Hemodynamic and catecholamine responses during tracheal intubation using a lightwand device (Trachlight) in elderly patients with hypertension

Purpose.Tracheal intubation using a lightwand device (Trachlight) should minimize hemodynamic change by avoiding direct-vision laryngoscopy. We evaluated hemodynamic and catecholamine responses during tracheal intubation using a Trachlight in elderly patients with hypertension.Methods.Twenty-six hypertensive patients aged over 65 years undergoing orthopedic surgery were randomly divided into two groups, group L (n = 13) and group T (n = 13). Anesthesia was induced with fentanyl (2g·kg^–1) and propofol (1.5mg·kg^–1), and then muscle relaxation was obtained with vecuronium (0.15mg·kg^–1). The trachea was intubated with either a Macintosh laryngoscope (group L) or a Trachlight (group T). Hemodynamics, plasma catecholamine concentrations, and arterial blood gases were measured before the induction of anesthesia (T0), before tracheal intubation (T1), immediately after tracheal intubation (T2), and 3min after tracheal intubation (T3).Results.The intubation time was shorter in group T than in group L (12.6 ± 1.7 vs 23.5 ± 2.9s, mean ± SE; P 0.01). Compared with the preinduction (T0) value, systolic blood pressure (SBP) showed a significant decrease at T1 and T3 in group L and at T1, T2, and T3 in group T. The heart rate (HR) and plasma norepinephrine (NE) concentration showed no change in either group throughout the time course, whereas the plasma epinephrine (E) concentration showed a significant decrease at T2 and T3 in both groups. The mean values of the rate-pressure product (RPP: HR × SBP) were less than 15 000 after tracheal intubation in both groups. There was no significant difference in hemodynamic or catecholamine responses between groups at any point. No patient had ischemic ST-T changes in either group.Conclusion.A lightwand has no advantage over a laryngoscope in terms of hemodynamic and plasma catecholamine responses to tracheal intubation in elderly patients with hypertension, despite a shorter intubation time.     

Enhancement of lidocaine-induced epidural anesthesia by deoxyaconitine in the rabbit

Purpose.Aconiti tuber has been used in traditional Oriental medicine to alleviate pain. The antinociceptive property of aconiti tuber is due to the action of its extracted alkaloids such as deoxyaconitine. The purpose of this study was to investigate the effect of epidural deoxyaconitine on epidural lidocaine anesthesia. Methods.Five adult rabbits were used. Three different combinations of drugs were injected into the epidural space, in the following order: first (combination A), 1.5ml of 2% lidocaine; second (combination B), 1.5ml of 2% lidocaine and 150µg deoxyaconitine; and third (combination C), 3mg nor-binaltorphimine followed by 1.5ml of 2% lidocaine and 150µg deoxyaconitine 30min later. The latency of onset and the duration of three end-points (sensory loss in the tail, loss of weight-bearing ability, and flaccid paresis of hind limb) were measured. Results.Onset times for the three end-points were not changed by deoxyaconitine or by nor-binaltorphimine. The duration of sensory loss was 27.0 ± 2.7min, the duration of loss of weight-bearing ability was 33.0 ± 2.7min, and the duration of flaccid paresis was 21.0 ± 4.2min in the combination A group. In the combination B group, deoxyaconitine extended the time of sensory loss by 80%, the time of loss of weight-bearing by 50%, and that of flaccid paresis by 60% compared with the combination A group. In the combination C group, this phenomenon was partially antagonized by pretreatment with nor-binaltorphimine, a -opioid antagonist. Conclusions.Based on our observations, deoxyaconitine enhanced epidural lidocaine anesthesia in the rabbit, and this effect seemed to be partly mediated by -opioid receptors.     

Hemodynamic and bispectral index responses to tracheal intubation during isoflurane or sevoflurane anesthesia

Purpose.The effects of volatile anesthetics on change in the bispectral index (BIS) due to tracheal intubation are unclear. We investigated hemodynamic and BIS responses to intubation during isoflurane or sevoflurane anesthesia. Methods.After obtaining Institutional Review Board approval and informed consent, we randomly allocated 40 patients of American Society of Anesthesiologists (ASA) physical status I to receive either isoflurane (ISO group; n = 20) or sevoflurane (SEV group; n = 20). The patients were anesthetized with thiamylal and were ventilated with 100% oxygen, using a mask. The inspired concentrations of isoflurane and sevoflurane were gradually increased and maintained at end-tidal anesthetic concentrations of 2 minimum alveolar concentration (MAC) during the study period. Tracheal intubation was performed 15min after the end-tidal anesthetic concentrations had reached 2 MAC. Mean arterial pressure (MAP), heart rate (HR), and BIS were recorded before induction, at the loss of consciousness, before laryngoscopy, and at 1, 3, and 5min after intubation. Results.Anesthesia with 2 MAC volatile anesthetics increased HR in the ISO group, and decreased MAP in the SEV group. The BIS value decreased from 95 ± 3 and 96 ± 2 before thiamylal to 39 ± 9 and 38 ± 10 before intubation in the ISO and SEV groups, respectively. MAP and HR were significantly increased in both groups 1 and 3min after intubation, but BIS remained unchanged. Conclusion.Anesthesia with 2 MAC of isoflurane and sevoflurane was effective to suppress the change in BIS due to intubation but was not sufficient to prevent changes in hemodynamic responses.     

Comparison of hemodynamic and anesthetic effects of hyperbaric bupivacaine and tetracaine in spinal anesthesia

Purpose.To compare the anesthetic and hemodynamic effects and the predictive factor of anesthesia level of commonly used preparations of hyperbaric bupivacaine and tetracaine in spinal anesthesia. Methods.Two hundred patients aged 40 to 75 years with ASA physical status I or II were anesthetized spinally via the L4–5 interspace using 0.5% hyperbaric bupivacaine in 7.27% glucose (Bupivacaine group, n = 100) or 0.5% hyperbaric tetracaine dissolved in a 10% glucose solution (Tetracaine group, n = 100) in a lateral position. The volume of anesthetic used was decided by the resident according to the surgical procedure. Patients were returned to the supine position immediately after drug injection. Blood pressure, heart rate, and anesthesia level tested by cold sensation were measured for 30min. Results.Blood pressure and heart rate decreased significantly but without any differences between the groups. The volume of drug used was significantly larger in the Bupivacaine group (2.6 ± 0.5ml) than in the Tetracaine group (2.1 ± 0.4ml) to obtain the same maximum anesthesia level. The time to reach the maximum anesthesia level was significantly longer in the Bupivacaine group (18 ± 7min) than in the Tetracaine group (15 ± 6min). The volume of the drug was the only predictive factor of the maximum anesthesia level in both groups: Level (as expressed by the number of anesthetized segments from S5 to cephalad) = 1.55 × (volume in ml) + 13.06 in the Bupivacaine group, and 2.59 × (volume) + 11.46 in the Tetracaine group. Conclusion.In spinal anesthesia, hyperbaric tetracaine in 10% glucose induced a faster and higher spread of anesthesia than hyperbaric bupivacaine in 7.27% glucose without any differences in hemodynamics.     

The effect of craniotomy location on postoperative pain and nausea

Purpose.At least one retrospective study has suggested that the need for postoperative control of pain and nausea depends on the location of the cranial surgery. This prospective study was performed to examine the hypothesis that patients who have had infratentorial craniotomy experience more severe pain and more frequent nausea than those with supratentorial procedures. Methods.We compared postoperative outcomes in 28 patients with infratentorial craniotomy, 53 with supratentorial craniotomy, and 47 with complex spinal cord surgery (the control group). Anesthesia was standardized for all three groups and the concentration of isoflurane was titrated to keep mean arterial pressure within 30% of preoperative values. Severity of pain and frequency of nausea and vomiting were recorded for 24h after surgery. Pain was assessed with a verbal pain score scale of 0–10, with 10 being the worst pain imaginable. Data were collected for 24h postoperatively. Results.Because nausea and pain diminish drastically 2h after surgery, pairwise differences were assessed at each point within the first 2h. Within 30min of extubation, median pain scores in the supratentorial and spine groups rose to 2 and in the infratentorial group to 5. The statistical differences between groups were not significant (P > 0.06) by logistic regression. Also, the incidence of nausea was not significantly different (57% supratentorial, 57% spine, 67% infratentorial; P = 0.62) by Dunns procedure. Conclusion.There were no significant differences in the severity of pain or the frequency of nausea based on the craniotomy site.     

Propofol inhibits lidocaine metabolism in human and rat liver microsomes

Purpose.When two drugs are metabolized by similar P450 isoforms, one drug inhibits the metabolism of the other when both the present. The metabolism of lidocaine and propofol can be mediated by similar P450 isoforms. Therefore, we investigated the relationship in the metabolism between lidocaine and propofol in both rat and human liver microsomal P450 (CYP) systems in vitro. Methods.(1) Propofol, 4µg·ml^–1, as the substrate and lidocaine (between 0.5 and 8µg·ml^–1) and (2) lidocaine, 4.7µg·ml^–1, as the substrate and propofol (between 0.5 and 40µg·ml^–1) were reacted separately with human and rat microsomes. The concentrations of lidocaine, its major metabolite (monoethylglycinexylidide, MEGX) and propofol were measured using high-pressure liquid chromatography. The metabolism of lidocaine was presented as a reaction activity (MEGX/lidocaine). Results.The dose-dependent inhibitory effects of propofol on lidocaine metabolism were observed in both the human and rat groups. The IC50 (the concentration producing 50% maximal inhibition) of propofol was 5.0µg·ml^–1 and 0.70µg·ml^–1 in the human and the rat groups, respectively. The propofol concentration of 5.0µg·ml^–1 is within the range of clinical doses for humans. On the other hand, lidocaine did not change propofol metabolism. Conclusion.Propofol possesses a dose-dependent inhibitory effect on the metabolism of lidocaine in both human and rat CYP systems in vitro.     

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)     

Temperature and humidity of the DrÄger Cato anesthetic machine circuit

Purpose.The DrÄger Cato anesthetic machine (DrÄger, LÜbeck, Germany) effectively humidifies and warms anesthetic gases, because it has a built-in hotplate to heat the breathing system, and expired gas passes through the CO₂ absorbent three times during one breath. In the present study, we measured the temperature and absolute humidity (AH) of the anesthetic circuit in the DrÄger Cato machine with and without heat moisture exchangers (HME), and compared them with those in another anesthetic machine, the Aestiva/5 (Datex-Ohmeda, Helsinki, Finland).Methods.Forty-eight adult patients were randomly assigned to one of eight groups according to the anesthetic machine, fresh gas flow (FGF), and the use of HME (n = 6 each): Cato 0.5l·min^–1 without HME (group 1), Cato 1.0l·min^–1 without HME (group 2), Cato 0.5l·min^–1 with HME (group 3), Cato 1.0l·min^–1 with HME (group 4), Aestiva 0.5l·min^–1 without HME (group 5), Aestiva 1.0l·min^–1 without HME (group 6), Aestiva 0.5l·min^–1 with HME (group 7), and Aestiva 1.0l·min^–1 with HME (group 8). The temperature and AH of the anesthetic gases were measured with a Moiscope (S.K.I. Net, Tokyo, Japan), which was placed between the endotracheal tube and the Y-piece of the anesthetic circuit. The HME was placed between the Moiscope and the Y-piece of the anesthetic circuit. The temperature and AH of the anesthetic gases were measured at 5, 10, and 15min and then every 15min up to 150min after tracheal intubation.Results.Among the groups without HME (groups 1, 2, 5, and 6), the inspired temperatures and AH in groups 1 and 2 were significantly higher than those in groups 5 and 6 at all times during the study period (P 0.01–0.001). The inspired temperatures and AH of the groups with HME (groups 3, 4, 7, and 8), were significantly higher than those in groups 2, 5, and 6 (P 0.01–0.001). Among the groups with HME, the AH in group 3 was significantly higher than that in group 8 until the final study period.Conclusion.The present study indicates that the DrÄger Cato machine was more effective in warming and humidifying respiratory gas than the Aestiva/5, and that Aestiva/5 without HME does not reach the optimal temperature and humidity ranges, even if minimal flow anesthesia (0.5l·min^–1) is performed.     

Survey of patients whose lungs could not be ventilated and whose trachea could not be intubated in university hospitals in Japan

Purpose.We conducted a survey to clarify the actual circumstances in which the lungs could not be ventilated and the trachea could not be intubated (CVCI). Methods.A questionnaire was mailed to all the university hospitals in Japan, asking about CVCI they had experienced during induction of anesthesia in 1998, and before 1997. Results.Answers were obtained from 60 of 83 institutes. CVCI occurred in 26 of 151900 cases of general anesthesia (0.017%) in 1998. Eighteen cases occurred after induction of anesthesia by several induction methods. Five cases occurred after repeated attempts at tracheal intubation by laryngoscopy and fiberscopy in patients under awake or anesthetized conditions. In the remaining 3 cases, the situation of occurrence was not documented. Patients with CVCI had anatomical abnormalities around the upper airways, mostly from acquired diseases. CVCIs after induction of anesthesia were successfully treated by restoration of spontaneous respiration, blind intubation, laryngeal mask airway, and transtracheal approaches, and CVCIs after repeated attempts at intubation were treated mostly by transtracheal approaches. No serious consequences occurred in any patients in 1998. Twenty cases were reported before 1997, and 2 were specific, in which CVCI followed malplacement of a tracheal tube, and serious consequences, death and brain damage, respectively, followed. In other patients, no serious consequences occurred, although cardiac arrest occurred in 1 patient. Conclusion.This survey demonstrates that CVCI can occur in any situation in which the airway is not established. Furthermore, effective treatments may be different depending on the situation, and delayed recognition of tracheal tube misplacement may lead to a serious outcome.     

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.     

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)     

Comparison of adjuvant anesthetics for propofol induction

Purpose.Fentanyl was compared with nitrous oxide/sevoflurane as an adjuvant anesthesia to propofol during induction.Methods.Two-hundred sixty-three patients of American Society of Anesthesiologists physical status 1 or 2 undergoing minor surgery were randomly divided into two groups. Group F patients (n = 125) received 2g·kg^–1 fentanyl and 1.8mg·kg^–1 propofol, and were ventilated by mask with oxygen. Group S patients (n = 138) received 1.8mg·kg^–1 propofol, followed by inhalation of 4% sevoflurane in N₂O (4l·min^–1) and oxygen (2l·min^–1) by mask. The trachea was intubated exactly 2, 3, 4, or 5min after injection of 0.1mg·kg^–1 vecuronium, and the conditions of endotracheal intubation were scored according to the patients' responses to laryngoscopy and endotracheal intubation. Systolic blood pressure (SBP) and heart rate (HR) were measured before and after endotracheal intubation. The cost of anesthetics was also calculated.Results.No significant differences in SBP were observed between the groups throughout the induction period. HR did not change from preanesthetic values in group F. In contrast, HR in group S patients increased by 9–18 beats·min^–1 (bpm) after inhalation of N₂O/sevoflurane and further increased by 17–21bpm following endotracheal intubation. Significant differences in HR were noticed between the groups (P 0.001). The conditions of endotracheal intubation were similar in the two groups and were satisfactory when mask ventilation exceeded 3min. Fentanyl was less expensive than sevoflurane/N₂O anesthesia when mask ventilation exceeded 3min.Conclusion.From the standpoints of hemodynamics and drug cost, fentanyl is preferable to N₂O/sevoflurane inhalation as an adjuvant to propofol during induction, because mask ventilation for more than 3min was required for satisfactory endotracheal intubation.     

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.     

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.     

Analgesic dose-response relation in cervical epidural block

The relationship between the age and the spread of analgesia from different epidural anesthetic doses was examined by studying analgesic dose responses in cervical epidural analgesia. Two different anesthetic doses (5ml or 10ml) of 2% mepivacaine were injected into the cervical epidural space at a constant pressure (80mmHg) using an intravenous apparatus, and the spread of analgesia to pinprick was assessed. The significant correlation was found between the patients age and the number of spinal segments blocked (5ml:r = 0.8498, P < 0.01, 10ml:r = 0.5988, P < 0.01). The inverse linear relationship was found between the patients age and the segmental dose requirement (5ml:r = –0.6754, P < 0.01, 10ml:r = –0.5784, P < 0.01). Patients under 39 years of age showed a direct relationship between the dose injected and the number of spinal segments blocked, enabling prediction of the number of segments blocked with a given dose of local anesthetic. Doubling the epidural dose approximately doubled the number of spinal segments blocked. The analgesic dose-response relation in patients over 60 years of age differed from that in patients under 39 years of age and doubling the epidural dose did not double the number of spinal segments blocked. Progressively more extensive analgesia was obtained from a given dose of local anesthetic with advancing age. It was difficult to limit the extent of analgesia by injecting a smaller dose of local anaesthetic in the elderly.(Hirabayashi Y, Matsuda I, Inoue S et al.: Analgesic dose-response relation in cervical epidural block. J Anesth 2: 22–27, 1988)     

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.     

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.     

Temporal Lift by Galeapexy: A Review of 270 Cases

The purpose of this technique is to correct the ptotic tail of the brow and crows feet as well as to redrape the premalar skin to allow us to make a greater skin resection in the lower lid. The purpose of this presentation is to expose the advantages, the inconveniences, and the complications of this technique. We reviewed the charts of 270 patients who were operated on between June 1996 and January 2002. The average age of the patients was 45 years old. Temporal lifts were performed during a frontotemporal lift in 92 cases, and during a three-stage lift (frontal, facial, and cervical) in 170 cases. In eight cases, an isolated temporal lift was performed. An upper blepharoplasty was performed in 252 cases and transconjunctival fat pad excision was performed in 188 cases. Finally, a lower lid skin resection was done following a galeapexy in 241 cases. The surgical approach consists of a temporal incision, followed by a subgaleal dissection, and then a subcutaneous dissection that allows the cephalic galea, previously incised, to be anchored to the temporal aponeurosis. This allows good cutaneous redraping that raises the brow tail and a detachment of the orbicularis fibers. The suturing of the scalp is done without tension and without eliminating hair. The results of the technique with a follow-up period of more than five years for the earlier cases and six months for the last cases, were evaluated with three criteria: (1) the distance between the brow and the eyelashes, (2) the reduction of crows feet, (3) the reduction of wrinkles at the level of the lower lid and the malar region. Overall satisfaction was also rated. Of 270 patients, 225 had ratings of very good to good, 13 had average results, and 13 had unsatisfactory results. As far as complications, five had unilateral hematoma requiring an evacuation, four patients had temporary alopecia, and eight patients had temporary frontal muscle weakness that resolved within one to three months. This technique, performed under local anesthesia, is very efficient, reproducible, and simple. The incidence of complications can be reduced when one is meticulous during dissection. Presented at the Congress of the European Association of Plastic Surgeons in Madrid, Spain, in May of 1999 and at the ISAPS Postgraduate Course in Beirut, Lebanon, May 2001.     

Tetracycline double-labeling of iliac trabecular bone in 41 normal adults

Summary A histomorphometric evaluation of the iliac crest trabecular bone remodeling was performed after tetracycline double-labeling in 41 normal Danes (12 males and 29 females) aged 19 to 56 years. The fraction of formative (osteoid covered) and resorptive surfaces was unrelated to age but higher in males than in females (P<0.02 andP<0.05, respectively). The appositional rate (0.65±0.12 m/day) was unrelated to age and sex, whereas the fractional labeled surfaces were higher (P<0.01) in the males (0.18±0.08 m²/m²) than in the females (0.12±0.05 m²/m²), and among the females inversely related to age (R=–0.38,P<0.05). The bone formation rate at BMU level (0.50±0.20 m³/m²/day) was unrelated to sex, but among the females inversely related to age R=–0.49,P<0.01). The bone formation rate at tissue level was higher (P<0.02) in the males (0.13±0.07 m³/m²/day) than in the females (0.07±0.03 m³/m²/day) and among the females inversely correlated to age (R=–0.43,P<0.05). The age- and sex-dependent variations in the dynamic parameters underline the importance of a more elaborated normal material.     

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)