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Modulation of intraocular pressure by unilateral and forced unilateral nostril breathing in young healthy human subjects

Mohan SM, Reddy SC, Wei LY

Int Ophthalmol, 2001;24(6):305-11.
PMID: 14750567

PURPOSE: To determine the effects of unilateral right/left nostril breathing (URNB/ULNB) and forced unilateral right/left nostril breathing (FURNB/FULNB) on intraocular pressure (IOP) and to examine the differences in the IOP during the various phases of nasal cycle.
METHODS: Young healthy volunteers of either sex aged between 19-24 years, participated in the sessions using URNB/ULNB (n = 52) and FURNB/FULNB (n = 28). The nostril dominance was calculated from signals recorded on the PowerLab equipment, representing pressure changes at the end of the nostrils during respiration. The IOP was measured with Tono-Pen. The subjects were divided into 4 groups viz. right nostril dominant (RND), left nostril dominant (LND), transitional right nostril dominant (TRND) and transitional left nostril dominant (TLND) groups. The IOP data 'before and after' URNB/ULNB or FURNB/FULNB were compared by using paired t-test. The baseline data of IOP between the groups were analysed by using independent samples t-test.
RESULTS: The URNB decreased the IOP in the LND and TLND (p < 0.01) and also in the RND (p < 0.05) groups but not significantly in the TRND group. The ULNB decreased the IOP in the RND group (p < 0.01) only. The FURNB significantly reduced the IOP (p < 0.05) only in the LND and RND groups. The FULNB decreased the IOP but not significantly. The baseline IOP did not differ significantly between the LND, RND, TLND and TRND groups.
CONCLUSION: The URNB/FURNB reduced the IOP, while ULNB/FULNB failed to increase the IOP significantly. It is suggested that the lowering of IOP by URNB indicated sympathetic stimulation.

Matched MeSH terms: Respiratory Mechanics/physiology*
Fulltext Hybrid mesh for nasal airflow studies

Zubair M, Abdullah MZ, Ahmad KA

Comput Math Methods Med, 2013;2013:727362.
PMID: 23983811 DOI: 10.1155/2013/727362

The accuracy of the numerical result is closely related to mesh density as well as its distribution. Mesh plays a very significant role in the outcome of numerical simulation. Many nasal airflow studies have employed unstructured mesh and more recently hybrid mesh scheme has been utilized considering the complexity of anatomical architecture. The objective of this study is to compare the results of hybrid mesh with unstructured mesh and study its effect on the flow parameters inside the nasal cavity. A three-dimensional nasal cavity model is reconstructed based on computed tomographic images of a healthy Malaysian adult nose. Navier-Stokes equation for steady airflow is solved numerically to examine inspiratory nasal flow. The pressure drop obtained using the unstructured computational grid is about 22.6 Pa for a flow rate of 20 L/min, whereas the hybrid mesh resulted in 17.8 Pa for the same flow rate. The maximum velocity obtained at the nasal valve using unstructured grid is 4.18 m/s and that with hybrid mesh is around 4.76 m/s. Hybrid mesh reported lower grid convergence index (GCI) than the unstructured mesh. Significant differences between unstructured mesh and hybrid mesh are determined highlighting the usefulness of hybrid mesh for nasal airflow studies.

Matched MeSH terms: Respiratory Mechanics/physiology
Evaluation of model-based methods in estimating respiratory mechanics in the presence of variable patient effort

Redmond DP, Chiew YS, Major V, Chase JG

Comput Methods Programs Biomed, 2019 Apr;171:67-79.
PMID: 27697371 DOI: 10.1016/j.cmpb.2016.09.011

Monitoring of respiratory mechanics is required for guiding patient-specific mechanical ventilation settings in critical care. Many models of respiratory mechanics perform poorly in the presence of variable patient effort. Typical modelling approaches either attempt to mitigate the effect of the patient effort on the airway pressure waveforms, or attempt to capture the size and shape of the patient effort. This work analyses a range of methods to identify respiratory mechanics in volume controlled ventilation modes when there is patient effort. The models are compared using 4 Datasets, each with a sample of 30 breaths before, and 2-3 minutes after sedation has been administered. The sedation will reduce patient efforts, but the underlying pulmonary mechanical properties are unlikely to change during this short time. Model identified parameters from breathing cycles with patient effort are compared to breathing cycles that do not have patient effort. All models have advantages and disadvantages, so model selection may be specific to the respiratory mechanics application. However, in general, the combined method of iterative interpolative pressure reconstruction, and stacking multiple consecutive breaths together has the best performance over the Dataset. The variability of identified elastance when there is patient effort is the lowest with this method, and there is little systematic offset in identified mechanics when sedation is administered.

Matched MeSH terms: Respiratory Mechanics/physiology*
Fulltext Effects of alternate nostril breathing exercise on cardiorespiratory functions in healthy young adults

Jahan I, Begum M, Akhter S, Islam MZ, Jahan N, Samad N, et al.

Ann Afr Med, 2021 7 3;20(2):69-77.
PMID: 34213471 DOI: 10.4103/aam.aam_114_20

Introduction: Alternate nostril breathing (ANB) is an effective breathing exercise with therapeutic benefits on cardiorespiratory functions for healthy and diseased individuals. This study was conducted to assess the effects of ANB exercise on cardiorespiratory tasks in healthy adults.
Materials and Methods: This randomized experimental study was conducted in the Department of Physiology, Chittagong Medical College, Chattogram, from July 2017 to June 2018. A total of 100 1st-year students, aged between 18 and 20 years, were included by a random sampling method. Fifty participants (25 males and 25 females) were enrolled in the experimental group, while age- and body mass index-matched another 50 participants (25 males and 25 females) served as the control group. Experimental group participants performed ANB exercise for 4 weeks. Cardiorespiratory parameters (pulse rate, blood pressure, forced vital capacity, forced expiratory volume in 1st s [FEV1], and peak expiratory flow rate [PEFR] were measured. Data were taken at the start and after 4 weeks in both groups.
Results: Independent t-test showed no significant differences in the cardiorespiratory functions between the experimental and control groups among the male and female participants, except for the females' PEFR which showed small differences. On the other hand, repeated measure ANOVA shows significant improvement in the experimental groups among males (P < 0.001-0.028) and females (P < 0.001-0.001) in all the cardiorespiratory functions measured, except for the FEV1 and PEFR among males.
Conclusion: The results of this study suggest that cardiorespiratory functions were improved after breathing exercise, and therefore, ANB can be recommended for increasing cardiorespiratory efficiency.

Matched MeSH terms: Respiratory Mechanics/physiology*
Respiratory characteristics of individuals with non-specific low back pain: A cross-sectional study

Mohan V, Paungmali A, Sitilerpisan P, Hashim UF, Mazlan MB, Nasuha TN

Nurs Health Sci, 2018 Jun;20(2):224-230.
PMID: 29421851 DOI: 10.1111/nhs.12406

Non-specific low back pain (NS-LBP) is known to cause respiratory dysfunction. In this study, we investigated alterations in breathing, respiratory strength and endurance, core stability, diaphragm mobility, and chest expansion among patients with NS-LBP and healthy individuals. The specific aim of the study was to correlate between respiratory function and other variables among NS-LBP patients. Thirty four patients with NS-LBP were matched with 34 healthy participants before undergoing total faulty breathing scale, spirometer, respiratory pressure meter, chest expansion, ultrasound, and pressure biofeedback measurements. There were signs of faulty breathing in the NS-LBP patients when compared to the healthy participants. Diaphragmatic mobility and respiratory muscle endurance were lower in the NS-LBP group. Chest expansion exhibited a significant decrease at the level of the fourth intercostal space in the NS-LBP group, but respiratory muscle strength and core stability were not significant between the two groups. Positive correlations were found to be fairly significant regarding respiratory muscle strength. The findings of this study indicated altered respiratory characteristics in the NS-LBP patients, and suggested that they would improve through respiratory exercises.

Matched MeSH terms: Respiratory Mechanics/physiology*
Fulltext Stochastic Modelling of Respiratory System Elastance for Mechanically Ventilated Respiratory Failure Patients

Lee JWW, Chiew YS, Wang X, Tan CP, Mat Nor MB, Damanhuri NS, et al.

Ann Biomed Eng, 2021 Dec;49(12):3280-3295.
PMID: 34435276 DOI: 10.1007/s10439-021-02854-4

While lung protective mechanical ventilation (MV) guidelines have been developed to avoid ventilator-induced lung injury (VILI), a one-size-fits-all approach cannot benefit every individual patient. Hence, there is significant need for the ability to provide patient-specific MV settings to ensure safety, and optimise patient care. Model-based approaches enable patient-specific care by identifying time-varying patient-specific parameters, such as respiratory elastance, Ers, to capture inter- and intra-patient variability. However, patient-specific parameters evolve with time, as a function of disease progression and patient condition, making predicting their future values crucial for recommending patient-specific MV settings. This study employs stochastic modelling to predict future Ers values using retrospective patient data to develop and validate a model indicating future intra-patient variability of Ers. Cross validation results show stochastic modelling can predict future elastance ranges with 92.59 and 68.56% of predicted values within the 5-95% and the 25-75% range, respectively. This range can be used to ensure patients receive adequate minute ventilation should elastance rise and minimise the risk of VILI should elastance fall. The results show the potential for model-based protocols using stochastic model prediction of future Ers values to provide safe and patient-specific MV. These results warrant further investigation to validate its clinical utility.

Matched MeSH terms: Respiratory Mechanics/physiology*
Fentanyl dose for the insertion of Classic Laryngeal Mask Airways in non-paralysed patients induced with propofol 2.5 mg/kg

Tan AS, Wang CY

Anaesth Intensive Care, 2010 Jan;38(1):65-9.
PMID: 20191779

The aim of this randomised, controlled trial was to determine the optimum dose of fentanyl in combination with propofol 2.5 mg x kg(-1) when inserting the Classic Laryngeal Mask Airway. Seventy-five ASA I or II patients were randomly assigned to five groups of fentanyl dosage: 0 microg x kg(-1) (placebo), 0.5 microg x kg(-1), 1.0 microg x kg(-1), 1.5 microg x kg(-1) and 2.0 microg x kg(-1). Anaesthesia was induced by first injecting the study drug over 10 seconds. Three minutes after the study drug was injected, propofol (2.5 mg x kg(-1)) was injected over 10 seconds. The Classic Laryngeal Mask Airway was inserted four minutes and 30 seconds after injection of the study drug. Insertion conditions were evaluated using a four-category score. Thirty-nine males and 36 females aged 19 to 59 years were studied. The incidence of prolonged apnoea increased as fentanyl dose increased. We found that there was a high rate of successful first attempt at insertion with 1 microg x kg(-1) and 1.5 microg x kg(-1), 93% and 87% respectively, compared to 87% in the 2.0 microg x kg(-1) group. The 1.0 microg x kg(-1) group also achieved an 80% optimal insertion conditions score of 4, compared to 73% in the 1.5 microg x kg(-1) group and 80% in the 2 microg x kg(-1) group. Therefore we recommend 1.0 microg x kg(-1) as the optimal dose of fentanyl when used in addition to propofol 2.5 mg/kg for the insertion of the Classic Laryngeal Mask Airway.

Matched MeSH terms: Respiratory Mechanics/physiology
Cardiorespiratory findings in epilepsy: A recent review on outcomes and pathophysiology

Akyüz E, Üner AK, Köklü B, Arulsamy A, Shaikh MF

J Neurosci Res, 2021 09;99(9):2059-2073.
PMID: 34109651 DOI: 10.1002/jnr.24861

Epilepsy is a debilitating disorder of uncontrollable recurrent seizures that occurs as a result of imbalances in the brain excitatory and inhibitory neuronal signals, that could stem from a range of functional and structural neuronal impairments. Globally, nearly 70 million people are negatively impacted by epilepsy and its comorbidities. One such comorbidity is the effect epilepsy has on the autonomic nervous system (ANS), which plays a role in the control of blood circulation, respiration and gastrointestinal function. These epilepsy-induced impairments in the circulatory and respiratory systems may contribute toward sudden unexpected death in epilepsy (SUDEP). Although, various hypotheses have been proposed regarding the role of epilepsy on ANS, the linking pathological mechanism still remains unclear. Channelopathies and seizure-induced damages in ANS-control brain structures were some of the causal/pathological candidates of cardiorespiratory comorbidities in epilepsy patients, especially in those who were drug resistant. However, emerging preclinical research suggest that neurotransmitter/receptor dysfunction and synaptic changes in the ANS may also contribute to the epilepsy-related autonomic disorders. Thus, pathological mechanisms of cardiorespiratory dysfunction should be elucidated by considering the modifications in anatomy and physiology of the autonomic system caused by seizures. In this regard, we present a comprehensive review of the current literature, both clinical and preclinical animal studies, on the cardiorespiratory findings in epilepsy and elucidate the possible pathological mechanisms of these findings, in hopes to prevent SUDEP especially in patients who are drug resistant.

Matched MeSH terms: Respiratory Mechanics/physiology*