Sevoflurane anesthesia and brain perfusion.

OBJECTIVE/AIM: To assess the impact of sevoflurane and anesthesia-induced hypotension on brain perfusion in children younger than 6 months. BACKGROUND: Safe lower limit of blood pressure during anesthesia in infant is unclear, and inadequate anesthesia can lead to hypotension, hypocapnia, and low cerebral perfusion. Insufficient cerebral perfusion in infant during anesthesia is an important factor of neurological morbidity. In two previous studies, we assessed the impact of sevoflurane anesthesia on cerebral blood flow (CBF) by transcranial Doppler (TCD) and on brain oxygenation by NIRS, in children ≤2 years. As knowledge about consequences of anesthesia-induced hypotension on cerebral perfusion in children ≤6 months is scarce, we conducted a retrospective analysis to compare the data of CBF and brain oxygenation, in this specific population. METHODS: We performed a retrospective analysis of data collected from our two previous studies. Baseline values of TCD or NIRS were recorded and then during sevoflurane anesthesia. From a database of 338 patients, we excluded all patients older than 6 months. Then, we compared physiological variables of TCD and NIRS population to ensure that the two groups were comparable. We compared rSO2 c and TCD measurements variation according to MAP value during sevoflurane anesthesia, using anova and Student-Newman-Keuls for posthoc analysis. RESULTS: One hundred and eighty patients were included in the analysis. TCD and NIRS groups were comparable. CBF velocities (CBFV) or rSO2 c reflects a good cerebral perfusion when MAP is above 45 mmHg. When MAP is between 35 and 45 mmHg, CBFV variation reflects a reduction of CBF, but rSO2 c increase is the consequence of a still positive balance between CMRO2 and O2 supply. Below 35 mmHg of MAP during anesthesia, CBFV decrease and rSO2 c variation from baseline is low. For each category of MAP and for the two groups, etCo2 and expired fraction of sevoflurane (FeSevo) were comparable (anova P > 0.05). CONCLUSION: In a healthy infant without dehydration, with normal PaCO2 and hemoglobin value, scheduled for short procedures, MAP is a good proxy of cerebral perfusion as we found that CBF assessed by CBFV and rSO2 c decreased proportionally with cerebral perfusion pressure. During 1 MAC sevoflurane anesthesia, maintaining MAP beyond 35 mmHg during anesthesia is probably safe and sufficient. But when MAP decreases below 35 mmHg, CBF decreases and rSO2 c variation from baseline is low despite CMRO2 reduction. In this situation, cerebral metabolic reserve is low and further changes of systemic conditions may be poorly tolerated by the brain.

Impact of sevoflurane anesthesia on brain oxygenation in children younger than 2 years.

OBJECTIVE/AIM: To assess the impact of sevoflurane and anesthesia-induced hypotension on brain oxygenation in children younger than 2 years. BACKGROUND: Inhalational induction with sevoflurane is the most commonly used technique in young children. However, the effect of sevoflurane on cerebral perfusion has been only studied in adults and children older than 1 year. The purpose of this study was to assess the impact of sevoflurane anesthesia on brain oxygenation in neonates and infants, using near-infrared spectroscopy. METHODS: Children younger than 2 years, ASA I or II, scheduled for abdominal or orthopedic surgery were included. Induction of anesthesia was started by sevoflurane 6% and maintained with an expired fraction of sevoflurane 3%. Mechanical ventilation was adjusted to maintain an endtidal CO2 around 39 mmHg. Brain oxygenation was assessed measuring regional cerebral saturation of oxygen (rSO2 c), measured by NIRS while awake and 15 min after induction, under anesthesia. Mean arterial pressure (MAP) variation was recorded. RESULTS: Hundred and ninety-five children were included. Anesthesia induced a significant decrease in MAP (-27%). rSO2 c increased significantly after induction (+18%). Using children age for subgroup analysis, we found that despite MAP reduction, rSO2 c increase was significant but smaller in children ≤ 6 months than in children >6 months (≤ 6 months: rSO2 c = +13%, >6 months: rSO2 c = +22%; P < 0.0001). Interindividual comparison showed that, during anesthesia at steady-state with comparable CMRO2, rSO2 c values were significantly higher when MAP was above 36 mmHg. And the higher the absolute MAP value during anesthesia was, the higher the rSO2 c was. We observed a rSO2 c variation ≤ 0 in 21 patients among the 195 studied, and the majority of these patients were younger than 6 months (n = 19). No increase or decrease of rSO2 c during anesthesia despite reduction of CMRO2 can be explained by a reduction of oxygen supply. Using the ROC curves, we determined that the threshold value of MAP under anesthesia, associated with rSO2 c variation ≤ 0%, was 39 mmHg in all the studied population (AUC: 0.90 ± 0.02; P < 0.001). In children younger than 6 months, this value of MAP was 33 mmHg, and 43 mmHg in children older than 6 months. CONCLUSION: Despite a significant decrease of MAP, 1 MAC of sevoflurane induced a significant increase in regional brain oxygenation. But subgroup analysis showed that MAP decrease had a greater impact on brain oxygenation, in children younger than 6 months. According to our results, MAP value during anesthesia should not go under 33 mmHg in children ≤6 months and 43 mmHg in children >6 months, as further changes in MAP, PaCO2 or hemoglobin during anesthesia may be poorly tolerated by the brain.

Latex allergy in children: modalities and prevention.

Allergic or immediate hypersensitivity reactions to latex have been reported in children with increasing frequency in the past. The reported prevalence varies greatly depending upon the population studied and the methods used to detect sensitization. Children's subpopulations at particular risk include: atopics, individuals with spina bifida, children undergoing surgical procedure during the neonatal period and individuals who required frequent surgical instrumentations. Latex allergy is also an important medical issue, particularly for healthcare personnel. Sensitization mainly occurs by wound or mucosal contact with latex devices during surgery or by inhalation of airborne allergens released from powdered latex gloves. Regarding diagnosis, the medical history, skin prick test and search for specific serum IgE are crucial but cost effective. The development of a guide listing latex-containing drugs is essential for the primary prevention of allergic reactions. Immunotherapy or specific premedication seems not effective in preventing the risk of anaphylaxis during the perioperative course. The most effective strategy to decrease the incidence of latex sensitization is complete avoidance. This strategy is efficient in patients and also in health care workers and has been applied since 2002 in our pediatric surgical hospital. One of major problem with the latex-free gloves was that surgeons find them considerably more difficult to work with. But today, manufacturers made considerable effort and free-latex gloves with an equal tactile sensation than the latex-gloves are now available. The extra cost of free latex gloves is well counterbalanced as allergen test, long stay hospital for allergic reaction, and worker's compensation are no longer needed. Since the introduction of this program in our institution, no allergic reaction to latex has been reported in 25000 anesthetized children or with the health care workers.

Patient-controlled regional analgesia is effective in children: a preliminary report.

PURPOSE: To report a preliminary analysis of prospectively recorded data in 27 children in whom patient-controlled regional analgesia (PCRA) was used for postoperative pain control following lower limb surgery. METHODS: Under general anesthesia, perineural catheters (popliteal and fascia iliaca compartment block) were inserted and infused with ropivacaine 0.2% (0.02 mL.kg(-1).hr(-1)). Additional demand doses were left to the child's discretion (0.1 mL.kg(-1)and a 30-min lockout interval). RESULTS: The average total dose of ropivacaine administered was 4.9 +/- 2 mg.kg(-1)over 48 hr. Visual analogue scale and Children's Hospital of Eastern Ontario Pain Scale scores were always inferior to 5/10 and 6/13, respectively. Motor block was observed in two children and two children needed rescue analgesia. CONCLUSIONS: Our preliminary observations indicate that PCRA in children provides satisfactory postoperative pain relief following lower limb surgery.

Patient-controlled epidural analgesia versus continuous epidural infusion with ropivacaine for postoperative analgesia in children.

UNLABELLED: Epidural ropivacaine infusion has been used in children; however, patient-controlled epidural analgesia (PCEA) has not been evaluated in the pediatric population. In this study, we compared the clinical efficiency of PCEA and of continuous epidural infusion analgesia (CEA) in children. Forty-eight children undergoing orthopedic surgery were randomized to receive PCEA or CEA with ropivacaine 0.2%. All patients underwent a standard general anesthetic. Children also received ketoprofen and propacetamol. Pain scores and side effects were recorded for 48 h. If the visual analog score scale score was >4 of 10, analgesia was considered inadequate, and rescue treatment was administered. Both groups obtained effective pain relief. Children in the PCEA group received significantly less local anesthetic than those in the CEA group (0.20 +/- 0.08 mg x kg(-1) x h(-1) versus 0.40 +/- 0.08 mg x kg(-1) x h(-1); P < 0.001). Motor effects, supplemental analgesic requirements, and side effects did not differ. We concluded that PCEA with ropivacaine 0.2% can provide adequate postoperative analgesia for pediatric orthopedic procedures with smaller dose requirements than CEA. IMPLICATIONS: We studied patient-controlled epidural analgesia (PCEA) and continuous epidural infusion analgesia (CEA) with 0.2% ropivacaine during the postoperative period in children. We found that either PCEA or CEA with plain ropivacaine 0.2% provided adequate pain relief in children during the first 48-h postoperative course. However, adequate analgesia was obtained with 50% less volume infused with PCEA compared with CEA.

Risk factors for airway complications during general anaesthesia in paediatric patients.

BACKGROUND: Although airway complications are a frequent problem during paediatric anaesthesia, no study has prospectively identified risk factors for adverse respiratory events during airway management when LMA trade mark (laryngeal mask airway), face mask (FM) or a tracheal tube (TT) are used. METHODS: A prospective study was performed at a university hospital's paediatric centre. Preoperative information included recent history of respiratory infection and type of surgery. Intraoperative information included the identification of the device user, the duration of anaesthesia and the type of airway device used. Adverse respiratory events during the perioperative and postoperative periods were registered. One thousand nine hundred and ninety-six patients were included (mean age 6.45 +/- 2.9 years). RESULTS: Airway complications occurred in 10.2% of the patient for LMA (72/704), 4.7% for FM (19/401) and 7.4% (66/891) for TT. Using a stepwise logistic regression, three independent risk factors were identified: age < 6 years, odds ratio (OR) 1.84, 95% CI (1.21-2.80); use of LMA, OR 2.32, 95% CI (1.29-4.17); presence of respiratory infections (RI) before the procedure, OR 3.72, 95% CI (2.3-5.99). CONCLUSIONS: Age < 6 years, recent RI and the use of the LMA were identified as independent factors associated with an increased risk of airway complications.