Lars Øivind Høiseth

• Lie, Sole Lindvåg; Hisdal, Jonny; Rehn, Marius & Høiseth, Lars Øivind (2024). Effect of systemic vascular resistance on the agreement between stroke volume by noninvasive pulse wave analysis and Doppler ultrasound in healthy volunteers. PLOS ONE. ISSN 1932-6203. 19(5). doi: 10.1371/journal.pone.0302159.
• Lie, Sole Lindvåg; Hisdal, Jonny; Rehn, Marius & Høiseth, Lars Øivind (2023). Hemodynamic effects of supplemental oxygen versus air in simulated blood loss in healthy volunteers: a randomized, controlled, double-blind, crossover trial. Intensive Care Medicine Experimental. ISSN 2197-425X. 11(1). doi: 10.1186/s40635-023-00561-z. Full text in Research Archive
• Nesaragi, Naimahmed; Høiseth, Lars Øivind; Qadir, Hemin Ali; Rosseland, Leiv Arne; Halvorsen, Per Steinar & Balasingham, Ilangko (2023). Non-invasive waveform analysis for emergency triage via simulated hemorrhage: An experimental study using novel dynamic lower body negative pressure model. Biocybernetics and Biomedical Engineering (BBE). ISSN 0208-5216. 43(3), p. 551–567. doi: 10.1016/j.bbe.2023.06.002. Full text in Research Archive
• Høiseth, Lars Øivind; Fjose, Lars Olav; Hisdal, Jonny; Comelon, Marlin; Rosseland, Leiv Arne & Lenz, Harald (2023). Haemodynamic effects of methoxyflurane versus fentanyl and placebo in hypovolaemia: a randomised, double-blind crossover study in healthy volunteers. BJA Open. ISSN 2772-6096. 7. doi: 10.1016/j.bjao.2023.100204. Full text in Research Archive
• Djupedal, Håvard; Nøstdal, Torkjell; Hisdal, Jonny; Landsverk, Svein A. & Høiseth, Lars Øivind (2022). Effects of experimental hypovolemia and pain on pre-ejection period and pulse transit time in healthy volunteers. Physiological Reports. ISSN 2051-817X. 10(12), p. 1–10. doi: 10.14814/phy2.15355. Full text in Research Archive Show summary

  Trauma patients may suffer significant blood loss, and noninvasive methods to diagnose hypovolemia in these patients are needed. Physiologic effects of hypovolemia, aiming to maintain blood pressure, are largely mediated by increased sympathetic nervous activity. Trauma patients may however experience pain, which also increases sympathetic nervous activity, potentially confounding measures of hypovolemia. Elucidating the common and separate effects of the two stimuli on diagnostic methods is therefore important. Lower body negative pressure (LBNP) and cold pressor test (CPT) are experimental models of central hypovolemia and pain, respectively. In the present analysis, we explored the effects of LBNP and CPT on pre-ejection period and pulse transit time, aiming to further elucidate the potential use of these variables in diagnosing hypovolemia in trauma patients. We exposed healthy volunteers to four experimental sequences with hypovolemia (LBNP 60 mmHg) or normovolemia (LBNP 0 mmHg) and pain (CPT) or no pain (sham) in a 2 × 2 fashion. We calculated pre-ejection period and pulse transit time from ECG and ascending aortic blood velocity (suprasternal Doppler) and continuous noninvasive arterial pressure waveform (volume-clamp method). Fourteen subjects were available for the current analyses. This experimental study found that pre-ejection period increased with hypovolemia and remained unaltered with pain. Pulse transit time was reduced by pain and increased with hypovolemia. Thus, the direction of change in pulse transit time has the potential to distinguish hypovolemia and pain.

• Pradhan, Gaurav N.; Ottestad, William Arne; Meland, Anders; Kåsin, Jan Ivar; Høiseth, Lars Øivind & Cevette, Michael J. [Show all 7 contributors for this article] (2021). Oculometric Feature Changes During Acute Hypoxia in a Simulated High-Altitude Airdrop Scenario. Aerospace Medicine and Human Performance. ISSN 2375-6314. 92(12), p. 928–936. doi: 10.3357/AMHP.5930.2021. Full text in Research Archive Show summary

  BACKGROUND: Severe acute hypoxia results in a rapid deterioration of cognitive functioning and thus poses a risk for human operations in high altitude environments. This study aimed at investigating the effects of oxygen system failure during a high-altitude high-opening (HAHO) parachute jump scenario from 30,000 ft (9144 m) on human physiology and cognitive performance using a noncontact eye-tracking task. METHODS: Nine healthy male volunteers (ages 27–48) were recruited from the Norwegian Special Operations Commandos. Eye-tracking data were collected to derive information on cognitive performance in the context of rapid dynamic changes in pressure altitude while performing a modified King-Devick test. The baseline data was collected at 8000 ft (2438 m) while breathing 100% oxygen during decompression. For every test, the corresponding arterial blood gas analysis was performed. RESULTS: The study subjects endured severe hypoxia, which resulted in significant prolongations of fixation time (range: 284.1–245.6 ms) until 23,397 ft (131 m) and fixation size (range: 34.6–32.4 mm) until 25,389 ft (7739 m) as compared to the baseline (217.6 ± 17.8 ms and 27.2 ± 4.5 mm, respectively). The increase in the saccadic movement and decrease in the saccadic velocity was observed until 28,998 ft and 27,360 ft (8839 and 8339 m), respectively. DISCUSSION: This is the first study to investigate cognitive performance from measured oculometric variables during severe hypobaric hypoxia in a simulated high-altitude airdrop mission scenario. The measurement of altered oculometric variables under hypoxic conditions represents a potential avenue to study altered cognitive performance using noncontact sensors that can derive information and serve to provide the individual with a warning from impending incapacitation.

• Hoel, Henrik; Pettersen, Erik Mulder; Høiseth, Lars Øivind; Mathiesen, Iacob; Seternes, Arne & Hisdal, Jonny (2021). Lower Extremity Intermittent Negative Pressure for Intermittent Claudication. Follow-Up after 24 Weeks of Treatment. Annals of Vascular Surgery. ISSN 0890-5096. 75, p. 253–258. doi: 10.1016/j.avsg.2021.03.016. Full text in Research Archive Show summary

  Background Treatment with lower extremity intermittent negative pressure (INP) of -40 mm Hg for one hour twice daily for 12 weeks, increases walking capacity in patients with intermittent claudication (IC). However, the effects of INP treatment beyond 12 weeks have not been elucidated. The aim of the present study was to investigate the clinical effects of INP treatment after 24 weeks in patients with IC. Methods This was a follow-up study after a randomized sham-controlled trial, where patients randomized to the active treatment group were offered to continue treatment for 12 additional weeks (24 weeks in total). Treatment with -40 mm Hg INP was applied in a pressure chamber sealed around the lower leg, and the patients were instructed to treat themselves at home one hour in the morning and one hour in the evening. Pain free walking distance (PWD), maximal walking distance (MWD), resting ankle-brachial index (ABI) and post exercise ABI were measured at baseline, after 12 and 24 weeks. Results Ten out of 32 patients (31%) from the active treatment group in the initial trial were included in this follow-up study. At baseline, PWD was (mean ±SD) 151 ± 91 m and MWD was 362 ±159 m. There was a significant increase in both PWD and MWD after 24 weeks of treatment, compared to baseline (ANOVA; P= 0.006 and P= 0.012, respectively). Post hoc tests revealed that PWD increased significantly from baseline to 12 weeks (mean 81 m; 95% CI [6, 156]; P = 0.032), and that MWD increased significantly from 12 to 24 weeks (mean 145 m; 95% CI [22, 268]; P = 0.018). There were no significant changes in resting ABI or post exercise ABI during the 24-week treatment period (ANOVA; P= 0.157 and P= 0.450, respectively). Conclusion Both PWD and MWD improved after treatment with – 40 mm Hg INP for one hour twice daily for 24 weeks, compared to baseline. The main improvement in PWD occurred during the first 12 weeks of treatment, whereas the main improvement in MWD occurred between 12 and 24 weeks of treatment.

• Lie, Sole Lindvåg; Hisdal, Jonny & Høiseth, Lars Øivind (2021). Cerebral blood flow velocity during simultaneous changes in mean arterial pressure and cardiac output in healthy volunteers. European Journal of Applied Physiology. ISSN 1439-6319. p. 1–11. doi: 10.1007/s00421-021-04693-6. Full text in Research Archive
• Høiseth, Lars Øivind; Melau, Jørgen; Bonnevie-Svendsen, Martin; Nyborg, Christoffer; Eijsvogels, Thijs M. H. & Hisdal, Jonny (2021). Core temperature during cold-water triathlon swimming. Sports. ISSN 2075-4663. 9(6), p. 1–7. doi: 10.3390/sports9060087. Full text in Research Archive Show summary

  Triathlon and other endurance races have grown in popularity. Although participants are generally fit and presumably healthy, there is measurable morbidity and mortality associated with participation. In triathlon, most deaths occur during the swim leg, and more insight into risk factors, such as hypothermia, is warranted. In this study, we measured the core temperature of 51 participants who ingested temperature sensor capsules before the swim leg of a full-distance triathlon. The water temperature was 14.4–16.4 °C, and the subjects wore wetsuits. One subject with a low body mass index and a long swim time experienced hypothermia (<35 °C). Among the remaining subjects, we found no association between core temperature and swim time, body mass index, or sex. To conclude, the present study indicates that during the swim leg of a full-distance triathlon in water temperatures ≈ 15–16 °C, subjects with a low body mass index and long swim times may be at risk of hypothermia even when wearing wetsuits.

• Hoel, Henrik; Pettersen, Erik Mulder; Høiseth, Lars Øivind; Mathiesen, Iacob; Seternes, Arne & Seljeflot, Ingebjørg [Show all 7 contributors for this article] (2021). Effects of intermittent negative pressure treatment on circulating vascular biomarkers in patients with intermittent claudication. Vascular Medicine. ISSN 1358-863X. 26(5), p. 489–496. doi: 10.1177/1358863X211007933. Full text in Research Archive Show summary

  The aim of this study was to investigate the effects of lower extremity intermittent negative pressure (INP) treatment for 1 hour twice daily for 12 weeks, on circulating vascular biomarkers in patients with intermittent claudication. Patients were randomized to treatment with –40 mmHg INP (treatment group), or –10 mmHg INP (sham control group). Venous blood samples were collected at baseline and after 12 weeks, and concentrations of vascular adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), E-selectin, P-selectin, von Willebrand factor (vWF), l-arginine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) were analyzed. A larger proportion of the patients in the treatment group (25/31) had a reduction in vWF levels after 12 weeks, compared to the sham control group (17/30) (p = 0.043). Within the treatment group there was a significant mean (SEM) reduction in the concentration of vWF of –11% (4) (p = 0.019), whereas there was no significant change in the levels of vWF in the sham control group (1% (6); p = 0.85). There were no significant differences in the change of any of the biomarker levels between the groups after 12 weeks of treatment. In conclusion, there were no differences in the change of the circulating levels of the measured biomarkers between the treatment group and the sham control group after 12 weeks of INP treatment. However, the observed changes in vWF might indicate a beneficial effect of INP treatment on endothelial activation and endothelial injury. Clinicaltrials.gov Identifier: NCT03640676

• Hoel, Henrik; Pettersen, Erik Mulder; Høiseth, Lars Øivind; Mathiesen, Iacob; Seternes, Arne & Hisdal, Jonny (2021). A randomized controlled trial of treatment with intermittent negative pressure for intermittent claudication. Journal of Vascular Surgery. ISSN 0741-5214. 73(5), p. 1750–1758.e1. doi: 10.1016/j.jvs.2020.10.024. Show summary

  Objective: We investigated the effects of lower extremity intermittent negative pressure (INP) treatment for 1 hour two times daily for 12 weeks on the walking distance of patients with intermittent claudication (IC). Methods: Patients with IC were randomized to treatment with 40 mm Hg INP (treatment group) or 10 mm Hg INP (sham control group). Pain-free walking distance (PWD) and maximal walking distance (MWD) on a treadmill, resting and postexercise ankle-brachial index, resting and postischemic blood flow (plethysmography), and quality of life (EQ-5D-5L and Vascuqol-6) were measured at baseline and after 12 weeks of treatment. Results: A total of 72 patients were randomized, and 63 had data available for the intention-to-treat analyses. The between-group comparisons showed a significant change in the PWD, favoring the treatment group over the sham control group (estimated treatment effect, 50 m; 95% confidence interval [CI], 11-89; P ¼ .014). The PWD had increased by 68 m (P < .001) in the treatment group and 18 m (P ¼ .064) in the sham control group. No significant difference was found in the change in the MWD between the two groups (estimated treatment effect, 42 m; 95% CI, 14 to 97; P ¼ .139). The MWD had increased by 62 m (P ¼ .006) in the treatment group and 20 m (P ¼ .265) in the sham control group. For patients with a baseline PWD of <200 m (n ¼ 56), significant changes had occurred in both PWD and MWD between the two groups, favoring the treatment group (estimated treatment effect, 42 m; 95% CI, 2-83; P ¼ .042; and estimated treatment effect, 62 m; 95% CI, 5-118; P ¼ .032; respectively). Both overall and for the group of patients with a PWD <200 m, no significant differences were found in the changes in the resting and postexercise ankle-brachial index, resting and postischemic blood flow, or quality of life parameters between the two groups. Conclusions: Treatment with 40 mm Hg INP increased the PWD compared with sham treatment in patients with IC. For the patients with a baseline PWD of <200 m, an increase was found in both PWD and MWD compared with sham treatment. (J Vasc Surg 2021;73:1750-8.)

• Lenz, Harald; Høiseth, Lars Øivind; Comelon, Marlin; Drægni, Tomas & Rosseland, Leiv Arne (2021). Determination of equi-analgesic doses of inhaled methoxyflurane versus intravenous fentanyl using the cold pressor test in volunteers: a randomised, double-blinded, placebo-controlled crossover study. British Journal of Anaesthesia. ISSN 0007-0912. doi: 10.1016/j.bja.2020.12.045. Full text in Research Archive
• Stens, Niels Anton; Hisdal, Jonny; Bakke, Espen; Kaur, Narinder; Sharma, Archana & Stranden, Einar [Show all 8 contributors for this article] (2020). Factors mediating the pressor response to isometric muscle contraction: An experimental study in healthy volunteers during lower body negative pressureFactors mediating the pressor response to isometric muscle contraction: An experimental study in healthy volunteers during lower body negative pressure. PLOS ONE. ISSN 1932-6203. 15:e0243627(12), p. 1–15. doi: 10.1371/journal.pone.0243627. Full text in Research Archive
• Hoff, Ingrid Elise Taraldsrud; Hisdal, Jonny; Landsverk, Svein A.; Røislien, Jo; Kirkebøen, Knut Arvid & Høiseth, Lars Øivind (2019). Respiratory variations in pulse pressure and photoplethysmographic waveform amplitude during positive expiratory pressure and continuous positive airway pressure in a model of progressive hypovolemia. PLOS ONE. ISSN 1932-6203. 14:e0223071(9), p. 1–15. doi: 10.1371/journal.pone.0223071. Full text in Research Archive
• Hoel, Henrik; Høiseth, Lars Øivind; Sandbæk, Gunnar; Sundhagen, Jon Otto; Mathiesen, Iacob & Hisdal, Jonny (2019). The acute effects of different levels of intermittent negative pressure on peripheral circulation in patients with peripheral artery disease. Physiological Reports. ISSN 2051-817X. 7:e14241(20), p. 1–8. doi: 10.14814/phy2.14241. Full text in Research Archive
• Hisdal, Jonny; Landsverk, Svein A.; Hoff, Ingrid Elise Taraldsrud; Hagen, Ove Andreas; Kirkebøen, Knut Arvid & Høiseth, Lars Øivind (2019). Associations between changes in precerebral blood flow and cerebral oximetry in the lower body negative pressure model of hypovolemia in healthy volunteers. PLOS ONE. ISSN 1932-6203. 14(6), p. 1–14. doi: 10.1371/journal.pone.0219154. Full text in Research Archive
• Hoff, Ingrid Elise Taraldsrud; Høiseth, Lars Øivind; Kirkebøen, Knut Arvid & Landsverk, Svein A. (2019). Volumetric and end-tidal capnography for the detection of cardiac output changes in mechanically ventilated patients early after open heart surgery. Critical Care Research and Practice. ISSN 2090-1305. 2019:6393649, p. 1–9. doi: 10.1155/2019/6393649. Full text in Research Archive
• Ottestad, William Arne; Kåsin, Jan Ivar & Høiseth, Lars Øivind (2018). Arterial Oxygen Saturation, Pulse Oximetry, and Cerebral and Tissue Oximetry in Hypobaric Hypoxia. Aerospace Medicine and Human Performance. ISSN 2375-6314. 89(12), p. 1045–1049. doi: 10.3357/AMHP.5173.2018.
• Heiberg Sundby, Øivind; Irgens, Ingebjørg; Høiseth, Lars Øivind; Mathiesen, Iacob; Lundgaard, Eivind & Haugland, Hanne [Show all 10 contributors for this article] (2018). Intermittent mild negative pressure applied to the lower limb in patients with spinal cord injury and chronic lower limb ulcers: A crossover pilot study. Spinal Cord. ISSN 1362-4393. 56, p. 372–381. doi: 10.1038/s41393-018-0080-4.
• Heiberg Sundby, Øivind; Høiseth, Lars Øivind; Irgens, Ingebjørg; Mathiesen, Iacob; Lundgaard, Eivind & Haugland, Hanne [Show all 10 contributors for this article] (2017). Intermittent negative pressure applied to the lower limb increases foot macrocirculatory and microcirculatory blood flow pulsatility in people with spinal cord injury. Spinal Cord. ISSN 1362-4393. p. 1–10. doi: 10.1038/s41393-017-0049-8.
• Ottestad, William Arne; Hansen, Tor Are; Pradhan, Gaurav; Stepanek, Jan; Høiseth, Lars Øivind & Kåsin, Jan Ivar (2017). Acute hypoxia in a simulated high-altitude airdrop scenario due to oxygen system failure. Journal of applied physiology. ISSN 8750-7587. 123, p. 1443–1450. doi: 10.1152/japplphysiol.00169.2017.
• Høiseth, Lars Øivind & Hagemo, Jostein Skjalg (2017). Predicting fluid responsiveness in whom? A simulated example of patient spectrum influencing the receiver operating characteristics curve. Journal of clinical monitoring and computing. ISSN 1387-1307. 32(2), p. 215–219. doi: 10.1007/s10877-017-0019-x.
• Sundby, Øyvind Heiberg; Høiseth, Lars Øivind; Mathiesen, Iacob; Weedon-Fekjær, Harald; Sundhagen, Jon Otto & Hisdal, Jonny (2017). The acute effects of lower limb intermittent negative pressure on foot macro-and microcirculation in patients with peripheral arterial disease. PLOS ONE. ISSN 1932-6203. 12:e0179001(6), p. 1–16. doi: 10.1371/journal.pone.0179001. Full text in Research Archive
• Sundby, Øyvind Heiberg; Høiseth, Lars Øivind; Mathiesen, Iacob; Jørgensen, Jørgen J.; Sundhagen, Jon Otto & Hisdal, Jonny (2016). The effects of intermittent negative pressure on the lower extremities' peripheral circulation and wound healing in four patients with lower limb ischemia and hard‐to‐heal leg ulcers: a case report. Physiological Reports. ISSN 2051-817X. 4(20). doi: 10.14814/phy2.12998. Full text in Research Archive Show summary

  Peripheral circulation is severely compromised in the advanced stages of peripheral arterial disease. Recently, it was shown that the application of −40 mmHg intermittent negative pressure (INP) to the lower leg and foot enhances macro‐ and microcirculation in healthy volunteers. In this case report, we describe the effects of INP treatment on four patients with lower limb ischemia and hard‐to‐heal leg and foot ulcers. We hypothesized that INP therapy may have beneficial hemodynamic and clinical effects in the patients. Four patients (age range: 61–79 years) with hard‐to‐heal leg and foot ulcers (6–24 months) and ankle‐brachial pressure indices of ≤0.60 on the affected side were included. They were treated with an 8‐week intervention period of −40 mmHg INP (10 sec negative pressure and 7 sec atmospheric pressure) on the lower limbs. A custom‐made vacuum chamber was used to apply INP to the affected lower leg and foot for 2 h per day. After 8 weeks of INP therapy, one ulcer healed completely, while the other three ulcers were almost completely healed. These cases suggest that INP may facilitate wound healing. The theoretical foundation is that INP assists wound healing by improving blood flow to the small blood vessels in the affected limb, increasing the flow of oxygen and nutrients to the cells.

• Sundby, Øyvind Heiberg; Høiseth, Lars Øivind; Mathiesen, Iacob; Jørgensen, Jørgen J.; Weedon-Fekjær, Harald & Hisdal, Jonny (2016). Application of intermittent negative pressure on the lower extremity and its effect on macro- and microcirculation in the foot of healthy volunteers. Physiological Reports. ISSN 2051-817X. 4(17). doi: 10.14814/phy2.12911. Full text in Research Archive
• Rimehaug, Audun Eskeland; Hoff, Ingrid E Taraldsrud; Høiseth, Lars Øivind; Hisdal, Jonny; Aadahl, Petter & Kirkeby-Garstad, Idar (2016). Cardiac power parameters during hypovolemia, induced by the lower body negative pressure technique, in healthy volunteers. BMC Anesthesiology. ISSN 1471-2253. 16(31). doi: 10.1186/s12871-016-0195-0. Full text in Research Archive Show summary

  Background Changes in cardiac power parameters incorporate changes in both aortic flow and blood pressure. We hypothesized that dynamic and non-dynamic cardiac power parameters would track hypovolemia better than equivalent flow- and pressure parameters, both during spontaneous breathing and non-invasive positive pressure ventilation (NPPV). Methods Fourteen healthy volunteers underwent lower body negative pressure (LBNP) of 0, −20, −40, −60 and −80 mmHg to simulate hypovolemia, both during spontaneous breathing and during NPPV. We recorded aortic flow using suprasternal ultrasound Doppler and blood pressure using Finometer, and calculated dynamic and non-dynamic parameters of cardiac power, flow and blood pressure. These were assessed on their association with LBNP-levels. Results Respiratory variation in peak aortic flow was the dynamic parameter most affected during spontaneous breathing increasing 103 % (p < 0.001) from baseline to LBNP −80 mmHg. Respiratory variation in pulse pressure was the most affected dynamic parameter during NPPV, increasing 119 % (p < 0.001) from baseline to LBNP −80 mmHg. The cardiac power integral was the most affected non-dynamic parameter falling 59 % (p < 0.001) from baseline to LBNP −80 mmHg during spontaneous breathing, and 68 % (p < 0.001) during NPPV. Conclusions Dynamic cardiac power parameters were not better than dynamic flow- and pressure parameters at tracking hypovolemia, seemingly due to previously unknown variation in peripheral vascular resistance matching respiratory changes in hemodynamics. Of non-dynamic parameters, the power parameters track hypovolemia slightly better than equivalent flow parameters, and far better than equivalent pressure parameters.

• Hagen, Ove Andreas; Høiseth, Lars Øivind; Roslin, Andre; Landsverk, Svein A.; Woldbæk, Per R & Pripp, Are Hugo [Show all 8 contributors for this article] (2016). Impact of Norepinephrine on Regional Cerebral Oxygenation During Cardiopulmonary Bypass. Journal of Cardiothoracic and Vascular Anesthesia. ISSN 1053-0770. 30(2), p. 291–296. doi: 10.1053/j.jvca.2015.12.015.
• Høiseth, Lars Øivind; Hoff, Ingrid E Taraldsrud; Hagen, Ove Andreas; Kirkebøen, Knut Arvid & Landsverk, Svein A. (2016). Respiratory variations in the photoplethysmographic waveform amplitude depend on type of pulse oximetry device. Journal of clinical monitoring and computing. ISSN 1387-1307. 30(3), p. 317–325. doi: 10.1007/s10877-015-9720-9.
• Høiseth, Lars Øivind; Hisdal, Jonny; Hoff, Ingrid E Taraldsrud; Hagen, Ove Andreas; Landsverk, Svein A. & Kirkebøen, Knut Arvid (2015). Tissue Oxygen Saturation and Finger Perfusion Index in Central Hypovolemia: Influence of Pain. Critical Care Medicine. ISSN 0090-3493. 43(4). doi: 10.1097/CCM.0000000000000766. Show summary

  Objectives: Tissue oxygen saturation and peripheral perfusion index are proposed as early indirect markers of hypovolemia in trauma patients. Hypovolemia is associated with increased sympathetic nervous activity. However, many other stimuli, such as pain, also increase sympathetic activity. Since pain is often present in trauma patients, its effect on the indirect measures of hypovolemia needs to be clarified. The aim of this study was, therefore, to explore the effects of hypovolemia and pain on tissue oxygen saturation (measurement sites: cerebral, deltoid, forearm, and thenar) and finger photoplethysmographic perfusion index. Design: Experimental study. Setting: University hospital clinical circulation and research laboratory. Subjects: Twenty healthy volunteers. Interventions: Central hypovolemia was induced with lower body negative pressure (–60 mm Hg) and pain by the cold pressor test (ice water exposure). Interventions were performed in a 2 × 2 fashion with the combination of lower body negative pressure or not (normovolemia), and ice water or not (sham). Each subject was thus exposed to four experimental sequences, each lasting for 8 minutes. Measurements and Main Results: Measurements were averaged over 30 seconds. For each person and sequence, the minimal value was analyzed. Tissue oxygenation in all measurement sites and finger perfusion index were reduced during hypovolemia/sham compared with normovolemia/sham. Tissue oxygen saturation (except cerebral) and perfusion index were reduced by pain during normovolemia. There was a larger reduction in tissue oxygenation (all measurement sites) and perfusion index during hypovolemia and pain than during normovolemia and pain. Conclusions: Pain (cold pressor test) reduces tissue oxygen saturation in all measurement sites (except cerebral) and perfusion index. In the presence of pain, tissue oxygen saturation and perfusion index are further reduced by hypovolemia (lower body negative pressure, –60 mm Hg). Thus, pain must be considered when evaluating tissue oxygen saturation and perfusion index as markers of hypovolemia in trauma patients.

• Høiseth, Lars Øivind; Hoff, Ingrid E Taraldsrud; Hagen, Ove Andreas; Landsverk, Svein A. & Kirkebøen, Knut Arvid (2015). Agreement between stroke volume measured by oesophageal Doppler and uncalibrated pulse contour analysis during fluid loads in severe aortic stenosis. Journal of clinical monitoring and computing. ISSN 1387-1307. 29(4), p. 435–441. doi: 10.1007/s10877-015-9666-y.
• Hoff, Ingrid E Taraldsrud; Høiseth, Lars Øivind; Hisdal, Jonny; Røislien, Jo; Landsverk, Svein A. & Kirkebøen, Knut Arvid (2014). Respiratory variations in pulse pressure reflect central hypovolemia during noninvasive positive pressure ventilation. Critical Care Research and Practice. ISSN 2090-1305. 2014. doi: 10.1155/2014/712728.
• Høiseth, Lars Øivind; Hoff, Ingrid E Taraldsrud; Hagen, Ove Andreas; Landsverk, Svein A. & Kirkebøen, Knut Arvid (2014). Dynamic variables and fluid responsiveness in patients for aortic stenosis surgery. Acta Anaesthesiologica Scandinavica. ISSN 0001-5172. 58(7), p. 826–834. doi: 10.1111/aas.12328.
• Høiseth, Lars Øivind; Hoff, Ingrid E Taraldsrud; Myre, Kirsti; Landsverk, Svein A. & Kirkebøen, Knut Arvid (2012). Dynamic variables of fluid responsiveness during pneumoperitoneum and laparoscopic surgery. Acta Anaesthesiologica Scandinavica. ISSN 0001-5172. 56(6), p. 777–786. doi: 10.1111/j.1399-6576.2011.02641.x.
• Høiseth, Lars Øivind; Hoff, Ingrid E Taraldsrud; Skare, Øivind; Kirkebøen, Knut-Arvid & Landsverk, Svein A. (2011). Photoplethysmographic and pulse pressure variations during abdominal surgery. Acta Anaesthesiologica Scandinavica. ISSN 0001-5172. 55(10), p. 1221–1230. doi: 10.1111/j.1399-6576.2011.02527.x.

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• Lie, Sole Lindvåg; Hisdal, Jonny; Rehn, Marius & Høiseth, Lars Øivind (2022). Effects of supplemental oxygen on systemic and cerebral hemodynamics in experimental hypovolemia: Protocol for a randomized, double blinded crossover study. PLOS ONE. ISSN 1932-6203. 17(6). doi: 10.1371/journal.pone.0270598. Show summary

  Supplemental oxygen is widely administered in trauma patients, often leading to hyperoxia. However, the clinical evidence for providing supplemental oxygen in all trauma patients is scarce, and hyperoxia has been found to increase mortality in some patient populations. Hypovolemia is a common finding in trauma patients, which affects many hemodynamic parameters, but little is known about how supplemental oxygen affects systemic and cerebral hemodynamics during hypovolemia. We therefore plan to conduct an experimental, randomized, double blinded crossover study to investigate the effect of 100% oxygen compared to room air delivered by a face mask with reservoir on systemic and cerebral hemodynamics during simulated hypovolemia in the lower body negative pressure model in 15 healthy volunteers. We will measure cardiac output, stroke volume, blood pressure, middle cerebral artery velocity and tolerance to hypovolemia continuously in all subjects at two visits to investigate whether oxygen affects the cardiovascular response to simulated hypovolemia. The effect of oxygen on the outcome variables will be analyzed with mixed linear regression. Trial registration: The study is registered in the European Union Drug Regulating Authorities Clinical Trials Database (EudraCT, registration number 2021-003238-35).

• Høiseth, Lars Øivind & Hagemo, Jostein Skjalg (2016). Comparing measurement methods using linear least squares regression. Journal of clinical monitoring and computing. ISSN 1387-1307. 32(2), p. 373–374. doi: 10.1007/s10877-016-9955-0.
• Høiseth, Lars Øivind; Hisdal, Jonny; Landsverk, Svein A. & Kirkebøen, Knut Arvid (2015). The authors reply: Pain and tissue oxygenation. Critical Care Medicine. ISSN 0090-3493. 43(10), p. e463–e464. doi: 10.1097/CCM.0000000000001206.

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