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PubMed2006

Synchronous airway lesions and associated anomalies in children with laryngomalacia evaluated with rigid endoscopy.

OBJECTIVE: To evaluate the prevalence of synchronous airway lesions (SALs) and associated anomalies in children with laryngomalacia requiring rigid endoscopic evaluation, the clinical significance of such lesions, and safety and outcome of selective rigid endoscopy. SETTING: National Children's Hospital. DESIGN AND METHOD: Retrospective analysis. The records of all children diagnosed with laryngomalacia who underwent rigid endoscopy were identified from the surgical database over a 4-year period. OUTCOME MEASURES: Age at presentation, signs and symptoms at time of presentation, presence of associated neurological and/or congenital anomalies (ANCAs), presence of synchronous airway lesions, need for surgical intervention, complications and time to resolution of symptoms were assessed. RESULTS: There were 26 children in the study. The mean age at presentation ranged from 0 to 10 months of age. One child (3.8%) required surgical intervention for severe isolated laryngomalacia. Seven children (26.9%) had at least one SAL identified. Of these, six (85.7%) were previously diagnosed on flexible fibreoptic laryngoscopy (FFL). Two of the seven children with SALs required surgical management of the SAL. Prematurity and ANCAs prolonged hospital stays in these children. However, the presence of SALs did not affect the length of hospital stay or the time to resolution of symptoms. Symptom resolved in all children by 3 years of age, whether or not SALs or ANCAs are present. There was no adverse outcome in the study group. CONCLUSION: Despite having indications for rigid endoscopy, many children with laryngomalacia do not have SALs, which even when present, are rarely clinically significant. SALs and ANCAs do not impact the time to symptom resolution. The current indications for rigid endoscopy in the evaluation of laryngomalacia are appropriate and safe.

Female↗
PubMed2006

Separating brain motion into rigid body displacement and deformation under low-severity impacts.

The relative motion of the brain with respect to the skull has been widely studied to investigate brain injury mechanisms under impacts, but the motion patterns are not yet thoroughly understood. This work analyzes brain motion patterns using the most recent and advanced experimental relative brain/skull motion data collected under low-severity impacts. With a minimum total pseudo-strain energy, the closed-form solutions for rigid body translation and rotation were obtained by matching measured neutral density target (NDT) positions with initial NDT positions. The brain motion was thus separated into rigid body displacement and deformation. The results show that the brain has nearly pure rigid body displacement at low impact speed. As the impact becomes more severe, the increased brain motion primarily is due to deformation, while the rigid body displacement is limited in magnitude for both translation and rotation. Under low-severity impacts in the sagittal plane, the rigid body brain translation has a magnitude of 4-5 mm, and the whole brain rotation is on the order of +/-5 degrees.

Acceleration↗
PubMed2005

Efficient multi-modal dense field non-rigid registration: alignment of histological and section images.

We describe a new algorithm for non-rigid registration capable of estimating a constrained dense displacement field from multi-modal image data. We applied this algorithm to capture non-rigid deformation between digital images of histological slides and digital flat-bed scanned images of cryotomed sections of the larynx, and carried out validation experiments to measure the effectiveness of the algorithm. The implementation was carried out by extending the open-source Insight ToolKit software. In diagnostic imaging of cancer of the larynx, imaging modalities sensitive to both anatomy (such as MRI and CT) and function (PET) are valuable. However, these modalities differ in their capability to discriminate the margins of tumor. Gold standard tumor margins can be obtained from histological images from cryotomed sections of the larynx. Unfortunately, the process of freezing, fixation, cryotoming and staining the tissue to create histological images introduces non-rigid deformations and significant contrast changes. We demonstrate that the non-rigid registration algorithm we present is able to capture these deformations and the algorithm allows us to align histological images with scanned images of the larynx. Our non-rigid registration algorithm constructs a deformation field to warp one image onto another. The algorithm measures image similarity using a mutual information similarity criterion, and avoids spurious deformations due to noise by constraining the estimated deformation field with a linear elastic regularization term. The finite element method is used to represent the deformation field, and our implementation enables us to assign inhomogeneous material characteristics so that hard regions resist internal deformation whereas soft regions are more pliant. A gradient descent optimization strategy is used and this has enabled rapid and accurate convergence to the desired estimate of the deformation field. A further acceleration in speed without cost of accuracy is achieved by using an adaptive mesh refinement strategy.

Algorithms↗
PubMed2005

A simple and reliable predictor for an adequate laryngeal view with rigid endoscopic laryngoscopy.

OBJECTIVES: It is sometimes impossible to obtain an adequate laryngeal view during rigid endoscopic laryngoscopy. This may be due to a high tongue base. Our study seeks to determine a correlation between tongue base level and the adequacy of laryngeal view obtained with a 70-degree rigid endoscope. STUDY DESIGN AND SETTING: Over a period of 4 months, patients from a voice clinic were gathered and categorized into class I to III according to Mallampati et al (1985). Rigid laryngo-videostroboscopy was conducted to assess the larynx and the adequacy of the view was recorded. RESULTS: 74 patients were recruited. The number of adequate views were: class I = 18/20 (90%); class II = 20/33 (60.6%); class III = 7/21 (33.3%). chi 2 analysis demonstrated significance trend in all 3 classes. CONCLUSION: The level of the tongue base correlated well with the adequacy of laryngeal view obtained from a 70-degree rigid endoscope. This can be used to predict the success of obtaining adequate views during rigid laryngoscopy.

Adolescent↗
PubMed1999

A randomized prospective study comparing rigid to balloon dilators for benign esophageal strictures and rings.

BACKGROUND: The optimum choice of dilator (rigid vs. balloon) for benign esophageal strictures has not been well studied. The aim of this study was to compare the immediate relief of dysphagia and the incidence of repeat dilatation within the first year with the use of either a rigid (Savary) dilator or balloon dilator for benign lower esophageal strictures. METHODS: Patients with dysphagia found to have benign esophageal strictures during endoscopy were randomized to undergo dilation with a rigid (Savary) or a balloon dilator (Microvasive or Bard). The 1-year incidence of repeat dilatation was estimated by the Kaplan-Meier method. RESULTS: A total of 251 subjects were stratified at entry according to the type of stricture (peptic vs. Schatzki ring) and severity of stricture (mild vs. moderate/severe) and then randomized to either a Savary (n = 88), Microvasive (n = 81), or Bard (n = 82) dilator. There were no significant differences between the rigid dilator or the two balloons with regard to immediate relief of dysphagia or the need for repeat dilatation at one year. Patients with moderate/severe strictures required repeat dilatation at one year twice as often as those with mild strictures. There were no significant complications reported in these patients. CONCLUSIONS: Both rigid and balloon dilators are equally effective and safe in the treatment of benign lower esophageal strictures caused by acid reflux and Schatzki rings.

Aged↗
PubMed1999

Photoelastic stress analysis of load transfer to implants and natural teeth comparing rigid and semirigid connectors.

STATEMENT OF PROBLEM: Controversy exists regarding the connection of implants to natural teeth. PURPOSE: This simulation study measured photoelastically the biologic behavior of implants. Stress transfer patterns with variable implant support and simulated natural teeth through rigid and nonrigid connection were examined under simulated functional loads. MATERIAL AND METHODS: A photoelastic model of a human left mandible edentulous distal to first premolar was fabricated having 2 screw type implants (3.75x13 mm) embedded within the edentulous area. Two fixed prosthetic restorations were fabricated with either a nonsplinted proximal contact or a soldered proximal contact, and cast precision dowel attachment between implant areas and simulated tooth. Simulated vertical occlusal loads were applied at fixed locations on the restorations. Stresses, which developed in the supporting structure, were monitored photoelastically and recorded photographically. RESULTS: The rigid connector in the 1 implant situation caused only slightly higher stresses in the supporting structure than the nonrigid connector. The distally loaded 1 and 2 implant-supported restoration produced the highest apical stresses, which occurred at the distal implant. The rigid connector demonstrated the greatest stress transfer in the 2 implant-supported restoration. CONCLUSIONS: Lower stresses apical to the tooth or implant occurred with forces applied further from the supporting abutment. Although the least stress was observed when using a nonrigid connector, the rigid connector in particular situations caused only slightly higher stresses in the supporting structure. The rigid connector demonstrated more widespread stress transfer in the 2 implant-supported restoration. Recommendations for selection of connector design should be based on sound clinical periodontal health of a tooth and the support provided by implants.

Adult↗
PubMed2002

Detection of low-molecular-mass plasma peptides in the cavernous and systemic blood of healthy men during penile flaccidity and rigidity--an experimental approach using the novel differential peptide display technology.

OBJECTIVES: To use Differential Peptide Display (DPD) technology to evaluate the patterns of low-molecular-mass peptides and small proteins in the systemic and cavernous blood taken from healthy adult male volunteers during the penile stages of flaccidity and rigidity. Results from basic research implicate a role of various peptides in the control of mammalian penile erectile tissue. Nevertheless, it is not yet known which particular peptides are essential in the regulation of penile flaccidity, tumescence, rigidity, and detumescence. METHODS: Five healthy male subjects were exposed to visual and tactile erotic stimuli to elicit penile erection. Whole blood was simultaneously aspirated from the corpus cavernosum and cubital vein during penile flaccidity and rigidity. Plasma aliquots were subjected to DPD analysis by means of matrix-assisted-laser-desorption-ionization mass mapping and electrospray-ionization quadrupole--time-of-flight mass spectrometry. RESULTS: High-resolution two-dimensional peptide mass mapping revealed differences in the systemic and cavernous plasma samples related to penile flaccidity and rigidity. Distinct signals were recognized in the cavernous but not in the systemic plasma obtained during flaccidity. These signals were not registered in the plasma samples obtained from the corpus cavernosum during rigid erection. Although one signal was identified as the blood coagulation-activating peptide XIIIa, the remaining two signals could not be related to any known peptide. These signals may represent unknown local peptidergic factors that might be involved in the regulation of penile flaccidity. CONCLUSIONS: Our study demonstrates that DPD is a feasible method for detecting differences in the cavernous and systemic blood in relation to the different functional conditions of the penile erectile tissue. Additional studies using DPD should include the analysis of blood samples taken from the cavernous meshwork of healthy subjects during penile tumescence and detumescence to establish DPD as a valuable tool in contemporary corpus cavernosum basic research.

Adult↗
PubMed1997

Influence of the method of intracavernous injection on penile rigidity: a possible pharmacokinetic explanation.

OBJECTIVES: To study whether the method of intracavernous injection of vasodilators has an effect on the clinical outcome and to explain the mechanism of possible influence. METHODS: In an open clinical study, penile rigidity after bolus injection was compared with rigidity after slow injection in 52 self-injecting, impotent patients. In 35 volunteers, venous plasma levels of intracavernosally injected drugs were followed under different injection conditions: slow injection of undiluted drug, slow injection of diluted drug, bolus injection, use of a tourniquet, or slow injection followed by squeeze of the corpora. RESULTS: Of the 52 patients, 28 reported better penile rigidity after a bolus injection than after slow injection of vasodilators. The other 24 reported no difference in rigidity. Systemic side effects did not occur, but 4 patients reported local pain after bolus injection. In the 35 volunteers, the lowest plasma levels were observed when a tourniquet was used or when a bolus injection was performed; the quickest transfer was observed after a slow injection of a low volume of the drug. CONCLUSIONS: Better rigidity was observed after bolus injection in a majority of the patients using the same dose of vasodilators. This could be due to the pharmacokinetic phenomenon of a slower drug transfer to the systemic circulatory system after a bolus than after a slow injection.

Aged↗
PubMed1991

The stability of double jaw surgery: a comparison of rigid versus wire fixation.

The subjects of this study were 35 patients who underwent simultaneous surgery for superior repositioning of the maxilla and advancement of the mandible. They were studied cephalometrically for a comparison of the postsurgical stability of two commonly used fixation techniques: (1) rigid fixation with bone plates and (2) skeletal-wire fixation. One surgeon performed the operations on all 35 patients, and both groups were studied for an average of 15 months after surgery. Results showed that, although the maxilla remained relatively stable after surgery with both fixation techniques, rigid fixation tended to improve stability, primarily by eliminating relapse in excess of 2 mm. Mandibular stability was much greater with rigid fixation: the amount of relapse of the horizontal projection of B point with this method was 6%, while in the skeletal-wire sample it was 26%. Increased rotational stability between the proximal and distal segments of the mandible appeared to be a major factor in the improved overall stability of the rigid-fixation sample. The amount of mandibular relapse was found to be correlated to the amount of advancement in the wire-fixation sample, but not in the rigid-fixation sample.

Adult↗
PubMedDate not supplied

Comparison of allograft to autograft in multilevel anterior cervical discectomy and fusion with rigid plate fixation.

BACKGROUND CONTEXT: A relatively high pseudarthrosis rate is associated with multilevel anterior cervical discectomy and fusion (ACDF). Anterior plate fixation increases fusion rate in multilevel ACDF. A debate still exists between the effectiveness of allograft versus autograft in plated multilevel ACDF. PURPOSE: To determine the efficacy of allograft versus autograft in fusion rate and clinical outcome in patients undergoing two- and three-level ACDFs with rigid anterior plate fixation. STUDY DESIGN: A retrospective radiographic and clinical review to assess fusion, risk factors and clinical outcome of 80 consecutive patients who underwent ACDF with rigid anterior plate fixation involving two and three levels with either allograft or autograft. PATIENT SAMPLE: There were 45 patients (56%) who had autogenous iliac crest tricortical grafts and 35 patients (44%) who received tricortical allograft with an average age of 49 years who were treated by multilevel ACDF with rigid anterior plate fixation at a single institution. Thirty-three Peak polyaxial (Depuy-Acromed, Rayham, MA), 26 Orion (Sofamor-Danek, Memphis, TN), 16 Atlantis (Sofamor-Danek, Memphis, TN) and 5 Synthes (Paoli, PA) anterior cervical plating systems were used. All patients underwent ACDF (61 two-level, 19 three-level) by a Smith Robinson technique. All patients had burring of the end plates, 2-mm distraction of the motion segment and graft countersunk 2 mm from the anterior vertebral border. Anterior cervical plate with unicortical screw purchase was used in all cases. Segmental screw fixation was performed in 46 patients. Soft collars were worn postoperatively for 3 to 4 weeks. OUTCOME MEASURES: Follow-up lateral neutral, flexion and extension radiographs were used to assess fusion. The radiographs were reviewed by an independent blinded observer in assessing fusion grades between autograft versus allograft. Clinical outcomes were rated excellent, good, fair and poor based on Odom's criteria. METHODS: Fusion rate and postoperative clinical outcome were assessed in 80 patients who underwent two- or three-level ACDF with rigid anterior plate fixation. Additional risk factors were also analyzed. RESULTS: Radiographic fusion was assessed in all patients (mean, 16 months). Seventy-eight patients (97.5%) achieved solid arthrodesis. Pseudarthrosis occurred in two patients who had allograft for two-level and three-level fusions. Nonsegmental screws were used in the two-level nonunion case. Postoperative dysphagia developed in one two-level nonunion patient, and revision surgery was performed in the other nonunion three-level patient. Twenty-three patients were smokers, and 26 patients had work-related injuries. Clinical outcome (mean, 20 months) was excellent in 23, good in 48 and fair in 9 patients. No statistical significance was noted between demographics, history of tobacco use, graft-type, end plate preparation technique, intermediate segmental screws, plate-type, clinical outcome of fused and nonfused patients and presence of work-related injuries (p>.05). CONCLUSIONS: A high fusion rate of 97.5% was obtained for multilevel ACDF with rigid plating with either autograft or allograft. In this study, nonunion occurred in patients with allograft but this difference was not statistically significant. Fusion was obtained in 97.8% of patients with segmental screw fixation and 97.1% with nonsegmental screw fixation. Nonsegmental screw fixation may contribute to less than adequate stability and contribute to a higher rate of nonunion, but such effects could not be discerned from this study. Excellent and good clinical outcome was noted in 88.8% of the patients. Proper patient selection and meticulous operative technique is essential to obtain high fusion rates and optimal clinical outcome, which is more important than graft type.

Adult↗
PubMed2005

Connecting rigidities of various precision attachments compared with the conical crown retained telescope.

The purpose of this investigation was to observe the connecting rigidity of various precision attachments and to compare their connecting rigidities with the conical crown retained telescope (CCT). The connecting rigidity of a retainer was assessed using the flexibility test to measure the mesial and distal end displacements. Four precision attachments were analyzed: the dovetail slide attachment beyeler, cylindrical slide attachment, Spang Stabilex and Mini SG. The CCT was used as the control. Although there were many statistically significant differences between the displacements with the various attachments, displacements when vertically loaded were very small: all mesial end displacements were within 3 microm and distal end displacements were 21.4 microm. The largest of the mesial end displacements when horizontally loaded was as large as 44.5 microm (dovetail slide beyeler), while the others were all below 16.5 microm. The same phenomena occurred with the distal end displacements when horizontally loaded: the largest was seen with the dovetail slide beyeler, followed sequentially by the Spang Stabilex, CCT, cylindrical slide, and the Mini SG. The distal displacement with the dovetail slide beyeler was as large as 75.2 microm; those with the others were all below 31.2 microm, with numerous statistically significant differences between the displacements with the various attachments. Thus, connecting rigidities of rigid precision attachments are very similar to CCT, and only the dovetail slide beyeler attachment is too weak to resist horizontal displacement force.

Adaptation, Physiological↗
PubMed2001

Electrostatics of cell membrane recognition: structure and activity of neutral and cationic rigid push-pull rods in isoelectric, anionic, and polarized lipid bilayer membranes.

Design, synthesis, and structural and functional studies of rigid-rod ionophores of different axial electrostatic asymmetry are reported. The employed design strategy emphasized presence of (a) a rigid scaffold to minimize the conformational complexity, (b) a unimolecular ion-conducting pathway to minimize the suprastructural complexity and monitor the function, (c) an extended fluorophore to monitor structure, (d) variable axial rod dipole, and (e) variable terminal charges to create axial asymmetry. Studies in isoelectric, anionic, and polarized bilayer membranes confirmed a general increase in activity of uncharged rigid push-pull rods in polarized bilayers. The similarly increased activity of cationic rigid push-pull rods with an electrostatic asymmetry comparable to that of alpha-helical bee toxin melittin (positive charge near negative axial dipole terminus) is shown by fluorescence-depth quenching experiments to originate from the stabilization of transmembrane rod orientation by the membrane potential. The reduced activity of rigid push-pull rods having an electrostatic asymmetry comparable to that in alpha-helical natural antibiotics (a positive charge near the positive axial dipole terminus) is shown by structural studies to originate from rod "ejection" by membrane potentials comparable to that found in mammalian plasma membranes. This structural evidence for cell membrane recognition by asymmetric rods is unprecedented and of possible practical importance with regard to antibiotic resistance.

Amino Acid Sequence↗
PubMed2004

Rigidity in parent-child interactions and the development of externalizing and internalizing behavior in early childhood.

Behavioral rigidity is a common feature of many psychopathologies, yet the association between rigidity and the development of childhood psychopathology has not been studied. State space grids (a dynamic systems [DS] method) were used to examine the relation between rigidity in parent-child interactions and childhood externalizing and internalizing problems. High-risk kindergarten children (n = 240) and their parents were observed for 2 hr engaging in a variety of tasks that were expected to elicit a range of affect. State space grid analysis of the observational data revealed an association between rigidity in parent-child interactions and child externalizing behavior problems in the fall and spring of kindergarten and 1st grade, and with growth in those problems over time. Rigidity was associated with concurrent levels and with chronic high-level internalizing problems. Strengths and limitations of the new DS methodology in relation to understanding child psychopathology are discussed.

Adult↗
PubMed1999

A comparison of visual performance between a rigid PMMA and a foldable acrylic intraocular lens.

PURPOSE: To examine post-operative visual outcomes when using micro-incision surgery and a three-piece, foldable acrylic intraocular lens (IOL) and when using small-incision surgery and a one-piece, rigid polymethyl-methacrylate (PMMA) IOL. METHODS: Phacoemulsification and IOL implantation was conducted by one surgeon on 86 subjects (aged 50-89 years) with cataracts. Of these subjects, 67 completed the study. Subjects were implanted either with a foldable IOL (n = 38) or a rigid IOL (n = 29). Best corrected Snellen visual acuity and contrast sensitivity (2-28 cycles/degree) were measured approximately 2 months post-operatively. Comparisons were made between the pseudophakic groups and an additional group of 28 age-matched, normal subjects (aged 58-81 years). Non-parametric (Kruskal-Wallis and Mann-Whitney U) as well as parametric (ANOVA and Pearson) statistics tests were used in the analysis of results. RESULTS: All pseudophakes had corrected visual acuity of 6/9 or better. There were no significant differences in visual acuity (Kruskal-Wallis, p = 0.61) or contrast sensitivity (ANOVA, p = 0.33) between the three groups. The mean residual refractive error of the foldable IOL group was hypermetropic in comparison with the rigid IOL group but not significant at the 99% level of probability (Mann-Whitney U, p = 0.02). There was no significant difference in astigmatism between the groups. CONCLUSIONS: Implanting a foldable acrylic IOL gave no post-operative benefit in visual acuity and contrast sensitivity to pseudophakes over a less expensive rigid PMMA IOL, within this post-operative period. This study did not provide a comparison between the two lenses regarding post-operative complications, in particular the important long-term complication of posterior capsular opacification (PCO). Until and if any particular advantage of a given IOL in reduced incidence of PCO is confirmed, it appears more economical to implant the conventional rigid PMMA IOL using small-incision surgery.

Acrylic Resins↗
PubMed1998

Rigidity and retention of root canal posts.

OBJECTIVE: To test the rigidity and the retention into roots of parallel root canal posts, one a spiral vented titanium post and the other a spiral serrated, hollow, stainless steel post. A serrated, stainless steel post was used as the control. MATERIALS AND METHODS: A three-point bending test was used to test rigidity. To test retention, ten posts of each type were cemented into the roots of extracted teeth with a resin cement and the tensile loads required to remove them were compared using Student's t and Mann-Whitney U tests. RESULTS: The serrated stainless steel posts were significantly more rigid than either of the other types. The titanium posts and the stainless steel hollow posts were not significantly different in rigidity. The serrated, stainless steel posts were significantly better retained than either of the other types. The titanium posts showed greater retention than the hollow posts. CONCLUSIONS: Within the limits of the study the stainless steel, serrated posts were superior to the two newer types in terms of rigidity and retention into roots.

Cementation↗
PubMed2001

A randomised trial of flexible versus rigid nasendoscopy in outpatient sinonasal examination.

Nasendoscopy is used extensively in ENT clinics both as a diagnostic tool and for local postoperative care. Both flexible and rigid fibreoptic scopes are available for the purpose of sinonasal examination. A prospective study of a flexible versus rigid endoscope was carried out, randomly assigning one type of scope to each nostril of 56 patients presenting to clinic with sinonasal symptomatology. Patients awarded each type of scope a pain score on an analogue scale, according to the level of discomfort experienced, and the operator noted the number of structures seen. Significantly more structures were visualized with the rigid scope than the flexible scope (P = 0.05). The pain scores were similarly in favour of the rigid scope, showing a trend to less discomfort. The rigid nasendoscope is the scope of choice for sinonasal examinations in the outpatient clinic based on these data.

Adult↗
PubMed2001

Economic costs of cataract surgery using a rigid and a foldable intraocular lens.

Optimal delivery of healthcare requires consideration of various costs. A foldable intraocular lens (IOL) is more expensive than an equivalent rigid IOL. However, surgical and post-operative costs may make a foldable IOL economically preferable. We compared the economic costs of cataract surgery plus implantation of a foldable IOL with implantation of a rigid IOL. Prospective audit of the clinical records of 82 pseudophakes; 39 implanted with a rigid IOL and 43 implanted with a foldable IOL by one surgeon. Average follow-up periods were 25 +/- 7 months and 23 +/- 5 months respectively. There was no difference between the two groups for the follow-up period (P = 0.55), number of post-operative complications (P = 0.25) or cost of post-operative visits (P = 0.83). The cost of single-use theatre equipment was greater for the rigid-IOL group (P= 0.0001). The total identified cost per patient was greater for the foldable-IOL group (P = 0.0001). Despite possible technical advantages, implantation of the foldable IOL did not provide an economic benefit, either in the initial cost or in the costs of post-operative care. Over the 2-year period, implanting with the rigid IOL cost, on average, Pound Sterling57 less per patient. Despite this economic difference, a cost-benefit analysis is required, since other factors may be more important.

Ambulatory Surgical Procedures↗
PubMed2001

[A new rigid bronchoscope with a measuring tube for pressure and capnometry].

BACKGROUND: Pulmonary gas exchange under jet ventilation is usually controlled by pulse-oxymetry and blood gas analysis. Capnometry is not common in clinical use. Rigid bronchoscopes with pressure measurements are not known. Our aim was the development of a rigid bronchoscope with a built-in tube for the online measurement of airway pressure and gas composition. METHODS: We measured the distribution of inspiratory pressure under jet ventilation over the length inside a 8 x 400 mm rigid bronchoscope in a lung model and in patients. A measuring tube was constructed for obtaining representative values of airway pressure and capnometry. Using a prototype of a new rigid bronchoscope with the built-in measuring tube (R. Wolf Company, Knittlingen, Germany) inspiratory pressure and expiratory CO2 were measured during interventional bronchoscopy. The measuring tube was connected to the pressure control port of the jet ventilator. We applied jet ventilation with frequencies of 10 to 12 pulses per minute. RESULTS: The inspiratory pressure reaches after 10 cm distally the instrumental port a significant constant plateau. Via the built-in measuring tube representative measurement of pressure and gas can be made there. The correlation between arterial CO2 (paCO2) and expiratory CO2 (petCO2) was excellent (r = 0.96). To maintain normocapnia in 25 patients undergoing interventional bronchoscopy, the jet pressure had to be adjusted to values between 0.5 and 3.5 bar (median 2.5 bar). The responding inspiratory pressure varied from 3 to 25 mbar (median 15 mbar). A flexible bronchoscope in the working channel raises the airway pressure from 18 to 23 mbar. The automatic interruption of the jet-pulses by connecting the measuring tube to the pressure control port of the ventilator in order to prevent a barotrauma was found feasible. CONCLUSIONS: Simultaneous online control of airway pressure and gas is possible with the new rigid bronchoscope. Pressure depending jet ventilators can be controlled via the measuring tube to minimise the risk of barotrauma.

Airway Resistance↗