Gasping
Alan D. Miller, Armand L. Bianchi, Beverly P. Bishop in Neural Control of the Respiratory Muscles, 2019
In many of the studies considered above, gasping has been reversibly produced by exposing animals to anoxia. Once gasping commences, reintroduction of normoxia or hyper-oxia results in a reestablishment of eupnea. To emphasize the clinical importance of gasping, a corollary must be stated: gasping can serve to provide a reoxygenation of the animal and reverse a life-threatening episode. Indeed, “it is thus quite plausible to hypothesize that a failure of autoresuscitation is the final and most devastating physiologic failure in SIDS victims (sudden infant death syndrome).”9
Anatomy of the Respiratory Neural Network
Susmita Chowdhuri, M Safwan Badr, James A Rowley in Control of Breathing during Sleep, 2022
Post-inspiration immediately follows inspiration. It is generally present—and beneficial—during eupnea but not obligatory. Post-inspiration is generally lost in vitro because brainstem-spinal cord preparations retain inspiratory rhythmogenic (preBötC) and expiratory rhythmogenic (pFL) sites. Slice preparations retain only the preBötC. Nevertheless, preparations that include the pons can generate postinspiratory activity measurable via CN IX and CN X (162, 163).
Spinal cord injury and diaphragm neuromotor control
Published in Expert Review of Respiratory Medicine, 2020
Matthew J. Fogarty, Gary C. Sieck
Over the next 5 years, an adequate description of the specific motor unit types afflicted in various spinal cord injury models is necessary, along with a precise description of the specific functional deficits associated with injury. Similarly, the effect of therapies and interventions must be assessed in light of the motor units and type of behavior affected. For too long, the successful intervention has been defined as being a return to the normal pattern and tidal volume generation during eupnea. It is essential that the assessment of non-ventilatory expulsive/straining maneuvers becomes de rigueur in the testing of interventions aimed at improving diaphragm muscle function. For enrollment of patients, eligibility criteria would not be exclusive to those with a cervical injury. Patients could be funneled into pressure-generation assessments based on anecdotal histories (i.e., previous complaints of constipation or weak cough). At first blush, a cross-sectional study would provide some actionable data regarding abdominal pressure generation efforts, to be followed up by longitudinal studies and stratification by age and gender. For preclinical studies, various efforts outlined in this review to classify the effectiveness of intrinsic and circuit (input) substrates for recovery in a size-dependent manner are a reasonable start. We wait with bated breath for a wider adoption of motor unit diversity in the design and characterization of future spinal cord injury research.
Obstructive sleep apnea: personalizing CPAP alternative therapies to individual physiology
Published in Expert Review of Respiratory Medicine, 2022
Brandon Nokes, Jessica Cooper, Michelle Cao
There are several additional metrics traditionally obtained from CPAP dial down techniques which are now routinely modeled from clinical polysomnography in specialized research labs [29,30]. As noted, the ‘passive’ upper airway refers to the behavior of the upper airway in the absence of muscular activity. During CPAP dial down studies, ‘optimum CPAP’ is first obtained and refers to the CPAP level at which the upper airway is unobstructed and ventilatory demands are being adequately met during non-rapid eye movement (NREM) sleep [29]. Over the course of several minutes of unobstructed breathing in NREM sleep, ventilation at eupnea (Veupnea) is established. The CPAP can then be dropped to 0 cmH2O for 3–5 seconds and ventilation through the passive airway (Vpassive) can be obtained [29]. It should be noted that CPAP quiets upper airway dilator activity, and during the first 1–2 breaths of the Vpassive CPAP drop, there is insufficient time for upper airway dilators to activate, thus providing insight into the ‘passive’ behaviors of the upper airway [29]. Notably, while the above techniques are helpful in separating the relative contribution of passive anatomy versus airway dilator activity in airway collapse, accounting for the overlapping role in neural drive perturbations has proven more difficult. For example, recent work from Gell et al., as well as Messineo et al., suggests that many obstructive events, including those in rapid eye movement (REM) sleep, are preceded by a common loss of ventilatory drive (both at the level of genioglossus and the diaphragm) [31,32]. Thus, truly separating the role of the mechanical upper airway from ventilatory drive has proven be quite difficult.
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