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Mechanics of Cycling
Published in Christopher L. Vaughan, Biomechanics of Sport, 2020
Dirk J. Pons, Christopher L. Vaughan
A study by Smith et al.50 showed that an arm crank is a less strenuous method of locomotion than handrim propulsion of wheelchairs. They based this conclusion on measurements of oxygen consumption, ventilation rate, and heart rate. Various hand-cranked wheelchairs have been developed and these may be superior to handrim propulsion. Electrical stimulation of paralyzed leg muscles to power a wheelchair has also been investigated,51–53 and this technology holds potential for the rehabilitation of paraplegics.
Diagnosis of exercise-induced bronchoconstriction
Published in John W. Dickinson, James H. Hull, Complete Guide to Respiratory Care in Athletes, 2020
Oliver J. Price, John W. Dickinson, John D. Brannan
For those with established clinical asthma frequently require β2-agonists to alleviate respiratory symptoms, the EVH test should be performed with caution knowing that the airway stimulus is highly potent and therefore may induce significant bronchospasm in susceptible individuals. Thus, safety precautions should be implemented during an EVH test and should only be performed by trained specialists familiar with the procedure (e.g. respiratory physiologist or technician). The EVH test should not be performed on athletes in whom baseline FEV1 is less than 75% of predicted. BHR may occur during ventilation and any sudden falls in ventilation rate could be an indication of bronchoconstriction. In this scenario, the test may need to be terminated and FEV1 measured immediately, followed by the administration of a rescue bronchodilator (i.e. 4 × 100ug salbutamol via pressurised metered dose inhaler and spacer).
Drugs to keep you asleep: the inhalational agents
Published in Daniel Cottle, Shondipon Laha, Peter Nightingale, Anaesthetics for Junior Doctors and Allied Professionals, 2018
This can be achieved by using a high alveolar ventilation rate, a high inspired concentration of the agent or by utilising the second gas effect (explained shortly). High alveoli concentrations allow rapid equilibrium with the blood and a quicker onset of anaesthesia.
Prehospital Manual Ventilation: An NAEMSP Position Statement and Resource Document
Published in Prehospital Emergency Care, 2022
John W. Lyng, Francis X. Guyette, Michael Levy, Nichole Bosson
Both BVM and BVD strategies of manual ventilation require the EMS clinician to deliver manual ventilation at the appropriate rate and volume for the patient’s clinical condition. Distractions in the prehospital environment can draw an EMS clinician’s attention away from providing high-quality manual ventilation, leading to inadvertent hyperventilation. Both over-ventilation and insufficient ventilation can be detrimental to patient outcomes (51). The AHA guidelines recommend an adult ventilation rate of 10 breaths per minute with tidal volumes of 500–600 mL, and a pediatric rate of 20–30 breaths per minute (with no pediatric-specific tidal volume recommendation), while also specifically highlighting the need to avoid excessive ventilation (52). Other sources recommend pediatric tidal volume of 6–7 ml/kg, though it is likely difficult to deliver this specifically calculated volume using a bag-valve device (53). Unfortunately using chest-rise is not an effective method to assess delivery of adequate tidal volume during manual ventilation of pediatric patients (54).
Optimizing Physiology During Prehospital Airway Management: An NAEMSP Position Statement and Resource Document
Published in Prehospital Emergency Care, 2022
Daniel P. Davis, Nichole Bosson, Francis X. Guyette, Allen Wolfe, Bentley J. Bobrow, David Olvera, Robert G. Walker, Michael Levy
Several components of airway management may compromise perfusion. Positive-pressure ventilation may create or exacerbate hypotension and may contribute to tension physiology with pneumothorax. In addition, medications used to facilitate airway management during DAAM may have cardiovascular side effects, such as negative inotropy, bradycardia, or vasodilation. These effects may be mitigated by the use of volume or vasopressor infusion, reversal of obstructive shock (decompression), or the use of push dose vasopressors prior to induction, during, or after the procedure. Hypotension should be reversed prior to advanced airway management to reduce or limit complications related to hypoperfusion (25–28). In addition, modification of ventilation strategies, such as a reduction in ventilation rate, tidal volume/inspiratory pressure, or inspiratory time, may reduce negative effects on perfusion.
Particle and inhalation exposure in human and monkey computational airway models
Published in Inhalation Toxicology, 2018
Nguyen Lu Phuong, Nguyen Dang Khoa, Kiao Inthavong, Kazuhide Ito
To simulate the airflow pattern and particle deposition in the human and monkey models, the inspiratory flow rates are needed. According to Fanger (1970), under normal circumstances, the pulmonary ventilation rate is primarily known as a function of the metabolic rate and a proportionality constant. We then selected the representative breathing airflow rate corresponding to the metabolic rate. The type of airflow regime (from laminar–turbulent flow) is also difficult to define due to the complexity of the airway structures. The numerical simulations of realistic human nasal airways reveal a laminar flow regime for flow rates less than 20 L/min (Garcia et al., 2007; Naftali et al., 2005; Schroeter et al., 2008). Kelly et al. (2000) have reported that the laminar flow regime dominates for flow rates around 10 L/min. In this study, steady flow rates of 10, 20 and 30 L/min were used with a prescribed laminar–turbulent flow regime for the human airway. Steady inhalation flow rates of 2.2, 4.6 and 6.9 L/min were applied for the monkey model as representative flow regimes that are similar to the human airway. Further, these flow rates were considered a function of metabolic rate (e.g. light [rest], moderate and intense activity) in accordance with the experimental condition reported by Kelly et al. (2005). The walls of the airway and the turbinate are assumed to be rigid structures. The fluid conditions were specified at the trachea opening, with the velocity perpendicular to the cross-section of the trachea opening and defined using a constant magnitude.