Increasing the injection volume by dilution improves the onset of motor blockade, but not sensory blockade of ropivacaine for brachial plexus block.

BACKGROUND AND OBJECTIVE: Ropivacaine used for axillary plexus block provides effective motor and sensory blockade. Varying clinical dosage recommendations exist. Increasing the dosage by increasing the concentration showed no improvement in onset. We compared the behaviour of a constant dose of ropivacaine 150 mg diluted in a 30, 40 or 60 mL injection volume for axillary (brachial) plexus block. METHODS: A prospective, randomized, observer-blinded study on patients undergoing elective hand surgery was conducted in a community hospital. Three groups of patients with a constant dose of ropivacaine 150 mg, diluted in 30,40 or 60 mL NaCl 0.9%, for axillary plexus blockade were compared for onset times of motor and sensory block onset by assessing muscle strength, two-point discrimination and constant-touch sensation. RESULTS: Increasing the injection volume of ropivacaine 150 mg to 60 mL led to a faster onset of motor block, but not of sensory block, in axillary plexus block, compared with 30 or 40 mL volumes of injection. CONCLUSIONS: The data show that the onset of motor, but not of sensory block, is accelerated by increasing the injection volume to 60 mL using ropivacaine 150 mg for axillary plexus block. This may be useful for a more rapid determination of whether the brachial plexus block is effective. However, when performing surgery in the area of the block, sensory block onset seems more important.

Remifentanil or propofol for sedation during carotid endarterectomy under cervical plexus block.

BACKGROUND: During carotid endarterectomy under regional anaesthesia, patients often require medication to control haemodynamic instability and to provide sedation and analgesia. Propofol and remifentanil are used for this purpose. However, the benefits, side-effects, and optimal dose of these drugs in such patients are unclear. METHODS: Sixty patients were included in a prospective, randomized, single blinded study. All patients received a deep cervical plexus block with 30 ml ropivacaine 0.75% and were randomized to receive either remifentanil 3 micro g kg(-1) h(-1) or propofol 1 mg kg(-1) h(-1). The infusions were started after performing the regional block and were stopped at the end of surgery. Arterial pressure, ECG, ventilatory rate, and Pa(CO(2)) were measured continuously and recorded at predetermined times. Twenty-four hours after surgery, patient comfort, and satisfaction were also evaluated. RESULTS: In three patients, the infusion of remifentanil had to be stopped because of severe respiratory depression or bradycardia. No significant differences were found between the two groups in haemodynamic variables or sedative effects, but there was a significantly greater decrease in ventilatory frequency and increase in Pa(CO(2)) in the remifentanil group. The patient's subjective impressions and pain control were excellent in both groups. CONCLUSION: As a result of the higher incidence of adverse respiratory effects with remifentanil and similar sedative effects, propofol is preferable for sedation during cervical plexus block in elderly patients with comorbid disease at the dosage used.

Waste gas exposure to sevoflurane and nitrous oxide during anaesthesia using the oesophageal-tracheal Combitube small adult.

Exposure to sevoflurane (SEV) and nitrous oxide during ventilation using a Combitube (37Fr) small adult (SA) was compared with waste gas exposure using conventional endotracheal tubes. Trace concentrations of SEV and nitrous oxide were assessed using a direct reading spectrometer during 40 gynaecological laparoscopic procedures under general anaesthesia. Measurements were made at the patients' mouth and in the anaesthetists' breathing zone. Mean (SD) concentrations of SEV and nitrous oxide measured at the patients' mouth were comparable in the Combitube SA (SEV 0.6 (0.2) p.p.m.; nitrous oxide 9.7 (8.5) p.p.m.) and endotracheal tube group (SEV 1.2 (0.8) p.p.m.; nitrous oxide 17.2 (10.6) p.p.m.). These values caused comparable contamination of the anaesthetists' breathing zone (SEV 0.6 (0.2) p.p.m. and nitrous oxide 4.3 (3.7) p.p.m. for the Combitube SA group, compared with SEV 0.5 (0.2) p.p.m. and nitrous oxide 4.1 (1.8) p.p.m. for the endotracheal tube group). We conclude that the use of the Combitube SA during positive pressure ventilation is not necessarily associated with increased waste gas exposure, especially when air conditioning and scavenging devices are available.

Nalbuphine by PCA-pump for analgesia following hysterectomy: bolus application versus continuous infusion with bolus application.

The analgesic properties of the partial agonist-antagonist nalbuphine in the postoperative period are well known. When used for patient-controlled analgesia (PCA) the effectiveness of this substance is comparable to that of morphine or tramadol. However, the optimal programme for administration of nalbuphine in PCA-pumps has not been investigated. In particular, the combination of bolus administration vs bolus administration plus continuous basal administration is disputable. We hypothesized that the administration of an extra basal rate of nalbuphine in addition to the patient- triggered bolus administration and supplemental doses of diclofenac when required, would lead to a significant improvement in analgesia, without affecting the differences in vital signs and side effects. After approvement by the institutional ethics committee, 50 female patients (ASA I or II) scheduled for elective hysterectomy were included in a prospective, single-blinded study and randomized either into bolus-continuous (BC-)group (3 mg base rate/h, 1 mg bolus, 20 min lock out) or bolus (B-)group (no base rate, 1 mg bolus, 10 min lock out). During the observation period (up to 24 h postoperative) vital parameters, extent of analgesia (10-step VAS), and vigilance (5-step scale) were registered. Groups were compared by using unpaired Student t-test. A p<0.05 was considered to be significant. No differences were found in demographic data or vital parameters (MAP, PaO2, PaCO2, respiratory rate, heart rate, peripheral SaO2) during the observation period. Vital parameters showed no pathological changes in any group. With an identical rate of requirement for diclofenac (32 and 36%), analgesia in BC-group showed a decrease in VAS from 4.28+/-2.11 to 2.04+/-1.21 and from 3.64+/-2.20 to 2.08+/-0.96 in B-group. Vigilance was only marginally diminished in both groups. No serious side effects were found in either group. The consumption of nalbuphine (mg) was significantly higher in BC-group (70.28+/-13.85 vs. 47.44+/-22.99;p =0.0002) when compared to B-group. Subjective rating of effectiveness by the patients was similar in both groups. The two administration settings of nalbuphine by PCA pump have shown to be equally effective in the treatment of postoperative pain following hysterectomy. However, as the total amount of nalbuphine was significantly lower in B-group, the use of this administration schedule should be encouraged.

Naloxone-resistant respiratory depression and neurological eye symptoms after intrathecal morphine.

We describe a case of neurological symptoms after the intrathecal use of an opioid. These symptoms were not reversible by the use of an opioid-antagonist.

Influence of positive airway pressure on the pressure gradient for venous return in humans.

To study the effect of positive airway pressure (Paw) on the pressure gradient for venous return [the difference between mean systemic filling pressure (Pms) and right atrial pressure (Pra)], we investigated 10 patients during general anesthesia for implantation of defibrillator devices. Paw was varied under apnea from 0 to 15 cmH(2)O, which increased Pra from 7.3 +/- 3.1 to 10.0 +/- 2.3 mmHg and decreased left ventricular stroke volume by 23 +/- 22%. Episodes of ventricular fibrillation, induced for defibrillator testing, were performed during 0- and 15-cmH(2)O Paw to measure Pms (value of Pra 7.5 s after onset of circulatory arrest). Positive Paw increased Pms from 10.2 +/- 3.5 to 12.7 +/- 3.2 mmHg, and thus the pressure gradient for venous return (Pms - Pra) remained unchanged. Echocardiography did not reveal signs of vascular collapse of the inferior and superior vena cava due to lung expansion. In conclusion, we demonstrated that positive Paw equally increases Pra and Pms in humans and alters venous return without changes in the pressure gradient (Pms - Pra).

[Course of the progression of experimentally induced arteriosclerotic vessel wall changes after treatment with magnesium orotate] . / Progressionsverlauf experimentell ausgelöster arteriosklerotischer Gefässwandveränderungen nach Behandlung mit Magnesiumorotat.

There are some experimental and clinical results regarding blood vessel protective properties of magnesium orotate (CAS 27067-77-2) till now. The goal of the present investigation was to verify the therapeutical efficacy of magnesium orotate vs. its singular components in cholesterol fed rabbits. Besides, the blood-lipid concentrations (LDL as risk factor for atherosclerosis and HDL as negative risk factor) were analyzed in relation to pathomorphological changes in the aortic blood vessel wall. The results of our experiments in New Zealand rabbits support the assumption that orotic acid and especially magnesium orotate influence the lipid level and/or the LDL/HDL-quotient in a favorable way and that they decrease the interaction between monocytes/macrophages and the endothelium of the blood vessels. Consequently, the plaque formation will be decreased in a clinically relevant manner.

Right atrial pressure predicts hemodynamic response to apneic positive airway pressure.

OBJECTIVE: To evaluate if the preexistant filling state, assessed by right atrial pressure (RAP), pulmonary artery occlusion pressure (PAOP), and right ventricular end-diastolic volume index (EDVI), would define the subsequent hemodynamic effects of increases in airway pressure (Paw). DESIGN: Prospective open clinical study. SETTING: Postoperative intensive care unit, university hospital. PATIENTS: Twenty-two consecutive ventilator-dependent patients with mild to severe acute lung injury with Murray scores (scoring infiltrates on chest radiograph, oxygenation index, lung compliance, and the level of positive end-expiratory pressure) ranging from 0.5 to 3.0 without history of preexisting cardiopulmonary disease. INTERVENTIONS: Paw varied during apnea from 0 to 10, 20, and 30 cm H2O using inspiratory hold maneuvers of 15 secs. MEASUREMENTS AND MAIN RESULTS: Cardiac index and right ventricular ejection fraction were measured by the thermodilution technique. We made measurements in triplicate using manual injection of iced saline. Right ventricular volumes were calculated. Increasing Paw induced variable changes in cardiac index among subjects (+6% to -43% change from baseline 0 cm H2O Paw values), which correlated with percentage changes in both stroke index (r2 = .89) and right ventricular EDVI (r2 = .75), whereas heart rate and right ventricular ejection fraction did not change. The change in cardiac index from 0 to 30 cm H2O Paw correlated with baseline values for RAP, PAOP, and right ventricular EDVI (r2 = .68, .43, and .34, respectively, p < 0.01). Increases in RAP correlated with lung compliance if baseline RAP was >10 mm Hg but did not if it was < or =10 mm Hg. Similarly, patients with baseline RAP < or =10 mm Hg had a greater decrease in cardiac index than patients with a RAP >10 mm Hg (for 30 cm H2O Paw: -30% +/- 9% vs. -8% +/- 7%, p < .01). CONCLUSIONS: Apneic positive Paw decreased cardiac output mainly by reducing venous return. From the investigated filling variables, RAP was most sensitive in predicting the hemodynamic response, followed by PAOP and right ventricular EDVI. Patients with RAP < or =10 mm Hg, if subjected to aggressive positive pressure ventilation, are at risk of hemodynamic deterioration and organ hypoperfusion.

Hemodynamic and catecholamine stress responses to insertion of the Combitube, laryngeal mask airway or tracheal intubation.

UNLABELLED: In a prospective, randomized, and controlled trial, we compared the stress responses after insertion of the Combitube (CT; Kendall-Sheridan Catheter Corp., Argyle, NY), the laryngeal mask airway (LMA), or endotracheal intubation (ET). Seventy-five patients scheduled for routine urological or gynecological surgery were randomly allocated to one of three groups and were ventilated via either an ET, a LMA, or a CT. All three devices could be inserted easily and rapidly, providing adequate ventilation and oxygenation. Insertion of the CT was associated with a significant increase in mean maximal systolic arterial pressure (160+/-32 mm Hg) and diastolic arterial pressure (91+/-17 mm Hg) compared with ET (140+/-24, 78+/-11 mm Hg; P < 0.05, P < 0.01, respectively) or insertion of the LMA (115+/-33,63+/-22 mm Hg, both P < 0.001). The mean maximal epinephrine and norepinephrine plasma concentrations after insertion of the CT (37.3+/-31.1 and 279+/-139 pg/mL, respectively) were significantly higher than those after ET (35.8+/-89.8 and 195+/-58 pg/mL, respectively) or insertion of a LMA (17.3+/-13.3 and 158+/-67 pg/mL, respectively). This might be attributed to the pressure of the pharyngeal cuff of the CT on the anterior pharyngeal wall. We conclude that insertion of the CT causes a pronounced stress response and that precautions should be taken when used in patients at risk of hypertensive bleeding. IMPLICATIONS: In this study, we showed that the hemodynamic and catecholamine stress responses after insertion of the Combitube (Kendall-Sheridan Catheter Corp., Argyle, NY) were significantly higher compared with laryngeal mask airway or endotracheal intubation. We conclude that the increased stress response to insertion of a Combitube may represent a serious hazard to patients with cardiovascular disease.

[Morphological aspects of the effect of magnesium orotate therapy on changes in the vascular walls induced by cholesterol-rich diet]. / A magnézium-orotát terápia hatásának morfológiai aspektusai koleszterindús diéta nyomán kialakult érfali elváltozásokban.

Heart and blood vessel disease are one of the leading causes of death, so their prevention and therapy are very important. In the present study the effects of magnesium chloride, magnesium orotate and orotic acid were tested. New Zealand rabbits were fed with enriched (2%) cholesterol diet during 112 days: starting with day 56 all rabbits were treated with MgCl2, Mg-orotate or orotic acid (orally). Aortas, coronaries, renal and femoral arteries were removed and evaluated by morphological and morphometric methods. Atherosclerotic alterations in each vessel could be influenced moderately by Mg-chloride, quite well by orotic acid and excellently by Mg-orotate. From these results one can conclude that orotic acid and Mg-orotate have a beneficial effect in the prevention and therapy of heart and vessels diseases.

Measurement of right ventricular performance during apnea in patients with acute lung injury.

BACKGROUND: Mechanical ventilation resulted in increased, decreased or unchanged end-diastolic volumes together with either profoundly decreased or unchanged right ventricular ejection fraction (RVEF). The goal of our study was, therefore, to evaluate the effects of positive end-expiratory pressure on measurements of RVEF performed during apneic periods with different levels of positive end-expiratory pressure. METHODS: Fifteen consecutive patients suffering from acute lung injury after major surgery or trauma were included. Measurements were performed during 15 seconds of apnea at airway pressure levels of 0 (baseline), 10, 20, and 30 cm H2O. Cardiac output and RVEF were determined using the thermodilution technique. RESULTS: Lung inflation to an airway pressure of 30 cm H2O caused a 22 +/- 14% decrease of cardiac output resulting from a 20 +/- 14% decrease of stroke volume index. The decrease of stroke volume index was induced by a 17 +/- 11% decrease of right ventricular end-diastolic volume index, while RVEF remained virtually unchanged (0.49 +/- 0.10 vs. 0.47 +/- 0.12 at 0 and 30 cm H2O, respectively). Relative changes of cardiac output were closely correlated with changes of right ventricular end-diastolic volume index (p < 0.05, r2 = 0.78). CONCLUSIONS: Right ventricular systolic function was well maintained despite substantially decreased end-diastolic volumes. In our study, during apneic conditions, higher levels of positive end-expiratory pressure did not worsen RVEF in patients with acute lung injury. The proposed technique of apneic lung inflation may serve as an alternative approach to obtain comparable measurements of RV function in patients with acute lung injury.

[Multiple organ failure with several weeks' persistence of ARDS: successful therapy with methylprednisolone]. / Mehrorganversagen mit mehrwöchiger Persistenz eines ARDS: Erfolgreiche Therapie mit Methylprednisolon.

A 21-year-old female who had developed ileus underwent abdominal surgery for adhesiolysis. Because of postoperative bleeding she required repeated surgical reexploration. Subsequently, the patient developed abdominal sepsis (Enterobacter cloacae) and, on day 11 of mechanical ventilation, severe adult respiratory distress syndrome (ARDS) (Lung injury score 3.5, paO2/FiO2 55 mmHg). Despite clearing the abdominal situation, chest films showed persisting and new pulmonary infiltrates, leucocytosis, fever and purulent bronchial secretion occurring over a period of five weeks. Despite aggressive antibiotic treatment the patient deteriorated further and disease progressed to multiple organ dysfunction syndrome. At the beginning of week six all bacteriological specimens (blood, bronchoalveolar lavage, urine, catheter tips) were negative for potential pathogens. Possible extrapulmonary infection sites were cleared by computed tomography and Tc 99 labeled antigranulocyte antibody scan. Open lung biopsy was performed on day 33 of ARDS and revealed severe diffuse alveolar damage in the fibroproliferative phase of ARDS. On day 37 after ARDS onset, antibiotic treatment was discontinued and methyl-prednisolone (32 mg every 6 hours, 2.5 mg/kg.day) was started. After five days a significant improvement of pulmonary function (lung injury score decreased from 3.5 to 2.5, paO2/FiO2 increased from 82 to > 200 mmHg) and of cardiovascular performance occurred. Corticosteroid treatment was continued for 29 days and was complicated by an episode of pneumonia (Klebsiella pneumoniae) requiring antibiotic therapy. The patient's trachea was successfully extubated on day 80. She was discharged from intensive care unit on day 93 and left hospital three weeks later. We conclude that late ARDS may cause systemic inflammatory response and persisting organ dysfunction without an identifiable source of infection. Corticosteroid therapy might improve fibroproliferative changes of the lung even if instituted weeks after the onset of ARDS.

Morphological aspects of the effects of orotic acid and magnesium orotate on hypercholesterolaemia in rabbits.

Heart and blood vessel diseases are one of the leading causes of death, so their prevention and therapy are very important. In the present study the effects of magnesium chloride, magnesium orotate and orotic acid were tested. New Zealand rabbits were fed with enriched (2%) cholesterol diet during 112 days; starting with day 56 all rabbits were treated with MgCl2, Mg-orotate or orotic acid (orally). Aortas, coronaries, renal and femoral arteries were removed and evaluated by morphological and morphometric methods. Atherosclerotic alterations in each vessel could be influenced moderately by Mg-chloride, quite well by orotic acid and excellently by Mg-orotate. From these results one can conclude that orotic acid and Mg-orotate have a beneficial effect in the prevention and therapy of heart and vessels diseases.

Coronary arteriopathy after lymphatic blockade: an experimental study in dogs.

The effects of lymph stasis on the histological and biochemical properties of the coronary arterial wall and on the coronary circulation were studied in 72 dogs. Cardiac lymph stasis was produced in 52 dogs by cardiac lymphatic blockade whereas in 20 dogs only a sham operation was performed. Blockade of cardiac lymph drainage promoted characteristic injury to the coronary arteries including subendothelial edema with plasma inbibition, interstitial and intracellular edema in the tunica media with degeneration in the smooth muscle layer, swelling of the adventitial space with dilated lymph vessels and, later, fibrosis. The biochemical properties of the coronary arterial wall also were adversely affected by cardiac lymph stasis. Thus, the collagen and hexosamine content of the coronary arteries increased and the metabolism of the coronary wall shifted in an anaerobic direction. Whereas coronary blood flow was slightly decreased with lymph blockade, the coronary circulatory reserve capacity and the adaptability of the coronary vascular system was markedly reduced. The histological changes were most apparent in the smaller coronary arteries. The coronary microvasculature was also pathologically altered with the development of numerous coronary arteriovenous microshunts. These findings in conjunction with other experimental and clinical information suggest that impaired cardiac lymph drainage contributes to the pathogenesis and progression of coronary artery disease.

Arterial to end-tidal CO2 tension difference after bilateral lung transplantation.

OBJECTIVES: To assess ventilation/perfusion mismatch with high ventilation/perfusion ratios (i.e., alveolar deadspace) and to assess capnography as a noninvasive method of monitoring ventilation after bilateral lung transplantation. DESIGN: Clinical, prospective study. Repeated-measures analysis of variance was done to assess the time course of the arterial to end-tidal CO2 tension difference. SETTING: University hospital operating theater and intensive care unit. PATIENTS: Seven consecutive patients aged 25 to 64 yrs who underwent bilateral lung transplantation for end-stage lung disease. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The arterial to end-tidal CO2 tension difference was determined using infrared absorption capnography during postoperative day 1. Measurements were done at 10 mins, and at 1, 3, 12, and 24 hrs after bilateral lung transplantation (timing of measurements determined from the time when both lungs were perfused and mechanically ventilated). An arterial to end-tidal CO2 tension difference, ranging from 6 to 21 torr (0.8 to 2.8 kPa), mean 16 +/- 5 torr (2.2 +/- 0.7 kPa), was observed immediately after the transplantation. This difference rapidly decreased to 9 +/- 4 torr (1.2 +/- 0.6 kPa; p < .01) after 3 hrs and to 5 +/- 3 torr (0.6 +/- 0.4 kPa; p < .01) after 24 hrs. CONCLUSIONS: Our data suggest marked alveolar deadspace ventilation immediately after bilateral lung transplantation. The presence and rapid improvement of this ventilation/perfusion mismatch may reflect the presence of ischemia-reperfusion lung injury and its improvement in the first hours of reperfusion. In five of seven patients, capnography was not a good measure of PaCO2 during the first hours after bilateral lung transplantation.

[Pseudo-faulty location of a Swan-Ganz catheter in a persistent left superior vena cava]. / Pseudo-Fehllage eines Swan-Ganz-Katheters bei V. cava superior sinistra persistens.

The insertion of a Swan-Ganz catheter may cause various complications including intravascular malpositioning due to congenital anomalies of the large veins. A persistent left superior vena cava is the most frequent anomaly of the large vessels. It is usually diagnosed either as an incidental finding at autopsy or during X-ray imaging for confirming proper position of central venous and pulmonary catheters. The incidence of this condition based on autopsy series is approximately 0.3%. CASE REPORT. A 52-year-old patient was admitted to the surgical ICU with the diagnosis of acute pancreatitis. Because of haemodynamic instability, a pulmonary artery flotation catheter was inserted via the left subclavian vein without difficult. The chest radiograph showed the catheter along the left border of the heart going into the right pulmonary artery. An angiographic examination with bolus contrast injection confirmed a persistent left superior vena cava. CONCLUSION. This type of malposition calls for further detailed diagnosis of the vascular status, as the knowledge of accompanying congenital cardiovascular defects is essential for further invasive diagnostic and surgical procedures. The intensivist should be aware of its occurrence in order to not mistake catheters as being present in the arterial circulation or malpositioned outside the venous circulation.

[A complete ventilation-perfusion mismatch following one-sided lung transplantation and postoperative hemothorax]. / Komplettes Ventilations-/Perfusionsmissverhältnis nach einseitiger Lungentransplantation und postoperativem Hämatothorax.

Eight days after single-lung transplantation for pulmonary hypertension, a patient presented with a hemothorax on the side of the transplanted lung that required acute thoracotomy. Pulmonary artery pressure had decreased from 78/32/58 mmHg prior to the transplant to 42/18/27 mmHg on the 2nd postoperative day. Therefore, a predominance of perfusion to the transplanted lung was expected. During induction of anesthesia, in spite of ventilation with pure oxygen the patient developed a hypoxic cardiac arrest (paO2 26 mmHg, 40% saturation measured by pulse oximetry) requiring external chest compression. Auscultation and chest movements suggested that the transplanted lung was not ventilated. Because blood flow went mainly to the transplanted lung, ventilation of the native lung was almost totally dead-space ventilation. To enable ventilation of the compressed transplanted lung, the patient was intubated using a single-lumen bronchial blocker tube to block the mainstem bronchus of the native lung. The transplanted lung could then be ventilated. Saturation increased and epinephrine re-established a stable circulation; 2500 ml blood were removed from the pleura without further complications. On the 7th postoperative day the patient was discharged from the intensive care unit without neurological deficits. A perfusion scan 28 days post-transplant revealed 89% of the perfusion going to the transplanted lung. Atelectasis of this lung resulted in a large intrapulmonary right-to-left shunt. Hypoxic pulmonary vasoconstriction could not ameliorate the shunt because of the high pulmonary vascular resistance of the native lung.(ABSTRACT TRUNCATED AT 250 WORDS)