Postoperative pain assessment in children: a pilot study of the usefulness of the analgesia nociception index

BACKGROUND

The ability to perform objective pain assessment is very important in paediatric patients. The goal of this study was to investigate the relationship between the analgesia nociception index (ANI), which is based on the heart rate variability, and objective measurements of pain intensity in young or cognitively impaired children, after surgical or imaging procedures (control group) under general anaesthesia.

METHODS

On arrival in the recovery room and subsequently at 5-10 min intervals, the level of pain was rated using the FLACC pain scale (0-10). The ANI values (0-100; 0 indicating the worst pain) were recorded simultaneously. The area under the receiver operating characteristic curve (AUC) and grey zone approach were used to evaluate the performance of the ANI to detect patients with FLACC >4. Instantaneous ANI values were compared with ANI values averaged over 256 s periods of time.

RESULTS

All children in the surgical group (n=32) developed moderate-to-severe pain (FLACC >4). Children in the control group (n=30) exhibited minimal pain. Instantaneous ANI values were lower in children of the surgical group than in the control group [52 (sd16) vs 69 (16), P<0.001]. The AUC for the 256 s ANI recording period [0.94 (95% confidence interval 0.85-0.99)] was significantly higher than for instantaneous ANI (P<0.05). When measured for a period of 256 s, an ANI cut-off value of 56 (grey zone [58-60]) was most predictive of a FLACC ≥4.

CONCLUSIONS

The ANI may provide an objective measurement of acute postoperative pain, which is correlated with that measured on a FLACC scale in young or cognitively impaired children.

Audit of protocols for treatment of paediatric burns in emergency departments in the Île de France

INTRODUCTION

The main purpose of this study was to establish the existence and accuracy of protocols for treatment of children with burns in emergency departments (EDs) across the Île de France. In addition, we also analysed the incidence of paediatric burns.

METHODS

A postal questionnaire was sent to 91 EDs in the Île de France. Data collected were: number of children with burns in 2005, the absence or presence of specific written protocols. The ED was asked to send a copy of the protocol for analysis.

RESULTS

Forty-six EDs (50.5%) replied to the questionnaire. These EDs treated a total of 3258 children with burns, corresponding to 0.63% of paediatric pathologies in EDs. Amongst responding EDs, 48% had specific written protocols for the management of children with burns (but only in the larger EDs: >10000 patient visits/year). A written protocol for managing pain in children was present in 65% of cases. For analgesia, 80% used oxygen/nitrous oxide. Concerning second-step analgesics, six EDs 67% used a combination of paracetamol/codeine and only 22% used non-steroidal antiflammatory drug. Regarding third-step analgesics, 67% used nalbuphine while only 43% used morphine.

CONCLUSION

3,200 children were registered with burns in half of the region's EDs during 2005 (0.63% of paediatric consultations). The larger the ED the higher was the availability of specific written protocols. International recommendations appeared to be respected concerning dressings, management of pain being marked by an under-utilisation of morphine.

Remifentanil infusion for cleft palate surgery in young infants

BACKGROUND

The residual depressant effect of opioid is a major concern in infants scheduled for cleft palate repair. Remifentanil is associated with a fast and predictable recovery, independent of age.

METHODS

About 40 infants in the 2-12 month age range were prospectively enrolled in this open study, to receive either remifentanil (infusion starting at 0.25 microg x kg(-1) x min(-1)) or sufentanil as part of a balanced anaesthesia regimen. Isoflurane was maintained at an endtidal concentration of 1.2% in oxygen and nitrous oxide and the opioid dosing was titrated to autonomic responses. Postoperative pain relief was provided by morphine infusion. Morphine administration started intraoperatively in the remifentanil group.

RESULTS

Consistent haemodynamic stability was achieved throughout surgery in both groups. Infants of the remifentanil group required, on average, lower concentrations of isoflurane than children of the sufentanil group (1.2 +/- 0.2% vs 1.7 +/- 0.3%, P < 0.001). The median time from last suture to tracheal extubation was 12.5 min (5-25 min) in the remifentanil group and 15.0 min (10-30 min) in the sufentanil group. There was no evidence of hyperalgesia or enhanced morphine consumption in the remifentanil group compared with the sufentanil group. Postoperative pain scores were even lower in the remifentanil group, compared with the sufentanil group, soon after arrival in the postanaesthesia care unit.

CONCLUSIONS

Remifentanil-based anaesthesia appeared well suited for primary cleft palate repair in young infants.

Adverse events of premixed nitrous oxide and oxygen for procedural sedation in children

In France, administration of premixed 50% nitrous oxide and oxygen for procedural sedation is under close supervision by the French Drug Agency before final approval for use. We have examined the frequency of adverse events in children sedated with 50% nitrous oxide and oxygen over a broad range of non-specialised facilities. A mean of 0.33% (SD 0.10) children had major adverse events. Thus, premixed 50% nitrous oxide and oxygen seems to be a safe option for procedural sedation in children.

Analgesic effect of low-dose intrathecal morphine after spinal fusion in children

BACKGROUND

This study was designed to assess the postoperative analgesic effect of low-dose intrathecal morphine after scoliosis surgery in children.

METHODS

Thirty children, 9-19 yr of age, scheduled for spinal fusion, were randomly allocated into three groups to receive a single dose of 0 (saline injection), 2, or 5 microg/kg intrathecal morphine. After surgery, a patient-controlled analgesia device (PCA) provided free access to additional intravenous morphine. Children were monitored for 24 h in the postanesthesia care unit.

RESULTS

The three groups were similar for age, weight, duration of surgery, and time to extubation. The time to first PCA demand was dose-dependently delayed by intrathecal morphine. The first 24 h of PCA morphine consumption was 49 +/- 17, 19 +/- 10, and 12 +/- 12 mg (mean +/- SD) in the saline, 2 microg/kg morphine, and 5 microg/kg morphine groups, respectively. Pain scores at rest were significantly lower over the whole study period after 2 and 5 microg/kg intrathecal morphine than after saline, but there was no difference between intrathecal doses. Pain scores while coughing and the incidence of side effects were similar in the three groups.

CONCLUSIONS

These data demonstrate that low-dose intrathecal morphine supplemented by PCA morphine provides better analgesia than PCA morphine alone after spinal fusion in children. The doses of 2 and 5 microg/kg seem to have similar effectiveness and side-effect profiles, whereas a reduction of intraoperative bleeding was observed in patients who received 5 microg/kg but not 2 microg/kg intrathecal morphine.

Sedation and analgesia for procedures outside the operating room in children

There has been a dramatic increase in the number of procedures that are conducted in children in which sedation is now considered beneficial. In many institutions, however, resources and personnel have not been recruited to address this increase in demand. In most institutions, anaesthesiology departments are not able to provide anaesthesia for all procedures that are performed outside the operating theatre, and alternative solutions are needed. Recent research includes attempts to decrease the time required to induce sedation and to recover from it, and development of new organizational models to improve the safety of procedural sedation.

[Spermatic cord torsion in the newborn: role of surgical exploration]

Torsion of the spermatic cord is frequent in neonates suffering from acute scrotal distress. A retrospective study was carried out to determine the viability and the outcome of testis treated by surgical exploration.

PATIENTS AND RESULTS

Surgical exploration of 30 neonates presenting acute scrotal distress found: 18 torsions of the spermatic cord, six intrascrotal bleedings or hematoma due to delivery trauma, five tunica vaginalis inflammations and one ischemia without torsion. The torsion occurred in utero in 16 cases and after birth in two cases. The contralateral uninvolved testis was fixed to the scrotum in all cases. The torsion was extravaginal in 17 cases and intravaginal in one case. In all cases of prenatal torsion, there was total necrosis of the testis. One case of postnatal torsion operated on four hours after the beginning of the torsion was saved.

CONCLUSION

Although the viability of the torsioned testis is compromised in cases of prenatal torsion, surgical exploration is necessary to confirm diagnosis and to avoid any contralateral torsion because bilateral torsion exists. Only emergency surgical exploration can save a testis that has undergone post-natal torsion as reported in others series.

Spatial encoding properties of subnucleus reticularis dorsalis neurons in the rat medulla

The effect of spatial summation, produced by noxious thermal stimuli, was investigated on medullary Subnucleus Reticularis Dorsalis (SRD) neurons of anaesthetized rats. Neurons with 'whole body' receptive fields were excited by a random sequence of thermal stimuli involving four different surface areas of a hindpaw (1.9, 4.8, 7.5 and 18 cm(2)). The responses of SRD neurons progressively decrease when the area of noxious stimulation exceeded 4.8 cm(2). The shape of the stimulus-response curve closely match the shape of dorsal horn convergent neurons, previously recorded under similar experimental conditions. These results suggest that, with respect to spatial encoding properties, SRD neurons are driven by the same supraspinally-mediated inhibitory mechanisms as dorsal horn convergent neurons.

Fixed 50% nitrous oxide oxygen mixture for painful procedures: A French survey

OBJECTIVE

Although the equimolecular mixture of oxygen and nitrous oxide (EMONO) seems a good choice to relieve procedure-related pain in children, it has not been accepted everywhere. In France, the rapid spread of its use has elicited suspicion and doubts regarding its safety. To assess the use and the safety of this gas mixture in the pediatric settings in France, we conducted a national survey.

METHODOLOGY

Centers that had accepted a nation- wide invitation to participate in the survey filled out a questionnaire after each EMONO administration during a 2-month study. Procedure and inhalation characteristics, as well as pain evaluations and side effects, were reported.

RESULTS

One thousand nineteen EMONO inhalations from 31 centers that agreed to participate in this 2-month survey were analyzed. Median (range) age was 6.4 (0-18) years. Four percent (46) of children were 12 months old or younger, 29% (295) were 5 years old or younger, 45% (459) were 6 to 10 years old, and 26% (265) were older than 10 years of age. The procedures performed with EMONO inhalation were: lumbar punctures (286), bone marrow aspirations (BMA; 231), laceration repairs (215), minor procedures (75), minor surgery (53), punctures (49), fractures (45), dental care (43), and pulmonary endoscopy (22). Nine percent of procedures were undertaken without the presence of a physician; the child being observed only by the attending nurse. A drug association was noted in 182 (17.9%) of procedures: midazolam (63%), acetaminophen (18%), nalbuphine (8.5%), hydroxyzine (5%), flunitrazepam (2%), chlorazepate (2%), morphine (1%), and lorazepam (.5%). EMLA cream (Astra) was applied in 98.6% of lumbar punctures, 93.7% of BMA, and 54.2% of punctures including lymph nodes, hematoma, or renal biopsies. Lidocaine infiltration was performed in 51% of minor surgery procedures, 40% of laceration repairs, and 28% of BMA. The inhalation system included a whistle, a scented mask, and a nonrebreathing respiratory valve in 48.9%, 71.2%, and 78.3% of the patients, respectively. Initial physical restraint was needed in 18. 2% of all the patients. Inhalation refusal was noted in 129 (12.7%) children; of these, 53 had an alternative method of analgesia (EMLA or lidocaine infiltration), 15 had no other analgesia, and in the remaining 61, EMONO inhalation was maintained against the child's will. Median (interquartile) inhalation length was 4 (3-5) minutes before starting the procedure and 6 (6-15) minutes for the total inhalation. Median (interquartile) procedural pain evaluations were 9 (0-30) for children on a 0 to 100 visual analog scale, 1 (0-3) for both nurses and parents on a 0 to 10 numerical scale. Median (interquartile) procedural pain as evaluated by nurses for the 3 most frequent procedures were 0 (0-2) for lumbar punctures, 2 (0-4) for bone marrow aspiration, and 2 (0-4) for laceration repair. Comparison of pain assessed by nurses in children 3 years old or younger and those older than 3 years of age showed a median (range) score of 2 (0-10) versus 1 (0-10), respectively. Pain self-assessment was completed in 647 children 6 years of age or older. Median (interquartile) children pain assessments were as follows: lumbar puncture (5; 0-20), bone marrow aspiration (12.5; 0-40), laceration repair (12; 0-40), minor procedures (18; 0-32), minor surgery (10; 0-35), punctures (0; 0-18), fracture (15; 0-30), dental care (20; 0-40), and pulmonary endoscopy (15; 0-30). Ninety-three percent of the 647 children who were able to answer the question said they would accept EMONO analgesia if a new procedure were to be performed. Behavioral reactions during procedures varied with age of the child; cry was observed in 44.1%, 24.4%, 12.9%, and 11.2% of children 3 years or younger, 4 to 6 years, 7 to 10 years, and 11 years or older, respectively. Physical restraint was necessary in 34.2%, 22%, 13.5%, and 8.4% of children aged 3 years or younger, 4 to 6 years, 7 to 10 years, and 11 years or old

Laparoscopic diagnosis of contralateral patent processus vaginalis in children under 1 year of age with unilateral inguinal hernia: comparison with herniography

PURPOSE

The effectiveness of laparoscopic diagnosis of contralateral patent processus vaginalis (CPPV) in children with unilateral inguinal hernia was evaluated.

METHODS

Ninety-three consecutive children under the age of 1 year were operated on for a unilateral inguinal hernia. A contralateral CPPV was diagnosed by laparoscopy via the inguinal hernia sac before ligation. The laparoscopy results of this technique were correlated with those of herniography or inguinal exploration.

RESULTS

Laparoscopy was performed on 88 patients; sensitivity was 71% and specificity 89%. The only complication arising from the procedure was wound infection in two patients.

CONCLUSION

This method is a simple, safe, and accurate procedure for selecting children for contralateral surgical exploration.

Relative effectiveness of lignocaine-prilocaine emulsion and nitrous oxide inhalation for routine preoperative laboratory testing

We studied the impact of age-related factors and the benefits of 50% nitrous oxide or EMLA cream in 108 children undergoing preoperative laboratory testing. Procedural pain was assessed by behavioural scores (CHEOPS) and pain intensity ratings. Age, preexisting behavioural distress and difficulty of venous access were significant predictors of outcome in univariate analysis. Nitrous oxide and EMLA cream were both effective in lowering pain related behaviour and pain ratings generated by the different adult observers and the children where applicable. EMLA cream was more effective than 50% nitrous oxide in children 1-4 years old. Although EMLA cream was responsible for a 28+/-5 min prolongation of waiting time at the clinic, the present results suggest that it should remain the first line intervention to alleviate pain from venepuncture in paediatric outpatients.

Effect of systemic morphine on the responses of convergent neurons to noxious heat stimuli applied over graded surface areas

BACKGROUND

Stimulus intensity is a major determinant of the antinociceptive activity of opiates. This study focused on the influence of the spatial characteristics of nociceptive stimuli, on opiate-induced depressions of nociceptive transmission at the level of the spinal cord.

METHODS

Anesthetized rats were prepared to allow extracellular recordings to be made from convergent neurons in the lumbar dorsal horn. The effects of systemic morphine (1 and 10 mg/kg) were compared with those of saline for thermal stimuli of constant intensity, applied to the area of skin surrounding the excitatory receptive field (1.9 cm2) or to a much larger adjacent area (18 cm2).

RESULTS

The responses (mean +/- SD) elicited by the 1.9-cm2 stimulus were not modified by 1 mg/kg intravenous morphine, although they were decreased by the 10-mg/kg dose (to 11+/-4% of control values compared with saline; P < 0.05). In contrast, when the 18-cm2 stimulus was applied, 1 mg/kg intravenous morphine produced a paradoxical facilitation of the neuronal responses (159+/-36% of control values; P < 0.05) and 10 mg/kg intravenous morphine resulted in a weaker depression of the responses (to 42+/-24% of control values; P < 0.05) than was observed with the smaller stimulus.

CONCLUSIONS

Doses of systemic morphine in the analgesic range for rats had dual effects on nociceptive transmission at the level of the spinal cord, depending on the surface area that was stimulated. Such effects are difficult to explain in terms of accepted pharmacodynamic concepts and may reflect an opioid-induced depression of descending inhibitory influences triggered by spatial summation.

[Does a means exist for prevention of postoperative pain?]

Postoperative pain can be prevented through pharmacological and non pharmacological means. The influence of the interval between therapy and surgical stimulus, which corresponds to "pre-emptive analgesia" in English-speaking countries (comparison of preoperative administration with pre- and postoperative administration of the same analgesic) has been assessed by numerous studies of good methodological quality. In spite of the initial promising results, most of the results published at present are negative. In an enlarged concept of postoperative pain prevention, various trials have demonstrated the benefits of the choice of the surgical approach, as well as the psychological preparation of the patient for surgery.

[Intravenous iron in the treatment of postoperative anemia in surgery of the spine in infants and adolescents]

PURPOSE OF THE STUDY

Spinal fusion surgery often leeds to massive bleeding responsible for anemia in the postoperative period. The aim of this study was to compare the effect of IV iron III hydroxide sucrose complex (Venofer) versus oral iron fumarate administration in postoperative anemia. The efficacy of both treatments was evaluated by comparing hemoglobin level in the postoperative period.

METHODS

Two groups of sixteen patients, scheduled for anterior and/or posterior spinal fusion, were compared. Group 1, historical, was treated by supplementation of 10 mg/kg/day oral iron fumarate. Administration was started when hemoglobin level fell below 9 g/100 ml. Group 2 was treated by intravenous iron sucrose complex using same criteria as in group 1 for starting administration. The dosage of iron was individually adapted according to a target hemoglobin level of 13 g/100 ml and to the actual lowest hemoglobin level measured. The total iron deficit was calculated with the following formula: total iron deficit (mg) = 0.24 x body weight (kg) x (target Hb-actual Hb)(g/l). The patients were supplemented by 3 mg/kg/day until the calculated iron deficit was compensated.

RESULTS

Both groups were identical regarding age and lowest hemoglobin level reached in the postoperative period. Hemoglobin increased by 0.25 g/day in group 1, and by 0.36 g/day in group 2. In others words, the beneficial effect of IV iron versus oral iron administration was as high as 45 per cent (p = 0.003).

CONCLUSION

Intravenous iron therapy as ferric sucrose complex is a new and more effective form of iron therapy than oral iron therapy to restore postoperative hemoglobin after spinal surgery in children.

Addition of clonidine or fentanyl to local anaesthetics prolongs the duration of surgical analgesia after single shot caudal block in children

Caudal anaesthesia is indicated for surgical procedures lasting less than 90 min. Fentanyl and clonidine are known to prolong postoperative caudal analgesia, but there are no data on their effect on duration of surgical analgesia. We evaluated if the addition of clonidine or fentanyl to local anaesthetics prolonged the duration of surgical analgesia after single shot caudal block in children in a randomized, double-blind study. We studied 64 children, aged 6-108 months, undergoing bilateral correction of vesicoureteral reflux which was expected to last more than 90 min. Patients were allocated to one of four groups: group O received 1 ml kg-1 of a mixture of 0.25% bupivacaine with epinephrine and 1% lidocaine in equal parts; group F received the same mixture of local anaesthetics in addition to fentanyl 1 microgram kg-1; group C received the same mixture of local anaesthetics in addition to clonidine 1.5 micrograms kg-1; and group C + F received the same mixture of local anaesthetics in addition to fentanyl 0.5 microgram kg-1 and clonidine 0.75 microgram kg-1. Single shot caudal block was sufficient in only 57% of children in group O compared with 93% in groups C and F and 86% in group C + F (P = 0.035). Global assessment of anaesthesia, defined as the time from caudal injection to the first administration of analgesic (either during or after surgery), was significantly longer in the three groups of children who received additives compared with local anaesthetics alone (P = 0.035), but there were no differences between the three additive groups. Vomiting was observed only in children who received fentanyl. Addition of clonidine or fentanyl to local anaesthetics prolonged the duration of surgical analgesia of caudal block, allowing single shot caudal anaesthesia to be recommended for surgery lasting 90-150 minutes. Clonidine had some advantages over fentanyl as it did not produce clinically significant side effects.

Involvement of the caudal medulla in negative feedback mechanisms triggered by spatial summation of nociceptive inputs

In the rat, applying noxious heat stimuli to the excitatory receptive fields and simultaneously to adjacent, much larger, areas of the body results in a surface-related reduction in the responses of lumbar dorsal horn convergent neurons. These inhibitory effects induced by spatial summation of nociceptive inputs have been shown to involve a supraspinally mediated negative feedback loop. The aim of the present study was to determine the anatomic level of integration of these controls and hence to ascertain what relationships they might share with other descending controls modulating the transmission of nociceptive signals. The responses of lumbar convergent neurons to noxious stimulation (15-s immersion in a 48 degrees C water bath) applied to increasing areas of the ipsilateral hindlimb were examined in several anesthetized preparations: sham-operated rats, rats with acute transections performed at various levels of the brain stem, and spinal rats. The effects of heterotopic noxious heat stimulation (tail immersion in a 52 degrees C water bath) on the C-fiber responses of these neurons also were analyzed. The electrophysiological properties of dorsal horn convergent neurons, including their responses to increasing stimulus surface areas, were not different in sham-operated animals and in animals the brain stems of which had been transected completely rostral to a plane -2. 8 mm remote from interaural line (200 micron caudal to the caudal end of the rostral ventromedial medulla). In these animals, increasing the stimulated area size from 4.8 to 18 cm2 resulted in a 35-45% reduction in the responses. In contrast, relative to responses elicited by 4.8 cm2 stimuli, responses to 18 cm2 were unchanged or even increased in animals with transections at more caudal level and in spinal animals. Inhibitions of the C-fiber responses elicited by heterotopic noxious heat stimulation were in the 70-80% range during conditioning in sham-operated animals and in animals with rostral brain stem transections. Such effects were reduced significantly (residual inhibitions in the 10-20% range) in animals with transections >500 micron caudal to the caudal end of the rostral ventromedial medulla and in spinal animals. It is concluded that the caudal medulla constitutes a key region for the expression of negative feed-back mechanisms triggered by both spatial summation of noxious inputs and heterotopic noxious inputs.

Video-assisted thoracoscopic surgery for right middle lobectomy in children

This case-control study was designed to evaluate the potential advantages and disadvantages of video-assisted thoracoscopic surgery for right middle lobectomy in children. Ten children (6.1 +/- 3.0 yr, mean +/- SD) who underwent right middle lobectomy under videoscopy were compared with 10 controls matched for age (6.8 +/- 3.5 yr) and operated by thoracotomy (muscle-sparing technique) during the same period by the same surgeon. Operating time was significantly longer in the videoscopy group than in the thoracotomy group (146 +/- 28 mn vs 100 +/- 27 mn, P < 0.001). Minimum oxygen saturation values were significantly higher in the videoscopy group whereas oxygen requirements did not differ between groups. Incidence of postoperative respiratory complications (mainly atelectasis) was similar in the two groups. No difference in postoperative analgesic requirements in the postoperative period was demonstrated. No real benefit or disadvantage of videoscopy over standard thoracotomy could be observed in this retrospective case-control study.

Priming doses of atracurium and vecuronium depress swallowing in humans

The administration of low doses of muscle relaxant may cause peripheral muscular weakness including difficulty in swallowing. In the present study, the effect of priming doses of atracurium and vecuronium on swallowing was studied. Sixty patients undergoing elective surgery under general anesthesia were divided randomly into four groups of 15 patients and received as a priming dose either vecuronium (10 or 15 micrograms/kg) or atracurium (50 or 75 micrograms/kg). Swallowing muscle activity was measured by electromyography using submental surface electrodes. Swallowing was initiated by administration of 0.3 ml distilled water through an oral catheter. Swallowing reflex was determined by measuring the latency time (i.e., time from water administration to start of EMG activity of glossal muscles). Swallowing activity was determined by integration of the EMG of glossal muscles during swallowing. Peripheral muscle strength was determined by hand grip strength. Swallowing reflex activity and peripheral muscle strength were measured before and 3 and 6 min after administration of vecuronium or atracurium. Latency time remained unchanged after any of the priming doses. Integrated EMG decreased significantly (P < .001) 3 and 6 min after all priming doses tested (42-75% of baseline value). Only after atracurium 75 micrograms/kg was the hand grip strength significantly decreased (P < .01). These results suggest that owing to its effect on swallowing, the priming dose should be used with caution.