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- Bak, Zoltan, et al.
(författare)
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Cardiac dysfunction after burns
- 2008
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Ingår i: Burns. - : Elsevier BV. - 0305-4179 .- 1879-1409. ; 34:5, s. 603-609
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Using transoesophageal echocardiography (TEE) we investigated the occurrence, and the association of possible abnormalities of motion of the regional wall of the heart (WMA) or diastolic dysfunction with raised troponin concentrations, or both during fluid resuscitation in patients with severe burns. PATIENTS AND METHODS: Ten consecutive adults (aged 36-89 years, two women) with burns exceeding 20% total burned body surface area who needed mechanical ventilation were studied. Their mean Baux index was 92.7, and they were resuscitated according to the Parkland formula. Thirty series of TEE examinations and simultaneous laboratory tests for myocyte damage were done 12, 24, and 36h after the burn. RESULTS: Half (n=5) the patients had varying grades of leakage of the marker that correlated with changeable WMA at 12, 24 and 36h after the burn (p< or =0.001, 0.044 and 0.02, respectively). No patient had WMA and normal concentrations of biomarkers or vice versa. The mitral deceleration time was short, but left ventricular filling velocity increased together with stroke volume. CONCLUSION: Acute myocardial damage recorded by both echocardiography and leakage of troponin was common, and there was a close correlation between them. This is true also when global systolic function is not deteriorated. The mitral flow Doppler pattern suggested restrictive left ventricular diastolic function.
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| 2. |
- Bak, Zoltan, et al.
(författare)
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Hemodynamic Changes During Resuscitation After Burns Using the Parkland Formula
- 2009
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Ingår i: Journal of Trauma. - 0022-5282 .- 1529-8809. ; 66:2, s. 329-336
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Tidskriftsartikel (refereegranskat)abstract
- Background: The Parkland formula (2-4 mL/kg/burned area of total body surface area %) with urine output and mean arterial pressure (MAP) as endpoints; for the fluid resuscitation in burns is recommended all over the world. There has recently been a discussion on whether central circulatory endpoints should be used instead, and also whether volumes of fluid should be larger. Despite this, there are few central hemodynamic data available in the literature about the results when the formula is used correctly.Methods: Ten burned patients, admitted to our unit early, and with a burned area of >20% of total body sur-face area were investigated at 12, 24, and 36 hours after injury. Using transesophageal echocardiography, pulmonary artery catheterization, and transpulmonary thermodilution to monitor them, we evaluated the cardiovascular coupling when urinary output and MAP were used as endpoints.Results: Oxygen transport variables, heart rate, MAP, and left ventricular fractional area, did not change significantly during fluid resuscitation. Left ventricular end-systolic and end-diastolic area and global end-diastolic volume index increased from subnormal values at 12 hours to normal ranges at 24 hours after the burn. Extravascular lung intrathoracal blood volume ratio was increased 12 hours after the burn.Conclusions: Preload variables, global systolic function, and oxygen transport recorded simultaneously by three separate methods showed no need to increase the total fluid volume within 36 hours of a major burn. Early (12 hours) signs of central circulatory hypovolemia, however, support more rapid infusion of fluid at the beginning of treatment.
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| 3. |
- Bak, Zoltan, et al.
(författare)
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Human cardiovascular dose-response to supplemental oxygen
- 2007
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 191:1, s. 15-24
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of the study was to examine the central and peripheral cardiovascular adaptation and its coupling during increasing levels of hyperoxaemia. We hypothesized a dose-related effect of hyperoxaemia on left ventricular performance and the vascular properties of the arterial tree. Methods: Oscillometrically calibrated arterial subclavian pulse trace data were combined with echocardiographic recordings to obtain non-invasive estimates of left ventricular volumes, aortic root pressure and flow data. For complementary vascular parameters and control purposes whole-body impedance cardiography was applied. In nine (seven males) supine, resting healthy volunteers, aged 23–48 years, data was collected after 15 min of air breathing and at increasing transcutaneous oxygen tensions (20, 40 and 60 kPa), accomplished by a two group, random order and blinded hyperoxemic protocol. Results: Left ventricular stroke volume [86 ± 13 to 75 ± 9 mL (mean ± SD)] and end-diastolic area (19.3 ± 4.4 to 16.8 ± 4.3 cm2) declined (P < 0.05), and showed a linear, negative dose–response relationship to increasing arterial oxygen levels in a regression model. Peripheral resistance and characteristic impedance increased in a similar manner. Heart rate, left ventricular fractional area change, end-systolic area, mean arterial pressure, arterial compliance or carbon dioxide levels did not change. Conclusion: There is a linear dose–response relationship between arterial oxygen and cardiovascular parameters when the systemic oxygen tension increases above normal. A direct effect of supplemental oxygen on the vessels may therefore not be excluded. Proximal aortic and peripheral resistance increases from hyperoxaemia, but a decrease of venous return implies extra cardiac blood-pooling and compensatory relaxation of the capacitance vessels.
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| 4. |
- Rousseau, Andreas, 1971-, et al.
(författare)
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Acute hyperoxaemia-induced effects on regional blood flow, oxygen consumption and central circulation in man
- 2005
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 183:3, s. 231-240
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Despite numerous in vitro and animal studies, circulatory effects and mechanisms responsible for the vasoconstriction seen during hyperoxaemia are yet to be ascertained. The present study set out to: (i) set up a non-invasive human model for the study of hyperoxia-induced cardiovascular effects, (ii) describe the dynamics of this effect and (iii) determine whether hyperoxaemia also, by vasoconstriction alters oxygen consumption (O2).Methods: The study comprised four experiments (A, B, C and D) on healthy volunteers examined before, during and after 100% oxygen breathing. A: Blood flow (mL min−1·100 mL−1 tissue), venous occlusion plethysmography was assessed (n = 12). B: Blood flow was recorded with increasing transcutaneous oxygen tension (PtcO2) levels (dose–response) (n = 8). C: Heart rate (HR), stroke volume, cardiac output (CO) and systemic vascular resistance (SVR) was assessed using echocardiography (n = 8). D: O2 was measured using an open circuit technique when breathing an air-O2 mix (fraction of inhaled oxygen: FiO2 = 0.58) (n = 8).Results: Calf blood flow decreased 30% during O2 breathing. The decrease in calf blood flow was found to be oxygen dose dependent. A similar magnitude, as for the peripheral circulation, of the effect on central parameters (HR/CO and SVR) and in the time relationship was noted. Hyperoxia did not change O2. An average of 207 (93) mL O2 per subject was washed in during the experiments.Conclusion: This model appears suitable for the investigation of O2-related effects on the central and peripheral circulation in man. Our findings, based on a more comprehensive (central/peripheral circulation examination) evaluation than earlier made, suggest significant circulatory effects of hyperoxia. Further studies are warranted to elucidate the underlying mechanisms.
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| 5. |
- Sjöberg, Birthe, et al.
(författare)
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Hermiones förvandling
- 2009
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Ingår i: Kulturhjälten : Viktor Rydbergs humanism. - 9789173533126
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Texten behandlar hur Strindberg använt sig av Rydbergs karaktär Hermione i Den siste athenaren när han skrev sitt drama "Hermione".
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| 6. |
- Bak, Zoltan, 1950-
(författare)
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Cardiovascular response to hyperoxemia, hemodilution and burns : a clinical and experimental study
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The last decades less invasive monitoring and analytical tools have been developed for the evaluation of myocardial mechanics in clinical praxis. In critical care, these are longed-for complements to pulmonary artery catheter monitoring, additionally offering previously inaccessible information. This work is aimed, during fluid-replacement and oxygen therapy, to determine the physiological interface of ventricular and vascular mechanical properties, which result in the transfer of blood from the heart to appropriate circulatory beds. In prospective clinical studies we investigated previously cardiovascular healthy adults during hyperoxemia, and during preoperative acute normovolemic hemodilution or early fluid resuscitation of severe burn victims. Echocardiography was used in all studies, transthoracic for healthy volunteers and transesophageal for patients. For vascular parameters and for control purposes pulmonary artery Swan-Ganz catheter, calibrated external pulse recordings, whole body impedance cardiography, and transpulmonel thermodilution method were applied.We detected no significant change in blood pressure or heart rate, the two most often used parameters for patient monitoring. During preoperative acute normovolemic hemodilution a reduction of hemoglobin to 80 g/l did not compromise systolic or diastolic myocardial function. Cardiac volumes and flow increased with a concomitant fall in systemic vascular resistance while oxygen delivery seemed maintained. Supplemental oxygen therapy resulted in a linear dose-response between arterial oxygen and cardiovascular parameters, suggesting a direct vascular effect. Cardiac flow decreased and vascular resistance increased from hyperoxemia, and a decrease of venous return implied extracardial blood-pooling. Severe burns result in hypovolemic shock if not properly treated. The commonly used Parkland fluid replacement strategy, with urinary output and mean arterial pressure as endpoints, has recently been questioned. Applying this strategy, only transient early central hypovolemia was recorded, while dimensional preload, global left ventricular systolic function and oxygen delivery or consumption remained within normal ranges during the first 36 hours after accident. Signs of restrictive left ventricular diastolic function were detected in all patients and regional unstable systolic dysfunction was recognized in every other patient, and was consistent with myocardial marker leakage. Severe burns thereby cause myocardial stiffness and systolic regional dysfunction, which may not be prevented only by central normovolemia and adequate oxygenation.
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