Dental practices continue to enlarge: even in the state of Illinois

OBJECTIVES: To determine the effect of propofol on pulmonary short circuit or shunt (Qs/Qt). PATIENTS AND METHODS: Nine patients undergoing scheduled thoracic surgery with single lung ventilation were studied. All patients were anesthesized with 2 mg/kg propofol followed by a continuous infusion of 4-6 mg/kg/h; fentanyl 0.3 mg followed by bolus as needed; and relaxed with atracurium 0.5 mg/kg followed by bolus of 0.1-0.2 mg/kg as needed. The ratio Qs/Qt was calculated with an FiO2 of 1 and patients in lateral decubitus. RESULTS: During double-lung ventilation Qs/Qt was 17.4 +/- 5.4% and PO2 was 430 +/- 16 mmHg, while shunt increased to 27.8 +/- 8.4% and PO2 decreased to 258 +/- 127 mmHg during single-lung ventilation. Change was significant in both cases. CONCLUSIONS: Continuous infusion of propofol produces a significant increase of Qs/Qt and a significant decrease of PaO2 during single-lung ventilation for thoracic surgery.     

Hepatocyte nuclear factor-4 alpha gene mutations in Japanese non-insulin dependent diabetes mellitus (NIDDM) patients

OBJECTIVE: To assess the effect of pregnancy, maternal position, and cardiac output on intrapulmonary shunting (Qs/Qt) in normotensive nulliparous women near term. METHODS: Ten normotensive nulliparas between 36 and 38 weeks' gestation underwent pulmonary artery catheterization (via the subclavian route) and radial artery canalization. Baseline assessments were made with subjects in the left lateral recumbent position after a 30-minute stabilization period. Measurements were obtained sequentially in the left lateral, right lateral, supine, knee-chest, sitting, and standing positions. Each position change was followed by a 10-minute pre-measurement stabilization period. Cardiac output was measured via the thermodilution technique. Blood samples were obtained simultaneously from the pulmonary and radial arteries and analyzed in duplicate for oxygen content with a blood gas analyzer. Qs/Qt was calculated using the classic shunt equation. Statistical analysis was performed by analysis of variance of repeated measures of Qs/Qt and maternal position. The relationship of Qs/Qt to maternal cardiac output was evaluated by the correlation coefficient. Significance was defined as P < .05. RESULTS: Directly measured Qs/Qt averaged 15.3% in left lateral, 15.2% in right lateral, 13.9% in supine, 12.8% in knee-chest, 13.8% in sitting, and 13.0% in standing positions. There was no statistically significant correlation between Qs/Qt and cardiac output (R2 = 0.11, not significant). CONCLUSION: This is the first report of directly measured Qs/Qt in normal pregnant women in the third trimester. Qs/Qt values reported in pregnancy are higher than those reported in nonpregnant individuals.     

Effects of carperitide (alpha-human atrial natriuretic peptide) on acute congestive heart failure in dogs

Effects of carperitide (alpha-human atrial natriuretic peptide) on hemodynamics and renal function in dogs with congestive heart failure (CHF) produced by volume expansion and ligation of the left anterior descending coronary artery were compared with those of various anti-heart failure agents (cardiotonic, vasodilator and diuretic). Carperitide (0.1-1 microgram/kg/min) dose-dependently decreased the elevated left ventricular end-diastolic pressure (LVEDP). No significant changes in cardiac contractility (LV dP/dtmax) and heart rate (HR) were noted, although cardiac output (CO) tended to reduce during the infusion of carperitide. Nitroglycerin (NG; 3 micrograms/kg/min) and furosemide (1 mg/kg) also decreased LVEDP, but the potency was less than that of carperitide. Sodium nitroprusside (SNP; 10 micrograms/kg/min) and dobutamine (10 micrograms/kg/min) caused a reduction in LVEDP and increased CO with an increase in HR. Hydralazine (H; 100 micrograms/kg/min) increased CO without reduction in LVEDP and induced a pronounced increase in HR. Double product (systolic blood pressure x HR), an index of myocardial oxygen consumption, was significantly reduced by carperitide, but significantly increased by DB and H. Carperitide, unlike NG, SNP, H and DB, increased urine volume and urinary electrolyte excretion. These results suggest that carperitide will be an useful therapeutic agent for the treatment of CHF.     

The effects of propofol, isoflurane, and sevoflurane on oxygenation and shunt fraction during one-lung ventilation

Propofol's effect on hypoxic pulmonary vasoconstriction during one-lung ventilation (OLV) has not been determined. Twenty patients who had long-term OLV for esophageal surgery were allocated randomly to one of two study groups; one in which isoflurane administration preceded propofol, and another in which sevoflurane administration preceded propofol. Arterial and mixed venous blood samples and hemodynamics were measured as follows: before OLV, during OLV, OLV at 4 cm of positive end-expiratory pressure (PEEP), OLV after conversion from volatile anesthetics to propofol, OLV at 4 cm of PEEP, and after OLV. After the application of 4 cm of PEEP during propofol anesthesia, PaO2 increased significantly in both groups. The shunt fraction (Qs/Qt) increased significantly after the initiation of OLV in both groups and decreased significantly after the conversion from volatile anesthetics to propofol in both groups. Propofol can be used safely during OLV because PaO2 increased after the application of 4 cm of PEEP during propofol anesthesia, and Qs/Qt decreased significantly after the conversion from inhaled anesthetics to propofol anesthesia. IMPLICATIONS: During one-lung ventilation, the arterial partial pressure of oxygen values with propofol were greater than those with isoflurane and sevoflurane, and shunt fraction values with propofol were lower than those with both volatile anesthetics. Propofol improved oxygenation and shunt fraction during one-lung ventilation compared with volatile anesthetics.     

Peripheral vascular versus direct cardiac effects of calcium

Peripheral vascular and direct cardiac effects of calcium chloride were determined in a new animal model, the unanesthetized calf, before and after replacement of its natural heart (NH) with a pneumatically driven artificial heart (AH). Calcium (5 and 10 mg/kg) significantly increased cardiac output (Qt) and reduced systemic vascular resistance (SVR) before and after AH implantation. Increases in Qt in AH calves and reductions in SVR in both NH and AH calves were, however, transient, being present 5 minutes but not 15 minutes after both doses of calcium. Increases in Qt and reductions in SVR were significantly (P less than .05) greater after 10 mg/kg than after 5 mg/kg calcium in NH and AH calves. Both doses of calcium produced greater (P less than .05) increases of Qt in NH than in AH animals but similar reductions in SVR. Pulmonary vascular resitance, heart rate and pulmonary arterial and right atrial pressures were not significantly altered by either dose of calcium in NH or AH calves. Mean aortic pressure was influenced by 10 mg/kg calcium only, being transiently reduced in AH calves and increased in NH animals. Pulmonary shunt (QS/Qt) was increased by both doses of calcium in NH calves but only by 10 mg/kg in AH animals. Correlations of mean change in QS/Qt with mean change in Qt were high both before (r=.99) and after (r=.97) AH implantation. These data demonstrate that calcium significantly reduces SVR in a dose-related manner as well as exerting a positive inotropic effect on the myocardium.     

The neurotrophic analogue of ACTH(4-9) reduces the perineuronal microglial reaction after rat facial nerve crush

Rats bled to a severe condition of volume-controlled hemorrhagic shock were randomly assigned to one of the following treatments: (1) saline, 1 ml/kg i.v.; (2) saline, 0.2 ml/kg per min i.v. for 10 min; (3) ACTH-(1-24), 160 micrograms/kg i.v.; 4) methylprednisolone, 40 mg/kg i.v.; (5) methylprednisolone, 80 mg/kg i.v.; (6) aprotinin, 10,000 KIU/kg i.v.; (7) norepinephrine, 5 micrograms/kg per min i.v. for 10 min; (8) norepinephrine, 10 micrograms/kg per min i.v. for 10 min. All rats treated with saline or with either of the two doses of methylprednisolone, and half of the rats treated with aprotinin, died within the subsequent 2 h. On the other hand, rats treated with norepinephrine, at either dose, or with ACTH-(1-24) were all still alive 2 h later, a similar improvement in cardiovascular and respiratory parameters being obtained with the two treatments. The effect of ACTH on mean arterial pressure was however more sustained throughout the observation period. These results further support the potential usefulness of ACTH-(1-24) as first-aid treatment in cases of severe blood losses.     

Midazolam in the treatment of status epilepticus in children

OBJECTIVE: To determine the efficacy and safety of midazolam given as a continuous infusion in the treatment of status epilepticus in children. DESIGN: Prospective, open study. SETTING: Pediatric intensive care unit. PATIENTS: Twenty-four children with seizures, in whom three repeated intravenous doses of 0.3 mg/kg of diazepam, 20 mg/kg of phenobarbital, and 20 mg/kg of phenytoin failed to bring the episode under control. INTERVENTIONS: All patients received a bolus of midazolam (0.15 mg/kg iv) followed by a continuous infusion at 1 microgram/kg/min. The dose was increased every 15 mins until the episode of seizure was brought under control. Time to control seizures, infusion rate, and side-effects were monitored. MEASUREMENTS AND MAIN RESULTS: The mean age of the patient population was 2.2 yrs (range 2 months to 12 yrs; 14 female and 10 male). In all patients, seizures were controlled in a mean time of 0.78 hrs (range 15 mins to 4.5 hrs). The mean infusion rate was 2.3 micrograms/kg/min (range 1 to 18). None of the patients had clinically important changes in blood pressure, heart rate, oxygen saturation, or respiratory status attributable to the use of midazolam. The mean time to full consciousness for patients after stopping the infusion was 4.2 hrs (range 2 to 8.5). CONCLUSION: Midazolam is an effective and safe drug to control refractory seizures in children with status epilepticus.     

Use of a new Russian antihypertensive drug dilazin in surgery of the coronary arteries and abdominal aorta

Dilazin in a dose of 0.2 mg/kg/min (n = 20) and 0.4 mg/kg/min (n = 20) was used to normalize arterial blood pressure during and after surgery. Intravenous infusion of the drug decreased the arterial pressure to baseline values within 2-3 min by reducing the elevated systemic vascular resistance. Dilazin did not affect the heart rate, mean pulmonary capillary wedge pressure, or central venous pressure. The drug brought about a marked increase of cardiac output and cardiac index. Prompt effect and easy control, when dilazin is infused in a dose of 0.2 to 0.4 mg/kg/min, recommend it as an alternative antihypertensive agent to be used during various procedures.     

Modeling and measurement of the spontaneous mutation rate in mammalian cells

In order to examine the respiratory effects of tonic-clonic seizures and their treatment with i.v. diazepam or lorazepam, we utilized a spontaneously breathing piglet seizure model. A tracheostomy, arterial catheter, and epidural electrodes were inserted and pigs were maintained under ketamine anesthesia. After baseline recordings, seizures were induced with a pentylenetetrazol (PTZ) bolus and a 20 min infusion (5-6 mg/kg/min). After 10 min of PTZ infusion, randomly assigned animals received diazepam (D; N = 7; 0.5 mg/kg), lorazepam (L; N = 7; 0.2 mg/kg), or 0.9% saline (C; N = 7; controls) by rapid peripheral vein injection. Minute ventilation (Ve), Pa(CO2), and the pressure change in response to airway occlusion at end-expiration (P0.1) were measured at standard intervals. All groups had comparable increases in respiratory drive during untreated seizures. Changes in Ve and P0.1 were reduced to at or below baseline values in groups D and L, but not C, from 2 to 45 min after treatment (P < 0.05). No significant changes were observed in Pa(CO2) after either intervention. Following anticonvulsants, the cumulative duration of seizures was significantly reduced in L and D groups, compared to C (P < 0.05). We conclude that increases in respiratory drive occur during tonic-clonic seizures induced with PTZ. Amelioration of seizure activity with lorazepam or diazepam results in a reduction in respiratory drive, but not respiratory failure, in this tracheostomized model.     

Traumatic uveitis: the problem of pathogenetic therapy

Inhalative nitric oxide (NO) has recently been included in the therapeutic armament for the treatment of ARDS. We evaluated the effect of inhalative NO on hemodynamic and oxygen transport parameters in 30 internal intensive care patients suffering from ARDS. All patients received a pulmonary artery catheter. Hemodynamics were assessed prior to NO therapy and after 1, 6, 12, and 24 h. 80% (n = 24) of the patients were classified as therapy responders. The median NO dose was 15 ppm (range 5 to 40 ppm). The PaO2/FiO2--ratio increased significantly after initiation of NO (p = 0.0002) while the pulmonary shunt fraction (Qs/Qt) decreased significantly (p = 0.0019). All other measured or calculated parameters including arterial and pulmonary arterial blood pressure remained unchanged. No negative effects of the therapy could be observed. Inhalative NO improves oxygenation in most intensive care patients with ARDS and thus offers the possibility to reduce invasiveness of mechanical ventilation.     

Pulmonary shunting during anesthesia with deliberate hypotension

Pulmonary shunting (Qs/Qt with FIO2 = 1) was measured in 18 anesthetized patients during deliberate hypotension. Hypotension was induced in 12 patients with sodium nitroprusside and light halothane anesthesia and in six others with deep halothane anesthesia and mechanical hyperventilation. Similar results were observed in the two groups. During the hypotensive period mean arterial pressure (MAP) was reduced to 49 +/- 2 torr, a 37 per cent decrease from the control level after the onset of operation and a 40 per cent decrease compared with the recovery level during closure of the wound. Qs/Qt, however, remained unchanged throughout the study: 5.2 +/- 0.9 per cent initially, 5.4 +/- 0.8 per cent during hypotension, and 4.7 +/- 0.5 per cent during recovery. It is concluded that pulmonary shunting need not develop during deliberate hypotension induced with either technique.     

Stellettamide B, a new indolizidine alkaloid from a sponge of the genus Stelletta

BACKGROUND: The availability of nasal mask bi-level positive airway pressure (BiPAP) support in managing respiratory failure following cardiovascular surgery was studied. MATERIALS AND METHODS: BiPAP support was used for eight patients requiring postoperative prolonged respiratory support of 72 hours or longer. Their mean age was 65 years of age and the mean periods of postoperative endotracheal intubation was 12+/-5 days. BiPAP support was removed within 48 hours in six out of eight patients. Reintubation of an endotracheal tube was not necessary in all eight patients after the BiPAP treatment. RESULTS: The respiratory rates during the BiPAP management remained unchanged. The values of the respiratory index significantly (p<0.01) improved after BiPAP management (1.5+/-0.2 --> 0.9+/-0.2). A-aDO2 and Qs/Qt decreased (p<0.1) after the BiPAP management. There were no significant differences in central venous pressure and circulatory states during BiPAP support. CONCLUSIONS: In conclusions, BiPAP support is a noninvasive management technique for postoperative respiratory failure and may also prevent prolonged endotracheal intubation.     

Hemodynamic effects of angiotensin II and the influence of angiotensin receptor antagonists in pithed rabbits

We investigated the cardiovascular effects of angiotensin II (AII) and the influences of four angiotensin receptor antagonists: losartan, PD123177, BIBS 39, and BIBS 222 in the pithed rabbit preparation. AII (0.03-10 nmol/kg) elicited a dose-dependent increase in blood pressure (BP), left ventricular pressure (LVP), LV end-diastolic pressure (LVEDP), dP/dtmax, and heart rate (HR). The maximal hypertensive effect of AII is comparable to that of norepinephrine (NE), but its effects on LVEDP and HR are weaker than those of NE. On a molar base, AII is approximately 27 times more potent than NE. Propranolol (0.5 mg/kg i.v.) did not significantly influence the AII-induced increase in diastolic BP (DBP) and LVEDP, but it abolished AII-induced positive chronotropic effects over the entire dose range of angiotensin AII studied. Losartan, but not PD123177, shifted the dose-response curves for AII to the right in a parallel manner. BIBS 39 and BIBS 222 also caused rightward shifts of the AII dose-response curve. These experiments indicate that in propranolol-treated pithed rabbits AII causes vasoconstrictor effects in both resistance vessels and in the venous system, which are both mediated by AT1- but not by AT2-receptors. The AII-induced positive chronotropic effect is an indirect action mediated by the stimulation of postsynaptic beta 1-adrenoceptors. BIBS 39 and BIBS 222, two new nonpeptide angiotensin receptor blockers that have affinity for both AT1- and AT2-receptors are also potent antagonists of the cardiovascular effects of AII in pithed rabbits.     

Comparison of haemodynamic responses to cilnidipine and nicardipine in an experimental model of acute congestive heart failure

1. The haemodynamic effects of cilnidipine, a new calcium channel blocker, were examined in a canine model of acute congestive heart failure and were compared with those of nicardipine at equihypotensive doses. 2. The model was prepared by injections of saponin into coronary arteries of anaesthetized open-chest dogs followed by volume loading and continuous i.v. infusion of methoxamine. After the treatment, aortic blood flow (AoF) and left ventricular dP/dt markedly decreased, while left ventricular end-diastolic pressure (LVEDP), right atrial pressure and systemic vascular resistance (SVR) increased. Cilnidipine (0.3, 1.0 and 3.0 micrograms/kg per min), nicardipine (0.3, 1.0 and 3.0 micrograms/kg per min) or the respective vehicle was given i.v. after accomplishment of heart failure. 3. These drugs both produced a comparable reduction in aortic pressure and an increase in AoF associated with profound decreases in LVEDP, SVR and coronary vascular resistance. In contrast, administration of nicardipine was associated with significant increases in heart rate and cardiac contractility but that of cilnidipine was not. 4. These results indicate that cilnidipine as well as nicardipine can exert beneficial haemodynamic effects in a model of acute heart failure probably through lessening afterload and cilnidipine may moderate reflex-induced sympathetic stimulation.     

Intravenous nitroglycerin in acute respiratory failure of patients with chronic obstructive lung disease, secondary pulmonary hypertension and cor pulmonale

We have studied the hemodynamic effects of an intravenous single dose of nitroglycerin in 13 patients with secondary pulmonary hypertension and Cor Pulmonale, during the acute course of respiratory failure and under assisted ventilation. We observed a significant decrease in systolic, diastolic and mean pulmonary arterial pressures, and in pulmonary resistance and systolic right ventricular work index, without any change in right or left pre-loads. The systolic arterial pressure decreased slightly, without any change in cardiac index or diastolic pressure. The arterial and mixed venous oxygen contents, and the pulmonary shunting ( Qs/Qt) were unchanged. These results suggest that nitroglycerin may be a useful therapy in patients in the acute stages of pulmonary hypertension resulting from chronic lung disease and under assisted ventilation. In addition, the lack of change in cardiac index, intrapulmonary shunting and oxygen content suggests that this decrease in pulmonary resistance is not linked with any deleterious effect in oxygen transfer.     

Pulmonary hemodynamics and plasma endothelin-1 during hypoxemia and reoxygenation with room air or 100% oxygen in a piglet model

The immediate effect on the pulmonary circulation of reoxygenation with either room air or 100% O2 was studied in newborn piglets. Hypoxemia was induced by ventilation with 8% O2 until base excess was <-20 mmol/L or mean arterial blood pressure was <20 mm Hg. Reoxygenation was performed with either room air (n = 9) or 100% O2 (n = 9). Mean pulmonary artery pressure increased during hypoxemia (p = 0.012). After 5 min of reoxygenation, pulmonary artery pressure increased further from 24 +/- 2 mm Hg at the end of hypoxemia to 35 +/- 3 mm Hg (p = 0.0077 versus baseline) in the room air group and from 27 +/- 3 mm Hg at the end of hypoxemia to 30 +/- 2 mm Hg (p = 0.011 versus baseline) in the O2 group (NS between groups). Pulmonary vascular resistance index increased (p = 0.0005) during hypoxemia. During early reoxygenation pulmonary vascular resistance index decreased rapidly to values comparable to baseline within 5 min of reoxygenation in both groups (NS between groups). Plasma endothelin-1 (ET-1) decreased during hypoxemia from 1.5 +/- 0.1 ng/L at baseline to 1.2 +/- 0.1 ng/L at the end of hypoxemia (p = 0.003). After 30 min of reoxygenation plasma ET-1 increased to 1.8 +/- 0.3 and 1.5 +/- 0.2 ng/L in the room air and O2 groups, respectively (p = 0.0077 in each group versus end hypoxemia; NS between groups). We conclude that hypoxemic pulmonary hypertension and plasma ET-1 normalizes as quickly when reoxygenation is performed with room air as with 100% O2 in this hypoxia model with newborn piglets.     

Characteristics of vascular wall cells subjected to dynamic cyclic strain and fluid shear conditions in vitro

Surfactant bolus instillation may be associated with a drop in blood pressure. Platelet-activating factor (PAF) has been found in surfactant preparations. The aim of this study was to evaluate rapid tracheal infusion of surfactant during 5 min as an alternative to bolus instillation and to examine whether a PAF receptor antagonist is able to prevent the decrease in blood pressure. METHODS: Surfactant deficiency was induced in 16 adult rabbits by lung lavages with saline. Six animals received a bolus of a porcine surfactant preparation (Curosurf (CS); 200 mg/kg), labeled with red microspheres to assess pulmonary distribution. In another 5 rabbits, the same amount of labelled CS was instilled by tracheal infusion within 5 min. A third group of 5 animals received 3 mg/kg body weight of the PAF antagonist WEB 2170 before CS bolus instillation. RESULTS: After CS bolus administration, mean PaO2 increased by 44.7 +/- 8.3 kPa (mean +/- SD) within 2 min and remained at this level. Mean arterial blood pressure dropped transiently by 2.3 +/- 2 kPa within 5 min. Pulmonary distribution of surfactant was even. After infusion, mean PaO2 rose by 22.4 +/- 16.3 kPa within 15 min. Blood pressure dropped by 1.8 +/- 1.1 kPa within 15 min. The distribution was extremely uneven. Blood pressure decreases also occurred after pretreatment with PAF receptor antagonist. CONCLUSION: Rapid tracheal infusion of surfactant results in poorer oxygenation, an inhomogeneous distribution and a similar decrease in blood pressure compared to the bolus instillation method. Blood pressure changes could not be prevented by a PAF receptor-specific antagonist.     

Focal epithelial hyperplasia in an HIV positive man. An illustrated case and review of the literature

Chickens 14 days old were experimentally inoculated with Mycoplasma gallisepticum (MG) R-P10 strain. After development of respiratory symptoms, birds were left unmedicated or medicated for 5 consecutive days with Difloxacin 5, 7.5 or 10 mg/kg body weight per day or Enrofloxacin at the dose level of 10 mg/kg body weight per day. Evaluation of efficacy was based on body weight, symptoms, post-mortem findings, re-isolation of MG and serology. Results indicated that under the conditions of this experiment, treatment with 7.5 mg Difloxacin per kg body weight for 5 days was already effective against pathogenic MG infection. The dose of 10 mg/kg Difloxacin was equally effective as a dose of 10 mg/kg Enrofloxacin in treating respiratory symptoms.     

cAMP analogues downregulate the expression of granulocyte macrophage colony-stimulating factor (GM-CSF) in human bone marrow stromal cells in vitro

STUDY OBJECTIVE: To determine the neuromuscular blocking effect and recovery profile of cisatracurium besylate in children after administration of a bolus dose that was twice the estimated dose required to produce 95% of the maximum effect (2 x ED95; 0.08 mg/kg) followed by an infusion during halothane-nitrous oxide anesthesia. STUDY DESIGN: Open-label study. SETTING: Teaching hospital. PATIENTS: 30 male and female (ASA physical status I and II) patients, 2 to 10 years of age, scheduled for elective surgery of low to moderate risk. INTERVENTIONS: After induction of general anesthesia, patients received cisatracurium 0.08 mg/kg administered over 5 to 10 seconds. For surgical procedures requiring neuromuscular block for at least 60 minutes, a second bolus dose of cisatracurium 0.02 mg/kg was administered after the first response to a train-of-four stimuli (T1) recovered to 25% of baseline. When T1 was 5% of baseline after the second dose, a 3 microg/kg/min infusion of cisatracurium was initiated and titrated to maintain 89% to 99% block for the duration of the surgery. For procedures requiring neuromuscular block of less than 60 minutes, one or more maintenance doses of 0.02 mg/kg cisatracurium were administered when T1 was 25% of baseline after the preceding dose. In 10 patients, recovery was facilitated with edrophonium 1.0 mg/kg administered when T1 was 26% to 48% of the final baseline. MEASUREMENTS AND MAIN RESULTS: Evoked muscular response at the adductor pollicis was measured by electromyography. With 0.08 mg/kg, onset time (mean +/- SEM) was 4.1 +/- 0.4 minutes, and clinically effective duration was 27.3 +/- 0.9 minutes. Mean 5% to 95% and 25% to 75% recovery indices were 28.4 +/- 2. 7 minutes and 11.2 +/- 0.8 minutes, respectively. The mean infusion rate necessary to maintain 89% to 99% T1 suppression for 17 to 145 minutes was 1.7 microg/kg/min. After termination of infusion, the mean 5% to 95% and 25% to 75% recovery indices were similar to those after a single bolus dose, and time to 95% recovery was 30.4 +/- 3.0 minutes. After administration of edrophonium, full recovery (T4:T1 > or = 70%) occurred in 1.5 +/- 0.4 minutes. No clinically significant changes in heart rate or blood pressure were noted during the first 5 minutes after administration of cisatracurium 0.08 mg/kg. CONCLUSIONS: Cisatracurium provided maximal neuromuscular block, cardiovascular stability, and predictable recovery at the doses tested. In view of this finding, cisatracurium should be a useful intermediate-duration neuromuscular blocking drug for children during general anesthesia.     

The rate of force generation by the myocardium is not influenced by afterload

The influence of afterload on the rate of force generation by the myocardium was investigated using two types of preparations: the in situ dog heart (dP/dt) and isolated papillary muscle of rats (dT/dt). Thirteen anesthetized, mechanically ventilated and thoracotomized dogs were submitted to pharmacological autonomic blockade (3.0 mg/kg oxprenolol plus 0.5 mg/kg atropine). A reservoir connected to the left atrium permitted the control of left ventricular end-diastolic pressure (LVEDP). A mechanical constriction of the descending thoracic aorta allowed to increase the systolic pressure in two steps of 20 mmHg (conditions H1 and H2) above control values (condition C). After arterial pressure elevations (systolic pressure C: 119 +/- 8.1; H1: 142 +/- 7.9; H2: 166 +/- 7.7 mmHg; P < 0.01), there were no significant differences in heart rate (C: 125 +/- 13.9; H1: 125 +/- 13.5; H2: 123 +/- 14.1 bpm; P > 0.05) or LVEDP (C: 6.2 +/- 2.48; H1: 6.3 +/- 2.43; H2: 6.1 +/- 2.51 mmHg; P > 0.05). The values of dP/dt did not change after each elevation of arterial pressure (C: 3,068 +/- 1,057; H1: 3,112 +/- 996; H2: 3,086 +/- 980 mmHg/s; P > 0.05). In isolated rat papillary muscle, an afterload corresponding to 50% and 75% of the maximal developed tension did not alter the values of the maximum rate of tension development (100%: 78 +/- 13; 75%: 80 +/- 13; 50%: 79 +/- 11 g mm-2 s-1, P > 0.05). The results show that the rise in afterload per se does not cause changes in dP/dt or dT/dt.