Reflection of CO2 laser radiation from laser-resistant endotracheal tubes

To assess the possibility of indirect damage by CO2 laser reflection from specialized or modified tracheal tubes, four different tracheal tubes were studied. They were (1) a Rusch red rubber tracheal tube wrapped with 3M No. 425 aluminum foil tape, (2) a Rusch red rubber tracheal tube wrapped with Venture copper foil tape, (3) a polyvinylchloride tracheal tube wrapped with Laser-Guard protective coating, and (4) a Mallinckrodt Laser-Flex tracheal tube. The tracheal tubes were straightened and centered within cardboard cylinders and the laser set to 40 W was aimed to reflect from the tracheal tubes onto the cardboard. The times to combustion perforating the cardboard cylinders because of laser reflection were 1.41 +/- 0.54 (mean +/- SD), 1.73 +/- 0.93, 3.70 +/- 2.18, and 9.26 +/- 3.40 s for tracheal tubes 1, 2, 3, and 4, respectively. The differences between the times to combustion with tracheal tubes 3 and 1, 3 and 2, 4 and 1, 4 and 2, and finally, 4 and 3 were statistically significant. We conclude that the Laser-Guard-wrapped polyvinylchloride tracheal tube and the Mallinckrodt Laser-Flex tracheal tube were less reflective of incident CO2 laser radiation than the copper or aluminum-foil-wrapped red rubber tracheal tubes.     

Intraoperative scanning laser Doppler flowmetry in the assessment of gastric tube perfusion during esophageal resection

BACKGROUND: Ischemia from tissue hypoperfusion in the gastric tube after esophagectomy is believed to contribute significantly to postoperative complications associated with anastomotic failure. This study assessed the ability of the new technique of laser Doppler flowmetry to measure differential levels of blood flow in human gastric tubes during esophagectomy. STUDY DESIGN: Gastric perfusion was measured in 16 patients undergoing esophagectomy by making laser Doppler scans of the stomach before mobilization and after formation of the gastric tube. Mean perfusion was calculated within the whole anterior surface of the stomach or tube and within 1 cm2 regions of interest, each of which contained 1,750 individual measurements of perfusion. These regions represented the cephalic end of the gastric tube, 10 adjacent 1 cm2 regions distally along the tube, and the proposed anastomosis site. Results were expressed as mean perfusion units, and tissue blood flow from each scan in each region was compared. RESULTS: There were significant decreases in gastric perfusion measured with the scanning laser Doppler in all patients after formation of the gastric tube. Mean perfusion of the stomach fell 41% (p<0.0005) after mobilization. In all patients there was a gradient of perfusion from the proximal end of the tube where flow was poor, to more distal areas where it was higher. At the proximal end of the tube perfusion fell by a mean of 72%, 5 cm distally the mean fall was 44%, and 10 cm from the proximal end of the tube the mean fall was 28%. At the anastomosis site mean perfusion fell 55%. CONCLUSIONS: This new technique can be used intraoperatively and appears to overcome the limitations of single point laser Doppler flowmetry. It has measured large differences in perfusion at different sites within the gastric tubes and could therefore have widespread clinical applications.     

Fiberoptisch unterstützte endotracheale Intubation durch die Larynxmaske im Kindesalter

Fibre optic-assisted tracheal intubation through the laryngeal mask airway is a simple and safe procedure for securing the airway in the paediatric patient with unexpected and known difficult tracheal intubation. Therefore, fibre optic-assisted tracheal intubation through the laryngeal mask airway represents a standard airway technique and must be part of clinical education and also regular training. However, the removal of the laryngeal mask airway over the tracheal tube is impaired by the short length of the tracheal tube, easily resulting in tube dislocation from the trachea. Among several techniques to overcome this problem, the Cook airway exchange catheter offers a reliable method not only for safe removal of the laryngeal mask over the tracheal tube but also for insertion of an adequate tracheal tube, particularly in paediatric patients. This is particularly important for cuffed tubes as the pilot balloon of the cuffed tube is too large to pass through laryngeal mask airway tubes size 2.5 and smaller. This presentation demonstrates fibre optic-assisted tracheal intubation through the laryngeal mask airway in children step-by-step and discusses its clinical implications. A list with compatible sizes of laryngeal mask airways, tracheal tubes and airway exchange catheters is also provided.     

Einsatz von gecufften Endotrachealtuben bei Kindern in der Notfall- und Rettungsmedizin

Cuffed pediatric tracheal tubes are increasingly used in pediatric anesthesia and pediatric intensive care for infants and small children. High chance to select a correct-fitting tube and reliable sealing of the trachea without the use of an oversized uncuffed tube are the most import advantages of using cuffed tubes for infants and small children in emergency situations. If cuffed tubes in pediatric emergency are used a well-designed tube with a correctly placed high volume-low pressure and an adequate intubation depth mark and the presence of a printed chart with recommendations for age-related tube size selection should be available. Confirmation of an air leak around the tracheal tube after intubation with the cuff not inflated, cuff inflation by cuff pressure monitoring and limitation of cuff pressure at 20 cmH₂O allows the safe use of cuffed tracheal tubes in infants and children. In case of lack of good pediatric cuffed tubes, lack of a chart with recommendations for age-related tube size selection and lack of a cuff pressure manometer, cuffed pediatric tubes should not be used in infants and children in the emergency setting.     

Inaccuracy of peranesthetic gastric intubation for emptying liquid stomach contents

To assess the accuracy of the method of peranesthetic gastric intubation for emptying the liquid stomach contents, this procedure was tried on 80 patients undergoing general anesthesia. Half of the patients had a double-barrelled 16F-Argyle Salem sump tube, length 120 cm, size 16 CH, and the other half had a single-barrelled stomach tube, length 80 cm, size 25 CH. After emptying the stomach with the tubes 25 ml of glucose was given through the gastric tube to half of the Salem tube group and half of the stomach tube group. Similarly 100 ml of glucose was given to half of the Salem tube group and half of the stomach tube group. After instillation of glucose 25 ml or 100 ml, the Salem tube recovered 21.0 +/- 9.1 ml (mean +/- s.d.), median 24 ml, range 6-36 ml or 86.8 +/- 26.9 ml, median 92 ml, range 18-136 ml, respectively, and the stomach tube 17.1 +/- 10.8 ml, median 18 ml, range 2-34 ml or 54.0 +/- 28.5 ml, median 50 ml, range 14-104 ml, respectively. This indicates that the method of gastric intubation for emptying the liquid stomach contents is inaccurate.     

Motor activity of esophageal substitute (stomach, jejunal, and colon segments)

Manometric studies were performed to evaluate motor activity of several types of esophageal substitutes: total stomach (5 patients), isoperistaltic gastric tube (5 patients), jejunal Roux-en-Y loops (4 patients), and isoperistaltic left colon (15 patients). Motor behavior of substitutes was assessed following dry swallows and following several stimuli: intraluminar injection of 30 ml of water or 0.1N hydrochloric acid and swallowing pills. Following dry swallows, there was no response with either stomach or isoperistaltic gastric tube, jejunum showed a variable response, and a response was infrequent in patients with colon transplants. After dry swallows, transmission of the pressure wave through the anastomosis was not observed in any patient. Total stomach and isoperistaltic gastric tube did not respond to any stimulus. Jejunum responded with progressive waves after water and solid stimuli, and had a hyperkinetic response after acid injection. Colon had a constant (80 to 90%) and homogeneous response with progressive waves after all stimuli. After wet swallows, there was transmission through the anastomosis in 2 patients with colon transplants. Our data indicate that stomach and isoperistaltic gastric tubes do not contribute actively to the onward transmission of food in the digestive tract. Jejunum may contribute actively in digestive transit, but its responses are variable. Having steady and homogeneous responses, colon segments take an active part in transit.     

Two cases of benign tracheo-gastric fistula following esophagectomy for cancer

Two successfully managed cases of esophageal replacement for cancer complicated by neoesophagotracheal fistula are described. In both cases radical esophagectomy with a gastric pull-up was performed. In the postoperative period different complications necessitated prolonged ventilatory support and tracheostomy. In both cases a tracheo-gastric fistula developed probably because of the ischaemic effort of the tracheostomy tube and the nasogastric tube. At single stage repairs, the fistulae were divided and the gastric defects were closed directly. In the first case resection of four strictured tracheal rings and tracheal anastomosis had to be performed. In the second case the fistula was recognized earlier and stricture did not develop. The defect on the membranous trachea was patched with autologous fascia lata graft. A left pectoralis major muscle flap was interposed between the trachea and the pulled up stomach in both cases to prevent recurrence of the fistula. Treatment of this potentially life-threatening and rare condition yielded excellent results.     

Evaluation of a new recommendation for improved cuffed tracheal tube size selection in infants and small children

BACKGROUND: The purpose of this study was to evaluate a new recommendation for tracheal tube size selection using second-generation Microcuff paediatric endotracheal tubes (PETs) with optimized outer diameter (OD) of the distal tube. METHODS: With Ethics Committee approval, patients aged from birth to 5 years, requiring general anaesthesia with orotracheal intubation, were included. Tracheal tube sizes were selected as follows: internal diameter (ID) 3.0 mm, birth (if > or =3 kg) to <6 months; ID 3.5 mm, 6 to <18 months; ID 4.0 mm, 18 months to <3 years; ID 4.5 mm, 3 to <5 years. Tracheal tubes with the cuff not inflated were classified as too large if no air leak was obtained at an airway pressure of < or =20 cmH2O. Post-intubation stridor requiring therapy was noted. RESULTS: Three hundred and fifty children were studied. Nine tracheal tubes (2.6%) were too large and had to be exchanged: in patients requiring tracheal tubes of ID 3.0 mm and 3.5 mm, three and four tracheal tubes, respectively, and, in patients requiring tracheal tubes of ID 4.0 mm and 4.5 mm, one tracheal tube in each group. In three patients (0.9%), post-intubation stridor occurred which required therapy. CONCLUSION: The new recommendation presented for the use of second-generation Microcuff PETs with improved OD to ID ratio allows the selection of cuffed tracheal tubes with larger IDs than previously recommended for small children without increased need for tracheal tube exchange or increased incidence of post-intubation stridor in these age groups.     

Continent Gastric Tube: New Techniques and Long-Term Followup

Purpose

The successful use of stomach for bladder augmentation and substitution is well documented. Gastric tissue has been used more recently to create continent catheterizable tubes. We describe 2 new techniques of gastric tube construction, and report our long-term followup of catheterizable gastric tubes in children and adults undergoing complex urinary tract reconstruction.

Materials and Methods

A retrospective chart review of 6 male and 4 female patients 5 to 43 years old was done. Primary diagnoses included bladder exstrophy, cloacal exstrophy, rhabdomyosarcoma and neurogenic bladder. Five patients underwent gastrocystoplasty with simultaneous creation of a continent gastric tube from the anterior gastric flap. In 2 patients who had undergone previous gastrocystoplasty a continent gastric tube was created from an anterior flap raised from the existing gastric bladder. Isolated gastric tubes were constructed in 3 patients.

Results

Followup ranged from 2 to 9 years (median 3.5). All patients demonstrated easy reliable catheterization. One patient required revision of the proximal end of the tube for incontinence. At followup all tubes were continent. Complications occurred only in flush or protuberant stomas, and resolved after stomal revision with recessed skin flaps.

Conclusions

Several techniques can be used to create a continent gastric tube. Long-term followup reveals reliable catheterization and good continence rates. Recession of the gastric tube stoma with a skin flap prevents peristomal complications.     

Comparison of cuffed and uncuffed preformed oral pediatric tracheal tubes

BACKGROUND: In preformed cuffed tracheal tubes the position of the cuff within the airway is given by its distance to the tube bend placed at the lower teeth. The aim of this study was to compare the design of cuffed and uncuffed preformed pediatric oral tracheal tubes with regard to anatomical landmarks. METHODS: Complete series of cuffed and uncuffed preformed oral pediatric tracheal tubes sized from internal diameter 3.0-7.0 mm if available were ordered from five different manufacturers. The distance from the bend to the distal tube tip and to the upper border of the cuff were measured and compared with anatomical airway landmarks in the developing child. RESULTS: Between cuffed and uncuffed tracheal preformed tubes up to 37 mm differences in the bend-to-tracheal tube tip distances were found for given age groups. Thus uncuffed preformed tracheal tubes were more at risk for inadvertent endobronchial intubation than cuffed preformed tracheal tubes. Comparison of bend-to-upper border of the cuff distances with teeth-to-vocal cord distances calculated from anatomical data revealed that several of the tracheal tube cuffs become positioned within the subglottic larynx or even within the vocal cords when inserted according to the bend. CONCLUSIONS: There is a need for improvement in cuffed preformed pediatric tracheal tubes, namely a standard bend-to-tracheal tube tip distance to allow a safe insertion depth, a short cuff placed on the tube shaft as distally as possible and an intubation depth mark to verify a proper position of the cuff in the trachea.     

High incidence of CO2 laser beam contact with the tracheal tube during operations on the upper airway

Polyvinyl chloride tracheal tubes from 50 consecutive CO2 laser operations of the larynx and trachea were collected after tracheal extubation. In all cases, the helium protocol for laser operations was used, which includes the following: helium in the anesthetic gas mixture at 60% or more during laser resection (FIO2 less than or equal to 0.4); tracheal intubation with plain, unmarked polyvinyl chloride tubes; laser power density less than or equal to 1,992 W/cm2; and laser bursts of less than or equal to 10-second duration. No tracheal tube fires or airway burns occurred. The polyvinyl chloride tubes were examined for marks caused by the laser, and cuffed tubes were tested for cuff viability. Of the 50 tubes examined, 18 were noncuffed and 32 were cuffed. Although most contacts did not penetrate the tubes, 58% of the tubes showed evidence of contact with the laser as a brown mark on the tube or as a cuff leak. Cuffed tubes were more likely to incur laser contact (69%) than noncuffed tubes (39%), a significant difference (p = 0.04). Most of the cuffed tubes that came in contact with the laser sustained damage at the cuff (77%). It was concluded that the risk of tracheal tube contact with a laser beam is at least 1 in 2, that cuffed tubes are more likely to be hit with a laser beam than noncuffed tubes, and that cuffed tubes that are hit usually sustain damage to the cuff. Because no fires occurred in this series despite frequent laser contact with the tube, these data indicate that the helium protocol helps to prevent polyvinyl chloride tube fires.     

An assessment of the ability of impedance respirometry distinguish oesophageal from tracheal intubation

Accidental oesophageal intubation is still an important cause of anaesthetic morbidity and mortality. This study investigated the use of impedance respirometry to determine the position of a tracheal tube. Seventy-nine patients undergoing general anaesthesia requiring tracheal intubation with muscle relaxation were recruited to the study. After pre-oxygenation, tracheal tubes were placed in both the oesophagus and trachea; a breathing system was attached to one tube chosen randomly. A blinded observer was required to correctly identify the position of the tube within six tidal ventilations. The position of every tube connected to the breathing system was correctly identified. The median time to correctly identify tracheal and oesophageal tubes was 3 and 5 s, respectively. The median number of breaths to identify tracheal and oesophageal tubes was two for both groups. Every tube position was identified within the required six breaths. Impedance respirometry is a reliable method for diagnosing tracheal tube position.     

Tracheal tube size in adults undergoing elective surgery – a narrative review

Tracheal tubes are routinely used in adults undergoing elective surgery. The size of the tracheal tube, defined by its internal diameter, is often generically selected according to sex, with 7–7.5 mm and 8–8.5 mm tubes recommended in women and men, respectively. Tracheal diameter in adults is highly variable, being narrowest at the subglottis, and is affected by height and sex. The outer diameter of routinely used tracheal tubes may exceed these dimensions, traumatise the airway and increase the risk of postoperative sore throat and hoarseness. These complications disproportionately affect women and may be mitigated by using smaller tracheal tubes (6–6.5 mm). Patient safety concerns about using small tracheal tubes are based on critical care populations undergoing prolonged periods of tracheal intubation and not patients undergoing elective surgery. The internal diameter of the tube corresponds to its clinical utility. Tracheal tubes as small as 6.0 mm will accommodate routinely used intubation aids, suction devices and slim-line fibreoptic bronchoscopes. Positive pressure ventilation may be performed without increasing the risk of ventilator-induced lung injury or air trapping, even when high minute volumes are required. There is also no demonstrable increased risk of aspiration or cuff pressure damage when using smaller tracheal tubes. Small tracheal tubes may not be safe in all patients, such as those with high secretion loads and airflow limitation. A balanced view of risks and benefits should be taken appropriate to the clinical context, to select the smallest tracheal tube that permits safe peri-operative management.     

Use of gum elastic bougie for tracheal intubation: comparison of different tracheal tubes

BACKGROUND: Gum elastic bougie (GEB) is one of the most useful devices for patients whose tracheas are difficult to intubate during anesthetic induction. But no previous study has evaluated the effects of the types of the tracheal tube. We hypothesized that wire-reinforced tracheal tubes were superior to standard tracheal tubes in the success rate of tracheal intubation when using GEB. We compared these two different types of tracheal tubes in using GEB. METHODS: Forty patients were subjected and randomly allocated into two groups; patients intubated with standard tracheal tubes (Group , n = 20) and those with wire-reinforced tracheal tubes (Group S, n = 20). Measured variables were intubation time defined as elapsed time from mouth opening to removal of GEB from tracheal tube, heart rate (HR), and systolic blood pressure(SBP). We also compared trial times of intubation and pharyngeal or laryngeal bleeding as a minor side effect. RESULTS: Trachea was successfully intubated in the frist attempt in 37 patients (92.5%), and the rest of the patients were all intubated at second trial. Intubation times of Group P and Group S were 41.5 +/- 13.9s and 41.3 +/- 11.1s, respectively. There were no significant differences in HR and SBP between the groups. CONCLUSIONS: The type of tracheal tube would not affect the success rate and time of intubation when using gum elastic bougie.     

Comparison between tracheal tubes for orotracheal fibreoptic intubation

We have compared impingement of the tracheal tube against the larynx using a standard preformed tube, warmed preformed tube or two flexible spiral-wound tracheal tubes with different tip designs, in 100 adult patients undergoing orotracheal fibreoptic intubation under general anaesthesia, in a prospective, randomized study. The rates of impingement were 20 of 30 with the standard tube, 12 of 30 with the warmed standard tube (P = 0.07) and eight of 20 with both spiral tubes. However, impingement with the spiral tubes took longer to overcome if a sharp tipped rather than an obtuse tipped tube was used. Manipulations after impaction led to oesophageal intubation in one patient, and in one patient fibreoptic intubation failed. We conclude that resistance to the tracheal tube occurred frequently when the spiral-wound tubes were used.      

EVIDENCE FOR DYNAMIC PHENOMENA IN RESIDUAL TRACHEAL TUBE BIOFILM

It has been proposed recently that a dynamic physical processoccurring in the tracheal tube might account for the disseminationof bacteria and biofilm fragments into the lungs during mechanicalventilation, and the subsequent development of ventilator-associatedpneumonia. In this study of tracheal tubes from consecutiveadult intensive care patients, biofilms were detected radiographicallyin 45 of 50 tubes, and were found at the lower end of the tubemore often than at the upper end (P < 0.005). In 37 of 50tracheal tubes, the maximum biofilm thickness was equal to orgreater than the0.5 mm required for gas-liquid interaction ina tube with an i.d. of 8.5 mm. In 23 of 50 tubes, wave-likepatterns were found. Five tubes had no biofilm inside the bevelledtip and another six showed evidence of biofilm loss for a greaterdistance from the tip. These observations suggest that the distributionof tracheal tube biofilm is caused at least in part by dynamicphenomena in the tracheal tube. (Br. J. Anaesth. 1993; 70: 22–24)     

Gastric volume and pH in out-patients.

We measured the volume and pH of the gastric content of 21 out-patients and 21 in-patients under general anaesthesia. Gastric tubes were inserted after induction of anaesthesia, and gastric fluids were withdrawn for pH determinations. Gastric volumes were measured by a dilution technique using polyethylene glycol as the indicator and also by measurement of the volume aspirated through a gastrict tube. Out-patients had a mean gastric volume of 69 +/- 17 ml while in-patients had a mean volume of 33 +/- 4 ml. The average gastric pH for the out-patients was 1.8 +/- 0.2 and for the in-patients 2.0 +/- 0.3. Four out-patients had more than 75 ml of gastric fluid of pH less than 2.0. Aspiration through a gastrict tube did not empty the stomach completely and the volume thus obtained gave a falsely low estimate of the gastric volume.     

Organ-preserving resection of the gastroesophageal junction and substitution with a gastric corpus rotation tube: an experimental study

Premalignant lesions of the gastroesophageal junction are treated conservatively or by antireflux surgical procedures. We describe a novel technique that replaces the distal esophagus after resection of the gastroesophageal junction. After resection of the gastroesophageal junction, 16 pigs were divided into two groups. In group 1 (n = 9) the gastroesophageal junction was replaced with a 3 cm wide horizontal gastric corpus tube, pedicled at the lesser curvature. In group 2 (n = 7) the tube was pedicled at the greater curvature. Tube length, volume, and compliance of the gastric remnant and blood flow in the tube (by laser Doppler flowmetry given in perfusion units [PU]) were measured before and after tube formation and 2 weeks postoperatively. Group 1 tubes were 9.5 ±1.5 cm long and group 2 tubes were 8.2 ± 0.7 cm long. Tube formation decreased volume and compliance of the gastric remnant. After tube formation, blood flow at the tip of the tube decreased from 254 PU to 64 ±22 PU (group 1) and 87 ±36 PU (group 2). Volume, compliance, and blood flow returned to baseline values 2 weeks postoperatively. No anastomoric leakage was found on postmortem examination. Horizontal gastric corpus tubes might offer an alternative to replace the distal esophagus and proximal stomach after resection of premalignant lesions of the gastroesophageal junction.     

Saline-filled cuffs help prevent laser-induced polyvinylchloride endotracheal tube fires

To determine whether the filling of tracheal tube cuffs with saline would decrease their combustibility during laser surgery, 20 polyvinylchloride tracheal tubes were studied. The cuffed end of each tracheal tube was inserted into the neck of an empty flask, and the tube and flask were flushed with oxygen for 5 min before cuff inflation. Ten tracheal tubes had their cuffs inflated with air, and 10 were inflated with saline. A Lasersonics LS880 CO2 laser, set to 5 W for five of each of the two types of filled cuffs and to 40 W for the other pair of five tubes, was fired continuously at the cuffs for up to 1 min. No combustion occurred at the 5-W setting. The times to cuff perforation when the laser was set at 5 W were (mean +/- SD) 1.00 +/- 0.83 and 4.21 +/- 3.91 s for the air- and saline-filled cuffs, respectively, a difference that was not statistically significant. The time to deflation of the saline-filled cuff (104.6 +/- 67.5 s) was, however, significantly longer than that of the air-filled cuff (2.59 +/- 1.97 s). When the tracheal tube cuffs were exposed to 40-W laser radiation, the cuff and adjacent tube shaft ignited in all cases when the cuffs were inflated with air, but only in one of five cases when the cuffs were filled with saline (P less than 0.05). The filling of tracheal tube cuffs with saline provides simple, moderately effective partial protection of the cuff of endotracheal tubes during CO2 laser airway surgery.     

Airway protection in children with a full stomach

Recent surveys have reevaluated the risk of aspiration of gastric content during anesthesia in pediatric patients. Emergency, bowel obstruction and inadequate depth of anesthesia are the main high-risk situations. Airway protection requires the placement of cuffed tracheal tube. Cuffed tubes were considered as non-useful in children aged less than 6 to 8 years. They are however more frequently employed even in infants. Internal diameter of cuffed tubes should be reduced compared to uncuffed tubes. It is recommended to monitor cuff pressure if nitrous oxide is used during anesthesia. Crash induction is described with special reference to pediatric specificities.