maintained with propofol and fentanyl. The infants were mechanically ventilated and allowed to cool passively until core (distal esophageal) temperatures reached 34-34.5 degrees C. Oxygen consumption-the authors' index of metabolic rate-was recorded throughout cooling. Because nonshivering thermogenesis triples circulating norepinephrine concentrations, arterial blood was analyzed for plasma catecholamines at approximately 0.5 degree C intervals. Thermoregulatory vasoconstriction was evaluated using forearm-fingertip, skin-surface gradients, with gradients exceeding 4 degrees C, indicating intense vasoconstriction. The patients were subsequently rapidly rewarmed to 37 degrees C. Regression analysis was used to correlate changes in oxygen consumption and plasma catecholamine concentrations with core temperature.

RESULTS

All patients were vasoconstricted by the time core temperature reached 36 degrees C. Further reduction in core temperature to 34-34.5 degrees C did not increase oxygen consumption. Instead, oxygen consumption decreased linearly. Hypothermia also failed to increase plasma catecholamine concentrations.

CONCLUSIONS

Even at core temperatures approximately 2 degrees C below the vasoconstriction threshold, there was no evidence of nonshivering thermogenesis. This finding is surprising because all other major thermoregulatory responses have been detected during anesthesia. Infants and children thus appear similar to adults in being unable to increase metabolic rate in response to mild intraoperative hypothermia.

Simulation of an epidural test dose with intravenous isoproterenol in awake and in halothane-anesthetized children

BACKGROUND

An epidural test dose containing epinephrine does not reliably produce hemodynamic responses in children under halothane anesthesia. The purpose of this study was to determine hemodynamic responses to intravenous isoproterenol in both awake and halothane-anesthetized children.

METHODS

After obtaining institutional review board approval and parental informed consent, 72 ASA physical status 1 or 2 children (2.8 +/- 1.7 yr) undergoing elective minor surgery were studied before and during anesthesia with 1.2 minimum alveolar concentration halothane. A bolus containing 0.25 mg/ kg bupivacaine and 0.05 microgram/kg, 0.075 microgram/kg, or 0.1 microgram/kg isoproterenol, or bupivacaine and saline was injected via a peripheral arm vein to simulate intravascular injection of an epidural test dose.

RESULTS

Before induction of anesthesia, all patients showed a positive test response after isoproterenol injection (heart rate increase > or = 20 beats/min). During anesthesia, 79% of patients receiving 0.05 microgram/kg, 89% of patients receiving 0.075 microgram/kg, and 100% of patients receiving 0.1 microgram/kg met the criterion of a positive test response. Among each treatment group, all infants showed a positive test response. Blood pressure did not differ among the groups at any time. Transient benign dysrhythmias occurred in only one patient under halothane anesthesia receiving 0.075 microgram/kg isoproterenol.

CONCLUSION

Isoproterenol at a dose of 0.1 microgram/kg is a sensitive indicator for intravascular injection of a test dose in children anesthetized with halothane and nitrous oxide. Isoproterenol at a dose of 0.05 microgram/kg approximates a minimal effective dose in awake children and in infants. After detailed studies on neural toxicity, isoproterenol could be of value as an epidural test agent in children.

Effective pain relief with continuous intrapleural bupivacaine after thoracotomy in infants and children

The effect of continuous intrapleural bupivacaine on pain relief after lateral thoracotomy was studied in nine infants (< or = 15 kg body weight) and 11 children (> 15 kg body weight). An intrapleural catheter was inserted under direct vision during surgery. After extubation, the patients were transferred to the ICU where vital signs and pain scores were monitored. An intrapleural infusion of bupivacaine 0.25% with adrenaline was given at a loading dose of 0.625 mg.kg-1 body weight followed by a continuous infusion with a starting rate of 1.25 mg.kg-1.h-1. Haemodynamic and respiratory parameters did not differ significantly from control values throughout the study period in either group. The mean infusion rate could be reduced stepwise in both groups to 0.75 +/- 0.32 mg.kg-1.h-1 and 0.73 +/- 0.38 mg.kg-1.h-1 respectively. The pain score indicated a rapid onset of analgesia in both groups and remained low during the study period. The degree of analgesia amongst other factors was position dependent. The lack of any recognizable side effects or complications related to this method has been most encouraging. Only one child required a supplementary dose of an opioid. We conclude that continuous intrapleural access has proved to be a safe and suitable route for pain relief in infants and children following thoracotomy.

Effects of dobutamine versus insulin on cardiac performance, myocardial oxygen demand, and total body metabolism after coronary artery bypass grafting

OBJECTIVE

The purpose was to study whether the hemodynamic benefit of a catabolic catecholamine (dobutamine) induces a certain oxygen cost for the myocardial energy demand and whether this effect would be less pronounced if an anabolic intervention, such as the administration of insulin, was used.

DESIGN

A prospective and randomized study.

SETTING

A university hospital.

PARTICIPANTS

Investigation of two comparable groups of cardiac patients.

INTERVENTIONS

The interventions were postoperative infusions of dobutamine, 7 micrograms/kg/min, and of insulin, 1.5 U/kg/h, respectively, over a period of 30 minutes.

MEASUREMENTS AND MAIN RESULTS

The effects of the interventions were measured using parameters relating to cardiac work and myocardial oxygen demand. Moreover, parameters relating to total body metabolism were also recorded. In the dobutamine group, cardiac index (CI) and left ventricular stroke work index (LVSWI) increased significantly (p < 0.05) during therapy by 30% and 40%, respectively. Cardiac effort index (CEI) and tension time index (TTI) also increased (p < 0.05) during therapy by 41% and 30%, respectively. However, in the insulin group, CI and LVSWI also increased (p < 0.01 and p < 0.05) during therapy, although to a lesser extent (16% and 14%), but CEI and TTI did not change at all during therapy. Total body CO2 production (VCO2) and O2 consumption (VO2) in the dobutamine group increased (p < 0.05) during therapy by 9% and 11%, respectively, whereas in the insulin group only CO2 production increased (p < 0.05) by 13%. O2 consumption remained unchanged in this group.

CONCLUSIONS

It is concluded that dobutamine as well as insulin administration increase cardiac performance. However, in contrast to dobutamine, insulin does not appear to increase myocardial oxygen demand. Therefore, the anabolic insulin administration may represent a more economic pattern of energy-consuming hemodynamic intervention than does the catabolic catecholamine administration.

Resistance of nitrogen metabolism to growth hormone treatment in the early phase after injury of patients with multiple injuries

OBJECTIVES AND DESIGN

Several studies have shown an anticatabolic effect of recombinant human growth hormone (rhGH) in surgical patients. We investigated, in a prospective, randomized, double blind, and placebo-controlled study, the effect of r-hGH on hormone and nitrogen metabolism in 14 patients with multiple injuries in the early phase of injury.

MATERIALS AND METHODS

All patients were treated in the intensive care unit, had mechanical ventilation, and were highly catabolic, with a mean daily nitrogen loss of 13.2 +/- 1.8 g. r-hGH was given subcutaneously (once a day, at 8 PM) in a dosage of 0.2 IU/kg.d for seven days, starting on the second day after injury.

RESULTS

Administration of r-hGH evoked a significant increase in plasma concentrations of GH, insulin-like growth factor-I (IGF-I), and insulin-like growth factor binding-protein-3 (IGFBP-3). No significant differences were found for either daily or cumulative nitrogen balances (-103.1 +/- 14 g for patients receiving r-hGH and -92.1 +/- 18.1 for those with placebo). r-hGH therapy did not affect skeletal muscle extracellular water, nor did it affect plasma or muscle concentrations of total free amino acids or glutamine. Plasma albumin, prealbumin, and retinol-binding protein concentrations were also unchanged by r-hGH therapy, as were the urinary excretion of potassium and urea.

CONCLUSIONS

We conclude that elevated plasma levels of GH, insulin, and IGF-I are unable to effect a protein anabolic drive in patients with multiple injuries during the early postinjury phase and assume that this r-hGH resistance to nitrogen metabolism takes place at the level distal to IGF-I.

[Regional anesthetic procedures in pediatric anesthesia]

Regional anaesthetic procedures are not popular in paediatric anaesthesia in many institutions. However, regional anaesthesia is gaining ground, especially in a "new" concept of balanced paediatric anaesthesia. The decisive argument for the use of regional anaesthesia is the prolongation of pain relief further into the postoperative phase. The minimal haemodynamic and respiratory side effects during epidural and spinal anaesthesia, the reduced narcotic requirement and the potential early mobilisation all speak in favour of practical application of these techniques. Specially adapted needles and catheters have reduced the technical limitations. The use of nerve stimulators has optimize the accuracy of needle and catheter positioning. The use of a nerve stimulator is therefore highly recommended for peripheral nerve blocks in children. On the other hand, the use of regional anaesthesia in children has potential disadvantages, which should be considered. Special knowledge and continuous training are required. Many techniques are time consuming and personnel intensive, at least temporarily, and the combination of general and regional anesthesia exposes the child to the potential risk inherent in both procedures. The aim of this paper is to discuss procedures which have gained favour in paediatric regional anaesthesia during the past few years. These include caudal, epidural and spinal anaesthesia, especially for infants with high narcotic risk, as well as fascia iliaca compartment blocks for lower extremity analgesia and penile blocks. Many peripheral nerve blocks require special experience and therefore are not discussed here, but they are used routinely by specialists in all age groups. Good anatomic and pharmacologic knowledge should be a prerequisite for all physicians who use regional anaesthetic procedures. Continuous training and critical analysis are needed for good results. Only then can such methods be introduced into routine paediatric anaesthetic practice.

[Continuous application of morphine is more effective than a bolus administration in the postoperative analgesia and sedation of children]

In ventilated children the cardiorespiratory and metabolic reserve capacities can be extremely limited. Therefore, these children have low thresholds of tolerance for additional stress factors. One of the most obvious aims in the critical postoperative period after heart surgery in children is protection of the cardiorespiratory system against stress reactions. Pain and restlessness are such stress factors. The aim of this study was to identify the most effective form for the application of opiates for analgesia and sedation. The randomized study was performed in 12 ventilated normothermic children after intracardiac surgery. No child was catecholamine-dependent. The biometric and clinical data are shown in Table 1. After stabilization of cardiorespiratory functions in the early postoperative period, the effects on VO2 of morphine hydrochloride, infused continuously (group I, 0.5-1.0 microgram/kg per min), and morphine administered as bolus injections on demand (group II, 0.05 mg/kg) were compared. The mean arterial blood pressure, heart rate, body temperatures and blood gases were measured during a 6-h period in the postoperative intensive care unit. During this time VO2 measurements were done continuously with the DELTATRAC Metabolic Monitor 100 (Datex). Mean values were calculated hourly (T1-T7). In addition, a scoring system according to recently published data was used hourly. Mean values and standard deviations (SD) were calculated and comparisons were carried out with paired two-tailed t-tests. Probability values below 0.05 were considered to indicate statistical significance. The study was accepted by the ethical committee. The score used for postoperative pain showed no difference between the two treated groups. Nevertheless, in the course of VO2, shown in Fig. 1, a difference between groups was detected. During the first hour of the investigation, VO2 increased in both groups. Thereafter, VO2 was significantly lower under continuous morphine application than under bolus injections. VO2 decreased slowly under both regimes but remained significantly lower under continuous application. Continuous application of morphine was more effective in sparing VO2 than bolus injections in ventilated children after cardiac surgery. We conclude that continuous application of morphine represents stress prevention whereas bolus application of morphine is stress therapy. From the clinical point of view it is more effective to prevent than to treat pain and other stress factors in pediatric patients.

[Indirect calorimetry in mechanically ventilated children. 3. Clinical use of a new measurement procedure]

After the new device for measurement of oxygen uptake (VO2) and carbon dioxide elimination (VCO2) was tested in a pneumatic lung model, we investigated its clinical practicability. First the level of VO2 and VCO2 in the early postoperative phase was determined. Secondly we examined alterations in gasexchange caused by various intensive care activities. Whereby main concern was the change from mechanical ventilation to spontaneous CPAP-breathing. Ten children undergoing cardiac surgery (age: 10 days to 10 years) were included in the study. Three children were primarily investigated on the CPAP-system. Data from another six were collected under controlled ventilation as well as under spontaneous CPAP-breathing. One child had to be ventilated for a longer time (greater than 24 h). The change from mechanical ventilation to spontaneous breathing was accompanied with a temporary increase of VO2 and VCO2. As expected, all stressful factors like tracheal suction, pain or anxiety increased these two variables. Also some drugs showed remarkable changes. While marked increases under Normastigmine, Naloxone, and Dopamine could be observed, gas exchange was decreased under Morphine. However, heart rate showed no good correlation with VO2. We conclude that the developed prototype is a reliable device for measuring VO2 and VCO2. Our results suggest that spontaneous CPAP-breathing is not always accompanied with increased gas exchange. If there is an increased gas exchange, it may refer to transient changes during the adaption phase. Therefore, a continuous monitoring of VO2 and VCO2 over a longer period of time is necessary. Consequently the first phase after changing ventilatory support has to be viewed carefully. The heart rate in children, undergone cardiac surgery, is not a good predictor for determination of VO2 and thus for energy expenditure. This device allows to quantify accurately oxygen consumption and carbon dioxide elimination in ventilated children. Furthermore, alterations in metabolism and cardiopulmonary variables caused by intensive care and therapeutic interventions can be examined continuously. It seems to be a valuable tool for metabolic and cardiopulmonary monitoring in critically ill children.

[Indirect calorimetry in artificially respirated children. 2. A measuring procedure and its evaluation in a newly developed metabolism-lung model]

A new device for continuous measuring oxygen uptake (VO2) and carbondioxide elimination (VCO2) in artificially ventilated or CPAP-system breathing children has been developed. A dual-channel analyzer system based on zirconiumoxyd cells measures oxygen fractions. This allows not only single measurements but also continuous determination of fraction differences for oxygen (delta FO2) (accuracy +/- 0.003 Vol%). Carbondioxide is measured by infrared absorption. A mixing device for inspiratory gas was designed to smooth fluctuations of inspired oxygen fractions almost completely. The reliable sampling system for expiratory gases has already been described [19]. The breathing-e.g. ventilating-system was modified in such a way that the total gas flow is independent of mode and breathing volume (equally 15 l/min). For which purpose we use a self aspirating, time-cycled, volume limited respirator or a high-flow-CPAP-system. The prototype described ran test performances on a specially developed pneumatic metabolic-lung-model. This new lung model enables free choice of respiratory quotient (R) by independent setting of O2-uptake and CO2-elimination. Under these controlled laboratory conditions gasvolume-balances correspond to expected values in children really as shown during simulated trials. In the metabolic-lung-model accuracy and reproduction averaged +/- 1% for VCO2. Both were independent of the mode of ventilatory support, FIO2, and R. Determinations of VO2 were more dependent on FIO2 and R. After computing primary data according to a special formula which equalizes differences between VI and VE the maximal error was +/- 7%. Maximum difference between preset and measured R-values ranging from 0.769 to 1.429 was -4.6%, determined at R = 1.429. By means of this independent test series insights into clinically expected measurement errors and dimensions of limits of accuracy could be demonstrated. It seems to be justified that our newly developed device for accurate measuring O2-uptake and CO2-elimination is highly recommendable for use in extremely difficult conditions as in ventilated children.

[Uptake and elimination of isoflurane and halothane by children and adults]

The rate of increase of alveolar concentrations (FA/FI) of isoflurane and halothane was studied in children and adults during general anaesthesia and controlled ventilation. After 30 min of body equilibrium, elimination curves of the volatile anaesthetics were determined by measurement of alveolar (FA/FA0; infrared technique) and venous concentrations (gas chromatography). The distribution and elimination half-times (t1/2 alpha, t1/2 beta), clearance (Cl), volume of central and peripheral compartment (V1, Vz) and the volume of distribution at steady state (Vss) were calculated from the intercepts and slopes of a two-compartment model. During the uptake of anaesthetic concentrations of isoflurane and halothane, the FA/FI ratio of each gas was found to rise significantly faster in children than in adults. The reason for the more rapid approach to equilibrium in children seems to be related to physiological differences. Irrespective of age, uptake of isoflurane was more rapid than that of halothane, as it is less soluble. Similarly, isoflurane was eliminated from the lung or blood faster than halothane. Moreover, anaesthetic wash-out in children differed from that in adults. In the paediatric age group t1/2 beta under isoflurane was shorter than in adults, whereas halothane excretion took longer in children. This could be accounted for by the larger volumes of distribution Vz and Vss in the young, due to higher organ affinity of halothane. From our data we conclude that age significantly affects uptake and elimination of volatile anaesthetics and the control of anaesthesia is easiest with isoflurane in paediatric patients.

[Indirect calorimetry in the artificially respirated polytraumatized patient. I. Studies in adults]

Significant changes in oxygen uptake (VO2) and carbon dioxide output (VCO2) as well as resting energy expenditure (RMR) can be observed in critically ill patients. Reliable data, although needed by the clinician especially in long term ventilated patients, have not been obtainable so far. We developed a modular system which provides by means of mass-spectrometry, accurate reproducible results. Furthermore, the design of the gas sampling module minimalizes systemical failures in the expiratory branch. Two groups of polytraumatized patients (n = 10, n = 7 respectively) with different amounts of intravenous amino-acid support and identical energy supply were included in the study. During the first week all patients showed significantly elevated values for VO2 and VCO2 with a tendancy to increase. High amino-acid supply resulted in higher rate of gas exchange and disproportional increase in energy expenditure. Subsequently reduced carbohydrate intake was found to be effective in reduction of gas exchange earliest after 24 h. Oxidation rates for glucose and fat did not correspond to energy supply ratio of substrates. It can be stated that in polytraumatized patients amino-acid supply more than 75 g/24 h/m2 is not economical in terms of energy gains and is therefore not generally recommended. Reduction of carbohydrates in the weaning period of respirator in these patients is likely to be effective only in borderline cases and started early before weaning (greater than 24 h). Energy supply by means of carbohydrates should exceed the energy derived from fat supply in the nutritional regime according to oxidation rates in polytraumatized patients.

[Nitrogen metabolism and renal amino acid excretion during total parenteral feeding of hypermetabolic patients with various carbohydrate regimes]

During an investigative study about the utilization of parenterally administered amino-acids (AA) in severe catabolic states nitrogen balances, urea production rates and catabolic nitrogen as well as urinary losses of amino-acids were determined in six adult polytraumatized patients treated in an intensive care unit. In addition to 19 g nitrogen (0.3 g N/kg/day) 3,000 kcal (12.5 MJ) were given simultaneously as carbohydrates. Either a mixture of laevulose 20%, glucose 10%, xylitol 10% (LGX) or glucose 50% were infused alternatively for four days in a randomized cross-over scheme. Another group of three patients received the LGX-regime alone for six days altogether. Higher urinary N-losses, increased urea production rates corresponding to a rise in the s.c. catabolic nitrogen were obtained on days where the LGX-mixture was infused; there was also an increased excretion of alpha-amino-N due to a distinct aminoaciduria. Not all amino-acids did react in the same manner. When comparing excretion to supply higher losses (greater than 20%) were observed for: THR greater than TRY greater than VAL greater than ILE greater than PHE. Methionine and alanine were also excreted in higher amounts, whereas under glucose an elevated excretion was especially noted with glutamine and alpha-aminobutyric acid. The increased urea production rate associated with a reduced incorporation of amino-acids as well as the accentuated renal AA-losses under LGX may be ascribed to a slight increase in protein catabolism connected with some impairment of AA-utilization due to a temporary metabolic hepatic 'block'. Under glucose an intensified endogenous mobilization as well as the higher exogenous supply of insulin might be responsible for a somewhat better AA-utilization. Amino-acid clearances under the carbohydrate mixture in the second group were - with the exception of lysine and leucine - raised distinctly similar to values seen in aminoaciduria of other origin. This leads to the assumption that the AA-overflow might result from a partial insufficiency or overload of renal transport ('carrier') systems being responsible for amino-acid reabsorption. The question of an adequate supply - concerning essential amino acids in particular - taking into consideration the relatively high losses under one of the nutritional regimes investigated is shortly touched upon. Finally the possibility of adapting AA-mixtures to the respective carbohydrate solutions in order to improve nitrogen balances and utilization is discussed.

[Pharmacokinetics and pharmacodynamics of vecuronium in children]

Pharmacodynamics of vecuronium have been studied in children 1 to 10 years old. Doses from 0.015 to 0.1 mg/kg were given and the effects measured mechanically and by electromyography. For 0.1 mg/kg the pharmacokinetics were established. A smaller distribution volume and higher plasma clearance in children as compared to adults have been found, while the dose-effect ratio is the same. The action of vecuronium is shorter in children than in adults.

[A thermodynamic model to predict oxygen consumption and peripheral blood flow in the newborn infant. II. Its validity under steady-state conditions]

A thermodynamic model, which allows to predict oxygen consumption and peripheral blood flow from temperature measurements, was tested for its validity in newborn infants. This model is based on the close relation between 1) oxygen consumption and heat production and 2) between circulation and heat convection. In this model 3 temperatures on the patient, 2 temperatures in the environment and geometrical variables (weight, length) are measured and known physiological relations used to calculate oxygen consumption (VO2) and peripheral blood flow (pBF). In 15 newborns the VO2 was synchroneously determined by means of the flow-trough method and the thermomodel. The VO2 and the VO2/kg bodyweight respectively correlated significantly (p less than 0.01) with the directly measured VO2 (correlation coefficients r 0.89 and 0.66 respectively). In 12 newborns the peripheral blood flow was synchroneously determined by means of the impedance plethysmography and the thermomodel. The directly measured peripheral blood flow correlated significantly (p less than 0.001) with the peripheral heat flow (r = 0.73, 34 measurements) and with the peripheral blood flow (r = 0.86, 34 measurements) both obtained from the thermomodel. The values of VO2 and pBF obtained by direct measurement and by the thermomodel are as closely correlated as values which were obtained comparing two conventional methods. These results demonstrate the validity of the theoretical model being suitable for clinical use to continuously predict VO2 and pBF.

Relative roles of heart rate and ventricular stroke volume for the regulation of cardiac output during controlled hypotension with sodium nitroprusside in man

The effects of N-allyl clonidine (St 567, alinidine), (0.5 mg/kg i.v.) a substance with specific bradycardic action at the sinus node, were studied on a total of thirteen patients in neuroleptanaesthesia and during controlled hypotension with sodium nitroprusside (SNP). Invariably, the fall in blood pressure was associated with an increase in heart rate (20.0 +/- 4.3+; P less than 0.01), presumably due to an activation of the arterial baroreceptor reflex. Alinidine decreased heart rate to the original level but no fall in cardiac output occurred a ventricular stroke volume and the calculated left ventricular stroke work were increased compensatorily (35.9 +/- 7.2% and 35.9 +/- 6.7%, P less than 0.01, respectively). In patients who received alinidine before the onset of controlled hypotension (n = 5) SNP failed to elicit an increase in heart rate. It is concluded that in patients under neuroleptanaesthesia tachycardiac does not play an important role for the maintenance of an adequate cardiac output during controlled hypotension with SNP.

[Metabolism during shock and its therapeutic regulations]

During shock the organism reacts by means of primarily useful autoregulation mechanisms which, however, in excess become useless and at least harmful. Therapeutically it is necessary now, to partly break through these mechanisms going along with substitution of certain necessary substances and besides that in part to support the organism's own concept.

[Metabolic studies on intensive care patients during gastric tube feeding with a formulated diet, rich in bulk]

Results of metabolic investigations in 5 intensive care patients fed via gastric tube with a prefabricated formula diet (based on milk protein, rich in bulk material) are reported. Clinical handling proved to be rather simple, due to the homogeneity of the mixture tube, obstruction never occurred. Tolerance of the tested tube feeding was good in 4 of 5 patients (in 1 tetanus patient the study to be interrupted because of acute abdominal symptoms), mean body weight increased. During the 10-day treatment period, a slightly positive nitrogen balance (mean 1.4 +/- 5.9 g/day) resulted in a cumulative nitrogen retention of 15.5 g. Fat losses in faeces, probably due to high intake (more than 50% of calories administered), were moderately elevated compared to normal values; in some patients decreased fat resorption with steatorrhoea was observed on various days. The formula diet under investigation may be qualified as a suitable nutritional regime for intensive care patients with intact gastrointestinal function. In cases with impaired fat utilization, however, relative calorie deficiency interfering with protein synthesis (gluconeogenesis) might occur. Lowering of the fat quota (having been taken into account in the meantime) to the benefit of elevated carbohydrates may be desirable in this context.

[Observations on the course of leucocytes in cardiac surgery under acupuncture-analgesia (author's transl)]

In 11 cardiosurgical patients leucocyte and differential counts were made performed during and after surgery. In some cases Lymphocyte transformation and migration inhibitiontest was studied. Comparing cases under conventional neurolept anaesthesia with those who had acupuncture Analgesia (electrostimulation) it appeared that the number of leucocytes was rising significantly higher in the latter, although the total number of lymphocytes remained constant. In lymphocyte transformation and mirgration inhibitiontest the observed decrease seemed to be less pronounced. Because a trial applying acupuncture in healthy persons resulted in no change in the number of leucocytes, it is suggested that the surgical trauma and related catecholamine release might be of importance. No definite result could be obtained.

[Clinical and experimental results with acupuncture-analgesia (author's transl)]

Operations under acupuncture analgesia have been performed in Vienna since March 1972. A total of 102 procedures has been performed with "classical" Chinese acupuncture analgesia. Additionally given analgesics, psychodynamic factors and neurophysiological components are of joint importance. Our success rate in these cases was 64 p.c. Since October 1972 we call "two-phase-acupuncture-analgesia". Up to June 1975 72 operations were performed under some modifications of this method. In a neurophysiological study 17 volunteers and in 2 patients undergoing stereothalamotomies depression or even disappearance of evoked potentials was be observed during acupuncture with alectrical stimulation. Thus an interaction between pain stimuli and acupuncture stimuli in the thalamus could for the first time be demonstrated in man.