Signe Søvik

• Hyldebrandt, Janus Adler; Nordum, Fredrik Hoff; Tveit, Sjur Hansen; Madsen, Rein Strandli; Idland, Ane-Victoria & Søvik, Signe (2026). Cardiovascular and cognitive consequences of steep head-down tilt in awake older men. Journal of applied physiology. ISSN 8750-7587. 141(3), s. 851–862. doi: 10.1152/japplphysiol.00351.2026. Fulltekst i vitenarkiv
• Skytioti, Maria; Holme, Nathalie; Kousis, Ilias; Søvik, Signe & Elstad, Maja (2026). Impeding respiratory venous return fluctuations alters cardiorespiratory autonomic and mechanical interactions. Journal of applied physiology. ISSN 8750-7587. 140(5), s. 1203–1217. doi: 10.1152/japplphysiol.00113.2025. Fulltekst i vitenarkiv
• Mattingsdal, Håvard; Dahle, Thomas Nordgaard; Abrahamsen, Eirik Bjorheim; Søvik, Signe & Ottestad, William (2025). Workload in helicopter rescue operations – A comparison of two different rescue methods in a randomized cross-over design. Safety Science. ISSN 0925-7535. 192. doi: 10.1016/j.ssci.2025.106996. Fulltekst i vitenarkiv Vis sammendrag

  High workloads can deplete cognitive capacity, impairing individuals’ ability to meet task demands and increasing the likelihood of human error. Helicopter rescue operations are inherently complex and require effective multitasking by all crewmembers. This study aimed to quantify subjective workload and physiological activation associated with two different rescue methods, hoist operations and rope operations, in a three-crew Helicopter Emergency Medical Service. The National Aeronautics and Space Administration (NASA) Task Load Index was used to assess workload. Heart rate and heart rate variability were used as markers for physiological activation. Crews performed fifty-five standardized rescue missions covering four distinct terrain categories: alpine, gorge, forest, and vertical environments. Each mission was solved with both rope and hoist rescue methods, in randomized sequence. Linear mixed-model regression analyses were used to account for repeated measures within individuals. Across all mission phases, pilots (n = 4), physicians (n = 3), and rescuers (n = 4) reported lower workloads during hoist operations than during rope operations. For pilots and rescuers, hoist operations were also associated with lower physiological activation. The opposite was found in physicians, who acted as hoist operators. Rescue method affected pilots most markedly, their mean workload scores during active mission being 35 [19,52] for hoisting versus 53 [37,70] for rope operations (R2 = 0.76, p <0.0001). Analogously, pilot mean heart rate was 80 [57,103] during hoisting compared to 88 [65,111] during rope operations (R2 = 0.91, p <0.0001). A reduction in workload could contribute to improved flight safety, favouring hoist as rescue method.

• Morton, William James; Melau, Jørgen; Olsen, Roar A.; Løvvik, Ole Martin; Hisdal, Jonny & Søvik, Signe (2025). Thermal physiology of open water wetsuited swimming: A cohort study. Temperature. ISSN 2332-8940. 12(3), s. 245–263. doi: 10.1080/23328940.2025.2479893. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Morton, William James; Melau, Jørgen; Olsen, Roar A.; Løvvik, Ole Martin; Hisdal, Jonny & Søvik, Signe (2024). Manual Dexterity in Open-Water Wetsuited Swimmers: A Cohort Crossover Study. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 20(2), s. 213–223. doi: 10.1123/ijspp.2024-0100. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: Laboratory studies have demonstrated that manual dexterity decreases with increasing cold, which may adverselyaffect performance. Dexterity may be impaired by cooling of the hand, cooling of the lower motor neurons, and cognitiveimpairment. Wetsuits are commonly used in open-water swimming and are mandated in some situations. This study investigatesthe effects of cold-water wetsuited swimming on dexterity. Methods: Five male and 4 female trained swimmers were recruited forthis cohort crossover study. Following dual-energy X-ray absorptiometry scans to determine body composition, they swam in afreshwater lake on 7 occasions with water temperatures between 24.5 °C and 8.4 °C. Dexterity was measured preswim andpostswim with a “nut–washer–bolt assembly time test” and cognition with a Stroop test. Core and peripheral body temperatureswere continuously monitored. Effects were analyzed by linear mixed-model regression. Results: Pre–post swim difference intime 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 °Cto 8.4 °C, which we consider to be of practical significance. Decreased dexterity was associated with decreased forearm andscapular temperature and decreased cognitive function. Body composition did not affect dexterity, cognitive function, or bodytemperature during swims. Water temperature did not affect swim speed. Conclusions: Despite the use of wetsuits, manualdexterity decreased with cold-water swimming. Swimmers, triathletes, and event organizers should consider the implications forsafety, performance, and equipment utilization.

• Nordum, Fredrik Hoff; Tveit, Sjur Hansen; Idland, Ane-Victoria; Øyen, Lill Anette; Thomas, Owen Matthew Truscott & Søvik, Signe [Vis alle 7 forfattere av denne artikkelen] (2024). Predictors of cerebral blood flow during surgery in the Trendelenburg position, and their correlations to postoperative cognitive function. Frontiers in Anesthesiology. 3. doi: 10.3389/fanes.2024.1395973. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Søvik, Signe; Barratt-Due, Andreas; Kåsine, Trine; Olasveengen, Theresa M.; Strand, Marianne Wigernes & Tveita, Anders Aune [Vis alle 16 forfattere av denne artikkelen] (2022). Corticosteroids and superinfections in COVID-19 patients on invasive mechanical ventilation. Journal of Infection. ISSN 0163-4453. 85(1), s. 57–63. doi: 10.1016/j.jinf.2022.05.015. Fulltekst i vitenarkiv Vis sammendrag

  Objectives To determine the incidence and characteristics of superinfections in mechanically ventilated COVID-19 patients, and the impact of dexamethasone as standard therapy. Methods This multicentre, observational, retrospective study included patients ≥ 18 years admitted from March 1st 2020 to January 31st 2021 with COVID-19 infection who received mechanical ventilation. Patient characteristics, clinical characteristics, therapy and survival were examined. Results 155/156 patients (115 men, mean age 62 years, range 26-84 years) were included. 67 patients (43%) had 90 superinfections, pneumonia dominated (78%). Superinfections were associated with receiving dexamethasone (66% vs 32%, p<0.0001), autoimmune disease (18% vs 5.7%, p<0.016) and with longer ICU stays (26 vs 17 days, p<0,001). Invasive fungal infections were reported exclusively in dexamethasone-treated patients [8/67 (12%) vs 0/88 (0%), p<0.0001]. Unadjusted 90-day survival did not differ between patients with or without superinfections (64% vs 73%, p=0.25), but was lower in patients receiving dexamethasone versus not (58% vs 78%, p=0.007). In multiple regression analysis, superinfection was associated with dexamethasone use [OR 3.7 (1.80–7.61), p<0.001], pre-existing autoimmune disease [OR 3.82 (1.13–12.9), p=0.031] and length of ICU stay [OR 1.05 p<0.001]. Conclusions In critically ill COVID-19 patients, dexamethasone as standard of care was strongly and independently associated with superinfections.

• Zhang, Chi; Eken, Torsten; Jørgensen, Silje Bakken; Thoresen, Magne & Søvik, Signe (2022). Effects of patient-level risk factors, departmental allocation and seasonality on intrahospital patient transfer patterns: network analysis applied on a Norwegian single-centre data set. BMJ Open. 12(3). doi: 10.1136/bmjopen-2021-054545. Fulltekst i vitenarkiv Vis sammendrag

  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: p<0.001). Conclusions Network and transfer chain analysis applied on patient location data revealed logistic and clinical associations highly relevant for hospital capacity management and infection control.

• Hui, David & Søvik, Signe (2020). Postoperative pain course after paediatric tonsillectomy: A prospective observational study comparing one behavioural and one numerical pain assessment tool. International Journal of Pediatric Otorhinolaryngology. ISSN 0165-5876. 138. doi: 10.1016/j.ijporl.2020.110395. Fulltekst i vitenarkiv Vis sammendrag

  Introduction Paediatric tonsillectomy is often performed as outpatient surgery, although postoperative pain may be severe and protracted. This prospective observational study evaluated two paediatric pain assessment tools for use in telephone interviews with parents. Methods ASA I-II children, ≥1 and < 13 years, undergoing outpatient tonsillectomy were recruited. Anaesthesia (propofol-remifentanil) and intraoperative analgesia were standardized. Sedating premedication was not given. Before discharge, a “smiley face” numerical pain assessment tool was introduced to parents. In telephone interviews on postoperative days 1, 3, 7 and 14, parents scored their childrens pain numerically (0–10) and on the behavioural Postoperative Pain Measure for Parents (PPMP, 0-15). Number of analgesic doses (paracetamol/ibuprofen) per 24 h was noted. Values are median (quartiles). Results 22 consecutive children were included, age 4 (3–6) years. Parents had administered analgesics to 100%, 95%, 80%, and 5% of children at the four interview times. Numerical pain scores were 3.5 (1–7) at hospital discharge, and 5.5 (3–7), 3 (2–6), 3.5 (0–6), and 0 (0-0) on postoperative days 1, 3, 7, and 14, respectively. In 12/22 children, pain declined to a value of 1 (0–2) on day 7. In 6/22 children pain initially declined, but surged to 5.5 (4–7) on day 7. Significant, protracted pain (9 (6–10) on day 7) was reported in 3/22 children. Behavioural (PPMP) scores were positively correlated to numerical pain scores (day 3: R2 = 0.48, day 7: R2 = 0.31, day 14: R2 = 0.85). With increasing age, children systematically had lower behavioural pain scores for the same numerical pain score (0.61 per years age; p < 0.023). Conclusion In structured telephone interviews, parents effectively pain scored their children after outpatient tonsillectomy. Numerical and behavioural pain scores correlated well, however age-dependent. Pain courses varied considerably, and a majority of children had significant pain. Pain after paediatric tonsillectomy should be assessed and treatment individualised.

• Ottestad, William Arne & Søvik, Signe (2020). COVID-19 patients with respiratory failure: what can we learn from aviation medicine? British Journal of Anaesthesia. ISSN 0007-0912. doi: 10.1016/j.bja.2020.04.012. Fulltekst i vitenarkiv
• Omland, Torbjørn; Prebensen, Christian; Røysland, Ragnhild; Søvik, Signe; Sørensen, Vibecke & Røsjø, Helge [Vis alle 9 forfattere av denne artikkelen] (2020). Established Cardiovascular Biomarkers Provide Limited Prognostic Information in Unselected Patients Hospitalized with COVID-19. Circulation. ISSN 0009-7322. 19, s. 1878–1880. doi: 10.1161/CIRCULATIONAHA.120.050089. Fulltekst i vitenarkiv
• Myhre, Peder Langeland; Prebensen, Christian; Strand, Heidi; Røysland, Ragnhild; Jonassen, Christine M. & Rangberg, Anbjørg [Vis alle 12 forfattere av denne artikkelen] (2020). Growth Differentiation Factor-15 Provides Prognostic Information Superior to Established Cardiovascular and Inflammatory Biomarkers in Unselected Patients Hospitalized with COVID-19. Circulation. ISSN 0009-7322. doi: 10.1161/CIRCULATIONAHA.120.050360. Fulltekst i vitenarkiv
• Søvik, Signe; Bådstøløkken, Per Martin; Sørensen, Vibecke; Myhre, Peder Langeland; Prebensen, Christian & Omland, Torbjørn [Vis alle 7 forfattere av denne artikkelen] (2020). A single‐centre, prospective cohort study of COVID‐19 patients admitted to ICU for mechanical ventilatory support. Acta Anaesthesiologica Scandinavica. ISSN 0001-5172. doi: 10.1111/aas.13726. Fulltekst i vitenarkiv Vis sammendrag

  Background Mortality rates in COVID‐19 patients in need of mechanical ventilation are high, with wide variations between countries. Most studies were retrospective, and results may not be generalizable due to differences in demographics, healthcare organization and surge capacity. We present a cohort of mechanically ventilated COVID‐19 patients from a resource‐rich, publicly financed healthcare system. Methods Prospective study from a tertiary hospital. Consecutive SARS‐CoV‐2 positive adult patients admitted to the ICU for mechanical ventilation from 10 March 2020 to 04 May 2020 were included. Triage and treatment were protocolized. High‐dose dalteparin was adjusted by D‐dimer. Demographics, treatments and high‐resolution physiological variables were collected. Outcomes were 30‐day and hospital mortality. Data are medians (quartiles). Results Of the 1484 persons in the hospital catchment area testing positive for SARS‐CoV‐2, 201 (13.5%) were hospitalized. Thirty‐eight (19%) patients were mechanically ventilated, of whom five (13%) died. Of the 163 patients treated with supplemental oxygen, eight (5%) died. In ventilated patients (75% males, age 61 (53‐70) years), severe, moderate and mild ARDS was present in 25%, 70% and 5%. Tidal volume ≤8 mL/kg ideal bodyweight was achieved in 34 (94%) patients. Proning and neuromuscular blockers were used in 19 (54%) and 20 (61%) patients. Duration of ventilation was 12 days (8‐23). D‐dimer peaked at 3.8 mg/L (2.1‐5.3), and maximum dalteparin dose was 15 000 IU/24 h (10 000‐15 000). Despite organizational changes, a high degree of adherence to treatment protocols was achieved. Conclusion In a prospective cohort study of mechanically ventilated COVID‐19 patients treated in a resource‐rich, publicly financed healthcare system, mortality was considerably lower than previously reported in retrospective studies.

• Søvik, Signe; Isachsen, Marie Susanna; Nordhuus, Kine Marie Byman; Tveiten, Christine Kooy; Eken, Torsten & Sunde, Kjetil [Vis alle 8 forfattere av denne artikkelen] (2019). Acute kidney injury in trauma patients admitted to the ICU: a systematic review and meta-analysis. Intensive Care Medicine. ISSN 0342-4642. 45(4), s. 407–419. doi: 10.1007/s00134-019-05535-y. Fulltekst i vitenarkiv Vis sammendrag

  Purpose To perform a systematic review and meta-analysis of acute kidney injury (AKI) in trauma patients admitted to the intensive care unit (ICU). Methods We conducted a systematic literature search of studies on AKI according to RIFLE, AKIN, or KDIGO criteria in trauma patients admitted to the ICU (PROSPERO CRD42017060420). We searched PubMed, Cochrane Database of Systematic Reviews, UpToDate, and NICE through 3 December 2018. Data were collected on incidence of AKI, risk factors, renal replacement therapy (RRT), renal recovery, length of stay (LOS), and mortality. Pooled analyses with random effects models yielded mean differences, OR, and RR, with 95% CI. Results Twenty-four observational studies comprising 25,182 patients were included. Study quality (Newcastle–Ottawa scale) was moderate. Study heterogeneity was substantial. Incidence of post-traumatic AKI in the ICU was 24% (20–29), of which 13% (10–16) mild, 5% (3–7) moderate, and 4% (3–6) severe AKI. Risk factors for AKI were African American descent, high age, chronic hypertension, diabetes mellitus, high Injury Severity Score, abdominal injury, shock, low Glasgow Coma Scale (GCS) score, high APACHE II score, and sepsis. AKI patients had 6.0 (4.0–7.9) days longer ICU LOS and increased risk of death [RR 3.4 (2.1–5.7)] compared to non-AKI patients. In patients with AKI, RRT was used in 10% (6–15). Renal recovery occurred in 96% (78–100) of patients. Conclusions AKI occurred in 24% of trauma patients admitted to the ICU, with an RRT use among these of 10%. Presence of AKI was associated with increased LOS and mortality, but renal recovery in AKI survivors was good.

• Skytioti, Maria; Elstad, Maja & Søvik, Signe (2019). Internal Carotid Artery Blood Flow Response to Anesthesia, Pneumoperitoneum, and Head-up Tilt during Laparoscopic Cholecystectomy. Anesthesiology. ISSN 0003-3022. 131, s. 512–520. doi: 10.1097/ALN.0000000000002838. Fulltekst i vitenarkiv
• Røislien, Jo; Søvik, Signe & Eken, Torsten (2018). Seasonality in trauma admissions - Are daylight and weather variables better predictors than general cyclic effects? PLOS ONE. 13(2). doi: 10.1371/journal.pone.0192568. Fulltekst i vitenarkiv Vis sammendrag

  Trauma is a leading global cause of death, and predicting the burden of trauma admissions is vital for good planning of trauma care. Seasonality in trauma admissions has been found in several studies. Seasonal fluctuations in daylight hours, temperature and weather affect social and cultural practices but also individual neuroendocrine rhythms that may ultimately modify behaviour and potentially predispose to trauma. The aim of the present study was to explore to what extent the observed seasonality in daily trauma admissions could be explained by changes in daylight and weather variables throughout the year.

• Skaga, Nils Oddvar; Eken, Torsten & Søvik, Signe (2018). Validating performance of TRISS, TARN and NORMIT survival prediction models in a Norwegian trauma population. Acta Anaesthesiologica Scandinavica. ISSN 0001-5172. 62(2), s. 253–266. doi: 10.1111/aas.13029. Fulltekst i vitenarkiv Vis sammendrag

  Introduction: Anatomic injury, physiological derangement, age, injury mechanism and pre-injury comorbidity are well-founded predictors of trauma outcome. Statistical prediction models may have poorer discrimination, calibration and accuracy when applied in new locations. We aimed to compare the TRISS, TARN and NORMIT survival prediction models in a Norwegian trauma population. Methods: Consecutive patients admitted to Oslo University Hospital Ullev al within 24 h after injury, with Injury Severity Score ≥ 10, proximal penetrating injuries, or received by trauma team, were studied. Original NORMIT coefficients were updated in a derivation dataset (NORMIT 2; n = 5923; 2005–2009). TRISS, TARN and NORMIT prediction models were evaluated in the validation dataset (n = 6348; 2010–2013) using two different AIS editions for injury coding. Exclusion due to missing data was 0.26%. Outcome was 30-day mortality. Validation included AUROC, scaled Brier statistics, and calibration plots. Results: The NORMIT models had significantly better discrimination, calibration, and overall fit than the TRISS 09, TARN 09 and TARN 12 models. The updated NORMIT 2 had higher numerical values of AUROC and scaled Brier than the original NORMIT, but with overlapping 95%CI. Overlapping 95%CI for AUROCs and Discrimination slopes indicated that the TARN and TRISS models performed similarly. Calibration plots showed tight and consistent predictions over all Ps strata for NORMIT 2 run on AIS’98 coded data, and only little deterioration when AIS’08 data was substituted. Conclusions: In a Norwegian trauma population, the updated Norwegian survival prediction model in trauma (NORMIT 2) performed better than well-established British and US alternatives. External validation of these three models in other Nordic populations is warranted.

• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2018). Dynamic cerebral autoregulation is preserved during isometric handgrip and head-down tilt in healthy volunteers. Physiological Reports. 6(6). doi: 10.14814/phy2.13656. Fulltekst i vitenarkiv Vis sammendrag

  In healthy humans, cerebral blood flow (CBF) is autoregulated against changes in arterial blood pressure. Spontaneous fluctuations in mean arterial pressure (MAP) and CBF can be used to assess cerebral autoregulation. We hypothesized that dynamic cerebral autoregulation is affected by changes in autonomic activity, MAP, and cardiac output (CO) induced by handgrip (HG), head-down tilt (HDT), and their combination. In thirteen healthy volunteers, we recorded blood velocity by ultrasound in the internal carotid artery (ICA), HR, MAP and CO-estimates from continuous finger blood pressure, and endtidal CO2. Instantaneous ICA beat volume (ICABV, mL) and ICA blood flow (ICABF, mL/min) were calculated. Wavelet synchronization index c (0–1) was calculated for the pairs: MAP–ICABF, CO–ICABF and HR–ICABV in the low (0.05–0.15 Hz; LF) and high (0.15–0.4 Hz; HF) frequency bands. ICABF did not change between experimental states. MAP and CO were increased during HG (+16% and +15%, respectively, P < 0.001) and during HDT + HG (+12% and +23%, respectively, P < 0.001). In the LF interval, median c for the MAP–ICABF pair (baseline: 0.23 [0.12–0.28]) and the CO–ICABF pair (baseline: 0.22 [0.15–0.28]) did not change with HG, HDT, or their combination. High c was observed for the HR–ICABV pair at the respiratory frequency, the oscillations in these variables being in inverse phase. The unaltered ICABF and the low synchronization between MAP and ICABF in the LF interval suggest intact dynamic cerebral autoregulation during HG, HDT, and their combination.

• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2018). Respiratory pump maintains cardiac stroke volume during hypovolemia in young, healthy volunteers. Journal of applied physiology. ISSN 8750-7587. 124(5), s. 1319–1325. doi: 10.1152/japplphysiol.01009.2017. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Spontaneous breathing has beneficial effects on the circulation, since negative intrathoracic pressure enhances venous return and increases cardiac stroke volume. We quantified the contribution of the respiratory pump to preserve stroke volume during hypovolemia in awake, young, healthy subjects. Noninvasive stroke volume, cardiac output, heart rate, and mean arterial pressure (Finometer) were recorded in 31 volunteers (19 women), 19–30 yr old, during normovolemia and hypovolemia (approximating 450- to 500-ml reduction in central blood volume) induced by lower-body negative pressure. Control-mode noninvasive positive-pressure ventilation was employed to reduce the effect of the respiratory pump. The ventilator settings were matched to each subject’s spontaneous respiratory pattern. Stroke volume estimates during positive-pressure ventilation and spontaneous breathing were compared with Wilcoxon matched-pairs signed-rank test. Values are overall medians. During normovolemia, positive-pressure ventilation did not affect stroke volume or cardiac output. Hypovolemia resulted in an 18% decrease in stroke volume and a 9% decrease in cardiac output (P < 0.001). Employing positive-pressure ventilation during hypovolemia decreased stroke volume further by 8% (P < 0.001). Overall, hypovolemia and positive-pressure ventilation resulted in a reduction of 26% in stroke volume (P < 0.001) and 13% in cardiac output (P < 0.001) compared with baseline. Compared with the situation with control-mode positive-pressure ventilation, spontaneous breathing attenuated the reduction in stroke volume induced by moderate hypovolemia by 30% (i.e., −26 vs. −18%). In the patient who is critically ill with hypovolemia or uncontrolled hemorrhage, spontaneous breathing may contribute to hemodynamic stability, whereas controlled positive-pressure ventilation may result in circulatory decompensation. NEW & NOTEWORTHY Maintaining spontaneous respiration has beneficial effects on hemodynamic compensation, which is clinically relevant for patients in intensive care. We have quantified the contribution of the respiratory pump to cardiac stroke volume and cardiac output in healthy volunteers during normovolemia and central hypovolemia. The positive hemodynamic effect of the respiratory pump was abolished by noninvasive, low-level positive-pressure ventilation. Compared with control-mode positive-pressure ventilation, spontaneous negative-pressure ventilation attenuated the fall in stroke volume by 30%.

• Wikjord, Kristina Seo; Dahl, Vegard & Søvik, Signe (2017). Effects on nutritional care practice after implementation of a flow chart-based nutrition support protocol in an intensive care unit. Nursing Open. doi: 10.1002/nop2.99. Fulltekst i vitenarkiv Vis sammendrag

  Background: Enteral nutrition (EN) is associated with improved outcome in critically ill patients and is more affordable. We compared nutritional care practice in our ICU before and after modification of our nutrition support protocol: Several comprehensive documents were substituted with one flow chart and early EN was encouraged. Design: Retrospective observational study. Methods: Nutritional data were collected from admission up to 7 days in 25 patients before and 25 patients after protocol modification. Results: The percentage of patients receiving EN within 72 hr of admission increased from 64% before to 88% after protocol modification. Cumulative percentage energy from EN during ICU days 1–4 increased from 26–89% of total kcal. Overall amount of nutrition administered enterally increased, with a corresponding marked decline in use of parenteral nutrition. Pre-modification, >80% of patients received >65% of their calculated nutrition requirements by ICU Day 4; post-modification this goal was achieved by Day 7.

• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2017). Respiration-related cerebral blood flow variability increases during control-mode non-invasive ventilation in normovolemia and hypovolemia. European Journal of Applied Physiology. ISSN 1439-6319. 117(11), s. 2237–2249. doi: 10.1007/s00421-017-3711-0. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: Increased variability in cerebral blood flow (CBF) predisposes to adverse cerebrovascular events. Oscillations in arterial blood pressure and PaCO2 induce CBF variability. Less is known about how heart rate (HR) variability affects CBF. We experimentally reduced respiration-induced HR variability in healthy subjects, hypothesizing that CBF variability would increase. Methods: Internal carotid artery (ICA) blood velocity was recorded by Doppler ultrasound in ten healthy subjects during baseline, control-mode, non-invasive mechanical ventilation (NIV), i.e., with fixed respiratory rate, hypovolemia induced by lower body negative pressure, and combinations of these. ICA beat volume (ICABV) and ICA blood flow (ICABF) were calculated. HR, mean arterial blood pressure (MAP), respiratory frequency (RF), and end-tidal CO2 were recorded. Integrals of power spectra at each subject’s RF ± 0.03 Hz were used to measure variability. Phase angle/coherence measured coupling between cardiovascular variables. Results: Control-mode NIV reduced HR variability (−56%, p = 0.002) and ICABV variability (−64%, p = 0.006) and increased ICABF variability (+140%, p = 0.002) around RF. NIV + hypovolemia reduced variability in HR and ICABV by 70–80% (p = 0.002) and doubled ICABF variability (p = 0.03). MAP variability was unchanged in either condition. Respiration-induced HR and ICABV oscillations were in inverse phase and highly coherent (coherence >0.9) during baseline, but this coherence decreased during NIV, in normovolemia and hypovolemia (p = 0.01). Conclusion: Controlling respiration in awake healthy humans reduced HR variability and increased CBF variability in hypovolemia and normovolemia. We suggest respiration-induced HR variability to be a mechanism in CBF regulation. Maintaining spontaneous respiration in patients receiving ventilatory support may be beneficial also for cerebral circulatory purposes. The final version of this research has been published in European Journal of Applied Physiology. © 2017 Springer Verlag

• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2016). Internal carotid artery blood flow in healthy awake subjects is reduced by simulated hypovolemia and noninvasive mechanical ventilation. Physiological Reports. 4(19). doi: 10.14814/phy2.12969. Fulltekst i vitenarkiv
• Bilben, Bente; Grandal, Linda & Søvik, Signe (2016). National Early Warning Score (NEWS) as an emergency department predictor of disease severity and 90-day survival in the acutely dyspneic patient - a prospective observational study. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. 24:80, s. 1–8. doi: 10.1186/s13049-016-0273-9. Fulltekst i vitenarkiv Vis sammendrag

  Background National Early Warning Score (NEWS) was designed to detect deteriorating patients in hospital wards, specifically those at increased risk of ICU admission, cardiac arrest, or death within 24 h. NEWS is not validated for use in Emergency Departments (ED), but emerging data suggest it may be useful. A criticism of NEWS is that patients with chronic poor oxygenation, e.g. severe chronic obstructive pulmonary disease (COPD), will have elevated NEWS also in the absence of acute deterioration, possibly reducing the predictive power of NEWS in this subgroup. We wanted to prospectively evaluate the usefulness of NEWS in unselected adult patients emergently presenting in a Norwegian ED with respiratory distress as main symptom. Methods In respiratory distressed patients, NEWS was calculated on ED arrival, after 2–4 h, and the next day. Manchester Triage Scale (MTS) category, age, gender, comorbidity (ASA score), ICU-admission, ventilatory support, and discharge diagnoses were noted. Survival status was tracked for >90 days through the Population Registry. Data are medians (25–75th percentiles). Factors predicting 90-day survival were analysed with multiple logistic regression. Results We included 246 patients; 71 years old (60–80), 89 % home-dwelling, 74 % ASA 3–4, 72 % MTS 1–2, 88 % admitted to hospital. NEWS on arrival was 5 (3–7). NEWS correlated closely with MTS category and maximum in-hospital level of care (ED, ward, high-dependency unit, ICU). Sixteen patients died in-hospital, 26 died after discharge within 90 days. Controlled for age, ASA score, and COPD, a higher NEWS on ED arrival predicted poorer 90-day survival. Increased NEWS also correlated with decreased 30-day- and in-hospital survival and a decreased probability for home-dwelling patients to be discharged directly home. Discussion In respiratory distressed patients, NEWS on ED arrival correlated closely with triage category and need of ICU admission and predicted long-term out-of-hospital survival controlled for age, comorbidity, and COPD. Conclusions NEWS should be explored in the ED setting to determine its role in clinical decision-making and in communication along the acute care chain.

• Søvik, Signe; Skaga, Nils Oddvar; Hanoa, Rolf Otto Høe & Eken, Torsten (2014). Sudden survival improvement in critical neurotrauma: An exploratory analysis using a stratified statistical process control technique. Injury. ISSN 0020-1383. 45(11), s. 1722–1730. doi: 10.1016/j.injury.2014.05.038. Fulltekst i vitenarkiv Vis sammendrag

  Background: Outcome after trauma depends on patient characteristics, quality of care, and random events. The TRISS model predicts probability of survival (Ps) adjusted for Injury Severity Score (ISS), Revised Trauma Score (RTS), mechanism of injury, and age. Quality of care is often evaluated by calculating the number of ‘‘excess’’ survivors, year by year. In contrast, the Variable Life-Adjusted Display (VLAD) technique allows rapid detection of altered survival. VLAD adjusts each death or survival by the patient’s risk status and graphically displays accumulated number of unexpected survivors over time. We evaluated outcome changes and their time relation to trauma service improvements. Methods: Observational, retrospective study of the total 2001–2011 trauma population from a Level I trauma centre. Outcome was 30-day survival. Ps was calculated with the TRISS model, 2005 coefficients. VLAD graphs were created for the entire population and for subpopulations stratified by ISS level, ISS body region (Head/Neck, Face, Chest, Abdomen/Pelvic contents, Extremities/Pelvic girdle, External), and maximum Abbreviated Injury Scale (maxAIS) score in each region. Piecewise linear regression identified VLAD graph breakpoints. Results: 12,191 consecutive trauma patients (median age 35 years, 72% males, 91% blunt injury, 41% ISS ! 16) formed the dataset. Their VLAD graph indicated performance equal to TRISS predicted survival until a sudden improvement in late 2004. From then survival remained improved but unchanged through 2011. Total number of excess survivors was 141. Inspection of subgroup VLAD graphs showed that the increased survival mainly occurred in patients having at least one Head/Neck AIS 5 injury. The effect was present in both isolated and multitraumatised maxAIS 5 Head/Neck trauma. The remaining trauma population showed unchanged survival, superior to TRISS predicted, throughout the study period. Important general and neurotrauma-targeted improvements in our trauma service could underlie our findings: A formalised trauma service, damage control resuscitation protocols, structured training, increased helicopter transfer capacity, consultant-based neurosurgical assessment, a doubling of emergency neurosurgical procedures, and improved neurointensive care. Conclusions: Stratified VLAD enables continuous, high-resolution system analysis. We encourage trauma centres to explore their data and to monitor future system changes.

• Staff, Trine; Eken, Torsten; Wik, Lars; Røislien, Jo & Søvik, Signe (2014). Physiologic, demographic and mechanistic factors predicting New Injury Severity Score (NISS) in motor vehicle accident victims. Injury. ISSN 0020-1383. 45(1), s. 9–15. doi: 10.1016/j.injury.2012.11.010. Fulltekst i vitenarkiv
• Jones, J. Mary; Skaga, Nils Oddvar; Søvik, Signe; Lossius, Hans Morten & Eken, Torsten (2014). Norwegian survival prediction model in trauma: Modelling effects of anatomic injury, acute physiology, age, and co-morbidity. Acta Anaesthesiologica Scandinavica. ISSN 0001-5172. 58(3), s. 303–315. doi: 10.1111/aas.12256. Fulltekst i vitenarkiv
• Staff, Trine; Eken, Torsten; Hansen, Trond Boye; Steen, Petter Andreas & Søvik, Signe (2012). A field evaluation of real-life motor vehicle accidents: Presence of unrestrained objects and their association with distribution and severity of patient injuries. Accident Analysis and Prevention. ISSN 0001-4575. 45, s. 529–538. doi: 10.1016/j.aap.2011.09.007. Fulltekst i vitenarkiv
• Staff, Trine & Søvik, Signe (2011). A retrospective quality assessment of pre-hospital emergency medical documentation in motor vehicle accidents in south-eastern Norway. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. 19. doi: 10.1186/1757-7241-19-20. Fulltekst i vitenarkiv
• Skaga, Nils Oddvar; Eken, Torsten; Søvik, Signe; Jones, Mary & Steen, Petter Andreas (2007). Pre-injury ASA physical status classification is an independent predictor of mortality after trauma. Journal of Trauma. ISSN 0022-5282. 63, s. 972–978. Fulltekst i vitenarkiv
• Søvik, Signe & Lossius, Kristin (2004). Development of ventilatory response to transient hypercapnia and hypercapnic hypoxia in term infants. Pediatric Research. ISSN 0031-3998. 55, s. 302–309. Fulltekst i vitenarkiv Vis sammendrag

  Whereas peripheral chemoreceptor oxygen sensitivity increases markedly after birth, previous studies of ventilatory responses to CO(2) in term infants have shown no postnatal development. However, the hypercapnic challenges applied have usually been long-term, which meant that the effect of central chemoreceptors dominated. Oscillatory breathing, apneas, and sighs cause transient Pco(2) changes, probably primarily stimulating peripheral chemoreceptors. We wanted to assess whether the immediate ventilatory responses to step changes in inspired CO(2) and O(2) in term infants undergo postnatal developmental changes. Twenty-six healthy term infants were studied during natural sleep 2 d and 8 wk postnatally. Ventilatory responses to a randomized sequence of 15 s hypercapnia (3% CO(2)), hypoxia (15% O(2)), and hypercapnic hypoxia (3% CO(2) + 15% O(2)) were recorded breath-by-breath using a pneumotachometer. Response rate, stimulus-response time, and response magnitude were analyzed with ANOVA after coherent averaging. Response rate increased with age by 30% (hypercapnia), 318% (hypoxia), and 302% (hypercapnic hypoxia). Response rate during hypercapnic hypoxia exceeded rate during hypercapnia plus rate during hypoxia in wk 8, but not on d 2. Time to half-maximum response decreased by 3.4 s with age for the two hypercapnic stimuli but was unchanged for hypoxia. Response magnitude was unchanged for hypercapnia, but increased for the two hypoxic stimuli. In conclusion, an interaction between the effects of hypercapnia and hypoxia on ventilatory response rate emerged between postnatal d 2 and wk 8 in term infants. Concomitantly, stimulus-response time to hypercapnic stimuli declined markedly. The development of a prompt response to transient hypercapnia may be important for infant respiratory stability

• Eggesbø, Heidi Beate; Søvik, Signe; Dølvik, Sverre; Eiklid, Kristin Louise & Kolmannskog, Finn (2003). Proposal of a CT scoring system of the paranasal sinuses in diagnosing cystic fibrosis. European Radiology. ISSN 0938-7994. 13(6), s. 1451–1460. doi: 10.1007/s00330-003-1825-8. Fulltekst i vitenarkiv
• Eggesbø, Heidi Beate; Søvik, Signe; Dølvik, Sverre & Kolmannskog, Finn (2002). CT characterization of inflammatory paranasal sinus disease in cystic fibrosis. Acta Radiologica. ISSN 0284-1851. 43(1), s. 21–28. Fulltekst i vitenarkiv

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• Mattingsdal, Håvard; Dahle, Thomas Nordgaard; Søvik, Signe & Ottestad, William (2024). NASA Task Load Index assessment of workload during human external cargo operations in norwegian helicopter emergency medical services. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. 32(S1), s. 1–1. doi: 10.1186/s13049-024-01278-y. Fulltekst i vitenarkiv Vis sammendrag

  Background Human error is a common cause in flight operation accidents. Human External Cargo operations (HEC) are complex and demand effective multi-tasking from all operators. A high workload can deplete cognitive capacity, compromising the ability to meet task demands and increasing the probability of human error [1, 2]. The Norwegian Air Ambulance Foundation is investigating the feasibility of transitioning from static Rope Rescue Operations (RRO) to Helicopter Hoist Operations (HHO). We aimed to quantify workload during rescue operations in a three-crew helicopter operation. Method Study crews proficient in both methods solved multiple standardised rescue missions. Missions were divided into three phases; reconnaissance, rescuer insertion- and extraction. Overall workload was registered with the NASA Task Load Index (NASA-TLX) [3]. The study included four experienced pilots, three hoist operators and three rescuers. HEC method sequence and rescue missions were randomised. All crews solved each mission with both methods. To account for repeated measures within individuals, linear mixed-model regression analyses were performed in JMP 17.0.0 (SAS Institute, Cary, NC). P values 

• Morton, William James; Hauge, Anton; Opdahl, Helge; Rein, Erling Bekkestad; Søvik, Signe & Hisdal, Jonny (2024). Nine treatments of 1000 mL therapeutic phlebotomy in a subject with polycythemia: A case report. Physiological Reports. 12(11), s. 1–5. doi: 10.14814/phy2.16035. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Holme, Nathalie Linn Anikken; Skytioti, Maria; Søvik, Signe & Elstad, Maja (2020). Induced respiratory variability in arterial blood pressure lowers cerebral blood flow in healthy humans. Fulltekst i vitenarkiv Vis sammendrag

  In this study we examined the effect of respiratory oscillations in arterial blood pressure and cardiac output, induced by oscillatory lower body negative pressure, on cerebral blood flow in healthy humans. We found that respiratory oscillations in arterial blood pressure and cardiac output lowered the median cerebral blood flow. In addition, as oscillations in cerebral blood flow increased during oscillatory lower body negative pressure, we conclude that respiratory oscillations in arterial blood pressure and cardiac output are transferred to the cerebral circulation. Induced respiratory oscillations in arterial blood pressure and in flow therefore lower cerebral blood flow in healthy humans.

• Haines, Ryan W.; Harrois, Anatole; Prowle, John R.; Søvik, Signe & Beitland, Sigrid (2019). Deserved attention for acute kidney injury after major trauma. Intensive Care Medicine. ISSN 0342-4642. 45(6), s. 907–908. doi: 10.1007/s00134-019-05609-x. Fulltekst i vitenarkiv
• Skytioti, Maria; Elstad, Maja & Søvik, Signe (2019). Blodflow i arteria carotis interna faller parallelt med cardiac index under laparoskopisk cholecystectomi, uavhengig av blodtrykket. Fulltekst i vitenarkiv
• Holme, Nathalie Linn Anikken; Lehre, Martin Andreas; Søvik, Signe; Skytioti, Maria & Elstad, Maja (2019). Cerebral Autoregulation Fails to Maintain Cerebral Blood Flow During Arterial Blood Pressure Oscillations at Respiratory Frequency. Fulltekst i vitenarkiv
• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2018). Differential response of internal carotid artery blood flow to cardiac output changes. Fulltekst i vitenarkiv
• Søvik, Signe; Isachsen, Marie Susanna; Nordhuus, Kine Marie Byman; Tveiten, Christine Kooy; Eken, Torsten & Sunde, Kjetil [Vis alle 8 forfattere av denne artikkelen] (2018). Acute kidney injury in trauma patients admitted to the intensive care unit: a systematic review and meta-analysis. Intensive Care Medicine Experimental. 6, s. 474–474. doi: 10.1186/s40635-018-0201-6. Fulltekst i vitenarkiv
• Holme, Nathalie Linn Anikken; Lehre, Martin Andreas; Søvik, Signe; Elstad, Maja & Skytioti, Maria (2018). Responses in cardiac stroke volume index and cardiac index do not differ between genders during moderate central hypovolemia. Fulltekst i vitenarkiv
• Hui, David & Søvik, Signe (2018). Postoperativt smerteforløp etter dagkirurgisk tonsillektomi hos barn, vurdert gjennom telefonintervju av foreldre. Fulltekst i vitenarkiv
• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2017). Den respiratoriske sirkulasjonspumpen opprettholder hjertets slagvolum ved hypovolemi hos friske individer. Fulltekst i vitenarkiv
• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2017). Internal carotid artery blood flow response to isometric handgrip and head down tilt in healthy volunteers. Fulltekst i vitenarkiv
• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2016). Respiratory sinus arrhythmia buffers variability in cerebral blood flow. Fulltekst i vitenarkiv
• Skytioti, Maria; Søvik, Signe & Elstad, Maja (2015). CEREBRAL BLOOD FLOW CHANGES IN RESPONSE TO MILD HYPOVOLEMIA AND POSITIVE PRESSURE VENTILATION. Fulltekst i vitenarkiv
• Stensby, Ellen Kristine; Søvik, Signe; Loewhagen, Bjørn & Dahl, Vegard (2013). The successful reversal of a fulminant anaphyactic reaction to rocuronium with suggammadex in an 11 year old boy: A case report. Acta Anaesthesiologica Scandinavica. ISSN 0001-5172. 57, s. 15–15. Fulltekst i vitenarkiv

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