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- 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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| 2. |
- Liffner, G, et al.
(författare)
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Inhalation injury assessed by score does not contribute to the development of acute respiratory distress syndrome in burn victims
- 2005
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Ingår i: Burns. - : Elsevier BV. - 0305-4179 .- 1879-1409. ; 31:3, s. 263-268
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To establish the incidence, mortality, and time of onset of acute respiratory distress syndrome (ARDS) in relation to extent of burn and inhalation injury in patients who required mechanical ventilation. Design: Data about burn and inhalation injury were recorded prospectively whereas ARDS and multiple organ dysfunction were assessed by review of patient charts. Setting: National burn intensive care unit at Linköping University Hospital, Sweden (a tertiary referral hospital). Patients: Between 1993 and 1999, we studied all patients with thermal injury (n = 553) who required mechanical ventilation for more than two days (n = 91). Measurements and results: Out of the thirty-six burn victims who developed ARDS (40%), 25 (70%) did so early post burn (in less than 6 days). Patients with ARDS had higher multiple organ dysfunction scores (mean 10.5) than those who did not develop ARDS (mean 5.6) (p < 0.01). The probable presence of inhalation injury as assessed by an inhalation lung injury score (ILIS) did not contribute to the development of ARDS. Mortality tended to be higher in patients who developed ARDS (14%) compared to those who did not (6%, p = 0.2). Conclusions: In our burn patients the incidence of ARDS was high whereas mortality was low. We found no association between inhalation injury as assessed using the ILIS and development of ARDS. Our data support a multi-factorial origin of ARDS in burn victims as a part of a multiple organ failure event. © 2004 Elsevier Ltd and ISBI. All rights reserved.
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| 3. |
- Nilsson, Andreas, et al.
(författare)
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Patient controlled sedation using a standard protocol for dressing changes in burns : Patients' preference, procedural details and a preliminary safety evaluation
- 2008
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Ingår i: Burns. - : Elsevier BV. - 0305-4179 .- 1879-1409. ; 34:7, s. 929-934
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patient controlled sedation (PCS) enables patients to titrate doses of drugs by themselves during different procedures involving pain or discomfort. Methods: We studied it in a prospective crossover design using a fixed protocol without lockout time to examine it as an alternative method of sedation for changing dressings in burned patients. Eleven patients with >10% total burn surface area (TBSA) had their dressings changed, starting with sedation by an anaesthetist (ACS). The second dressing change was done with PCS (propofol/alfentanil) and the third time the patients had to choose ACS or PCS. During the procedures, data on cardiopulmonary variables, sedation (bispectral index), pain intensity (VAS), procedural details, doses of drugs, and patients' preferences were collected to compare the two sedation techniques. Results: The study data indicated that wound care in burned patients is feasible with a standardized PCS protocol. The patients preferred PCS to ACS on the basis of self-control, and because they had less discomfort during the recovery period. Wound care was also considered adequate by the staff during PCS. No respiratory (respiratory rate/transcutaneous PCO2) or cardiovascular (heart rate/blood pressure) adverse events were recorded at any time during any of the PCS procedures. The doses of propofol and alfentanil and BIS index decrease were less during PCS than ACS. Procedural pain was higher during PCS but lower after the procedure. Conclusion: We suggest that PCS using a standard protocol is an interesting alternative to anaesthetist-provided sedation during dressing changes. It seems effective, saves resources, is safe, and at same time is preferred by the patients. The strength of these conclusions is, however, hampered by the small size of this investigation and therefore further studies are warranted. © 2008 Elsevier Ltd and ISBI.
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| 4. |
- Reske, A, et al.
(författare)
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Computed tomography - A possible aid in the diagnosis of smoke inhalation injury?
- 2005
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 49:2, s. 257-260
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Tidskriftsartikel (refereegranskat)abstract
- Inhalation injury is an important contributor to morbidity and mortality in burn victims and can trigger acute lung injury and acute respiratory distress syndrome (ARDS) (1-3). Early diagnosis and treatment of inhalation injury are important, but a major problem in planning treatment and evaluating the prognosis has been the lack of consensus about diagnostic criteria (4). Chest radiographs on admission are often non-specific (5, 6), but indicators include indoor fires, facial burns, bronchoscopic findings of soot in the airways, and detection of carbon monoxide or cyanide in the blood (7). Changes in the lungs may be detected by bronchoscopy with biopsy, xenon imaging, or measurement of pulmonary extracellular fluid (4, 5, 8). These methods have, however, been associated with low sensitivity and specificity, as exemplified by the 50% predictive value in the study of Masanes et al. (8). Computed tomographs (CTs) are better than normal chest radiographs in the detection of other pulmonary lesions such as pulmonary contusion (9, 10). The importance of CT scans in patients with ARDS has been reviewed recently (9), but unfortunately there has been no experience of CT in patients with smoke inhalation injury. To our knowledge, there are only two animal studies reporting that smoke inhalation injury can be detected by CT (4, 11), specific changes in human CT scans have not yet been described. Therefore, confronted with a patient with severe respiratory failure after a burn who from the history and physical examination showed the classic risk factors for inhalation injury, we decided to request a CT. © Acta Anaesthesiologica Scandinavica 49 (2005).
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| 5. |
- 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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| 6. |
- Steinvall, Ingrid, 1959-, et al.
(författare)
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Acute respiratory distress syndrome is as important as inhalation injury for the development of respiratory dysfunction in major burns
- 2008
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Ingår i: Burns. - : Elsevier BV. - 0305-4179 .- 1879-1409. ; 34:4, s. 441-451
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Tidskriftsartikel (refereegranskat)abstract
- Respiratory dysfunction is common after major burns. The pathogenesis is, however, still under debate. The aim was to classify and examine underlying reasons for respiratory dysfunction after major burns. Consecutive adult patients (n = 16) with a total burned body surface area of 20% or more who required mechanical ventilation were assessed for acute respiratory distress syndrome (ARDS), inhalation injury, sepsis, ventilator-associated pneumonia (VAP), ventilator-induced lung injury (VILI), using conventional criteria, together with measurements of cardiovascular variables and viscoelastic properties of the lung including extravascular lung water. Nine patients developed ARDS within 6 days of injury. ARDS was characterized by a large reduction in the PEEP-adjusted PaO2:FiO2 ratio, pulmonary compliance, and increased extra vascular lung water together with increased renal dysfunction rates. Seven patients fulfilled the criteria for inhalation injury. They also had decreased PaO2:FiO2 ratios. There was an increase in extra vascular lung water and a decrease in compliance measures though not to the same extent as in the ARDS group. White blood cell counts dropped from (mean) 21.4 x 10exp9 /l (95% CI 15.3-27.5) in day 1 to 4.3 x 10exp9 /l (2.2-6.5) on day 3, and lower values tended to correlate with the development of ARDS. Sepsis occurred before onset of ARDS in only three cases. One patient fulfilled the criteria for VAP, but none was thought to have VILI. We found that respiratory dysfunction after burns is multifactorial, and ARDS and inhalation injury are most important. The early onset of ARDS, together with the changes in white blood cell count and organ dysfunction, favours a syndrome in which respiratory distress is induced by an inflammatory process mediated by the effect of the burn rather than being secondary to sepsis. The power of these conclusions is, however, hampered by the small number of patients in this study.
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