Signe Søvik

In awake older men, self-reporting as healthy but with prevalent well-controlled comorbidities, 15 min of 30° head-down tilt did not affect cerebral blood flow or induce cognitive decline despite significantly increasing noninvasively measured intracranial pressure. Mean arterial pressure at heart level decreased during tilt, ensuring only a marginal increase in mean arterial pressure at ear level. These hemodynamic effects differed considerably from those in anesthetized laparoscopy patients.

We used an innovative approach to modulate the effects of the respiratory pump on circulation in healthy individuals. By synchronizing lower body negative pressure with either inspiration or expiration, the respiratory pump was inhibited or augmented. The arterial blood pressure declined, and its fluctuations became pronounced when the respiratory pump was impeded, and normal cardiorespiratory interactions were disrupted. Cardiorespiratory interactions seem to supersede the strong baroreceptor stimulus generated by cyclic fluctuations in central blood volume.

Swimming in cold water is intrinsically unsafe. One of the threats is a fall in deep-body temperature, which adversely affects all body systems and increases the risk of death. Wetsuits mitigate, but do not negate this threat. Environmental conditions may confound findings from laboratory studies or mathematical models. The study aimed to elucidate associations and patterns of deep-body temperature change in open water wetsuited swimmers, thus facilitating risk assessment and improving swimmer safety. In this exploratory cohort study, following collection of anthropomorphic data including a Dual-energy X-ray Absorptiometry scan, deep-body temperature was continuously measured in 76 open water swims by 31 wetsuited swimmers in water temperatures ranging from 8.4°C to 24.5°C. The temperature trajectories were analyzed by piece-wise and linear mixed model regression. Registered with clinicaltrials.gov NCT06685627. Following immersion, there was a tri-phasic deep-body temperature trajectory, although not all phases were present in all swims: an initial rise, then a plateau phase and then thermal decompensation. Water temperature was correlated with the duration of these phases, as was body habitus for the initial rise. Minimum deep-body temperature was correlated with pre-swim temperature. Despite environmental and individual variations, this paper identified a tri-phasic deep-body temperature trajectory for wetsuited swimmers and proposed physiological mechanisms that may account for them. The tri-phasic pattern of an initial rise, a plateau phase and then thermal decompensation, may be useful in assessing the risks of open water swimming and may facilitate development and validation of deep-body temperature models for wetsuited swimmers.

Purpose: Laboratory studies have demonstrated that manual dexterity decreases with increasing cold, which may adversely affect performance. Dexterity may be impaired by cooling of the hand, cooling of the lower motor neurons, and cognitive impairment. Wetsuits are commonly used in open-water swimming and are mandated in some situations. This study investigates the effects of cold-water wetsuited swimming on dexterity. Methods: Five male and 4 female trained swimmers were recruited for this cohort crossover study. Following dual-energy X-ray absorptiometry scans to determine body composition, they swam in a freshwater lake on 7 occasions with water temperatures between 24.5 °C and 8.4 °C. Dexterity was measured preswim and postswim with a “nut–washer–bolt assembly time test” and cognition with a Stroop test. Core and peripheral body temperatures were continuously monitored. Effects were analyzed by linear mixed-model regression. Results: Pre–post swim difference in time to complete the nut–bolt assembly increased as water temperatures decreased (1.0 s, 95% CI, 0.5–1.5 per 1 °C, P < .0001; R² = .456), to a maximum of 14.7 seconds (95% CI, 3.3–26.0). This represented a 47.5% increase in assembly time from 24.5 °C to 8.4 °C, which we consider to be of practical significance. Decreased dexterity was associated with decreased forearm and scapular temperature and decreased cognitive function. Body composition did not affect dexterity, cognitive function, or body temperature during swims. Water temperature did not affect swim speed. Conclusions: Despite the use of wetsuits, manual dexterity decreased with cold-water swimming. Swimmers, triathletes, and event organizers should consider the implications for safety, performance, and equipment utilization.

Background: In robot-assisted laparoscopic prostatectomy surgery patients are tilted 30°–40° head-down. Knowledge of cerebral autoregulation and determinants of cerebral blood flow in this setting is limited, though postoperative cognitive impairment has been reported. This observational study describes the hemodynamic determinants of cerebral blood flow and dynamics of cerebral perfusion pressure during surgery in the Trendelenburg position and the correlations with postoperative cognition measures.Materials and methods: We included patients scheduled for robot-assisted laparoscopic prostatectomy without known cerebrovascular disease. Cardiac index, mean arterial pressure, central venous pressure, optic nerve sheath diameter as a surrogate for intracranial pressure, ultrasound-measured internal carotid artery (ICA) blood flow and PaCO₂ were recorded at six time points (awake, anesthetized, immediately after tilt, 1 h of tilt, just before end of tilt, and before emerging from anaesthesia). Comprehensive cognitive tests were performed before surgery and 10 and 180 days post-surgery. Data was evaluated using linear regression models.Results: Forty-four males with a mean age of 67 years were included. Duration of anesthesia was 226 min [IQR 201,266] with 165 min [134,199] in head-down tilt. ICA flow decreased after induction of anesthesia (483 vs. 344 ml/min) and remained lowered before increasing at return to horizontal position (331 vs. 407 ml/min). Cerebral perfusion pressure decreased after 1 h tilt (from 73 to 62 mmHg) and remained lowered (66 mmHg) also after return to horizontal position. Optic nerve sheath diameter increased from mean 5.8 mm to 6.4 mm during the course of surgery. ICA flow correlated positively with cardiac index (β 0.367. 1 L/min/m² increase corresponding to 92 ml/min increased ICA flow). PaCO₂ had a positive effect on ICA flow (β 0.145. 1 kPa increase corresponding to 49 ml/min increased ICA flow), while mean arterial pressure had a negative effect (β −0.203. 10 mmHg increase corresponding to a 29 ml/min decline in ICA flow). We found no evidence of postoperative cognitive dysfunction.Conclusion: ICA flow and cerebral perfusion pressure were significantly reduced during robot-assisted laparoscopic prostatectomy surgery. ICA flow positively correlated with cardiac index and PaCO₂, but negatively with mean arterial pressure. Postoperative cognitive function was not impaired.

Large‐volume therapeutic phlebotomy is the mainstay of hemochromatosis treatment and offers an opportunity to investigate the hemodynamic changes during acute hypovolemia. An otherwise healthy 64‐year‐old male with hemochromatosis participated. On nine separate visits, 1000 mL therapeutic phlebotomy was performed. On one occasion, pre‐ and post‐phlebotomy orthostatic challenge with 27° reverse Trendelenburg position was administered. Mean arterial pressure, heart rate, and stroke volume were measured continuously during the procedures. The patient's tolerance to the interventions was continuously evaluated. The procedures were well tolerated by the patient. Mean arterial pressure was maintained during hemorrhage and following phlebotomy in both supine and reverse Trendelenburg positions, primarily through an increase in heart rate and systemic vascular resistance. The present study found that 1000 mL therapeutic phlebotomy in a patient with hemochromatosis may be acceptably and safely used to model hemorrhage. The approach demonstrates high clinical applicability and ethically robustness in comparison with volunteer studies.

Objectives Describe patient transfer patterns within a large Norwegian hospital. Identify risk factors associated with a high number of transfers. Develop methods to monitor intrahospital patient flows to support capacity management and infection control. Design Retrospective observational study of linked clinical data from electronic health records. Setting Tertiary care university hospital in the Greater Oslo Region, Norway. Participants All adult (≥18 years old) admissions to the gastroenterology, gastrointestinal surgery, neurology and orthopaedics departments at Akershus University Hospital, June 2018 to May 2019. Methods Network analysis and graph theory. Poisson regression analysis. Outcome measures Primary outcome was network characteristics at the departmental level. We describe location-to-location transfers using unweighted, undirected networks for a full-year study period. Weekly networks reveal changes in network size, density and key categories of transfers over time. Secondary outcome was transfer trajectories at the individual patient level. We describe the distribution of transfer trajectories in the cohort and associate number of transfers with patient clinical characteristics. Results The cohort comprised 17 198 hospital stays. Network analysis demonstrated marked heterogeneity across departments and throughout the year. The orthopaedics department had the largest transfer network size and density and greatest temporal variation. More transfers occurred during weekdays than weekends. Summer holiday affected transfers of different types (Emergency department-Any location/Bed ward-Bed ward/To-From Technical wards) differently. Over 75% of transferred patients followed one of 20 common intrahospital trajectories, involving one to three transfers. Higher number of intrahospital transfers was associated with emergency admission (transfer rate ratio (RR)=1.827), non-prophylactic antibiotics (RR=1.108), surgical procedure (RR=2.939) and stay in intensive care unit or high-dependency unit (RR=2.098). Additionally, gastrosurgical (RR=1.211), orthopaedic (RR=1.295) and neurological (RR=1.114) patients had higher risk of many transfers than gastroenterology patients (all effects: pConclusions Network and transfer chain analysis applied on patient location data revealed logistic and clinical associations highly relevant for hospital capacity management and infection control.