In silico investigation of sneezing in a full real human upper airway using computational fluid dynamics method

BACKGROUND AND OBJECTIVE

Sneezing is one of the most critical conditions that can occur in the human upper airway. As some reports confirm the injury to the human upper respiratory airway while sneezing. Therefore, the accurate study of the distribution of pressure and velocity in this case is of great importance.

METHODS

In the present study, using a real human upper airway model, the pressure and velocity of the airflow generated in the tract during the sneezing have been investigated. Also, considering the results from a spirometer device as a boundary condition in the simulation process, the calculations have become reliable.

RESULTS

According to the results, during sneezing, taking into account that the average outlet flow rate from the mouth is 4.79 L/s, the velocity of outlet airflow from the mouth and nose reaches 5.3 and 8.4 m/s, respectively. These values were 11.5 and 19, respectively, when the desired maximum flow rate was 10.58 L/s. It can be concluded that the increasing of trachea flow rate, leads to higher percentage of the outlet flow rate from the nose . The highest average pressure and velocity have been occurred in the trachea. Among other salient results of this report, increased average static pressure of larynx to approximately 10 kPa can be pointed which indicates that this area is critical so that the thyroid cartilage defect is likely to occur. It is also noteworthy that the increase of speed at nasopharynx is up to 125 m/s so that the cross-section changing in this area leads the fluid acts as a jet flow. Due to the specific geometry of the nasal cavity, some streams similar to poor shocks are formed, these shocks get stronger by increasing of the flow rate. The thyroid cartilage and nasal cavity are exposed to maximum static pressure extremums, respectively.

CONCLUSIONS

We introduced a model simulating a normal sneezing for two cases using a healthy 30-year-old male person. We believe that the model should be applied for different persons and an atlas of data could be obtained from different cases. This may help the medical system to have more data about the sneezing process.

The effects of heated humidification to nasopharynx on nasal resistance and breathing pattern

Background

Mouth breathing could induce not only dry throat and eventually upper respiratory tract infection, but also snoring and obstructive sleep apnea, while nasal breathing is protective against those problems. Thus, one may want to explore an approach to modify habitual mouth breathing as preferable to nasal breathing. The aim of this study was to investigate the physiological effects of our newly developed mask on facilitation of nasal breathing.

Methods

Thirty seven healthy male volunteers were enrolled in a double blind, randomized, placebo-controlled crossover trial. Participants wore a newly developed heated humidification mask or non-heated-humidification mask (placebo) for 10-min each. Subjective feelings including dry nose, dry throat, nasal obstruction, ease to breathe, relaxation, calmness, and good feeling were asked before and after wearing each mask. In addition, the effects of masks on nasal resistance, breathing pattern, and heart rate variability were assessed.

Results

Compared with the placebo mask, the heated humidification mask improved all components of subjective feelings except for ease to breathe; moreover, decreased nasal resistance and respiratory frequency accompanied a simultaneous increase in a surrogate maker for tidal volume. However, use of the heated humidification mask did not affect heart rate variability

Conclusion

Adding heated humidification to the nasopharynx could modulate breathing patterns with improvement of subjective experience and objective nasal resistance.

Creation of an idealized nasopharynx geometry for accurate computational fluid dynamics simulations of nasal airflow in patient-specific models lacking the nasopharynx anatomy

Virtual surgery planning based on computational fluid dynamics (CFD) simulations has the potential to improve surgical outcomes for nasal airway obstruction patients, but the benefits of virtual surgery planning must outweigh the risks of radiation exposure. Cone beam computed tomography (CT) scans represent an attractive imaging modality for virtual surgery planning due to lower costs and lower radiation exposures compared with conventional CT scans. However, to minimize the radiation exposure, the cone beam CT sinusitis protocol sometimes images only the nasal cavity, excluding the nasopharynx. The goal of this study was to develop an idealized nasopharynx geometry for accurate representation of outlet boundary conditions when the nasopharynx geometry is unavailable. Anatomically accurate models of the nasopharynx created from 30 CT scans were intersected with planes rotated at different angles to obtain an average geometry. Cross sections of the idealized nasopharynx were approximated as ellipses with cross-sectional areas and aspect ratios equal to the average in the actual patient-specific models. CFD simulations were performed to investigate whether nasal airflow patterns were affected when the CT-based nasopharynx was replaced by the idealized nasopharynx in 10 nasal airway obstruction patients. Despite the simple form of the idealized geometry, all biophysical variables (nasal resistance, airflow rate, and heat fluxes) were very similar in the idealized vs patient-specific models. The results confirmed the expectation that the nasopharynx geometry has a minimal effect in the nasal airflow patterns during inspiration. The idealized nasopharynx geometry will be useful in future CFD studies of nasal airflow based on medical images that exclude the nasopharynx.

Nasopharyngeal temperature measurement in sheep during general anesthesia

The aim of this study was to compare nasopharyngeal and esophageal temperature measurements in anesthetized sheep with a range of fresh gas flows (1 to 6 L/min) through the breathing system. Data were compared using a Bland-Altman plot and correlation coefficients, and error measures were calculated. One hundred and ninety-five sets of data were collected from 20 sheep weighing 41 kg (31 to 51.5 kg). The bias (95% limit of agreement), correlation coefficient, and absolute error for nasopharyngeal compared to esophageal temperature were 0.04°C (-0.77°C to 0.85°C), 0.92, and 0.29°C ± 0.29°C, respectively. The percentage of nasopharyngeal readings within 0.5°C of the esophageal temperature was 77.44%. The error did not significantly increase with increasing fresh gas flow. Nasopharyngeal temperature measurement is suitable for estimation of esophageal temperature during general anesthesia of sheep when the fresh gas flow through the breathing system is between 1 and 6 L/min.

Correlations between videoendoscopy and sonotubometry of eustachian tube opening during a swallow

OBJECTIVES/HYPOTHESIS

Describe the relationship between the magnitude of eustachian tube (ET) dilation during swallowing observed on transnasal videoendoscopy and quantified by sonotubometry.

STUDY DESIGN

Descriptive observational study.

METHODS

Simultaneous transnasal videoendoscopic and sonotubometric recordings were done on 33 adults with no middle ear disease. Briefly, microphones were placed in the ear canals, a 45° telescope introduced through one side of the nose to visualize and record ipsilateral ET movements, and the probe from a sound generator placed in the opposite nostril. At a generated nasopharyngeal sound level, ET movements and ipsilateral microphone signals were continuously recorded while the subject performed a series of three swallows. For each swallow, relational movements among ET structures observed on video recordings and characteristics of the sonotubometry signal envelope at the ear canal were quantified at three times: swallow onset (T1), maximum soft-palate elevation (T2), and maximum ET luminal dilation (T3).

RESULTS

A total of 99 swallows were analyzed. The average medial rotation of the ET cartilage and lateral wall over the T1-T2 interval were -32.7 ± 14.9° and 7.2 ± 25.1°, and over the T2-T3 interval were 4.6 ± 7.7° and 6.2 ± 14.6°, respectively. The transtubal sound transmission during a swallow peaked at an amplitude of 30.5 ± 35.7 mV during the 572.5 ± 292.6 ms of elevated sound-pressure time. Correlational analysis documented significant linear associations between the relational measures of ET component movements from videoendoscopy and the signal envelope measures from sonotubometry.

CONCLUSIONS

There is a direct linear relationship between the degree of ET luminal dilation visualized on videoendoscopy and represented in the sonotubometry signal envelope.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:2778-2784, 2016.

Three-Dimensional Evaluation of the Upper Airway Morphological Changes in Growing Patients with Skeletal Class III Malocclusion Treated by Protraction Headgear and Rapid Palatal Expansion: A Comparative Research

Objective

The aim of this study was to evaluate the morphological changes of upper airway after protraction headgear and rapid maxillary expansion (PE) treatment in growing patients with Class III malocclusion and maxillary skeletal deficiency compared with untreated Class III patients by cone-beam computed tomography (CBCT).

Methods

Thirty growing patients who have completed PE therapy were included in PE group. The control group (n = 30) was selected from the growing untreated patients with the same diagnosis. The CBCT scans of the pre-treatment (T1) and post-treatment (T2) of PE group and the control group were collected. Reconstruction and registration of the 3D models of T1 and T2 were completed. By comparing the data obtained from T1, T2 and control group, the morphological changes of the upper airway during the PE treatment were evaluated.

Results

Comparing with the data from T1 group, the subspinale (A) of maxilla and the upper incisor (UI) of the T2 group were moved in the anterior direction. The gnathion (Gn) of mandible was moved in the posterior-inferior direction. The displacement of the hyoid bone as well as the length and width of dental arch showed significant difference. The volume and mean cross-sectional area of nasopharynx, velopharynx and glossopharynx region showed significant difference. The largest anteroposterior/the largest lateral (AP/LR) ratios of the velopharynx and glossopharynx were increased, but the AP/LR ratio of the hypopharynx was decreased. In addition, the length and width of the maxillary dental arch, the displacement of the hyoid bone, the volume of nasopharynx and velopharynx, and the AP/LR ratio of the hypopharynx and velopharynx showed significant difference between the data from control and T2 group.

Conclusion

The PE treatment of Class Ⅲ malocclusion with maxillary skeletal hypoplasia leads to a significant increase in the volume of nasopharynx and velopharynx.

Core temperature--the intraoperative difference between esophageal versus nasopharyngeal temperatures and the impact of prewarming, age, and weight: a randomized clinical trial

Unplanned perioperative hypothermia is a well-known complication to anesthesia. This study compares esophageal and nasopharyngeal temperature measured in the same patient for a period of 210 minutes of anesthesia. Forty-three patients undergoing colorectal surgery were randomly assigned in 2 groups, with or without a prewarming period (group A = prewarming [n = 21] or group B = no prewarming [n = 22]). Demographics were similar in both groups. Mean temperatures at 210 minutes were statistically different between the groups at both sites of measurement. Esophageal temperature in group A was 36.5 ± 0.6 vs 35.8 ± 0.7 in group B (P = .001), and nasopharyngeal temperature was 36.7 ± 0.6 and 36.0 ± 0.6 in group A and group B, respectively (P = .002). A negative correlation was found between esophageal temperature and age (r2 = -.381, P < .012). Esophageal temperature was different with respect to BMI below or above 25. The temperatures were 35.81 ± 0.66 in the lower BMI group vs 36.46 ± 0.59 (P < .001). These results demonstrate a difference between the 2 measurement techniques and that prewarming, age and BMI have an impact on measured temperatures.

The influence of nasopharyngeal patency on the morphology of nasomaxillary complex

OBJECTIVE

The aim of this study was to compare the nasomaxillary complex in subjects with nasopharyngeal obstruction symptoms and the group with normal nasopharyngeal patency.

MATERIALS AND METHODS

The study analyzed lateral cephalograms and dental plaster casts of 229 orthodontic subjects from the orthodontic clinic, i.e. 129 (56%) females and 100 (44%) males, age range of 6-30 years (mean age = 13.79). The analysis of radiographs and cephalometric measurements were performed using Orto-TestPor-ZPaluch software. The study population examined according to the stage of cervical vertebral maturation was divided into three sub - groups [the CVM A group consisted of 57 (24.9%) subjects, the CVM B group consisted of 85 (37.1%) subjects and the CVM C group consisted of 87 (38%) subjects].

RESULTS

In the youngest age group with less than 50% airway patency, smaller values of SNA angle were observed together with diminished anterior palatal width compared with the non-obliterated group. The decrease in the area of the nasomaxillary complex and the decrease in posterior palatal width were observed in the oldest age group with less than 50% airway patency as compared to the subjects with normal patency.

CONCLUSIONS

The nasomaxillary complex morphology in subjects with decreased nasopharyngeal patency pre - disposes to air flow impediment through nasal respiratory passage. Non-extraction treatment of the upper dental arch and possible maxillary expansion can be considered when orthodontic treatment is planned in subjects with decreased patency of < 50% and CVM A.

[Prophylaxis of acute respiratory infections in children's collectives: results of treatment with nasal and nasopharyngeal irrigation]

The aim of this paper is to report the results of a multicenter open randomized clinical study of the efficacy of nasal and nasopharyngeal irrigation for the prevention of seasonal morbidity due to acute respiratory infections (ARIs) in the groups of preschool and school children. A total of 2386 children attending secondary schools and 519 ones attending kindergartens were examined. The study has demonstrated that irrigation of the nasal cavity and nasopharynx efficaciously reduces (by 2.4-3.2 times) the morbidity due to ARIs in organized children's collectives throughout the entire length of the epidemiological period; moreover, it improves the clinical course of ENT organ diseases and bronchial asthma.

Functional anatomy of the Eustachian tube

The Eustachian tube (ET) is divided in 3 portions: a bony portion, a cartilaginous portion, and a junctional portion. From an anatomical-functional point of view, the bony portion of ET is the region of ventilation and clearance of secretions, and is lined by pseudostratified, ciliated, columnar epithelium, with an anti-gravitational direction of the drainage. The ET in the bony portion is in a state of forced opening. The cartilaginous portion is instead the heart of this dynamic system tube, because the mechanism of opening and closing of the tube is at this level. ET is normally closed, and it opens only during swallowing, being essential for good functioning of the middle ear, because it provides ventilation from the nasopharynx to the middle ear, and, at the same time, clearance of secretions from the middle ear-mastoid unit to the nasopharynx. Moreover, the ET protects the middle ear against nasopharyngeal pressure variations, ascending secretions, and microorganisms. The ability to develop all these functions makes the tube a complex organ.

Fatal pneumoperitoneum caused by nasopharyngeal oxygen delivery after transoesophageal echocardiography for cardiac surgery

We report a case of fatal post-operative pneumoperitoneum in a patient who had undergone urgent mitral valve surgery. In the absence of a proven cause of the pneumoperitoneum (refusal by the family of an autopsy), we can only propose a hypothesis for its origin. The most probable one is that forceful or sustained retrograde flexion of the transoesophageal echocardiographic probe created a lower oesophagus or gastric rupture and that oxygen flow administered by the nasal cannula went straight to the abdominal cavity, leading to tension pneumoperitoneum.

[Nasopharyngeal carcinoma study: introduction and multidisciplinary perspective]

Nasopharynx is a particular anatomic structure, located between the respiratory and digestive systems, and it is the geographic centre of all otorinolaringologic pathologies. Numerous filogenic, ontogenic and embryogenic factors contribute to the anatomic and physiologic structure of nasopharynx. These factors may directly contribute to the development of several pathologies, as the embryogenic pathology, or even in an indirect way, through the interaction with the environment, as the inflammatory and neoplastic pathologies, of which the nasopharyngeal carcinoma acquires great significance. The objective of this study was to endorse the importance of a multidisciplinary approach in the study of nasopharynx, contributing to a wider knowledge about the different kinds of diseases associated with this anatomic structure.

A randomised controlled trial of the electric heating pad vs forced-air warming for preventing hypothermia during laparotomy

A randomised controlled trial was conducted to compare the efficacy of upper body forced-air warming (Bair Hugger, Augustine Medical model 500/OR, Prairie, MN) with that of an electric heating pad (Operatherm 202, KanMed, Bromma, Sweden) for maintenance of intra-operative body temperature in 60 patients undergoing laparotomy under general anaesthesia. The nasopharyngeal temperature was recorded throughout the operative period. The mean (SD) final temperatures were 36.2 (0.4) degrees C with forced-air warming and 35.5 (1.0) degrees C with electric heating pad (p < 0.01). Upper body forced-air warming is more effective than the heating pad for maintenance of body temperature during laparotomy.

E-cadherin is a receptor for the common protein pneumococcal surface adhesin A (PsaA) of Streptococcus pneumoniae

Streptococcus pneumoniae (Pnc) binds to nasopharyngeal (NP) epithelial cells in the first steps of nasopharyngeal carriage and colonization through bacterial adhesins. The pneumococcal surface adhesin A (PsaA) has previously been reported to play a significant role in pneumococcal adherence and colonization. Identification of a receptor for PsaA on human epithelium will aid in understanding the pathogenesis of this bacterium. Using recombinant PsaA covalently bound to fluorescent spheres (fluospheres), we show PsaA binds to NP cells through interaction with the human cellular receptor, E-cadherin. SDS-PAGE silver stain analysis demonstrates binding of PsaA to E-cadherin. Recombinant human E-cadherin binds to and blocks PsaA-coated fluospheres and whole transparent bacteria from adhering to NP cells, but does not block a Pnc PsaA(-) mutant. Recombinant E-selectin and human alpha(5)beta(1) integrin did not bind to or block PsaA-coated fluosphere adherence to NP cells. Likewise, if NP cells were preincubated with anti-E-cadherin antibody, there was a significant decrease (46%, P=0.05) in PsaA-coated fluosphere adherence to the cells. Additionally, when using E-cadherin transfected cells, we observed PsaA-coated fluospheres bind more efficiently to cells which express E-cadherin. This work identifies E-cadherin as a receptor on human epithelial cells for the pneumococcal surface adhesin, PsaA.

Uptake of microparticles into the epithelium of human nasopharyngeal lymphoid tissue

The M cells of nasopharyngeal lymphoid tissue (NALT) have been considered to play an important role for vaccine delivery systems in humans. A number of investigations have reported particle uptake data in NALT of rodents. However, there have been no reports indicating any involvement of the nasopharyngeal lymphoid tissue in human vaccination. In the present study, we investigated whether the epithelium of human adenoid tissues might incorporate fluorescent microparticles using electron and fluorescent microscopy. The dissected adenoid tissues were incubated with various sizes and concentrations of fluorescent microparticles for 120 min at 37 degrees C. Furthermore, the effect of surface coatings of microparticles with cations on the uptake into the epithelium of adenoid tissues was investigated. Transmission electron microscopy revealed that microparticles were taken up by the M cells of human nasopharyngeal lymphoid tissues. The NALT-M cells showed greater uptake of the smallest particles, 0.2 microm in diameter, than those of 0.5, 1.0, or 2.0 microm diameter. It was also revealed that surface coatings with poly-L: -lysin or chitosan resulted in efficient uptake into the NALT. These results indicate that nasal administration of antigenic microparticles, which were coated with cationic materials, probably leads to a useful method of transnasal vaccination against respiratory and intestinal infections in humans.

Mechanical effects of genioglossus muscle stimulation on the pharyngeal airway by MRI in cats

To examine the regional mechanical effects of selective genioglossus muscle activation on pharyngeal airway size and function, magnetic resonance images of the pharyngeal airway were obtained in five paralyzed, anesthetized cats over a range of positive and negative pressures in an isolated, sealed upper airway. When all results across pressure levels and pharyngeal regions were analyzed, genioglossus stimulation significantly increased the cross-sectional area (CSA) of the nasopharyngeal airway. Within specific regions, stimulation tended toward significantly increasing cross-sectional airway area in the mid-nasopharynx. Despite its dilating effect, genioglossus muscle stimulation did not alter compliance in the nasopharyngeal airway, as evidenced by the similar slopes of the pressure versus cross-sectional area relationships with and without stimulation. Finally, airway shape in the mid pharynx became more circular with either increased airway pressure or genioglossus stimulation. The results indicate that selective stimulation of the genioglossus muscle dilates the nasopharynx and provide evidence that stimulation of the genioglossus alone does not alter airway compliance.

The anterior ethmoidal nerve is necessary for the initiation of the nasopharyngeal response in the rat

Stimulation of the nasal passages with ammonia vapors can initiate a nasopharyngeal response that resembles the diving response. This response consists of a sympathetically mediated increase in peripheral vascular resistance, parasympathetically mediated bradycardia and an apnea. The current study investigated the role of the anterior ethmoidal nerve (AEN) in the nasopharyngeal response in the rat, as it is thought that the AEN provides the main sensory innervation of the nasal passages. When both AENs were intact, nasal stimulation caused significant bradycardia, hypertension, and apnea and produced Fos label ventrally within the ipsilateral medullary dorsal horn (MDH) and paratrigeminal nucleus just caudal to the obex. This labeling presumably represents activation of second-order trigeminal neurons. When only one AEN was intact, the nasopharyngeal response was slightly attenuated, and a similar pattern of Fos labeling was only seen in the trigeminal nucleus ipsilateral to the intact AEN. The trigeminal labeling contralateral to the intact AEN was significantly reduced. When both AENs were cut, the nasopharyngeal response to nasal stimulation consisted of only a slight apnea and an increase in arterial pressure; the resultant Fos labeling within the trigeminal nucleus was significantly reduced. Cutting both AENs but not stimulating the nasal passages also produced some Fos labeling within the trigeminal nucleus. These findings suggest that a single AEN can provide sufficient afferent input to initiate the cardiorespiratory changes consistent with the nasopharyngeal response. We conclude that the AEN provides a unique afferent contribution that is capable of producing the diving response.

Residual air in the venous cannula increases cerebral embolization at the onset of cardiopulmonary bypass

OBJECTIVE

When the right atrium (RA) cannula is connected to the venous return line of the cardiopulmonary bypass (CPB) circuit, air is often introduced. Air in the venous cannula may increase cerebral air embolization at initiation of CPB despite the arterial line filter. We measured the volume of air present in the venous cannula after cannulation of the RA. Transcranial Doppler quantified emboli as high-intensity transient-signals (HITS) in both middle-cerebral arteries (MCA) at the beginning of CPB.

METHODS

After RA cannulation, the air column in the venous line was measured and the total volume calculated using the known lumen diameter. CPB onset was defined as the instant when the CPB machine started moving the patient's blood from the RA into the venous reservoir. Starting from CPB onset, HITS were counted: (a) until completion of the first minute on CPB (1-min count) and (b) until aortic cross clamping (pre-clamping count).

RESULTS

We studied 135 patients during coronary artery bypass surgery operated on by 10 cardiac surgeons. HITS during onset of CPB were detected in 95% of patients. Median counts were 10 HITS (25th, 75th percentiles: 3, 26) at 1-min and 21 HITS (8, 51) during pre-clamping. A significant correlation was found between the volume of air in the venous cannula and the HITS counts (r=0.524, p<0.0001). Absence of retained air was associated with lower HITS counts [3 HITS (1, 11)] compared with any amount of air [13 HITS (4, 29), p=0.002)]. The volume of air in the venous cannula, the MCA mean blood flow velocity and the pre-clamping time were the only independent predictors of the pre-clamping HITS counts (p<0.001).

CONCLUSION

Air in the venous cannula can result in HITS in the MCA. Minimizing the volume of air introduced into the venous cannula after cannulation of the RA can decrease cerebral air embolization at the beginning of CPB.

Study of the auditory tube by ventilation scintigraphy with technetium-99m

The two essential regulating mechanisms of the middle ear pressure are the trans-mucosal gas exchange in the middle ear and the ventilation function of the eustachian tube (ET). The physiological mechanism of these both functions is not yet clear. The purpose of this study was to evaluate the role of the ET pressure equilibrium function by ventilation scintigraphy with technetium-99m. The rabbit animal model in vivo was used to study the presence and role of the ventilation of the tympanic cavity via auditory tube. The obtained results did not show any ventilation function of the ET despite active opening by muscle movement. In our experience, ventilation scintigraphy with technetium-99m is not a reliable method to study the auditory tube pressure equilibrium function in physiological conditions.

Effects of angiotensin II on autonomic components of nasopharyngeal stimulation in male conscious rabbits

Angiotensin II (ANG II) is known to activate central sympathetic neurons. In this study we determined the effects of ANG II on the autonomic components of the cardiovascular responses to stimulation of nasopharyngeal receptors with cigarette smoke. Experiments were carried out in conscious New Zealand White rabbits instrumented to record arterial pressure and heart rate. Rabbits were exposed to 50 ml of cigarette smoke before and after subcutaneous osmotic minipump delivery of ANG II at a dose of 50 ng.kg(-1).min(-1) for 1 wk in one group and intracerebroventricular (icv) infusion at a dose of 100 pmol/min for 1 h in a second group. The responses were compared before and after heart rate was controlled by pacing. Autonomic components were evaluated by intravenous administration of atropine methyl bromide (0.2 mg/kg) and prazosin (0.5 mg/kg). ANG II given either systemically or icv significantly blunted the pressor response to smoke (P < 0.05) when the bradycardic response was prevented. This blunted response was not due to an absolute increase in baseline blood pressure after ANG II infusion (71.64 +/- 11.6 vs. 92.1 +/- 19.8 mmHg; P < 0.05) because normalization of blood pressure with sodium nitroprusside to pre-ANG II levels also resulted in a significantly blunted pressor response to smoke. The effect of smoke was alpha(1)-adrenergic receptor-mediated because it was essentially abolished by prazosin in both the pre- and the post-ANG II states (P < 0.05). These results suggest that elevations in central ANG II reduce the sympathetic response to smoke in conscious rabbits. This effect may be due to an augmentation of baseline sympathetic outflow and a reduction in reflex sensitivity similar to the effect of ANG II on baroreflex function.

Premature infants are less capable of maintaining thermal balance of head and body with increases of thermal environment than with decreases

We investigated whether premature infants nursed at the upper range of normal body temperature are more capable of maintaining their nasopharyngeal and rectal temperature when exposed to a 1 degrees C increase or a 1 degrees C decrease of incubator temperature. In a randomized controlled trial, premature infants were exposed to a 1 degrees C increase (T + 1 degrees C; n = 10), or to a 1 degrees C decrease (T - 1 degrees C; n = 10) of incubator temperature. Nasopharyngeal, rectal, and skin temperatures as well as heat flux at various sites, heart rate, and activity were measured over a 6-hour period. The absolute changes in core temperatures, Tnasoph and Trectal, were significantly greater in the T + 1 degrees C compared with T - 1 degrees C (T + 1 degrees C versus T - 1 degrees C: Tnasoph 0.44 +/- 0.31 degrees C and 0.18 +/- 0.14 degrees C respectively; p < 0.001; T(rectal) 0.43 +/- 0.30 degrees C and 0.25 +/- 0.10 degrees C, respectively; p < 0.01) when exposed to the increase or decrease in incubator temperature. Premature infants are less able to cope with increases in incubator temperature given that rectal and nasopharyngeal temperature change more when environmental temperature is increased.

Brain-stem components of high-frequency somatosensory evoked potentials are modulated by arousal changes: nasopharyngeal recordings in healthy humans

OBJECTIVE

Until now, the demonstration that early components of high-frequency oscillations (HFOs) evoked by electrical upper limb stimulation are generated in the brain-stem has been based on the results of scalp recordings. To better define the contribution of brain-stem components to HFOs building, we recorded high-frequency somatosensory evoked potentials (SEPs) in 6 healthy volunteers by means of a nasopharyngeal (NP) electrode. Moreover, since HFOs are highly susceptible to arousal fluctuations, we investigated whether eyes opening can influence HFOs at this level.

METHODS

We recorded right median nerve SEPs from the ventral surface of the medulla by means of a NP electrode as well as from the scalp, in 6 healthy volunteers under two different arousal states (eyes opened versus eyes closed). SEPs have been further analyzed after digital narrow bandpass filtering (400-800 Hz).

RESULTS

NP recordings demonstrated in all subjects a well-defined burst, occurring in the same latency window of the low-frequency P13-P14 complex. Eyes opening induced a significant amplitude increase of the NP-recorded HFOs, whereas scalp-recorded HFOs as well as low-frequency SEPs remained unchanged.

CONCLUSIONS

Our findings demonstrate that slight arousal variations induce significant changes in brain-stem components of HFOs. According to the hypothesis that HFOs reflect the activation of central mechanisms, which modulate sensory inputs depending on variations of arousal state, our data suggest that this modulation is already effective at brain-stem level.

Cough, expiration and aspiration reflexes following kainic acid lesions to the pontine respiratory group in anesthetized cats

The importance of neurons in the pontine respiratory group for the generation of cough, expiration, and aspiration reflexes was studied on non-decerebrate spontaneously breathing cats under pentobarbitone anesthesia. The dysfunction of neurons in the pontine respiratory group produced by bilateral microinjection of kainic acid (neurotoxin) regularly abolished the cough reflexes evoked by mechanical stimulation of both the tracheobronchial and the laryngopharyngeal mucous membranes and the expiration reflex mechanically induced from the glottis. The aspiration reflex elicited by similar stimulation of the nasopharyngeal region persisted in 73% of tests, however, with a reduced intensity compared to the pre-lesion conditions. The pontine respiratory group seems to be an important source of the facilitatory inputs to the brainstem circuitries that mediate cough, expiration, and aspiration reflexes. Our results indicate the significant role of pons in the multilevel organization of brainstem networks in central integration of the aforementioned reflexes.

Core temperature monitoring with new ventilatory devices

Widespread use of new airway devices, such as the laryngeal mask airway (LMA) and the cuffed oropharyngeal airway (COPA), preclude measuring core temperature in the distal esophagus. Therefore, we tested the hypothesis that core temperature measured with a thermocouple positioned on a LMA or COPA is sufficiently accurate and precise for clinical use. Temperatures were recorded from thermocouples positioned on the cuffs of LMAs or COPAs in 36 patients scheduled for prolonged orthopedic surgery or therapeutic hyperthermia for cancer. These temperatures, recorded at 15-min intervals, were compared with simultaneously obtained nasopharynx and tympanic membrane temperatures. Data were compared by linear regression and the bias calculated. Temperatures measured on the LMA correlated well with both nasopharyngeal (r(2) = 0.94) and tympanic membrane (r(2) = 0.94) temperatures. Temperatures measured on the COPA also correlated well with those on the nasopharynx (r(2) = 0.97) and tympanic membrane (r(2) = 0.96). The fraction of temperatures that differed from nasopharynx temperature by more than +/-0.5 degrees C was 8% with LMA and 11% with COPA; the fraction of temperatures that differed from tympanic temperature by more than +/-0.5 degrees C was 7% with LMA and 10% with COPA. These results suggest that body temperature measured from the cuffs of COPA or LMAs is sufficiently accurate for routine clinical use.

IMPLICATIONS

Temperatures measured on airway devices correlated well with independent measurements of core body temperature. Thus, body temperature measured on the cuffs of airway devices is sufficiently accurate for routine use.

Electrocardiographic changes associated with the nasopharyngeal reflex in conscious rabbits: vago-sympathetic co-activation

Electrocardiographic responses were assessed in conscious rabbits when the nasopharyngeal reflex was elicited by inhalation of formaldehyde vapour. There was a profound fall in heart rate (224+/-5 to 64+/-4 beats per min (bpm)) associated with abnormal or absent P-waves. There were no changes in the QRS complex. The R-T interval (control value 118+/-4 ms) was initially shortened to 107+/-3 ms and then prolonged to 130+/-4 ms. Heart rate and P-wave changes were prevented by muscarinic cholinergic blockade with methylscopolamine. The R-T shortening was reduced by 79+/-4% by beta-adrenergic blockade with propranolol. Methylscopolamine also unmasked small tachycardic responses (5-25 bpm) in 5/7 animals. This tachycardia was prevented by propranolol. Thus both parasympathetic vagal cardiac nerves and sympathetic cardiac nerves are activated during the nasopharyngeal reflex, with increased vagal effects in the sino-atrial node, and increased sympathetic effects in the ventricular myocardium.

Protective mucosal immunity in aging is associated with functional CD4+ T cells in nasopharyngeal-associated lymphoreticular tissue

Our previous studies showed that mucosal immunity was impaired in 1-year-old mice that had been orally immunized with OVA and native cholera toxin (nCT) as mucosal adjuvant. In this study, we queried whether similar immune dysregulation was also present in mucosal compartments of mice immunized by the nasal route. Both 1-year-old and young adult mice were immunized weekly with three nasal doses of OVA and nCT or with a nontoxic chimeric enterotoxin (mutant cholera toxin-A E112K/B subunit of native labile toxin) from Brevibacillus choshinensis. Elevated levels of OVA-specific IgG Abs in plasma and secretory IgA Abs in mucosal secretions (nasal washes, saliva, and fecal extracts) were noted in both young adult and 1-year-old mice given nCT or chimeric enterotoxin as mucosal adjuvants. Significant levels of OVA-specific CD4(+) T cell proliferative and OVA-induced Th1- and Th2-type cytokine responses were noted in cervical lymph nodes and spleen of 1-year-old mice. In this regard, CD4(+), CD45RB(+) T cells were detected in greater numbers in the nasopharyngeal-associated lymphoreticular tissues of 1-year-old mice than of young adult mice, but the same did not hold true for Peyer's patches or spleen. One-year-old mice given nasal tetanus toxoid plus the chimeric toxin as adjuvant were protected from lethal challenge with tetanus toxin. This result reinforced our findings that age-associated immune alterations occur first in gut-associated lymphoreticular tissues, and thus nasal delivery of vaccines for nasopharyngeal-associated lymphoreticular tissue-based mucosal immunity offers an attractive possibility to protect the elderly.

A New Method of Inhalation Anesthesia with Nasopharyngeal Insufflation in Rat Experiment

We have established a new method of anesthesia with nasopharyngeal insufflation for intraoral procedure in rodents. Twelve male Wistar rats weighing 330-390 g were used in this study. Insertion of a feeding tube 1.0 mm in diameter coated with 2% xylocaine jelly was inserted into the nasal cavity approximately 25 mm from the naris, and anesthetization with mixed gas of 100% oxygen with 3-4% enflurane at 0.25-0.5 l/min flow rate was achieved. Using this anesthetic method, a chronic experiment comprising 1-h/day experimental procedure was carried out for 14 days. This method enabled, 1) simple and safe operation of the induction, emergence and anesthetic depth, 2) experimental procedures on the dental/oral region, 3) avoidance of the dyspnea and tachypnea, and 4) avoidance of cumulative effects in daily anesthesia.

Electromyographic activity of the hyoepiglotticus muscle and control of epiglottis position in horses

OBJECTIVE

To determine whether the hyoepiglotticus muscle has respiratory-related electromyographic activity and whether electrical stimulation of this muscle changes the position and conformation of the epiglottis, thereby altering dimensions of the aditus laryngis.

ANIMAL

6 Standardbred horses.

PROCEDURE

Horses were anesthetized, and a bipolar fine-wire electrode was placed in the hyoepiglotticus muscle of each horse. Endoscopic images of the nasopharynx and larynx were recorded during electrical stimulation of the hyoepiglotticus muscle in standing, unsedated horses. Dorsoventral length and area of the aditus laryngis were measured on images obtained before and during electrical stimulation. Electromyographic activity of the hyoepiglotticus muscle and nasopharyngeal pressures were measured while horses exercised on a treadmill at 50, 75, 90, and 100% of the speed that produced maximum heart rate.

RESULTS

Electrical stimulation of the hyoepiglotticus muscle changed the shape of the epiglottis, displaced it ventrally, and significantly increased the dorsoventral length and area of the aditus laryngis. The hyoepiglotticus muscle had inspiratory activity that increased significantly with treadmill speed as a result of an increase in phasic and tonic activity. Expiratory activity of the hyoepiglotticus muscle did not change with treadmill speed in 4 of 6 horses.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings reported here suggest that contraction of the hyoepiglotticus muscle increases dimensions of the airway in horses by depressing the epiglottis ventrally during intense breathing efforts. The hyoepiglotticus muscle may be an important muscle for dilating the airway in horses, and contraction of the hyoepiglotticus muscle may induce conformational changes in the epiglottis.

Correlation on cine MR imaging of size of adenoid and palatine tonsils with degree of upper airway motion in asymptomatic sedated children

OBJECTIVE

The objective of this study was to use MR fluoroscopy to evaluate variations in size of the adenoid and palatine tonsils and the relationship between tonsil enlargement and airway motion dynamics in asymptomatic children during sleep.

SUBJECTS AND METHODS

We performed sagittal midline cine MR imaging (fast gradient-echo series: TR/TE, 8.2/3.6 sec; flip angle, 80 degrees; slice thickness, 8 mm; 128 consecutive images; imaging time, 2 min; displayed in cine mode) in children referred for MR imaging of the brain who required sedation. The largest transverse diameter of the adenoids was recorded. A subjective impression was made as to whether the adenoids were enlarged or normal in size. Palatine tonsils were considered enlarged when a soft-tissue mass was identified on the midline cine images, and maximum diameter was recorded. Enlarged and nonenlarged adenoid and palatine tonsil groups were compared using motion parameters (chi-square or Fisher's exact test): mouth position (opened or closed); vertical motion (present, absent); nasopharyngeal, oropharyngeal, and hypopharyngeal motion (static patent, dynamic patent, intermittent collapsed, or static collapsed, and greatest change in size).

RESULTS

We studied 148 subjects who had a mean age of 3.4 years. The adenoid tonsils were considered enlarged in 64 patients (43%), and the palatine tonsils were considered enlarged in 29 patients (20%). The mean size of the enlarged adenoid tonsils was 11.6 mm and of the nonenlarged adenoid tonsils was 6.2 mm. Enlarged adenoids correlated with the open mouth position (p = 0.0242) and increased dynamic motion of the oropharynx (p = 0.0413). A trend was also seen for increased dynamic motion of the nasopharynx (p = 0.0723). Enlarged palatine tonsils correlated with an increased frequency of dynamic motion of the oropharynx (p = 0.0006) and the nasopharynx (p = 0.0033) and a trend for increased frequency of the open mouth position (p = 0.0692).

CONCLUSION

Large adenoid and palatine tonsil size affects breathing dynamics of the upper airway even in asymptomatic children.

A real-time algorithm for the quantification of blood pressure waveforms

A real-time algorithm for quantification of biological oscillatory signals, such as arterial blood pressure (BP) is proposed which does not require user intervention and works on waveforms complicated by rapid changes in the mean level, frequency, or by the presence of arrhythmia. The algorithm is based on the continous independent assessment of the refractory period (RP). In the first stage, a sample of the signal is band-pass filtered. During the next stage: 1) the local maxima in the filtered signal are identified and their pulse amplitudes (PA) measured on the side opposite to the possible notch position and 2) those maxima whose PA exceeds some threshold are selected and an array of RP values is formed as a fraction of the moving estimate of the interval between successive selected peaks. Finally, the original signal is analyzed by means of two moving averages (MAs) with short and long averaging time intervals. The true peaks are determined as the maxima between intersections of MAs if the peak-to-peak or the intersection-to-intersection intervals since the previous peak and the previous intersection exceed the RP. The algorithm proved to be superior against three commercially available heartbeat detectors yielding an error rate of 0.09%.

Inhalation of warm and cold air does not influence brain stem or core temperature in normothermic humans

The present study tested the hypothesis that inhalation rewarming provides a thermal increment to central neural structures adjacent to the nasopharyngeal region. Auditory-evoked brain stem responses of 14 subjects (7 men and 7 women) were monitored for 25 min while they inspired room air (24 degrees C) followed by hot air (41 degrees C) saturated with water vapor and cold dry air (-1 degrees C). The latencies of peaks I, III, and V and the interpeak latencies (IPLs) I-III, III-V, and I-V were compared among the three conditions with a repeated-measures ANOVA. Changes in IPLs are sensitive markers of changes in brain stem temperature. Tympanic temperature (T(ty)) was measured with an infrared tympanic thermometer. There were no significant differences in T(ty), peak latencies I, III, and V, and IPLs I-III, III-V, and I-V. The results indicate that inhalation of hot and cold air does not influence T(ty), nor does it influence the temperature of the brain stem. We conclude that inhalation rewarming is not capable of warming the vital central neural structures adjacent to the naropharynx.

Acute effects of L- and T-type calcium channel antagonists on cardiovascular reflexes in conscious rabbits

1. The effects of the relatively selective T-type voltage- operated calcium channel (VOCC) antagonist mibefradil were compared with verapamil, an L-type VOCC antagonist, on a range of autonomic reflexes in conscious rabbits. 2. Mean arterial pressure (MAP), heart rate (HR), the baroreceptor-HR reflex, postural adaptation reflex (90 degrees head-up tilt), Bezold-Jarisch-like reflex and the vasoconstrictor component of the nasopharyngeal reflex were assessed before and during i.v. infusion of vehicle (saline), mibefradil or verapamil. Doses of mibefradil that gave low (M1; 0.45 +/- 0.02 microg/mL) and high (M2; 0.93 +/- 0.05 microg/mL) plasma concentrations, or verapamil (0.059 +/- 0.004 microg/mL; n = 6 each) were chosen to mimic clinically observed therapeutic levels. 3. At steady state infusion over 30-90 min, MAP was significantly lower in M2 (- 7 mmHg) and verapamil (- 6 mm Hg) treatments, but only verapamil caused a significant tachycardia (+ 31 b.p.m.) compared with vehicle. Mibefradil (M2) and verapamil decreased the HR range of the baroreflex by 27 and 29%, respectively, but neither treatment affected the vagal or sympathetic constrictor components of the Bezold-Jarisch-like and nasopharyngeal reflexes, respectively. 4. In response to 90 degrees tilt, vehicle- and verapamil-treated rabbits responded with small rises in MAP of 4 +/- 2 and 8 +/- 2 mm Hg, respectively, 5 s into the upright posture, while M1 and M2 caused falls in MAP of 6 +/- 4 and 9 +/- 3 mm Hg, respectively, at 5 s. 5. Thus, both L- and T-type VOCC antagonists, at plasma concentrations in the clinical range, lowered MAP in the conscious rabbit, but only mibefradil caused postural hypotension. We conclude that T-type VOCC may play an important role in the venoconstrictor reflex in response to tilt in the rabbit.

Examination of nasopharyngeal and tracheal somatosensory evoked potential recordings in dogs

OBJECTIVE

To investigate the value of nasopharyngeal and tracheal recordings of somatosensory evoked potentials (SSEP) in anesthetized dogs.

ANIMALS

10 healthy mixed-breed dogs (5 males and 5 females).

PROCEDURE

Square-ware electrical stimuli (50 microseconds duration, 4Hz) were delivered through bipolar surface electrodes to the median nerve of the right forelimb with 7 to 12 mA constant current. The SSEP were recorded with soft electrodes placed on the epipharynx and dorsal wall of the trachea, respectively. Traditional scalp and neck recordings of SSEP were also performed, using SC-inserted needle electrodes. The potentials recorded dorsally and ventrally from the neuraxis were compared to assess the application of these signals for intraoperative neurophysiologic monitoring.

RESULTS

Electrical stimulation of the median nerve resulted in multiphasic potentials recorded from all 4 recording sites. Latency and phase shifts were observed between the far-field potentials placed ventrally and dorsally from the neuraxis.

CONCLUSIONS AND CLINICAL RELEVANCE

Potentials recorded with nasopharyngeal and tracheal electrodes are regarded suitable for intraoperative neurophysiologic monitoring in anesthized dogs.

Magnetic resonance imaging of the levator veli palatini muscle during speech

OBJECTIVE

To obtain detailed anatomic information on the levator veli palatini (LVP) muscle from magnetic resonance imaging (MRI). Quantitative measures of the configuration of the LVP muscle at rest and during speech activities were obtained.

DESIGN

Prospective study using MRI of adult subjects with normal velopharyngeal mechanisms to determine anatomic and physiologic parameters of the levator muscle. The levator veli palatini muscle was imaged at rest and during speech activities consisting of nasal and non-nasal sounds mixed with vowels, consonants, or both (e.g., /ansa, asna, amfa, afma/).

PARTICIPANTS

Ten normal healthy adults (five men, five women) between 21 and 53 years of age and free of oropharyngeal abnormalities.

MAIN OUTCOME MEASURES

Two-dimensional spin echo static images and dynamic fast gradient echo images of the levator muscle in both the sagittal and oblique/coronal planes.

RESULTS

On average across female (F) and male (M) subjects: distance between LVP muscle origin points, 52.6 mm (F), 54.6 mm (M); angle of levator muscle origin at rest, 64.5 degrees (F), 60.4 degrees (M); length of the levator muscle at rest, 44.1 mm (F), 46.4 mm (M); width of levator muscle at lateral margin of velum, 5.5 mm (F), 6.6 mm (M). Both the levator muscle angle of origin and length became progressively smaller from rest, nasal consonants, low vowels, high vowels, and fricatives for both female and male subjects. Across all subjects, there was a 19% reduction in length of the LVP muscle from rest position to fricative production.

CONCLUSIONS

MRI is an effective method of imaging and measuring the LVP muscle and related structures in living subjects. Understanding the normal tissue distribution and quantification of the LVP muscle provides important information for development of a functional biomechanical model of the velopharynx and for improved surgical treatment.

Swallowing function and medical diagnoses in infants suspected of Dysphagia

OBJECTIVE

There has been an increase in infant swallowing disorders as a result of improved survival for infants born prematurely or with life-threatening medical disorders. These infants often have multiple health issues and an increased risk of respiratory complications. However, there is little understanding of the biomechanics of infant swallowing disorders. Therefore, the objectives of this study were to determine 1) the percentage of dysphagic infants who experience laryngeal penetration, aspiration, or nasopharyngeal backflow; 2) reasons for laryngeal penetration/aspiration; 3) whether infants with laryngeal penetration/aspiration clear their airway; and 4) the relationship between swallowing disorders and medical diagnoses.

METHODS

Patients included 43 infants who were referred for videofluoroscopic swallowing studies in a university-affiliated pediatric medical center. Medical charts were reviewed. The videofluoroscopic swallowing studies were recorded on videotape, and each swallow was analyzed for laryngeal penetration, aspiration, nasopharyngeal backflow, cough, airway clearance, and reason for penetration/aspiration. Statistics included chi2 for nonparametric data and measures of central tendency for numeric/timing data.

RESULTS

More than half of the infants experienced laryngeal penetration, aspiration, or nasopharyngeal backflow; however, the first occurrence of these events was after multiple swallows. Only 3 infants experienced laryngeal penetration and aspiration on the first swallow and all 3 had an absent pharyngeal response. Premature infants experienced significantly more nasopharyngeal backflow. Material in the pyriform sinuses before pharyngeal swallowing was associated with penetration/aspiration. In episodes of laryngeal penetration, all patients were able to clear their airway during the swallow without a cough. Almost all infants (8 of 9) who aspirated did not cough or clear their airway.

CONCLUSIONS

This study demonstrated that most infants suspected of dysphagia showed overt abnormalities: laryngeal penetration, aspiration, and/or nasopharyngeal backflow on the videofluoroscopic swallowing study. Most of these infants did not demonstrate abnormalities in the first few swallows but displayed deterioration in swallowing function as they continued to feed. Thus, radiographic assessments in infants must examine multiple swallows. The high incidence of silent aspiration demonstrates the necessity of a videofluoroscopic assessment to evaluate swallowing function in these infants.

Computed tomographic study of the effect of a tongue-tie on hyoid apparatus position and nasopharyngeal dimensions in anesthetized horses

OBJECTIVE

To determine the effect of manual tongue protrusion on the dimensions of the hyoid apparatus, nasopharynx, and oropharynx in anesthetized horses. tongue protrusion on the dimensions of the hyoid.

ANIMALS

5 adult horses.

PROCEDURE

Horses were anesthetized and positioned in sternal recumbency for 2 sequential computed tomographic (CT) scans. Images were acquired with the tongue in a natural position inside the mouth. Then, the tongue was pulled rostrally and secured, and a second CT scan was performed. Dorsoventral length of the hyoid apparatus and angles of the basisphenoid, basihyoid, and ceratohyoid were measured on 3-dimensional reconstructed CT images. Cross-sectional diameters and areas of the nasopharynx and oropharynx were determined on reformatted images in the transverse and longitudinal planes, using osseous landmarks for consistency. Results were tested between the 2 groups to determine significant differences.

RESULTS

We were unable to detect a significant difference between any of the lengths or angles of the hyoid apparatus measured with or without rostral protrusion of the tongue. Similarly, nasopharyngeal and oropharyngeal diameters and cross-sectional areas were not significantly different with or without rostral protrusion of the tongue.

CONCLUSIONS AND CLINICAL RELEVANCE

Tying the tongue rostrally out of a horse's mouth did not influence the position of the hyoid apparatus or dimensions of the nasopharynx or oropharynx in anesthetized horses. Currently, no data suggest that application of a tongue-tie is effective for maintaining stability and patency of the nasopharyngeal or orolaryngeal airways in horses during races.

[The relevance of mirror examination in modern otorhinolaryngology]

INTRODUCTION

The aim of this study was to investigate whether the teaching of mirror examination of the larynx and rhinopharynx is still relevant and to estimate whether it is still a reliable examination.

MATERIAL AND METHOD

Twenty-five patients underwent a mirror examination of the larynx and rhinopharynx by a young doctor, a young otorhinolaryngologist, and a senior otorhinolaryngologist.

RESULTS

Not surprisingly the senior otorhinolaryngologist conducted the most adequate examinations. Forty-three percent of the laryngoscopies were adequate, that is all anatomic structures were seen. Forty-one per cent provided a reasonable survey, that is a few anatomic structures were not seen. This shows that 84% of the laryngoscopies could be used to give a reasonable examination of the larynx. Only 27% of the rhinoscopies were completely adequate, and as many as 49% were inadequate.

DISCUSSION

Routine mirror examination of the larynx adequately provides a reliable diagnosis in most patients. But in some, it is not adequate, and here fibrolaryngoscopy is a good alternative and a more reliable examination. Mirror examination of the rhinopharynx is difficult, so if a disease of the rhinopharynx is suspected, the patient must be given a fibroscopy and biopsy under general anaesthesia.

Study and application of a mathematical model for the provisional assessment of areas and nasal resistance, obtained using acoustic rhinometry and active anterior rhinomanometry

Nasal resistance (NR) depends on the geometrical features and tortuosity of the nasal airway and on the air flow. Knowing the longitudinal distribution of cross-sectional areas (CSAs) in the nasal cavity (which can be obtained using acoustic rhinometry) and the laminar nasal resistance (obtainable by processing the rhinomanometric results), it is possible to calculate, utilizing a mathematical model elaborated on the basis of fluid dynamics, the differential nasal resistance (NRdiff) and the cumulative nasal resistance (NRcum), thus localizing the position at which the highest resistance is concentrated and the related longitudinal distribution. Using a mathematical model, we integrated the sigmoid curves DeltaP/Q of rhinomanometry with the cross-sectional areas obtained using acoustic rhinometry, thus obtaining the normal distribution of differential and cumulative nasal resistances. Afterwards, we empirically reduced the cross-sectional areas corresponding to the head, body, tail and the whole inferior turbinate, recalculating the differential and cumulative nasal resistance distribution curves. The results show that reduction of up to 50% of cross-sectional areas does not substantially affect the resistivity role of the nasal valve, while greater reductions move the highest resistivity point to an area at the junction of the body and the head of the inferior turbinate. The study of the differential nasal resistance trend curves as a function of the reduction of cross-sectional areas shows that the resistance variation of the body and the whole inferior turbinate prevail with reductions of up to 40%, while the variation of cross-sectional areas of the body bordering the inferior turbinate head is predominant with higher reductions. The cross-sectional areas of the nasal airway cavity with highest resistivity are mainly located in an anterior position, where the differential nasal resistances are higher, but there are substantial variations produced by reducing the cross-sectional area of the posterior nasal airway. A similar model can produce provisional values for the results obtainable with functional nasal surgery.

Upper airway pressures in snorers and nonsnorers during wakefulness and sleep

OBJECTIVE

To compare upper airway pressures in snorers and nonsnorers during sleep and wakefulness.

DESIGN

Case series of snorers and nonsnoring controls.

SETTING

Sleep clinic of a university hospital.

METHODS

We used open catheters to measure differential nasopharyngeal and hypopharyngeal pressures in 8 nonapneic snorers with excessive daytime tiredness and 10 healthy nonsnoring controls. Measurements were performed during sleep (with the mouth taped to ensure exclusively nasal breathing) and wakefulness. When awake, the subjects were either seated (with the head neutral, flexed, extended, or rotated) or recumbent (dorsal and lateral positions).

MAIN OUTCOME MEASURES

Comparison of pressures within the group as a function of body position and between the groups as a function of snoring.

RESULTS

Differential nasal and pharyngeal pressures were similar in seated snorers and nonsnorers independently of head position. Assumption of recumbency resulted in significantly increased pharyngeal pressures in nonsnorers (26 +/- 18 Pa seated vs. 52 +/- 46 Pa recumbent, p < .05) and snorers (50 +/- 35 Pa seated vs. 93 +/- 38 recumbent, p < .01). The increase was higher in snorers than nonsnorers. During snoring, sleep differential pharyngeal pressures in snorers were markedly increased compared to quiet sleep (567 +/- 450 Pa during snoring epochs vs. 117 +/- 82 Pa during nonsnoring epochs, p < .01).

CONCLUSIONS

Compared to nonsnorers, recumbent nonapneic snorers have elevated differential pharyngeal pressures indicative of increased upper airway resistance and reduced airway patency; this is present during wakefulness and sleep.

Deep hypothermic circulatory arrest: II. Changes in electroencephalogram and evoked potentials during rewarming

BACKGROUND

Electrophysiologic studies during rewarming after deep hypothermic circulatory arrest probe the state of the brain during this critical period and may provide insight into the neurological effects of circulatory arrest and the neurologic outcome.

METHODS

Electroencephalogram (EEG) and evoked potentials were monitored during rewarming in 109 patients undergoing aortic surgery with hypothermic circulatory arrest.

RESULTS

The sequence of neurophysiologic events during rewarming did not mirror the events during cooling. The evoked potentials recovered first followed by EEG burst-suppression and then continuous EEG. The time to recovery of the evoked potentials N20-P22 complex was significantly correlated with the time of circulatory arrest even in patients without postoperative neurologic deficits (r = 0.37, (p = 0.002). The nasopharyngeal temperatures at which continuous EEG activity and the N20-P22 complex returned were strongly correlated (r = 0.44, p = 0.0002; r = 0.41, p = 0.00003) with postoperative neurologic impairment. Specifically, the relative risk for postoperative neurologic impairment increased by a factor of 1.56 (95% CI 1.1 to 2.2) for every degree increase in temperature at which the EEG first became continuous.

CONCLUSIONS

No trend toward shortened recovery times or improved neurologic outcome was noted with lower temperatures at circulatory arrest, indicating that the process of cooling to electrocerebral silence produced a relatively uniform degree of cerebral protection, independent of the actual nasopharyngeal temperature.

[Warming inhaled air in the nose]

BACKGROUND AND OBJECTIVE

The purpose of this study was to determine whether the temperature at the end of inspiration is the same as the temperature a few seconds after breathing stops at the end of inspiration to study if the nasal mucosa are capable of providing heat during a cessation of breathing.

PATIENTS/METHODS

Fifteen healthy volunteers were included in the study. The temperature at the end of inspiration was compared to the temperature obtained 5 s after cessation of breathing at the end of inspiration and at the end of expiration. Intranasal temperature measurements were taken at three locations in the nose with a miniaturized thermocouple.

RESULTS

The temperature increased during cessation of breathing at all locations. The highest temperature differences between the end of inspiration and 5 s later (breathing at rest) could be observed at the nasal valve area. The lowest temperature difference was found in the nasopharynx. At the end of expiration,the temperature decreased only slightly from the nasopharynx to the nasal valve area.

CONCLUSIONS

The anterior part of the nose in particular is capable of heating the inspired air. This is also important for humidification. Heating of inspired air requires special anatomical conditions of the anterior nasal segment.

Deep hypothermic circulatory arrest: I. Effects of cooling on electroencephalogram and evoked potentials

BACKGROUND

Deep hypothermia is an important cerebral protectant and is critical in procedures requiring circulatory arrest. The purpose of this study was to determine the factors that influence the neurophysiologic changes during cooling before circulatory arrest, in particular the occurrence of electrocerebral silence.

METHODS

In 109 patients undergoing hypothermic circulatory arrest with neurophysiologic monitoring, five electrophysiologic events were selected for detailed study.

RESULTS

The mean nasopharyngeal temperature when periodic complexes appeared in the electroencephalogram after cooling was 29.6 degrees C +/- 3 degrees C, electroencephalogram burst-suppression appeared at 24.4 degrees C +/- 4 degrees C, and electrocerebral silence appeared at 17.8 degrees C +/- 4 degrees C. The N20-P22 complex of the somatosensory evoked response disappeared at 21.4 degrees C +/- 4 degrees C, and the somatosensory evoked response N13 wave disappeared at 17.3 degrees C +/- 4 degrees C. The temperatures of these various events were not significantly affected by any patient-specific or surgical variables, although the time to cool to electrocerebral silence was prolonged by high hemoglobin concentrations, low arterial partial pressure of carbon dioxide, and by slow cooling rates. Only 60% of patients demonstrated electrocerebral silence by either a nasopharyngeal temperature of 18 degrees C or a cooling time of 30 minutes.

CONCLUSIONS

With the high degree of interpatient variability in these neurophysiologic measures, the only absolute predictors of electrocerebral silence were nasopharyngeal temperature below 12.5 degrees C and cooling longer than 50 minutes.

Human nasopharyngeal-associated lymphoreticular tissues. Functional analysis of subepithelial and intraepithelial B and T cells from adenoids and tonsils

Subepithelial and intraepithelial lymphocytes of human adenoids and tonsils were characterized and directly compared to determine the potential contribution of these tissues to mucosal and systemic immune responses. The distribution of T and B cell subsets, cytokine patterns, and antibody (Ab) isotype profiles were similar for adenoids and tonsils. Both tissues contained predominantly B cells ( approximately 65%), approximately 5% macrophages, and 30% CD3(+) T cells. The T cells were primarily of the CD4(+) subset ( approximately 80%). Tonsillar intraepithelial lymphocytes were also enriched in B cells. The analysis of dispersed cells revealed a higher frequency of cells secreting IgG than IgA and the predominant Ig subclass profiles were IgG1 > IgG3 and IgA1 > IgA2, respectively. In situ analysis also revealed higher numbers of IgG- than IgA-positive cells. These IgG-positive cells were present in the epithelium and in the subepithelial zones of both tonsils and adenoids. Mitogen-triggered T cells from tonsils and adenoids produced both Th1- and Th2-type cytokines, clearly exhibiting their pluripotentiality for support of cell-mediated and Ab responses. Interestingly, antigen-specific T cells produced interferon-gamma and lower levels of interleukin-5. These results suggest that adenoids and tonsils of the nasopharyngeal-associated lymphoreticular tissues represent a distinct component of the mucosal-associated lymphoreticular tissues with features of both systemic and mucosal compartments.

Cardiovascular and autonomic effects of omega-conotoxins MVIIA and CVID in conscious rabbits and isolated tissue assays

1. The effects of a novel N-type voltage-operated calcium channel antagonist, omega-conotoxin CVID, were compared with omega-conotoxin MVIIA on sympathetic-evoked activation of right atria (RA), small mesenteric arteries (MA) and vasa deferentia (VD) isolated from the rat. Their effects were also compared on blood pressure and cardiovascular reflexes in conscious rabbits. 2. The pIC(50) values for MVIIA and CVID, respectively, for inhibiting sympathetic-evoked responses were equivalent in RA (8.7 and 8.7) and VD (9.0 and 8.7); however, in MA the values were 8.4 and 7.7. The cardiac to vascular (RA/MA) potency ratios, antilog (plog RA - plog MA), for MVIIA and CVID were 2 and 10. The offset rates for CVID and MVIIA were rapid, and peptide reapplication caused rapid onset of blockade, suggesting limited desensitization. 3. In the conscious rabbit, CVID and MVIIA (100 microg kg(-1) i.v.) caused a similar fall in blood pressure and a tachycardia that rapidly reached maximum. Both peptides decreased the vagal- and sympathetic-mediated components of the baroreflex, but had no effect on the vagal nasopharyngeal reflex. The orthostatic reflex to 90 degrees tilt was blocked by MVIIA with sustained postural hypotension for > or = 90 min after administration. In contrast, CVID caused postural hypotension at 30 min which recovered rapidly. 4. Neither CVID nor MVIIA (3 microg kg(-1) i.t.) significantly altered cardiovascular variables or autonomic reflexes. 5. In conclusion, CVID appears to be relatively weak at inhibiting the reflex response to tilt consistent with its weaker inhibition of rat mesenteric artery constriction to perivascular nerve stimulation. This may point to subtype N-type calcium channel selectivity.

High frequency of chromosome 3p deletion in histologically normal nasopharyngeal epithelia from southern Chinese

We have examined the presence of loss of heterozygosity (LOH) on chromosome 3p in histologically normal nasopharyngeal epithelia (NP), dysplastic lesions, and carcinoma of the nasopharynx from different ethnic and geographic regions. Microdissected normal NP from noncancerous individuals and nasopharyngeal carcinoma (NPC) samples from both the high-risk group (southern Chinese in Hong Kong) and two low-risk groups for NPC (central/northern Chinese in Anhui/Beijing and Caucasians in Toronto) were included. All NPC samples showed high incidence of 3p deletion (81-100%). High frequencies of LOH on 3p were also detected in normal NP (73.9%) and dysplastic lesions (75%) from the southern Chinese. Significant lower frequency of LOH on 3p was noted in normal NP from the low-risk groups (20%) than those from high-risk groups (P = 0.0003). The presence of such genetic alterations in the histologically normal NP and dysplastic lesions suggests that it is an early event in tumor development. The higher frequency of 3p LOH found in normal NP from southern Chinese compared with those from low-risk groups may be related to the distinct cancer incidence among these populations.

[Nuclear magnetic resonance tomography imaging and functional diagnosis of the eustachian auditory tube]

PURPOSE

To develop and evaluate a protocol for the anatomic depiction and functional testing of the auditory tube with the use of MR imaging.

METHODS

Eleven volunteers were included into this study. For the morphological assessment, the imaging protocol included axial and coronal T2-weighted turbo-spin echo sequences (TR/TE = 3194/100 ms) and a T1-weighted gradient echo sequence (TR/TE = 42/4.6 ms). For the functional test a dynamic turbo-gradient echo sequence (TFE) with spectral fat suppression (TR/TE = 15/6.2 ms; 4 sec) was obtained using the single slice technique before and during the Valsalva manoeuvre.

RESULTS

With multi-slice sequences, the osseous part of the auditory tube, the tubal cartilage (middle and lateral lamina), the ciliated epithelium, Ostmann's adipose body and the levator and tensor veli palatini muscles were delineated in all cases. During the Valsalva test, opening of the auditory tube was demonstrated in 20 of the 22 investigated sides using the dynamic TFE single slice sequence.

CONCLUSIONS

The introduced MRI protocol allow visualization of the opening of the auditory tube and provides detailed anatomical information of the nasopharynx. Comprehensive morphological and functional evaluation of the auditory tube becomes possible within a single examination'.

The safety and usefulness of cool head-warm body perfusion in aortic surgery

OBJECTIVE

To determine the safety and usefulness of antegrade hypothermic cerebral perfusion in conjunction with mild hypothermic (tepid) visceral perfusion (so-called cool head-warm body perfusion; CHWB) in aortic surgery; the clinical outcomes and perioperative data on this new technique were retrospectively analyzed.

METHODS

From January 1990 to March 1999, 59 patients underwent ascending aorta or aortic arch surgery using antegrade selective cerebral perfusion (SCP). Three perfusion techniques, differentiated by perfusion temperature, were used, those being deep hypothermia (DH; nasopharyngeal temperature of 20 degrees C, n=14), moderate hypothermia (MH; nasopharyngeal temperature of 28 degrees C, n=17) and CHWB (nasopharyngeal temperature of 25 degrees C and bladder temperature of 32 degrees C, n=28). Selection of the technique largely followed a chronological pattern, in this order: DH, MH and, more recently, CHWB. The three groups were retrospectively compared in terms of operative outcome, duration of cardiopulmonary bypass (CPB) and operation, and intraoperative blood loss.

RESULTS

The early (within 30 days after surgery) mortality/hospital mortality (including operative mortality) was 7.1/21.4, 5.9/11.8 and 3.6/7.1% in the DH, MH and CHWB groups, respectively. The rate of stroke was 7.1, 6.3 and 3.6% in the DH, MH and CHWB groups, respectively. No statistical difference was found in early or hospital mortality, or in the rate of stroke among the three groups. The CPB time, especially the time for rewarming, was significantly shorter in the CHWB than in the DH group. Likewise, the operation time, especially the time after CPB, was significantly shorter in the CHWB than in the DH and MH groups. Blood loss was significantly less in the CHWB than in the DH group.

CONCLUSION

Our data suggest that CHWB perfusion in aortic surgery is a safe and useful technique in shortening the operation time and reducing blood loss, but further prospective study is necessary.

Preliminary study of in vivo autofluorescence of nasopharyngeal carcinoma and normal tissue

BACKGROUND AND OBJECTIVE

In nasopharyngeal cancer, conventional white light endoscopy does not provide adequate information to detect the flat/small lesion and identify the margin of observable tumor. In the present study, we evaluate the potential of light-induced fluorescence spectroscopic imaging for the localization of cancerous nasopharyngeal tissue.

STUDY DESIGN/MATERIALS AND METHODS

We built a multiple channel spectrometer specifically for the investigation of fluorescence collected by a conventional endoscopic system. Nasopharyngeal fluorescence were measured in vivo from 27 subjects during the routine endoscopy. The biopsy specimens for histologic analysis were taken from the tissue sites where the fluorescence were measured.

RESULTS

Two algorithms to discriminate the nasopharyngeal carcinoma from normal tissue were created based on the good correlation between the tissue autofluorescence and histologic diagnosis. For the two-wavelength algorithm, carcinoma can be differentiated from normal tissue with a sensitivity and specificity of 93% and 92%, respectively. For the three-wavelength algorithm with compensation of variation of blood content in tissue, a sensitivity of 98% and specificity of 95% were achieved.

CONCLUSION

Fluorescence endoscopic imaging used with the algorithms developed in this report is an efficient method for detecting the nasopharyngeal carcinoma.