Biomedical subjects

Einar Thorsen

Publications and source records attributed to Einar Thorsen.

5 recordsLinked to original sources

PubMed2006

Hypermetropia-succeeded myopia after hyperbaric oxygen therapy.

A 58-year-old man presented with a change in vision during hyperbaric oxygen (HBO) therapy. Subsequent follow-up visits showed a hypermetropic shift, which succeeded the myopic shift after each of two series of HBO treatments. The maximal refractive amplitude was 3.00 D (range -1.37 D to +1.62 D) in the right eye and 2.75 D (range -1.25 D to + 1.50 D) in the left eye. Refraction stabilized after 1.5 years at +0.62 D and +0.50 D to pretreatment values in the right and left eye, respectively. The findings are discussed with regard to possible changes in the structure of the lens.

Follow-Up Studies↗

PubMed2005

Changes in erythropoietin and haemoglobin concentrations in response to saturation diving.

A reduction in haemoglobin concentration is consistently reported after deep saturation dives. This may be due to a downregulation of erythropoietin (EPO) concentration or to a toxic effect of the hyperoxia associated with the dives resulting in an increased destruction rate of erythrocytes. In this study haemoglobin concentration, blood cell counts, serum ferritin, bilirubin, haptoglobin and EPO concentrations were measured before, during and after a 19 day saturation dive to 240 m. The partial pressure of oxygen (PO(2)) was 35-70 kPa during the 7 day compression and bottom phase, and 30-50 kPa during the 12 day decompression phase. There was a reduction in EPO concentration from 8.4+/-1.4 (mean +/- 1SD) to 6.3 +/- 1.9 U.L(-1) on Dive day 2. On Dive days 7 and 17 EPO concentrations were not significantly different from baseline despite the continued exposure to hyperoxia. Immediately after the dive and return to a normoxic environment there was an increase in the EPO concencentration to 14.5 +/- 4.7 U.L(-1). Haemoglobin concentration, erythrocyte and reticulocyte counts were decreased at the end of the dive, and there was an increase in serum ferritin. There were no changes in bilirubin or haptoglobin concentrations indicative of haemolysis. It appears that the change in PO(2), rather than the sustained exposure to a hyperoxic environment, induces the changes in the EPO concentrations and erythropoietic activity.

Adult↗

PubMed2005

Breathing at depth: physiologic and clinical aspects of diving while breathing compressed gas.

When diving, human beings are exposed to hazards that are unique to the hyperbaric underwater environment and the physical behavior of gases at higher ambient pressure. Hypercapnia, hyperoxia, carbon monoxide intoxication, inert gas (predominantly nitrogen) narcosis, and decompression illness all may lead to impaired consciousness, with a high risk of drowning in this non-respirable environment. Proper physiologic function and adaptation of the respiratory system are of the utmost importance to minimize the risks associated with compressed gas diving. This article provides an introduction to the diving techniques, the physics, and the pertinent human physiology and pathophysiology associated with this extreme environment. The causes of the major medical problems encountered in diving are described, with an emphasis on the underlying respiratory physiology.

Barotrauma↗

PubMed2005

Assessment of lung volumes in children and adolescents: comparison of two plethysmographic techniques.

Thoracic gas volume (Vtg) can be measured with body plethysmography by either repetitive panting or one single inspiratory effort against a shutter occluding the airways. The panting technique is preferred, but may be demanding. We aimed to assess the precision of these two methods and the degree of agreement between them. Vtg and functional residual capacity (FRC) were measured in 155 subjects with a standard, commercially available plethysmograph, acting as a variable-pressure, constant-volume device when Vtg is determined. Total lung capacity (TLC) and residual lung volume (RV) were calculated subsequent to a full vital capacity manoeuvre. For non-asthmatic healthy subjects, the standard deviations (SD) of the differences between two replicate measurements of FRC, TLC and RV were respectively 0.16, 0.13 and 0.14 litres with the panting technique, and 0.18, 0.18 and 0.23 litres with the single inspiratory effort technique. In percentage of the respective lung volumes, the corresponding 1.96 SDs were 20%, 8% and 40% with the panting technique and 23%, 12% and 67% with the single inspiratory effort technique. Between the two techniques, 95% limits of agreement were 21% for FRC, 11% for TLC and 58% for RV. The variability of Vtg and FRC accounted for most of the variability of TLC and RV. In conclusion, the panting and the single inspiratory effort technique produced results that were comparable in magnitude, however with a better precision with the panting technique. The single inspiratory effort technique can be used as an alternative if the panting technique fails.

Adolescent↗

PubMed2004

Ocular refractive changes in patients receiving hyperbaric oxygen administered by oronasal mask or hood.

PURPOSE: The aim of this study was to quantify ocular refractive changes after a standard hyperbaric oxygen (HBO) treatment protocol and to characterize the time period of recovery. PATIENTS AND METHODS: Hyperbaric oxygen therapy was given for 90 min daily at a pressure of 240 kPa for 21 days. Oxygen was administered to 20 patients using an oronasal mask and to 12 patients using a hood. Follow-up examinations were carried out 2-4 days after treatment, and thereafter regularly for up to 10 weeks in both groups. Refraction was assessed automatically and by the monocular subjective refraction method. A subgroup of nine of the 20 patients to whom oxygen was administered by an oronasal mask underwent a separate eye examination, which included crystalline lens opacity measurements and LOCS III gradings. RESULTS: In the patients given oxygen by mask, there was a significant myopic shift in the mean spherical equivalent, which was largest 2-4 days after treatment. The shift was - 0.55 +/- 0.40 D in the right eye and - 0.53 +/- 0.42 D in the left eye. In the patients given oxygen by hood, the largest shift was observed after 12-16 days, and was - 1.06 +/- 0.52 D in the right eye and - 1.10 +/- 0.57 D in the left eye. The refractive changes returned to baseline 6 weeks and 10 weeks after HBO treatment, respectively. No significant changes in crystalline lens transparency were revealed. CONCLUSIONS: The myopic shift after HBO therapy recovers within 10 weeks and may be more pronounced when patients are given oxygen using a hood compared with using an oronasal mask.

Cystitis↗