Withdrawal forces of lumbar spinal catheters: no dependence on body position.

BACKGROUND: Spinal catheters, because of their smaller diameter, have lower tensile strength than epidural catheters. This study was designed to measure the withdrawal forces needed to remove lumbar spinal catheters and to determine whether patient position affects withdrawal forces. METHODS: Eighty-two patients with a 24-gauge spinal catheter placed midline at the lumbar L3/4 or L4/5 level were randomly assigned to catheter removal either in flexed lateral or sitting position. Withdrawal forces were measured using a tension spring balance. RESULTS: Mean withdrawal force was 0.91 N (95% CI: 0.73, 1.09) with extremes up to 5 N. Withdrawal force in the flexed lateral position was 1.04 N (95% CI: 0.73, 1.34) or in the sitting position was 0.78 N (95% CI: 0.59, 0.97). The 95% CI for the difference of the means was -0.62 N, 0.10 N. Thus, the absolute mean difference between the positions can be assumed to be smaller than 0.62 N. Neither the length of the spinal catheter under the skin or in the subarachnoid space, nor BMI influenced withdrawal force. CONCLUSION: Withdrawal force of spinal catheters is not influenced by body position during catheter removal, length of catheter under skin, or BMI.

In vitro effects of gelatin solutions on platelet function: a comparison with hydroxyethyl starch solutions.

The aim of this study was to investigate the effects of various gelatin and hydroxyethyl starch solutions on platelet reactivity. Citrated whole blood was obtained from 20 healthy volunteers. Expression of glycoprotein (GP) IIb-IIIa and p-selectin were determined using whole blood flow cytometry on both resting and agonist-activated platelets before and after in vitro haemodilution (20% and 40%) using oxypolygelatin, modified gelatin, urea-linked gelatin, hydroxyethyl starch (HES) 130 (mean molecular weight in kDa), HES 200, HES 450 and HES 550. High degrees of haemodilution using oxypolygelatin had no significant effect, similar to HES 130, whereas modified gelatin inhibited GP IIb-IIIa expression, similar to HES 200 and HES 450. Urea-linked gelatin significantly increased the expression of GP IIb-IIIa, similar to HES 550. p-selectin expression remained unchanged in all samples. The present in vitro study indicates that chemical characteristics of colloidal solutions modulate their influence on platelet reactivity.

Effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing non-ophthalmic surgery.

BACKGROUND AND OBJECTIVE: To compare the effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing elective non-ophthalmic surgery. METHODS: Thirty-two patients (ASA I-II) were randomized into two groups to receive either a continuous infusion of remifentanil (0.25-0.5 microg kg(-1) min(-1), n =16, Group R) or an intermittent bolus of fentanyl (2-5 microg kg(-1), n = 16, Group F) during the maintenance of anaesthesia. For the induction of anaesthesia, Group R received remifentanil 1 microg kg(-1) and Group F received fentanyl 2 microg kg(-1); both groups then received propofol 2 mg kg(-1) with vecuronium 0.1 mg kg(-1). Anaesthesia in both groups was maintained with a continuous infusion of propofol 4-8 mg kg(-1) h(-1). Ventilation of the lungs was controlled to a constant end-tidal PCO2 of 4.7-5.4 kPa. Blood pressure, electrocardiography, heart rate and oxygen saturation were monitored throughout anaesthesia. Intraocular pressure was determined before surgery, during the maintenance of anaesthesia, 2 min after emergence and in the recovery room using a Perkins hand-held applanation tonometer by an ophthalmologist blinded to the anaesthetic technique. RESULTS: After induction of anaesthesia, a significant decrease in intraocular pressure in the remifentanil group from 13.6 +/- 2.6 to 7.1 +/- 3.1 mmHg (P < 0.001) and in the fentanyl group from 13.7 +/- 2.2 to 9.7 +/- 3.4 mmHg (P < 0.001) was observed and maintained during anaesthesia. Thirty minutes after the end of anaesthesia, intraocular pressure returned to baseline values in both groups (remifentanil: 13.9 +/- 2.8 mmHg, P = 0.28; fentanyl: 13.6 +/- 2.3 mmHg, P = 0.59). The intraocular pressure and haemodynamic variables did not differ significantly between the two groups (intraocular pressure, P = 0.7327; blood pressure, P = 0.1295; heart rate, P = 0.8601). CONCLUSIONS: Remifentanil maintains intraocular pressure at an equally reduced level compared with fentanyl.

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.

Sevoflurane and propofol decrease intraocular pressure equally during non-ophthalmic surgery and recovery.

BACKGROUND: To provide good control of intraocular pressure (IOP) during anaesthesia and surgery, we conducted a study comparing the effects on IOP during maintenance and recovery of sevoflurane vs propofol anaesthesia in 33 patients (ASA I-II) undergoing elective non- ophthalmic surgery. METHODS: Anaesthesia was induced with propofol 2 mg kg(-1), fentanyl 2 micro g kg(-1) and vecuronium 0.1 mg kg(-1). Patients were allocated randomly to receive either propofol 4-8 mg kg(-1) h(-1) (group P; n=16) or 1.5-2.5 vol% sevoflurane (group S; n=17) for maintenance of anaesthesia. Fentanyl 2-4 micro g kg(-1) was added if necessary. The lungs were ventilated with 50% air in oxygen. Blood pressure, heart rate, oxygen saturation and end-tidal carbon dioxide were measured before and throughout anaesthesia and in the recovery room. IOP was determined with applanation tonometry (Perkins) by one ophthalmologist blinded to the anaesthetic technique. RESULTS: There was a significant decrease in IOP after induction and during maintenance of anaesthesia in both groups. No significant differences in IOP between the two groups was found. CONCLUSION: Sevoflurane maintains the IOP at an equally reduced level compared with propofol.

Quality of life in patients after meningioma resection.

OBJECTIVES: To evaluate quality of life in patients after tumour resection, to assess different dimensions of quality of life, to compare a newly designed questionnaire with the Nottingham Health Profile. SUBJECTIVE: A non-selected neurosurgically treated series of patients with meningiomas was investigated with reference to quality of life as a judgement of one's own needs and concerns and subjective disease dependent perception. METHODS: A postal survey was sent out to 155 patients who underwent resection of a meningioma between 1977 and 1993 at our clinic. The survey consisted of the specifically designed "Innsbruck Health Dimensions Questionnaire for Neurosurgical Patients" IHD(NS) and the Nottingham Health Profile NHP. The data were put into categories and analysed statistically (Chi-square, Mann Whitney U, Kruaskal-Wallis H-tests). RESULTS: 82 patients (53 female, 29 male) responded (response rate 59%). 10 had died and 7 had moved. The majority of patients (50/61% on NHP and 49/59.7% on IHD) had mild to moderate impairment of quality of life. 20% of the patients showed moderate to severe impairment of the dimensions: physical handicap and energy level. Physical impairment correlated to tumour size. This group was characterised by mainly belonging to the over 70ies age group and taking anti-epileptics. CONCLUSIONS: The quality of life impairments in most patients after tumour resection can be classified as mild to moderate. However, other disease and age effects are difficult to distinguish without a control group. The IHD(NS) correlated well with the NHP questionnaire.

The long-term antinociceptive effect of intrathecal S(+)-ketamine in a patient with established morphine tolerance.

IMPLICATIONS: Our report describes for the first time the continuous long-term intrathecal application of S(+)-ketamine in a patient with chronic pain and morphine tolerance. Intrathecally applied S(+)-ketamine led to a significant pain reduction and consecutively reduced the doses of intrathecal morphine required for pain relief even several weeks after the cessation of the 24-day period of intrathecal S(+)-ketamine administration.

Angiotropic large B-cell lymphoma misdiagnosed as urosepsis with multiple organ dysfunction syndrome.

A 53-year-old woman with a history of cervical carcinoma 14 years ago, treated with hysterectomy and radiation therapy, was admitted to the intensive care unit with severe SIRS (systemic inflammatory response syndrome) progressing to shock, multiple organ failure and death within 5 d. Bilateral hydronephrosis diagnosed by sonography and an enlarged left kidney with suspected abscesses verified in a CT-scan suggested the diagnosis of urosepsis. However, multiple microbiological examinations remained sterile. Despite surgical treatment and aggressive intensive care, she died in unresponsive shock. Pathohistologically, an angiotropic large B-cell lymphoma, a rare diffuse intravascular neoplasm of lymphoid origin, was diagnosed. The patient's history of abdominal radiation therapy 14 years earlier as well as multiple negative microbiological specimens in a patient with suspected urosepsis should have initiated the search for a non-infectious cause of the disease.

Dopamine and intestinal mucosal tissue oxygenation in a porcine model of haemorrhage.

Haemorrhage is associated with intestinal mucosal hypoxia and impaired gut barrier function. Dopamine increases oxygen delivery to the intestinal mucosa and may thus counteract haemorrhage-induced mucosal hypoxia. Jejunal mucosal tissue oxygen tension (mucosal PO2) and jejunal oxygen saturation of mucosal microvascular haemoglobin (mucosal HbO2) were measured in 14 anaesthetized pigs. Seven animals served as controls (group C) and seven received continuous infusion of dopamine 16 micrograms kg-1 min-1 (group D) while 45% of blood volume was removed in three equal increments. Resuscitation was performed using shed blood and fluid. Mean arterial pressure and systemic oxygen delivery decreasing significantly during haemorrhage and returned to baseline after resuscitation in both groups. Mucosal PO2 decreased from 4.4 to 1.7 kPa after haemorrhage (P < 0.01) and further to 1.5 kPa after resuscitation (P < 0.01) in group C whereas group D showed an increase from 3.9 to 5.9 kPa after the start of the dopamine infusion (P < 0.05), but no significant difference from baseline after haemorrhage (2.3 kPa) (ns) or resuscitation (3.1 kPa) (ns). Mucosal HbO2 decreased from 52 to 32% after haemorrhage (P < 0.05) and increased to near baseline (37%) (ns) after resuscitation in group C whereas group D showed no significant changes from baseline (54%) throughout the experiment. Comparison between groups showed higher mucosal PO2 and HbO2 values for group D animals after the start of the dopamine infusion (P < 0.05 each), after the first two steps of haemorrhage (P < 0.01 each) and after resuscitation (P < 0.05 each). We conclude that i.v. dopamine 16 micrograms kg-1 min-1 improved tissue oxygenation of the small intestinal mucosa during moderate haemorrhage and subsequent resuscitation.

Inotropic treatment and intestinal mucosal tissue oxygenation in a model of porcine endotoxemia.

OBJECTIVE: To evaluate the dose-related effects of dopamine, dopexamine, and dobutamine on intestinal mucosal tissue oxygenation following short-time infusion of Escherichia coli lipopolysaccharide, which has previously been shown to decrease mucosal tissue oxygenation by 60% of control values. DESIGN: Prospective, randomized, unblinded study. SETTING: Animal research laboratory. SUBJECTS: Anesthetized, mechanically ventilated domestic pigs. INTERVENTIONS: Pigs were infused with 2 microg/kg of E. coli lipopolysaccharide over 20 mins via the superior mesenteric artery. Pulmonary artery occlusion pressure was maintained near 15 mm Hg, using a mixed infusion regimen of Ringer's lactate solution and hydroxyethyl starch. Following endotoxemia, a small segment of the jejunal mucosa was exposed by midline laparotomy and antimesenteric incision. The control group (n = 7) received no further interventions. Pigs in the dopamine (n = 7), dopexamine (n = 7), and dobutamine (n = 7) groups were infused with 2.5, 5, 10, and 20 microg/kg/min of the respective drug via a central venous catheter. MEASUREMENTS AND MAIN RESULTS: Systemic hemodynamics as well as systemic, mesenteric, and femoral blood gas variables were measured using an arterial, a thermodilution pulmonary artery, a superior mesenteric venous, and a femoral venous catheter. Jejunal mucosal tissue PO2 was measured by means of two Clark-type surface oxygen electrodes. Oxygen saturation of jejunal mucosal microvascular hemoglobin was determined by tissue reflectance spectrophotometry. Infusion of endotoxin resulted in pulmonary hypertension. Systemic hemodynamics remained unchanged except for brief decreases in cardiac output and arterial blood pressure. Dopamine, dopexamine, and dobutamine increased systemic oxygen delivery in a dose-related manner by 80% (p < .01), 96% (p = .00), and 129% (p = .00) of values before inotropic treatment. Dopamine increased mucosal tissue PO2 by 109% (10-microg dose, p < .01) and 164% (20-microg dose, p = .00), and mucosal hemoglobin oxygen saturation by 61% (5-microg dose, p < .05), 102% (10-microg dose, p < 01) and 121% (20-microg dose, p = .00). Dopexamine increased mucosal tissue PO2 by 89% (20-microg dose, p < .01) and mucosal hemoglobin oxygen saturation by 26% (2.5-microg dose, p < .05) and 35% (5-, 10-, and 20-microg dose, p < .05). In the dobutamine and control groups, no significant effect on either mucosal tissue PO2 or hemoglobin oxygen saturation was observed. CONCLUSIONS: In this model of porcine endotoxemia, dopamine and, to a lesser extent, dopexamine increase intestinal mucosal tissue oxygenation. Of all three inotropes used, dobutamine has the most pronounced effect on systemic oxygen delivery, but it does not improve mucosal tissue oxygenation. Selective vasodilation within the intestinal mucosa, mediated mainly by dopamine-1 receptors, seems to explain the observed intestinal mucosal effect of dopamine and dopexamine.

The effects of progressive anemia on jejunal mucosal and serosal tissue oxygenation in pigs.

Anemia may promote intestinal hypoxia. We studied the effects of progressive isovolemic hemodilution on jejunal mucosal (Po2muc), and serosal tissue oxygen tension (Po2ser, Clark-type surface electrodes), mucosal microvascular hemoglobin oxygen saturation (Hbo2muc), and hematocrit (Hctmuc; tissue reflectance spectophotometry) in a jejunal segment. Twelve domestic pigs were anesthetized, paralyzed, and mechanically ventilated. Laparatomy was performed, arterial supply of a jejunal segment isolated, and constant pressure pump perfused. Seven animals were progressively hemodiluted to systemic hematocrits (Hctsys) of 20%, 15%, 10%, and 6%. Baseline for Po2muc, Po2ser and Hbo2muc was 23.5 +/- 2.1 mm Hg, 57.5 +/- 4 mm Hg, and 47.0% +/- 6.4% which were not different from the five controls. Despite a significant increase in jejunal blood flow, jejunal oxygen delivery decreased and oxygen extraction ratio increased significantly at Hctsys 10% and 6%. Po2ser decreased significantly below or at Hctsys of 15%, whereas Po2muc and Hbo2muc were maintained to Hctsys of 10%, but less than 10% Hbo2muc and mesenteric venous pH decreased significantly, implying that physiological limits of jejunal microvascular adaptation to severe anemia were reached. Decrease of Hctmuc was less pronounced than Hctsys. In conclusion, redistribution of jejunal blood flow and an increase in the ratio of mucosal to systemic hematocrit are the main mechanisms maintaining mucosal oxygen supply during progressive anemia.

Influence of anaesthesia and muscle relaxation on intubating conditions and sympathoadrenal response to tracheal intubation.

BACKGROUND: The study aimed to assess the relative influence of anaesthesia and muscle relaxation on intubating conditions and the haemodynamic and catecholamine responses to tracheal intubation. METHODS: Sixty ASA 1 or 2 patients were randomly assigned to one of four groups (15 patients each) that differed in the depth of anaesthesia (thiopentone plus fentanyl 2.5 microg x kg(-1) or thiopentone alone) and the degree of vecuronium-induced neuromuscular block (100% or > or =65%) at intubation. Muscle relaxation was measured at 0.1 Hz by means of mechanomyography. Heart rate (HR) and mean arterial blood pressure (MAP) were measured before and after induction of anaesthesia, and 1 min and 5 min following intubation, while adrenaline (A) and noradrenaline concentrations (NA) were determined from arterial blood samples. RESULTS: Intubating conditions were improved primarily by providing complete muscle relaxation at the adductor pollicis muscle (P<0.001) and to a lesser extent by adding fentanyl to thiopentone (P=0.04). The response of HR and MAP to tracheal intubation was attenuated mainly by fentanyl (P<0.001). Complete muscle relaxation further diminished the response of MAP to intubation (P=0.03). Changes in A and NA were dependent on the depth of anaesthesia only (P < or =0.01). CONCLUSION: The results of the study demonstrate that the sympathoadrenal response to intubation is attenuated by adding fentanyl (2.5 X kg[-1]) to an induction regimen with thiopentone, whereas provision of complete muscle relaxation at the adductor pollicis muscle is necessary to attain smooth intubating conditions.

[Patient knowledge concerning anesthesia general practice and the responsibilities of the anesthetist]. / Patientenwissen über die Praxis der Anästhesie und die Aufgaben des Anästhesisten.

In two Austrian university hospitals 104 patients were interviewed on the basis of questionnaires about their knowledge of the role of anaesthetists. Although 93% of the Patients considered anaesthesists to be physicians, major deficits were found regarding the knowledge about the spheres of activities of anaesthetists. 60% of the respondents confined the anaesthetist to the operating theatre. Only 55% considered the anaesthetist responsible for their safe recovery from anaesthesia. Previous anaesthesia showed to have no influence on the knowledge of anaesthesia practice and the role of anaesthetists. To current practice of informing the patient calls for improvement and new approaches. In addition to this further evaluation work on the influence of the mass media and public knowledge about anaesthesia and the anaesthetists' role should be undertaken.

Toxic shock syndrome in transsphenoidal neurosurgery.

An overlooked toxic shock syndrome (TSS) may lead to a fatal outcome. In neurosurgery a transsphenoidal approach with post-operative nasal tamponade may promote toxic shock syndrome without signs of local wound infection. By discussing the case history of a patient after hypophysectomy by the transsphenoidal route, we propose that after the appearance of the first signs of toxic shock syndrome, quick removal of the nasal tamponade is a life saving procedure.

Early bacterial infections in lung transplant recipients.

Early bacterial pulmonary infections within 2 weeks after lung transplantation were studied in 29 patients undergoing surgery between December 1989 and May 1992. Suspected pulmonary infections occurred in 11 patients (38 percent). The most common bacterial organisms isolated were Klebsiella pneumoniae (45 percent; 5/11), Pseudomonas aeruginosa (36 percent; 4/11), Escherichia coli (27 percent; 3/11), Staphylococcus aureus (18 percent; 2/11), and Enterobacter cloacae (18 percent; 2/11). The mortality due to infection was 3 percent (1/29) in the early postoperative period. None of the following variables was found to be of prognostic significance: positive donor cultures, ischemic time of the graft, use of cardiopulmonary bypass, number of courses of methylprednisolone for acute rejection, duration of postoperative intubation, and type of surgical procedure. The presence of infection in the early postoperative period did not influence long-term survival. In the absence of prognostic parameters, prompt adjustment of antibiotic therapy to the results of antibiograms remains the most important therapeutic step in the management of infections in the early postoperative period after lung transplantation.