Combined effects of Inversed Ratio Ventilation (IRV) with positive end-expiratory pressure ventilation (PEEP) on cardiorespiratory function in acute respiratory failure

Combined effects of inversed ratio ventilation (IRV) with positive end-expiratory pressure (PEEP) on cardiorespiratory function were examined in 24 patients with acute respiratory failure. Patients were divided into two groups: the IRV group (n = 12) who showed no significant increase in Pa_{O 2} with a 6cmH₂O of PEEP and PEEP group (n = 12) who were ventilated mechanically with PEEP only at maximum level of 10cmH₂O. In IRV group step-wise prolongation of the I:E ratio from 1:1.9 to 2.6:1 or 4:1 was applied as a Pa_{O 2} was improved and in PEEP group also level of PEEP was increased from 0, 5 to 10cmH₂O after one hour period irrespective of Pa_{O 2}. Inversed ratio ventilation and PEEP increased significantly Pa_{O 2}/Fi _{O 2}, the increase being observed 6hrs (I:E = 2:1) and 2hrs (10cmH₂O) after starting IRV or PEEP. Further improvement of oxygenation was not observed in IRV even if I:E ratio was prolonged up to 2.6:1 or 4:1. These results suggested that combinations of IRV with PEEP were effective and an I:E ratio of 2:1 may be optimal, and IRV is advantageous compared to PEEP, but will take more long time to improve oxygenation than PEEP.(Sari A, Toriumi T, Yamashita S, et al.: Combined effects of inversed ratio ventilation (IRV) with positive end-expiratory pressure ventilation (PEEP) on cardiorespiratory function in acute respiratory failure. J Anesth 5: 105–113, 1991)     

The effect of simvastatin on serum cytokine levels and bone metabolism in postmenopausal subjects: negative correlation between TNF-α and anabolic bone parameters

In this prospective study, we aimed to evaluate the effect of simvastatin on bone metabolism and the correlation between changes in bone turnover parameters and serum cytokine levels. For this purpose, 38 postmenopausal subjects with hypercholesterolemia (>240mg/dl), not on osteoporosis treatment, were studied. Simvastatin was started at a dose of 20mg daily and continued for 3 months. Six patients were excluded from the study during the follow-up period. Pre- and post-treatment samples were analyzed for bone alkaline phosphatase (BAP) and osteocalcin (OCL), as markers of bone formation; for carboxyterminal telopeptide of collagen I (CTX), as a marker of bone resorption; and for interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-) cytokine levels. Total cholesterol level was decreased from 262.1 ± 30.9 to 210.2 ± 35.6mg/dl after simvastatin treatment (P < 0.0001). While no significant change was observed in serum CTX level, BAP and OCL levels were significantly increased (from 120.8 ± 56.6 to 149.5 ± 57.6IU/l [P = 0.008], and from 20.8 ± 12.6 to 34.7 ± 18.4µg/l [P = 0.015], respectively). In the analysis of cytokines, while no significant change was observed in IL-6 levels, the TNF- level was found to be significantly decreased after simvastatin treatment (from 77.9 ± 31.6pg/ml to 23.5 ± 12.6pg/ml [P = 0.021]). Individual changes in TNF- levels showed a moderate negative correlation with the individual changes in BAP and OCL levels (r = –0.550 [P = 0.001], and r = –0.497 [P = 0.004], respectively). In conclusion; 20-mg daily simvastatin treatment for 3 months significantly increased BAP and OCL levels (markers of bone formation) in hypercholesterolemic postmenopausal subjects, without affecting bone resorption. These findings support the idea that simvastatin has an anabolic effect on bone formation. Additionally, the presence of a negative correlation between TNF- levels and the anabolic bone parameters suggests that a cytokine-lowering effect of simvastatin may also be involved in the remodeling process and could exert some additive beneficial effect on bone metabolism.     

Brain lesion size and phase shift as an index of cerebral autoregulation in patients with severe head injury

Summary ¶Background. Whether the phase relationship (phase shift) between cerebral blood flow velocity as assessed by transcranial Doppler ultrasound and blood pressure at 0.1Hz can be used to assess cerebral autoregulation (CA) in patients with severe traumatic brain injury (TBI). Methods. In 33 healthy volunteers (mean age, SD; 37±17 years, range 17–65) middle cerebral artery (MCA) blood velocity (V) was recorded simultaneously with finger blood pressure (BP) over a period of 10 minutes under normocapnic and hypocapnic conditions to generate normative data. In 27 patients with severe TBI (Glasgow Coma scale score 8) serial close in time investigations of cranial computed tomography (CT) scanning and phase shift assessment were performed on days 1, 3, 5, and 8 after trauma. Phase shift in the MCA was compared to brain parenchyma lesion size in the MCA territory on CT scanning. Lesion size was classified into 0, normal; 1, presence of a small lesion (diameter <3cm); 2, presence of a large lesion (>3cm). Findings. Compared to normocapnia, hypocapnia significantly increased phase shift at 0.1Hz from 78±28° to 101±25° (p<0.001). In the TBI patients, 115 comparisons between CT findings and CA results were possible. Phase shift detected a pathological CA in 31 instances, which were more frequent in CT lesion type 2 (19/42) than in group 0 (7/44) and group 1 (5/29). Interpretation. When CA is intended to be assessed by use of phase shift, the hyperventilation setting needs its own reference values. In MCA territories containing a traumatic lesion greater than 3cm in diameter phase shift at 0.1Hz will detect a high frequency (44%) of a disturbed state of CA.Published online July 23, 2003     

Sustained effects of plasma norepinephrine levels on femoral-radial pressure gradient after cardiopulmonary bypass

In order to determine the influence of the sympathetic nervous system upon the femoral-radial artery pressure gradient after cardiopulmonary bypass (CPB), we examined plasma norepinephrine levels in 34 adult male patients undergoing coronary artery bypass grafting. Cardiovascular parameters, including systolic arterial pressure, mean arterial pressure, cardiac index (CI), systemic vascular resistance index (SVRI), pulmonary artery pressure (PAP), hemoglobin (Hb) and peak dP/dt of radial and femoral artery pressures were measured after sternotomy, and immediately after the discontinuation of CPB and 90min after CPB. Plasma norepinephrine levels were measured after sternotomy, after aortic declamping and 90min after CPB.The patients were divided into two groups. Group A consisted of 17 patients whose femoral minus radial systolic pressure difference was 15mmHg or more at 90min after CPB, while Group B consisted of 17 patients with the difference less than 15mmHg. Group A patients had significantly longer time values in the duration of both CPB (Group A 175 ± 10min; Group B 115 ± 12min, P 0.001) and aortic cross clamping (Group A 116 ± 7min, Group B 71 ± 9min, P 0.001).Although there was no significant difference in Hb or PAP of 90min after CPB in Groups A and B, the following values, listed in the order of A to B, were obtained; CI, 2.79 ± 0.10 versus 3.46 ± 0.16l·min^–1·m^–2 (P 0.01); mean radial artery pressure (MRP), 58.7 ± 2.4 versus 65.1 ± 1.8mmHg (P 0.05); peak dP/dt of radial artery pressure, 568 ± 64 versus 1026 ± 61mmHg·sec^–1 (P 0.001); and plasma norepinephrine concentration, 1.81 ± 0.25 versus 0.98 ± 0.10ng·ml^–1 (P 0.01), which were statistically significant.The higher femoral-radial artery pressure gradient after CPB was observed in patients with both a longer CPB time and a higher plasma norepinephrine concentration. These results suggest that a marked constriction of peripheral arteries might have produced a damped transmission of the pressure pulse to the radial artery.(Nakayama R, Goto T, Kukita I, et al.: Sustained effects of plasma norepinephrine levels on femoral-radial pressure gradient after cardiopulmonary bypass. J Anesth 7: 8–15, 1993)     

Spinal neurotoxicity and tolerance after repeated intrathecal administration of YM 872, an AMPA receptor antagonist,in rats

Purpose Although the -amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor antagonist, YM 872, has been considered to be useful in analgesia for both acute and chronic pain, there are no studies of its neurotoxicity and tolerance. We examined the spinal neurotoxicity and tolerance of YM 872 analgesia by repeated intrathecal administration in rats.Methods Male Sprague-Dawley rats with lumbar intrathecal catheters received YM 872 at 1µg·10µl^–1 (eight rats; YM group) or normal saline 10µl (eight rats; C group) intrathecally once a day for 30 days. We evaluated the analgesic effects every 3 days, by tail-flick test and behavioral side effects. On the 31st day, the lumbar spinal cord was removed from four randomly selected rats in each group for histological examination.Results The YM group showed significantly longer tail-flick latency when subjected to a high-intensity light beam than the C group at each measurement time point, although no significant changes in the latency according to the time course of the study were observed for the entire study period of 30 days in either group. No rats showed any side effects. Histologically, only slight lymphocytic cell infiltration and degeneration of myelinated fibers occurred, similarly in both groups. No changes were observed in the spinal cord in either group.Conclusion Administration of YM 872 (1µg) once a day for 30 days did not induce any tolerance and caused no histological changes in the spinal cord.     

Hospital Readmissions Following Abdominal Aortic Aneurysm Repair

In-hospital outcomes associated with abdominal aortic aneurysm (AAA) repair are well described. However, little is known about post-discharge readmission rates, lengths of stay, associated mortality, and costs. We examined 206 consecutive patients who underwent AAA repair at two American hospitals between 1998 and 2000. Index hospitalization and 6-month readmission data were extracted from a resource and cost accounting system used by both hospitals. Among the 206 patients, 183 survived until discharge (mortality rate 11.2%). Among the surviving patients, 38 (21.0%) were readmitted within 6 months. Half of the readmissions occurred within two weeks of discharge, with patients presenting with a diverse array of complications. Nonelective repair and diabetes mellitus were independent predictors of hospital readmission (OR=2.83, 95% CI=1.25-6.40, p=0.01; OR=6.60, 95% CI=1.02-42.4, p=0.047, respectively). For each readmission, the mean length of stay was 10.7±2.5 days and the mean cost was $13,397±3,381. The cumulative number of hospital days during the 6 months post-discharge was 17.7±3.5 days for each readmitted patient and the mean per-patient total cost was $23,262±5,478. The mortality rate among readmitted patients was 13.2%. Overall, readmissions following AAA repair accounted for a cost >50% over and above the cost of the readmitted patients index hospitalization. Hospital readmissions are common during the 6 months following AAA repair. Patients who are readmitted experience long lengths of stay and high mortality rates, and their care incurs high costs.Dr. Eisenberg is a Physician-Scientist of the Quebec Foundation for Health Research. Dr. Pilote is a Physician-Scientist of the Canadian Institutes for Health Research.     

Tracheal dilatation by halothane and enflurane in man

The effect of halothane and enflurane on tracheal tone were studied in 21 patients during the induction of anesthesia. Endotracheal tube cuff pressure was used to measure tracheal tone. Anesthesia, maintained by nitrous oxide 70% in oxygen, was supplimented with succinylcholine drip infusion to immobilize the patient. Ventilation was controlled by a Volume-preset ventilator. In the halothane group, the initial cuff pressure was 14.8 ± 1.3 (mean ± SE) cmH₂O but 10min after 0.15mg/kg of pancuronium injection, it increased to 21.7 ± 2.3cmH₂O (control). Ten min after inhalation of 0.75% of halothane, cuff pressure decreased to 14.7 ± 2.3cmH₂O (34 ± 11% decrease from the control value). In the enflurane group, the initial cuff pressure was 17.6 ± 1.8cmH₂O and it increased to 21.0 ± 1.7cmH₂O (control) 10min after pancuronium injection. Ten min after 1.7% of enflurane inhalation, cuff pressure decreased to 17.1 ± 2.3cmH₂O (23.9 ± 6% decrease from the control value). Halothane and enflurane produced similar tracheal dilatation in healthy individuals.(Yasuda I, Irimada M, Hirano T et al.: Tracheal dilatation by halothane and enflurane in man. J Anesth 2: 46–49, 1988)     

Safety of Contrast Venography prior to Caval Interruption in Patients with Renal Insufficiency

We undertook this study to determine whether the use of contrast venography would adversely affect renal function in patients with renal insufficiency requiring caval interruption. We conducted a retrospective review of all inferior vena cava (IVC) filters inserted at our institution over a 2-year period (January 2002 to January 2004). The indication for caval interruption, insertion technique, type of filter used, pre- and postintervention creatinine level, and the presence of diabetes and hypertension were analyzed. A total of 282 IVC filters were inserted, with 38 of them placed in patients with renal insufficiency as defined by a serum creatinine level of > 1.5 mg/dL. Contrast venography with 15 to 30 mL of iohexol (Omnipaque 300) was used in all cases, and no special measures other than proper hydration were used for renal protection. All filters were successfully deployed. The mean±SD preintervention creatinine level was 2.38±0.79 mg/dL. The mean±SD postintervention creatinine levels at 2 and 30 days were 2.26±0.45 mg/dL and 2.12±0.94 mg/dL, respectively. No patients required hemodialysis following caval interruption, and no adverse effect on renal function was noted. Contrast venography accurately delineates venous anatomy and facilitates proper caval filter placement with no apparent adverse effect on renal function. We believe contrast venography is safe even in the presence of renal insufficiency.     

Time-level relationship for nitric oxide and the protective effects of aminoguanidine in experimental spinal cord injury

Summary. Background. The secondary injury process following spinal cord trauma has been shown to involve different mechanisms such as excessive release of excitatory amino-acids, and induction of free radical induced lipid peroxidation. In this experimental study, the time-level relationship of the nitric oxide and the neuroprotective effects of aminoguanidine were investigated in a rat spinal cord trauma model.Methods. The experiments were performed on 63 Wistar albino rats divided into three groups; sham-operated control (Group 1), trauma created control (Group 2) and aminoguanidine group (Group 3). In groups 2 and 3, spinal cord trauma was produced at thoracic level by using weight the drop technique (at a severity of 50gr-cm). After the trauma, the rats in Group 3, received an intraperitoneal injection of 100mg/kg aminoquanidine twice a day for 3 days. The effects of the injury and the efficacy of aminoguanidine were determined based on biochemical parameters (lipid peroxidation and nitric oxide levels in tissue), and on light microscopy findings in cord tissue collected at different times post-injury. Biochemical parameters were performed one hour, three and five days after injury. Functional recovery was assessed at 3, and 5 days after cord trauma with the inclined-plane technique and Tarlovs motor grading scale.Findings. Although there was no statistically significant difference at the 1^st hour, the values of the tissue nitric oxide in trauma created controls were 42% higher on the 3^rd day and 40% higher on the 5^th day when compared with those in sham controls. The levels of the tissue lipid peroxidation in trauma created controls were 88% higher at the 1^st hour and 52.8% higher on the 5^th day when compared with shame controls, but there was no meaningful difference on the 3^rd day. In the trauma created control group, the mean motor function scores decreased to 1.16±0.40 and to 1±0 on the 3^rd and 5^th day, respectively. In this group the mean values of the inclined plane were 39.16±2.04 on the 3^rd day and 37.91±1.02 on the 5^th day. No statistically significant difference was observed in both tissue lipid peroxidation and nitric oxide levels for all time points between the aminoguanidine group and the sham-operated controls (p>0.01). The motor function scores were observed as 2.16±0.40 on the 3^rd day and as 3±0 on the 5^th day in aminoguanidine group. These values were significantly higher than the trauma created controls (p<0.01). Aminoguanidin treatment also improved the inclined plane performance of the rats; In this group, the mean values of the inclined plane scores were 44.58±2.92 and 52.91±1.88 on the 3^rd and 5^th days, respectively. These values were significantly higher than the trauma created controls (p<0.01).Interpretation. This study shows that the nitric oxide level does not increase in the spinal cord tissue during the first hour after the spinal cord trauma. It increases significantly in the spinal cord tissue not only three days but also five days following the trauma. Aminoguanidine treatment, which is started just after the trauma, can prevent both the nitric oxide production and lipid peroxidation in spinal cord tissue and it can improve the functional status of the animals. In this respect, aminoguanidine may have a potential role in the treatment of acute spinal cord injury.     

Changes of local brain tissue oxygen pressure after vasopressin during spontaneous circulation

Summary. Background. Brain tissue oxygen pressure (PbtO₂) correlates to cerebral blood flow (CBF) during spontaneous circulation, with one important regulator being nitric oxide (NO). Although it is established that arginine vasopressin (AVP) improves CBF and global cerebral oxygenation during cardiopulmonary resuscitation, it is unknown whether similar beneficial effects are present during spontaneous circulation. The purpose of this study was to investigate the effects of AVP with and without pre-treatment with the NO synthase inhibitor N-omega-nitro-L-arginine methyl ester (L-NAME) on local brain tissue oxygenation in a beating heart model.Methods. Following approval of the Animal Investigational Committee, nine healthy piglets underwent general anaesthesia, and were instrumented with a probe in the cerebral cortex to measure PbtO₂. Each animal was assigned to receive AVP (0.4U·kg^–1), and after a wash-out period, L-NAME (25mg·kg^–1 over 20min) followed by AVP (0.4U·kg^–1). After each AVP administration, nitroglycerine (25µg·kg^–1 over 1min) as a NO donor was infused to test the vascular reactivity independently from NOS inhibition.Findings. Three minutes after administration of AVP, PbtO₂ increased significantly (P<.05; mean±SEM, 31±11 versus 43±14mmHg, +39%), compared with baseline. After pre-treatment with L-NAME, the changes of PbtO₂ after AVP were not significant (32±11 versus 28±10, –13%) when compared with the baseline.Conclusion. In this beating heart porcine model, local brain tissue oxygenation was improved after AVP alone, but not after inhibition of NO synthesis with L-NAME.     

The neuromuscular effects of sevoflurane and isoflurane alone and in combination with vecuronium or atracurium in the rat

Sevoflurane was compared to isoflurane anesthesia alone and in combination with atracurium or vecuronium in 84 rats using the sciatic nerve—anterior tibialis muscle preparation. Both bolus injection and infusion rate techniques were used to evaluate these drug interactions. The ED₅₀ (dose which produced a 50% depression of twitch tension) of atracurium was 311 ± 31 and 360 ± 32µg·kg^–1 during 1.25MAC sevoflurane and isoflurane anesthesia respectively. The ED₅₀ of vecuronium was 190 ± 27 and 149 ± 14µg·kg^–1 during 1.25MAC sevoflurane and isoflurane anesthesia respectively. The mean infusion rates of atracurium and vecuronium required to maintain a 50% depression of twitch tension were 5.04 ± 0.7 and 2.02 ± 0.3mg·kg^–1·hr^–1. These infusion rates were 5.04 ± 0.7 and 2.02 ± 0.3mg·kg^–1·hr^–1 during 1.25MAC sevoflurane and 3.73 ± 0.3 and 1.81 ± 0.4mg·kg^–1·hr^–1 during 1.25MAC isoflurane anesthesia respectively. With both atracurium and vecuronium, the infusion rate required to maintain a 50% depression twitch of tension was inversely related to the concentrations of isoflurane and sevoflurane. The authors conclude that sevoflurane is similar in potency to that of isoflurane in augmenting a vecuronium or atracurium induced neuromuscular blockade in a dose-dependent manner.(Shin YS, Miller RD, Caldwell JE, et al.: The neuromuscular effects of sevoflurane and isoflurane alone and in combination with vecuronium or atracurium in the rat. J Anesth 6: 1–8, 1992)     

Effects of Cilostazol on Human Venous Smooth Muscle

In this study, we evaluated the effect of therapeutic doses of cilostazol on human venous smooth muscle. Saphenous vein rings (two to four per patient sample) were suspended in tissue baths for isometric tension recordings. At the beginning of the experiment, optimal tension for isometric contraction was achieved for each ring in a stepwise fashion in the presence of norepinephrine (10^–2 M). Norepinepherine was then added cumulatively in half-molar increments and isometric tension developed by the rings was measured, thereby obtaining a dose-response curve. Following washout and reequilibration, the rings were precontracted with a 30-50% submaximal dose of norepinepherine determined from the dose-response curve and allowed to contract until a stable plateau was reached. Cilostazol was then added in a cumulative manner (680-2,720 g/L), and the tension generated was recorded. A total of 76 venous rings were tested, and all relaxed in the presence of cilostazol. The amount of relaxation increased as the concentration of cilostazol increased. Relaxation of 15±1.9% (mean±SEM) at low cilostazol doses (680 g/L) to 37±3% at high cilostazol doses (2,720 g/L) was demonstrated. A second finding of this study was demonstrated when the patient samples were divided according to the presence or absence of risk factors for arteriosclerosis. The specific risk factors examined included diabetes mellitus, smoking, hypercholesterolemia, and hypertension. The presence or absence of hypertension (n=52) or hypercholesterolemia (n=18) did not affect the amount of relaxation of the venous rings. Smokers (n=46) had less relaxation 16±2.4% (680 g/L) to 41±3.6% (2,720 g/L) compared to nonsmokers (n=53) who relaxed 22±3.5% (680 g/L) to 48±5.7% (2720 g/L). This did not reach statistical significance at any concentration cilostazol (p=0.11-0.18). Diabetics (n=53) did have statistically significantly less relaxation at every concentration of cilostazol compared to nondiabetics (n=11, p < 0.05). All venous rings relaxed in the presence of cilostazol. Veins of nondiabetics relaxed statistically significantly more than those of diabetics. Smokers had less relaxation than non-smokers, but this was not statistically significant. We are the first to demonstrate that human venous smooth muscle cells undergo relaxation when exposed to therapeutic concentrations of cilostazol.     

Comparison of anesthetic effects of epidural and intravenous administration of buprenorphine during operation

Thirty six patients were received epidural anesthesia with or without buprenorphine (BPN) during upper abdominal surgery. They were divided into three groups of 12 patients as follows; G-I received 20ml of 1% lidocaine epidurally, G-II received 20ml of 1% lidocaine epidurally and 0.6mg BPN intravenously, G-III received 20ml of 1% lidocaine with 0.6mg BPN epidurally. Additional 5ml of 1% lidocaine was given to any patient if systolic blood pressure or heart rate increased 10% compared to control value. Trachea was intubated following anesthetic induction with thiopental. The lungs were ventilated with a mixture of N₂O/O₂ (33%) and pancuronium was used for muscle relaxation. The total required doses of lidocaine in G-II and G-III were decreased 60% compared to control group (G-I) (P 0.05). The mean period of time until the first administration of pentazocine for postoperative pain was 13 ± 10hr (mean ± SD) in G-II and 19 ± 24hr in G-III compared to 5 ± 4hr in G-I (P 0.001). The dose of the administration of pentazocine that was required for pain relief during the first 48 postoperative hr in G-III was 54 ± 10mg (mean ± SD) compared to 150 ± 21mg in G-I (P 0.02) and 106 ± 28mg in G-II (P 0.05). Recovery from anesthesia in G-III was more rapid than that in G-I (P 0.05). The Pa_{CO 2} values in G-II and G-III increased 15% compared to control group at about 4hr and 8hr after administration of BPN, but any clinical treatment was not needed for them. Nonrespiratory side effects, e.g., nausea, vomiting, fatigue and headache, were comparably common in all groups. Mild hematuria associated with acute hypotension occurred in two patients in G-II (17%) immediately after the intravenous injection of 0.6mg of BPN. The results showed that 0.6mg of BPN given epidurally demonstrated better anesthetic and more potent postoperative analgesic effects and lesser side effects than 0.6mg of BPN given intravenously in patients undergoing upper abdominal surgery.(Yonemura E, Fukushima K.: Comparison of anesthetic effects of epidural and intravenous administration of buprenorphine during operation. J Anesth 4: 242–248, 1990)     

Effects of calcium and temperature on tension in isolated canine coronary artery

The effects of calcium and temperature on the tension of isolated canine coronary arterial strips were studied.In 20mEq·l ^–1 K solution, the tension was significantly increased from 0mg with 0mEq·l ^–1 Ca to 33 ± 18mg with 0.2mEq·l ^–1 Ca at 37°C, from –40 ± 18mg with 0mEq·l ^–1 Ca to –17 ± 11mg with 0.2mEq·l ^–1 Ca at 30°C, from –77 ± 19mg with 0mEq·l ^–1 Ca to –52 ± 17mEq·l ^–1 with 1mEq·l ^–1 Ca at 25°C, from –88 ± 13mg with 0mEq·l ^–1 Ca to –41 ± 18mg with 2mEq·l ^–1 Ca at 20°C, from –125 ± 16mg with 0mEq·l ^–1 Ca to –116 ± 13mg with 2mEq·l ^–1 Ca at 15°C. Ca higher than 0.2mEq·l ^–1 produced a dose-dependent increase in tension between 37°C and 15°C. In spite of the presence of 4mEq·l ^–1 Ca, the development of tension was strongly supressed by lowering the temperature below 20°C, and completely inhibited at 10°C. The rate of a decrease in tension caused by cooling was about 5.5mg·°C^–1.This study demonstrated that Ca²⁺ produced a dose-dependent increase in tension in high-K solution, which was suppressed as the temperature was lowered.(Yoshida K, Fujii Y, Ina H, et al.: Effects of calcium and temperature on tension in isolated canine coronary artery. J Anesth 5: 172–176, 1991)     

Inhaled Nitric Oxide Therapy After Fontan-Type Operations

Purpose Inhaled nitric oxide (NO) therapy is a newly developed strategy designed to reduce pulmonary vascular resistance after the Fontan-type operation. We reviewed our experience to evaluate its efficacy and true indications.Methods We retrospectively examined 47 children who received inhaled NO therapy after the Fontan-type operation between August 1996 and December 2002. The maximal dose of NO ranged from 5 to 30ppm (median 10ppm), and the duration of inhaled NO therapy ranged from 5h to 52 days (median 2 days).Results Inhaled NO significantly decreased the central venous pressure (CVP), from 16.2 ± 2.2 to 14.6 ± 2.2mmHg (P < 0.0001), and the transpulmonary pressure gradient between the CVP and left atrial pressure, from 9.9 ± 2.9 to 8.4 ± 2.7mmHg (P < 0.0001). It also increased the systolic systemic arterial pressure from 71.9 ± 15.2 to 76.8 ± 14.5mmHg (P < 0.05). In 26 patients with additional fenestration, inhaled NO led to a significant improvement in SaO₂ from 90.1% ± 9.6% to 93.3% ± 7.9% (P < 0.01). However, patients with a CVP <15mmHg or a transpulmonary pressure gradient <8mmHg, or both, after the Fontan-type operation, showed no significant changes in hemodynamics during inhaled NO therapy.Conclusions We propose that a CVP 15mmHg or a transpulmonary pressure gradient 8mmHg, or both, after Fontan-type operations are appropriate indications for inhaled NO therapy.     

Plasma concentration for optimal sedation and total body clearance of propofol in patients after esophagectomy

The present study investigated plasma propofol concentration for optimal sedation and total body clearance in patients who required sedation for mechanical ventilation after esophagectomy. Seven patients after esophagectomy were enrolled in this study. Plasma propofol concentrations were measured with high performance liquid chromatography. Total body clearance was calculated from the steady-state concentration. The infusion rate of propofol for achieving the sedation score of level 3 (drowsy, responds to verbal stimulation) was 1.74 ± 0.82mgkg^–1h^–1 (mean ± SD, n = 7) when the plasma propofol concentration and the total body clearance were 0.85 ± 0.24µgml^–1 and 1.83 ± 0.54lmin^–1 (mean ± SD, n =7), respectively.     

A Prostacyclin Analogue,OP-41483α-CD,Restores the Ability of a β<Subscript>2</Subscript>-Adrenergic Agonist to Stimulate Alveolar Fluid Clearance in Rats

Purpose. It is not yet known whether a prostacyclin analogue can affect alveolar fluid clearance. According to recent studies, high-dose (10^–3M) terbutaline, a ₂-adrenergic agonist, failed to increase alveolar fluid clearance. Therefore, we examined the effects of OP-41483-CD, a prostacyclin analogue, on alveolar fluid clearance in the presence of high-dose terbutaline in rats.Methods. Albumin solution containing Evans blue dye and various drugs was instilled into the alveolar airspaces of isolated rat lungs, which were then inflated with 100% oxygen at an airway pressure of 8cmH₂O. Alveolar fluid clearance was measured by the progressive increase in dye concentrations over 1h.Results. Although 10^–5 and 10^–4M terbutaline increased alveolar fluid clearance, 10^–3M terbutaline did not. OP-41483-CD restored the ability of 10^–3M terbutaline to stimulate alveolar fluid clearance. The effect of OP-41483-CD was consistent with the effect of atenolol, a ₁-adrenergic antagonist. The effect of OP-41483-CD on alveolar fluid clearance was unchanged in lungs inflated with nitrogen. Prostaglandin E (PGE)₁ and PGE₂ analogues had similar effects to OP-41483-CD on alveolar fluid clearance.Conclusion. These results indicate that a prostacyclin analogue restores the ability of high-dose terbutaline to stimulate alveolar fluid clearance.     

Comparative study of intravenous administration of Ringer’s lactate,Ringer’s acetate and 5% glucose containing these Ringer’s solutions in human being

The effects of the administration of Ringers lactate (L) and Ringers acetate (A) solution on blood biochemistry in human subjects operated for tympanoplasty under general anesthesia were investigated. And the feasibilities of the clinical use of Ringers lactate (LD) and Ringers acetate (AD) solution containing 5% glucose were also assessed. In all cases the rate of infusion was 500ml for initial 20min, and then 5ml·hr^–1·kg^–1 B.W. for 3hr and 10min.There were significant increases in blood L- and D-lactate, pyruvate, and L-lactate/pyruvate ratio in L group. A significant increase in blood acetate but not lactate was found in A group. These metabolic changes were minimal and considered as clinically not significant. The urinary excretion of lactate, pyruvate, acetate and glucose were also negligible. In both LD and AD group, the higher blood concentrations of lactate, pyruvate, acetate and glucose were found than in L and A group. Urinary excretions of these metabolites were much higher in LD and AD group than in L and A group. So glucose containing Ringers lactate or acetate solutions should be administered in appropriate amounts and rate not to induce clinically significant metabolic alterations.(Kuze S, Naruse T, Ito Y et al.: Comparative study of intravenous administration of Ringers lactate, Ringers acetate and 5% glucose containing these Ringers solutions in human being. J Anesth 4: 155–161, 1990)     

Percutaneous and Open Renal Revascularizations Have Equivalent Long-Term Functional Outcomes

Atherosclerotic renal artery stenosis is a significant cause of poorly controlled hypertension and progressive renal dysfunction leading to ischemic nephropathy and other end-organ damage. The optimal treatment of renovascular disease contributing to hypertension and renal dysfunction is not known. This study compares the anatomic and functional outcomes of both open and endovascular therapy for chronic, symptomatic atherosclerotic renal artery disease. We performed a retrospective analysis of records from patients who underwent renal arterial interventions, endovascular or open bypass, between January 1984 and January 2004. Principal indications for intervention were hypertension (51%), chronic renal insufficiency (13%), and hypertension and elevated creatinine (36%). A total of 247 patients (109 males; mean age 69±10, range 44–89 years) underwent 314 interventions (109 open procedures; 205 angioplasties, 71% with stent placement). There was a significant difference in 30-day mortality (4% vs. <1%; p < 0.005) between the open and endoluminal groups, but not at 1, 3, or 5 years. Patients in the open group had a higher primary patency rate at 5 years (83±5% vs. 76±6%; p=0.03), but patients in the endoluminal group had a higher assisted primary patency rate at 5 years (92±5% vs. 84±5; p=0.03). There was no significant difference between both treatment groups in cumulative freedom from presenting symptom or in freedom from dialysis and renal-related death. Patients who presented with hypertension were more likely to have shown improvement in their blood pressure with endoluminal intervention at 1, 3, and 5 (59±6% endoluminal vs. 83±5% open; p=0.01) years. From these results we conclude that open repair and endoluminal repair of atherosclerotic renal artery stenosis have similar immediate and long-term functional and anatomic outcomes. Patients who present with hypertension may have greater benefit with an endoluminal repair.Presented at the Twenty-ninth Annual Meeting of the Peripheral Vascular Surgery Society, Anaheim, CA, June 4-5, 2004.     

The effects of calcium antagonists on EEG,evoked potentials and neurologic recovery after complete global brain ischemia for 15 minutes in dogs

The effects of three calcium antagonists on the recovery from neurologic damages after complete global brain ischemia were examined by evaluating the change of a electroencephalogram (EEG), evoked potentials (EP) and a neurologic recovery score (NRS) in dogs. Fifteen minutes global brain ischemia was achieved by occluding the ascending aorta and the caval veins. Nicardipine (NC), flunarizine (FL) and diltiazem (DL) were administered with continuous infusions for three days after the ischemia. The EEG-EP scores (0:no response – 6:normal) 3hr after the ischemia were 1.4 ± 0.4 (mean ± SE) in the control, 2.2 ± 0.3 in the NC, 2.2 ± 0.4 in the FL and 2.1 ± 0.2 in the DL. There were no significant differences between the 4 groups. The survival rates on the 7th day after the ischemia were 67% (6/9) in the control, 78% (7/9) in the NC, 56% (5/9) in the FL and 89% (8/9) in the DL. No significant differences were presented between the 4 groups. The NRSs (0:death – 100:normal) on the 7th day were 40.3 ± 7.3 in the control, 59.0 ± 8.5 in the NC, 63.2 ± 9.7 in the FL and 55.7 ± 3.3 in the DL. Each treated group showed a tendency to have a higher NRS than that in the untreated control group. The NRS in all dogs treated by the Ca⁺⁺ antagonists on the 7th day was 58.7 ± 4.1, which was significantly higher than that in the control group (P < 0.05). We conclude that the continuous administration of calcium antagonists for three days after the global brain ischemia would be beneficial for the neurologic recovery.(Ono K, Iwatsuki N, Takahashi M, et al.: The effect of calcium antagonists on EEG, evoked potentials and neurologic recovery after complete global brain ischemia for 15 minutes in dogs. J Anesth 5: 114–122, 1991)