Accessory Muscles of the Lower Calf

COVID-19 pneumonia presents in most patients with significant hypoxemia but without substantial impairment of lung compliance that would increase the work of breathing (WOB) to levels requiring invasive mechanical ventilation. Thus, the ability to assess the WOB independent of the oxygen needs could help guide management and possibly avoid intubation. We previously developed and implemented in our ICU a WOB scale based on respiratory physiology ranging from 1 to 7 by assigning points to the respiratory rate level and the use of respiratory accessory muscles. We analyzed the use of our WOB scale in 10 patients admitted to our ICU with severe COVID-19 pneumonia. All patients had radiographic evidence of extensive lung disease with significant hypoxemia and multiple risk factors associated with poor outcome. Hypoxemia was successfully managed using high-flow nasal cannula. The WOB level was measured every 4 hours. The maximum WOB was 4.3 ± 0.9, contributed primarily by the respiratory rate with a score of 3.6 ± 0.5 but with infrequent use of respiratory accessory muscles. All 10 patients survived without need of intubation. For comparison, three other patients who needed intubation had a maximal work of breathing within the preceding 24 hours of 5.3 ± 1.2 with a respiratory rate score of 3.7 ± 0.6, as in non-intubated patients, but with more often use of respiratory accessory muscles. Our data suggest that patients with COVID-19 pneumonia can be supported for extended periods using HFNC despite tachypnea provided there is only infrequent use of respiratory accessory muscles, corresponding to a WOB scale ≤ 4, prompting closer assessment for possible intubation when WOB > 4. This approach would be especially advantageous under conditions of high disease intensity when avoidance of intubation is likely to result in a better outcome.

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muscle belly, low-lying accessory muscles Accessory Muscles, Low-Lying Muscle Belly

Diagnostic Imaging of the Foot and Ankle ◽

10.1055/b-0034-102499 ◽

2015 ◽

Keyword(s):

Muscle Belly ◽

Accessory Muscles

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Haematemesis

Oxford Cases in Medicine and Surgery ◽

10.1093/oso/9780198716228.003.0011 ◽

2015 ◽

Author(s):

Hugo Farne ◽

Edward Norris-Cervetto ◽

James Warbrick-Smith

Keyword(s):

Head Injury ◽

Central Venous Access ◽

Venous Blood ◽

Venous Access ◽

High Flow ◽

High Flow Oxygen ◽

Do It Yourself ◽

Venous Blood Gas ◽

Accessory Muscles ◽

Intraosseus Access

First of all, call for help. You cannot manage an emergency alone—it involves teamwork. Call for help and involve your seniors. Second, this patient has potentially lost a lot of blood. Start with ABCDE—Airway, Breathing, Circulation, Disability, Exposure. Airway: Ensure it is patent. Can he talk? Is there any gurgling or stridor? Beware of blood in the oropharynx in a patient with haematemesis. If necessary, use suction to remove the blood. Breathing: Are there any signs of respiratory distress (tachypnoea, use of accessory muscles, low saturations)? Circulation: Does he have a pulse? Is he in shock (tachycardia, narrow pulse pressure, hypotension, cold peripheries)? Disability: what is the patient’s Glasgow Coma Score (GCS)? Always calculate this in an emergency as a GCS ≤8 (or rapidly dropping towards that point) suggests that the patient may soon require intubation to protect their airway. If you can’t remember the components of a GCS in an emergency, use the AVPU score (patient is Alert, responds to Voice, responds to Pain or is Unresponsive), where an avPu score (i.e. a patient who is responding to painful stimuli but not voice) is roughly equivalent to a GCS = 8. Exposure: The patient may have suffered multiple trauma and/or have various sites of blood loss. Although it is unlikely, what the hostel staff perceived as drunken behaviour may in fact represent behaviour from an unwitnessed assault resulting in significant head injury, and the haematemesis may reflect a stab wound to the chest or abdomen. Always expose the patient or you will be caught out by unsuspected findings. Mr Tucker is in shock, often defined as a BP <90/60 mmHg. He needs fluid resuscitation: • Apply high flow oxygen (15 L/min). • Get intravenous (IV) access: insert a large-bore (14G–16G) cannula and if you can’t do it yourself, ask a senior to help. They may need to resort to ultrasound-guided peripheral vascular access, to intraosseus access or to central venous access. • Send bloods for: ■ Venous blood gas: this will give you a rapid estimate of the patient’s haemoglobin.

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A perspective of respiratory mechanics

Journal of Applied Physiology ◽

10.1152/jappl.1983.54.5.1183 ◽

1983 ◽

Vol 54 (5) ◽

pp. 1183-1187 ◽

Cited By ~ 19

Author(s):

A. B. Otis

Keyword(s):

Smooth Muscle ◽

Experimental Approach ◽

Respiratory Mechanics ◽

Bronchial Smooth Muscle ◽

Pharmacological Agents ◽

Early 19Th Century ◽

Willem Einthoven ◽

Normal Physiological Function ◽

Accessory Muscles ◽

Muscular Action

Breathing was recognized very early to be a muscular action. The participation of the diaphragm, intercostals, and accessory muscles was appreciated by Galen. Consideration of a possible role for smooth muscle in breathing did not occur until much later. Even today smooth muscle is seldom included as a topic in discussions of “respiratory mechanics.” Bronchial smooth muscle was first described in the classic study of Reisseisen in the early 19th century, although the presence of contractile elements in lungs had been demonstrated a few decades previously. An important comprehensive investigation of the action of bronchial smooth muscle was published in 1892 by Willem Einthoven. His experimental approach became a paradigm. On the other hand, his analysis of dynamic collapse of the airways received little attention and was independently arrived at half a century later. Although we now have a considerable understanding of the mechanics of bronchial smooth muscle and of the effects of numerous physiological and pharmacological agents on its behavior, the exact role it plays in normal physiological function is unclear. Numerous plausible suggestions have been made, but none has been convincingly demonstrated.

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Partitioning of inspiratory pressure swings between diaphragm and intercostal/accessory muscles

Journal of Applied Physiology ◽

10.1152/jappl.1978.44.2.200 ◽

1978 ◽

Vol 44 (2) ◽

pp. 200-208 ◽

Cited By ~ 68

Author(s):

P. T. Macklem ◽

D. Gross ◽

G. A. Grassino ◽

C. Roussos

Keyword(s):

Total Pressure ◽

Pleural Pressure ◽

Inspiratory Pressure ◽

Abdominal Pressure ◽

Abdominal Muscles ◽

Transdiaphragmatic Pressure ◽

Rib Cage ◽

Accessory Muscle ◽

Inspiratory Muscles ◽

Accessory Muscles

We tested the hypothesis that the inspiratory pressure swings across the rib-cage pathway are the sum of transdiaphragmatic pressure (Pdi) and the pressures developed by the intercostal/accessory muscles (Pic). If correct, Pic can only contribute to lowering pleural pressure (Ppl), to the extent that it lowers abdominal pressure (Pab). To test this we measured Pab and Ppl during during Mueller maneuvers in which deltaPab = 0. Because there was no outward displacement of the rib cage, Pic must have contributed to deltaPpl, as did Pdi. Under these conditions the total pressure developed by the inspiratory muscles across the rib-cage pathway was less than Pdi + Pic. Therefore, we rejected the hypothesis. A plot of Pab vs. Ppl during relaxation allows partitioning of the diaphragmatic and intercostal/accessory muscle contributions to inspiratory pressure swings. The analysis indicates that the diaphragm can act both as a fixator, preventing transmission of Ppl to the abdomen and as an agonist. When abdominal muscles remain relaxed it only assumes the latter role to the extent that Pab increases.

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