Red Rubber Endotracheal Tubes Research Articles

We should care more about intracuff pressure: The actual situation in government sector teaching hospital

Endotracheal tube (ETT) should have intracuff pressure (ICP) in the range of 20 to 30 cm water (H2O). In this observational study, we studied the trend amongst anaesthesiologist in choosing the type of ETT and their ability to assess optimum ICP clinically. After institutional ethics committee approval, we observed 75 patients under general endotracheal anaesthesia in Government Medical College. Anaesthesiologists were blinded to study purpose. The type of ETT used and magnitude of ICP was recorded. ICP was measured using simple aneroid manometer. Once the pressure was measured, it was readjusted to normal range and nitrous oxide was allowed to start. Red rubber tube was used in 18.7% and polyvinyl chloride (PVC) in 81.3% cases. The anaesthesiologists were not able to assess ICP in the recommended range clinically in 100% cases when red rubber ETT was used and in 40% cases when portex ETT was used. Red rubber ETT (reusable) with low-volume high-pressure cuff is still in use, though the trend is shifting towards more of using PVC ETT. Anaesthesiologists were not able to inflate the ETT cuff to the recommended range in spite of their clinical expertise (more than 5 years of teaching experience) in significant number of cases. We recommend the use of simple aneroid manometer for objective monitoring of ICP over subjective assessment, not only in red rubber, but also in PVC ETT.

Intraoperative Nasogastric Tube Insertion with Non-ProSeal Laryngeal Mask Airway in Place

To the Editor: It is difficult to place a nasogastric tube (NGT) behind a properly positioned laryngeal mask airway (LMA). We describe a simple technique of NGT insertion in two patients who had an LMA in place. The first patient was a non-fasted primigravida scheduled for emergency cesarean section for fetal bradycardia. Following several failed intubation attempts, a #3.0-LMA-Classic™ was used to secure the airway. After safe delivery of the baby, the surgeon requested placement of an NGT for stomach evacuation. A well-lubricated 6.0-mm inner diameter cuffed red rubber endotracheal tube (ETT) (Rusch, Munchen, Germany) was passed through right nostril into the nasopharynx and further into hypopharynx, where the cuff was inflated to maximum. The NGT (Romsons Sci & Surg Ltd., Agra, India) was introduced through the nasal ETT into the stomach without difficulty (Fig. 1). Residual fluid (50 mL) and gases were suctioned.Figure 1.: Side view of the patient showing nasogastric tube placed through nasal cuffed red rubber tube behind laryngeal mask airway cuff.The second case was a 55-yr-old woman scheduled for laparoscopic abdominal hysterectomy. Again, after several failed intubation attempts, a #3.0 intubating LMA (ILMA-Fastrach™) was inserted to secure the airway. A fiberoptic bronchoscope (FOB)-assisted ILMA endotracheal tube was then guided into the trachea. We could not remove the LMA because the stabilizing rod was unavailable. The surgeon requested for evacuation of gases before institution of carboperitoneum and trocar insertion. A well-lubricated NGT with a soft angiographic guide wire was passed into the nasopharynx. An orally introduced FOB was advanced behind the ILMA cuff and used to guide the NGT behind the partially inflated ILMA cuff. Both were advanced concurrently (cm by cm; NGT first, then FOB, and so on). Once the NGT was advanced beyond the hypopharynx (the tip of LMA), the NGT alone was advanced into the esophagus and subsequently into the stomach (Fig. 2).Figure 2.: Lateral fluoroscopic image depicting intubating laryngeal mask airway (ILMA) and ILMA - tracheal tube in place. Nasogastric tube is passed behind the ILMA.Meta-analysis has shown that gastric tube insertion is less successful behind the LMA cuff as compared with via the drain tube (1). Ozer et al. delineated the utility of FOB imaging to avoid failure of NGT insertion in intubated patients (2). Our first method used an inflated red rubber ETT cuff to displace the LMA cuff forward whereas the second technique used FOB-guided NGT insertion. These techniques may be helpful for nasogastric tube insertion in patients with an LMA in place. Amitabh Dutta, MD Neelam Ganguly, MD Jayashree Sood, MD, FFARCS, PGDHHM V.P. Kumra, MD, DA, DAC Department of Anaesthesiology, Pain & Perioperative Medicine Sir Ganga Ram Hospital New Delhi, India [email protected]

The High-Pressure Characteristics of the Cuff of the Intubating Laryngeal Mask Endotracheal Tube

The modern polyvinylchloride endotracheal tube (ET) has a large cuff that conforms to the shape of the trachea and can seal it with a low pressure. This large-volume, low-pressure cuffed ET design has, therefore, largely replaced the older red rubber ET which has a small-volume, high-pressure cuff that predisposes to tracheal ischemic complications, particularly during long-term use (1). The new intubating laryngeal mask endotracheal tube (ILM-ET) is an ET used in conjunction with the LMA-Fastrach™ Laryngeal Mask (Euromedical) for blind and fiberoptic-guided tracheal intubation. No specific information is currently available regarding the compliance characteristics of the ILM-ET cuff, which appears to be relatively small. Therefore, this study was designed to measure the compliance of the cuff of the ILM-ET and to compare it with that of the cuff of the polyvinylchloride and red rubber ET. Four size 7.5-mm (inside diameter) of each ET type was tested. The cuff of each tube was incrementally inflated in air, and the corresponding cuff pressure was measured using a calibrated pressure manometer. The ILM-ET cuff clearly exhibited high-pressure characteristics (Figure 1). At cuff volumes used during routine clinical practice, cuff pressure approached 100 mm Hg. Figure 1: The compliance curves of the cuff of three types of size 7.5-mm (inside diameter) endotracheal tubes (ET). Values are mean ± SD. Mallinckrodt, St. Louis, MO; Rüsch, High Wycombe, England; Euromedical, San Diego, CA.During inflation of a low-volume, high-pressure cuff, part of the cuff pressure is consumed in stretching the cuff wall itself. The pressure inside such a cuff is, therefore, higher than the pressure exerted on the tracheal mucosa (CT pressure) by the amount of pressure needed to maintain cuff inflation (2). Nonetheless, when using a low-volume, high-pressure cuffed ET, such as the ILM-ET, it is prudent to attempt to limit the CT pressure. Knowlson and Bassett (3) demonstrated that this could be achieved by inflating the cuff to the minimal volume that sealed the trachea (minimal occlusion volume [MOV]). The authors performed in vivo measurements of CT pressure in patients undergoing anesthesia with a low-volume, high-pressure cuff in place. The CT pressure ranged between 25 and 40 mm Hg at MOV, with a peak inflation pressure of 15 mm Hg and rose rapidly to very high levels with further increments in cuff volume. They concluded from their findings that low-volume, high-pressure cuffs were capable of sealing the trachea with reasonably low CT pressures as long as the cuff was maintained at MOV. The high-pressure characteristics of the cuff of the ILM-ET can be used as an argument against its long term use. Other problems which can be encountered during the long term use of the ILM-ET are the susceptibility to biting and the potential for accumulation of secretions at the reduced-caliber tube tip. In conclusion, the cuff of the ILM-ET is a low-volume, high-pressure cuff. It is, therefore, important when using this ET to maintain its cuff volume at MOV. Esme Riley MD Kerry DeGroot MD Medhat Hannallah MD, FFARCS

Evaluation of a new laser-resistant fabric and copper foil-wrapped endotracheal tube.

The risk of an endotracheal tube's combustion during laser airway surgery necessitates the use of special anesthetic techniques and equipment to prevent this complication. This study was designed to evaluate the Laser-Trach(TM), a new laser-resistant rubber endotracheal tube for use during laser airway surgery. The Laser-Trach endotracheal tubes that were evaluated were size 6.0 mm internal diameter (ID) red rubber endotracheal tubes which had been commercially wrapped by Kendall-Sheridan (Mansfield, Mass.) with copper foil tape and overwrapped with fabric. The fabric layer was saturated with water prior to our tests, as recommended by the manufacturer. The Laser-Trach endotracheal tubes were compared with plain (bare) size 6.0 mm ID Rusch red rubber endotracheal tubes. The tubes under study were positioned horizontally on wet towels in air and had 5 L x min(-1) of oxygen flowing through them. They were subjected to continuous laser radiation at 40 W from either a CO2 or an Nd-YAG laser. The Nd-YAG laser was propagated via a 600-micron fiber bundle. Each laser was directed perpendicularly at the shaft of the endotracheal tube being studied, and its output was continued until a blowtorch fire occurred or 60 seconds had elapsed. Sixty seconds of CO2 laser fire did not ignite any of the eight Laser-Trach endotracheal tubes tested. However, blowtorch ignition of all eight bare rubber tubes tested occurred after 0.87 +/- 0.21 (mean +/- SD) seconds of CO2 laser fire. Nd-YAG laser contact with the Laser-Trach endotracheal tubes caused the perforation and blowtorch ignition of all eight tubes tested after 18.79 +/- 7.83 seconds. This was a significantly (P<.05) longer time than the 5.45 +/- 4.75 seconds required for the blowtorch ignition of all eight plain rubber endotracheal tubes tested with the Nd-YAG laser. Our results show that under the conditions of this study, the shafts of the Kendall-Sheridan Laser-Trach endotracheal tubes were resistant to the C02 laser. However, this endotracheal tube is not recommended for use with the Nd-YAG laser.

Which is the safest endotracheal tube for use with the CO 2 laser? A comparative study

Study Objective: To compare the efficacy of special endotracheal tubes manufactured for carbon dioxide (CO 2) laser surgery with foil-wrapped and plain red rubber (RR) endotracheal tubes. Setting: Research laboratory of a metropolitan, university-affiliated medical center. Design and Interventions: Six types of endotracheal tubes were studied. Each had 5 L/min of oxygen passing through it and was exposed to 69 watts of continuous CO 2 laser radiation for 1 minute or until combustion occurred. Measurements and Main Results: The plain RR endotracheal tube burned within 15 seconds of laser impact. Aluminum foil-wrapped and copper foil-wrapped RR endotracheal tubes were not affected by the C02 laser. The shaft of a specially manufactured stainless steel endotracheal tube was not affected by 1 minute of CO 2 laser exposure. The shafts of two special endotracheal tubes made of silicone and metal burned vigorously under laser fire. Conclusion: Copper foil-wrapped RR tubes, aluminum foil-wrapped RR tubes, or stainless steel tubes are recommended for laser airway surgery.

Laser resistant stainless steel endotracheal tube: Experimental and clinical evaluation

A fire due to endotracheal tube (ET) ignition is a catastrophic event that may occur during laser surgery of the upper airway, regardless of the wavelength utilized. Although methods exist that permit laser surgery without an ET, this is frequently not feasible. The current investigation was undertaken to evaluate the efficacy of a double-cuffed stainless steel ET, first in the laboratory and subsequently in a clinical setting. Bench testing was performed using CO2 (both standard and milliwatt) and KTP/532 lasers. Only the distal polyvinyl chloride cuffed end of the tube was potentially ignitable, however, the appropriate use of saline to fill the cuffs allowed only for cuff perforation without ignition. Canine testing was performed in 10 animals: 4 dogs were intubated from 3 to 4.5 hours with the laser resistant stainless steel endotracheal tube (LRSS-ET) (Laser-Flex Tracheal Tube; Mallinckrodt Anesthesia Products, St. Louis, MO) and 2 with an aluminum tape wrapped red rubber ET. Visual and histological examination were performed in both groups at 3 and 7 days. Four dogs underwent CO2 laser laryngeal surgery with visual and histological examination performed at 7 days postoperatively. No untoward effects could be demonstrated due to the LRSS-ET. A clinical study was then performed in 24 patients who underwent laser surgery of the upper aerodigestive tract with either a CO2 or KTP/532 laser. In all cases ventilation was adequate, the shaft of the LRSS-ET proved impervious to the laser, and the distal end of the tube protected the tracheobronchial tree safely.(ABSTRACT TRUNCATED AT 250 WORDS)

What is the Safest Foil Tape for Endotracheal Tube Protection during Nd-YAG Laser Surgery? A Comparative Study

Metallic tapes have been shown to protect combustible endotracheal tubes from the CO2 laser; however, no adequate means of protecting such tubes from the Nd-YAG laser has yet been found. In this investigation, five different metallic tapes were evaluated as protection for red rubber endotracheal tubes from an Nd-YAG laser set to 50 W. Radio Shack no. 44-1155 and 3M no. 1430 were quickly perforated by the laser. Laser contact with the adhesive side of 3M no. 433 resulted in combustion. The nonadhesive side of the Venture copper tape was not affected by the laser; however, when its adhesive side was struck, a fire occurred. 3M no. 425 tape provided the best protection: no effect was seen when the laser was aimed at its nonadhesive side for 1 min, with only smoking of the tape evident when its adhesive side was tested. Finally, 3M no. 425 and Venture copper foil tapes were shown to be resistant to an Nd-YAG laser set to 110 watts in an atmosphere of 98% O2.

What Is the Safest Endotracheal Tube for Nd-YAG Laser Surgery????A Comparative Study

To determine whether a safe endotracheal tube for Nd-YAG surgery could be found, an Nd-YAG laser operating at 50 W was directed at six different endotracheal tubes that had 5 L/min of oxygen flowing through them. A plain Rusch red rubber endotracheal tube, a Bivona Fome-cuff laser endotracheal tube, a stainless steel Mallinckrodt Laser-Flex endotracheal tube, and a Xomed Laser-shield endotracheal tube were all ignited and perforated by the laser within 12 s. The combustion of the Mallinckrodt endotracheal tube can be explained by the high energy density of the laser that, in rapidly heating the metal, was able to cause its combustion in 100% oxygen. Red rubber endotracheal tubes wrapped with 3M No. 425 or Venture copper foil tape were unaffected by 1 min of exposure to the laser beam. They are recommended for clinical use.

Laser Safety in Otolaryngology???Head and Neck Surgery

Two investigations concerning anesthetic and educational considerations for laser safety in microlaryngeal carbon dioxide laser surgery have been performed. The first study demonstrated that attendance at a "hands-on" laser surgery course that stressed safety precautions was associated with a reduced rate of laser-related complications in the selected group of otolaryngologists who participated in the course, when compared to another selected group of otolaryngologists who were members of a senior otolaryngology society, and surveyed solely on the basis of their society membership. The second series of studies compared the incendiary characteristics of three endotracheal tubes in various mixtures of oxygen, diluted with either helium or nitrogen. It was determined that the polyvinyl chloride tube should not be used for laser surgery, even when wrapped with reflective, metallic tape. The safest anesthetic gas mixture was found to be 30% oxygen in helium; the addition of 2% halothane did not have an adverse effect, as had been previously reported. Both the Xomed Laser-Shield and Rusch red rubber endotracheal tubes were found to be safe, when used with the laser in the pulsed mode in an atmosphere of 100% oxygen. When the laser was used in the continuous mode, both tubes ignited in an atmosphere of 30% oxygen in helium. These findings challenged the previously reported levels of safety associated with the use of an unwrapped Xomed tube. Based on the results of this investigation, it has been concluded that both the Rusch red rubber tube and the Xomed Laser-Shield tube should be wrapped with reflective, metallic tape, when used for cases of microlaryngeal surgery with the carbon dioxide laser.

Injuries to the bronchi and lungs caused by laser-ignited endotracheal tube fires.

A CO2 laser attached to an operating room microscope was used to produce extraluminal and intraluminal ignition of various endotracheal tubes in dogs. Extraluminal ignition was produced in Silastic and red rubber endotracheal tubes. The red rubber tube ignited before the tube lumen was penetrated. The Silastic tube failed to ignite while the cuff was inflated. When the cuff was deflated, ignition occurred before the lumen was penetrated. No lung or bronchial injuries were detected in the red rubber or Silastic endotracheal tube extraluminal fires. Intraluminal fires were produced in Silastic, red rubber, and polyvinylchloride (PVC) endotracheal tubes. Microscopic examination of the bronchi and lungs revealed severe injuries in dogs intubated with the PVC and red rubber endotracheal tubes. No injuries to the bronchi and lungs were detected in the Silastic tube group, although the potentially toxic effects of silica ash require further investigation.

Increases in Cuff Volume and Pressure in Red Rubber Endotracheal Tubes during Anaesthesia

Increases in endotracheal tube cell volume and pressure during anaesthesia have been reported to be due to the diffusion of nitrous oxide into the cuff. This study compared cuff volume and pressure changes in anaesthetized intubated patients who were ventilated with those allowed to breath spontaneously. The cuffs of Magill red rubber endotracheal tubes were inflated with either air or a nitrous oxide-oxygen mixture. Serial pressure and volume recordings confirmed that both parameters increased when the cuff was inflated with air. The increase in cuff pressure was however, greater during intermittent positive pressure ventilation than for spontaneous respiration. There were no significant changes when the cuff was inflated with the nitrous oxide-oxygen mixture.