Impact of sevoflurane anesthesia on cerebral blood flow in children younger than 2 years.

OBJECTIVE/AIM: To assess the impact of sevoflurane and anesthesia-induced hypotension on cerebral blood flow (CBF) 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 is to assess the impact of sevoflurane anesthesia on CBF in neonates and infants, using transcranial Doppler (TCD) sonography. METHODS: Children younger than 2 years, ASA I or II, 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 controlled to maintain an end tidal CO(2) around 39 mmHg. CBF was assessed by measuring the velocities (systolic velocity SVmca, diastolic velocity DVmca and mean velocity MVmca) in the proximal segment of the middle cerebral artery (mca) in children awake and then 15 min after induction. Mean arterial pressure (MAP) variation was noted. RESULTS: One hundred and thirteen children were included. We observed a significant decrease in MAP (-30%). DVmca decreased and pulsatility index increased significantly after induction. Subgroup analysis according to age showed that in infants older than 6 months, despite a significant reduction in MAP, there was no change in CBF velocity (CBFV) as measured by TCD sonography, until MAP dropped below 40% of baseline. In infants younger than 6 months, a significant decrease in MAP was observed which was associated with a significant variation in CBFV. In this population, when CBFV start to decrease, MAP under sevoflurane anesthesia was 38 mmHg or -20% from baseline value. CONCLUSION: Our results are in favor of a reduction in CBF after induction with sevoflurane in children younger than 6 months. This population is more sensitive to MAP decrease than older children because of a lower limit of cerebral autoregulation, and this limit may be 38 mmHg with sevoflurane anesthesia.

Effects of subhypnotic doses of propofol on gastric emptying in volunteers.

BACKGROUND: Drugs which accelerate gastric emptying (GE) decrease nausea and vomiting. This could contribute to the antiemetic potential of subhypnotic doses of propofol. On the contrary, subhypnotic doses of propofol used for sedation could decrease GE and thus favor regurgitation and pulmonary inhalation. Therefore, the aim of this study was to assess the effect of low-dose propofol infusion on GE. METHODS: On three separate occasions, 10 volunteers received either a propofol infusion at a rate set to achieve a target plasma concentration of 0.5 microg/ml or equivalent volumes of 10% Intralipid(R) or 0.9% saline. GE for solids was measured by using the octanoic acid breath test. An acetaminophen absorption technique measured the GE rate for liquids. Blood samples were assayed for acetaminophen and propofol. Breath samples were analyzed for (13)CO(2) concentration by isotope-ratio mass spectrometry. Carbon dioxide production (VCO(2)) was measured instead of calculated by indirect calorimetry. Sedation was evaluated by the Bispectral Index of the electroencephalogram. RESULTS: Propofol blood concentrations were 0.32 +/- 0.20 and 0.45 +/- 0.18 microg/ml at 60 and 165 min, respectively. These concentrations were not sedative. Propofol or its solvent did not modify GE for solids or liquids. In all groups, differences in GE were obtained if measured VCO(2) was integrated in the formula instead of calculated VCO(2) (P < 0.002). CONCLUSIONS: Subhypnotic doses of propofol known to be antiemetic do not inhibit GE. These results suggest that the antiemetic properties of propofol are not peripheral and that propofol cannot be considered as a prokinetic agent. V(13)CO(2) must be measured instead of calculated to accurately determine GE.

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.

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.