PubMed Health⌕ Search

Biomedical subjects

F J Frei

Publications and source records attributed to F J Frei.

At least 19 recordsLinked to original sources
PubMed2006

[Management of the upper airway in spontaneously breathing children. A challenge for the anaesthetist].

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.

Airway Obstruction↗
PubMed2006

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.

Anesthesia, Caudal↗
PubMed2005

[Vascular access in emergency paediatric anaesthesia].

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.

Anesthesia, Intravenous↗
PubMed2005

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.

Adolescent↗
PubMed2005

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.

Bronchoscopy↗
PubMed2002

Perioperative management of a child with very-long-chain acyl-coenzyme A dehydrogenase deficiency.

Very-long-chain acyl-coenzyme A dehydrogenase deficiency is an inborn error of fatty acid metabolism. The clinical presentation of this disease in children is either a severe form with onset of symptoms in the first months of life, cardiomyopathy, metabolic acidosis, myopathy and a high mortality, or a less severe form manifesting mainly with hypoglycaemia. Perioperative fasting and (even emotional) stress can trigger metabolic decompensation through the altered metabolism of endogenous fatty acids resulting in hypoglycaemia, acute cardiac and hepatic dysfunction and rhabdomyolysis. We report the perioperative management of a 9-year-old boy suffering from the severe form of this disease who underwent circumcision. Metabolism was kept stable in this child by using a glucose--electrolyte infusion throughout the perioperative period to avoid the biochemical consequences of fasting and a benzodiazepine--opioid technique combined with regional anaesthesia to minimize the stress response. Considering reports about a possible interference of propofol with fatty acid oxidation and to avoid the unnecessary administration of fatty acids, propofol should not be used in these patients.

Anesthesia, Conduction↗
PubMed2001

[The use of cuffed endotracheal tubes in infants and small children].

The use of endotracheal tubes with a cuff is controversial in infants and small children. Often anaesthetists advocate extreme opinions and whereas some propagate the use of cuffed tubes in all cases without restriction, others condemn their use in infants and small children under all circumstances. In this article, the discussion concerning the use of cuffed endotracheal tubes in infants and small children is based on current data and arguments. Relevant facts about the anatomy of the upper airway are reviewed and tube products that are currently available, their correct use in infants as well as the inherent potential advantages and disadvantages related to their use are discussed. The overall incidence of iatrogenic damage after short lasting endotracheal intubation is low. However, acquired subglottic stenosis might represent a severe long-lasting complication. Regardless as to whether tubes with or without cuffs are used, a disproportion between the outer diameter of the tube and the inner diameter of the nonexpandable cricoid ring is the main reason for the genesis of this lesion. A continuous monitoring of the cuff pressure is recommended when using cuffed endotracheal tubes in this age group.

Anesthesia, Inhalation↗
PubMed2001

Similar haemodynamic, respiratory and metabolic changes with the use of sevoflurane or halothane in children breathing spontaneously via a laryngeal mask airway.

BACKGROUND: In preschool children, short-lasting surgical procedures are often performed under combined inhalational and regional anaesthesia with the child breathing spontaneously via a laryngeal mask airway (LMA). Despite widespread use, only limited data are available on haemodynamic, respiratory and metabolic effects of sevoflurane and halothane during LMA anaesthesia. METHODS: In an open-label, randomised, controlled study, 49 children (aged 3-8 years) were allocated to receive either sevoflurane or halothane in 60% nitrous oxide. After insertion of the LMA, end-tidal concentrations of sevoflurane or halothane were maintained at 1 MAC with the child ventilating spontaneously throughout the entire procedure. Analgesia was provided by caudal block. Haemodynamic and respiratory parameters were recorded, and capillary blood-gas samples were obtained repeatedly. RESULTS: Changes in heart rate (HR) and systolic blood pressure were similar in both groups during all observed periods, apart from a significantly higher increase in HR during inhalational induction with sevoflurane (P<0.05). Regression slope analysis during anaesthesia revealed a decrease of the respiratory rate of 5 breaths h-1 (P<0.001) and an increase of end-tidal PCO2 and capillary PCO2 of about 0.25 kPa h-1 (P<0.001), with no significant difference between the two groups. Base excess, calculated in capillary blood gas samples, did not change over time (P>0.5) in either group. CONCLUSIONS: The use of approximately 1 MAC sevoflurane or halothane in 60% N2O in children breathing spontaneously via LMA resulted in comparable haemodynamic, respiratory and metabolic changes, and clinically relevant deteriorations did not occur during the 65-min study period.

Anesthesia, Inhalation↗
PubMed2001

Effect of jaw-thrust and continuous positive airway pressure on tidal breathing in deeply sedated infants.

OBJECTIVES: To examine the physiologic impact of the jaw-thrust maneuver or the administration of continuous positive airway pressure (CPAP) on tidal breathing in deeply sedated infants. STUDY DESIGN: Prospective, non-randomized study of infants undergoing elective fiberoptic bronchoscopy while sedated with intermittent doses of propofol. METHODS: Spontaneous tidal breathing was measured in the supine position by means of a spirometer attached to a bronchoscopy face mask. Tidal breaths were recorded under the following conditions: (1) neutral sniffing position, (2) jaw-thrust, (3) neutral sniffing position, and (4) CPAP of 5 cm H(2)O. Improvement was defined as a change of more than twice the coefficient of variation of repeated measurements of tidal volume and flows from baseline. RESULTS: Jaw-thrust increased tidal volume, minute ventilation, and peak tidal inspiratory and expiratory flows significantly in all 13 infants studied (mean +/- SEM age = 8 +/- 2 months). CPAP increased peak tidal inspiratory and expiratory flows by more than twice the coefficient of variation of baseline measurements in 6 patients and tidal volume and minute ventilation in 5 of 10 patients studied. CONCLUSION: Jaw-thrust and CPAP are effective techniques to improve ventilation of sedated infants undergoing interventions that compromise upper airway patency.

Bronchoscopy↗
PubMed2001

Effect of common airway manoeuvres on upper airway dimensions and clinical signs in anaesthetized, spontaneously breathing children.

Chin lift, jaw thrust and these manoeuvres combined with continuous positive airway pressure (CPAP) can be used to improve the patency of the upper airway during general anaesthesia. We used video endoscopy and measurement of stridor to compare the efficacy of these manoeuvres in 24 children (3-10 yr) with adenotonsillar hyperplasia. A bronchofibrescope was passed via the nose while the children were breathing spontaneously, to identify (i) the shortest transverse distance between the tonsils during inspiration and during expiration and (ii) the distance from the tip of the epiglottis to the posterior pharyngeal wall. Chin lift or jaw thrust lifted the epiglottis and, when combined with CPAP (10 cm H2O), there was a significant lateral displacement of the tonsils. Both chin lift plus CPAP and jaw thrust plus CPAP reduced stridor significantly compared with the unsupported condition. In conclusion, in spontaneously breathing children with large tonsils, chin lift plus CPAP is recommended, whereas jaw thrust plus CPAP is no better and may cause post-operative discomfort.

Adenoidectomy↗
PubMed2001

Effect of airway opening manoeuvres on thoraco-abdominal asynchrony in anaesthetized children.

Thoraco-abdominal asynchrony is frequently encountered during inhalation anaesthesia in children with adenotonsillar hypertrophy causing an upper airway obstruction. The study goal was to evaluate the impact of different airway opening manoeuvres on thoraco-abdominal asynchrony as a measure of airway obstruction. Thirty anaesthetized children (aged 2-8 yrs; sevoflurane 3% in 50% oxygen/nitrous oxide) were studied prior to elective adenotonsillectomy using respiratory inductance plethysmography to record ribeage and abdominal wave forms as a basis for calculation of the phase angle. Five airway situations were compared: 1) baseline (unsupported mandible); 2) chin lift; 3) chin lift combined with continuous positive airway pressure of 10 cmH2O; 4) jaw thrust; and 5) jaw thrust combined with continuous positive airway pressure of 10 cmH2O. Three children had complete upper airway obstruction at baseline and were excluded from the study. With chin lift, thoraco-abdominal asynchrony improved in three patients, worsened in three patients and was unchanged in 21 patients. Additional continuous positive airway pressure during chin lift did not markedly reduce thoraco-abdominal asynchrony (phase angle 89 +/- 43 , p = 0.33). Jaw thrust resulted in a significant decrease of the phase angle (from 106 +/- 53 at baseline to 65 +/- 49 , p < 0.01); when combined with continuous positive airway pressure, no further effect on thoraco-abdominal asynchrony was found (72 +/- 44). In anaesthetized children with adenotonsillar hypertrophy, airway opening manoeuvres have distinct effects on thoraco-abdominal asynchrony. Delivery of continuous positive airway pressure and jaw thrust can be the first airway opening manoeuvres to improve breathing patterns. Chin lift without additional continuous positive airway pressure should be used with caution in these patients because it may convert partial into almost complete airway obstruction.

Adenoidectomy↗
PubMed2000

Increased withdrawal volume per deposit for pre-operative autologous blood donation in adolescents.

OBJECTIVES: This study was undertaken to assess the feasibility, tolerance, haemodynamic and haematologic effects of an aggressive phlebotomy schedule for autologous blood donation (ABD) in adolescents undergoing major orthopaedic surgery. METHODS: Twenty adolescents were studied prospectively; 10 patients in group A donated 20% of the circulating blood volume on 2 occasions, whereas 10 patients in group B donated 10% on 4 occasions. RESULTS: The amount of blood donated, subjective tolerance, cardiovascular changes during the procedure and pre-operative haemoglobin level did not differ between the study groups (group A 111+/-16 vs. group B 106+/-10 g/l). The increase in erythropoietin was greater and occurred sooner in group A than in group B. CONCLUSION: In adolescents ABD is feasible with a reduced number of appointments as they demonstrate tolerance to phlebotomies with a volume which is double the standard per deposit.

Adolescent↗
PubMed1999

Airway obstruction due to arytenoid prolapse in a child.

In paediatric patients, obstruction of the upper airway is still a common problem during general anaesthesia. This case report documents the susceptibility of arytenoids to prolapse in paediatric patients during halothane anaesthesia. The use of video endoscopy provides an excellent tool for visualizing this type of airway obstruction; and continuous positive airway pressure is an effective treatment for clearing the airway.

Airway Obstruction↗
PubMed1999

Effect of combined mouth closure and chin lift on upper airway dimensions during routine magnetic resonance imaging in pediatric patients sedated with propofol.

BACKGROUND: In pediatric patients, obstruction of the upper airway is a common problem during general anesthesia. Chin lift is a commonly used technique to improve upper airway patency. However, little is known about the mechanism underlying this technique. METHODS: The authors studied the effect of the chin lift maneuver on airway dimensions in 10 spontaneously breathing children (aged 2-11 yr) sedated with propofol during routine magnetic resonance imaging. The minimal anteroposterior and corresponding transverse diameters of the pharynx were determined at the levels of the soft palate, dorsum of the tongue, and tip of the epiglottis before and during the chin lift maneuver. Additionally, cross-sectional areas were calculated at these sites, including tracheal areas 2 cm below the glottic level. RESULTS: Minimal anteroposterior diameter of the pharynx increased significantly during chin lift at all three levels in all patients. The diameters of the soft palate, tongue, and epiglottis increased from 6.7+/-2.8 mm (SD) to 9.9+/-3.6 mm, from 9.6+/-3.6 mm to 16.5+/-3.1 mm, and from 4.6+/-2.5 mm to 13.1+/-2.8 mm, respectively. The corresponding transverse diameter of the pharynx also increased significantly at all three levels in all patients but without significant predominance. The diameters at the levels of the soft palate, tongue, and epiglottis increased from 15.8+/-5.1 mm to 22.8+/-4.5 mm, from 13.5+/-4.9 mm to 18.7+/-5.3 mm, and from 17.2+/-3.9 mm to 21.2+/-3.7 mm, respectively. Cross-sectional pharyngeal areas increased significantly at all levels (soft palate, from 0.88+/-0.58 cm2 to 1.79+/-0.82 cm2; tongue, from 1.15+/-0.45 cm2 to 2.99+/-1.30 cm2; epiglottis, from 1.17+/-0.70 cm2 to 3.04+/-0.99 cm2), including the subglottic level (from 0.44+/-0.15 cm2 to 0.50+/-0.14 cm2). CONCLUSIONS: This study shows that all children had a preserved upper airway at all measured sites during propofol sedation. Chin lift caused a widening of the entire pharyngeal airway that was most pronounced between the tip of the epiglottis and the posterior pharyngeal wall. In pediatric patients, chin lift may be used as a standard procedure during propofol sedation.

Child↗
PubMed1999

Fibreoptic bronchoscopy in sedated infants facilitated by an airway endoscopy mask.

Fibreoptic bronchoscopy (FB) is frequently associated with a decline in PaO2, whose degree and duration can be substantial especially in infants. The effect of a face mask, which allows the administration of 100% oxygen and continuous positive airway pressure during FB, on the incidence and severity of hypoxaemia was studied in thirty-one consecutive infants. Sedation was provided by intravenous propofol titrated to allow patient comfort. A transient fall in SpO2 <95% was recorded in 6/31 patients during endoscopy of the upper airway (lasting 1.6+/-1.1 min) and in 11/31 patients during endoscopy of the lower airways (lasting 1.4+/-1.1 min). Capillary blood gas analysis before and after endoscopy of the lower airways demonstrated an increase in the PCO2 6.4+/-1.3 to 7.3+/-1.4 kPa (49+/-10 to 56+/-11 mmHg). The risk of hypoxaemia in sedated infants breathing spontaneously is low when 100% oxygen and continuous positive airway pressure are administered during FB

Blood Pressure↗