Effects of muscle relaxants on ischaemia damage in skeletal muscle

Molecular mechanisms of muscular and non-muscular actions of neuromuscular blocking agents in critical illness: a narrative review

Despite frequent use of neuromuscular blocking agents in critical illness, changes in neuromuscular transmission with critical illness are not well appreciated. Recent studies have provided greater insights into the molecular mechanisms for beneficial muscular effects and non-muscular anti-inflammatory properties of neuromuscular blocking agents. This narrative review summarises the normal structure and function of the neuromuscular junction and its transformation to a 'denervation-like' state in critical illness, the underlying cause of aberrant neuromuscular blocking agent pharmacology. We also address the important favourable and adverse consequences and molecular bases for these consequences during neuromuscular blocking agent use in critical illness. This review, therefore, provides an enhanced understanding of clinical therapeutic effects and novel pathways for the salutary and aberrant effects of neuromuscular blocking agents when used during acquired pathologic states of critical illness.

Muscle dysfunction in the long coronavirus disease 2019 syndrome: Pathogenesis and clinical approach

In long coronavirus disease 2019 (long COVID‐19), involvement of the musculoskeletal system is characterised by the persistence or appearance of symptoms such as fatigue, muscle weakness, myalgia, and decline in physical and functional performance, even at 4 weeks after the onset of acute symptoms of COVID‐19. Muscle injury biomarkers are altered during the acute phase of the disease. The cellular damage and hyperinflammatory state induced by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection may contribute to the persistence of symptoms, hypoxaemia, mitochondrial damage, and dysregulation of the renin‐angiotensin system. In addition, the occurrence of cerebrovascular diseases, involvement of the peripheral nervous system, and harmful effects of hospitalisation, such as the use of drugs, immobility, and weakness acquired in the intensive care unit, all aggravate muscle damage. Here, we review the multifactorial mechanisms of muscle tissue injury, aggravating conditions, and associated sequelae in long COVID‐19.

Redox-related biomarkers in physical exercise

Research in redox biology of exercise has made considerable advances in the last 70 years. Since the seminal study of George Pake's group calculating the content of free radicals in skeletal muscle in resting conditions in 1954, many discoveries have been made in the field. The first section of this review is devoted to highlight the main research findings and fundamental changes in the exercise redox biology discipline. It includes: i) the first steps in free radical research, ii) the relation between exercise and oxidative damage, iii) the redox regulation of muscle fatigue, iv) the sources of free radicals during muscle contractions, and v) the role of reactive oxygen species as regulators of gene transcription and adaptations in skeletal muscle.

In the second section of the manuscript, we review the available biomarkers for assessing health, performance, recovery during exercise training and overtraining in the sport population. Among the set of biomarkers that could be determined in exercise studies we deepen on the four categories of redox biomarkers: i) oxidants, ii) antioxidants, iii) oxidation products (markers of oxidative damage), and iv) measurements of the redox balance (markers of oxidative stress). The main drawbacks, strengths, weaknesses, and methodological considerations of every biomarker are also discussed.

Protective Effects of Rocuronium Bromide on Ischemia-Reperfusion Injury in Skeletal Muscle Induced by Tourniquet in Patients Undergoing Elective Unilateral Total Knee Arthroplasty: A Prospective, Double Blind, Randomized, Controlled Study

Purpose

To investigate the effects of different doses of rocuronium on ischemia-reperfusion injury in skeletal muscle induced by tourniquet in patients undergoing elective unilateral total knee arthroplasty.

Patients and Methods

A total of 90 patients undergoing elective unilateral knee arthroplasty under general anesthesia combined with femoral nerve block were randomly divided into 3 groups: normal saline group (group S), rocuronium 0.6 mg/kg group (group L), and rocuronium 1.2 mg/kg group (group H). The primary outcome was the expression of dystrophin in skeletal muscle at 60 min after ischemia. Secondary outcomes included the concentration of malondialdehyde (MDA) and neuronal nitric oxide synthase (nNOS) in blood at 5 min and 30 min after reperfusion. In addition, thigh girth at 24 h and 48 h after operation, the leaving bed time, the incidence of tourniquet-related hypertension and short-term (3 days after operation) complications (nausea and vomiting, swelling, blister, wound infection) and long-term (3 months after operation) complications (joint instability, stiffness, nerve paralysis, pain) were recorded.

Main Results

The expression of dystrophin in the rocuronium group was higher than that in group S after ischemia (P <0.05). The concentration of MDA in the rocuronium 1.2 mg/kg group was lower at 30 min after reperfusion (P < 0.05). There was no significant difference in nNOS among groups at each time point (P > 0.05). The change of thigh girth was the smallest in the rocuronium 1.2 mg/kg group after operation (P<0.05). The leaving bed time was significantly earlier after operation in the rocuronium group than that in group S (P <0.05).

Conclusion

Rocuronium can protect skeletal muscle from ischemia-reperfusion injury induced by tourniquet. The mechanism may be related to the fact that rocuronium can reduce the loss of dystrophin in skeletal muscle and have the effects of anti-oxidation and anti-stress.

Trial Registration

The study was registered at http://www.chictr.org.cn (ChiCTR1800019221, registered on 2018-10-31).

Idiopathic Carpal Spasm (Trousseau's Sign) After Intraoperative Arm Tourniquet Inflation in an Intubated Patient

We present a case of a 38-year-old male who sustained a laceration from a knife to the volar aspect of his left index and middle fingers. He had clinical injury to his flexor digitorum profundus tendons to both digits. He underwent operative exploration and repair of the tendons under general anaesthetic. An arm tourniquet was inflated to allow for haemostasis in the operative field. A few minutes after inflation, the patient's hand went into carpal spasm. The tourniquet was deflated and the spasm resolved. Intraoperative serum calcium and carbon dioxide levels were normal. The operation proceeded with the tourniquet deflated. Postoperatively serum calcium and magnesium levels were within normal limits, as was serum vitamin D and parathyroid hormone levels. It has been reported that carpal spasm can occur with tourniquet use in the anxious patient due to hyperventilation and resultant metabolic alkalosis. This however is the first reported case of carpal spasm in the setting of tourniquet use and normal serum electrolytes and respiratory parameters in an intubated patient.

Neuromuscular blockers and reversal agents and their impact on anesthesia practice

Neuromuscular blockers have long been an intricate part of the anesthesia regimen. The scientific progress in pharmacology and physiology has strengthened their clinical relevance, has helped to delineate with precision their medical role, and has enhanced the safety and effectiveness of their use. New frontiers in research will define further the role of these agents in modern anesthesia practice and guide their expanding and discrete clinical applications.