Perioperative administration of fibrinogen does not increase adverse cardiac and thromboembolic events after cardiac surgery.

BACKGROUND: Although infusion of fibrinogen concentrate is increasingly used in bleeding patients after cardiac surgery, safety data are scarce. We aimed to evaluate the effect of perioperative administration of fibrinogen concentrate on postoperative morbidity and mortality in patients undergoing cardiac surgery. METHODS: During a 2 yr study period, 991 patients underwent cardiac surgery at a single university centre and were eligible for propensity score (PS) matching. We matched 190 patients with perioperative infusion of fibrinogen concentrate (median dose 2 g) with 190 controls without fibrinogen administration. After PS matching, crude outcome was analysed. Further, a multivariate logistic regression including additional risk factors for adverse outcome was performed. The primary endpoint was a composite of mortality and the occurrence of major cardiac and thromboembolic events within 1 yr. Secondary outcomes included mortality after 30 days and 1 yr and the composite of mortality and adverse events after 30 days. RESULTS: The administration of fibrinogen concentrate was not associated with an increased risk for mortality and thromboembolic or cardiac events within 1 yr after cardiac surgery [unadjusted hazard ratio (HR) 0.91; 95% confidence interval (CI) 0.55-1.49; P=0.697]. When using multivariate logistic regression model, the HR for adverse outcome in patients with administration of fibrinogen concentrate was 0.57 (95% CI 0.25-1.17; P=0.101). Similarly, the administration of fibrinogen concentrate did not adversely affect the secondary outcomes when applying unadjusted and multivariate regression analyses. CONCLUSIONS: Our study strongly suggests that the administration of fibrinogen concentrates at low dose is not associated with thromboembolic complications or adverse outcomes after cardiac surgery.

Bupivacaine concentrations in lumbar cerebrospinal fluid in patients with failed spinal anaesthesia.

BACKGROUND: Spinal anaesthesia (SA) has high success rates. However, inadequate block after SA has been reported even in the absence of technical problems. Various mechanisms for failed SA (FSA) have been proposed, but reports of cerebrospinal fluid (CSF) concentrations of local anaesthetics (LA) after FSA are scarce. We report lumbar CSF concentrations of bupivacaine in 20 patients in whom adequate block after subarachnoid injection failed to develop. METHODS: All patients with inadequate block after subarachnoid injection of plain bupivacaine 0.5% and in whom a second subarachnoid injection of LA was to be performed as a rescue technique were eligible for entry into this study. A CSF sample was withdrawn immediately before injection of the second dose of LA. Patients in whom failure was obviously due to technical problems or inadequate dosage were excluded. Bupivacaine concentrations were assessed with high-performance liquid chromatography. RESULTS: During the study period of 15 months, 2600 spinal anaesthetics were performed. The failure rate was 2.7% (71 patients). In 20 patients (0.77%), CSF concentrations of bupivacaine were determined, which ranged from 3.36 to 1020 microg ml(-1). CONCLUSIONS: Inadequate CSF concentration of LA is a common reason for FSA. However, in 12 of our 20 patients, concentrations were above 73 microg ml(-1), a concentration that should lead to an adequate block. In these patients, maldistribution of bupivacaine could be responsible for FSA. In view of the absence of sufficient block, despite adequate lumbar CSF concentrations of bupivacaine, concerns about neurotoxicity with repeat injections may be warranted.

Gastric intramucosal pH-guided therapy in patients after elective repair of infrarenal abdominal aneurysms: is it beneficial?

OBJECTIVE: To determine if gastric intramucosal pH (pHi)-guided therapy reduces the number of complications and length of stay in the intensive care unit (ICU) or the hospital after elective repair of infrarenal abdominal aortic aneurysms. DESIGN: Prospective, randomized study. SETTING: Surgical intensive care unit (SICU) of a University Hospital. PATIENTS: Fifty-five consecutive patients randomized to group 1 (pHi-guided therapy) or to group 2 (control). INTERVENTIONS: Patients of group 1 with a pHi of lower than 7.32 were treated by means of a prospective protocol in order to increase their pHi to 7.32 or more. MEASUREMENTS AND RESULTS: pHi was determined in both groups on admission to the SICU and thereafter at 6-h intervals. In group 2, the treating physicians were blinded for the pHi values. Complications, APACHE II scores, duration of endotracheal intubation, fluid and vasoactive drug treatment, treatment with vasoactive drugs, length of stay in the SICU and in the hospital and hospital mortality were recorded. There were no differences between groups in terms of the incidence of complications. We found no differences in APACHE II scores on admission, the duration of intubation, SICU or hospital stay, or hospital mortality. In the two groups the incidence of pHi values lower than 7.32 on admission to the SICU was comparable (41% and 42% in groups 1 and 2, respectively). Patients with pHi lower than 7.32 had more major complications during SICU stay (p < 0.05), and periods more than 10 h of persistently low pHi values (< 7.32) were associated with a higher incidence of SICU complications (p < 0.01). CONCLUSIONS: Low pHi values (< 7.32) and their persistence are predictors of major complications. Treatment to elevate low pHi values does not improve postoperative outcome. Based on these data, we cannot recommend the routine use of gastric tonometers for pHi-guided therapy in these patients. Further studies are warranted to determine adequate treatment of low pHi values that results in beneficial effects on the patient's postoperative course and outcome.

Mechanism of antinociceptive action of clonidine in nonmyelinated nerve fibres.

Despite a large body of clinical evidence in favour of a local anesthetic effect of clonidine, the underlying mechanism has not yet been elucidated. In this study we have used the sucrose-gap method to measure the effects of clonidine on the electrophysiological properties of nonmyelinated nerve fibers in the rabbit vagus nerve. The results showed that clonidine enhanced the hyperpolarizing and reduced the depolarizing afterpotential that follow compound action potentials during electrical activity. We showed that summation of these afterpotentials shifts the membrane potential toward more negative values, thus creating a region of low safety conduction, where the local circuit currents might fail to depolarize the axonal membrane to the threshold value needed to open voltage-dependent Na(+) channels. Yohimbine did not reverse the inhibitory effects of clonidine on impulse propagation, indicating that the observed effects of clonidine relies on mechanisms not mediated by alpha(2)-adrenoceptors.

[Normal values in rhinomanometry]. / Beitrag zu den Normwerten in der Rhinomanometrie.

Despite various methods of investigation, there are few reports as to the normal values of nasal airway resistance. A total of 56 adult subjects free of any nasal disease underwent nasal airway resistance measurement using active anterior rhinomanometry according to the guidelines of the international committee on standardization of rhinomanometry. Inspiratory and expiratory resistance was measured before and after application of a topical decongestant spray. This test was reproducible in that 46 of the subjects underwent a second study with resistance values quite close to that of the initial measurement. The upper range of the total inspiratory nasal airway resistance was 0.45 Pa s/cm3 before and 0.3 Pa s/cm3 after decongestant administration. There was no statistically significant difference between the inspiratory and expiratory resistance measurements. No correlation could be made between nasal airway resistance, age, sex, height or weight.

[Clinical comparison of 2 modern rhinomanometers]. / Klinischer Vergleich zweier moderner Rhinomanometer.

Two rhinomanometers (the NR 6 manufactured by Mercury, Scotland and the Rhino-Comp manufactured by Cintec, Sweden) were tested and compared in five subjects. Both instruments are suitable for clinical use and produced equal measurements of nasal airway resistance. The Rhino-Comp device is easier to handle. Technical improvements would be desirable in both machines.

Toxicity of spinal local anaesthetics.

Recent reports of severe neurological injury after spinal anaesthesia have generated concerns about the neurotoxic potential of local anaesthetics and, in particular, of lignocaine. Further, there is an increasing body of evidence indicating that transient neurological symptoms commonly occur after uneventful lignocaine spinal anaesthesia but not after bupivacaine. Results from an epidemiological study suggest that patient positioning and outpatient status are major co-factors. Neither the dose nor the concentration of lignocaine appear to reduce the risk for transient neurological symptoms. Available data on alternative short-acting local anaesthetics with respect to transient neurological symptoms are limited and conflicting. Experimental data provide further information on factors contributing to local anaesthetic induced neurotoxicity: adrenaline significantly increases the neurotoxic effects of lignocaine in vivo, whereas the addition of glucose does not.

Vasovagal heart block following cataract surgery under local anesthesia.

Hemodynamic alterations during eye surgery usually consist of sinus bradycardia and hypotension provoked by the oculocardiac reflex. We report a case in which severe sinus bradycardia occurring immediately after the end of surgery was complicated by second-degree atrioventricular block, hypotension, and symptomatic myocardial ischemia.

Spinal anaesthesia in a patient with Takayasu's disease.

We report the successful anaesthetic management of therapeutic abortion under spinal anaesthesia in a 32-yr-old woman with Takayasu's disease. The pathology and pathophysiology of this syndrome and their impact on anaesthesia are discussed.

Allergic contact dermatitis from ethyl chloride and sensitization to dichlorodifluoromethane (CFC 12).

Despite the widespread use of ethyl chloride as a local anesthetic and chlorofluorocarbons as propellants in medical and cosmetic aerosols, contact allergy to these 2 gases is rare. In a 30-year-old woman, an unusual itchy dermatitis appeared at all skin sites where a medical aerosol containing ethyl chloride had been briefly applied. Subsequent re-exposure to the spray and patch tests revealed contact sensitization to ethyl chloride and dichlorodifluoromethane (CFC 12). Histologic and immunohistochemical examinations of the test reaction were consistent with a T-cell-mediated allergic reaction. The low incidence of contact allergy to ethyl chloride and chlorofluorocarbons may be due to the rapid evaporation of these volatile gases, thus preventing intense and prolonged contact with the skin and consequently contact sensitization. A modified patch test procedure using perforated plastic chambers to allow gas evaporation is necessary to test volatile agents.

Transient neurologic symptoms after spinal anesthesia.

We recently reported several cases consistent with transient radicular irritation after spinal anesthesia with hyperbaric 5% lidocaine. The present prospective, blind, nonrandomized study was performed to determine the incidence of these transient neurologic symptoms and to identify factors that might be associated with their occurrence. We studied 270 patients scheduled for gynecologic or obstetric procedures under spinal anesthesia. For spinal anesthesia, either 5% lidocaine in 7.5% glucose or 0.5% bupivacaine in 8.5% glucose was used. Patients were evaluated on postoperative day 3 by a quality assurance nurse who was unaware of the drug given or details of the anesthetic technique. Transient neurologic symptoms were observed in 37% of patients receiving 5% lidocaine, whereas only one patient receiving 0.5% bupivacaine had transient hypesthesia of the lateral aspect of the right foot. These results suggest that symptoms were the result of a specific drug effect. However, because of the limitations of the study one cannot conclude that lidocaine per se was the cause.

Epinephrine increases the neurotoxic potential of intrathecally administered lidocaine in the rat.

BACKGROUND: Epinephrine is commonly added to lidocaine solutions to increase the duration of spinal anesthesia. Despite this common usage, the effect of epinephrine on the neurotoxic potential of this anesthetic is not known. The current experiments investigated whether adding epinephrine increases functional impairment or histologic damage induced by spinal administration of lidocaine in the rat. METHODS: Eighty rats were divided into four groups to receive an intrathecal injection of normal saline containing either 5% lidocaine, 5% lidocaine with 0.2 mg/ml of epinephrine, 0.2 mg/ml of epinephrine, or normal saline alone. Animals were assessed for persistent sensory impairment using the tail-flick test administered 4 and 7 days after infusion. Animals were then killed, and the spinal cord and nerve roots were prepared for neuropathologic evaluation. RESULTS: Rats given 5% lidocaine developed persistent sensory impairment and histologic damage, and the addition of epinephrine resulted in a further significant increase in injury. Sensory function in animals given epinephrine without anesthetic was similar to baseline and did not differ from saline. Histologic changes in animals treated with epinephrine alone did not differ significantly from saline controls. CONCLUSIONS: The neurotoxicity of intrathecally administered lidocaine is increased by the addition of epinephrine. When making clinical recommendations for maximum safe intrathecal dose of this anesthetic, one may need to consider whether the solution contains epinephrine.

Preoperative anxiolysis with minimal sedation in elderly patients: bromazepam or clorazepate-dipotassium?

BACKGROUND: In elderly patients undergoing ophthalmic surgery the loss of co-operation due to over-sedation, induced by drugs given preoperatively, may jeopardise the success of microsurgery performed under regional anaesthesia. The aim of this study was to compare the psychotropic effects of bromazepam and clorazepate-dipotassium, two benzodiazepines with predominantly anxiolytic and only weak sedative action. METHODS: A randomised, placebo-controlled, double-blind study was designed to include 60 patients, ASA physical status II-III, older than 60 years scheduled for ophthalmic surgery under regional anaesthesia. The patients were randomised to receive either bromazepam (3 mg) or clorazepate-dipotassium (20 mg) or placebo. The study drugs were given at 10 p.m. the night before surgery and 90 min before surgery. Using the State-Trait Anxiety Inventory (STAI), the patient's anxiety was assessed at the end of the preoperative visit, on the next morning before the study drug was given and on arrival at the operating theatre. RESULTS: Bromazepam induced a marked anxiolytic effect as documented by a significant reduction in the STAI State values after both applications (P<0.01). Clorazepate did not differ from placebo at any evaluation time with regard to the STAI and haemodynamic values. Sedative effects and oxygen saturation (SpO2) were comparable in all groups. CONCLUSION: Bromazepam is superior to clorazepate in its anxiolytic action and suitable as preoperative medication in the elderly patient because of lack of overt sedative effects.

Intravenous sedation for retrobulbar injection and eye surgery: diazepam and/or propofol?

Principle goals of sedation for eye surgery are to provide patient comfort and to allow the patient to stay calm during both retrobulbar injection and surgery. Insufficient sedation may not prevent the patient from moving during retrobulbar injection, whereas very deep sedation may result in respiratory complications during surgery. The aim of the present study was to evaluate the effectiveness and suitability of a combination of diazepam and propofol for sedation for both application of retrobulbar block and subsequent elective eye surgery. One-hundred and fifty patients were randomly allocated to receive either diazepam, propofol or a combination of both drugs before retrobulbar injection. Tolerance of retrobulbar injection and comfort during the surgical procedure were assessed by comfort scores using a nominal analogue scale between 1 (worst possible condition) and 6 (best conceivable condition). Side effects related to sedation were recorded. The combination of diazepam and propofol resulted in the highest comfort scores for both retrobulbar block (5.3 +/- 0.3) and the surgical procedure (5.4 +/- 0.4). Diazepam alone did not produce adequate sedation for retrobulbar block (3.1 +/- 0.3), whereas comfort scores during surgery were significantly higher (5.3 +/- 0.3) compared to propofol alone (3.6 +/- 0.4). No severe side effects induced by sedation were noted in any of the study groups. The combination of diazepam and propofol proved able to provide a reliable degree of sedation with minimal side effects for both retrobulbar block and surgery. The combination was clearly superior to the sedation induced by propofol or diazepam alone.

Transient radicular irritation after single subarachnoid injection of isobaric 2% lignocaine for spinal anaesthesia.

Several cases have been reported recently in which symptoms suggestive of transient radicular irritation occurred following the use of hyperbaric 5% lignocaine for spinal anaesthesia. We report on three patients in whom we observed similar symptoms attributable to this kind of radicular irritation following uneventful spinal anaesthesia using isobaric 2% lignocaine. All three patients underwent minor gynaecological procedures and developed burning pains in the buttocks within 24 h of surgery. The long-term outcome was not clear for all the patients, but in at least one the pain disappeared.

Perioperative administration of caffeine tablets for prevention of postoperative headaches.

Interruption of daily caffeine consumption can cause caffeine withdrawal headache. As headache ranks among the most frequent minor postoperative sequelae, the impact of perioperative substitution of caffeine on the incidence of postoperative headache was evaluated. Forty patients undergoing minor surgical procedures with general anaesthesia were randomly allocated to receive either placebo or caffeine tablets at a dosage equal to their individual average daily caffeine consumption. Daily dietary intake was calculated based on an average week-day consumption using conversion factor from previously published sources. The patients were instructed at the preoperative visit to abstain from all external sources of caffeine. Compliance with these dietary restrictions was verified by blood samples obtained immediately before the surgical procedure and on postoperative day 1. The patients were assessed for headache using a standardised checklist immediately before induction of anaesthesia, on the evening of the day of surgery and on the morning of postoperative day 1. Ten patients (50%) who received placebo reported headaches, which persisted in seven patients (35%) until the next day. No patient receiving caffeine substitution therapy reported headache following surgery, and only one complained of headache on postoperative day 1. We suggest that the prophylactic administration of caffeine tablets might be considered for surgical patients who are accustomed to a high daily intake of caffeine.

A similar incidence of transient neurologic symptoms after spinal anesthesia with 2% and 5% lidocaine.

Recent reports suggest that transient neurologic symptoms are common after spinal anesthesia with 5% lidocaine. To determine whether reducing the anesthetic concentration might decrease the incidence of symptoms, 50 ASA class I or II patients undergoing brief gynecologic procedures under spinal anesthesia were randomly allocated to receive 1 mg/kg of either 5% or 2% lidocaine in 7.5% glucose. Patients were evaluated on the first postoperative day by an anesthesiologist who was unaware of the solution administered or the details of the anesthetic procedure. Symptoms suggestive of transient radicular irritation were observed in 8 patients (32%) receiving 5% lidocaine, and in 10 patients (40%) receiving 2% lidocaine (NS). These results confirm our previous findings that transient neurologic symptoms may occur in up to one third of the patients receiving 5% lidocaine, and indicate that a modest reduction in lidocaine concentration does not reduce risk.

Teaching the use of fiberoptic intubation for children older than two years of age.

UNLABELLED: In 144 anesthetized children aged 2-9 yrs, the safety and feasibility of orotracheal fiberoptic intubation, with and without an airway endoscopy mask, were assessed and compared with laryngoscopic intubation. Eight anesthesia residents with experience in adult fiberoptic intubation, but who were beginners in pediatric anesthesia, participated in this study. In a randomized fashion, each resident intubated 18 children (6 in each group). The time (mean +/- SD) to achieve successful intubation was different for laryngoscopic and fiberoptic intubation (34 +/- 17 s and 80 +/- 39 s, respectively; P < 0.001). The use of the airway endoscopy mask further prolonged fiberoptic intubation (167 +/- 121 s, P < 0.001). Spo2 values remained >95% in all patients during conventional laryngoscopy and fiberoptic laryngoscopy with a mask, whereas Spo2 decreased below 95% in 2 of the 48 patients during fiberoptic intubation without a mask. Both patients promptly recovered during ventilation via a face mask. We conclude that teaching the use of fiberoptic intubation in healthy, anesthetized children aged 2-9 yrs is safe and feasible. IMPLICATIONS: Fiberoptic intubation is a valuable technique of airway management. We studied the feasibility and safety of a training program that could be used for children more than 2 yrs old. This study demonstrates that fiberoptic intubation can be effectively practiced in pediatric patients without increased risk of side effects.

[Perioperative gastrointestinal ischemia in abdominal aortic aneurysm operations]. / Perioperative gastrointestinale Ischämien bei abdominalen Aortenaneurysma-Operationen.

QUESTIONS UNDER STUDY: Surgery of abdominal aortic aneurysms involves a high risk of postoperative complications. It has been suggested that the incidence of postoperative complications is related to the development of gastrointestinal acidotic episodes of the mucosa. The goal of this study was, therefore, to determine the incidence of gastrointestinal acidotic episodes during repair of abdominal aortic aneurysms, and to test the hypothesis that these episodes predict an adverse postoperative course. METHODS: In 49 consecutive patients undergoing elective surgery for repair of an abdominal aneurysm, intramucosal gastric pH (pHi) was measured perioperatively. The length of the surgical procedure, perioperative intravenous fluid intake, use of vasoactive drugs, APACHE-II scores, days with an endotracheal tube in place, days of intensive care and major postoperative complications were prospectively assessed. The patients were assigned to either a group with a pHi > or = 7.35 or a group with pHi < 7.35 measured towards the end of the surgical procedure, and then compared. RESULTS: The pHi decreased from 7.42 +/- 0.09 after induction of anesthesia to 7.37 +/- 0.07 (p < 0.05) during clamping of the aorta, and continued to decrease to 7.34 +/- 0.08 (p < 0.001) towards the end of surgery and on admission to the surgical intensive care unit (mean +/- standard deviation). The percentage of patients with pHi < 7.35 increased from 10% at the beginning of the operation to 55% on admission to the intensive care unit (p < 0.0001). There was no difference in the postoperative course between patients with pHi > or = 7.35 and those with pHi < 7.35 measured after declamping of the aorta. Patients who had a major complication during their stay in the intensive care unit had lower perioperative pHi values than patients without complications (p < 0.001). CONCLUSIONS: Perioperative gastrointestinal acidotic episodes of the mucosa are common during repair of abdominal aortic aneurysms. The perioperative course, however, is not influenced by these acidotic episodes, despite the fact that patients with complications during their stay in the intensive care unit had lower perioperative pHi values. The routine use of pHi measurements during elective surgery of abdominal aortic aneurysms, therefore, is not justified.