The Normobaric Oxygen Paradox-Hyperoxic Hypoxic Paradox: A Novel Expedient Strategy in Hematopoiesis Clinical Issues.

Hypoxia, even at non-lethal levels, is one of the most stressful events for all aerobic organisms as it significantly affects a wide spectrum of physiological functions and energy production. Aerobic organisms activate countless molecular responses directed to respond at cellular, tissue, organ, and whole-body levels to cope with oxygen shortage allowing survival, including enhanced neo-angiogenesis and systemic oxygen delivery. The benefits of hypoxia may be evoked without its detrimental consequences by exploiting the so-called normobaric oxygen paradox. The intermittent shift between hyperoxic-normoxic exposure, in addition to being safe and feasible, has been shown to enhance erythropoietin production and raise hemoglobin levels with numerous different potential applications in many fields of therapy as a new strategy for surgical preconditioning aimed at frail patients and prevention of postoperative anemia. This narrative review summarizes the physiological processes behind the proposed normobaric oxygen paradox, focusing on the latest scientific evidence and the potential applications for this strategy. Future possibilities for hyperoxic-normoxic exposure therapy include implementation as a synergistic strategy to improve a patient's pre-surgical condition, a stimulating treatment in critically ill patients, preconditioning of athletes during physical preparation, and, in combination with surgery and conventional chemotherapy, to improve patients' outcomes and quality of life.

Postoperative C-reactive protein kinetics predict postoperative complications in patients treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for peritoneal carcinomatosis.

BACKGROUND: Relatively high morbidity rates are reported after cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). However, early predictors of complications after CRS plus HIPEC have not been identified. The aim of this study was to evaluate the predictive role of early postoperative serum C-reactive protein (CRP) level (Day 2-4) for the detection of post-operative complications. PATIENTS AND METHODS: We performed a retrospective study including 94 patients treated with complete CRS (R1) and HIPEC for PC from various primary origins (2011-2016). Post-operative complications were recorded. The values for postoperative inflammatory markers (white blood cells [WBC] and platelet counts, CRP) were compared between the different groups. RESULTS: CRP on post-operative days 2-4 was significantly higher in patients with than without complications (124 mg/L vs 46 mg/L; p < 0.0001) and higher in those with more major complications (162 mg/L vs 80 mg/L; p < 0.0012). WBC and platelet counts showed no difference within 5 days postoperatively. CONCLUSION: CRP levels, and kinetics mainly, between post-operative day 2 and 4, are decisive predictive markers of early and late post-operative complications after CRS plus HIPEC. The presence of post-operative complications should be suspected in patients with a high CRP mean, and a plateau level (days 2-4).

Exploring the effects of post operative hyperoxic intermittent stimuli on reticulocyte levels in cancer patients: a randomized controlled study.

BACKGROUND: Anemia is common among hospitalized critically ill and surgical oncological patients. The rising incidence of cancer and aggressive treatments has increased the demand for blood products, further strained by a dwindling donor pool. The normobaric oxygen paradox (NOP) has emerged as a potential avenue to increase EPO levels. While some studies support its efficacy, research remains limited in clinical settings. This study aims to assess the effectiveness of a NOP protocol in stimulating erythropoiesis, as measured by changes in reticulocyte counts, in cancer patients undergoing abdominal surgeries. METHODS: This is a post hoc analysis of a prospective, single-center, controlled, randomized study. A total of 49 patients undergoing abdominal surgery were analyzed at the Institut Jules Bordet. Adult patients admitted to the intensive care unit (ICU) for at least 24 h were enrolled, excluding those with severe renal insufficiency or who received transfusions during the study period. Participants were randomized into two groups: a normobaric oxygen paradox (OXY) group who received 60% oxygen for 2 h on days 1, 3, and 5 post-surgery and a control (CTR) group who received standard care. Data on baseline characteristics, surgical details, and laboratory parameters were collected. Statistical analysis included descriptive statistics, chi-square tests, t-tests, Mann-Whitney tests, and linear and logistic regression. RESULTS: The final analysis included 33 patients (median age 62 [IQR 58-66], 28 (84.8%) males, with no withdrawals or deaths during the study period. No significant differences were observed in baseline surgical characteristics or perioperative outcomes between the two groups. In the OXY group (n = 16), there was a significant rise (p = 0.0237) in the percentage of reticulocyte levels in comparison to the CTR group (n = 17), with median values of 36.1% (IQR 20.3-57.8) versus - 5.3% (IQR - 19.2-57.8), respectively. The increases in hemoglobin and hematocrit levels did not significantly differ between the groups when compared to their baselines' values. CONCLUSIONS: This study provides preliminary evidence supporting the potential of normobaric oxygen therapy in stimulating erythropoiesis in cancer patients undergoing abdominal surgeries. While the OXY group resulted in increased reticulocyte counts, further research with larger sample sizes and multi-center trials is warranted to confirm these findings. TRIAL REGISTRATION: The study was retrospectively registered under NCT number 06321874 on The 10th of April 2024.

Perioperative Ketamine and Cancer Recurrence: A Comprehensive Review.

Cancer is a significant global health threat and a leading cause of death worldwide. Effective early-stage interventions, particularly surgery, can potentially cure many solid tumors. However, the risk of postoperative cancer recurrence remains high. Recent research highlights the influence of perioperative anesthetic and analgesic choices on the fate of residual cancer cells, potentially affecting recurrence risks. Among these agents, ketamine-a well-known anesthetic and analgesic-has garnered interest due to its antitumor properties, mainly through inhibiting the N-methyl-D-aspartate (NMDA) receptor found in various cancer tissues. Additionally, ketamine's potential immunomodulatory effects, given the expression of NMDA receptors on immune cells, suggest that it plays a significant role during the perioperative period. This review synthesizes current evidence on ketamine's impact on cancer cell biology, inflammation, immune modulation, and the role of the gut microbiota, proposing ketamine as a promising agent for enhancing oncological outcomes.

Physiological and Clinical Impact of Repeated Inhaled Oxygen Variation on Erythropoietin Levels in Patients After Surgery.

The "Normobaric Oxygen Paradox" (NOP) is a physiologic mechanism that induces an increase of endogenous erythropoietin (EPO) production by creating a state of relative hypoxia in subjects previously exposed to hyperoxia, followed by a rapid return to normoxia. Oxygen exposure duration and inspired oxygen fraction required to observe a significant increase in EPO or hemoglobin are not clearly defined. Consequently, we here study the effect of one model of relative hypoxia on EPO, reticulocytes and hemoglobin stimulation in patients after surgery. Patients were prospectively randomized in two groups. The O2 group (n = 10) received 100% oxygen for 1 h per day for eight consecutive days, via a non-rebreathing mask. The control group (n = 12) received no oxygen variation. Serum EPO, hemoglobin and reticulocyte count were measured on admission and postoperatively on days seven and nine. Percentage EPO at day nine with respect to the baseline value was significantly elevated within the groups [O2 group: 323.7 (SD ± 139.0); control group: 365.6 (SD± 162.0)] but not between them. No significant difference was found between the groups in terms of reticulocytes count and hemoglobin. Our NOP model showed no difference on EPO increase between the two groups. However, both groups expressed separately significant EPO elevation.

Perioperative volume replacement in children undergoing cardiac surgery: albumin versus hydroxyethyl starch 130/0.4.

OBJECTIVE: To compare 4% albumin with 6% hydroxyethyl starch (HES) 130/0.4 in terms of perioperative blood loss and intraoperative fluid requirements in children undergoing cardiac surgery. DESIGN: Prospective randomized study. SETTING: Single University Hospital. PATIENTS: Pediatric patients undergoing cardiac surgery with cardiopulmonary bypass. INTERVENTIONS: One hundred nineteen children were randomized to receive up to 50 mL.kg of either 4% albumin (Alb: n = 59) or 6% HES 130/0.4 (HES: n = 60) for intraoperative fluid volume replacement including the cardiopulmonary bypass priming fluid. Ringer's lactate was used for further intraoperative volume needs. Monitoring, anesthetic, and surgical techniques were standardized. Packed red blood cells were administered according to a strict transfusion protocol. Intra- and postoperative blood loss were measured and also calculated from children's estimated blood volume, pre- and postoperative hematocrit, and volume of transfused packed red blood cells. MEASUREMENTS AND MAIN RESULTS: Volume of colloid used intraoperatively was similar in both groups (median [interquartiles]) (Alb: 50 [45-50] mL x kg; HES: 50 [37-50] mL x kg). Measured and calculated blood loss were not different between groups, but a higher number of children in the albumin group required allogeneic blood transfusion (78% vs. 57%; difference between proportions: 0.213; 95% confidence interval: 0.05-0.38; p = 0.0188). Intraoperative fluid balance was lower in the HES group (Alb 23 [11-39] mL x kg; HES: 12 [-5-30] mL x kg; p = 0.005). Postoperative outcome was not different between groups. CONCLUSIONS: In children undergoing cardiac surgery, 6% HES 130/0.4 may represent an interesting alternative to 4% albumin for intraoperative fluid volume replacement because of its lower cost.