The relationship between EMG high frequency and low frequency band amplitude changes correlates with tissue inorganic phosphate levels.

Assessing inorganic phosphate levels seems crucial in deciphering the biochemical state of organisms or tissues. The concentration of inorganic phosphate in blood is an order of magnitude smaller than in tissues and, on top of that, it is dynamically used to fill temporary gaps in tissues. This is the reason blood inorganic phosphate level is considered a poor proxy for tissue levels. Therefore, tissue biopsy seems to be the dominant method when assessing inorganic phosphate levels for instance in muscles. In this study, we attempted to derive a non-invasive biomarker for phosphate tissue levels. We analyzed surface electromyography signals taken during 31P spectroscopy of leg muscles in five adult pigs. We induced hypophosphatemia via 20 minutes-long hyperventilation. It turned out that the proportion of the amplitude of the low frequency band and the high frequency band is significantly (p=0.002) correlated with the relative phosphate levels. The electromyographic signal did not correlate significantly with pCO2 levels in the blood, suggesting that the changes in the signal are a result of inorganic phosphate levels, not hyperventilation. The results might lead to the development of a real-time phosphate fluctuations measurement procedure.

Automatic air volume control system for ventilation of two patients using a single ventilator: a large animal model study.

The COVID-19 pandemic outbreak led to a global ventilator shortage. Hence, various strategies for using a single ventilator to support multiple patients have been considered. A device called Ventil previously validated for independent lung ventilation was used in this study to evaluate its usability for shared ventilation. We performed experiments with a total number of 16 animals. Eight pairs of pigs were ventilated by a ventilator or anesthetic machine and by Ventil for up to 27 h. In one experiment, 200 ml of saline was introduced to one subject's lungs to reduce their compliance. The experiments were analyzed in terms of arterial blood gases and respiratory parameters. In addition to the animal study, we performed a series of laboratory experiments with artificial lungs (ALs). The resistance and compliance of one AL (affected) were altered, while the tidal volume (TV) and peak pressure (Ppeak) in the second (unaffected) AL were analyzed. In addition, to assess the risk of transmission of pathogens between AL respiratory tracts, laboratory tests were performed using phantoms of virus particles. The physiological level of analyzed parameters in ventilated animals was maintained, except for CO2 tension, for which a permissive hypercapnia was indicated. Experiments did not lead to injuries in the animal's lungs except for one subject, as indicated by CT scan analysis. In laboratory experiments, changes in TV and Ppeak in the unaffected AL were less than 11%, except for 2 cases where the TV change was 20%. No cross-contamination was found in simulations of pathogen transmission. We conclude that ventilation using Ventil can be considered safe in patients undergoing deep sedation without spontaneous breathing efforts.

Stress-Induced Phosphaturia in Weaned Piglets.

The weaning period in piglets draws significant attention from researchers, veterinarians, and breeders. A substantial change in diet accompanied by enormous stress has health and welfare implications (abnormal feeding intake, infections, umbilical lesions, etc.). While the parameters like optimal age or weight for the weaning have been studied extensively, relatively less attention has been devoted to the study of stress effects in the piglets' biochemistry. As one of the effects of stress is hyperventilation, a gasometric analysis supported by measurements of hypoxia biomarkers was conducted. Piglets blood and urine, one day and seven days before and one day and seven days after the weaning, were tested. There was no evidence of hyperventilation, but phosphaturia and hypophosphatemia were observed one and seven days postweaning, respectively. A statistical analysis across the population also pointed to minor tissue hypoxia. Our work contributes to an understanding of biochemical dynamics and helps in the interpretation of physiological changes observed in piglets in this critical period.

Which idea is better with regard to immune response? Opioid anesthesia or opioid free anesthesia.

The stress of surgery is characterized by an inflammatory response with immune suppression resulting from many factors, including the type of surgery and the kind of anesthesia, linked with the drugs that are used and the underlying disease of the patient. The trauma of surgery triggers a cascade of reactions involving the immune response and nociception. As strong analgesics, opioids provide the analgesic component of general anesthesia with bi-directional effect on the immune system. Opioids influence almost all aspects of the immune response in regards to leukocytes, macrophages, mast cells, lymphocytes, and NK cells. The suppressive effect of opioids on the immune system is limiting their use, especially in patients with impaired immune response, so the possibility of using multimodal anesthesia without opioids, known as opioid-free anesthesia (OFA), is gaining more and more sympathizers. The idea of OFA is to eliminate opioid analgesia in the treatment of acute pain and to replace it with drugs from other groups that are assumed to have a comparable analgesic effect without affecting the immune system. Here, we present a review on the impact of anesthesia, with and without the use of opioids, on the immune response to surgical stress.

Functional identification of abductor and adductor branches for laryngeal transplantation.

PURPOSE: This is a feasibility study of functional identification of the abductor and adductor recurrent laryngeal nerve branches, which could be used in the donor's larynx for functional laryngeal transplantation. METHODS: The study was performed on swine (n = 3) and human (n = 4) models of a donor larynx. The recurrent laryngeal nerve and its branches were found. Using stimulator, abductor and adductor branches were identified, and glottis closing and opening were captured with an endoscope. RESULTS: The result was positive if two ENT specialists noticed at least one adduction and one abduction movement in the same subject. It was obtained in three out of three swine and three out of four humans. CONCLUSIONS: This study shows a way of reinnervation of a transplanted larynx which might result in a functional organ. It describes the first step of the procedure: functional identification of the abductor and adductor branches of the recurrent laryngeal nerve in the donor before the larynx is excised for transplantation.

Characteristics of bioelectrical activity of oviducts and uterus during early pregnancy in sows recorded by telemetry method.

NEW FINDINGS: What is the central question of this study? The aim of present study was to record and analyse the myoelectrical activity in the female pig reproductive tract (uterus and oviduct) during early pregnancy. What is the main finding and its importance? Understanding the contractile activity of the uterus and oviducts is indispensable for understanding the physiological mechanisms as well as all irregularities associated with the period of conception and early pregnancy. The aim of the present study was to record the myoelectrical activity of the reproductive tract in sows during the oestrous phase and early pregnancy via a telemetry recording system. In a total of eight non-pregnant pigs, the bioelectrical activity was recorded through three silicone electrodes sutured on the oviduct (isthmus and ampulla) and the uterine horn. Blood samples were collected to monitor the concentrations of progesterone (P4) and luteinizing hormone (LH). The oestrous cycle was synchronized with equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG), and the animals were subjected to artificial insemination. Analysis of the EMG activity of the oviduct and uterus in the oestrous phase and in early stages of pregnancy suggests explicitly that telemetry could enable in vivo assessment of myoelectrical activity of parts of the reproductive system in sows. Off-line analysis of the duration of EMG activity bursts in the uterus, isthmus and ampulla were significantly higher during early pregnancy (phases II and III) than in the oestrous phase. The EMG signals demonstrated low mean amplitudes of activity in the oviduct and uterus during early pregnancy (phases I-III). Significant differences between the root mean square signals were observed in the isthmus and ampulla both during oestrus and in early pregnancy (phase I; P < 0.01). During the oestrous phase, the P4 concentration was estimated at <1 ng ml-1 , whereas the LH concentration was >4 ng ml-1 . In contrast, during early pregnancy, the P4 and LH concentrations were estimated at >4 and <1 ng ml-1 , respectively.

Optimum anesthesia for reliable urethral pressure profilometry in female dogs and goats.

OBJECTIVES: To investigate the effects of propofol and isoflurane on urethral pressure profilometry of female dogs and goats, and to identify the method of anesthesia that least influences urethral pressure profilometry and to assess its reproducibility. METHODS: The effects of premedication with midazolam, propofol sedation and isoflurane anesthesia were assessed in five female dogs. The effects of propofol and isoflurane were compared in seven goats, whereas in another group of 19 goats, the state of deep propofol sedation was compared with the state of recovery from propofol sedation. The coefficient of reproducibility and within-subject coefficient of variation were calculated to evaluate test-retest reproducibility. RESULTS: In conscious female dogs, maximal urethral closure pressure and functional area were significantly higher than under propofol or isoflurane (P = 0.04), but not different from the recovery state. In six of seven goats, maximal urethral closure pressure and functional area were higher when measured under propofol sedation than under isoflurane (median maximal urethral closure pressure, 69 vs 47 cmH2 O; P = 0.03). Maximal urethral closure pressure was lower under propofol than during recovery from propofol in 17 of 19 goats (median maximal urethral closure pressure, 54 vs 66 cmH2 O; P < 0.001). The test-retest coefficient of reproducibility for goats was 28 cmH2 O, and the within-subject coefficient of variation was 16%. CONCLUSIONS: In dogs, urethral pressure profilometry should be measured in conscious animals whenever possible. In goats, urethral pressure profilometry is least affected during recovery from propofol sedation, and it shows acceptable reproducibility under this condition.

Substance P and Acute Pain in Patients Undergoing Orthopedic Surgery.

OBJECTIVE: There is a limited information about the role of Substance P (SP) in acute pain nociception following surgical stimulation in patients with a chronic inflammatory state not to mention the link between this neuropeptide level changes and intensity of pain. The goal of the research was to find the correlation between SP level changes and acute pain intensity in patients with rheumatoid arthritis undergoing elective orthopedic surgery. MATERIAL AND METHODS: Patients with rheumatoid arthritis (RA) were enrolled in the study. The correlation between acute pain intensity and concentration of SP in serum as well as in drainage fluid from postoperative wound was assessed in patients with RA who underwent Total Knee Replacement (TKA) under spinal anesthesia. RESULTS: In patients with RA a correlation between intensity of acute pain and serum SP was found postoperatively, whereas there was no correlation between intensity of acute pain and concentration of SP in drainage fluid. CONCLUSIONS: 1. The correlation between acute pain intensity and SP serum concentration was found postoperatively in patients with RA. 2. The correlation between acute pain intensity and SP concentration in drainage fluid was not found postoperatively in patients with RA.

Substance P and Chronic Pain in Patients with Chronic Inflammation of Connective Tissue.

OBJECTIVE: Evidence suggests that substance P (SP) is involved in chronic joint inflammation, such as the pathogenesis of rheumatoid arthritis and osteoarthritis. The goal of the research was to evaluate the correlation between chronic pain and changes in the SP level in patients with chronic inflammation of the connective tissue. METHODS: Patients with osteoarthritis and rheumatoid arthritis were enrolled in this study. The relationship between chronic pain intensity and the serum SP concentration was evaluated in these groups of patients with osteoarthritis and rheumatoid arthritis. RESULTS: The results showed a positive correlation between the serum SP concentrations and chronic pain intensity. CONCLUSIONS: 1. The SP serum concentration was significantly different between the groups of patients with OA and RA. 2. There was a positive correlation between the serum SP concentration and chronic pain intensity in OA and RA patients.