Understanding time to peak effect of propofol as sole agent on bispectral index in children aged 2-12 years.

BACKGROUND: The pharmacodynamics of propofol in children have previously been described with the proprietary bispectral index (BIS) as an effect-site marker, and it has been suggested that the rate of onset of propofol might be age dependent, that is, a shorter time to peak effect in younger children. However, these analyses were potentially confounded by co-administered drugs, in particular opioids and benzodiazepines. Thus, the goal of this prospective study was to characterize the influence of age and weight on the onset of hypnotic effects from propofol, reflected by the time to peak of propofol effect-site concentration in the absence of additional drugs. METHODS: A total of 46 healthy children aged 2-12 years presenting for elective surgery were included in our observational cohort study. Solely propofol was administered via a target-controlled infusion pump programmed with the Paedfusor pharmacokinetic model. The BIS and infusion pump data were recorded. The effect of an induction "bolus" was recorded having stopped the pump once a propofol plasma target concentration of 7 µg.mL-1 was achieved. A direct-response and an indirect-response model in the context of nonlinear mixed-effects modeling was used to characterize and compare BIS data in children aged 2-6 years and older children aged 8-12 years. RESULTS: Time to peak of propofol effect-site concentration had a difference (p-value <.01) for age and weight, that is 84 [74, 96] (median [IQR] secs for children aged 2-6 years vs. 99 [91, 113] secs for children aged 8-12 years and 82 [71, 95] secs for weight 11-25 kg vs. 99 [91, 114] secs for weight 30-63 kg). The plasma effect-site equilibration rate constant for propofol had a heterogeneous distribution with a median of 2.36 (IQR: 2.05-2.93; range: 0.83-7.31) per minute but showed a weight-dependent effect in patients with weight below 45 kg. CONCLUSIONS: In children, the age and weight have an influence on time to peak effect of propofol. In the absence of opioids and benzodiazepines, time to peak effect was approximately 20% longer in children aged 8-12 years as compared to younger children. Such clinically relevant age and weight effects are an important consideration in the individualized titration of propofol dosing.

The number of comorbidities as an important cofactor to ASA class in predicting postoperative outcome: An international multicentre cohort study.

BACKGROUND: Multimorbidity is a growing burden in our ageing society and is associated with perioperative morbidity and mortality. Despite several modifications to the ASA physical status classification, multimorbidity as such is still not considered. Thus, the aim of this study was to quantify the burden of comorbidities in perioperative patients and to assess, independent of ASA class, its potential influence on perioperative outcome. METHODS: In a subpopulation of the prospective ClassIntra® validation study from eight international centres, type and severity of anaesthesia-relevant comorbidities were additionally extracted from electronic medical records for the current study. Patients from the validation study were of all ages, undergoing any type of in-hospital surgery and were followed up until 30 days postoperatively to assess perioperative outcomes. Primary endpoint was the number of comorbidities across ASA classes. The associated postoperative length of hospital stay (pLOS) and Comprehensive Complication Index (CCI®) were secondary endpoints. On a scale from 0 (no complication) to 100 (death) the CCI® measures the severity of postoperative morbidity as a weighted sum of all postoperative complications. RESULTS: Of 1421 enrolled patients, the mean number of comorbidities significantly increased from 1.5 in ASA I (95% CI, 1.1-1.9) to 10.5 in ASA IV (95% CI, 8.3-12.7) patients. Furthermore, independent of ASA class, postoperative complications measured by the CCI® increased per each comorbidity by 0.81 (95% CI, 0.40-1.23) and so did pLOS (geometric mean ratio, 1.03; 95% CI, 1.01-1.06). CONCLUSIONS: These data quantify the high prevalence of multimorbidity in the surgical population and show that the number of comorbidities is predictive of negative postoperative outcomes, independent of ASA class.

Special Anaesthetic Considerations for Brain Tumour Surgery in Children.

Brain tumours are among the most common neoplasm in children. Therefore, paediatric anaesthesiologists face the challenge of neurosurgical interventions in all age groups. To minimize perioperative mortality and morbidity, a comprehensive understanding of age-dependent differences in anatomy and cerebrovascular physiology is a mandatory prerequisite. Advances in subspeciality training in paediatric neurosurgery and paediatric anaesthesia may improve clinical outcomes and advance communication between the teams.

Impact of high concentrations of sevoflurane on laryngeal reflex responses.

BACKGROUND: Exaggerated defensive upper airway reflexes, particularly laryngospasm, may cause hypoxemic damage, especially in children. General clinical experience suggests that laryngeal reflex responses are more common under light levels of anesthesia, and previous clinical studies have shown an inverse correlation between laryngeal responsiveness and depth of hypnosis. However, this seems to be less obvious in children anesthetized with sevoflurane. The aim of this study was to assess the impact of high concentrations of sevoflurane on laryngeal and respiratory reflex responses in spontaneously breathing children. Accordingly, we tested the hypothesis that laryngeal and respiratory reflex responses were completely suppressed in spontaneously breathing children when anesthetized with sevoflurane 4.7% (=MACED95Intubation ) as compared with sevoflurane 2.5% (=1 MAC). METHODS: In this prospective observational study, we tested the hypothesis that the incidence of laryngospasm evoked by laryngeal stimulation is diminished under high concentrations of sevoflurane. Following Ethics approval, trial registration, and informed consent, 40 children (3-7 years) scheduled for elective surgery participated in the trial. All children received sevoflurane 2.5% (1 MAC) and 4.7% (ED95Intubation ) in random order with 5-min equilibration between the states. Under both conditions, distilled water was sprayed under bronchoscopic view onto the larynx. Potential laryngeal and respiratory reflex responses were assessed offline by a blinded reviewer. RESULTS: Laryngospasm (episodes lasting >10 s) occurred in 12/38 (32%) of the patients anesthetized with sevoflurane 2.5%, vs 7/38 (18%) in those anesthetized with sevoflurane 4.7% (difference: OR 3.5; 95% CI [0.72-16.84], P = 0.18). All other reflex responses (coughing, expiration reflexes, and spasmodic panting) were infrequent and were similar among the examined concentrations. CONCLUSION: Against our hypothesis, laryngospasm could still be observed in 18% of children under the higher concentration of sevoflurane (4.7%, ED95Intubation ).

Topical Lidocaine Does Not Exaggerate Laryngomalacia in Infants During Flexible Bronchoscopy Under Propofol Anesthesia.

BACKGROUND: Topical lidocaine has been found to result in overestimation of the severity of laryngomalacia in infants undergoing flexible bronchoscopy under conscious sedation with midazolam and nalbuphine. This effect has never been confirmed and may depend on the level of sedation and the drugs used. We assessed the effect of topical lidocaine on laryngomalacia in infants undergoing flexible bronchoscopy under general anesthesia with propofol. METHODS: Thirteen infants with congenital stridor referred to diagnostic flexible video-bronchoscopy were studied under propofol anesthesia before and 3 minutes after topical lidocaine administration to the larynx at a dose of 3 mg/kg body weight. Laryngomalacia was scored using 60 seconds video recordings of the larynx before and after lidocaine administration in random order by 2 independent blinded observers using the previously described arytenoid score (AS), epiglottis score (ES), and the total score (TS=AS+ES). RESULTS: No significant differences in AS, ES, and laryngomalacia score were found between the prelidocaine and postlidocaine assessments by the 2 raters. The intraclass correlation coefficients were 0.995 (95% confidence interval, 0.986-0.998) and 0.975 (0.930-0.991) and 0.989 (0.971-996) for AS, ES, and TS, respectively. CONCLUSIONS: The assessment of laryngomalacia is not affected by topical lidocaine under propofol anesthesia. The lidocaine effect on laryngomalacia may vary depending on the medication regime used and the depth of procedural sedation.

Endoscopic pediatric neurosurgery: implications for anesthesia.

Endoscopic surgery is increasingly utilized in neurosurgery for all pediatric age groups. Endoscopic intraventricular neurosurgery represents a unique approach to intracranial pathology but may cause a unique set of limitations and potential complications. Important endoscopic neurosurgical techniques and their indications, perioperative anesthesia management, complications, and success rates are reviewed with special emphasis on endoscopic third ventriculostomy and endoscopic-assisted strip craniectomy in early infancy. Despite encouraging short- and long-term results of early pediatric endoscopic neurosurgery, multicenter randomized studies will be needed to further determine safety and the effect on cognitive development and quality of life.

Severe anaphylactic shock due to ethylene oxide in a patient with myelomeningocele: successful exposure prevention and pretreatment with omalizumab.

Ethylene oxide (EO) is a highly reactive gas widely used for sterilization of medical devices, for example, plastic materials and ventriculoperitoneal shunts. Allergic reactions to EO are rare and have been observed mainly in patients during hemodialysis and myelomeningocele patients. We describe severe anaphylaxis to EO in a patient with myelomeningocele during general anesthesia. A detailed description is provided about the prevention measures aimed at reducing exposure to EO including a novel approach by resterilization with plasma. Also, pretreatment with omalizumab was implemented for the first time in such a case. With these measures, further surgeries in our patient were uneventful.

The effect of deep vs. awake extubation on respiratory complications in high-risk children undergoing adenotonsillectomy: a randomised controlled trial.

CONTEXT: There is ongoing debate regarding the optimal timing for tracheal extubation in children at increased risk of perioperative respiratory adverse events, particularly following adenotonsillectomy. OBJECTIVE: To assess the occurrence of perioperative respiratory adverse events in children undergoing elective adenotonsillectomy extubated under deep anaesthesia or when fully awake. DESIGN: Prospective, randomised controlled trial. SETTING: Tertiary paediatric hospital. PATIENTS: One hundred children (<16 years), with at least one risk factor for perioperative respiratory adverse events (current or recent upper respiratory tract infection in the past 2 weeks, eczema, wheezing in the past 12 months, dry nocturnal cough, wheezing on exercise, family history of asthma, eczema or hay fever as well as passive smoking). INTERVENTION: Deep or awake extubation. MAIN OUTCOME MEASURE: The occurrence of perioperative respiratory adverse events (laryngospasm, bronchospasm, persistent coughing, airway obstruction, desaturation <95%). RESULTS: There were no differences between the two groups with regard to age, medical and surgical parameters. The overall incidence of complications did not differ between the two groups; tracheal extubation in fully awake children was associated with a greater incidence of persistent coughing (60 vs. 35%, P = 0.028), whereas the incidence of airway obstruction relieved by simple airway manoeuvres in children extubated while deeply anaesthetised was greater (26 vs. 8%, P = 0.03). There was no difference in the incidence of oxygen desaturation lasting more than 10 s. CONCLUSION: There was no difference in the overall incidence of perioperative respiratory adverse events. Both extubation techniques may be used in high-risk children undergoing adenotonsillectomy provided that the child is monitored closely in the postoperative period. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12609000387224.

Does topical lidocaine before tracheal intubation attenuate airway responses in children? An observational audit.

BACKGROUND: The use of topical lidocaine, applied to the airways with various administration techniques, is common practice in pediatric anesthesia in many institutions. However, it remains unclear whether these practices achieve their intended goal of reducing the risk of perioperative respiratory adverse events (PRAE) in children undergoing elective endotracheal intubation without neuromuscular blockade (NMB). The relative frequency of PRAE (laryngospasm, coughing, desaturation <95%) associated with no use of topical airway lidocaine (TAL), with TAL sprayed directly onto the vocal cords, and TAL administered blindly into the pharynx was assessed. METHODS: This prospective audit involved 1000 patients undergoing general anesthesia with elective endotracheal intubation without NMB. Patients with suspected difficult airways or undergoing airway surgery were excluded. The use of TAL and the mode of administration were recorded. Respiratory adverse events were recorded in the perioperative period. RESULTS: Two hundred and fifty-four patients had the vocal cords sprayed under direct vision, 236 had lidocaine blindly dripped into the pharynx, and 510 received no TAL. The mean age and known risk factors for PRAE (asthma, recent upper respiratory tract infection (≤2 weeks), passive smoking, hayfever, past or present eczema, nocturnal dry cough) were similar among the groups. The proportion of patients with desaturation (<95%) between induction of anesthesia and discharge from the recovery room was higher in the two groups who received TAL (data combined for all patients receiving lidocaine regardless of administration method, P = 0.01) compared to those who received no TAL. No difference in the rates of laryngospasm (P = 0.13) or cough (P = 0.07) was observed among the groups. There was no difference in the rates of PRAE between the groups given TAL directly onto the vocal cords and in those whom received TAL blindly. CONCLUSIONS: The incidence of desaturation was higher in patients receiving TAL compared with children who did not. This association should perhaps be considered when contemplating the use of this technique.

Predictors of postoperative sore throat in intubated children.

BACKGROUND: The incidence of postoperative sore throat (POST) following intubation is not well defined in the pediatric population. The etiology is multifactorial and includes impairment of subglottic mucosal perfusion and edema as a result of the pressures exerted by cuffed or uncuffed tubes. AIM: To determine the incidence of, and risk factors for, POST in intubated children undergoing elective day-case surgery. METHODS: Five hundred patients aged 3-16 years were studied prospectively. Endotracheal tube (ETT) choice (cuffed or uncuffed) was left to the anesthetist. The cuff was inflated either until loss of audible leak or to a determined pressure using a cuff manometer. The research team then measured the cuff pressure (CP). POST incidence and intensity was determined by interviewing patients prior to discharge from the same day procedure unit. Chi-square testing and stepwise logistic regression were used to determine the predictors of POST. RESULTS: Of the 111 (22%) children developed a sore throat, 19 (3.8%) a sore neck, and 5 (1%) a sore jaw. 19% of patients with cuffed ETTs complained of sore throat compared with 37% of those intubated with an uncuffed ETT. The incidence of POST increased with CP; 0-10% at 0 cmH(2)O, 4% at 11-20 cmH(2)O, 20% at 21-30 cmH(2)O, 68% at CP 31-40 cmH(2)O, and 96% at CP >40 cmH(2)O. The ETT CP and use of uncuffed ETTs were univariate predictors of POST. CONCLUSIONS: Children intubated with uncuffed ETTs are more likely to have POST. ETT CP is positively correlated with the incidence of POST. When using cuffed ETTs, CP should be routinely measured intraoperatively.

Prospective study on central venous line associated bloodstream infections.

OBJECTIVE: To prospectively assess the incidence rates and characteristics of central venous line associated bloodstream infections (CLABSI) in one institution. METHODS: All patients with indwelling central venous catheters (CVC) between 1 April 2008 and 31 March 2009 were enrolled. The medical records of patients were reviewed and information on relevant characteristics entered into a standardised questionnaire. Central laboratory records were regularly checked for positive blood cultures in study patients. RESULTS: There were 209 CVC for a total of 14752 CVC days in 152 patients (88 males, 58%) including neonates and patients with surgical conditions and haemato-oncological and other underlying diseases. Median age at CVC insertion was 3 months (IQR 0-56 months). Fourteen CLABSI occurred in 13 patients. Overall CLABSI incidence (per 1000 CVC days) was 0.95 (9.71 for silastic percutaneous CVC, 7.65 for other CVC, 1.97 for Broviac, 0.18 for Port-a-cath). CVC remained in place for ≤ 14 days in 109 (52%) instances, 15-90 days in 45 (22%) instances and > 90 days in 55 (26%) instances. The incidence of CLABSI in these three categories was 3.36, 4.36 and 0.47, respectively. Predominating cultured organisms were coagulase-negative staphylococci (N=3), S. aureus (N=3), and Enterococcus spp. (N=3). CONCLUSIONS: CLABSI incidence varied by type of catheter and type of patient, with the highest risk in neonates (with silastic percutaneous CVC) and by far the lowest risk for Port-a-cath CVC. Prophylactic measures to reduce CLABSI should be tailored to individual types of catheters and patient characteristics.

Incidence of sore throat in children following use of flexible laryngeal mask airways - impact of an introducer device.

BACKGROUND: Insertion of a flexible laryngeal mask airway (FLMA) is more difficult and therefore might result in a higher risk for trauma to the upper airway. To facilitate the insertion of FLMA, the use of an introducer device (Portex Limited, Hythe, Kent, UK) was promoted. However, the impact of the use of this device on the occurrence of postoperative sore throat is unknown. METHODS: Four hundred children (3-21 years) undergoing elective ambulatory surgery were consecutively included in this study. In 196 cases, the FLMA was inserted using an introducer device. The FLMA cuff was then inflated and the pressure adjusted to below 60 cmH(2)O (according to manufacturers guidelines) using a calibrated cuff manometer (Portex Limited). Three types of FLMA were available: FLMA classic, FLMA unique (both FLMA PacMed, Richmond, Victoria, Australia) and FLMA ProBreathe (Well Lead Medical Co Ltd., Hualong, Guangzhou, China). Prior to discharge, patients' pain was assessed using an age appropriate scale. RESULTS: Thirteen children (3.3%) developed sore throat, two (0.5%) sore neck and three (0.75%) sore jaw. Of those that developed sore throat, seven had a FLMA inserted with an introducer, six without an introducer. Using a laryngeal mask airways (LMA) with a polyvinyl chloride (PVC), surface was associated with a higher risk for sore throat compared with an LMA with a silicone surface (P = 0.0002). CONCLUSION: In this study with controlled low cuff pressures, the incidence of sore throat was low. The use of an introducer device did not affect the rate of sore throat.

Fentanyl does not reduce the incidence of laryngospasm in children anesthetized with sevoflurane.

BACKGROUND: The modifying effects of fentanyl on protective airway reflexes have not been characterized in children. The aim of this study was to assess the impact of increasing doses of fentanyl on laryngeal reflex responses in children anesthetized with sevoflurane. The authors hypothesized that the incidence of laryngospasm evoked by laryngeal stimulation is reduced with increasing doses of fentanyl. METHODS: Sixty-three children, aged 2-6 yr, scheduled for elective surgery, were anesthetized with sevoflurane (1 minimum alveolar concentration). By using an established technique, laryngeal and respiratory responses were elicited by spraying distilled water on the laryngeal mucosa: (1) before the administration of fentanyl, (2) after the administration of 1.5 microg/kg fentanyl, and (3) after the administration of a second dose of 1.5 microg/kg fentanyl. In 10 children, serving as a time control, three successive laryngeal stimulations were performed without the administration of fentanyl. The responses were assessed by a blinded reviewer. RESULTS: The study was completed in 60 patients. The incidence of laryngospasm was not reduced when up to two successive doses of 1.5 microg/kg fentanyl were administered. The incidence of laryngospasm lasting for more than 10 s was 26% before receiving fentanyl, 31% after recieving1.5 microg/kg fentanyl, and 18% after receiving a second dose of 1.5 microg/kg fentanyl (P = 0.36 and 0.78, respectively). This response was similar to that observed in the time control group (P = 0.21). CONCLUSION: Two successive doses of 1.5 microg/kg fentanyl did not effectively prevent laryngospasm in children, aged 2-6 yr, anesthetized with sevoflurane.

Laryngeal mask airways--to inflate or to deflate after insertion?

BACKGROUND: Hyperinflation of the laryngeal mask airway (LMA) cuff is known to be a risk factor for airway morbidity and increased leakage around the LMA. While the manufacturers' recommendation is to inflate the cuff with the maximum recommended volumes and/or to adjust the cuff pressure to <60 cmH2O, cuff pressures below 40 cmH2O have been shown to be associated with a minimal rate of sore throat and minimal leakage. However, it remains to be determined whether inflation or deflation is needed to achieve favorable pressures. Therefore, we assessed the need for cuff-volume adjustment following insertion of the LMA unchanged straight from the sterile packaging in a prospective audit. METHODS: One thousand children (0-16 years) undergoing elective surgery were consecutively included in this quality of care audit. After taking the LMA from its sterile packaging, the LMA cuff was emptied and the amount of air recorded. Then, the same amount of air was returned into the LMA, the LMA was inserted into the patient, and the cuff pressure was measured using a calibrated cuff manometer. RESULTS: Following insertion of the LMA (without further inflation or deflation of the cuff), 20.5% of children had cuff pressures > or = 60 cmH2, while 55.7% had LMA cuff pressures <40 cmH2O. Cuff pressures were also significantly higher in size 1 LMAs (66.6% had cuff pressures > or = 60 cmH2O and 2% <40 cmH2O) compared with all other sizes (P < 0.05). Furthermore, cuff pressures in LMAs with a poly vinyl chloride (PVC) surface were higher compared to LMAs with a silicone surface (65.2% > or = 60 cmH2O and 9.3% <40 cmH2O vs 9% > or = 60 cmH2O and 67.6% <40 cmH2O, respectively). CONCLUSIONS: This study demonstrates that LMAs, particularly when using small-sized LMAs or LMAs with a more rigid PVC surface, need to be deflated following insertion of the device rather than inflated to avoid cuff hyperinflation. Hence, cuff pressures should be measured routinely using a manometer to minimize potential pressure-related airway complications.

Salbutamol premedication in children with a recent respiratory tract infection.

BACKGROUND: Premedication with beta-2 agonists (e.g. salbutamol) is effective in preventing increases in total respiratory resistance and in decreasing the incidence of perioperative bronchospasm in asthmatic children. Because children with recent respiratory tract infection (RTI) exhibit bronchial hyperreactivity similar to that observed in asthmatic children, the use of salbutamol in children with RTI has become popular among pediatric anesthetists for the prevention of perioperative respiratory adverse events (PRAE). In a prospective observational study, we therefore assessed the usefulness of salbutamol premedication on the occurrence of PRAE. METHODS: Results from 600 children (0-16 years) undergoing general anesthesia were analyzed: 200 children with a recent RTI who received preoperative salbutamol 10-30 min prior to surgery, 200 children with a recent RTI without salbutamol premedication, and 200 children without a RTI during the last 4 weeks. All PRAE (laryngospasm, bronchospasm, oxygen desaturation [<95%], severe coughing) were recorded. RESULTS: Children with a recent RTI who received salbutamol demonstrated a significantly reduced incidence of perioperative bronchospasm (5.5% vs 11%, P = 0.0270) and severe coughing (5.5% vs 11.5%, P = 0.0314) compared with children who had an RTI but did not receive salbutamol. However, healthy children presented with the lowest rate (bronchospasm 1.5%, severe coughing 4.5%) of respiratory complications compared with children with a recent RTI independent whether or not they received salbutamol preoperatively. CONCLUSIONS: The results from this audit suggest that children with a history of a recent RTI have significantly less PRAE following a premedication with salbutamol compared with no premedication. Therefore, premedication with salbutamol might be considered in children with recent RTI.

Impact of laryngeal mask airway cuff pressures on the incidence of sore throat in children.

BACKGROUND: Hyperinflation of laryngeal mask airway cuffs can cause harm to the upper airway mainly by exerting high pressures on pharyngeal and laryngeal structures thus impairing mucosal perfusion. Although cuff manometers can be used to guide the monitoring of cuff pressures, their use is not routine in many institutions. In a prospective audit, we assessed the incidence of sore throat following day-case-surgery in relation to the intracuff pressure within the laryngeal mask airway. METHODS: Four hundred children (3-21 years) were consecutively included in this study. The laryngeal mask airway was inflated as deemed necessary by the attending anesthetist. Cuff pressures were measured using a calibrated cuff manometer (Portex Limited, Hythe, Kent, UK, 0-120 cm H2O, pressures exceeding the measurement range were set at 140 cm H2O for statistical purposes) at induction of anesthesia. RESULTS: Forty-five children (11.25%) developed sore throat, 32 (8%) sore neck and 17 (4.25%) sore jaw. Of those that developed sore throat, 56.5% had cuff pressures exceeding >100 cm H2O. In contrast, when cuff pressures were <40 cm H2O, there were no episodes of sore throat, whilst there was only a 4.6% occurrence of sore throat if cuff pressures were between 40-60 cm H2O. CONCLUSION: We have demonstrated that intra cuff pressure in laryngeal mask airways is closely related to the development of sore throat with higher pressures increasing its likelihood. Hence, cuff pressures should be measured routinely using a manometer to minimize the incidence of sore throat.

Effect of cardiopulmonary bypass and aortic clamping on functional residual capacity and ventilation distribution in children.

OBJECTIVE: To characterize factors that contribute to lung function impairment after cardiopulmonary bypass, we assessed functional residual capacity and ventilation homogeneity during the perioperative period in children with congenital heart disease who are to undergo surgical repair. METHODS: Functional residual capacity and lung clearance index were measured by using a sulfur hexafluoride washout technique in 24 children (aged 0-10 years). Measurements of functional residual capacity and ventilation distribution were performed after induction of anesthesia, at different stages of the surgical procedure, and up to 90 minutes after skin closure. Anesthesia was standardized, and ventilator settings, including the fraction of inspired oxygen, were kept constant throughout the study period. RESULTS: Sternotomy and retractor insertion led to a significant increase in functional residual capacity (mean [SD], 24% [14%]), followed by a similar percentage decrease in the resting volume after a significant reduction in pulmonary blood flow during cardiopulmonary bypass with aortic clamping. Although reestablishing pulmonary blood flow increased functional residual capacity (10% [6%]), chest closure led to a decrease in functional residual capacity of 36% (14%) that only slightly improved during the first 90 minutes after surgical intervention. Changes in lung clearance index were affected conversely compared with changes in functional residual capacity at all assessment times. CONCLUSIONS: These results confirmed that chest wall condition and pulmonary circulation affect lung volumes and ventilation homogeneity. Although opening of the chest wall improved alveolar recruitment and ventilation homogeneity, blood flow appeared essential for alveolar stability, presumably by exerting a tethering force caused by the filled capillaries on the alveolar walls and therefore contributing to an increase in resting lung volume.

Decrease in functional residual capacity and ventilation homogeneity after neuromuscular blockade in anesthetized preschool children in the lateral position.

BACKGROUND: While functional residual capacity (FRC) is reduced in children undergoing general anesthesia, the lateral position leads to an increase in FRC compared with the supine position. The impact of neuromuscular blockade remains unknown. We tested the hypothesis that neuromuscular blockade leads to a decrease in FRC and increase in lung clearance index (LCI) while the application of positive endexpiratory pressure (PEEP) of 6 cmH(2)O leads to a restoration in both parameters. METHODS: After approval of the local Ethics Committee, we studied 18 preschool children (2-6 years) without cardiopulmonary disease, who were scheduled for elective surgery. Anesthesia was standardized using propofol and fentanyl. FRC and LCI were calculated by a blinded observer using a SF6 multibreath washout technique with an ultrasonic transit-time airflow meter (Exhalyzer D). Measurements were taken in the left lateral position (PEEP 3 cmH2O) after 1. intubation with a cuffed tracheal tube, 2. neuromuscular blockade with rocuronium, and 3. the additional application of PEEP (6 cmH2O). RESULTS: Functional residual capacity mean (sd) decreased from 31.6 (4.4) ml.kg(-1) to 27.6 (4.2) ml.kg(-1) (P<0.001) following neuromuscular blockade while the LCI increased from 6.54 (0.6) to 7.0 (0.6) (P

Should the use of modified Jackson Rees T-piece breathing system be abandoned in preschool children?

BACKGROUND: The Jackson Rees breathing system is commonly used for bag and mask ventilation in preschool children, although the lack of a pressure release valve can increase the risk of gastric insufflation. Therefore, we investigated the impact of bag and mask ventilation with a Jackson Rees system on functional residual capacity (FRC) and ventilation homogeneity and evaluated the effect of the level of training of the anesthesiologist in charge. METHODS: Functional residual capacity and ventilation homogeneity were measured in 74 children (1-6 years) undergoing general surgery and the level of training of the anesthesiologist was recorded. FRC was measured (i) after intubation and (ii) after gastric emptying. Sixty-four children were ventilated using a Jackson Rees system, whereas 10 children were ventilated using a circle system to compare these two breathing systems in the second phase of the protocol. RESULTS: Functional residual capacity and ventilation homogeneity increased in all patients following gastric emptying with the highest improvement (25%) being observed when nurse students were in charge of the ventilation with the Jackson Rees system. The lowest changes in FRC and ventilation homogeneity were observed when pediatric consultants were in charge, whereas ventilation by the pediatric nurse anesthetists led to significant gastric gas insufflation. However, the circle system was associated with significantly less gastric insufflation than the Jackson Rees system. CONCLUSIONS: The efficacy of bag and mask ventilation was highly dependent on the training of the anesthesiologist with consultants demonstrating significantly better skills than any of the other groups. As the circle system is associated with a much steeper learning curve than the Jackson Rees system, its use in daily routine practice may prevent ventilatory impairment induced by gastric insufflation.