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Atrial natriuretic peptide decrease during spontaneous breathing with continuous positive airway pressure in volume-expanded healthy volunteers
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Newman LS, Szczukowski LC, Bain RP, et Suppurative mediastinitis after open heart surgery. Chest 94:546-553, 1988 ah
Unlike previously reported series on poststernotomy suppurative mediastinitis (PSSM), which failed to use careful case-control methodology and case definitions, this retrospective case-control study evaluated the incidence of and risk factors associated with PSSM over a 10-year period in 9965 patients. Case controls were two patients per PSSM case, matched for age, sex, and date of surgery. However, case selection, missing data, and inability to validate information on the medical record inherently limit study methodology. PSSM, defined as frankly purulent retrosternal material or positive retrosternal wound cultures after median sternotomy, occurred in 0.7% of patients. Factors associated with PSSM included increased left ventricular end diastolic pressure, low ejection fraction, pyuria, history of previous sternotomy, and chronic obstructive lung disease. Prolonged duration of cardiopulmonary bypass and surgery (4.12 v 3.44 hours) was associated with an increased incidence of PSSM, as were valvular or aortic aneurysm surgery. Prolonged mechanical ventilation, postoperative hemorrhage requiring reexploration, and postoperative cardiopulmonary resuscitation increased the occurrence of PSSM. Neither diabetes nor tracheostomy increased the risk of PSSM. Multivariate analysis of the previously listed factors confirmed that the duration of surgery was associated most strongly with mediastinitis. Other independent risk factors were history of chronic obstructive pulmonary disease and duration of mechanical ventilation.
Kingma JG, Rouleau JR, Magrina J, et ah Effects of perfluorochemical hemodilution on coronary blood flow distribution in dogs. Circulation 78:746-753, 1988 Perfluorocarbons (PFC) may benefit myocardial blood flow and oxygenation by increased diffusion of oxygen from the PFC into the tissue due to small particle size or because of reduced affinity of blood-PFC mixture for oxygen. Circumflex coronary artery pressure/flow relations were determined during maximal vasodilatation before and after hemodilution with 1 L of intravenous (IV) PFC given at 25 mL/min. Before PFC, the lower pressure limit (LPL) of pressure/flow autoregulation was 55 _+ 9 mmHg. LPL decreased to 39 _+ 10 mmHg after hemodilution. Endocardial blood flow and the endo/epi flow ratio increased with PFC hemodilution. Thus, coronary blood flow distribution distal to a stenosis was maintained with PFC due to an increased capability of the endocardial vessels to autoregulate and due to increased tissue oxygen delivery during PFC. With oxygen supplementation, oxygen transport increased significantly even with coronary perfusion pressures below the LPL. However, PFC that do not cause adverse effects such as hypotension, pulmonary insufficiency, complement activation, and reticuloendothelial system blockade must be developed before the benefits of improved coronary blood flow and oxygen transport in the endocardium can be applied to humans with myocardial ischemia.
CAROL L. LAKE
Norwood SH, Cormier B, McMahon NG, et Prospective study of catheter-related infection during prolonged arterial catheterization. C r i t Care Med 16:836-839, 1988 ah
Ninety-six arterial catheters from 75 anatomic sites (62 radial, four femoral, and nine axillary) in 56 patients were prospectively studied for catheter-related infection. The protocol for catheter care included replacement of the flush solution every 24 hours, replacement of the transducer-tubing system every 48 hours, replacement of sterile occlusive gauze dressing every 24 hours, and blood sampling via 22-gauge T-connector rubber hub after cleansing with povidone-iodine and alcohol. Catheters were replaced every 96 hours using sterile Seldinger technique if cultures remained negative. Semiquantitative cultures of the removed catheters and swab culturing of the skin insertion site were performed every 96 hours. No skin sites used less than 96 hours had positive cultures, while 21% of sites used longer than 96 hours were culture-positive. No catheters had positive cultures if the skin site cultures were negative. However, 57% of skin sites with positive cultures also had positive catheter cultures. Infection rates were significantly higher for the axillary site. Although not specifically studied, the authors suggest that control of skin site colonization is important for prolonged cannulation without infectious complications.
Frass M, Popovic R, Hartter E, et ah Atrial natriuretic peptide decrease during spontaneous breathing with continuous positive a i r w a y p r e s s u r e in volume-expanded healthy volunteers. Crit Care Med 16:831-835, 1988 In addition to decreased renal blood flow, alteration of intrarenal blood flow distribution, increased antidiuretic hormone, and increased renal venous pressure, decreased atrial natriuretic peptide (ANP) may enhance the fluid retention and renal dysfunction during continuous positive airway pressure (CPAP). In 11 healthy volunteers, volume loaded with Ringer's lactate fluid at 13 mL/kg/hr for two hours before and during CPAP, ANP decreased significantly at 20 cm H20. Volume loading without CPAP increased ANP. Plasma renin activity, angiotensin II, cortisol, and aldosterone decreased during volume loading but were unchanged by the addition of CPAP. Norepinephrine and epinephrine were unaffected by either volume loading or CPAP. A probable mechanism for the decreased ANP is atrial compression by distended lungs and reduced venous return.
Sniderman AD, Fitchett DH: Vasodilators and pulmonary arterial hypertension: The paradox of therapeutic success and clinical failure. Int J Cardiol 20:173-181, 1988 Pathologic pulmonary vasoconstriction not only causes pulmonary hypertension but also increases the hydraulic load on the right ventricle. This editorial reviews the factors to be considered in accurate measurements of pulmonary tone and the effects of the pulmonary circulation
Newman LS, Szczukowski LC, Bain RP, et Suppurative mediastinitis after open heart surgery. Chest 94:546-553, 1988 ah
Unlike previously reported series on poststernotomy suppurative mediastinitis (PSSM), which failed to use careful case-control methodology and case definitions, this retrospective case-control study evaluated the incidence of and risk factors associated with PSSM over a 10-year period in 9965 patients. Case controls were two patients per PSSM case, matched for age, sex, and date of surgery. However, case selection, missing data, and inability to validate information on the medical record inherently limit study methodology. PSSM, defined as frankly purulent retrosternal material or positive retrosternal wound cultures after median sternotomy, occurred in 0.7% of patients. Factors associated with PSSM included increased left ventricular end diastolic pressure, low ejection fraction, pyuria, history of previous sternotomy, and chronic obstructive lung disease. Prolonged duration of cardiopulmonary bypass and surgery (4.12 v 3.44 hours) was associated with an increased incidence of PSSM, as were valvular or aortic aneurysm surgery. Prolonged mechanical ventilation, postoperative hemorrhage requiring reexploration, and postoperative cardiopulmonary resuscitation increased the occurrence of PSSM. Neither diabetes nor tracheostomy increased the risk of PSSM. Multivariate analysis of the previously listed factors confirmed that the duration of surgery was associated most strongly with mediastinitis. Other independent risk factors were history of chronic obstructive pulmonary disease and duration of mechanical ventilation.
Kingma JG, Rouleau JR, Magrina J, et ah Effects of perfluorochemical hemodilution on coronary blood flow distribution in dogs. Circulation 78:746-753, 1988 Perfluorocarbons (PFC) may benefit myocardial blood flow and oxygenation by increased diffusion of oxygen from the PFC into the tissue due to small particle size or because of reduced affinity of blood-PFC mixture for oxygen. Circumflex coronary artery pressure/flow relations were determined during maximal vasodilatation before and after hemodilution with 1 L of intravenous (IV) PFC given at 25 mL/min. Before PFC, the lower pressure limit (LPL) of pressure/flow autoregulation was 55 _+ 9 mmHg. LPL decreased to 39 _+ 10 mmHg after hemodilution. Endocardial blood flow and the endo/epi flow ratio increased with PFC hemodilution. Thus, coronary blood flow distribution distal to a stenosis was maintained with PFC due to an increased capability of the endocardial vessels to autoregulate and due to increased tissue oxygen delivery during PFC. With oxygen supplementation, oxygen transport increased significantly even with coronary perfusion pressures below the LPL. However, PFC that do not cause adverse effects such as hypotension, pulmonary insufficiency, complement activation, and reticuloendothelial system blockade must be developed before the benefits of improved coronary blood flow and oxygen transport in the endocardium can be applied to humans with myocardial ischemia.
CAROL L. LAKE
Norwood SH, Cormier B, McMahon NG, et Prospective study of catheter-related infection during prolonged arterial catheterization. C r i t Care Med 16:836-839, 1988 ah
Ninety-six arterial catheters from 75 anatomic sites (62 radial, four femoral, and nine axillary) in 56 patients were prospectively studied for catheter-related infection. The protocol for catheter care included replacement of the flush solution every 24 hours, replacement of the transducer-tubing system every 48 hours, replacement of sterile occlusive gauze dressing every 24 hours, and blood sampling via 22-gauge T-connector rubber hub after cleansing with povidone-iodine and alcohol. Catheters were replaced every 96 hours using sterile Seldinger technique if cultures remained negative. Semiquantitative cultures of the removed catheters and swab culturing of the skin insertion site were performed every 96 hours. No skin sites used less than 96 hours had positive cultures, while 21% of sites used longer than 96 hours were culture-positive. No catheters had positive cultures if the skin site cultures were negative. However, 57% of skin sites with positive cultures also had positive catheter cultures. Infection rates were significantly higher for the axillary site. Although not specifically studied, the authors suggest that control of skin site colonization is important for prolonged cannulation without infectious complications.
Frass M, Popovic R, Hartter E, et ah Atrial natriuretic peptide decrease during spontaneous breathing with continuous positive a i r w a y p r e s s u r e in volume-expanded healthy volunteers. Crit Care Med 16:831-835, 1988 In addition to decreased renal blood flow, alteration of intrarenal blood flow distribution, increased antidiuretic hormone, and increased renal venous pressure, decreased atrial natriuretic peptide (ANP) may enhance the fluid retention and renal dysfunction during continuous positive airway pressure (CPAP). In 11 healthy volunteers, volume loaded with Ringer's lactate fluid at 13 mL/kg/hr for two hours before and during CPAP, ANP decreased significantly at 20 cm H20. Volume loading without CPAP increased ANP. Plasma renin activity, angiotensin II, cortisol, and aldosterone decreased during volume loading but were unchanged by the addition of CPAP. Norepinephrine and epinephrine were unaffected by either volume loading or CPAP. A probable mechanism for the decreased ANP is atrial compression by distended lungs and reduced venous return.
Sniderman AD, Fitchett DH: Vasodilators and pulmonary arterial hypertension: The paradox of therapeutic success and clinical failure. Int J Cardiol 20:173-181, 1988 Pathologic pulmonary vasoconstriction not only causes pulmonary hypertension but also increases the hydraulic load on the right ventricle. This editorial reviews the factors to be considered in accurate measurements of pulmonary tone and the effects of the pulmonary circulation