Increase In Cuff Pressure Research Articles

Comparison of endotracheal tube cuff pressure changes using air versus nitrous oxide in anesthetic gases during laparoscopic abdominal surgeries

Background and objectivesThe purpose of this study was to compare the endotracheal tube cuff pressure changes during laparoscopic surgeries using air versus nitrous-oxide in anesthetic gas mixture; and to observe the incidences of postoperative sore throat, hoarseness and dysphagia. MethodsTotal 100 patients scheduled for elective laparoscopic abdominal surgery were allocated into two groups. Group A (n=50) received air while Group N (n=50) received nitrous-oxide in anesthetic gas mixture. After endotracheal intubation, cuff was inflated with air to achieve sealing pressure. Cuff pressure at baseline (sealing pressure), 30min, 60min and 90min was recorded with a manometer. Incidence of sore throat, hoarseness and dysphagia was noted at the time of discharge from post-anesthesia care unit and 24h after extubation. ResultsCuff pressure increased from baseline in both the groups. The increase in cuff pressure in Group N was greater than that in Group A at all time points studied (p<0.001). Within Group A, cuff pressure increased more at 90min than at 30min (p<0.05). Within Group N, increase in cuff pressure was more at each time point (30, 60 and 90min) than its previous time point (p<0.05). The incidence of sore throat in post-anesthesia care unit was higher in Group N than in Group A. ConclusionUse of nitrous-oxide during laparoscopy increases cuff pressure resulting in increased incidence of postoperative sore throat. Cuff pressure should be monitored routinely during laparoscopy with nitrous-oxide anesthesia.

Evaluation of Endotracheal Tube Cuff Pressure in Laparoscopic Cholecystectomy and Postoperative Sore Throat.

The use of nitrous oxide and carboperitoneum in laparoscopic cholecystectomy lead to increase in endotracheal tube cuff pressure. It may impair tracheal mucosal perfusion with subsequent tracheal damage. The purpose of this study was to evaluate cuff pressure and incidence of post-operative sore throat in patients undergoing laparoscopic cholecystectomy. In this prospective observational study, 128 patients aged 18-65 years of American Society of Anesthesiologist physical status I and II undergoing laparoscopic cholecystectomy were enrolled and allocated alternately into two groups, Study Group (Maintenance of anesthesia with sevoflurane 1-2%, oxygen/nitrous oxide mixture; 40/60), Control Group (Maintenance of anesthesia with sevoflurane 1-2%, oxygen/air mixture; 40/60) were analysed and comapared. Each group contained 64 patients. Aneroid manometer was used to monitor cuff pressure. Volume of air used to inflate the cuff, baseline cuff pressure, comparison of intraoperative cuff pressure and incidence of post-operative sore throat were measured. The study results demonstrated higher cuff pressure in study group at all times after the creation of carboperitoneum (p=0.00) with increased incidence of sore throat(p=0.004). Increase in endotracheal tube cuff pressure was noted with the use of nitrous oxide in laparoscopic cholecystectomy with subsequent post-operative airway complication. Monitoring of cuff pressure is simple, noninvasive and efficient way of achieving therapeutic cuff pressure of 20-30 cm of H2O and thus recommends its use.

Modification of Tracheal Cuff Shape and Continuous Cuff Pressure Control to Prevent Microaspiration in an Ex Vivo Pig Tracheal Two-Lung Model.

Microaspiration of subglottic secretions plays a pivotal role in ventilator-associated pneumonia. Impact of endotracheal tube cuff material and shape on tracheal sealing performance remains debated. The primary objective was to compare the tracheal sealing performance of polyvinyl chloride tapered, cylindrical and spherical cuffs. Secondary objectives were to determine the impact of continuous cuff pressure control on sealing performance and pressure variability. Prospective randomized ex vivo animal study. French research laboratory. Seventy-two ex vivo pig tracheal two-lung blocks. Blocks were randomly intubated with cylindrical (n = 26), tapered (n = 24), or spherical (n = 22) polyvinyl chloride endotracheal tube cuffs. Two milliliter of methylene blue were instilled above the cuff to quantify microaspirations, and lungs were ventilated for 2 hours. Continuous cuff pressure control was implemented in 33 blocks. Cuff pressures were continuously recorded, and after 2 hours, a microaspiration score was calculated. Tapered cuffs improved cuff sealing performance compared with spherical cuffs with or without continuous cuff pressure control. Compared with spherical cuffs, tapered cuffs reduced the microaspiration score without and with continuous pressure control by 65% and 72%, respectively. Continuous cuff pressure control did not impact sealing performance. Tapered cuffs generated higher cuff pressures and increased the time spent with overinflation compared with spherical cuffs (median [interquartile range], 77.9% [0-99.8] vs. 0% [0-0.5]; p = 0.03). Continuous cuff pressure control reduced the variability of tapered and spherical cuffs likewise the time spent with overinflation of tapered and cylindrical cuffs. Polyvinyl chloride tapered cuffs sealing enhanced performance at the cost of an increase in cuff pressure and in time spent with overinflation. Continuous cuff pressure control reduced the variability and normalized cuff pressures without impacting sealing performance.

Effect of various patient positions on endotracheal tube cuff pressure after adult cardiac surgery

Background: To avoid microaspiration or tracheal injury, the target endotracheal tube cuff pressure must be maintained 20–30 cmH2O. Changing in patients' positions may effect on endotracheal tube cuff pressure. The aim of this study was to investigate the effect of various patients' positions on endotracheal tube cuff pressure after adult cardiac surgery. Methods: This prospective, interventional study was conducted on 25 adult patients with orotracheal intubation for the cardiac surgery. Patients' endotracheal tube cuff pressure was assessed after surgery in a neutral starting position during an end-expiratory hold, and cuff pressure was regulated at 25 cmH2O. Then, ten changes in head position were performed: anteflexion, hyperextension, left and right lateral flexion, left and right rotation, semi-recumbent position (head elevation in 45°), recumbent position (head elevation in 10°), horizontal supine position, and finally, Trendelenburg position (10°). The observed cuff pressures were compared with the basic cuff pressure at the starting position. Results: Of total 250 measurements (25 participants in 10 positions), 109 (43/6%) were greater than the upper target limit of 30 cmH2O. In contrast, no measurements were less than the lower target limit of 20 cmH2O. 141 (56/4%) measurements were between the target limit of 20–30 cmH2O. All ten changes of patients' head position lead to statistically significant increase in endotracheal tube cuff pressure (P

Verification of endotracheal tube placement using electrical stimulation through electrodes placed on the endotracheal tube cuff.

Current methods for verification of endotracheal intubation can fail, particularly in emergency settings. We investigated whether a verification method using electrical stimulation through electrodes placed on the endotracheal tube cuff could distinguish endotracheal and esophageal intubations in an experimental setting. During three sequential sessions simulating emergency intubation without paralysis, rapid sequence intubation (RSI) with neuromuscular blockade, and intubation during cardiopulmonary resuscitation, eight pigs were intubated with an endotracheal tube fitted with two electrodes exposed on the cuff of the tube, first in the esophagus and next in the trachea or in reverse sequence. Cuff pressure was monitored during a 5-s electrical stimulation (20 mA, 80 Hz, 500 μs), and delta pressure was calculated as the difference between baseline cuff pressure and maximum cuff pressure during the electrical stimulation. Delta pressure was significantly higher in esophageal than in tracheal placements in all three sequential sessions (86.0 [78.3-89.7] vs. 6.5 [2.0-7.9] mmHg, P = 0.001; 16.6 [13.2-22.8] vs. 0.8 [0.3-2.6] mmHg, P = 0.004; 66.1 [60.0-84.7] vs. 2.7 [0.7-9.7] mmHg, P = 0.001). The delta pressure did not overlap between tracheal and esophageal intubations except for the session simulating RSI with neuromuscular blockade, in which one of eight esophageal placements showed a delta pressure within the delta pressure range of tracheal placements. Electrical stimulation through electrodes placed on the endotracheal tube cuff produced remarkably greater increases in cuff pressure in esophageal intubations than in tracheal intubations in an experimental setting.

Effect of Cuff Pressure Elevation on Internal Diameter of Tracheal Tube in Simulated Trachea

Application of nitrous oxide during anesthesia causes an increase in tracheal tube cuff pressure over time. The purpose of this study was to investigate the effect of an increase in cuff pressure on 3 types of tube (the Portex, Mallinckrodt, and Parker) commonly used for nasotracheal intubation. A cylindrical vessel was used to simulate a trachea. Cuff pressure was set at 0 cmH2O (R0) or 20 cmH2O (R20) at room temperature, or at 20 cmH2O (H20), 40 cmH2O (H40), 60 cmH2O (H60), or 80 cmH2O (H80) in 38°C hot water and pressure applied for 30 min. The value obtained at R0 was used as a reference (100%) and the rate of change under each condition determined. No change was observed at R20 in any of the 3 groups. In 38°C hot water, internal diameter in the Portex group decreased by 5.4% at H20 and 7.3% at H40, while that in the Mallinckrodt group decreased by 6% at H40. No significant change was observed in internal diameter in the Parker group, even when cuff pressure was increased. The internal diameter in the Portex group was the smallest at all cuff pressures in hot water. When the nasotracheal intubation tubes selected were placed in a simulated trachea and cuff pressure increased, internal diameter in the Portex and Mallinckrodt groups decreased.

Changes in endotracheal tube cuff pressure during laparoscopic surgery in head-up or head-down position.

BackgroundThe abdominal insufflation and surgical positioning in the laparoscopic surgery have been reported to result in an increase of airway pressure. However, associated effects on changes of endotracheal tube cuff pressure are not well established.Methods70 patients undergoing elective laparoscopic colorectal tumor resection (head-down position, n = 38) and laparoscopic cholecystecomy (head-up position, n = 32) were enrolled and were compared to 15 patients undergoing elective open abdominal surgery. Changes of cuff and airway pressures before and after abdominal insufflation in supine position and after head-down or head-up positioning were analysed and compared.ResultsThere was no significant cuff and airway pressure changes during the first fifteen minutes in open abdominal surgery. After insufflation, the cuff pressure increased from 26 ± 3 to 32 ± 6 and 27 ± 3 to 33 ± 5 cmH2O in patients receiving laparoscopic cholecystecomy and laparoscopic colorectal tumor resection respectively (both p < 0.001). The head-down tilt further increased cuff pressure from 33 ± 5 to 35 ± 5 cmH2O (p < 0.001). There six patients undergoing colorectal tumor resection (18.8%) and eight patients undergoing cholecystecomy (21.1%) had a total increase of cuff pressure more than 10 cm H2O (18.8%). There was no significant correlation between increase of cuff pressure and either the patient's body mass index or the common range of intra-abdominal pressure (10-15 mmHg) used in laparoscopic surgery.ConclusionsAn increase of endotracheal tube cuff pressure may occur during laparoscopic surgery especially in the head-down position.

Comparison of Cuff Pressure Increase upon Nitrous Oxide Exposure in air-Q Single Use, LMA-Supreme, and LMA-ProSeal; a Simulation Study

Purpose: A simulated lung model was used to compare the nitrous oxide-mediated increase in cuff pressure among three supraglottic devices air-Q® laryngeal airway single use (air-Q), LMA-Supreme® (Supreme), and LMAProSeal ®(ProSeal). Methods: The cuff pressure was initially adjusted to 10, 20, and 30 cmH2O. We changed the flow from without nitrous oxide (nitrous oxide 0%, oxygen 100 %) to with nitrous oxide (nitrous oxide 80%, oxygen 20%). Results: The cuff pressure of air-Q, Supreme and ProSeal were measured 15 and 30 minutes later. The cuff pressure of the air-Q and Supreme was significantly lower than that of the ProSeal after 15 and 30 minutes, regardless of the initial pressure (P<0.05). air-Q also showed significant lower cuff pressure than Supreme (P<0.05). Conclusion: These findings suggest that the air-Q may be more effective for preventing hyperinflation of cuff in response to nitrous oxide exposure.

Maintaining endotracheal tube cuff pressure at 20 mm Hg to prevent dysphagia after anterior cervical spine surgery; protocol of a double-blind randomised controlled trial

BackgroundIn anterior cervical spine surgery a retractor is obligatory to approach the spine. Previous studies showed an increase of endotracheal tube cuff pressure after placement of a retractor. It is known that high endotracheal tube cuff pressure increases the incidence of postoperative dysphagia, hoarseness, and sore throat. However, until now no evidence supports the fact whether adjusting the endotracheal tube cuff pressure during anterior cervical spine surgery will prevent this comorbidity. We present the design of a randomized controlled trial to determine whether adjusting endotracheal tube cuff pressure after placement of a retractor during anterior cervical spine surgery will prevent postoperative dysphagia.Methods/design177 patients (aged 18–90 years) scheduled for anterior cervical spine surgery on 1 or more levels will be included. After intubation, endotracheal tube cuff pressure is manually inflated to 20 mm Hg in all patients. Patients will be randomized into two groups. In the control group endotracheal tube cuff pressure is not adjusted after retractor placement. In the intervention group endotracheal tube cuff pressure after retractor placement is maintained at 20 mm Hg and air is withdrawn when cuff pressure exceeds 20 mm Hg. Endotracheal tube cuff pressure is measured after intubation, before and after placement and removal of the retractor. Again air is inflated if cuff pressure sets below 20 mmHg after removal of the retractor. The primary outcome measure is postoperative dysphagia. Other outcome measures are postoperative hoarseness, postoperative sore throat, degree of dysphagia, length of hospital stay, and pneumonia. The study is a single centre double blind randomized trial in which patients and research nurses will be kept blinded for the allocated treatment during the follow-up period of 2 months.DiscussionPostoperative dysphagia occurs frequently after anterior cervical spine surgery. This may be related to high endotracheal tube cuff pressure. Whether adaptation and maintaining the pressure after placement of the retractor will decrease the incidence of dysphagia, has to be determined by this trial.Trial registrationNetherlands Trial Register (NTR) 3542: http://www.trialregister.nl.

Perioperative transoesophageal echocardiography: past, present &amp; future

Perioperative transoesophageal echocardiography: past, present &amp; future

The effect of head rotation on efficiency of ventilation and cuff pressure using the PLMA in pediatric patients

BackgroundThis study examined whether changing the head position from neutral to side can affect expiratory tidal volume (TV) and cuff pressure when the appropriate sizes of a Proseal™ Laryngeal Mask Airway (PLMA)-depending on the body weight -are used in pediatric patients during pressure controlled ventilation (PCV).MethodsSeventy-seven children (5-30 kg) were divided into three groups according to their body weight, PLMA#1.5 (group I, n = 24), #2 (group II, n = 26), and #2.5 (group III, n = 27). After anesthesia induction, a PLMA was placed with a cuff-pressure of 60 cmH2O. The TV and existence of leakage at the peak inspiratory pressure (PIP) of 20 cmH2O, and the appropriate PIP for TV 10 ml/kg were examined. Upon head rotation to the left side, the TV, PIP, cuff pressure changes, and the appropriate PIP to achieve a TV 10 ml/kg were evaluated.ResultsHead rotation of 45 degrees to the left side during PCV caused a significant increase in cuff pressure and a decrease in TV, and there was no definite leakage. Changes in PIP and TV were similar in the three groups. The cuff pressure increased but there was no significant difference between the three groups.ConclusionsAlthough cuff pressure and TV of the PLMA were changed significantly after turning the head from the neutral position to the side, a re-adjustment of the cuff pressure and PIP to maintain a TV of 10 ml/kg can make the placed PLMA useful and successful in pediatric patients under general anesthesia.

Endotracheal Tube Intracuff Pressure During Helicopter Transport

We evaluate changes in endotracheal tube intracuff pressures among intubated patients during aeromedical transport. We determine whether intracuff pressures exceed 30 cm H(2)O during aeromedical transport. During a 12-month period, a helicopter-based rescue team prospectively recorded intracuff pressures of mechanically ventilated patients before takeoff and as soon as the maximum flight level was reached. With a commercially available pressure manometer, intracuff pressure was adjusted to < or =25 cm H(2)O before loading of the patient. The endpoint of our investigation was the increase of endotracheal tube cuff pressure during helicopter transport. Among 114 intubated patients, mean altitude increase was 2,260 feet (95% confidence interval [CI] 2,040 to 2,481 feet; median 2,085 feet; interquartile range [IQR] 1,477.5 to 2,900 feet). Mean flight time was 14.8 minutes (95% CI 13.1 to 16.4 minutes; median 13.5 minutes; IQR 10 to 16.1 minutes). Intracuff pressure increased from 28.7 cm H(2)O (95% CI 27.0 to 30.4 cm H(2)O [median 25 cm H(2)O; IQR 25 to 30 cm H(2)O]) to 62.6 cm H(2)O (95% CI 58.8 to 66.5 cm H(2)O; median 58; IQR 48 to 72 cm H(2)O). At cruising altitude, 98% of patients had intracuff pressures > or =30 cm H(2)O, 72% had intracuff pressures > or =50 cm H(2)O, and 20% even had intracuff pressures > or =80 cm H(2)O. Endotracheal cuff pressure during transport frequently exceeded 30 cm H(2)O during aeromedical transport. Hospital and out-of-hospital practitioners should measure and adjust endotracheal cuff pressures before and during flight.

Effects of retractor application on cuff pressure and vocal cord function in patients undergoing anterior cervical discectomy and fusion

Anterior cervical discectomy and fusion is a commonly performed procedure for prolapse of cervical intervertebral disc. It involves retraction of soft tissue of neck for adequate exposure of anterior spinal canal. Increased cuff pressure with retractor application may affect the postoperative vocal cord function. Cuff pressures of tracheal tube were measured continuously in 37 patients using air-filled pressure transducer connected to the pilot balloon. Changes of pressure from baseline values were noted after application of cervical retractor. At the end of procedure, vocal cord movement was observed using fibreoptic bronchoscope. Significant increase in cuff pressure (168% of baseline values) and airway pressure of tracheal tube during cervical retraction was observed. The vocal cord function was assessed using fibreoptic laryngoscope. One patient developed right vocal cord palsy (2.7%) and two patients had postoperative hoarseness of voice (5.4%). All these complications improved over a period of time. It is suggested that the cuff of tracheal tube should be inflated to achieve ‘just seal’, with adequate cuff pressure monitoring. Intermittent release of cervical retraction may help to prevent laryngeal morbidities.

The Effects of the Alkalinization of Intracuff Lidocaine after Nitrous Oxide Anesthesia

Background: Diffusion of nitrous oxide into the cuff of the endotracheal tube (ETT) results in an increase in cuff pressure. This method was used to test whether tracheal morbidity is related to fill the cuff of the endotracheal tube with alkalinized lidocaine instead of air or lidocaine only. Methods: Adult patients scheduled for total thyroidectomy surgery were randomly enrolled (n = 30 for each group). The ETT cuff was filled with air 6 ml (Group C), with 2% lidocaine 6 ml (Group L), or with alkalinized lidocaine (4 ml or 2 ml of 2% lidocaine) using 2 ml (Group A) or 4 ml (Group B) of 8.4% NaHCO3. After tracheal extubation, sore throat was evaluated by visual analog scale as the main end-point of the study. Results: Compared with group air or lidocaine only, the alkalinized-lidocaine groups had a significant reduction in sore throat during the 24-h postoperative period (P ＜ 0.001). The difference was not significant between the two alkalinized lidocaine groups. Cough before tracheal extubation, nausea, postoperative vomiting, dysphonia, and hoarseness after extubation were decreased in the alkalinized-lidocaine groups compared with Group C and L, and a better tolerance was recorded with alkalinized-lidocaine groups compared with Group C and L. Conclusions: We concluded that use of intracuff alkalinized lidocaine is an effective adjunct to endotracheal intubation instead of air or lidocaine only during nitrous oxide anesthesia, however there were no differences between two alkalinizations. (Korean J Anesthesiol 2008; 54: 384∼8)

Outer diameter and shape of paediatric tracheal tube cuffs at higher inflation pressures

Cuffed tracheal tubes are becoming increasingly popular in paediatric anaesthesia and intensive care medicine. To avoid cuff related complications and airway morbidity, a thorough understanding of cuff volume/pressure behaviour and management is required. In this study, the outer cuff diameter and form stability of the cuff at high cuff pressure were assessed in a series of different paediatric cuffed tracheal tubes with internal diameter of between 3.0 and 5.0 mm. The main findings were that small amounts of inflated air led to a rapid increase in cuff pressure and volume and that the outer cuff diameters increased to 2-2.5 times the age-corresponding internal tracheal diameter following inadvertent syringe inflation. Careful cuff inflation under cuff pressure monitoring and/or automatic cuff pressure release is recommended in paediatric tracheal tube cuffs to prevent airway damage caused by manual inflation, pilot balloon compression and nitrous oxide diffusion.

Ventricular hypertrophy and arterial hemodynamics following deprivation of nitric oxide in rats

In the present study, we elucidated the possible role of hemodynamic parameters and chemical factors in the development of ventricular hypertrophy (VH) following chronic nitric oxide (NO) deprivation with N ω-nitro- l-arginine methyl ester ( l-NAME). Impedance spectral analysis was used to obtain the arterial hemodynamics including the steady and pulsatile components. Body weight (BW), left ventricular (LV) weight (LVW), LVW / BW ratio, LV collagen volume fraction (LVCVF), cyclic GMP, and nitrite/nitrate were measured. The extent of VH was evaluated by the LW/BW, total number, numerical density, and size of cardiomyocytes. Sprague–Dawley rats were given l-NAME 10, 20, and 40 mg/kg/day from the age of 10 to 18 weeks. Control and age-matched rats were given vehicle for the same period. Treatment of l-NAME for 8 weeks caused a dose-dependent increase in tail cuff pressure and a reduction in BW with increases in LVW, LVW/BW, number, numerical density, and size of myocytes. There was elevation of aortic pressure with decreases in cardiac output, and arterial compliance. The total peripheral resistance, characteristic impedance and pulse wave reflection were increased. Histological finding revealed severe myocardial hypertrophy and fibrosis with fibroblast infiltration. The LVCVF was increased, while LV cGMP and nitrite/nitrate were reduced in a dose-dependent manner. The results suggest that chronic NOS blockade causes hypertension, impairment of large vessel properties, and VH. The development of VH may result partly from the decreases in cGMP and nitrite/nitrate in the ventricle. Correlation analysis indicates that the extent of VH is equally related to the steady and pulsatile hemodynamics.

Assessment of a new method to distinguish esophageal from tracheal intubation by measuring the endotracheal cuff pressure in a porcine model

Study objectives: Timely assessment of proper endotracheal tube placement is necessary to avoid serious morbidity and mortality. Various methods are used to verify tracheal intubation and to detect esophageal intubation. Many of these methods fail under certain circumstances. With the knowledge of differences of anatomic structure and resistance against certain volume between trachea and esophagus, we conduct an animal study to evaluate the usefulness of the endotracheal cuff pressures in endotracheal and esophageal intubation to detect esophageal intubation. Methods: Six swine were anesthetized and intubated with regular 7.5-mm endotracheal tube (Mallincrodt Medical Intermediate Hi-Lo). After confirmation of tracheal intubation by fiberoptic bronchoscopy, a second endotracheal tube (also 7.5 mm) was placed in the esophagus of each swine, and the cuffs were not inflated. Both tubes extended the same distance from the mouth. Each pilot balloon of both tubes was connected to a 10-mL syringe and a manometer by a 3-way stopcock. The cuff pressure was measured after incremental 1-mL filling volume of air. The data of cuff pressure caused by variable volume in both endotracheal and esophageal intubations were compared. The pressure-volume relationships in both intubations were also measured. Results: The endotracheal cuff pressures (mean±SD) increased significantly in esophageal intubations compared with endotracheal intubation (115±12.4 versus 53±9.8 cm H₂O, at 10-mL inflation of air, <i>P</i><.05). The pressure and the rate of increase in cuff pressure were also significantly higher (<i>P</i><.05) in the esophageal intubation during the inflation of the cuff in the study. Conclusion: In this animal study, the cuff pressure of esophageal intubation was significantly higher than that of endotracheal intubation under the same inflated volume. It may provide an adjunctive, simple, rapid, and reliable method to verify endotracheal intubation and detect the occurrence of esophageal intubation by measuring the endotracheal cuff pressure.

Does sealing endotracheal tube cuff pressure diminish the frequency of postoperative laryngotracheal complaints after nitrous oxide anesthesia?

Study objectives To study endotracheal tube (ETT) cuff pressures during nitrous oxide (N 2O) anesthesia when the cuffs are inflated with air to achieve sealing pressure, and to evaluate the frequency of postoperative laryngotracheal complaints. Design Prospective, randomized, blind study. Setting Metropolitan teaching hospital. Patients 50 ASA physical status I and II patients scheduled for elective abdominal surgery. Interventions Patients received standard general anesthesia with 66% N 2O in oxygen. In 25 patients, the ETT cuff was inflated with air to achieve a sealing pressure (P seal group). In 25 patients, the ETT cuff was inflated with air to achieve a pressure of 25 cm H 2O (P 25 group). Measurements and main results ETT intracuff pressures were recorded before (control) and at 30, 60, 90, 120, and 150 minutes during N 2O administration. We investigated the frequency and intensity of sore throat, hoarseness, and dysphagia in patients in the Post-Anesthesia Care Unit (PACU) and 24 hours following tracheal extubation. The cuff pressures in the P seal group were significantly lower than in the P 25 group at all time points studied (p < 0.001), with a significant increase with time in both groups (p < 0.001). The cuff pressures exceeded the critical pressure of 30 cm H 2O only after 90 minutes in the P seal group and already by 30 minutes in the P 25 group. The frequency and intensity of sore throat, hoarseness, and dysphagia were similar in both groups in the PACU and 24 hours after tracheal extubation (p > 0.05). Conclusions Minimum ETT sealing cuff pressure during N 2O anesthesia did not prevent, but instead attenuated, the increase in cuff pressure and did not decrease postoperative laryngotracheal complaints.

Intracuff Pressure Monitoring during Nitrous Oxide Anesthesia when Using the Soft Seal® Laryngeal Mask

We thank Drs. Kanazawa and Suzuki for showing interest in our article1and their conclusion that the Portex Soft Seal® laryngeal mask (LM) (Smiths Medical International, Portex Ltd., Hythe, Kent, United Kingdom) offers good laryngeal seal and clinical performance. We have shown that changes in intracuff pressure in Soft Seal® LM during nitrous oxide anesthesia are minimal. The use of new materials in the design of endotracheal tube cuffs has resulted in much lower increases in cuff pressure during nitrous oxide anesthesia.2In the Soft Seal® LM cuff, the plasticizer added to soften the polyvinyl chloride makes the cuff less permeable to nitrous oxide. We have been informed by the manufacturers of the Soft Seal® LM that the material used in manufacturing the cuff of the Soft Seal® LM has changed more recently since our study. Our continuing, unpublished work on methods of insertion of the Soft Seal® LM has shown results similar to those published. We have no explanation for the pressure changes Drs. Kanazawa and Suzuki describe. The only comment we can make is that the very small numbers of patients studied, six patients, with no information about the laryngeal mask size, position during surgery, the method used to measure the cuff pressure, and the longer duration of anesthesia may have affected the results of their limited study.* Catharina Hospital, Eindhoven, The Netherlands. zundert@iae.nl

A New Cuff Design Prevents N2O Diffusion

Henri-Mondor Hospital, Créteil, France. xacombes@wanadoo.frI read with interest the letter of Dr. Al-Shaikh. As we have emphasized it in our article, filling the cuff with saline was done for the purpose of the study and cannot be recommended in routine clinical practice. 1It is clear that a tube cuff design that prevents increase in the intracuff pressure during N2O anesthesia is of great interest for daily clinical practice. The new design endotracheal tube cuff evaluated by Dr. Al-Shaikh et al. , 2because of a very low permeability to N2O, allowed a very good intracuff pressure stability during N2O anesthesia and seems particularly promising. Nevertheless, we believe that intracuff pressure measurement after cuff inflation is necessary. Indeed, the pressure/volume curve of endotracheal tube cuff has an asymptotic shape and reaches rapidly (for low volume of the cuff) a relative plateau around which very small variations of volume are associated with large increase in cuff pressure. Then, even without N2O diffusion, the cuff pressure can be high because of an inappropriate initial cuff inflation. We recommend, whatever the endotracheal tube device used, at least one cuff pressure control after initial cuff inflation to prevent excessive intracuff pressure and occurrence of tracheal injury.