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ABSTRACT: A perilymphatic fistula (PLF) is an abnormal communication between the inner and middle ear resulting in vestibular or cochlear symptoms. We review three pediatric traumatic temporal bone fractures with pneumolabyrinth, confirmed radiologically by the presence of air within the cochlea (pneumocochlea) or vestibule (pneumovestibule). Patients were treated conservatively with complete resolution of vestibulopathy. Hearing outcome was variable and worse in two patients with pneumocochlea. A pneumolabyrinth on radiologic imaging confirms a PLF and obviates the need for exploration to reach a diagnosis. We suggest exploration be reserved for patients with persisting cerebrospinal fluid leakage, progressive sensorineural hearing loss, or vestibular symptomatology.
The Laryngoscope 02/2011; 121(4):856-9. · 1.75 Impact Factor
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ABSTRACT: Congenital bilateral vocal fold paralysis (BVP) is a rare but serious condition often requiring a tracheostomy to temporize the airway. In cases of idiopathic BVP, studies suggest waiting twelve months prior to laryngeal surgery because of a high rate of spontaneous recovery. Therefore a less invasive and reversible intervention would be optimal. A prospective study in a piglet model was undertaken to evaluate the efficacy of a novel spring-loaded stenting device designed to maintain laryngeal patency in an in vivo animal model of BVP.
Eight Yorkshire piglets had BVP induced by surgical division of the recurrent laryngeal nerves. Stents were endoscopically deployed between the arytenoid vocal processes. Animals were recovered and monitored for stridor, dietary intake, and weight gain. Animals were sacrificed after five days. Airway resistance using a calibrated manometer was measured at four time-points: baseline, BVP induction, stent insertion, and pre-sacrifice.
Six of eight animals survived greater than five days with an average weight gain of 1.9kg (p=0.003). Relative inspiratory resistance increased from baseline after inducing BVP (1.00 vs. 1.468, p=0.0315) and decreased to baseline levels with stent insertion (1.468 vs. 1.092, p=0.0238). Expiratory resistance was not significantly influenced by stage of measurement (p=0.236). Of the two animals not surviving the protocol, one had an unrelated anesthesia complication and the other a malpositioned stent.
The novel stent was successful in relieving the inspiratory resistance associated with BVP, without compromising swallowing and daily function. This may hold promise in temporarily securing the pediatric airway in the setting of BVP.
International journal of pediatric otorhinolaryngology 11/2010; 75(2):182-5. · 0.85 Impact Factor
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M Slessarev, E Prisman,
S Ito,
R R Watson,
D Jensen,
D Preiss,
R Greene,
T Norboo,
T Stobdan,
D Diskit,
A Norboo,
M Kunzang,
O Appenzeller,
J Duffin,
J A Fisher
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ABSTRACT: We compared the control of breathing of 12 male Himalayan highlanders with that of 21 male sea-level Caucasian lowlanders using isoxic hyperoxic ( = 150 mmHg) and hypoxic ( = 50 mmHg) Duffin's rebreathing tests. Highlanders had lower mean +/- s.e.m. ventilatory sensitivities to CO(2) than lowlanders at both isoxic tensions (hyperoxic: 2.3 +/- 0.3 vs. 4.2 +/- 0.3 l min(1) mmHg(1), P = 0.021; hypoxic: 2.8 +/- 0.3 vs. 7.1 +/- 0.6 l min(1) mmHg(1), P < 0.001), and the usual increase in ventilatory sensitivity to CO(2) induced by hypoxia in lowlanders was absent in highlanders (P = 0.361). Furthermore, the ventilatory recruitment threshold (VRT) CO(2) tensions in highlanders were lower than in lowlanders (hyperoxic: 33.8 +/- 0.9 vs. 48.9 +/- 0.7 mmHg, P < 0.001; hypoxic: 31.2 +/- 1.1 vs. 44.7 +/- 0.7 mmHg, P < 0.001). Both groups had reduced ventilatory recruitment thresholds with hypoxia (P < 0.001) and there were no differences in the sub-threshold ventilations (non-chemoreflex drives to breathe) between lowlanders and highlanders at both isoxic tensions (P = 0.982), with a trend for higher basal ventilation during hypoxia (P = 0.052). We conclude that control of breathing in Himalayan highlanders is distinctly different from that of sea-level lowlanders. Specifically, Himalayan highlanders have decreased central and absent peripheral sensitivities to CO(2). Their response to hypoxia was heterogeneous, with the majority decreasing their VRT indicating either a CO(2)-independent increase in activity of peripheral chemoreceptor or hypoxia-induced increase in [H(+)] at the central chemoreceptor. In some highlanders, the decrease in VRT was accompanied by an increase in sensitivity to CO(2), while in others VRT remained unchanged and their sub-threshold ventilations increased, although these were not statistically significant.
The Journal of Physiology 03/2010; 588(Pt 9):1591-606. · 4.72 Impact Factor
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Guoqiang Xing,
Clifford Qualls,
Luis Huicho,
Maria Rivera-Ch,
Tsering Stobdan,
Marat Slessarev, Eitan Prisman,
Shoji Ito,
Hong Wu,
Angchuk Norboo, [......],
Moses Kunzang,
Tsering Norboo,
Jorge L Gamboa,
Victoria E Claydon,
Joseph Fisher,
Guta Zenebe,
Amha Gebremedhin,
Roger Hainsworth,
Ajay Verma,
Otto Appenzeller
PLoS ONE 02/2008; 3(6). · 4.09 Impact Factor
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ABSTRACT: To assess the effect of changes in end-tidal partial pressure of O(2) (PETO(2)) on cerebrovascular reactivity (CVR) estimated from changes in blood oxygen level-dependent (BOLD) signal during cyclic changes in end-tidal partial pressure of CO(2) (PETCO(2)).
BOLD response to fixed cyclic step changes in PETCO(2) (range = 30.4-48.8 mmHg) and PETO(2) (range = 100.6-444.0 mmHg) was studied in four healthy volunteers.
The BOLD reactivity to PETCO(2) and PETO(2) were 0.283 (0.188-0.379) (median, range) and 0.004 (0.003-0.006)%/mmHg, respectively, in the whole brain; 0.438 (0.382-0.614) vs. 0.006 (0.004-0.009)%/mmHg, respectively, in the gray matter; and 0.075 (0.065-0.093) vs. 0.002 (0.001-0.002)%/mmHg, respectively, in the white matter.
The BOLD reactivity to PETO(2) was much smaller than that to PETCO(2). However, BOLD reactivity can be significantly distorted by CO(2)-induced changes in PETO(2). We conclude that PETO(2) should be carefully controlled during studies that use BOLD reactivity as an indicator of CVR.
Journal of Magnetic Resonance Imaging 02/2008; 27(1):185-91. · 2.70 Impact Factor
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Guoqiang Xing,
Clifford Qualls,
Luis Huicho,
Maria Rivera-Ch,
Maria River-Ch,
Tsering Stobdan,
Marat Slessarev, Eitan Prisman,
Shoji Ito,
Soji Ito, [......],
Moses Kunzang,
Tsering Norboo,
Jorge L Gamboa,
Victoria E Claydon,
Joseph Fisher,
Guta Zenebe,
Amha Gebremedhin,
Roger Hainsworth,
Ajay Verma,
Otto Appenzeller
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ABSTRACT: The study of the biology of evolution has been confined to laboratories and model organisms. However, controlled laboratory conditions are unlikely to model variations in environments that influence selection in wild populations. Thus, the study of "fitness" for survival and the genetics that influence this are best carried out in the field and in matching environments. Therefore, we studied highland populations in their native environments, to learn how they cope with ambient hypoxia. The Andeans, African highlanders and Himalayans have adapted differently to their hostile environment. Chronic mountain sickness (CMS), a loss of adaptation to altitude, is common in the Andes, occasionally found in the Himalayas; and absent from the East African altitude plateau. We compared molecular signatures (distinct patterns of gene expression) of hypoxia-related genes, in white blood cells (WBC) from Andeans with (n = 10), without CMS (n = 10) and sea-level controls from Lima (n = 20) with those obtained from CMS (n = 8) and controls (n = 5) Ladakhi subjects from the Tibetan altitude plateau. We further analyzed the expression of a subset of these genes in Ethiopian highlanders (n = 8). In all subjects, we performed the studies at their native altitude and after they were rendered normoxic. We identified a gene that predicted CMS in Andeans and Himalayans (PDP2). After achieving normoxia, WBC gene expression still distinguished Andean and Himalayan CMS subjects. Remarkably, analysis of the small subset of genes (n = 8) studied in all 3 highland populations showed normoxia induced gene expression changes in Andeans, but not in Ethiopians nor Himalayan controls. This is consistent with physiologic studies in which Ethiopians and Himalayans show a lack of responsiveness to hypoxia of the cerebral circulation and of the hypoxic ventilatory drive, and with the absence of CMS on the East African altitude plateau.
PLoS ONE 01/2008; 3(6):e2342. · 4.09 Impact Factor
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ABSTRACT: Carbogen has long been under investigation as an adjuvant to radiotherapy of tumors. A major factor confounding its evaluation is its inconsistency in raising blood partial pressure of CO(2) (pCO(2)). We investigated whether a new partial rebreathing method would provide better control of pCO(2) than carbogen.
We compared the efficacy of each method in 10 healthy volunteers. Volunteers breathed 1.5, 3 and 5% carbogen in 5-min stages via the usual non-rebreathing circuit. All the volunteers then breathed 100% O(2) through a commercial sequential gas delivery (SGD) circuit modified by attaching a reservoir to its exhalation port. Hypercarbia was induced by step reductions in oxygen flow to the SGD circuit. We monitored minute ventilation and end-tidal pCO(2) (ETpCO(2)) as a surrogate for its arterial value.
Inhalation of 1.5 and 3% carbogen did not increase ETpCO(2) from baseline (40 +/- 1.5 mmHg); 5% carbogen increased ETpCO(2) to 45 +/- 1.6 mmHg (p < 0.001). With the SGD circuit, reducing O(2) flow to 4.3 +/- 0.7 l/min increased ETpCO(2) in all subjects from 41 +/- 2.0 mmHg (baseline) to 46 +/- 2.1 mmHg (p < 0.001). Voluntary hyperventilation reduced ETpCO(2) with 5% carbogen but not with SGD (p = 0.379).
We confirm previous observations that carbogen inhalation does not result in a predictable rise in ETpCO(2) and suggest that a precise and stable target ETpCO(2) can instead be induced by simply controlling O(2) flow into a modified SGD circuit. We hoped that the reliable control of pCO(2) will enable studies that address first, the efficacy of raising ETpCO(2) on specific tumor blood flow, and eventually, its benefit as an adjuvant to radiotherapy.
International Journal of Radiation Biology 07/2007; 83(7):457-62. · 2.28 Impact Factor
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ABSTRACT: Current methods of forcing end-tidal PCO2 (PETCO2) and PO2 (PETO2) rely on breath-by-breath adjustment of inspired gas concentrations using feedback loop algorithms. Such servo-control mechanisms are complex because they have to anticipate and compensate for the respiratory response to a given inspiratory gas concentration on a breath-by-breath basis. In this paper, we introduce a low gas flow method to prospectively target and control PETCO2 and PETO2 independent of each other and of minute ventilation in spontaneously breathing humans. We used the method to change PETCO2 from control (40 mmHg for PETCO2 and 100 mmHg for PETO2) to two target PETCO2 values (45 and 50 mmHg) at iso-oxia (100 mmHg), PETO2 to two target values (200 and 300 mmHg) at normocapnia (40 mmHg), and PETCO2 with PETO2 simultaneously to the same targets (45 with 200 mmHg and 50 with 300 mmHg). After each targeted value, PETCO2 and PETO2 were returned to control values. Each state was maintained for 30 s. The average difference between target and measured values for PETCO2 was +/-1 mmHg, and for PETO2 was +/-4 mmHg. PETCO2 varied by +/-1 mmHg and PETO2 by +/-5.6 mmHg (s.d.) over the 30 s stages. This degree of control was obtained despite considerable variability in minute ventilation between subjects (+/-7.6 l min(-1)). We conclude that targeted end-tidal gas concentrations can be attained in spontaneously breathing subjects using this prospective, feed-forward, low gas flow system.
The Journal of Physiology 07/2007; 581(Pt 3):1207-19. · 4.72 Impact Factor
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ABSTRACT: We present the principles of a new method to calculate O2 consumption (V*O2) during low-flow anesthesia with a circle circuit when the source gas flows, end-tidal O2 concentrations and patient inspired minute ventilation are known. This method was tested in a model with simulated O2 uptake and CO2 production. The difference between calculated V*O2 and simulated V*O2 was 0.01 +/- 0.02 L/min. A similar approach can be used to calculate uptake of inhaled anesthetics. At present, with this method, the limiting factor in precision of measurement of V*O2 and uptake of anesthetic is the precision of measurement of gas flow and gas concentration (especially O2 concentration in end-tidal gas, FETO2) available in clinical anesthetic units.
Journal of Clinical Monitoring and Computing 01/2005; 18(5-6):325-32. · 0.89 Impact Factor
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Guoqiang Xing,
Clifford Qualls,
Luis Huicho,
Maria Rivera-Ch,
Tsering Stobdan,
Marat Slessarev, Eitan Prisman,
Shoji Ito,
Hong Wu,
Angchuk Norboo, [......],
Moses Kunzang,
Tsering Norboo,
Jorge L Gamboa,
Victoria E Claydon,
Joseph Fisher,
Guta Zenebe,
Amha Gebremedhin,
Roger Hainsworth,
Ajay Verma,
Otto Appenzeller
