Propofol or halothane anaesthesia for children with asthma: effects on respiratory mechanics

Effect of General Anesthesia Maintenance with Propofol or Sevoflurane on Fractional Exhaled Nitric Oxide and Eosinophil Blood Count: A Prospective, Single Blind, Randomized, Clinical Study on Patients Undergoing Thyroidectomy

Background: Nitric oxide (NO) is considered a means of detecting airway hyperresponsiveness, since even non-asthmatic patients experiencing bronchospasm intraoperatively or postoperatively display higher levels of exhaled NO. It can also be used as a non-invasive biomarker of lung inflammation and injury. This prospective, single-blind, randomized study aimed to evaluate the impact of two different anesthesia maintenance techniques on fractional exhaled nitric oxide (FeΝO) in patients without respiratory disease undergoing total thyroidectomy under general anesthesia. Methods: Sixty patients without respiratory disease, atopy or known allergies undergoing total thyroidectomy were randomly allocated to receive either inhalational anesthesia maintenance with sevoflurane at a concentration that maintained Bispectral Index (BIS) values between 40 and 50 intraoperatively or intravenous anesthesia maintenance with propofol 1% targeting the same BIS values. FeΝO was measured immediately preoperatively (baseline), postoperatively in the Postanesthesia Care Unit and at 24 h post-extubation with a portable device. Other variables measured were eosinophil blood count preoperatively and postoperatively and respiratory parameters intraoperatively. Results: Patients in both groups presented lower than baseline values of FeΝO measurements postoperatively, which returned to baseline measurements at 24 h post-extubation. In the peripheral blood, a decrease in the percentage of eosinophils was demonstrated, which was significant only in the propofol group. Respiratory lung mechanics were better maintained in the propofol group as compared to the sevoflurane group. None of the patients suffered intraoperative bronchospasm. Conclusions: Both propofol and sevoflurane lead to the temporary inhibition of NO exhalation. They also seem to attenuate systemic hypersensitivity response by reducing the eosinophil count in the peripheral blood, with propofol displaying a more pronounced effect and ensuring a more favorable mechanical ventilation profile as compared to sevoflurane. The attenuation of NO exhalation by both agents may be one of the underlying mechanisms in the reduction in airway hyperreactivity. The clinical significance of this fluctuation remains to be studied in patients with respiratory disease.

Propofol anesthesia for children undergoing magnetic resonance imaging: a comparison with isoflurane, nitrous oxide, and a laryngeal mask airway

BACKGROUND

Both propofol infusions with oxygen delivered through nasal cannula and isoflurane/N2O (nitrous oxide) delivered via a laryngeal mask airway (LMA) are used to provide anesthesia for children undergoing magnetic resonance imaging scans. We compared the incidence of adverse events and perioperative physiologic responses in children anesthetized with these 2 regimens.

METHODS

One hundred-fifty healthy children, ages 1 to 10 years, were randomized to receive either a propofol infusion (starting at 300 µg kg·min) with oxygen via nasal cannula (n = 75) or isoflurane with 70% N2O in oxygen delivered via an LMA (n = 75), both after a sevoflurane/N2O/oxygen induction. Adverse airway events, as well as hemodynamic, respiratory, and other physiologic responses were recorded during the magnetic resonance imaging scans and in the postanesthesia care unit by a single research nurse who was blind to the treatments. All parents were contacted postoperatively to complete a postanesthetic follow-up.

RESULTS

All 150 children completed their scans. The frequency of all adverse airway events during emergence and recovery after propofol (12%) was significantly less than that after isoflurane/N2O/LMA (49%) (95% confidence interval for the risk difference was 23%-50%) (P = 0.0001). Hemodynamic responses and recovery times for the 2 treatments were similar. Early recovery, defined as the time interval from admission to the postanesthesia care unit until eye opening and wakefulness (modified Aldrete score >5), after propofol was more rapid than that after isoflurane/N2O/LMA (P = 0.0001 and P = 0.0012, respectively). No scans had to be repeated.

CONCLUSIONS

The frequency of adverse airway events during emergence and recovery after propofol infusion with oxygen by nasal cannula is less than with isoflurane/N2O/LMA in children.

Volatile anesthetic rescue therapy in children with acute asthma: innovative but costly or just costly?

OBJECTIVES

To describe volatile anesthesia (VA) use for pediatric asthma, including complications and outcomes.

DESIGN

Retrospective cohort study.

SETTING

Children's hospitals contributing to the Pediatric Health Information System between 2004-2008.

PATIENTS

Children 2-18 years old with a primary diagnosis code for asthma supported with mechanical ventilation.

INTERVENTION

Those treated with VA were compared to those not treated with VA or extracorporeal membrane oxygenation. Hospital VA use was grouped as none, <5%, 5-10% and >10% among intubated children.

MEASUREMENTS AND MAIN RESULTS

One thousand five hundred and fifty-eight patients received mechanical ventilation at 40 hospitals for asthma: 47 (3%) received VA treatment at 11 (28%) hospitals. Those receiving a VA were significantly less likely to receive inhaled b-agonists, ipratropium bromide, and heliox, but more likely to receive neuromuscular blocking agents than patients treated without VA. Length of mechanical ventilation, hospital stay (length of stay [LOS]) and charges were significantly greater for those treated with VA. Aspiration was more common but death and air leak did not differ. Patients at hospitals with VA use >10% were significantly less likely to receive inhaled b agonist, ipratropium bromide, methylxanthines, and heliox, but more likely to receive systemic b agonist, neuromuscular blocking agents compared to those treated at hospitals not using VA. LOS, duration of ventilation, and hospital charges were significantly greater for patients treated at centers with high VA use.

CONCLUSIONS

Mortality does not differ between centers that use VA or not. Patients treated at centers with high VA use had significantly increased hospital charges and increased LOS.

Update on perioperative management of the child with asthma

Asthma represents the leading cause of morbidity from a chronic disease among children. Dealing with this disease during the perioperative period of pediatric surgical procedures is, therefore, quite common for the anesthesiologist and other professionalities involved. Preoperative assessment has a key role in detecting children at increased risk of perioperative respiratory complications. For children without an optimal control of symptoms or with a recent respiratory tract infection elective surgery should be postponed, if possible, after the optimization of therapy. According to clinical setting, loco-regional anesthesia represents the desirable option since it allows to avoid airway instrumentation. Airway management goals are preventing the increase of airflow resistance during general anesthesia along with avoiding triggers of bronchospasm. When their use is possible, face mask ventilation and laringeal mask are considered more reliable than tracheal intubation for children with asthma. Sevoflurane is the most commonly used anesthetic for induction and manteinance. Salbutamol seems to be useful in preventing airflow resistance rise after endotracheal intubation. Mechanical ventilation should be tailored according to pathophysiology of asthma: an adequate expiratory time should be setted in order to avoid a positive end-expiratory pressure due to expiratory airflow obstruction. Pain should be prevented and promptly controlled with a loco-regional anesthesia technique when it is possible. Potential allergic reactions to drugs or latex should always be considered during the whole perioperative period. Creating a serene atmosphere should be adopted as an important component of interventions in order to guarantee the best care to the asthmatic child.

Risk assessment for respiratory complications in paediatric anaesthesia: a prospective cohort study

BACKGROUND

Perioperative respiratory adverse events in children are one of the major causes of morbidity and mortality during paediatric anaesthesia. We aimed to identify associations between family history, anaesthesia management, and occurrence of perioperative respiratory adverse events.

METHODS

We prospectively included all children who had general anaesthesia for surgical or medical interventions, elective or urgent procedures at Princess Margaret Hospital for Children, Perth, Australia, from Feb 1, 2007, to Jan 31, 2008. On the day of surgery, anaesthetists in charge of paediatric patients completed an adapted version of the International Study Group for Asthma and Allergies in Childhood questionnaire. We collected data on family medical history of asthma, atopy, allergy, upper respiratory tract infection, and passive smoking. Anaesthesia management and all perioperative respiratory adverse events were recorded.

FINDINGS

9297 questionnaires were available for analysis. A positive respiratory history (nocturnal dry cough, wheezing during exercise, wheezing more than three times in the past 12 months, or a history of present or past eczema) was associated with an increased risk for bronchospasm (relative risk [RR] 8.46, 95% CI 6.18-11.59; p<0.0001), laryngospasm (4.13, 3.37-5.08; p<0.0001), and perioperative cough, desaturation, or airway obstruction (3.05, 2.76-3.37; p<0.0001). Upper respiratory tract infection was associated with an increased risk for perioperative respiratory adverse events only when symptoms were present (RR 2.05, 95% CI 1.82-2.31; p<0.0001) or less than 2 weeks before the procedure (2.34, 2.07-2.66; p<0.0001), whereas symptoms of upper respiratory tract infection 2-4 weeks before the procedure significantly lowered the incidence of perioperative respiratory adverse events (0.66, 0.53-0.81; p<0.0001). A history of at least two family members having asthma, atopy, or smoking increased the risk for perioperative respiratory adverse events (all p<0.0001). Risk was lower with intravenous induction compared with inhalational induction (all p<0.0001), inhalational compared with intravenous maintenance of anaesthesia (all p<0.0001), airway management by a specialist paediatric anaesthetist compared with a registrar (all p<0.0001), and use of face mask compared with tracheal intubation (all p<0.0001).

INTERPRETATION

Children at high risk for perioperative respiratory adverse events could be systematically identified at the preanaesthetic assessment and thus can benefit from a specifically targeted anaesthesia management.

FUNDING

Department of Anaesthesia, Princess Margaret Hospital for Children, Swiss Foundation for Grants in Biology and Medicine, and the Voluntary Academic Society Basel.

Forced expiratory flows and volumes in intubated and paralyzed infants and children: normative data up to 5 years of age

Reference equations that express indexes obtained from forced expiratory maneuvers in relation to height and/or other independent variables are lacking for infants and children with artificial airways. The present study was performed to establish normative data of forced expiration by forced deflation in healthy intubated and paralyzed infants and children and to develop prediction equations in relation to height and to ulna length to enable pulmonary assessments in children whose height is difficult to measure. Measurements of forced and passive expiratory maneuvers after inflation to +40 cmH2O inspiratory pressure were prospectively obtained in 100 healthy anesthetized children from 0 to 5 yr of age. Linear regressions of log-transformed forced vital capacity (FVC) and maximum expiratory flow at 25% and 10% FVC (MEF25 and MEF10, respectively) obtained by forced deflation (−40 cmH2O airway opening pressure) and of analogous indexes obtained by passive deflation were used to develop prediction equations from height or ulna length. FVC was significantly dependent on age and height or ulna length. Prediction equations for FVC using height or ulna length were as follows: ln(FVC in ml) = −5.6 + 2.8 × ln(height in cm) and ln(FVC in ml) = 0.46 + 2.5 × ln(ulna length in cm). Younger subjects had a significantly steeper slope for FVC vs. height than the older age group. Normal reference data for forced expiratory maneuvers in intubated infants and children up to 5 yr of age will enable improved assessment of pulmonary dysfunction in acutely or chronically ventilator-dependent children. Using ulna length instead of height should facilitate respiratory assessment in ventilated children with spinal or joint deformities.

Pediatric anesthesia and recent developments in asthma in children

Asthma is a chronic inflammatory disease and the physiological consequence is bronchial hyperresponsiveness to different stimuli. With the worldwide increase in the prevalence of asthma, an increased number of asthmatics are likely to require anesthesia for surgical procedures. Recent investigations described the role played by different environmental agents in asthma, and clarified assessment and management strategies which can be applied to anesthesia in order to decrease the morbidity related to perioperative bronchospasm in children with asthma.

Asthma, sedation, and the podiatric patient

Propofol is a common drug used for anesthetic induction of patients undergoing surgery. This popular drug has been around for many years and has been subjected to changes in formulation from its original patented formula. Once touted as safe, the newer propofol may possess hidden dangers, particularly for individuals suffering with hyperreactive airway disease.

Halothane, an effective infrequently used drug, in the treatment of pediatric status asthmaticus: a case report

Asthma is the most common chronic disease of childhood. Despite a better understanding of the disease process and its management, status asthmaticus continues to be a life-threatening event. The use of volatile inhaled anesthetics is infrequently reported as adjunctive therapy to conventional treatment of this condition. We report the use of halothane in a mechanically ventilated pediatric patient with life-threatening status asthmaticus who was admitted to the pediatric intensive care unit (PICU) after failing to respond to standard medical therapy and noninvasive positive pressure ventilation. A 12-year-old African American male was seen in the emergency department and treated with intravenous corticosteroids, beta-agonist therapy. He deteriorated rapidly and required endotracheal intubation and mechanical ventilation. Two hours later, the patient developed an acute, severe respiratory acidosis (pH=6.97, PaCO2=171, PaO2=162, BE=1.7). Halothane was started at 2% by using the Siemens Servo 900C anesthesia ventilator. Improvement in both arterial blood gases and exhaled tidal volume were noted 30 minutes after initiation of the anesthetic gas. The patient remained on halothane for a total of 36 hours. No adverse effects associated with the use of halothane were noted. The patient was extubated to BiPAP 16/6, FiO2=0.30 at 68 hours and was discharged home 5 days later.

[Children with bronchial hyperreactivity: is it a problem for the anaesthetist?]

Identification of the patients with hyperreactivity and understanding the underlying physiopathological mechanisms are crucial to prevent the occurrence of peri-operative respiratory adverse events in these patients. Preoperative assessment and preparation is based on the maintenance of any long-term anti-inflammatory treatment, especially the inhaled steroids. Furthermore, premedication is based on the administration of a beta2-agonist, antihistamine and anticholinergic drugs that are able to prevent against lung constriction induced by either vagal stimuli or endogenous mediators such as histamine. Anaesthesia management is primarily based on the use of inhalation agents and especially, isoflurane, which has both a protective and a potent bronchodilation effect.

Early airway infection, inflammation, and lung function in cystic fibrosis

AIMS

To determine the relation between lower airway infection and inflammation, respiratory symptoms, and lung function in infants and young children with cystic fibrosis (CF).

METHODS

A prospective study of children with CF aged younger than 3 years, diagnosed by a newborn screening programme. All were clinically stable and had testing as outpatients. Subjects underwent bronchial lavage (BL) and lung function testing by the raised volume rapid thoracoabdominal compression technique under general anaesthesia. BL fluid was cultured and analysed for neutrophil count, interleukin 8, and neutrophil elastase. Lung function was assessed by forced expiratory volume in 0.5, 0.75, and 1 second.

RESULTS

Thirty six children with CF were tested on 54 occasions. Lower airway infection shown by BL was associated with a 10% reduction in FEV(0.5) compared with subjects without infection. No relation was identified between airway inflammation and lung function. Daily moist cough within the week before testing was reported on 20/54 occasions, but in only seven (35%) was infection detected. Independent of either infection status or airway inflammation, those with daily cough had lower lung function than those without respiratory symptoms at the time of BL (mean adjusted FEV(0.5) 195 ml and 236 ml respectively).

CONCLUSIONS

In young children with CF, both respiratory symptoms and airway infection have independent, additive effects on lung function, unrelated to airway inflammation. Further studies are needed to understand the mechanisms of airway obstruction in these young patients.