Airway Occlusion Research Articles

A case series on lung deposition analysis of inhaled medication using functional imaging based computational fluid dynamics in asthmatic patients: effect of upper airway morphology and comparison with in vivo data

Context: Asthma affects 20 million Americans resulting in an economic burden of approximately $18 billion in the US alone (Allergies and Asthma Foundation 2000; National Center for Environmental Health (NCEH) 1999). Research studies based on differences in patient-specific airway morphology for asthma and the associated effect on deposition of inhaled aerosols are currently not available in the literature. Therefore, the role of morphological variations such as upper airway (extrathoracic) occlusion is not well documented.Objective: Functional imaging based computational fluid dynamics (CFD) of the respiratory airways for five asthmatic subjects is performed in this study using computed tomography (CT) based patient-specific airway models and boundary conditions.Methods: CT scans for 5 asthma patients were used to reconstruct 3D lung models using segmentation software. An averaged inhalation profile and patient-specific lobar flow distribution were used to perform the simulation. The simulations were used to obtain deposition for BDP/Formoterol® HFA pMDI in the patient-specific airway models.Results: The lung deposition obtained using CFD was in excellent agreement with available in vivo data using the same product. Specifically, CFD resulted in 30% lung deposition, whereas in vivo lung deposition was reported to be approximately 31%.Conclusion: It was concluded that a combination of patient-specific airway models and lobar boundary conditions can be used to obtain accurate lung deposition estimates. Lower lung deposition can be expected for patients with higher extrathoracic resistance. Novel respiratory drug delivery devices need to accommodate population sub-groups based on these morphological and anatomical differences in addition to subject age.

The Airway Occlusion Pressure During Upper Extremity Exercise in Healthy Adults: Differences between Supported and Unsupported Arm Exercise

The Airway Occlusion Pressure During Upper Extremity Exercise in Healthy Adults: Differences between Supported and Unsupported Arm Exercise

The Correlations of the Six-minute Walk Test and Respiratory Functions in Chronic Obstructive Pulmonary Disease Patients with Chronic Hypercapnia

Background Dyspnea and related disabling symptoms are common in chronic obstructive pulmonary disease (COPD) patients with chronic hypercapnia. Unfortunately, the indicators during the six-minute walk test (6MWT) for prediction of respiratory functions or exercise intolerance in severe COPD has been little investigated. The relationship between parameters during the 6MWT and respiratory functions was therefore assessed in COPD patients with chronic hypercapnia. Methods In 2002 and 2003, 37 COPD outpatients with chronic hypercapnia performed the 6MWT, and their respiratory function was measured. Twenty-eight males and nine females with COPD (mean forced expiratory volume in the first second of 26.1% of the predicted value, SD 7.7%) and hypercapnia (mean PaCO2 of 55.5 mmHg, SD 6.4 mmHg) were recruited. All patients were tested to measure pulmonary function, respiratory drive (airway occlusion pressure at 100 ms, P0.1), and respiratory muscle strength on the first day. On the second day, arterial blood gas analysis and the 6MWT were performed. Pearson’s correlation coefficient and regression analysis were used for data analysis. Results The study showed that the six-minute walk distance (6MWD) was weakly correlated with the resting arterial oxygen partial pressure (PaO2) (r = 0.349, p = 0.034), expiratory muscle strength (Pemax) (r = 0.358, p = 0.030), and changes of dyspnea sensation (∆Borg) (r = 0.385, p = 0.019); furthermore, ∆Borg was weakly correlated with Pemax (r = 0.377, p = 0.021). The oxygen saturation measured at the end of the 6MWT (ExSpO2) was significantly correlated with FEV1/FVC (r = −0.443, p = 0.006), pH (r = 0.375, p = 0.022), arterial carbon dioxide partial pressure (PaCO2) (r = −0.470, p = 0.003), PaO2 (r = 0.664, p = 0.000) and P0.1 (r = −0.344, p = 0.037). The results of the multiple linear regression with the 6MWD as the dependent variable revealed that PaO2, Pemax, and ∆Borg were significant determinants of the 6MWD (p = 0.018, adjusted R2 = 0.259). Conclusion Measurement of the 6MWT demonstrated that a stronger association of exercise limitation is the value of ∆Borg in COPD patients with chronic hypercapnia. Ventilation constraints, hypoxemia, hypercapnia, and respiratory drive might be associated with oxygen desaturation during the 6MWT in COPD patients with chronic hypercapnia.

Use of weekly 4DCT-based ventilation maps to quantify changes in lung function for patients undergoing radiation therapy

A method has been proposed to calculate ventilation maps from four-dimensional computed tomography (4DCT) images. Weekly 4DCT data were acquired throughout the course of radiation therapy for patients with lung cancer. The purpose of our work was to use ventilation maps calculated from weekly 4DCT data to study how ventilation changed throughout radiation therapy. Quantitative maps representing ventilation were generated for six patients. Deformable registration was used to link corresponding lung volume elements between the inhale and exhale phases of the 4DCT dataset. Following spatial registration, corresponding Hounsfield units were input into a density-change-based model for quantifying the local ventilation. The ventilation data for all weeks were registered to the pretreatment ventilation image set. We quantitatively analyzed the data by defining regions of interest (ROIs) according to dose (V(20)) and lung lobe and by tracking the weekly ventilation of each ROI throughout treatment. The slope of the linear fit to the weekly ventilation data was used to evaluate the change in ventilation throughout treatment. A positive slope indicated an increase in ventilation, a negative slope indicated a decrease in ventilation, and a slope of 0 indicated no change. The dose ROI ventilation and slope data were used to study how ventilation changed throughout treatment as a function of dose. The lung lobe ROI ventilation data were used to study the impact of the presence of tumor on pretreatment ventilation. In addition, the lobe ROI data were used to study the impact of tumor reduction on ventilation change throughout treatment. Using the dose ROI data, we found that three patients had an increase in weekly ventilation as a function of dose (slopes of 1.1, 1.4, and 1.5) and three patients had no change or a slight decrease in ventilation as a function of dose (slopes of 0.3, -0.6, -0.5). Visually, pretreatment ventilation appeared to be lower in the lobes that contained tumor. Pretreatment ventilation was 39% for lobes that contained tumor and 54% for lobes that did not contain tumor. The difference in ventilation between the two groups was statistically significant (p = 0.017). When the weekly lobe ventilation data were qualitatively observed, two distinct patterns emerged. When the tumor volume in a lobe was reduced, ventilation increased in the lobe. When the tumor volume was not reduced, the ventilation distribution did not change. The average slope of the group of lobes that contained tumors that shrank was 1.18, while the average slope of the group that did not contain tumors (or contained tumors that did not shrink) was -0.32. The slopes for the two groups were significantly different (p = 0.014). We did not find a consistent pattern of ventilation change as a function of radiation dose. Pretreatment ventilation was significantly lower for lobes that contained tumor, due to occlusion of the central airway. The weekly lobe ventilation data indicated that when tumor volume shrinks, ventilation increases, and when the thoracic anatomy is not visibly changed, ventilation is likely to remain unchanged.

Effects of airway occlusion on breathing muscle electromyogram signals, during isoflurane anaesthesia, with and without the effects of fentanyl and hypercapnia

Expiratory muscle action is prominent during anaesthesia and can impair lung function. This activity is exaggerated by the use of opioids. Airway pressure during occlusion of expiration would be a valuable measure in the study of expiratory muscle activation. However, this would only be valid if the imposed occlusion did not itself alter muscle activation. This possibility can be checked by directly assessing muscle activity by electromyography; varying arterial carbon dioxide tensions and opioid action should be considered. We studied seven spontaneously breathing patients, anaesthetized with nitrous oxide and isoflurane, in four conditions: during an infusion of fentanyl and after naloxone, breathing normally and with breathing stimulated with CO(2). We compared diaphragm and external oblique abdominal electromyogram (EMG) signals during normal and occluded breaths. We also measured chest wall volume and compared airway occlusion pressure, during inspiration and expiration, with the EMG results. Inspiratory occlusion increased the duration of inspiration during hypercapnia by 20%, but not the rate of electrical activation of the diaphragm, indicating that occlusion does not cause a reflex increase in diaphragm contraction. In contrast, expiratory occlusion did not affect either the duration of expiration or the electrical activity of the external oblique muscles. In these conditions, except for a change in inspiratory duration, respiratory muscle activity is unaffected by airway occlusion. Airway occlusion will permit valid measures of muscle activity in inspiration and expiration and provide simple measurements of respiratory muscle function during anaesthesia.

Do Commonly Used Ventilator Settings for Mechanically Ventilated Adults Have the Potential to Embed Secretions or Promote Clearance?

Intubation and mechanical ventilation can impair mucociliary clearance and cause secretion retention, airway occlusion, atelectasis, and pneumonia. Animal and laboratory work has demonstrated that mechanical ventilator settings can generate a flow bias (inspiratory or expiratory) that may result in mucus movement either away from the ventilator (deeper into the lungs) or toward the ventilator (toward the mouth), respectively. An absolute difference of 17 L/min, and a relative difference of ≥ 10%, between the expiratory and inspiratory flow have been reported as thresholds for mucus movement. We measured baseline peak inspiratory and expiratory flows during quiet mechanical ventilation in a convenience sample of 20 intubated and ventilated adult patients. Nineteen patients had an inspiratory flow bias of ≥ 10%. Eight patients had an absolute mean inspiratory flow bias of ≥ 17 L/min. Commonly used mechanical ventilator settings generate an inspiratory flow bias that may promote secretion retention.

Lagrangian transport properties of pulmonary interfacial flows

Disease states characterized by airway fluid occlusion and pulmonary surfactant insufficiency, such as respiratory distress syndrome, have a high mortality rate. Understanding the mechanics of airway reopening, particularly involving surfactant transport, may provide an avenue to increase patient survival via optimized mechanical ventilation waveforms. We model the occluded airway as a liquid-filled rigid tube with the fluid phase displaced by a finger of air that propagates with both mean and sinusoidal velocity components. Finite-time Lyapunov exponent (FTLE) fields are employed to analyse the convective transport characteristics, taking note of Lagrangian coherent structures (LCSs) and their effects on transport. The Lagrangian perspective of these techniques reveals flow characteristics that are not readily apparent by observing Eulerian measures. These analysis techniques are applied to surfactant-free velocity fields determined computationally, with the boundary element method, and measured experimentally with micro particle image velocimetry (μ-PIV). We find that the LCS divides the fluid into two regimes, one advected upstream (into the thin residual film) and the other downstream ahead of the advancing bubble. At higher oscillatory frequencies particles originating immediately inside the LCS experience long residence times at the air-liquid interface, which may be conducive to surfactant transport. At high frequencies a well-mixed attractor region is identified; this volume of fluid cyclically travels along the interface and into the bulk fluid. The Lagrangian analysis is applied to velocity data measured with 0.01 mg ml(-1) of the clinical pulmonary surfactant Infasurf in the bulk fluid, demonstrating flow field modifications with respect to the surfactant-free system that were not visible in the Eulerian frame.

Laryngeal dystonia in the course of multiple system atrophy: a cause of postoperative respiratory insufficiency

Multiple system atrophy (MSA) is an adult onset, incurable neurodegenerative disease, characterized by symptoms of nervous system failure. Occurrence of laryngeal dystonia indicates increased risk of sudden death caused by airway occlusion. We present the case report of 63-year-old patient with history of orthostatic hypotension, parkinsonism, progressive adynamia, and stridor. The patient was admitted to the hospital for diagnosis of orthostatic hypotension. A diagnosis of possible MSA was made. Because of patient’s complaints, an X-ray of the hip joint was taken. It revealed femoral neck fracture. Endoprosthesis insertion under general anesthesia was performed. Two days later the patient presented progressive adynamy and respiratory insufficiency. Endotracheal intubation and respiratory support were required followed by extubation and one more intubation. After second extubation, stridor and acute respiratory insufficiency occurred. Urgent tracheostomy was performed. After 13 days in ICU, the patient was discharged to the rehabilitation center.

Animal‐Related Fatalities—Part II: Characteristic Autopsy Findings and Variable Causes of Death Associated with Envenomation, Poisoning, Anaphylaxis, Asphyxiation, and Sepsis

In addition to blunt and sharp trauma, animal-related fatalities may result from envenomation, poisoning, anaphylaxis, asphyxiation, and sepsis. Although the majority of envenomation deaths are caused by hornets, bees, and wasps, the mechanism of death is most often anaphylaxis. Envenomation resulting from the injection of a poison or toxin into a victim occurs with snakes, spiders, and scorpions on land. Marine animal envenomation may result from stings and bites from jellyfish, octopus, stonefish, cone fish, stingrays, and sea snakes. At autopsy, the findings may be extremely subtle, and so a history of exposure is required. Poisoning may also occur from ingesting certain fish, with three main forms of neurotoxin poisoning involving ciguatera, tetrodotoxin ingestion, and paralytic shellfish poisoning. Asphyxiation may follow upper airway occlusion or neck/chest compression by animals, and sepsis may follow bites. Autopsy analysis of cases requires extensive toxinological, toxicological, and biochemical analyses of body fluids.

Observations on the Study of Second Gas Effects

Observations on the Study of Second Gas Effects

Parâmetros preditivos para o desmame da ventilação mecânica

The use of predictive parameters for weaning from mechanical ventilation is a rather polemic topic, and the results of studies on this topic are divergent. Regardless of the use of these predictive parameters, the spontaneous breathing trial (SBT) is recommended. The objective of the present study was to review the utility of predictive parameters for weaning in adults. To that end, we searched the Medline, LILACS, and PubMed databases in order to review articles published between 1991 and 2009, in English or in Portuguese, using the following search terms: weaning/desmame, extubation/extubação, and weaning indexes/indices de desmame. The use of clinical impression is an inexact means of predicting weaning outcomes. The most widely used weaning parameter is the RR/tidal volume (V T) ratio, although this parameter presents heterogeneous results in terms of accuracy. Other relevant parameters are MIP, airway occlusion pressure (P0.1), the P0.1/MIP ratio, RR, V T, minute volume, and the index based on compliance, RR, oxygenation, and MIP. An index created in Brazil, the integrative weaning index, has shown high accuracy. Although recommended, the SBT is inaccurate, approximately 15% of extubation failures going unidentified in SBTs. The main limitations of the weaning indexes are related to their use in specific populations, the cut-off points selected, and variations in the types of measurement. Since the SBT and the clinical impression are not 100% accurate, the weaning parameters can be useful, especially in situations in which the decision as to weaning is difficult.

Tuberculosis presenting as bilateral vocal fold palsy: case report and review of otolaryngological manifestations of tuberculosis

We report a rare case of tuberculosis presenting with bilateral vocal fold palsy. Case report and discussion of ENT manifestations of tuberculosis. A 39-year-old man presented with stridor and bilateral vocal fold palsies, and underwent an emergency tracheostomy. Intra-operatively, a mass was identified overlying the thyroid cartilage. Fine needle aspiration cytology of this mass showed well formed granulomas but negative Ziehl-Nielsen staining. Computed tomography showed the mass to be surrounding the thyroid cartilage, causing airway occlusion; pulmonary infiltrates were also seen. The patient was commenced on tuberculosis treatment. Subsequent sputum samples from the tracheostomy confirmed the diagnosis. The patient responded very well to treatment, and was successfully decannulated after one week. The incidence of tuberculosis in the UK is increasing, particularly in urban areas. The otolaryngologist may encounter a wide variety of presentations. Diagnosis requires a high index of clinical suspicion.

Paraneoplastic autoimmune multiorgan syndrome: 20 years after

The purpose of this review is to provide insight and clarification in the quandary of classification and delineate clinical and histological features and pathophysiology of paraneoplastic pemphigus. This is a paraneoplastic disease of epithelial autoimmunity and adhesion originally described by Dr. Anhalt in 1990. Paraneoplastic pemphigus represents only one manifestation of the heterogeneous autoimmune syndrome in which patients, in addition to small airways occlusion, may display a spectrum of at least five clinical variants of the mucocutaneous disease [i.e. pemphigus-like, pemphigoid-like, erythema multiforme-like, graft-versus-host disease-like, and lichen planus-like, termed paraneoplastic autoimmune multiorgan syndrome (PAMS)]. There is a need for the expanded, inclusive classification of diverse mucocutaneous and respiratory presentations of PAMS. Multiple specific effectors of humoral and cellular autoimmunity mediating epithelial damage have been identified. An update of advances in clinical and basic research on PAMS and in management and overall prognosis of PAMS is provided.

Striatal Neuroprotection from Neonatal Hypoxia-Ischemia in Piglets by Antioxidant Treatment with EUK-134 or Edaravone

Striatal neurons are highly vulnerable to hypoxia-ischemia (HI) in term newborns. In a piglet model of HI, striatal neurons develop oxidative stress and organelle disruption by 3–6 h of recovery and ischemic cytopathology over 6–24 h of recovery. We tested the hypothesis that early treatment with the antioxidants EUK-134 (a manganese-salen derivative that acts as a scavenger of superoxide, hydrogen peroxide, nitric oxide or NO and peroxynitrite) or edaravone (MCI-186, a scavenger of hydroxyl radical and NO) protects striatal neurons from HI. Anesthetized newborn piglets were subjected to 40 min of hypoxia and 7 min of airway occlusion. At 30 min after resuscitation, the piglets received vehicle, EUK-134 or edaravone. Drug treatment did not affect arterial blood pressure, blood gases, blood glucose or rectal temperature. At 4 days of recovery, the density of viable neurons in the putamen of vehicle-treated piglets was 12 ± 6% (±SD) of sham-operated control density. Treatment with EUK-134 increased viability to 41 ± 17%, and treatment with edaravone increased viability to 39 ± 19%. In the caudate nucleus, neuronal viability was increased from 54 ± 11% in the vehicle group to 78 ± 15% in the EUK-134 group and to 73 ± 13% in the edaravone group. Antioxidant drug treatment accelerated recovery from neurologic deficits and decreased oxidative and nitrative damage to nucleic acids. Treatment with EUK-134 reduced the HI-induced formation of protein carbonyl groups and tyrosine nitration at 3 h of recovery. We conclude that systemic administration of antioxidant agents by 30 min after resuscitation from HI can reduce oxidative stress and salvage neurons in the highly vulnerable striatum in a large-animal model of neonatal HI. Therefore, oxidative stress is an important mechanism for this injury, and antioxidant therapy is a rational, mechanism-based approach to neuroprotection in the newborn brain.

Aortic root size and sleep apnea in elderly: A cohort study

Recent studies have shown that obstructive sleep apnea (OSA) could affect functional and structural properties of large arteries [ [1] Tanriverdi H. Evrengul H. Kaftan A. et al. Effect of obstructive sleep apnea on aortic elastic parameters: relationship to left ventricular mass and function. Circ J. 2006; 70: 737-743 Crossref PubMed Scopus (30) Google Scholar ] and that sleep-related breathing disorders could be involved in aortic root dilatation. Several pathophysiological mechanisms could explain such a relationship. An increase of sympathetic nerve activity occurs during night in OSA, inducing repeated rises in blood pressure (BP) which may enhance the risk of aortic dilatation. Another plausible explanation relates to an increase of negative intrathoracic pressure during inspiratory efforts against occluded upper airway during apneic episodes. These pressures are transmitted to intrathoracic structures, including aorta and may favor aortic expansion [ [2] Cistulli P.A. Wilcox I. Jeremy R. Sullivan C.E. aortic root dilatation in Marfan's syndrome: a contribution from obstructive sleep apnea?. Chest. 1997; 111: 1763-1766 Crossref PubMed Scopus (35) Google Scholar ]. The aim of the present study was to evaluate in a cohort of subjects from an elderly general population, the impact of OSA on aortic root size.

Pay attention to comorbidities in chronic obstructive pulmonary disease

To evaluate the predictive performance of neuro-mechanical coupling (NMC) and neuro-ventilatory coupling (NVC) in the weaning outcome in patients with chronic obstructive pulmonary disease (COPD).Sixteen patients were enrolled when the criteria for their first spontaneous breathing trial (SBT) was met. A 30-minute SBT was attempted, with the measurement of electrical activity of the diaphragm (Edi), NMC, NVC, NVC × NMC, index of rapid shallow breathing (f/Vt), airway occlusion pressure (P(0.1)) and f/Vt × P(0.1) at 0, 5 and 30 min. The receiver operating characteristic (ROC) curve was calculated to evaluate the predictive performance of each index.Successful weaning (S group) was observed in 6 patients while weaning failure (F group) in 10 patients. (1) The predictive capacity of Edi: at 30 min of SBT, Edi showed higher values in the F group (P < 0.05), the area under the ROC curves (AUC) was 0.817(P < 0.05). (2) The predictive capacity of NVC and NMC: at 5, 30 min of SBT, NVC and NMC showed higher values in the S group (P < 0.05); at 30 min of SBT NVC presented the largest AUC than any other time of SBT (0.822, P < 0.05), while the AUC of NMC was 0.800(P > 0.05). (3) The predictive capacity of NVC × NMC: at 30 min of SBT, the AUC of NVC × NMC was larger than NVC (0.864, P < 0.05), showing greater sensitivity (100.0%) and specificity (83.3%). (4) The predictive capacity of f/Vt and P(0.1): f/Vt and f/Vt × P(0.1) presented poor predictive performance in the failed patients.Edi, NVC and NVC × NMC were good predictor for the weaning outcome in patients with COPD.

Epithelium damage and protection during reopening of occluded airways in a physiologic microfluidic pulmonary airway model

Airways of the peripheral lung are prone to closure at low lung volumes. Deficiency or dysfunction of pulmonary surfactant during various lung diseases compounds this event by destabilizing the liquid lining of small airways and giving rise to occluding liquid plugs in airways. Propagation of liquid plugs in airways during inflation of the lung exerts large mechanical forces on airway cells. We describe a microfluidic model of small airways of the lung that mimics airway architecture, recreates physiologic levels of pulmonary pressures, and allows studying cellular response to repeated liquid plug propagation events. Substantial cellular injury happens due to the propagation of liquid plugs devoid of surfactant. We show that addition of a physiologic concentration of a clinical surfactant, Survanta, to propagating liquid plugs protects the epithelium and significantly reduces cell death. Although the protective role of surfactants has been demonstrated in models of a propagating air finger in liquid-filled airways, this is the first time to study the protective role of surfactants in liquid plugs where fluid mechanical stresses are expected to be higher than in air fingers. Our parallel computational simulations revealed a significant decrease in mechanical forces in the presence of surfactant, confirming the experimental observations. The results support the practice of providing exogenous surfactant to patients in certain clinical settings as a protective mechanism against pathologic flows. More importantly, this platform provides a useful model to investigate various surface tension-mediated lung diseases at the cellular level.

Frequency‐domain analysis of diaphragm muscle EMG activity across ventilatory and non‐ventilatory motor behaviors

Diaphragm motor units are recruited in an orderly fashion across ventilatory and non-ventilatory behaviors such that slow-twitch and fatigue-resistant fast-twitch units are exclusively recruited at low levels of force whereas fatigable and intermediate fast-twitch units are additionally recruited at high force levels. In models describing the relationship between power density spectrum (PDS) of the EMG signal and average conduction velocity of active muscle fibers, as muscle fibers with higher conduction velocities are recruited, PDS of the EMG signal will shift to higher frequencies. However, there are conflicting results in the literature which depend on species, muscles involved and contraction and/or activation patterns. We hypothesized that the PDS of the diaphragm muscle EMG signal will shift to higher frequencies as diaphragm muscle activation increases across ventilatory and non-ventilatory behaviors. We found a significant increase in the ratio of high frequency components to low frequency components during expulsive non-ventilatory behaviors such as airway occlusion and sneezing compared to ventilatory behaviors such as eupnea and hypoxia-hypercapnia. These findings are consistent with additional recruitment of fatigable and intermediate fast-twitch units during motor behaviors of increasing demand.

Randomised trial comparing assist control and pressure support ventilation during weaning

AimAssist control ventilation (ACV) compared to pressure limited, time cycled ventilation is associated with shorter duration of weaning. During both ACV and pressure support ventilation (PSV), all the infant's breaths...

Low-Level Laser Therapy (LLLT) at 830 nm Positively Modulates Healing of Tracheal Incisions in Rats: A Preliminary Histological Investigation

The aim of the present study was to evaluate whether LLLT at 830 nm is able to positively modulate trachea incisional wound healing in Sprague-Dawley rats. Tracheotomy may be associated with numerous complications. Development of excess granulation tissue represents a late complication that may lead to airway occlusion. Low-level laser therapy (LLLT) has been shown to have stimulatory effects on wound healing of different tissues. Therefore, it may be suggested that LLLT could be able to positively modulate trachea wound healing as well. Using general anesthesia, a median incision was performed from the second to the fifth tracheal cartilage ring in 24 rats. Animals were then randomly divided into sham-irradiated control and laser-treated groups. LLLT (power density: 450 mW/cm(2); total daily dose: 60 J/cm(2); irradiated area ∼1 cm(2)) treatment was performed daily during the first week after surgery. Samples for histological evaluation were removed 7 and 28 days after surgical procedure. Histological sections were stained with hematoxylin-eosin and van Gieson. Results from our investigation showed that LLLT was able to reduce granulation tissue formation and simultaneously increase new cartilage development at both evaluated time intervals. From this point of view, LLLT at 830 nm may be a valuable tool in trachea wound healing modulation. Nevertheless, further detailed research is needed to find optimal therapeutic parameters and to test these findings on other animal models.