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Turning to the past
THE LANCET
Turning to the past J Dean Sandham
The stock-in-trade of critical care is the physiological currently being assessed in clinical trials (Kelly). Due to support of patients with failing organs. The critical-care their greater density, PFC accumulate in dependent lung literature reflects thiswith a prominent focus on support where they may physically expand atelectatic lung (acting of the injured lung. Two interesting areas of developing like liquid positive end-expiratory pressure), provide understanding are use of the prone position for ventilation surface-tension reducing properties, or displace blood flow to less dependent lung areas. By floating and use of partial liquid ventilation (PLV). Dramatic improvement in aqueous substances and lung oxygenation in patients inflammatory debris to the with adult respiratory distress surface for removal, the syndrome (ARDS) who were inflammatory process may be cared for in the prone decreased. position was first observed in Because improved the 1970s. General use of the physiological support technique has not been has prolonged patients' intensive-care-unit (ICU) adopted (Webster). In the survival, we face the largest single series of cases reported to date (Chatte), a overwhelming "mediator storm" precipitated by injury positive response (defined as or infection. This systemic increases in the PaO2/FiO 2 inflammatory response ratio by >20 mm Hg within syndrome, mediated by 1 h of turning) was found in macrophage-derived 78% of 30 optimally ventilated patients. In 57% of cytokines that target endresponders, the improvement organ receptors in response to injury or infection, causes in gas exchange persisted for further dysfunction or failure the study duration (4 h). This of vital organ systems. improvement may be due to Attempts to modulate modification of the wellthis response with known mismatch of ventilation and perfusion that non-glucocorticoid antiinflammatory agents (such as occurs in ARDS associated monoclonal antibody to with dependent water in the Chest radiograph of a patient being ventilated with PFC tumour necrosis factor) have lung, caudal movement of the been the object of intense dorsal diaphragm (much less interest. A systematic review (Zeni) of 18 clinical trials of mobile in the supine position), or a more homogeneous six of these agents and nine clinical trials of distribution of ventilation in the prone position. At least glucocorticoids in management of sepsis and septic shock three experienced staff members are required to perform assessed 6429 patients. When pooled, the patient data prone-positioning turns safely while protecting the airway showed a small beneficial treatment effect that was not and intravenous catheters. Studies are small and statistically significant (OR 1:11; CI 0.99-1.23; p=0.07). physiological endpoints (changes in blood oxygenation) Given the complexity and multiplicity of the mediators of are used as surrogates for more important outcomes systemic inflammatory response, the development of the (changes in morbidity or mortality). potential of this therapy is an exciting challenge. Perfluorocarbons (PFC) are clear liquids more dense than water with a much greater solubility for oxygen and carbon dioxide. They have been shown to allow liquid Key references for 1997 ventilation of the lungs of both mechanically ventilated Bartlett R, C r e t e M, H c r s c h l R, et al. A phase II r a n d o m i z e d and spontaneously breathing animals. Total liquid controlled trial o f partial liquid ventilation (PLV) i n adult ventilation requires complex ventilators. The concept of patients w i t h a c u t e h y p o x e m i c respiratory failure ( A H R F ) . Crit partially fillings lungs with PFC to functional residual Care M e d 1997; 25: No 2 (suppl). capacity and then ventilating with a standard gas operated Chatte G, S a b J, D n b o i s J, et al. P r o n e position in m e c h a n i c a l l y ventilated patients w i t h severe a c u t e respiratory f a i l u r e . . 4 m J ventilator (partial liquid ventilation [PLV]) has allowed Respir Crit Care M e d 1997; 155: 473-78. early clinical application in a small series of paediatric Kelly K. P a r t i a l H q u i d v e n t i l a t i o n - - t u r n i n g b a c k a P A G E on (N Engl J Med 1996; 335: 761) and adult patients evolution. B r J A n a e s t h 1997; 78: 1-2. (Bartlett). One of these substances, Perflubron, is Webster N. Ventilation in the prone p o s i t i o n . L a n c e t 1997; 349: Lancet 1997; 350 (suppl III): 3 Foothills Hospital, Calgary, AB T2N 2T9, Canada (J D Sandham MD)
End O f Year Review ° 1997
1638-39. Z e n i F, F r e e m a n B , N a t a n s o n C. A n t i - i n f l a m m a t o r y therapies to treat sepsis and septic shock: a r e a s s e s s m e n t . Crit Care M e d 1997; 25: 1095-100.
SIII3
Turning to the past J Dean Sandham
The stock-in-trade of critical care is the physiological currently being assessed in clinical trials (Kelly). Due to support of patients with failing organs. The critical-care their greater density, PFC accumulate in dependent lung literature reflects thiswith a prominent focus on support where they may physically expand atelectatic lung (acting of the injured lung. Two interesting areas of developing like liquid positive end-expiratory pressure), provide understanding are use of the prone position for ventilation surface-tension reducing properties, or displace blood flow to less dependent lung areas. By floating and use of partial liquid ventilation (PLV). Dramatic improvement in aqueous substances and lung oxygenation in patients inflammatory debris to the with adult respiratory distress surface for removal, the syndrome (ARDS) who were inflammatory process may be cared for in the prone decreased. position was first observed in Because improved the 1970s. General use of the physiological support technique has not been has prolonged patients' intensive-care-unit (ICU) adopted (Webster). In the survival, we face the largest single series of cases reported to date (Chatte), a overwhelming "mediator storm" precipitated by injury positive response (defined as or infection. This systemic increases in the PaO2/FiO 2 inflammatory response ratio by >20 mm Hg within syndrome, mediated by 1 h of turning) was found in macrophage-derived 78% of 30 optimally ventilated patients. In 57% of cytokines that target endresponders, the improvement organ receptors in response to injury or infection, causes in gas exchange persisted for further dysfunction or failure the study duration (4 h). This of vital organ systems. improvement may be due to Attempts to modulate modification of the wellthis response with known mismatch of ventilation and perfusion that non-glucocorticoid antiinflammatory agents (such as occurs in ARDS associated monoclonal antibody to with dependent water in the Chest radiograph of a patient being ventilated with PFC tumour necrosis factor) have lung, caudal movement of the been the object of intense dorsal diaphragm (much less interest. A systematic review (Zeni) of 18 clinical trials of mobile in the supine position), or a more homogeneous six of these agents and nine clinical trials of distribution of ventilation in the prone position. At least glucocorticoids in management of sepsis and septic shock three experienced staff members are required to perform assessed 6429 patients. When pooled, the patient data prone-positioning turns safely while protecting the airway showed a small beneficial treatment effect that was not and intravenous catheters. Studies are small and statistically significant (OR 1:11; CI 0.99-1.23; p=0.07). physiological endpoints (changes in blood oxygenation) Given the complexity and multiplicity of the mediators of are used as surrogates for more important outcomes systemic inflammatory response, the development of the (changes in morbidity or mortality). potential of this therapy is an exciting challenge. Perfluorocarbons (PFC) are clear liquids more dense than water with a much greater solubility for oxygen and carbon dioxide. They have been shown to allow liquid Key references for 1997 ventilation of the lungs of both mechanically ventilated Bartlett R, C r e t e M, H c r s c h l R, et al. A phase II r a n d o m i z e d and spontaneously breathing animals. Total liquid controlled trial o f partial liquid ventilation (PLV) i n adult ventilation requires complex ventilators. The concept of patients w i t h a c u t e h y p o x e m i c respiratory failure ( A H R F ) . Crit partially fillings lungs with PFC to functional residual Care M e d 1997; 25: No 2 (suppl). capacity and then ventilating with a standard gas operated Chatte G, S a b J, D n b o i s J, et al. P r o n e position in m e c h a n i c a l l y ventilated patients w i t h severe a c u t e respiratory f a i l u r e . . 4 m J ventilator (partial liquid ventilation [PLV]) has allowed Respir Crit Care M e d 1997; 155: 473-78. early clinical application in a small series of paediatric Kelly K. P a r t i a l H q u i d v e n t i l a t i o n - - t u r n i n g b a c k a P A G E on (N Engl J Med 1996; 335: 761) and adult patients evolution. B r J A n a e s t h 1997; 78: 1-2. (Bartlett). One of these substances, Perflubron, is Webster N. Ventilation in the prone p o s i t i o n . L a n c e t 1997; 349: Lancet 1997; 350 (suppl III): 3 Foothills Hospital, Calgary, AB T2N 2T9, Canada (J D Sandham MD)
End O f Year Review ° 1997
1638-39. Z e n i F, F r e e m a n B , N a t a n s o n C. A n t i - i n f l a m m a t o r y therapies to treat sepsis and septic shock: a r e a s s e s s m e n t . Crit Care M e d 1997; 25: 1095-100.
SIII3