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Direct noninvasive assessment of brain metabolism during increased intracranial pressure: Potential therapeutic vistas
158
ABSTRACTS
the fat embolism syndrome and isolated arterial hypoxemia was studied in 42 controls and 40 steroid-treated subjects. Fat embolism occurred in ten controls (23.8%) and one steroidtreated subject (2.5%) (p = 0.01). A further 44 subjects developed isolated hypoxemia. This was severe (PaO, < 50 mm Hg) in seven of 32 controls (21.9%) and one of 39 steroid-treated subjects (2.6%) (p = 0.01). The overall incidence of hypoxemia was 67.1%, affecting 33 controls (78.6%) and 22 steroid-treated patients (55%) (p < 0.05). The degree of hypoxemia was severe (PaO, < 50 mm Hg) in 12 controls (28.6%) and two (5%) of the steroid-treated subjects (p = 0.005). No control subject died or required mechanical ventilation. One steroid-treated subject without fat embolism died of a fulminant infection. Although methylprednisolone in a relatively low dose provides protection against fat embolism and pulmonary dysfunction after skeletal trauma, the safety of this therapy requires further evaluation. (Reprinted with permission.) The With drome.
Early Biochemical and Hormonal Profile of Patients Long Bone Fractures at Risk of Fat Embolism Syn-
Schnaid
E. Lamprey
JM.
Viljoen
MJ,
et al.
J
Trauma 27:309, 1987. Free fatty acids (FFA) are believed to play a role in the genesis of the fat embolism syndrome (FES). Levels of plasma FFA, glucose, insulin, and the stress hormones cortisol, growth hormone, prolactin, glucagon, and catecholamines were measured on admission to hospital in: a) 14 patients with long bone fractures at risk of developing FES, b) 14 patients with soft-tissue injuries of comparable severity, and c) 20 healthy fasting subjects. The findings were similar in both groups of injured patients and in keeping with the hormonal and substrate responses to the stress of trauma; plasma FFA levels were raised but in neither group was the rise pronounced. Plasma FFA levels of the fracture patients were only moderately higher than the values of the healthy fasting subjects. These findings suggest that mobilized FFA from peripheral adipose tissue are not important in the genesis of the FES, but do not exclude a role for FFA derived mainly from hydrolysis of triglyceride emboli in the lung. (Reprinted with permission.) Direct
Noninvasive
Assessment
of Brain
Metabolism
Increased Intracranial Pressure: Potential Therapeutic tas. Cairns CB, Fillip0 D. Palladino GW, et al. J
During Vis-
Trauma
26:863, 1986. Intracranial pressure was increased in cats by infusing ‘mock’ CSF intracranially, thus decreasing cerebral perfusion and oxygenation. The cats then randomly received either 50% O2 or 50% 01-5% CO1 by inhalation. As monitored by in vivo near-infrared spectroscopy (NIR), no improvement was noted after 50% O2 whereas 50% O,-5% CO2 resulted in increased perfusion, an oxidation of cytochrome a,a,, an increase in oxyhemoglobin, and reduced quantities of deoxyhemoglobin (p < 0.01) despite a further increase in intracranial pressure. The authors conclude that: a) NIR is a useful means of noninvasively and directly assessing brain metabolism and has advantages over simple ICP monitoring; and b) continued investigations of CO* as a possible thera-
peutic modality after head injury appear warranted. (Reprinted with permission.) Continuous ment
for
Arteriovenous Surgical
RE, Lees P,
Acute
Filtration: Renal
Failure.
An
Effective
Mault
Treat-
JR, Dechert
et al. Surgery 101:478, 1987.
Continuous arteriovenous hemofiltration (CAVH) is a new method of renal replacement therapy that has several advantages in the surgical treatment of acute renal failure. We initially learned the technique in laboratory testing and then developed a management protocol. Since 1983 we have used CAVH to treat 61 patients with acute renal failure. This extracorporeal technique consists of arteriovenous cannulation of the femoral vessels,which provides continuous blood flow through a hollow-fiber membrane. Hydrostatic pressure (systole greater than 80 mm Hg) creates an ultrafiltrate at a typical rate of 12 L/day. Volume is replaced with an intravenous solution at a rate to achieve the desired fluid balance, usually a net loss of 1 to 2 L/day. This extracellular fluid exchange typically results in removal of 15 gm of urea nitrogen and 50 mEq of potassium per day. The technique can be used in most intensive care units and has relatively few complications. In addition to being a safe and effective means of renal replacement therapy for acute renal failure, CAVH is particularly advantageous for managing conditions of fluid overload in hemodynamically unstable patients. (Reprinted with permission.) Naloxone in Renal Ischemie: A Functional and tomical Study. Elkadi HK, Nghiem DD, Southard
Microana-
JH, et al.
J Surg Res 42:675, 1987. Naloxone HCI (Nx) improves cardiopulmonary performance, reverses cellular hypoxia, and stabilizes lysosomal membranes in shock states. However, no detailed study has yet explored its potential role in renal ischemia, which is inevitable in transplantation and surgical and nonsurgical conditions associated with hypotension and shock. This functional and microanatomical study was carried out on dogs subjects to renal warm ischemia with contralateral nephrectomy. Group I (control; N = 4) had bilateral renal dissection and right nephrectomy. Groups II-IV had their kidney pedicles cross-clamped for 60 min and then reperfused. Group II (N = 9) ischemic kidneys received no treatment. Group III (N = 6) kidneys were flushed with pure Nx HCI (2 mg/kg) during ischemia. Group IV (N = 6) dogs received one iv Nx bolus (2 mg/kg) before clamping and another dose before declamping. Biopsies for adenine nucleotides, histology, and ultrastructure were obtained before &hernia, before reflow, and 15 min and 7 days after reflow. Serum creatinine and blood urea nitrogen were measured daily. Ischemia induced significant renal dysfunction, which was reversed by systemic Nx. Nx offered a remarkable protection against postischemic structural damage. Seventy percent of Group II cortical sections showed grade 4 acute tubular necrosis (ATN), and severe residual damage after a week. Eighty-three percent of Group IV sections showed grade 1 ATN and no residual damage after a week. One week survival was 33% in Group II and 100% in Group IV. Nx can be useful in prevention of acute renal failure in clinical situations with arterial hypotension and shock. (Reprinted with permission.)
ABSTRACTS
the fat embolism syndrome and isolated arterial hypoxemia was studied in 42 controls and 40 steroid-treated subjects. Fat embolism occurred in ten controls (23.8%) and one steroidtreated subject (2.5%) (p = 0.01). A further 44 subjects developed isolated hypoxemia. This was severe (PaO, < 50 mm Hg) in seven of 32 controls (21.9%) and one of 39 steroid-treated subjects (2.6%) (p = 0.01). The overall incidence of hypoxemia was 67.1%, affecting 33 controls (78.6%) and 22 steroid-treated patients (55%) (p < 0.05). The degree of hypoxemia was severe (PaO, < 50 mm Hg) in 12 controls (28.6%) and two (5%) of the steroid-treated subjects (p = 0.005). No control subject died or required mechanical ventilation. One steroid-treated subject without fat embolism died of a fulminant infection. Although methylprednisolone in a relatively low dose provides protection against fat embolism and pulmonary dysfunction after skeletal trauma, the safety of this therapy requires further evaluation. (Reprinted with permission.) The With drome.
Early Biochemical and Hormonal Profile of Patients Long Bone Fractures at Risk of Fat Embolism Syn-
Schnaid
E. Lamprey
JM.
Viljoen
MJ,
et al.
J
Trauma 27:309, 1987. Free fatty acids (FFA) are believed to play a role in the genesis of the fat embolism syndrome (FES). Levels of plasma FFA, glucose, insulin, and the stress hormones cortisol, growth hormone, prolactin, glucagon, and catecholamines were measured on admission to hospital in: a) 14 patients with long bone fractures at risk of developing FES, b) 14 patients with soft-tissue injuries of comparable severity, and c) 20 healthy fasting subjects. The findings were similar in both groups of injured patients and in keeping with the hormonal and substrate responses to the stress of trauma; plasma FFA levels were raised but in neither group was the rise pronounced. Plasma FFA levels of the fracture patients were only moderately higher than the values of the healthy fasting subjects. These findings suggest that mobilized FFA from peripheral adipose tissue are not important in the genesis of the FES, but do not exclude a role for FFA derived mainly from hydrolysis of triglyceride emboli in the lung. (Reprinted with permission.) Direct
Noninvasive
Assessment
of Brain
Metabolism
Increased Intracranial Pressure: Potential Therapeutic tas. Cairns CB, Fillip0 D. Palladino GW, et al. J
During Vis-
Trauma
26:863, 1986. Intracranial pressure was increased in cats by infusing ‘mock’ CSF intracranially, thus decreasing cerebral perfusion and oxygenation. The cats then randomly received either 50% O2 or 50% 01-5% CO1 by inhalation. As monitored by in vivo near-infrared spectroscopy (NIR), no improvement was noted after 50% O2 whereas 50% O,-5% CO2 resulted in increased perfusion, an oxidation of cytochrome a,a,, an increase in oxyhemoglobin, and reduced quantities of deoxyhemoglobin (p < 0.01) despite a further increase in intracranial pressure. The authors conclude that: a) NIR is a useful means of noninvasively and directly assessing brain metabolism and has advantages over simple ICP monitoring; and b) continued investigations of CO* as a possible thera-
peutic modality after head injury appear warranted. (Reprinted with permission.) Continuous ment
for
Arteriovenous Surgical
RE, Lees P,
Acute
Filtration: Renal
Failure.
An
Effective
Mault
Treat-
JR, Dechert
et al. Surgery 101:478, 1987.
Continuous arteriovenous hemofiltration (CAVH) is a new method of renal replacement therapy that has several advantages in the surgical treatment of acute renal failure. We initially learned the technique in laboratory testing and then developed a management protocol. Since 1983 we have used CAVH to treat 61 patients with acute renal failure. This extracorporeal technique consists of arteriovenous cannulation of the femoral vessels,which provides continuous blood flow through a hollow-fiber membrane. Hydrostatic pressure (systole greater than 80 mm Hg) creates an ultrafiltrate at a typical rate of 12 L/day. Volume is replaced with an intravenous solution at a rate to achieve the desired fluid balance, usually a net loss of 1 to 2 L/day. This extracellular fluid exchange typically results in removal of 15 gm of urea nitrogen and 50 mEq of potassium per day. The technique can be used in most intensive care units and has relatively few complications. In addition to being a safe and effective means of renal replacement therapy for acute renal failure, CAVH is particularly advantageous for managing conditions of fluid overload in hemodynamically unstable patients. (Reprinted with permission.) Naloxone in Renal Ischemie: A Functional and tomical Study. Elkadi HK, Nghiem DD, Southard
Microana-
JH, et al.
J Surg Res 42:675, 1987. Naloxone HCI (Nx) improves cardiopulmonary performance, reverses cellular hypoxia, and stabilizes lysosomal membranes in shock states. However, no detailed study has yet explored its potential role in renal ischemia, which is inevitable in transplantation and surgical and nonsurgical conditions associated with hypotension and shock. This functional and microanatomical study was carried out on dogs subjects to renal warm ischemia with contralateral nephrectomy. Group I (control; N = 4) had bilateral renal dissection and right nephrectomy. Groups II-IV had their kidney pedicles cross-clamped for 60 min and then reperfused. Group II (N = 9) ischemic kidneys received no treatment. Group III (N = 6) kidneys were flushed with pure Nx HCI (2 mg/kg) during ischemia. Group IV (N = 6) dogs received one iv Nx bolus (2 mg/kg) before clamping and another dose before declamping. Biopsies for adenine nucleotides, histology, and ultrastructure were obtained before &hernia, before reflow, and 15 min and 7 days after reflow. Serum creatinine and blood urea nitrogen were measured daily. Ischemia induced significant renal dysfunction, which was reversed by systemic Nx. Nx offered a remarkable protection against postischemic structural damage. Seventy percent of Group II cortical sections showed grade 4 acute tubular necrosis (ATN), and severe residual damage after a week. Eighty-three percent of Group IV sections showed grade 1 ATN and no residual damage after a week. One week survival was 33% in Group II and 100% in Group IV. Nx can be useful in prevention of acute renal failure in clinical situations with arterial hypotension and shock. (Reprinted with permission.)