[Avoidance of complications when dealing with central venous catheters in the treatment of children]. / Vermeidung von Komplikationen im Umgang mit zentralen Venenkathetern bei Kindern.

Central venous catheters (CVCs) are an important tool in the treatment of children. The insertion of a catheter may result in different complications depending of the type of catheter, the technique used for the insertion and the location. There are various techniques to reduce the risk of complications. In order to reduce the rate of complications of CVCs it is indispensable to perform a risk-benefit analysis for the individual patient before every insertion. The type of catheter used (for example tunneled catheters versus not-tunneled catheters) influences the rate of catheter-associated infections and the comfort of the patient significantly. The choice of the location is influenced by the expected indwelling time, the weight of the patient and the purpose of the CVC. Insertion via the vena jugularis interna is often chosen because of the reduced rate of complications during insertion. When the planned indwelling time of the catheter is longer or the child is fairly small the vena subclavia appears to be more appropriate. It is of utmost importance that the patient is positioned properly before insertion. Whenever possible the insertion should be performed with the help of ultrasound. The positioning of the catheter should be verified radiographically, possibly sonographically or with an ECG in order to avoid misplacement with potentially severe sequelae. The locally established hygienic guidelines should be strictly adhered to and everyone handling CVCs (doctors, nurses and patients) should have regular training.

Effects of anaesthesia on paediatric lung function.

Respiratory adverse events are one of the major causes of morbidity and mortality in paediatric anaesthesia. Aside from predisposing conditions associated with an increased risk of respiratory incidents in children such as concurrent infections and chronic airway irritation, there are adverse respiratory events directly attributable to the impact of anaesthesia on the respiratory system. Anaesthesia can negatively affect respiratory drive, ventilation/perfusion (V/Q) matching and tidal breathing, all resulting in potentially devastating hypoxaemia. Understanding paediatric respiratory physiology and its changes during anaesthesia will enable anaesthetists to anticipate, recognize and prevent deterioration that can lead to respiratory failure. This review aims to give a comprehensive overview of the effects of anaesthesia on respiration in children. It focuses on the impact of the different components of anaesthesia, patient positioning and procedure-related changes on respiratory physiology.

The effect of intravenous lidocaine on laryngeal and respiratory reflex responses in anaesthetised children*.

We studied the effect of intravenous lidocaine on laryngeal and respiratory reflex responses in children anaesthetised with sevoflurane. We tested the hypothesis that the incidence of laryngospasm evoked by laryngeal stimulation is temporarily diminished after the administration of lidocaine. Forty children, aged between 25 and 84months, were anaesthetised with sevoflurane and breathed spontaneously through a laryngeal mask airway. Respiratory reflex responses were elicited by spraying distilled water onto the laryngeal mucosa at three time intervals: (i) before lidocaine was administered (baseline); (ii) at 2min and (iii) at 10min following the intravenous administration of a bolus of lidocaine 2mg.kg(-1) . A blinded reviewer assessed the evoked responses. The incidence of laryngospasm was reduced from 38% at baseline to 15% 2min after lidocaine administration (p<0.02) and 18% 10min after lidocaine administration (p=0.10). We conclude that intravenous lidocaine significantly reduced the incidence of laryngospasm but that the effect was short-lived.

Computed tomography changes of alveoli and airway collapse after laryngospasm.

An eight-month-old girl underwent a computed axial tomographic study of the chest and neck for investigation of expiratory stridor. Following the scout scan, severe laryngospasm developed. While no cause for the laryngospasm was found, the computed axial tomographic chest study showed marked changes in the lungs consistent with absorption atelectasis which we postulate occurred secondary to laryngospasm.

Fibreoptic assessment of paediatric sized laryngeal mask airways.

Laryngeal mask airways (LMA) are commonly used in paediatric anaesthesia. A well-placed LMA should provide a direct view of the vocal cords facilitating bronchoscopy or fibreoptic intubation. The aim of this audit was to assess the bronchoscopic view of the glottis obtained through an LMA with regard to its size. We prospectively assessed the position of LMAs in relation to the glottic aperture in 350 children (zero to seven years) undergoing elective fibreoptic examination of the upper and/or lower airways. Following induction of anaesthesia and positioning of the LMA, a fibreoptic evaluation of the view of the glottis was performed (complete, partial or no visualisation). Chest movement on manual ventilation was judged as good in the majority of patients and adequate for the remainder. No overt signs of airway obstruction were noted in any patient. However, a complete view of the glottic aperture was present in only 50% of size 1 LMAs, 57.5% of size 1.5, 72.7% of size 2 and 77.8% of size 2.5. The epiglottis impinged on the LMA opening, partially obstructing the view of the glottis in 36.3% of size 1 LMAs, 31.5% of size 1.5, 21% of size 2 and 17.8% of size 2.5. In 13.7% of size 1 LMAs, 11% of size 1.5, 6.3% of size 2 and 4.4% of size 2.5, the epiglottis was completely downfolded, obstructing the view of the glottic aperture. The findings indicate that even if ventilation is judged as adequate, smaller paediatric LMAs are more commonly associated with suboptimal anatomical positioning with partial obstruction of the glottic aperture than larger LMAs, and therefore may require repositioning more often.

[Paediatric simulation today and tomorrow. Perspectives and concepts]. / Kindersimulation heute und morgen. Perspektiven und Konzepte.

The confrontation with critically ill newborns, infants and small children is rare and poses a particular challenge for the medical team. Confident technical and non-technical skills are essential for successful emergency treatment. Paediatric simulators facilitate a didactic infrastructure, linking textbook theory with experience-based practice. To summarize the current status of paediatric simulation in Germany, Austria and Switzerland an online survey of all associated centres was conducted. Paediatric simulation is currently available at 24 centres, which have 39 paediatric simulators available, including 8 for newborns, 26 for infants and 5 for children. A certain congruence of standards is detectable among these centres and most instructors have completed a specialized instructor training. Of the instructors 26% are specialized nursing personnel and 67% are physicians of which most are paediatricians and anaesthesiologists. Many centres (38%) operate solely by means of the enthusiastic dedication of the employees who organize various activities during their free time. Nearly all centres (92%) place particular emphasis on non-technical skills which include the interpersonal aspects of crisis resource management. Video-supported debriefing is considered to be the basis for effective training. Within the scope of the recently established PaedSim project the curricula of paediatric simulation courses should be more structured and internationally standardized, thereby increasing both efficacy and sustainability of these training programs.

Pressure volume curves of paediatric laryngeal mask airways.

Hyperinflation of the laryngeal mask airway cuff may exert high pressure on pharyngeal and laryngeal structures. In vitro data show that high intra cuff pressures may occur when inflated to only 30% of the manufacturer's recommended maximum inflation volume. We prospectively assessed the pressure volume curves of paediatric sized laryngeal mask airways (size 1-3) in 240 consecutive children (0-15 years). Following laryngeal mask airway insertion the cuff was inflated with 1-ml increments of air up to the maximum recommended by the manufacturer. After each ml cuff pressure was measured. At the end all cuff pressures were adjusted to 55 cmH(2)O. The maximum recommended volume resulted in high intracuff pressures in all laryngeal mask airway brands and sizes studied. Approximately half the maximum volume produced a cuff pressure > or = 60 cmH(2)O. This occurred in all brands and all sizes studied. We recommend that cuff manometers should be used to guide inflation in paediatric laryngeal mask airways.

Laryngeal mask airway and tracheal tube cuff pressures in children: are clinical endpoints valuable for guiding inflation?

We prospectively assessed common clinical endpoints for their usefulness in avoiding hyperinflation of the cuffs of laryngeal mask airways (slight outward movement) and tracheal tubes (disappearance of an audible leak around the cuff during manual ventilation < 20 cm H(2)O) in 640 children. Cuff pressures were measured at induction and immediately before emergence from anaesthesia. With the laryngeal mask airway (sizes 1-4), the median cuff pressures ranged from 90 to > 120 cm H(2)O at induction and 105 to > 120 cm H(2)O before emergence. With tracheal tubes (sizes 3-7 mm), median cuff pressures were 40-60 cm H(2)O at induction and 45-70 cm H(2)O at emergence. With the use of nitrous oxide a consistent rise in cuff pressure was observed between the first and second readings whereas cuff pressures remained constant when nitrous oxide was not used. The use of clinical endpoints alone was associated with significant hyperinflation of cuffs with both devices in almost all patients, with an exacerbation when nitrous oxide was used. In order to avoid unnecessary cuff hyperinflation in laryngeal mask airways and tracheal tubes, the routine use of cuff manometers is mandatory in children.

Evaluation of cast wedging in a forearm fracture model.

BACKGROUND: In paediatric traumatology fractures are commonly treated with a cast. In this course cast wedging is sometimes performed aiming to reduce the fracture angulation. However, the impact of various factors and measures such as cast material, optimal position of the wedge and wrist position were not assessed in a systematic manner. METHODS: A laser supported model was developed to evaluate the biomechanical processes of cast wedging manoeuvre in a model of a distal diaphyseal forearm fracture. Consecutive measurements were performed to find out the influence of wedge position, cast material and wrist position. FINDINGS: The result of the manoeuvre was revealed to be independent of the cast material (plaster of Paris vs. synthetic cast) used. The optimal position for placing the wedge was shown to be on the concave side of the cast at the level of the fracture. The result of a cast wedging manoeuvre in a dorsally displaced forearm fracture can be optimized with the wrist held in extension. INTERPRETATION: The cast wedging model is not a meticulous copy of the human anatomy but it allows some basic studies on cast wedging technique. The results that can be achieved are similar to the experiences of practical paediatric traumatology. Furthermore the present model may be beneficial for use in education and training programs.

The impact of head position on the cuff and tube tip position of preformed oral tracheal tubes in young children.

Head and neck movements affect both the length of the trachea and the position of tracheal tubes. This is of relevance when using cuffed tubes because changes in the position of the tube tip may not be equal to changes in the position of the cuff. The aim of the study was to assess the impact of head and neck movement on the position of the tube tip and the cuff of newly designed, oral preformed tracheal tubes in children. The tracheas of 128 children aged 1-8 years were intubated with preformed oral tubes. The distances 'carina-to-tracheal tube tip' and 'vocal cords-to-tube tip' were measured endoscopically. These measurements were performed with the head and neck in a functional neutral position (110 degrees ), during neck flexion (80 degrees ) and neck extension (130 degrees ). Tracheal length was dependent on head and neck position: neck extension elongated the trachea (p < 0.0001), and neck flexion shortened the trachea (p < 0.0001). Neck flexion moved the tube inward and resulted in endobronchial displacement in two patients. Neck extension moved the tube outwards. While no cuff was positioned between the vocal cords, cuff movement to the cricoid area occurred frequently. Complex interactions during head and neck movement along with the fixed insertion depth of preformed tubes often cause inadvertent malpositioning of the tube tip and cuff. Further changes to tube and cuff lengths might improve the safety of oral preformed tubes in children.

Impact of Trendelenburg positioning on functional residual capacity and ventilation homogeneity in anaesthetised children.

Trendelenburg positioning, a head-down tilt, is routinely used in anaesthesia when inserting a central venous catheter to increase the calibre of the jugular or subclavian veins and to prevent an air embolism. We investigated the impact of Trendelenburg positioning on functional residual capacity and ventilation homogeneity as well as the potential reversibility of these changes by repositioning and/or a recruitment manoeuvre in children with congenital heart disease. Functional residual capacity and ventilation homogeneity were assessed in 20 anaesthetised children between the ages of 3 months and 8 years who required central venous catheterisation before undergoing cardiac surgery. Functional residual capacity was measured (1) in the supine position, (2) in the Trendelenburg position, (3) after repositioning supine and (4) after a recruitment manoeuvre to total lung capacity which was performed by manually elevating the airway pressure to 40 cmH(2)O for ten consecutive breaths. Adopting the Trendelenburg position led to a significant decrease in functional residual capacity (median [range]- 12 (6-21)%) and increase in lung clearance index (12 (2-19)%). Baseline values were not reached after repositioning supine in any patient until after a standardised recruitment manoeuvre was performed.

Impact of depth of propofol anaesthesia on functional residual capacity and ventilation distribution in healthy preschool children.

BACKGROUND: Propofol is commonly used in children undergoing diagnostic interventions under anaesthesia or deep sedation. Because hypoxaemia is the most common cause of critical deterioration during anaesthesia and sedation, improved understanding of the effects of anaesthetics on pulmonary function is essential. The aim of this study was to determine the effect of different levels of propofol anaesthesia on functional residual capacity (FRC) and ventilation distribution. METHODS: In 20 children without cardiopulmonary disease mean age (SD) 49.75 (13.3) months and mean weight (SD) 17.5 (3.9) kg, anaesthesia was induced by a bolus of i.v. propofol 2 mg kg(-1) followed by an infusion of propofol 120 microg kg(-1) min(-1) (level I). Then, a bolus of propofol 1 mg kg(-1) was given followed by a propofol infusion at 240 microg kg(-1) min(-1) (level II). FRC and lung clearance index (LCI) were calculated at each level of anaesthesia using multibreath analysis. RESULTS: The FRC mean (SD) decreased from 20.7 (3.3) ml kg(-1) at anaesthesia level I to 17.7 (3.9) ml kg(-1) at level II (P < 0.0001). At the same time, mean (SD) LCI increased from 10.4 (1.1) to 11.9 (2.2) (P = 0.0038), whereas bispectral index score values decreased from mean (SD) 57.5 (7.2) to 35.5 (5.9) (P < 0.0001). CONCLUSIONS: Propofol elicited a deeper level of anaesthesia that led to a significant decrease of the FRC whereas at the same time the LCI, an index for ventilation distribution, increased indicating an increased vulnerability to hypoxaemia.

The effect of caudal block on functional residual capacity and ventilation homogeneity in healthy children.

Caudal block results in a motor blockade that can reduce abdominal wall tension. This could interact with the balance between chest wall and lung recoil pressure and tension of the diaphragm, which determines the static resting volume of the lung. On this rationale, we hypothesised that caudal block causes an increase in functional residual capacity and ventilation distribution in anaesthetised children. Fifty-two healthy children (15-30 kg, 3-8 years of age) undergoing elective surgery with general anaesthesia and caudal block were studied and randomly allocated to two groups: caudal block or control. Following induction of anaesthesia, the first measurement was obtained in the supine position (baseline). All children were then turned to the left lateral position and patients in the caudal block group received a caudal block with bupivacaine. No intervention took place in the control group. After 15 min in the supine position, the second assessment was performed. Functional residual capacity and parameters of ventilation distribution were calculated by a blinded reviewer. Functional residual capacity was similar at baseline in both groups. In the caudal block group, the capacity increased significantly (p < 0.0001) following caudal block, while in the control group, it remained unchanged. In both groups, parameters of ventilation distribution were consistent with the changes in functional residual capacity. Caudal block resulted in a significant increase in functional residual capacity and improvement in ventilation homogeneity in comparison with the control group. This indicates that caudal block might have a beneficial effect on gas exchange in anaesthetised, spontaneously breathing preschool-aged children with healthy lungs.

[Management of the upper airway in spontaneously breathing children. A challenge for the anaesthetist]. / Management der oberen Atemwege beim spontan atmenden Kind. Eine Herausforderung für den Anästhesisten.

In unconscious, spontaneously breathing and anaesthetised children, a high incidence of partial or complete airway obstruction jeopardizes sufficient oxygenation. In this situation, the most important and efficient manoeuvre is to open up the upper airway. Chin lift, jaw thrust and continuous positive airway pressure (CPAP) are proven and effective methods for opening an obstructed upper airway. In addition to these simple airway manoeuvres, different techniques of body positioning (e.g., lateral positioning or supine position in combination with the "sniffing position") are effective to improve and maintain upper airway patency.

Use of continuous positive airway pressure during flexible bronchoscopy in young children.

Young children are at increased risk for hypoxaemia and hypercapnia during flexible bronchoscopy due to the small size and increased collapsibility of their airways. Various strategies are used to prevent hypoventilation and to provide oxygen during the procedure. The aim of this study was to assess the impact of continuous positive airway pressure (CPAP) on ventilation during flexible bronchoscopy in infants and young children. Tidal breathing was measured in 16 spontaneously breathing and deeply sedated children, aged 3-25 months, by ultrasound spirometry via an airway endoscopy mask. Measurements were made with the tip of the bronchoscope positioned in the pharynx with no CPAP, and in mid-trachea with 0, 5 and 10 cmH2O of CPAP. Transition of the bronchoscope through the vocal cords was associated with significant decreases of tidal volumes (5.0+/-0.5 versus 3.4+/-0.5 mL.kg(-1)), peak tidal expiratory flows (78+/-12 versus 52+/-10 mL.s(-1)) and peak tidal inspiratory flows (98+/-15 versus 66+/-12 mL.kg(-1)). CPAP (5-10 cmH2O) induced almost complete reversal of these changes. In conclusion, it is shown here that flexible bronchoscopy in spontaneously breathing young children is associated with significant decreases in tidal volume and respiratory flow. These changes are largely reversible with continuous positive airway pressure.

Jaw thrust can deteriorate upper airway patency.

Upper airway obstruction is a frequent problem in spontaneously breathing children undergoing anesthesia or sedation procedures. Failure to maintain a patent airway can rapidly result in severe hypoxemia, bradycardia, or asystole, as the oxygen demand of children is high and oxygen reserve is low. We present two children with cervical masses in whom upper airway obstruction exaggerated while the jaw thrust maneuver was applied during induction of anesthesia. This deterioration in airway patency was probably caused by medial displacement of the lateral tumorous tissues which narrowed the pharyngeal airway.

[Vascular access in emergency paediatric anaesthesia]. / Vaskulärer Zugang in der Kindernotfallanästhesie.

There is very little literature to guide the young practitioner in caring for a child that needs emergency surgery and has difficult venous access. Questionnaires were sent to 89 members of the Swiss Paediatric Anaesthesia Society and to the heads of Anaesthesia Departments of Swiss teaching hospitals. Two typical case records were presented, both of which were characterised by the fact that 2-3 peripheral venous cannulation attempts were unsuccessful. Case A: a young child with a fracture of the radius and case B an infant with upper gastrointestinal ileus. The anaesthetists were then questioned regarding their preferences for optimal treatment. The majority would proceed with further attempts and, if these still failed, intramuscular or inhalational induction of anaesthesia was suggested as a reasonable choice for case A. However, for case B, a femoral venous or intraosseous access to the venous system was judged to be the safest method. On the basis of our inquiry and a literature search, a priority list was developed to suggest the best possible techniques for vascular access and alternative anaesthesia induction techniques for emergency paediatric procedures.