Biomedical subjects

J Jahr

Publications and source records attributed to J Jahr.

14 recordsLinked to original sources

PubMed2003

Effects of pneumoperitoneum on intraoperative pulmonary mechanics and gas exchange during laparoscopic gastric bypass.

BACKGROUND: Hypercarbia and elevated intraabdominal pressure resulting from carbon dioxide (CO2) pneumoperitoneum can adversely affect respiratory mechanics. This study examined the changes in mechanical ventilation, CO2 homeostasis, and pulmonary gas exchange in morbidly obese patients undergoing a laparoscopic or open gastric bypass (GBP) procedure. METHODS: In this study, 58 patients with a body mass index (BMI) of 40 to 60 kg/m2 were randomly allocated to laparoscopic ( n = 31) or open ( n = 27) GBP. Minute ventilation was adjusted to maintain a low normal arterial partial pressure of CO2 (PaCO2), low normal end-tidal partial pressure of CO2 (ETCO2), and low airway pressure. Respiratory compliance, ETCO2, peak inspiratory pressure (PIP), total exhaled CO2 per minute (VCO2), and pulse oximetry (SO2) were measured at 30-min intervals. The acid-base balance was determined by arterial blood gas analysis at 1-h intervals. The pulmonary gas exchange was evaluated by calculation of the alveolar dead space-to-tidal volume ratio (V(Dalv)/V(T)) and alveolar-arterial oxygen gradient (PAO2-PaO2). RESULTS: The two groups were similar in age, gender, and BMI. As compared with open GBP, laparoscopic GBP resulted in higher ETCO2, PIP, and VCO2, and a lower respiratory compliance. Arterial blood gas analysis demonstrated higher PaCO2 and lower pH during laparoscopic GBP than during open GBP ( p < 0.05). The V(Dalv)/V(T) ratio and PAO2-PaO2 gradient did not change significantly during laparoscopic GBP. Intraoperative oxygen desaturation (SO2 < 90%) did not develop in any of the patients in either group. CONCLUSIONS: Laparoscopic GBP alters intraoperative pulmonary mechanics and acid-base balance but does not significantly affect pulmonary oxygen exchange. Changes in pulmonary mechanics are well tolerated in morbidly obese patients when proper ventilator adjustments are maintained.

Acid-Base Equilibrium↗

PubMed2003

Exotic snake bite: a challenge for the Scandinavian anesthesiologist?

BACKGROUND: Venomous snake bites are uncommon in the Scandinavian countries. Envenomation from exotic snakes do however occur, mostly amongst snake handlers. This case report documents the effects and treatment for envenomation from Hoplocephalus bungaroides, or the Broad-Headed snake, native to eastern and southern Australia. Snakes of the genus Hoplocephalus have previously been described as of 'lesser medical importance' because of their rarity. METHODS: This case report describes the signs, symptoms and management of systemic envenomation in a previously healthy man. RESULTS: The patient developed signs of severe coagulopathy less than an hour after envenomation. There was also biochemical evidence of rhabdomyolysis, and cardiotoxicity. At no time did the patient develop respiratory insufficiency, neurotoxicity or renal failure. The patient was initially managed with i.v. crystalloids, plasma, corticosteroids and antifibrinolytics and by observation in the intensive care unit (ICU). Coagulopathy resolved after causal treatment with monovalent Tiger snake antivenom. CONCLUSION: The patient made good progress and was well on discharge from the ICU 26 h postenvenomation.

Adult↗

PubMed1997

Peripheral circulatory effects of pump perfusion on cat skeletal muscle with and without prostacyclin.

The present study analyses the peripheral circulatory effects of pump perfusion on a sympathectomized cat skeletal muscle in terms of effects on segmental vascular resistances (large-bore arterial vessels, arterioles and veins), hydrostatic capillary pressure, capillary filtration coefficient, transcapillary filtration and autoregulation of blood flow. The effect of prostacyclin during pump perfusion was analysed to evaluate whether it interferes with the pump-induced vascular alterations, especially if it reduces transcapillary filtration through its capillary permeability decreasing effect. Pump perfusion initiates a marked vasodilation (from 17.3 to 10.1 PRU), an increase in hydrostatic capillary pressure, and a marked inhibition of myogenic reactivity and of autoregulation of blood flow. There was a slow restoration of vascular tone reaching a steady-state level somewhat below the autoperfusion value within 2 h. Pump perfusion did not change the capillary filtration coefficient, indicating that the capillary permeability was not increased. This implies that short-term pump-induced capillary leakage is more an effect of increase in hydrostatic capillary pressure, perhaps in combination with increased number of open capillaries, than of an increase in capillary permeability. Prostacyclin decreased capillary permeability by at least 22% but simultaneously increased hydrostatic capillary pressure, resulting in an unchanged filtration compared with the situation just after the starting of the pump. The results obtained show that experiments using pump perfusion should be interpreted with care due to the interference with normal peripheral vascular control. The results give reasonable explanations of the lowered blood pressure and transcapillary fluid loss during the clinical use of a heart-lung machine.

Animals↗

PubMed1996

Prostacyclin counteracts the increase in capillary permeability induced by tumour necrosis factor-alpha.

OBJECTIVE: To analyse how prostacyclin interferes with the short-term local circulatory effects of tumour necrosis factor-alpha (TNF alpha) in a skeletal muscle. DESIGN: An autoperfused sympathectomised cat gastrocnemius muscle enclosed in a plethysmograph. INTERVENTIONS: Arterial blood flow, total and segmental vascular resistances (large-bore arterial vessels, arterioles and veins), hydrostatic capillary pressure, tissue volume and capillary filtration coefficient were followed during local intra-arterial infusion of TNF alpha at various rates (2.5, 5.0 and 7.5 micrograms/kg per min) and during intra-arterial infusion of prostacyclin simultaneously with the highest dose of TNF alpha. The capillary filtration coefficient reflects the capillary surface for fluid exchange. RESULTS: Arterial infusion of TNFx had no influence on vascular resistance up to 5.0 micrograms/kg per min but induced vasodilation at 7.5 micrograms/kg per min. No effects on the recorded hydrostatic capillary pressure were observed. The capillary filtration coefficient and the capillary filtration increased with the infusion rate of TNF alpha, the former by 55%. Simultaneous arterial infusion of prostacyclin (350 ng/kg per min) caused further vasodilation and an increase in hydrostatic capillary pressure and completely restored the capillary filtration coefficient to control. The TNF alpha-induced filtration was partly restored. CONCLUSIONS: The local circulatory effect of TNF alpha is small apart from a graded increase in the capillary filtration coefficient, most likely reflecting an increase in the capillary permeability. The prostacyclin-induced decrease in capillary filtration coefficient most likely reflects a restoration of capillary permeability. The TNF alpha-induced transcapillary filtration is not fully reduced by prostacyclin due to a simultaneous increase in hydrostatic capillary pressure.

Animals↗

PubMed1996

Biological responses differ considerably between endovascular and conventional aortic aneurysm surgery.

OBJECTIVES: To determine the inflammatory responses in endovascular abdominal aortic aneurysm (AAA) repair and their relation to clinical findings. DESIGN: Prospective non-randomised study. SETTING: University Hospital, Department of Surgery. PATIENTS AND METHODS: Seven patients treated with an endoluminal procedure (AAA-E) and seven patients undergoing conventional surgery (AAA-C) were included. Inflammatory parameters were assessed by measurements of the cytokines interleukin (IL)-1 beta, IL-6, IL-8 and Tumour Necrosis Factor-alpha (TNF-alpha); analyses of complement proteins C1q, C4, C3, C5a and Terminal Complement Complexes (TCC); haematologic parameters and determination of C-reactive protein (CRP). RESULTS: In six of seven patients in the AAA-E group blood pressure decreases were recorded during introduction of the device. IL-6 and CRP levels were found to be significantly higher in AAA-C patients compared to the AAA-E group. On the other hand, high TNF-alpha levels were recorded in the AAA-E group. Less consumption of the complement proteins C1q, C4 and C3 was observed in AAA-E compared to AAA-C patients. Increased C5a levels were recorded in the AAA-C group, whereas only slight fluctuations were noticed in the AAA-E group. TCC levels were unchanged in both groups. CONCLUSION: Endovascular aortic aneurysm repair induced a significant inflammatory response, mainly involving TNF-alpha and differing from the findings during open AAA repair. These inflammatory responses were probably related to blood pressure decreases during the procedures. On the other hand, conventional repair induced responses related to the more extensive surgical trauma and reperfusion injury.

Aged↗

PubMed1996

In vivo effects of tumor necrosis factor-alpha on capillary permeability and vascular tone in a skeletal muscle.

BACKGROUND: The present study aims at analysing short-term effects of TNF alpha on capillary permeability, on transcapillary fluid fluxes, and on vascular tone in a whole organ cat skeletal muscle in vivo preparation. METHODS: The denervated muscle was isolated from the body but with intact vascular supply. The experimental setup allowed continuous recording of vascular tone, of hydrostatic capillary pressure and tissue volume variations. The capillary filtration coefficient (CFC), which represents the net effect for transcapillary fluid exchange of capillary permeability and number of open capillaries, was calculated before and during intra-arterial TNF infusion. RESULTS: We found that TNF had a minor effect on vascular tone in terms of a small vasodilation, and that no effect on hydrostatic capillary pressure could be recorded. CFC increased by 64% during the TNF infusion and this increase must be attributed to an increase in capillary permeability rather than an increase in the number of capillaries available for fluid exchange since the TNF effect on vascular tone is small. This was also supported by TNF-induced transcapillary filtration. CONCLUSIONS: TNF is a potent drug for increasing capillary permeability causing transcapillary filtration in vivo. Its release, e.g. during sepsis, may therefore contribute to the capillary leakage often seen in this clinical situation.

Animals↗

PubMed1995

In vivo effects of prostacyclin on segmental vascular resistances, on myogenic reactivity, and on capillary fluid exchange in cat skeletal muscle.

OBJECTIVE: To analyze the local circulatory effects of prostacyclin in skeletal muscle. DESIGN: A prospective experimental study. SETTING: A university laboratory. SUBJECTS: Twelve adult cats. INTERVENTIONS: The study was performed on autoperfused, sympathectomized gastrocnemius muscle. MEASUREMENTS AND MAIN RESULTS: Arterial blood flow, total and segmental vascular resistances (arterial vessels of > 25 microns, arterioles of < 25 microns, and veins), hydrostatic capillary pressure, tissue volume, myogenic reactivity, and the capillary filtration coefficient were followed. The capillary filtration coefficient reflects the functional capillary fluid exchange area. Myogenic reactivity was evaluated as the arteriolar resistance increase after a standardized decrease in extravascular pressure. Arterial infusion of prostacyclin decreased vascular resistance by approximately 50% at the highest dose given (500 ng/kg/min). This effect was more pronounced on the arterial side, especially in arterial vessels of > 25 microns. Hydrostatic capillary pressure increased by 1.9 +/- 0.3 mm Hg, causing fluid filtration. The relative fluid filtration was less than that value shown for some other vasodilator drugs (isoprenaline, calcium-channel blockers, thiopental) in this muscle preparation. Capillary filtration coefficient decreased by 25%. Myogenic reactivity was depressed but to a lesser extent than previously observed for other vasodilator mechanisms (muscle exercise, beta-adrenergic receptor stimulation, thiopental infusion, nifedipine infusion). CONCLUSIONS: Prostacyclin is a vasodilator, both on the arterial and venous side, that restricts the increase in hydrostatic capillary pressure. The decrease in capillary filtration coefficient most likely reflects a decrease in capillary permeability, explaining the smaller relative filtration rate. The relatively well-preserved myogenic reactivity may imply a better preserved microvascular flow distribution and peripheral oxygen uptake.

Animals↗

PubMed1992

Pulmonary and haemodynamic effects of extracorporeal circulation in the cat and the beneficial effects of prostacyclin.

Side-effects of a veno-venous extracorporeal system and possible beneficial effects of prostacyclin (epoprostenol) are analyzed on the cat. Three groups were studied; one control group without extracorporeal circulation and two groups with an extracorporeal flow of 10-12 ml/kg/min, one of which was given prostacyclin (70-110 ng/kg/min). The extracorporeal circulation triggered a decrease in arterial saturation (from 99 to 91%) and carbon dioxide elimination (increase in arterial to end-tidal PCO2 by about 1 kpa) a metabolic acidosis (pH approximately 7.20), a platelet consumption (approximately 50%) and shortened survival time, side-effects reduced by prostacyclin. Further, there was a marked increase in haemoglobin concentration indicating hypovolemia via capillary fluid filtration. None of these side-effects were seen in the control group. Extracorporeal circulation as a trigger for pulmonary dysfunction and for impaired tissue nutrition with possible beneficial effects of prostacyclin is discussed, and also form a clinical point of view (i.e. extracorporeal lung assistance, ECLA), on the basis of the results.

Animals↗

PubMed1990

Dynamic pulmonary accumulation of labelled neutrophils by blood membrane contact in the pig.

Nine anesthetized pigs were subjected to short (90 min) sham dialysis with blood membrane contact with the aim to select effects of the artificial surface during dialysis. The importance of the neutrophil (PMN) was investigated by the selective isotope labelling, dynamically followed by gamma-camera imaging and biochemical assays specifically oriented for PMN function. These assays included cell count, PMN aggregation, PMN luminescence, fibronectin and catalase activity. Additionally, pulmonary and systemic hemodynamics and acid base balance were monitored. Sham dialysis induced an accumulation of labelled PMN attaining a maximum between 15 and 17 min. This was coupled with a time-related neutropenia, pulmonary vasoconstriction, increased in vitro PMN aggregation and luminescence response. The neutrophil response abated by the end of dialysis. Cardiac output and arterial blood pressure declined to a steady level after 30 min of sham dialysis. There was an insignificant decrease in catalase activity. All other parameters remained unaltered. The results indicate that PMN accumulates in the pulmonary vessels, in association with neutropenia and activation. The transience of the event points to a protective mechanisms of humoral and/or cellular character.

Animals↗

PubMed1989