Electrocochleographic recordings in acute and healed perilymphatic fistula

In this study, the summating potential (SP) and action potential (AP) amplitude ratio was measured in 15 guinea pigs before and after surgical induction of a round window fistula. The round window fistula was then allowed to heal, and recordings were obtained after 1 month. Stimuli included 8000-Hz and 2000-Hz tone bursts and click stimuli at levels ranging from 100-dB peak equivalent sound pressure level to AP threshold. Immediately after fistula induction, a statistically significant enlargement in the SP/AP amplitude ratio occurred in response to the click and the 8000-Hz tone-burst stimuli. No change in the SP/AP amplitude ratio was observed for the 2000-Hz stimuli. After healing, the SP/AP amplitude ratio generally returned to prelesion values. No unhealed perilymphatic fistulas were observed in any of the 15 guinea pigs at 1 month after fistula induction. Considering the difficulty of diagnosing perilymphatic fistula in humans, it is encouraging to note that, at least in animals, noninvasive electrophysiologic recordings may perhaps be sensitive to the presence of patent perilymphatic fistula.

Chronic perilymph fistula in the guinea pig with implications in the human

To improve understanding of the pathophysiology of perilymph fistulas, a predictable animal model of a chronic fistula was developed. Our findings suggest that guinea pig fistulas do not remain patent for prolonged periods. By extrapolating these findings to humans, we postulate that the symptoms and signs of perilymph fistula are possibly due not to one prolonged constant fistula, but rather a series of "blowouts" from an inherent congenital or posttraumatic weak spot in either the round or oval window. We feel that a diagnosis of perilymph fistula must be considered in any patient presenting with a Meniere's-like symptom set concomitant with a congenital inner ear deformity or a history of inner ear trauma.

Penetrating wounds of the ear with oval window fistulas. Reports of 2 cases

In 2 patients with penetrating wounds of the ear lesions involved the tympanic membrane and the ossicular chain. The long process of the incus was lying on the fallopian canal and the stapes was deeply depressed into the vestibule. In spite of a large oval window fistula, cochleovestibular signs were minimal. The fistula was sealed with adipose tissue and the stapes replaced by a Teflon-platinum piston prosthesis. The incus was repositioned and supported by a fat graft placed between the fallopian canal and the long process. This original technique of reconstructing the ossicular chain gave satisfactory functional results in both patients.

"Floating" labyrinth. Pathophysiology and treatment of perilymph fistula

Collapse of the membranous labyrinth of the pars superior is a morphological change observed in 50% of animals with experimentally produced perilymph fistula, although the extent and degree of the collapse may vary greatly. The moderately collapsed membranous labyrinth may drift with CSF and/or perilymph pressure changes and this may stimulate sensory cells of the utricle and/or semicircular canals if the sensory cells are intact and the collapsed wall is in contact with the otolithic membrane and/or cupula. This condition is termed "floating" labyrinth. Caloric irregularity is often observed in electronystagmograms recorded from animals with experimental perilymph fistula. This is also observed in patients with perilymph fistula. Partial destruction of the vestibular organs using argon laser was performed in a patient with perilymph fistula who was incapacitated because of persistent positional vertigo after closure of the oval window fistula. Irradiation of the argon laser beam was directed to the macula utriculi, utriculoampullary nerve and singular nerve. The hearing of the patient was maintained, and vertigo disappeared after laser labyrinthectomy.

Inner ear morphology of experimental perilymphatic fistula

The inner ear pathology of experimental perilymphatic fistula (EPLF) is described. EPLF was produced by injecting artificial perilymph into the subarachnoid space, or by suctioning 4 microL of perilymph through one of the round window membranes of the guinea pig. The animals were either killed immediately, or were kept alive for 3 weeks to 3 months. The conventional celloidin embedding method was employed for morphologic study. Vestibular function of the animals was tested by observing spontaneous nystagmus and positional nystagmus after the experiment. The caloric test was also performed. Various pathologic changes of the membranous labyrinth were observed. In the cochlea these included rupture or collapse of Reissner's membrane, bulging of Reissner's membrane, loss of hair cells, and compression of the organ of Corti. Pathology of the otolithic organs and semicircular canals mainly consisted of collapse of the membranous labyrinth. Clinical symptoms in patients with perilymphatic fistula (PLF) are explained, based on our experimental findings. Electronystagmography (ENG) of EPLF animals showed either no caloric response or, with a longer duration, caloric irregularity. Prolonged unsteadiness in patients may be due to "floating" labyrinth.

On the pathomechanism of cochlear dysfunction in experimental perilymph fistulas

The mechanism leading to hearing impairment in perilymph fistulas was investigated in guinea pigs with perforated round window membranes (RWM) by analyzing alterations of inner ear fluid pressure, changes of auditory function following manipulations to get presumed air bubbles out of the cochlea ("positional audiometry"), and temporal bone sections. The instantaneous loss of normal positive inner ear fluid pressure after RWM perforation had no immediate effect on auditory function. Inner ear pressure was restored 4 days following RWM perforation. "Positional audiometry" was negative in guinea pigs with perforated RWM. All ears in which auditory thresholds had increased had additional iatrogenic lesions at the spiral lamina. Fistulas in the RWM per se do not affect auditory thresholds. The question of the surgical repair of fistulas was not directly addressed; it only can be concluded that there are no direct sequelae of an isolated fistula which induce auditory impairment and which could be prevented by surgical repair of the fistula.

Effects of persistent perilymph fistula on the inner ear

To study the effects of a persistent perilymph fistula on the cochlea, a small cannula was inserted into the scala tympani of the basal turn of cochlea in guinea pigs. A month later, cochlear morphology and blood flow were studied using either histological evaluation or the microsphere surface preparation technique. Some animals showed no cochlear morphologic changes or no cochlear blood-flow reduction, even if tubal patency was maintained and perilymph leakage lasted for 1 month. This suggests that a prolonged perilymph fistula, per se, causes no permanent cochlear damage. However, in some animals, hair cell damage and cochlear blood-flow disorders were observed. These observations and the causes of hearing loss in clinical cases of perilymph fistula were studied.

Clip electrode method for recording eye movements in experimental animals

Both the guinea pig and squirrel monkey were used in this study. An animal model for inner ear disease was established, and each animal was subjected to vestibular function tests consisting of spontaneous nystagmus recording, positional testing, caloric testing, and optokinetic stimulation testing. Recordings of nystagmus in the guinea pig and squirrel monkey were successfully obtained by using newly devised clip electrodes. A variety of nystagmic patterns in animal models following experimentally created perilymphatic fistula and labyrinthectomy are presented in this study.

Pulmonary function tests in bronchopleural fistula

A 53-year-old white man underwent a left pneumonectomy for alveolar cell carcinoma. His postoperative course was complicated by pneumonia. At a follow-up clinic visit, the patient complained of a "roaring sound" during respiration. A follow-up PFT did not show the expected loss of volume (nitrogen washout) from a preoperative PFT, suggesting a bronchopleural fistula. A chest x-ray film and xenon lung scan confirmed the diagnosis. The fistula was surgically repaired.

Perilymphatic fistula: surgical experience in the United States

One survey sent to 6953 individual otolaryngologic practices and 106 departments of otolaryngology at teaching hospitals in the United States, and a more limited survey of 75 patients operated on for perilymphatic fistula (PLF) at the House Ear Institute, addressed aspects of managing PLF: surgical incidence, reliability of diagnostic test, preoperative observations, and disability after surgery. Of surgeons sampled, 93% estimated incidence of PLF surgery to be less than or equal to 1 per 1000 otolaryngologic outpatient visits. The most reliable diagnostic indicators were history, symptomatology, and tympanometric and electronystagmographic fistula tests. About 72% of surgeons reported less than 4 weeks' average delay before surgery. Most surgeons and patients (greater than or equal to 70%) rated length of disability before return to work, exposure to noise, travel by airplane, swimming, and heavy lifting, at several weeks to several months. Diving was the most restricted activity. Results suggest that incidence of surgery and disability with PFL in the United States is very limited.

Management of malignant air leak in a child with a neonatal high-frequency oscillatory ventilator

A 10-year-old, 36-kg child with a malignant air leak who failed conventional mechanical ventilation and high-frequency jet ventilation was successfully treated with a neonatal high-frequency oscillatory ventilator for 31 days. Since the air leak resolved with minimal hemodynamic compromise, this technique may have application in the management of respiratory failure and air leak in the older and larger child for prolonged periods of time.

Interactive inner-ear/middle-ear disease, including perilymphatic fistula

Pathologic interactions between the middle ear and inner ear occur with 1) congenital anomalies, 2) trauma, 3) infection/inflammation, 4) tumors, 5) granulomas, 6) ototoxic eardrops, 7) cochlear implants, 8) otosclerosis, 9) Meniere's disease (decompensated) and Meniere's disease (with perilymphatic fistula), and 10) perilymphatic hypertension. Clinical and pathological characteristics are briefly categorized in this survey. Comments are made concerning the clinical utility of exploratory tympanotomy in diagnosis and treatment of pathologic conditions in the middle ear and pathologic conditions that are interactive between middle ear and inner ear.

The tongue flap: placement and fixation for closure of postpalatoplasty fistulae

A tongue flap is frequently used for closure of fistulae following cleft palate repair. Early tongue flap dehiscence is a troublesome complication. While the tongue flap is a very effective means of functionally obliterating the transpalatal oronasal opening, the final appearance of the repair leaves much to be desired. More often than not, the tongue tissue appears bulky and unnatural in the roof of the mouth. A method is described that overcomes the problem of flap detachment during the early postoperative period by suspending and supporting the tongue pedicle with a palatal sling. On peroral view, the repaired area has a better appearance when the tongue flap lines the nasal side rather than the oral side as in conventional procedures.

Early endoscopic fibrin sealing of high-output postoperative enterocutaneous fistulas

In seven patients with high-volume enterocutaneous fistula following gastric surgery, a new method of treatment was used. Fibrin tissue adhesive was applied transintestinally under endoscopic guidance, in one or multiple sessions, to occlude the anastomotic dehiscence and the perianastomotic cavity. Fistula output diminished rapidly in all cases, and complete closure was endoscopically confirmed. There were no complications related to the method. Because of the simplicity and safety of this procedure compared with the complexity of surgical treatment and the persistently high mortality associated with conservative management, interventional endoscopic approach is suggested as an option for treatment of high-volume alimentary fistula.

Effect of perilymphatic air perfusion on cochlear potentials

Perilymphatic fistula is now widely recognized to cause acute profound hearing loss. It is still controversial, however, which mechanism it is that causes the reversible hearing loss. Recently, it has been suggested by two groups of researchers that the intrusion of air bubbles into the perilymphatic space (a condition called pneumolabyrinth or aerolabyrinth) through the ruptured labyrinthine window(s) may be one of the causes. In order to examine the mechanism underlying the hearing loss associated with pneumolabyrinth, the perilymphatic space of the guinea pig cochlea was perfused with air and cochlear potentials were recorded. Although perfusion of the scala tympani with air at a rate as high as 200 microliter/min caused an immediate and drastic decrease of the cochlear microphonics (CM) and the compound action potential (AP), it had little effect on the endocochlear dc potential (EP) during perfusion for 20 min. A decline in EP was seen in half the ears, but only when the duration of perfusion exceeded 30 min. These results show that the EP has an amazing resistance to air trapped in the scala tympani of the cochlea and that the initial decrease of hearing acuity after the elimination of perilymph from the scala tympani (or introduction of air into the scala tympani) is probably due to interference in CM and AP generation mechanisms rather than to strial dysfunction.

The effects of chemotherapy on murine wound healing and orocutaneous fistula closure

The effects of cisplatin and 5-fluorouracil on wound breaking strength and the rate of closure of an orocutaneous fistula were studied in 80 male rodents. Treatment rats received a total of 4.6 mg/kg cisplatin and 62 mg/kg 5-fluorouracil in six doses/12 days; control rats received 0.9 per cent saline. After treatment, 30 treatment and 30 control rats received a dorsal skin incision which was closed primarily. Wound breaking strength were tested at one, three and five weeks in ten rats from each group. An 8-mm orocutaneous fistula was made in the remaining ten treatment and ten control rats; the rate of closure was noted weekly. Cisplatin and 5-fluorouracil did not significantly impair wound breaking strength at one, three, or five weeks. The rate of closure of the orocutaneous fistula was not effected by cisplatin/5-fluorouracil. The chemotherapy caused severe facial cellulitis and death in four orocutaneous fistula rats. Combined chemotherapy with cisplatin and 5-fluorouracil should not interfere with planned surgical care of head and neck tumors. Concomitant antibiotic coverage, however, is advocated.

Vestibular effects of chronic perilymph fistula in the cat

Chronic, unilateral perilymph fistulae were created in cats by removal of the round window membrane and placement of a tympanostomy tube into the round window. Rotary chair, fistula, caloric, and vestibulospinal tests were performed before and after fistulization, and periodically for 2 weeks. At 2 weeks, patency of the fistula was documented by fluorescein injection into the spinal fluid and visualization of leakage into the middle ear bulla via the fistula. All the cats had a patent fistula at 2 weeks, but one of the three cats had a greater perilymph leak than the others. The cat with the more active leak had a spontaneous nystagmus toward the side of the fistula on the first postoperative day; this changed to nystagmus toward the opposite side by the third postoperative day. The other cats had a spontaneous nystagmus toward the opposite side from the first postoperative day. Most abnormal test results returned to normal in the first week after fistulization. Histologic study of the temporal bones revealed that the cat with the greater leak had a wider cochlear aqueduct than the other cats.

Summating potential/action potential ratio in perilymph fistula

A prospective study of electrocochleography in patients with clinically suspected perilymph fistula was undertaken to determine its predictive value in that disorder. One hundred forty-four patients suspected of having perilymph fistula had electrocochleography performed--34 of these (39 ears) had exploratory tympanotomy. Of the 19 ears with normal preoperative summating potential/action potential (SP/AP) ratio, ten had perilymph fistula identified at the time of surgery. Of the 20 ears with abnormal SP/AP ratio, 16 had perilymph fistula confirmed at exploration, 18 had resolution of symptoms after oval window and round membrane grafting, and only one ear had postoperative persistence of the abnormal SP/AP ratio. This study suggests that an abnormal SP/AP ratio is not only predictive of endolymphatic hydrops, but also of perilymph fistula (both problems of inner ear fluid imbalance). This study also suggests that, while abnormal SP/AP ratio is fairly specific for inner ear fluid imbalance, it is not sensitive.

The dynamic posturographic pressure test for the presumptive diagnosis of perilymph fistulas

A diagnosis of perilymph fistulas (PLFs) can be made only by identification of repeated accumulation of crystal-clear fluid from an otic capsule defect or labyrinthine window at tympanotomy. It would be highly desirable to base a decision to operate for the diagnosis and management of PLFs on a database that includes quantitative test data, which confirms, with a high probability, a clinical suspicion of PLF. This article reviews progress in the development of a test of the vestibular response to external auditory canal pressure changes as recorded by dynamic posturography. Based on results to date, it appears that a fistula test with dynamic posturography is more sensitive than those based on VOR responses. This may be due to the ability of dynamic posturography to isolate vestibular from both visual and somatosensory influences on motor responses during external canal pressure changes.

[Effect of a synthetic somatostatin analogue with delayed action (SMS 201-995) on the biliary expenditure in a patient with an external biliary tract fistula]

The effect of treatment with a long acting analogue of somatostatin (SMS 201-995) administered by subcutaneous route 165 micrograms every eight hours in a patient with a external biliary fistula is reported. There was a significant reduction of the daily fistula output during treatment when compared with the basal periods (p = 0.04), with an average decrease of 270 ml/day during the first period of treatment and 357 ml/day when the drug was administered the second time (p = 0.04). There where not changes in the chemical composition of the bile neither adverse side effects were observed during treatment. These results suggest that SMS 201-995 might be useful in the treatment of external biliary fistulas.

ECoG and perilymphatic fistulae: an experimental study in the guinea pig

Perilymph fistulae present a diagnostic dilemma to the clinician. As yet, there is no readily available, widely accepted diagnostic test. Electrocochleography (ECoG), with the advent of extratympanic recording techniques, has become a clinically applicable probe of cochlear function. Clinical ECoG was used to study guinea pigs (n = 35) both before and after surgical fistulization (n = 18) or fistulization and repair (n = 17) of the round window membrane. The animals were killed, and histopathologic examination of the temporal bones was carried out 0, 1, 3, 4, 7, 10, 14, 21, and 28 days after surgery. Of the 33 animals that survived surgery, 30 demonstrated ECoG wave-forms. No significant difference between the preoperative and postoperative wave-forms could be detected. Histopathologic study showed rapid healing of the fistulae, with no evidence of hydrops. Although there appeared to be a relatively selective loss of the outer hair cells of the cochlear basal turn, autolysis precluded detailed analysis. ECoG, as performed clinically, does not appear to detect the presence, spontaneous healing, or repair of a round window membrane fistula in the guinea pig.

Perilymphatic fistula in the guinea pig

Clinical reports on perilymphatic fistulae (PLF) of the round window membrane (RWM) have shown different degrees of hearing loss. However, the hearing can also be entirely unaffected. Experimentally induced PLF of the RWM in animals showed results similar to those of the clinical reports, although some researchers have concluded that perforation of the RWM per se does not necessarily induce significant hearing loss. The purpose of the present study was to clarify if, and how, PLF of RWM in the guinea pig actually affects the auditory action potentials. During 1 h of observation following perforation of the RWM, the immediate and continuous effect of the PLF was evaluated. In more than 50% of the animals, different amounts of threshold shift were obtained. In another group of guinea pigs an attempt was made to clarify the findings by reducing the cerebrospinal fluid pressure before perforating the RWM.

Bronchocutaneous fistula in dogs: influence of fistula size and ventilatory mode on airleak

Bronchocutaneous fistula (BCF) can originate at different levels, from the major airways to the peripheral lung. Little is published on the influence of the fistula origin or the ventilatory effect of the airleak. This study evaluates relative CO2 elimination via fistulas of various size and how different ventilatory modes influence both the quantity and quality, i.e., oxygen and CO2 content, of the airleak. We created BCF with five polyethylene tubings of different diameters (tube 1, 3.0 mm; tube 2, 4.0 mm; tube 3, 5.1 mm; tube 4, 6.4 mm; tube 5, 9.8 mm) in nine dogs. Six modes of ventilation were used with each tubing: spontaneous breathing (SB), pressure support (PS), high frequency (HF), assisted controlled with inspiration set at 20% (AC20) and at 67% (AC67) of the respiratory cycle, and AC20 with an end-expiratory pressure of +10 cm H2O (PEEP). For each ventilatory mode, the fistula air flow (Vf), CO2, and oxygen partial pressure of fistula air (PfCO2 and PfO2) and arterial blood were measured. Vf was measured for all tubes, while gas analysis was done for tubes 1, 3, and 5 only. As expected, Vf increased with tubing size. Vf was higher with AC67 and PEEP than with the other ventilatory modes. PfCO2 was not significantly influenced by the tube size and Vf. Fistula air alveolization was increased only with HF ventilation. Air leaked via the fistula contributed significantly to gas exchange; even when expiration was totally via the fistula, the arterial gases remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of gas flow through a bronchopleural fistula

To assess the determinants of bronchopleural fistula (BPF) flow, we used a surgically created BPF to study 15 anesthetized intubated mechanically ventilated New Zealand White rabbits. Mean airway pressure and intrathoracic pressure were evaluated independently. Mean airway pressure was varied (8, 10, or 12 cmH2O) by independent manipulations of either peak inspiratory pressure, positive end-expiratory pressure, or inspiratory time. Intrathoracic pressure was varied from 0 to -40 cmH2O. BPF flow varied directly with mean airway pressure (P less than 0.001). However, at constant mean airway pressure, BPF flow was not influenced independently by changes in peak inspiratory pressure, positive end-expiratory pressure, or inspiratory time. Resistance of the BPF increased as intrathoracic pressure became more negative. Despite increased resistance, BPF flow also increased. BPF resistance was constant over the range of mean airway (P less than 0.01) pressures investigated. Our data document the influence of mean airway pressure and intrathoracic pressure on BPF flow and suggest that manipulations which reduce transpulmonary pressure will decrease BPF flow.

A case of a right coronary artery to left ventricle fistula observed over twenty years

Since the natural history of a coronary artery to left ventricle fistula is not well known, a case of such a fistula in 36-year-old female patient, followed for 20 years is presented. Two-dimensional echocardiography performed as a follow-up examination revealed enlargement of the right coronary artery and the right Valsalva sinus. Two-dimensional color flow mapping showed the jet flow to the apex from the base of the left ventricle only during the diastolic phase. An aortogram confirmed that enlargement of both the right coronary artery and the right Valsalva sinus had occurred during the 20 years. The shunt flow ratio was about 50%. The Symbas procedure, closing of the coronary artery fistula by arteriotomy directly over the site of the fistula, was performed with the aid of extracorporeal circulation. Our findings indicate that enlargement of the shunted coronary artery and its Valsalva sinus can occur gradually where there is a relatively large shunt flow. Therefore, early surgical treatment is recommended in cases like this one.

Round window reflex and oval window fistulae

The round window reflex is normally absent in stapedial fixation. In this study, six cases of oval window fistula are described in which the round window reflex was absent. This is probably because there is insufficient pressure transmitted to the round window membrane through the perilymph because of leakage from the oval window. This is considered as an important diagnostic sign of oval window/stapes footplate ligament disruption.

Coronary artery fistula in the heart transplant patient. A potential complication of endomyocardial biopsy

All follow-up annual cardiac catheterizations performed on recipients of orthotopic heart transplant were reviewed, and 14 patients with coronary artery fistula were identified. The prevalence (8.0%, 14 of 176 patients) was strikingly higher than that for patients without transplant (0.2%) who underwent routine cardiac catheterization. These 14 patients had 21 coronary artery fistulas: single in nine and multiple in five patients. Fifty-two percent arose from the right, 43% from the left anterior descending, and 5% from the circumflex coronary artery. All drained into the right ventricle. Four patients underwent oximetric evaluation, and left-to-right shunting was not detectable. No patient had symptoms attributable to the fistula. Hemodynamic measurements were similar to those of a control group of 28 age- and sex-matched recipients of heart transplant without coronary artery fistula; however, the cardiac index (p = 0.02) and pulmonary artery oxygen saturation (p = 0.03) were significantly higher, and the arteriovenous oxygen difference (p = 0.01) was significantly lower in the group with coronary artery fistula. The histologic features of rejection, large arterioles, or epicardial fat on any biopsy specimen predating coronary artery fistula diagnosis were not associated with the development of the fistula when the two groups were compared. Nine patients (11 coronary artery fistulas) had follow-up studies performed, and three fistulas were larger, three were unchanged, two were smaller, and three had resolved. No complications of coronary artery fistula developed during a mean follow-up of 28 months (range, 12-42 months).(ABSTRACT TRUNCATED AT 250 WORDS)

Conventional versus high frequency jet ventilation with a bronchopleural fistula

A bronchopleural fistula (BPF) is an aberrant pathway through which inspired gas exits the lungs. A BPF may cause significant respiratory compromise, which in turn may result in the need of mechanical ventilation. The purpose of this study was to compare the efficacy of conventional positive pressure ventilation (CV) with high frequency jet ventilation (HFJV) using increasing increments of positive end expiratory pressure (PEEP) in the management of an induced BPF. A reproducible model of a BPF was surgically created in 10 mongrel dogs. Measurements of blood pressure (BP), cardiac output (CO), mean airway pressure (Maw), peak airway pressure (Paw), and fistula flow (FF) were carried out with the chest closed. Selective occlusion of the BPF allowed for blood gas stabilization at increased values of PEEP. Paired observations were performed at 0, 5, 10, 15, and 20 cm H2O of PEEP, while maintaining PaCO2 between 30 and 50 Torr. There was no difference in BP or CO between ventilation methods even though significantly lower Maw and Paw pressures were obtained using HFJV. While FF increased significantly with each increment of PEEP, there was no improvement in flows obtained using HFJV. This acute model of a BPF demonstrated that increasing PEEP dramatically increases FF irrespective of the method of ventilation.

The rapid induction by interleukin-2 of pulmonary microvascular permeability

The clinical use of interleukin-2 (IL-2) is limited by severe cardiopulmonary dysfunction. This study examines the mechanism of respiratory failure related to IL-2, using sheep with chronic lung lymph fistulae. Awake animals were infused with an intravenous (I.V.) bolus of IL-2 10(5) U/kg (n = 5) or its excipient (EXC) control (n = 3), every 8 hours for 4 to 5 days. Cardiopulmonary function was monitored daily for at least one 8-hour period. Within 2 hours after each IL-2 administration, mean pulmonary arterial pressure (MPAP) rose. On Day 1, the mean rise was from 13 to 26 mmHg (p less than 0.05), and on Day 5, to 29 mmHg (p less than 0.05). MPAP returned to baseline levels after 2-3 hours. Pulmonary arterial wedge pressure was unchanged from 4 mmHg. There were transient falls in arterial oxygen tension, from 88 to 77 mmHg on Day 1 and to 73 mmHg (p less than 0.05) on Day 5. Lung lymph flow (QL) rose from 2.4 to 6.8 ml/30 minutes (p less than 0.05) on Day 1, and from 4.7 to 10.2 ml/30 minutes (p less than 0.05) on Day 5, whereas the lymph/plasma protein ratio increased on Day 1 from 0.69 to 0.83 (p less than 0.05) and from 0.63 to 0.71 (p less than 0.05) on Day 5. This documents an increase in pulmonary microvascular permeability. Thromboxane (Tx)B2 levels increased transiently after each IL-2 injection in plasma from 195 to 340 pg/ml (p less than 0.05) and in lung lymph from 222 to 772 pg/ml (p less than 0.05) on Day 1, and to similar levels on Day 5. There was a progressive rise in cardiac output from 5.7 to 8.6 1/minute (p less than 0.05) during the 5 days of infusion. Systemic blood pressure did not change. Temperature rose from 39.1 to 41.2 C (p less than 0.05), and shaking chills were common. There was a progressive fall in leukocyte count, from 8.4 to 3.2 X 10(3)/mm3 (p less than 0.05) by Day 5, reflecting a 77% fall in lymphocytes. Lung lymph lymphocyte counts rose, and lymphocyte clearance increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary artery to the left atrium fistula as an unusual cause of cyanosis in the newborn

A fistula between the pulmonary artery (PA) and the left atrium (LA) is a rare form of congenital heart disease, 34 cases having been described in the literature, all from the right pulmonary artery (RPA). Only six cases were diagnosed in the newborn period. We report such a case, diagnosed at 1 day of age by Doppler echocardiography, with an unusual site of the fistula.

Somatosensory evoked potentials in a patient with a cervical glioma and syrinx

Short-latency somatosensory evoked potentials (SSEPs) were obtained in a 61-year-old patient with a cervical spinal cord glioma extending from C3 to C7. SSEPs in response to tibial nerve stimulation were normal; however, all components of the median nerve responses were markedly abnormal bilaterally (except for normal brachial plexus responses). This selective abnormality of median nerve SSEPs has not been reported previously in a patient with cervical cord tumor associated with a syrinx and illustrates the use of the SSEP in the anatomical localization of the lesion.

Chronic perilymphatic fistula: experimental model in the guinea pig

Chronic perilymphatic fistulas were created in guinea pig cochleas using silicone rubber tubing placed into the scala tympani through the round window. Fistula patency was determined by fluorescein perfusion into cerebral spinal fluid. Fistula were found to be patent in 6 of 6 animals at 7 days and 8 of 13 animals at 28 days. Analysis of ABRs revealed threshold increases of 10 to 15 dB across all frequencies at 1 hour and 7 days. However, thresholds returned to pre-fistula levels by 28 days. Animals with acute fistulas (simple laceration of the round window) had similar threshold increases at 1 hour; however, recovery to baseline levels occurred by day 7. Control animals with intact round windows did not have threshold shifts. Scanning electron microscopy revealed hair cell loss localized to the apical and basal turns of the cochlea. The morphologic changes observed occurred acutely (within 7 days) and were not progressive, despite the presence of a fistula. Hair cell loss or degeneration did not correlate with hearing loss.

An electrophysiologic study of experimental perilymphatic fistula

This study was undertaken to elucidate the mechanism that causes sensorineural hearing loss in clinical cases with perilymphatic fistula. Perilymph was experimentally aspirated through the round window membrane in 17 guinea pigs. The extent of cochlear damage was examined electrophysiologically as well as histopathologically. Immediately after aspiration, several types of changes in summating potential (SP) were observed. Two animals without a polarity change of the SP showed only slight threshold changes in both cochlear microphonic and action potentials, and no specific histopathologic changes in the cochlea. Reversed polarity of the SP was observed in three animals, of which one showed a high-amplitude negative SP followed by rapidly progressive hearing loss. Bulging of Reissner's membrane was confirmed histopathologically in this case. The SP disappeared in the remaining 12 animals. In animals with profound electrophysiologic changes, bulging or rupture of Reissner's membrane and damaged hair cells were observed. These findings suggest that an abrupt change in perilymphatic pressure produces morphologic changes in the membranous labyrinth, causing changes in the vibration function of the cochlear partition and in the function of the organ of Corti. Abrupt pressure imbalance may be a causative factor of sensorineural hearing loss in the case of perilymphatic fistula.

Evaluation of the effects of lymph drainage by a thoracic duct fistula in experimental peritonitis

Previous studies suggest that systemic endotoxemia in peritonitis is mainly related to lymphatic transport via the thoracic duct. Rats with fecal peritonitis but with or without a lymph draining thoracic duct fistula were studied with reference to the concentrations of endogenously produced endotoxin in arterial plasma, hemodynamic parameters, organ blood flow, blood corpuscle parameters, glucose and lactate metabolism and survival. Lymph drainage significantly reduced the endotoxin concentrations in arterial plasma, but did not totally prevent systemic endotoxemia, and was related to maintained total peripheral vascular resistance. On the other hand, peritonitic rats without lymph drainage, and consequently higher endotoxin concentrations, had a significant fall in vascular resistance combined with a compensatory rise in cardiac output. Lymph drainage also contributed to a smaller decrease of platelet and leucocyte counts while no effect was observed on glucose metabolism. Despite the effect of lymph drainage on hemodynamic and hematologic responses no effect on survival time was recorded.

Ultra-high-frequency jet ventilation in a bronchopleural fistula model

High-frequency ventilation techniques have been demonstrated to be useful in decreasing gas loss from bronchopleural fistulas. We performed the present study to evaluate the impact of a new jet ventilator design and ventilatory frequency on hemodynamics, gas exchange, and bronchialstump gas flow in an animal model of bronchopleural fistula. Ten pigs underwent a right-sided thoracotomy and right-sided upper pulmonary lobectomy with cannulation of the upper lobe bronchus for measurement of bronchial fistula flow rate. Animals underwent a random sequence of conventional ventilation (12 to 20 breaths per minute), conventional high-frequency jet ventilation (120 breaths per minute), and ultra-high-frequency jet ventilation (UHFJV; 450 breaths per minute). Hemodynamic measurements were similar in the three ventilatory modes, but oxygenation was best with UHFJV. Bronchial fistula flow was lowest with UHFJV and greatest with conventional ventilation. Ultra-high-frequency jet ventilation demonstrated superior oxygen loading, adequate carbon dioxide elimination, and the least flow through the fistula, suggesting that both ventilator design and frequency are important therapeutic variables in the management of major airway disruption.

Effects of hypobaria on lung fluid balance in awake sheep

Effects of hypobaria on lung fluid balance were studied in five awake sheep with chronic lung lymph fistulas using a decompression chamber. Each sheep was exposed to three conditions of 6,600-m-simulated high altitude in random order as follows: 1) 6,600-m-simulated hypoxic hypobaria (barometric pressure 326 Torr, 21% inspired O2 fraction), 2) 6,600-m-simulated normoxic hypobaria (barometric pressure 326 Torr, 65% inspired O2 fraction), and 3) 6,600-m-simulated normoxic hypobaria (barometric pressure 326 Torr, 65% inspired O2 fraction) after pretreatment with a 2-h pure O2 inhalation (i.e., denitrogenation) to allow elimination of dissolved gases, especially N2, from the blood and tissues. We observed that under both hypoxic hypobaria and normoxic hypobaria, lung lymph flow (Qlym) significantly increased from the base-line values of 6.4 +/- 0.3 to 13.0 +/- 1.0 ml/h and 6.0 +/- 0.2 to 9.4 +/- 0.3 ml/h, respectively (P less than 0.05) and that the lymph-to-plasma protein concentration ratio remained unchanged. Moreover, pretreatment with a 2-h denitrogenation inhibited the increase in Qlym. These results suggest that rapid exposure to hypobaria causes an increase in pulmonary vascular permeability and that intravascular air bubble formation may account for this permeability change.

Development of pressure monitoring and controlling system for quantitative analysis of experimentally induced perilymph fistula

The cause of perilymph fistula, a subgroup of sudden deafness, has not been clearly understood. To study its etiology quantitatively, the inner ear pressure monitoring system with a computer controlled pressurizing device and three types of low-pressure monitoring sensors was constructed and utilized in ex vivo experiments using white guinea pigs. Hypothesizing that cerebrospinal pressure increases cause rupture of the round window membrane, direct and indirect pressurization to cerebrospinal region and simultaneous measurement of inner ear and cerebrospinal pressures were carried out. Ruptures of the round window membranes were seen in the experiments with direct saline infusion into the cochlea when the increment of inner ear pressure exceeded 500 mmH2O. There was no sign of rupture when squeezing abdomen was employed as an indirect pressurization, although cerebrospinal pressure increased.

Pressure transmission properties from the externa ear canal to the inner ear. An experimental study using guinea pigs

The inner ear pressure (PIE) in response to pressure changes in the external ear canal was measured in guinea pigs while alternatively opening and closing the perforation of the otic bulla. When the bulla was opened, only a transient degree of applied pressure was transmitted to the inner ear and the amplitude of the PIE was smaller than that of the corresponding PIE when the bulla was closed. This was because the applied pressure was exclusively transmitted to the inner ear via the ossicular chain. When the otic bulla was closed, the pressure was transmitted not only via the ossicular chain but also via the round window (RW) through the middle ear cavity. When the bulla was closed, the amplitude of PIE was larger by a positive pressure load than by the corresponding negative one. The amplitude of PIE showed a linear relationship to ear canal pressure of at least within the +/- 200 mmH2O range, as long as pressure was slowly applied to the ear canal. When the loading pressure was abruptly changed, a bouncing response, possibly reflecting elasticity of the RW, was evoked, which diminished or disappeared when the round window was artificially ruptured.

Gas flow through a bronchopleural fistula. Measuring the effects of high-frequency jet ventilation and chest-tube suction

High-frequency jet ventilation (HFJV) is FDA-approved for ventilating patients with bronchopleural fistulae (BPF), yet little is known about its effect on the fistula airleak. We quantitated a patient's BPF airleak during both conventional volume-cycled ventilation and HFJV. The effect of chest-tube suction (CTS) on BPF flow was also studied. Despite a significant reduction in peak airway pressure, the HFJV resulted in a 50-70 percent increase in BPF flow. CTS also significantly increased the airleak. HFJV may not always be the preferential method for ventilating patients with BPF and we recommend measuring the fistula airleak when attempting to optimize a patient's ventilatory parameters.

[Rupture of the membrane of the round window in stapes fixation]

A case of sudden deafness is described. Examination showed a mixed deafness on the left side, suspected to be due to fixation of the stapes and a simultaneous perilymph fistula. These lesions were proved by an exploratory tympanotomy. The interesting aspects of the case are emphasized: firstly recruitment caused by a perilymph fistula, present for 5 months without causing complete deafness; secondly improvement of hearing after surgical treatment of both pathological conditions; and finally the complete absence of vestibular signs.

The maintenance of total ventilatory requirements through a chronic bronchopleural cutaneous fistula

In patient with a chronic post-tuberculous bronchopleural cutaneous fistula (BPCF), minute ventilation, dead space, flow rates, arterial blood gas tensions, and oxygen consumption were measured during mouth breathing and after 30 min of steady-state breathing solely through the BPCF. Despite a 390-ml (18%) decrease in dead space when breathing took place through the BPCF, there were no significant changes in minute ventilation or respiratory rate. BPCF breathing was also associated with an increase in airways resistance as reflected by a 300-ml (35%) decrease in the FEV1 and a 16% decrease in the FEV1/FVC ratio. The increased resistance resulted in a 20 ml/min (18%) increase in oxygen consumption. Arterial blood gas tensions remained constant. We conclude that although ventilatory efficiency was not improved, this patient was able to satisfy his total minute ventilatory requirements, for the 30-min period, solely through BPCF breathing.

Fluid flow in the cochlear aqueduct and cochlea-hydrodynamic considerations in perilymph fistula, stapes gusher, and secondary endolymphatic hydrops

There is convincing evidence that the cochlear aqueduct is normally patent in humans and is of relatively constant size. It probably plays an important role in the balance between the perilymphatic, endolymphatic, and cerebrospinal fluid pressures. The flow rate of liquids through tubes is a linear function of pressure, viscosity, and length of the tube but is a fourth degree power function of the radius of the lumen. For this reason, the radius is the most critical factor determining the flow rate. Small variations in size of the cochlear aqueduct can cause very large variations in flow rate through it.

Influence of palatal fistulas on velopharyngeal movements: a cineradiographic study

Ten patients with hard palate fistulas and velopharyngeal incompetence were examined cineradiographically with lateral and frontal projections during connected speech. The purpose was to study velopharyngeal function for open versus covered fistulas. Fistula length, width, and size were measured. With an open fistula, the degree of lateral pharyngeal wall activity was significantly correlated at the 0.05 level to fistula size. There was no statistically significant correlation between fistula size and the degree of velar activity. With the fistula covered, the velopharyngeal movements improved or even normalized in all patients regardless of fistula size. These findings indicate that patients with both velopharyngeal incompetence and an additional fistula will need covering of the fistula. If velopharyngeal incompetence persists after a temporary covering of the fistula, a combination of velopharyngeal flap surgery and fistula covering ought to be performed to normalize the velopharyngeal activity and speech and resonance.

Acute effect of paraquat on lung fluid balance and prostanoid production in awake sheep

Paraquat, a widely used herbicide, causes severe lung damage in humans and laboratory animals. Pulmonary edema is a common initial feature of paraquat toxicity, but its pathophysiology is not well understood. The purpose of this investigation was to determine the acute toxic effect of paraquat (30 mg/kg) on pulmonary transvascular protein and fluid fluxes, histologic features, and prostanoid production, using awake sheep with chronic lung lymph fistulas (n = 6). Lung lymph flow increased significantly 3.5 h after intravenous infusion of paraquat and rose to 2.6 times baseline within 8 h (from 4.4 +/- 0.4 to 11.4 +/- 1.5 ml/h, p less than 0.05). Lymph-plasma protein concentration ratio increased during the same time period (from 0.64 +/- 0.05 to 0.75 +/- 0.04, p less than 0.05). Lung lymph protein clearance also increased at 3.5 h and remained elevated throughout the duration of the experiment. Pulmonary arterial and left atrial pressure were only slightly altered. Plasma and lung lymph thromboxane A2 (as TXB2) concentrations were significantly increased at 30 min and continued so thereafter. Plasma and lung lymph prostacyclin (6-keto-PGF1 alpha) concentrations increased significantly at 3 h and were more than 5 times baseline by 7 h. The time course of the increase in 6-keto-PGF1 alpha concentrations seemed similar to that of lung lymph flow. The high flow of protein-rich lymph strongly suggested an increase in pulmonary vascular permeability, which may indicate pulmonary endothelial damage. Histologic studies of the lungs revealed only minor changes in perivascular cuffing, minimal alveolar hemorrhage, and slight neutrophilic alveolar wall infiltration.(ABSTRACT TRUNCATED AT 250 WORDS)