The Influence of an Arterial and Venous Air Embolism on the Hearing Level in Laboratory Mini Pigs

We examined the influence of an experimental venous and arterial air embolism on the hearing level in laboratory mini pigs. Before and after the injection of air a threshold ABR was measured in anaesthetized mini pigs (n=15). A venous air embolism was performed in 6 animals: no changes in the hearing level or in the interpeak latencies Jewett wave V-I were observed in any of the animals before, during or after the application of air. In 9 animals the arterial embolism was done, 2 animals died and had to be excluded. In 6 animals out of 7 a hearing loss was observed starting after the injection of 40 ml air and finally ending in deafness for these 6 animals. The detected hearing loss is probably of cochlear origin, as no prolongations of the interpeak latencies of Jewett wave V-I at 90 dB HL were observed prior to the deafness. Our results show that air bubbles in the arterial circulation lead to cochlear damage ending in deafness. Our research indicates that decompression sickness, which is comparable to the arterial air embolism, is more often the cause of a sensorineural hearing loss after diving than previously believed.     

Effects of trichloroethylene on the human vestibulo-oculomotor system

Ten healthy volunteers were subjected to a vestibulo-oculomotor test battery before, during and 1 hour after trichloroethylene exposure. The concentration of trichloroethylene in inspiratory air was 32-78 ppm (176-429 mg/m3). The concentration of trichloroethylene in venous blood was followed throughout the experiment. The mean pulmonary uptake was estimated. Each test person was also subjected to a control experiment, breathing air free of trichloroethylene. A decreased ability to visually suppress the vestibulo-oculomotor reflex during sinusoidal stimulation was noticed during trichloroethylene exposure. One hour after exposure the test subjects showed a decreased maximum velocity of the voluntary saccade and a decreased ability to follow a sinusoidally moving target.     

The nasal cycle in respiratory defence

The review describes the phenomenon of the nasal cycle, which consists of periodic congestion and decongestion of the nasal venous sinuses and an alternation of airflow from one side of the nose to the other over a period of several hours. The hypothesis is put forward that the nasal cycle may have a role in respiratory defence by; (a) alternation of the work of air conditioning between the nasal passages (b) generation of a plasma exudate which physically cleanses the epithelium and provides a source of antibodies and inflammatory mediators (c) maintaining the patency of the airway during the inflammatory response to infection.     

CSF anatomy with emphasis on relations to nasal cavity and labyrinthine fluids.

Cerebrospinal fluid, occupying the subarachnoid space, is elaborated in an active process by the choroid plexus. It supports the brain and spinal cord and acts in lieu of a lymphatic system for central nervous tissue. Whether or not absorption of CSF into dural venous sinuses is an active or passive process is still controversial. A very thin layer of bone separates the posterior ethmoid air sinus from the subarachnoid space. There appears to be potential in man for flow of cerebrospinal fluid into the perilymphatic space of the inner ear, but it seldom occurs.     

Natural history of sigmoid sinus thrombosis

To demonstrate the evolution of sigmoid sinus thrombosis, we performed a prospective observational study on a 6-year-old girl who presented with mastoiditis, epidural abscess, and occipital osteomyelitis from multiple drug-resistant Streptococcus pneumoniae. She underwent mastoidectomy and partial occipital craniectomy. This procedure produced a window in the occipital bone that allowed serial ultrasonography of the sigmoid sinus during medical treatment. Computed tomography was performed, followed by weekly Doppler ultrasonography used to monitor resolution of sigmoid sinus thrombosis. The natural history of a treated episode of sigmoid sinus thrombosis was illustrated. Venous occlusion resolved over a 4- to 6-week period without surgical drainage or venous anticoagulants. Collateral flow, reversal of normal venous flow, and ultimate return to normal venous transport characterized the period of resolution. We conclude that an occluded sigmoid sinus from mastoiditis can naturally recanalize. Aberrant venous flow can be demonstrated during the period of resolution. This case supports a conservative approach to management of the occluded sinus and suggests that 4 to 6 weeks of antibiotic therapy after removal of perisinus infection is sufficient for cure.     

Venous valves in the neck: implications for microvascular free flap reconstruction.

Successful microvascular free flap reconstruction requires adequate arterial inflow and venous outflow. We report 4 cases that demonstrate the not uncommon occurrence of locating valves in veins during microvascular head and neck reconstructive procedures. Failure to recognize these valves could have compromised the venous anastomosis. The anatomical literature states that veins in the head and neck lack valves, allowing bidirectional blood flow. As a result, there is potential significant flexibility in the selection of recipient veins for the microvascular anastomosis during free flap reconstruction. The unrecognized presence of a venous valve, however, could cause thrombosis of the venous anastomosis and, ultimately, flap failure. This report of venous valves should speak caution to the head and neck microvascular surgeon when he or she is selecting recipient veins in the neck.     

The role of intralesional Pingyangmycin in the treatment of venous malformation of facial and maxillary region

OBJECTIVE: To investigate the effect of intralesional Pingyangmycin injection in venous malformation of facial and maxillary region. MATERIALS AND METHODS: From September 2001 to October 2004, 82 patients were referred with venous malformation for intralesional Pingyangmycin injection. RESULTS: After a minimum follow-up of 2 years, 67 patients (81.7%) developed 76-100% regression in their lesions; 12 patients (14.6%) had 51-75% regression in their lesion; 3 patients underwent surgical excision for the residual swellings. No changes in renal function or cytopenias were encountered. No patients developed chest X-ray changes during the course of therapy. There were no mortalities. CONCLUSION: Intralesional injection of Pingyangmycin is an effective, inexpensive, and safe method in venous malformation of facial and maxillary region. We now favor Pingyangmycin sclerotherapy before considering surgical excision in all cases of venous malformation in our hospital.     

Arterial and venous parathyroid hormone levels in minimally invasive surgery

OBJECTIVE: To establish if venous and arterial parathyroid hormone (PTH) levels are similar during minimal access parathyroid surgery. DESIGN: Prospective study. SETTING: Marshfield Clinic, a large multispecialty tertiary care referral center in central Wisconsin. PATIENTS: All patients who underwent minimally invasive parathyroid surgery over a 10-month period. RESULTS: Fifteen consecutive patients were evaluated. There were 11 women and 4 men, with an average age of 65 years. All patients underwent a preoperative technetium Tc 99m sestamibi scan, with 11 localizing to the site of a probable adenoma. Mean ionized calcium levels were 5.95 mg/dL (1.49 mmol/L) preoperatively and 4.84 mg/dL (1.21 mmol/L) postoperatively. Of 13 patients undergoing both arterial and venous sampling, mean baseline venous PTH level was 221 pg/mL and 37 pg/mL at 10 minutes after excision of suspected adenoma (83% decline). Mean baseline arterial PTH level was 247 pg/mL and 38 pg/mL at 10 minutes after excision (84% decline). Using the Wilcoxon signed rank test, there was no significant difference in the arterial vs venous levels at baseline (P = .70) or 10 minutes (P = .48). CONCLUSIONS: Intraoperative PTH levels during minimal access parathyroid surgery are similar for venous and arterial samples. Blood samples for PTH level monitoring can be obtained using a temporary indwelling arterial line.     

Immediate restoration of basal sensorineural hearing (Mb Meniere) using a pressure chamber.

A new technique for the restoration of basal sensorineural hearing loss in Mb Meniere was described. Three cases with unilateral basal sensorineural hearing loss, fullness of the ear, and tinnitus were reported. In the acute stage of their disease the patients were treated in a pressure chamber where it was possible to increase or decrease the air pressure within the range +/- 110 cm H2O. The equilibration of middle ear pressures to surrounding air pressures was checked. Exposure to underpressure resulted in a rise of the hearing thresholds at low frequencies and relief of subjective symptoms. When the air pressure was increased the hearing thresholds were lowered and the sensation of tinnitus and fullness of the ear was accentuated. Changes in air pressure did not affect the healthy ears or the high frequencies in the diseased ear. Hearing improvement attained at exposure to underpressure seemed to remain at atmospheric pressure level. The investigation was performed on the hypothesis that a distended membranous labyrinth might cause a venous congestion of the vestibular aqueduct, resulting in impaired endolymph absorption in the endolymphatic sac. Possible effects of changes in environmental air pressure on the inner ear were discussed.     

Pulsatile tinnitus cured by mastoidectomy

Tinnitus of venous origin is a rare occurrence. It represents roughly half of cases of vascular tinnitus. The choice of treatment is not easy, even when the diagnosis is certain. Reassurance of the patient is often sufficient. Nevertheless, a surgical treatment is sometimes performed--usually ligature of the internal jugular vein. We present the case of a patient with a right venous pulsatile tinnitus and a history of 5 years of ineffective medical and surgical treatments. Ligature of the internal jugular vein was not chosen in this case: a computed tomographic scan showed filled mastoid cells, and mastoidectomy was performed instead. The tinnitus disappeared immediately after surgery and has not recurred during a 2-year follow-up. The bilateral preoperative sensorineural and conductive hearing loss also disappeared. Pulsatile tinnitus of venous origin is usually treated with ligature of the internal jugular vein. Mastoidectomy is an interesting alternative in selected cases.     

Laryngeal aerodynamics associated with selected voice disorders

Measures of estimated subglottal air pressure and laryngeal air flow during speech production are compared for adults with normal laryngeal function and those with laryngeal abnormalities. The most traditional measure, air flow during sustained vowel production, is not a strong predictor of laryngeal function during speech production. Subglottal air pressure and laryngeal air flow offer insight into voice disorders and provide directions for therapy as well as a method for the quantitative assessment of treatment outcomes.     

Numerical simulation of air temperature and airflow patterns in the human nose during expiration

Recovery of heat and water during expiration is an important but not yet fully understood function of the nose. The presented study investigated cooling of the expiratory air for heat recovery within the human nose applying numerical simulation. A numerical simulation in a bilateral three-dimensional model of the human nose based on computed tomography was employed. Temperature distribution and airflow patterns during expiration were displayed. Cooling of the expiratory air primarily takes place in the areas of inferior and middle turbinate. Areas of the highest decrease in temperature are characterized by turbulent airflow with vortices of low velocity. Numerical results showed good concordance with experimental in vivo temperature measurements. Heating of inspired air not only depends on inspiration but also on expiration. Cooling the warm expiratory air may be regarded as an important factor for heat recovery. Furthermore, the results demonstrate the close relation between heat exchange and airflow patterns.     

Efficiency and limitations of the upper airway mucosa as an air conditioner evaluated from the mechanisms of bronchoconstriction in asthmatic subjects

To elucidate a limit to the efficiency of the upper airway mucosa as an air conditioner, the temperatures of the inspiratory air and mucosa were measured in the cervical trachea. Both of them were affected only minimally by change of atmospheric air temperature during resting nose breathing, but were affected greatly by change of mode of breathing. During hyperventilation through the mouth, when the atmospheric air temperature was 1 degree C, a temperature difference of 9 degrees C was noted between inspiratory air in the cervical trachea and body temperature, together with a mucosal temperature fall by 1.86 +/- 0.61 degree C. Wearing of a mask caused a rise of 3 degrees C in the inspiratory air temperature in the cervical trachea.     

Immunohistopathology of allergic rhinitis and conditions allied

Knowledge of nasal physiology and function is necessary for a proper comprehension of nasal symptoms; a short introduction on this topic follows. It is an important task for the nose to filter, humidify and warm the inhaled air. The shape of the nasal cavity and the structure of the nasal lining seem particularly well suited for this purpose. The narrow inlet to the airway (the internal ostium), the bend of the airflow in the nasopharynx and the slit-like cavity provide for effective sedimentation of practically all particles, larger than 10μm, and also of some smaller particles (2–3 μm).¹ Foreign particles deposited in the nasal filter, contact the local immune system. The airway mucosa is equipped with a secretory IgA immune system, which may help to render deposited micro-organisms harmless,² but also IgE producing cells are found in the mucous membrane and in the regional lymph nodes.³ Therefore, the constant sedimentation in the nose of potent allergenic substances (pollen, animal dander, house dust mite) and the consequent risk of allergic rhinitis is a price which has to be paid for nasal filtration and protection of the lower airways against unconditioned ambient air. The nose is also designed for heating and humidification of the inhaled air. Again the slitlike shape of the cavity is of decisive importance, as the intimate contact between the mucosal surface and the inhaled air is necessary for rapid supply of water and heat to the air the nasal cavity. Normally the air passes the nose at a speed of 2 m/sec.⁴ The numerous seromucous glands,⁵ some anterior serous glands⁶ and subepithelial capillaries of the fenestrated type⁷ form the basis for the supply of 500 ml water a day to the inspired air.⁸ The venous sinusoids seem especially designed for maintenance of a slit-like nasal cavity, so important for normal function. More than half of the nasal blood flow is shunted through an abundance of arterio-venous anastomoses.⁹ A comparison with hot water running in a radiator illustrates the importance of this arrangement for heating of the inspired air.     

Measurement of air flow in the maxillary sinus by hot-film technique.

A method of hot-film-anemometry was developed to investigate the velocity of air flow in the maxillary sinus which has hitherto not been detected by other methods. The hot-film-probe can registrate the slow but rapidly changing air flow dependent on the respiratory cycles. This study was performed during sinuscopy. The average of measurement values by quiet respiration was found in the sinus of 8 cm/sec during a velocity in the nose of 5 m/sec. The respiratory fluctuations in the nose induce a movement stream of circulation in the sinus. When inspiration changes to expiration there was still a flow but at a lower degree. No flow in the sinus could be observed between respiratory cycles. After sniffing the velocity peak rises to higher values. The air flow in the sinus depends on the patency of the ostium. In case of a reduced air flow we can distinguish between a partially open ostia and an obstructed one. The measurement demonstrates an injector-effect beside the influence of pressure difference and diffusion on the ventilation of the sinus.     

Angioarchitecture of keloids. A scanning electron microscopy study of a corrosion specimen]

Three keloids harvested during surgery were prepared for histology and scanning electron microscopy (SEM) of vascular corrosion casts. One well-filled keloid (12 cm x 7 cm) was examined by SEM. This specimen revealed a conspicuous increase in subepidermal venous vessels as well as prominent luminal bulging of the endothelial lining in arterial and venous vessels, shown by prominent surface imprint patterns on cast vessels. There were no tapered or compressed vessels. Blind ending vessels identified by cast morphology as vascular sprouts indicated keloid angiogenesis. The increase in (venous) vessels correlated very closely with the hyperaemic state of the keloid.     

Respiratory and laryngeal responses to an oral air pressure bleed during speech.

Researchers have hypothesized that the respiratory and laryngeal speech subsystems would respond to an air pressure bleed, but these responses have not been empirically studied. The present study examined the nature of the responses of the respiratory and laryngeal subsystems to an air pressure bleed in order to provide information relevant to the nature of motor control for speech. Participants produced a syllable train consisting of 7 syllables of [pa] 10 times with and without an air pressure bleed in place. Acoustic, aerodynamic, and respiratory kinematic data were collected. In the bleed condition, peak intraoral air pressure and average oral airflow during the [a] were lower, lung and rib cage volume excursions were longer, and rib cage volume terminations were more negative. This study provides empirical data demonstrating a clear interaction among the speech subsystems. Both active and passive mechanisms are suggested by the subsystems' responses.     

The Physical Volume Test in impedance audiometry

Impedance audiometry offers a clinically practical method for measuring the physical volume in cc of air space medial to the hermetically sealed probe tip. Knowledge of the air space volume is meaningful when average norms are known, either when the TM is intact or, more significantly, when the TM is perforated. With the latter, the temporally dynamic space changes during external, middle ear and/or mastoid disease, the size of the total air space measured offers objective information when determined over time. The resultant volume can offer an indirect mirror readout of progression or regression of a disease process. Likewise, historically there may be a close relationship between eustachian tube function and the overall air cell space within the petrotympanomastoid bone. In such conditions, the smaller the air cell space, the poorer the eustachian tube function. The PVT offers a more expedient clinical tool over roentgenography for measuring the viable air space of the middle ear and petromastoid air cell system. Since the PVT is used primarily with an open system (i.e. with a perforated TM) electroacoustic volumetric determinations with a 220 Hz acoustic input more reliably represents the actual volume present.     

The neglected emissary vein in mastoidectomy; persistent petrosquamosal sinus in the laterally located sigmoid sinus

The emissary veins are residual connections between intracranial venous sinuses and their extracranial drainage, which if not diagnosed preoperatively could be a cause of severe hemorrhage at the time of surgery which may be life threatening. The petrosquamosal emissary sinus (PSS) which is a rare embryonic emissary vein along the petrosquamosal fissure of the temporal bone connects dural sinuses with external jugular venous system. The PSS has been known to regress during fetal and early postnatal life. The imaging diagnosis of the PSS has been rarely reported in humans. We report the presence of the PSS with laterally located sigmoid sinus in patient with chronic otitis media. Our hope is that this report will be useful to the otologist during surgery.     

In vitro measurements of aerodynamic characteristics of an improved tracheostoma valve for laryngectomees

Tracheostoma valves are often required in the rehabilitation process of speech after total laryngectomy. Patients are thus able to speak without using their hands to close the tracheostoma. The improved Groningen tracheostoma valve consists of a “cough” valve with an integrated (“speech”) valve, which closes for phonation. The cough valve opens as the result of pressure produced by the lungs during a cough. The speech valve closes by the airflow produced by the lungs, thus directing air from the lungs into the esophagus at a deliberately chosen moment. An experimental setup with a computer-based acquisition program was developed to measure the pressure at which the cough valve opened and the flow at which the speech valve closed. In addition, the airflow resistance coefficient of the tracheostoma valve was defined and measured with an open speech valve. Both dry air from a cylinder and humid expired air were used. Results showed a pressure range of 1–7 kPa to open the cough valve and a flow range of 1.2–2.7 l/s to close the speech valve. These values were readily attained during speech, while the flow range occurred above values reached in quiet breathing. The device appeared to function well in physiological ranges and was optimally adjustable to an individual setting. No significant differences were measured between air from a cylinder and humid expired air. Findings showed that methods used to obtain results could be employed as a reference method for comparing aerodynamic characteristics of tracheostoma valves. Received: 13 February 1997 / Accepted: 16 September 1997