Extreme Hypoxia Causing Brady-Arrythmias During Apnea in Elite Breath-Hold Divers

Introduction: The cardiac electrical conduction system is very sensitive to hypoglycemia and hypoxia, and the consequence may be brady-arrythmias. Weddell seals endure brady-arrythmias during their dives when desaturating to 3.2 kPa and elite breath-hold-divers (BHD), who share metabolic and cardiovascular adaptions including bradycardia with diving mammals, endure similar desaturation during maximum apnea. We hypothesized that hypoxia causes brady-arrythmias during maximum apnea in elite BHD. Hence, this study aimed to define the arterial blood glucose (Glu), peripheral saturation (SAT), heart rhythm (HR), and mean arterial blood pressure (MAP) of elite BHD during maximum apneas.Methods: HR was monitored with Direct-Current-Pads/ECG-lead-II and MAP and Glu from a radial arterial-catheter in nine BHD performing an immersed and head-down maximal static pool apnea after three warm-up apneas. SAT was monitored with a sensor on the neck of the subjects. On a separate day, a 12-lead-ECG-monitored maximum static apnea was repeated dry (n = 6).Results: During pool apnea of maximum duration (385 ± 70 s), SAT decreased from 99.6 ± 0.5 to 58.5 ± 5.5% (∼PaO2 4.8 ± 1.5 kPa, P < 0.001), while Glu increased from 5.8 ± 0.2 to 6.2 ± 0.2 mmol/l (P = 0.009). MAP increased from 103 ± 4 to 155 ± 6 mm Hg (P < 0.005). HR decreased to 46 ± 10 from 86 ± 14 beats/minute (P < 0.001). HR and MAP were unchanged after 3–4 min of apnea. During dry apnea (378 ± 31 s), HR decreased from 55 ± 4 to 40 ± 3 beats/minute (P = 0.031). Atrioventricular dissociation and junctional rhythm were observed both during pool and dry apneas.Conclusion: Our findings contrast with previous studies concluding that Glu decreases during apnea diving. We conclude during maximum apnea in elite BHD that (1) the diving reflex is maximized after 3–4 min, (2) increasing Glu may indicate lactate metabolism in accordance with our previous results, and (3) extreme hypoxia rather than hypoglycemia causes brady-arrythmias in elite BHD similar to diving mammals.

Effects of the regional nerve blockade at the limb reperfusion in pediatric orthopedics

Introduction. Arterial tourniquets are widely used to improve visualization of the surgical field and to reduce blood loss . However, the resulting ischemia and subsequent reperfusion make doctors seek for better options to reduce these complications. Objective. To find out how the regional nerve blockade impacts the reperfusion of ischemized limb when arterial tourniquets are removed during orthopedic surgeries in children. Material and methods. In 16 patients, who were operated on at the department of trauma and orthopedics of the Novosibirsk Children ‘s Clinical Hospital of Emergency Medical Care (CCHEMC) , surgical intervention required the application of an arterial tourniquet. These patients became participants in an observational pilot study. Patients with tourniquets were divided into two groups: Group I - had the regional nerve blockade ( 9 patients) and Group II - had no regional nerve blockade (7 patients). Parameters of acid-base homeostasis, lactate and arterial blood glucose were assessed in all patients at all stages: before surgery (stage 1), main stage (stage 2), 5 minutes after the tourniquet removal (stage 3). The following parameters were compared in this work: mean arterial pressure (MAP), mm Hg; heart rate (min-1); concentration of lactate in the arterial blood (mmol/l), glycemia (mmol/l). The obtained findings are presented as median (Me) of lower and upper quartiles [Q25; Q75]. Results. The found dynamics of lactate concentration in participants’ blood was the most significant result of the study. In Group I, where regional anesthesia was used, lactate level decreased at the stage 2 and returned to its baseline at the stage 3. In Group II (without regional anesthesia, but with a powerful central analgesic preparation) , lactate level did not change at stage 2, but significantly increased at stage 3. Conclusion. Topical anesthetic (Ropivakaine), used in the regional nerve blockade during orthopedic surgeries in children when arterial tourniquets are put, has less harmful effects in surgical aggression.

Metabolic and Nutritional Characteristics of Long-Stay Critically Ill Patients

Background: insufficient feeding is frequent in the intensive care unit (ICU), which results in poor outcomes. Little is known about the nutrition pattern of patients requiring prolonged ICU stays. The aims of our study are to describe the demographic, metabolic, and nutritional specificities of chronically critically ill (CCI) patients defined by an ICU stay >2 weeks, and to identify an early risk factor. Methods: analysis of consecutive patients prospectively admitted to the CCI program, with the following variables: demographic characteristics, Nutrition Risk Screening (NRS-2002) score, total daily energy from nutritional and non-nutritional sources, protein and glucose intakes, all arterial blood glucose values, length of ICU and hospital stay, and outcome (ICU and 90-day survival). Two phases were considered for the analysis: the first 10 days, and the next 20 days of the ICU stay. Statistics: parametric and non-parametric tests. Results: 150 patients, aged 60 ± 15 years were prospectively included. Median (Q1, Q3) length of ICU stay was 31 (26, 46) days. The mortality was 18% at ICU discharge and 35.3% at 90 days. Non-survivors were older (p = 0.024), tended to have a higher SAPSII score (p = 0.072), with a significantly higher NRS score (p = 0.033). Enteral nutrition predominated, while combined feeding was minimally used. All patients received energy and protein below the ICU’s protocol recommendation. The proportion of days with fasting was 10.8%, being significantly higher in non-survivors (2 versus 3 days; p = 0.038). Higher protein delivery was associated with an increase in prealbumin over time (r2 = 0.19, p = 0.027). Conclusions: High NRS scores may identify patients at highest risk of poor outcome when exposed to underfeeding. Further studies are required to evaluate a nutrition strategy for patients with high NRS, addressing combined parenteral nutrition and protein delivery.