Practice patterns in choice of left double-lumen tube size for thoracic surgery

BACKGROUND

Some anesthesiologists choose smaller than body size-appropriate left sided double-lumen tubes (DLTs) ("down-size") for lung isolation in an attempt to limit the risk of airway trauma. There are few data on the effects of DLT size on intraoperative outcome measures.

METHODS

In 300 adults undergoing thoracic surgery requiring lung isolation, we conducted a prospective pilot study to evaluate whether the use of 35 FR DLT, regardless of gender and/or height (care standard of two investigators), was associated with a similar incidence of intraoperative hypoxemia, lung isolation failure, or need for DLT repositioning during surgery (noninferiority) than with the conventional goal of inserting the largest possible DLT (care standard of two other investigators). DLT insertion position was immediately confirmed with fiberoptic bronchoscopy after direct laryngoscopic placement and after lateral positioning.

RESULTS

The combined incidence of transient hypoxemia, inadequate lung isolation, or need for DLT repositioning during surgery did not differ among patients receiving 35, 37, or 39 FR DLT, regardless of gender or height. Despite the high frequency of 35 FR DLT use, 2% of patients required further down-sizing due to the inability to introduce the DLT into the left mainstem bronchus or when no inflation of the bronchial cuff was needed for lung isolation.

CONCLUSIONS

Under the conditions of this pilot study, the use of smaller than conventionally sized DLT was not associated with any differences in clinical intraoperative outcomes.

Toe necrosis and acute myocardial infarction precipitated by a pheochromocytoma in a patient with systemic sclerosis

Systemic sclerosis (SSc) patients typically experience Raynaud phenomena that is often complicated by digital ischemic lesions, gangrene, and digital loss. Other causes of peripheral ischemia, such as atherosclerosis, cryoglobulinemia, antiphospholipid syndrome, myeloproliferative disorders, paraneoplastic syndromes, and hyperadrenergic endocrine conditions, may be masked in SSc patients. We present a woman with limited SSc who developed toe necrosis and acute coronary events as a complication of a previously undiagnosed pheochromocytoma.

The safety zone of percutaneous cervical approach: a dynamic computed tomographic study

STUDY DESIGN

A prospective study using computed tomography (CT) scans.

OBJECTIVE

To identify the structures at risk and the safety zone of a percutaneous cervical approach.

SUMMARY OF BACKGROUND DATA

A percutaneous cervical approach may injure the important structures of the anterior neck. However, the dynamic locations of vital structures and the structures at risk by routine trajectory have not been analyzed.

METHODS

Thirty patients were enrolled for this study. We obtained the CT scans of the cervical spine at each level of the intervertebral disc from C3-C4 to C6-C7, after manually pushing the airway in the same position and manner of discography. The patients ingested contrast materials for imaging of their digestive tracts and were injected intravenous contrast materials for imaging of vascular structures, just before obtaining images. We estimated the distances from the operator's fingertip to the digestive tract on the left side and to the carotid artery on the right side, at each level. The safety zone was determined by the sum of 2 distance calculations. We identified the anatomic structure at risk by simulated needle insertion toward the center of the disc through the safety zone.

RESULTS

At C3-C4, the safety zone was measured 18.9 +/- 6.6 mm. The superior thyroidal artery (STA) was located in the safety zone of C3-C4 in 86.7%. At C4-C5, the safety zone was measured 23.5 +/- 6.5 mm. The STA and the right lobe of the thyroid gland (TG) were located in the safety zone in 26.7% and 30%, respectively. At C5-C6, the safety zone was measured 33.7 +/- 6 mm. The TG was located in the safety zone of C5-C6 in 76.7%. At C6-C7, the safety zone was 29.2 +/- 4.5 mm. The TG was located on the approach plane in 90%.

CONCLUSION

The safety zone was wider at the distal level (C5-C6, C6-C7) than at the proximal level (C3-C4, C4-C5). The safest needle entry point should be between the pushing point of the airway and the pulsating point of the carotid artery. In addition, the needle should be approached toward the center of the disc. A percutaneous cervical approach allows a low risk of pharyngoesophageal structure injury and is considered a safe diagnostic technique in dynamic imaging studies.

The change in zoster-associated pain treated with oral valaciclovir in immunocompetent patients with acute herpes zoster

We have analysed zoster-associated pain treated with valaciclovir (VCV) in immunocompetent patients with acute herpes zoster over 6 months, and evaluated the safety of VCV. We know of no reports that evaluate postherpetic neuralgia (PHN) treated with VCV for 6 months. Predisposing factors that influence PHN were age (over 60 years), clustered vesicles, severity of eruption, sleep disturbance, and hypesthesia. Timing of the administration of VCV before or after the onset of rash did not influence the incidence of PHN. No serious adverse reactions were observed during the administration of VCV.

Recurrent herpes simplex virus infection in a patient with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy associated with L29P and IVS9-1G>C compound heterozygous autoimmune regulator gene mutations

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) has characteristic clinical features with organ-specific autoimmune polyendocrine diseases and candidiasis, caused by the mutations of autoimmune regulator (AIRE) gene. Although almost all patients are complicated with mucocutaneous candidiasis, no apparent susceptibility to other infections has yet been reported. We herein report that a patient with APECED suffered from recurrent herpes simplex virus type 1 (HSV-1) infection after severe primary herpetic stomatitis, associated with sequential HSV-1 isolates of the same genomic profile, consistent with endogeneous recurrence. Thus, not only candidiasis but also HSV infection should receive more attention in patients with APECED, with treatment being administered accordingly.

Sympathetic nerve blocks in mandibular herpes zoster and postherpetic neuralgia

Sympathetic blocks have been indicated for the diagnosis and treatment of painful neuropathic conditions, such as herpes zoster (HZ) and postherpetic neuralgia (PHN). The purpose of this article is to report a case of mandibular HZ and PHN in an HIV-positive patient, and discuss the efficacy of sympathetic nerve blocks for pain relief and prevention of PHN.

Predicting postherpetic neuralgia in elderly primary care patients with herpes zoster: prospective prognostic study

Postherpetic neuralgia (PHN) is the most frequent complication of herpes zoster (HZ) and difficult to treat. Timely identification of high-risk HZ-patients enables physicians to focus on PHN prevention. To assess which simple to measure factors are independent predictors of PHN, and whether psychosocial and serological/virological parameters have additional predictive value, a prospective cohort study in primary care was conducted. We included 598 elderly (>50 years) consecutive patients with acute HZ (rash <7 days) below sixth cervical dermatome. At baseline demographic, clinical (e.g., duration and severity of pain and rash), psychological (Pain Cognition List [PCL] and Spielberger's Anxiety Inventory), serological (VZV-antibodies) and virological (viremia presence) variables were measured. Blood tests were performed in a random subset of 218 patients. Primary outcome was significant pain (VAS >30 on 0-100 scale) after three months. The final prediction model obtained from multivariable logistic regression was (internally) validated using bootstrapping techniques, and adjusted for optimism. Forty-six (7.7%) patients developed PHN. Independent predictors were age (odds ratio [OR]=1.08 per year), acute pain severity (OR=1.02 per unit), presence of severe rash (OR=2.31), and rash duration before consultation (OR=0.78 per day): area under receiver-operating-characteristic curve [ROC area]=0.77 (95% CI: 0.71-0.82). Of the five PCL scores, only factor V ('trust in healthcare') was an additional predictor (OR=1.01 per unit), though it increased the ROC area with only 0.01 to 0.78. The Spielberger's anxiety scores and serological and virological variables were no additional predictors. Thus, four simple variables can help physicians to timely identify elderly HZ-patients at risk of PHN.

Which device should be considered the best for lung isolation: double-lumen endotracheal tube versus bronchial blockers

PURPOSE OF REVIEW

This review is a clinical comparison between double-lumen endotracheal tubes and bronchial blockers to determine which device is considered the best for lung isolation.

RECENT FINDINGS

Double-lumen endotracheal tubes and bronchial blockers have been found to be clinically equivalent in terms of performance in providing lung collapse for patients with normal airways. In the last five years, however, numerous reports have indicated a preference for the use of bronchial blockers in patients with airway abnormalities. For nonthoracic anesthesiologists who have limited experience in thoracic anesthesia cases, none of the devices (double-lumen tubes or bronchial blockers) have been shown to provide any advantage while in use due to a high incidence of unrecognized malpositions. Overall, each device provides advantages depending upon the case, such as absolute lung separation with a double-lumen endotracheal tube or the use of a bronchial blocker in a difficult airway for a patient requiring lung isolation.

SUMMARY

Double-lumen endotracheal tubes and bronchial blockers should be part of the armamentarium of every anesthesiologist involved in lung isolation techniques and every device should be tailored to specific case needs.

Recommendations for the management of herpes zoster

The objective of this article is to provide evidence-based recommendations for the management of patients with herpes zoster (HZ) that take into account clinical efficacy, adverse effects, impact on quality of life, and costs of treatment. Systematic literature reviews, published randomized clinical trials, existing guidelines, and the authors' clinical and research experience relevant to the management of patients with HZ were reviewed at a consensus meeting. The results of controlled trials and the clinical experience of the authors support the use of acyclovir, brivudin (where available), famciclovir, and valacyclovir as first-line antiviral therapy for the treatment of patients with HZ. Specific recommendations for the use of these medications are provided. In addition, suggestions are made for treatments that, when used in combination with antiviral therapy, may further reduce pain and other complications of HZ.

Anesthesia for cesarean section in a patient with Holt-Oram syndrome

Holt-Oram syndrome is a rare genetic disorder affecting the heart and upper limbs (atriodigital dysplasia). The manifestations of the limb defects may vary in severity from subtle carpal bone defects and triphalangeal thumb to digit aplasia and upper extremity phocomelia. Cardiac abnormalities include atrial and/or ventricular septal defects, anomalies in pulmonary venous return and various dysrhythmias. We present the anesthetic management of a parturient with this syndrome who underwent elective cesarean section and tubal ligation, conducted under combined spinal-epidural anesthesia with a low dose of intrathecal bupivacaine. Our goal was to avoid an excessively high sympathetic block or excessive sympathetic stimulation accompanied by potential deleterious effects on cardiac rhythm. Cardiac monitoring was continued in the postoperative period for 6 h because of the possibility of dysrhythmia.

Use of the Esophageal Doppler Machine to help guide the intraoperative management of two children with pheochromocytoma

The anesthetic management of pheochromocytoma has been based upon the intraoperative control of blood pressure and fluid balance following adequate preoperative preparation. This can be difficult, especially in the presence of significant comorbidity such as cardiac or renal dysfunction. Two cases of children with pheochromocytoma are reported where the introperative management of fluid balance and blood pressure control were guided by measurement of changes in descending aortic blood flow using an esophageal Doppler probe. The advantages of such a technique compared with more invasive monitors are discussed.

Developments in herpes simplex virus vaccines: old problems and new challenges

Vaccination has remained the best method for preventing virus spread. The herpes simplex virus (HSV) candidate vaccines tested till now were mostly purified subunit vaccines and/or recombinant envelope glycoproteins (such as gB and gD). In many experiments performed in mice, guinea pigs and rabbits, clear-cut protection against acute virus challenge was demonstrated along with the reduction of the extent of latency, when established in the immunized host. The immunotherapeutic effect of herpes vaccines seems less convincing. However, introduction of new adjuvants, which shift the cytokine production of helper T-cells toward stimulation of cytotoxic T-cells (TH1 type cytokine response), reveals a promising development. Mathematical analysis proved that overall prophylactic vaccination of seronegative women, even when eliciting 40-60 % antibody response only, would reduce the frequency of genital herpes within the vaccinated population. Even when partially effective, immunotherapeutic vaccination might represent a suitable alternative of chronic chemotherapy in recurrent labial and genital herpes.

Epidural anesthesia and pulmonary function

The epidural administration of local anesthetics can provide anesthesia without the need for respiratory support or mechanical ventilation. Nevertheless, because of the additional effects of epidural anesthesia on motor function and sympathetic innervation, epidural anesthesia does affect lung function. These effects, i.e., a reduction in vital capacity (VC) and forced expiratory volume in 1 s (FEV(1.0)), are negligible under lumbar and low thoracic epidural anesthesia. Going higher up the vertebral column, these effects can increase up to 20% or 30% of baseline. However, compared with postoperative lung function following abdominal or thoracic surgery without epidural anesthesia, these effects are so small that the beneficial effects still lead to an improvement in postoperative lung function. These results can be explained by an improvement in pain therapy and diaphragmatic function, and by early extubation. In chronic obstructive pulmonary disease (COPD) patients, the use of thoracic epidural anesthesia has raised concerns about respiratory insufficiency due to motor blockade, and the risk of bronchial constriction due to sympathetic blockade. However, even in patients with severe asthma, thoracic epidural anesthesia leads to a decrease of about 10% in VC and FEV(1.0) and no increase in bronchial reactivity. Overall, epidural administration of local anesthetics not only provides excellent anesthesia and analgesia but also improves postoperative outcome and reduces postoperative pulmonary complications compared with anesthesia and analgesia without epidural anesthesia.

Development and Evaluation of a Generic Physiologically Based Pharmacokinetic Model for Children

BACKGROUND

Clinical trials in children are being encouraged by regulatory authorities in light of the immense off-label and unlicensed use of drugs in the paediatric population. The use of in silico techniques for pharmacokinetic prediction will aid in the development of paediatric clinical trials by guiding dosing regimens, ensuring efficient blood sampling times, maximising therapeutic effect and potentially reducing the number of children required for the study. The goal of this study was to extend an existing physiologically based pharmacokinetic (PBPK) model for adults to reflect the age-related physiological changes in children from birth to 18 years of age and, in conjunction with a previously developed age-specific clearance model, to evaluate the accuracy of the paediatric PBPK model to predict paediatric plasma profiles.

METHODS

The age-dependence of bodyweight, height, organ weights, blood flows, interstitial space and vascular space were taken from the literature. Physiological parameters that were used in the PBPK model were checked against literature values to ensure consistency. These included cardiac output, portal vein flow, extracellular water, total body water, lipid and protein. Five model compounds (paracetamol [acetaminophen], alfentanil, morphine, theophylline and levofloxacin) were then examined by gathering the plasma concentration-time profiles, volumes of distribution and elimination half-lives from different ages of children and adults. First, the adult data were used to ensure accurate prediction of pharmacokinetic profiles. The model was then scaled to the specific age of children in the study, including the scaling of clearance, and the generated plasma concentration profiles, volumes of distribution and elimination half-lives were compared with literature values.

RESULTS

Physiological scaling produced highly age-dependent cardiac output, portal vein flow, extracellular water, total body water, lipid and protein values that well represented literature data. The pharmacokinetic profiles in children for the five compounds were well predicted and the trends associated with age were evident. Thus, young neonates had plasma concentrations greater than the adults and older children had concentrations less than the adults. Eighty-three percent, 97% and 87% of the predicted plasma concentrations, volumes of distribution and elimination half-lives, respectively, were within 50% of the study reported values. There was no age-dependent bias for term neonates to 18 years of age when examining volumes of distribution and elimination half-lives.

CONCLUSION

This study suggests that the developed paediatric PBPK model can be used to scale pharmacokinetics from adults. The accurate prediction of pharmacokinetic parameters in children will aid in the development of dosing regimens and sampling times, thus increasing the efficiency of paediatric clinical trials.

Postherpetic Neuralgia: The Never-Ending Challenge

Postherpetic neuralgia (PHN) is defined as pain that persists 1 to 3 months following the rash of herpes zoster (HZ). PHN affects about 50% of patients over 60 years of age and 15% of all HZ patients. Patients with PHN may experience two types of pain: a steady, aching, boring pain and a paroxysmal lancinating pain, usually exacerbated by contact with the involved skin. Herpes zoster is initially a clinical diagnosis, based on the observation of a typical dermatomal distribution of rash and radicular pain. HZ is pathologically characterized by inflammatory necrosis of dorsal root ganglia, occasionally associated with evidence of neuritis, leptomeningitis, and segmental unilateral degeneration of related motor and sensory roots. Although acyclovir has been used successfully as standard therapy for varicella zoster virus (VZV) infection in the past decade, resistant strains of VZV are often recognized in immunocompromised patients. Therapy with acyclovir and the use of corticosteroids have been reported to prevent PHN in up to 60% of HZ patients. Management of chronic pain in PHN is more problematic. The only therapy proven effective for PHN in controlled study is the use of tricyclic antidepressants, including amitriptyline and desipramine. There is good evidence of efficacy from randomized trials that gabapentin and pregabalin (new anticonvulsant drugs) are of benefit in the reduction of pain from PHN. As alternative therapies, topical agents such as capsaicin, lidocaine or opioid analgesic treatment may give satisfactory results. Interventions with low risk, such as transcutaneous electrical nerve stimulation (TENS), are appropriate. Evidence is scant for the value of surgical and procedural interventions in general, although there are numerous, small studies supporting the use of specific interventions such as nerve blocks, neurosurgical procedures, and neuroaugmentation. Although antiviral agents are appropriate for acute HZ, and the use of neural blockade and sympathetic blockade may be helpful in reducing pain in selected patients with HZ, there is little evidence that these interventions will reduce the likelihood of developing PHN. Postherpetic neuralgia remains a difficult pain problem. This review describes the epidemiology and pathophysiology of PHN and discusses proposed mechanisms of pain generation with emphasis on the various pharmacological treatments and invasive modalities currently available.

A Case of Drug-Induced Hypersensitivity Syndrome With Multiple Organ Involvement Treated With Plasma Exchange

A 53-year-old male patient began treatment for systemic exanthema with diaphenylsulfone (DHS) on 21 November 2002. On 18 December 2002, the patient developed a fever and additional systemic erythematous exanthema. Systemic lymphadenopathy, hepatosplenomegaly, leukocytosis (in particular, an increase in the number of atypical lymphocytes) and liver dysfunction followed. After cessation of the DHS treatment on 25 December 2002, acute renal failure occurred and the patient was transferred to Shinshu University Hospital on 4 January 2003. The patient was diagnosed with drug-induced hypersensitivity syndrome (DIHS). Steroid pulse therapy (methylprednisolone 1000 mg/day for 3 days) was given, followed by 60 mg/day of prednisolone. The patient's renal functions recovered and he was taken off hemodialysis therapy. However, the patient relapsed twice despite two sessions of steroid pulse therapy and an increase in the dose of prednisolone to 100 mg/day. Plasma exchange (PE) was carried out to reduce the activity of the disease. With a total of four plasma exchanges, we were able to reduce the dose of prednisolone from 100 mg/day to 60 mg/day without relapse. There were no adverse effects from the plasma exchanges. Plasma exchange should be considered in the treatment with corticosteroid-resistant DIHS with multiple organ lesions.

Digital Skin Blood Flow as an Indicator for Intravascular Injection of Epinephrine-Containing Simulated Epidural Test Dose in Sevoflurane-Anesthetized Adults

I designed this study to determine the efficacy of heart rate (HR), systolic blood pressure (SBP), and digital skin blood flow (DSBF) in detecting intravascular injection after a simulated epidural test dose containing 15 mug of epinephrine in sevoflurane-anesthetized adults. In addition, the testing threshold using DSBF was derived. Eighty patients were randomized to receive either 0.5 minimum alveolar anesthetic concentration (MAC) sevoflurane or 1.0 MAC sevoflurane and nitrous oxide in oxygen (n = 40 for each sevoflurane concentration). Each group of patients was further randomized to receive either 3 mL of 1.5% lidocaine containing 15 mug of epinephrine IV or 3 mL of saline IV (n = 20 each). HR, SBP, and DSBF were monitored for 5 min after injection. By using the HR (positive if >or=10 bpm increase) and SBP (positive if >or=15 mm Hg increase) criteria, a positive response rate to epinephrine was 95% for both variables during 0.5 MAC and 90% during 1.0 MAC sevoflurane anesthesia. Injection of the test dose resulted in peak DSBF decrease by 87% +/- 8% and 81% +/- 12% at 52 +/- 10 and 53 +/- 13 s in the sevoflurane 0.5 and 1.0 MAC groups, respectively. Positive DSBF criterion, as determined from peak increases during saline administration, was a decrease in DSBF >or=15%. Using this value, the sensitivity, specificity, positive predictive value, and negative predictive value were 100% in both sevoflurane groups. In conclusion, DSBF was superior to conventional hemodynamic criteria for detection of an intravascular injection of epidural test dose.

IMPLICATIONS

This study examined the efficacy of digital skin blood flow to detect an intravascular injection of an epinephrine-containing epidural test dose. This new variable when measured with a laser Doppler flowmeter was superior to conventional hemodynamic criteria during sevoflurane anesthesia.

Treatment of postherpetic neuralgia

Postherpetic neuralgia (PHN) remains one of the most troublesome common chronic neuropathic pain conditions. Many controlled trials have been published showing good efficacy and reasonable tolerability. These include gabapentinoids, opioids, tricyclic antidepressants, and topical lidocaine and capsaicin. Combination therapies are possible, but have not been proven, and long-term follow-up is limited. Only few case series exist for surgical and other invasive therapies and their role remains uncertain.

Safety and immunogenicity of gelatin-free varicella vaccine in epidemiological and serological studies in Japan

Following gelatin-containing varicella vaccine (1994-1999: 1,410,000 distributed doses), 28 serious anaphylactic reactions and 139 non-serious allergic reactions were reported, with no serious and only five non-serious reactions following gelatin-free vaccine (1999-2000: 1,300,000 distributed doses). All nine sera available from children with serious reactions tested positive for gelatin-specific IgE, whereas 55 of the 70 available from those with non-serious reactions were positive, with one false positive. There was no correlation between gelatin-specific IgE antibody titers and severity of allergic reaction. Post-immunization anti-varicella antibody titers were comparable for both gelatin-free and gelatin-containing vaccine groups. The new gelatin-free varicella vaccine is thought to be safe, with similar immunogenicity to the earlier gelatin-containing vaccine.

Optimum pain relief with continuous epidural infusion of local anesthetics shortens the duration of zoster-associated pain

OBJECTIVE

To investigate effects of continuous epidural infusion (CEI) of 0.5% bupivacaine added to intermittent epidural boluses (IEB) on the duration of zoster-associated pain (ZAP), as compared with continuous infusion of normal saline placebo added to IEB.

DESIGN

A prospective, double-blind, randomized, placebo-controlled study.

SETTING

A university hospital and an affiliated clinic in Japan from 1996 through 1999.

PATIENTS

56 immunocompetent herpes zoster (HZ) patients, 50 years or older, within 10 days of rash onset and with severe pain and eruption.

INTERVENTIONS

Patients were hospitalized and randomly allocated into 2 groups. CEI group given CEI of 0.5% bupivacaine (0.5-1.0 mL/h) plus IEB of 0.5% bupivacaine 4 times daily (n = 29). IEB group given normal saline infusion plus IEB of 0.5% bupivacaine 4 times daily (n = 27). All patients received oral acyclovir 800 mg, 5 times daily, for 7 days.

OUTCOME MEASURES

The number of days required for complete cessation of ZAP and the proportion of subjects with allodynia beyond 30 days.

RESULTS

The median time to cessation of ZAP was significantly shorter in the CEI group than in the IEB group (29 days vs. 40 days, P = 0.002). The number of patients whose allodynia persisted beyond 30 days of treatment was significantly lower in the CEI group than in the IEB group (10% vs. 37%, P = 0.027).

CONCLUSIONS

CEI of 0.5% bupivacaine plus IEB was associated with a shorter duration of ZAP and fewer patients with allodynia beyond 30 days, compared with IEB plus normal saline infusion. Patients at high risk for developing postherpetic neuralgia (PHN) can be managed with intensive therapies at the early stage of disease, such as CEI, which maintains effective analgesia and may reduce the burden of PHN.

Effectiveness of live varicella vaccine

The disease burden of chickenpox to children has been described, and a lower force of neutralising antibody to varicella-zoster virus (VZV) than against measles, either after natural infection or after vaccination, has been reported. In the case of VZV, strong cell-mediated immunity may work efficiently to prevent the spread of the virus. The lower force of humoral antibody to VZV might be related to the occurrence of "breakthrough" varicella cases in a small portion of the vaccine recipients. Safety and high effectiveness of the varicella vaccine--approximately 85% effective for all diseases and 95-100% effective for moderate-to-severe diseases--have been reported. Vaccine-induced immunity persists for 10-20 years. However, concerns have been raised that universal immunisation in children may shift the susceptibility from children to adults, whose symptoms are usually moderate-to-severe. In addition, other concerns have been expressed that, due to lack of exposure to varicella in children, the elderly may develop zoster infections more frequently than before. A clear answer is difficult to give at present, although, for several reasons, such situations may be unlikely to occur.

Risk factors for postherpetic neuralgia in patients with herpes zoster

OBJECTIVES

To identify risk factors for postherpetic neuralgia (PHN) using a validated definition of this chronic neuropathic pain syndrome, to determine combinations of risk factors that identify patients with a high risk of developing PHN, and to examine the characteristics of patients with subacute herpetic neuralgia, that is, pain that persists beyond the acute phase of herpes zoster but that resolves before PHN can be diagnosed.

METHODS

The authors examined baseline and follow-up data from 965 herpes zoster patients enrolled within 72 hours of rash onset in two clinical trials of famciclovir.

RESULTS

Univariate and multivariate analyses indicated that older age, female sex, presence of a prodrome, greater rash severity, and greater acute pain severity made independent contributions to identifying which patients developed PHN. Patients with subacute herpetic neuralgia who did not develop PHN were significantly younger and had less severe acute pain than PHN patients but were significantly more likely to have severe and widespread rash than patients without persisting pain.

CONCLUSIONS

The independent contributions to the prediction of PHN made by older age, female sex, presence of a prodrome, greater rash severity, and greater acute pain severity suggest that these risk factors reflect different mechanisms that each contribute to the development of PHN. Subacute herpetic neuralgia that does not progress to PHN may reflect peripheral tissue damage and inflammation caused by a particularly severe or widespread rash.

Cerebrospinal fluid interleukin 8 concentrations and the subsequent development of postherpetic neuralgia

PURPOSE

Other than age, the risk factors for postherpetic neuralgia are not well established. We studied whether the concentration of interleukin 8 in the cerebrospinal fluid is associated with the risk of postherpetic neuralgia.

METHODS

We enrolled 170 patients more than 50 years old who had a typical painful and nontrigeminal herpetic rash. Patients were treated with acyclovir; no corticosteroids were given. Cerebrospinal fluid was taken for analysis of interleukin 8 during and at full crusting of the herpetic rash. Age, sex, comorbid conditions, prodromal pain, localization and severity of herpetic rash, number of skin lesions, and degree of pain were recorded. We used multivariate logistic regression modeling to identify significant predictive factors. Receiver operating characteristic (ROC) curves were evaluated to determine the contribution of each factor.

RESULTS

Six months after healing, 31 patients (18%) had postherpetic neuralgia; 27 patients still had it after 1 year. Only three variables-age (odds ratio [OR] = 2.7 per 10-year increase; 95% confidence interval [CI]: 1.2 to 6.2), acute pain (OR = 1.8 per unit increase in visual analog scale; 95% CI: 1.2 to 2.8), and interleukin 8 concentration in the cerebrospinal fluid at full crusting of the herpetic rash (OR = 1.6 per 20-microg/L increase; 95% CI: 1.3 to 2.0)-were significant predictors of postherpetic neuralgia at 1 year. Interleukin 8 concentration also had the highest area under the ROC curve at these evaluation points (P <0.001).

CONCLUSION

Our results suggest that interleukin 8 concentration in the cerebrospinal fluid at full crusting of herpetic rash may be useful for identifying patients who are likely to develop intractable postherpetic neuralgia.

Factors influencing the features of postherpetic neuralgia and outcome when treated with tricyclics

This paper retrospectively reviews features of postherpetic neuralgia (PHN) in up to 279 personal patients in relation to treatment outcome when treated with tricyclic antidepressants (TCAs). Factors affecting characteristics of PHN: (i) Patients with allodynia (89%) and/or burning pain (56%) have a much higher visual analogue pain intensity score than those without; (ii) Acyclovir (ACV) given for acute shingles (HZ) does not reduce the incidence of subsequent PHN, but reduces the pain intensity in PHN patients with allodynia; (iii) ACV given for acute HZ reduces the incidence of burning pain in subsequent PHN, but not of allodynia; (iv) ACV given for acute HZ reduces the incidence of clinically detectable sensory deficit in subsequent PHN. Factors affecting outcome of TCA-treated PHN: (i) The point in time at which TCA treatment is commenced is by far the most critical factor: started between 3 and 12 months after acute HZ onset, more than two-thirds obtain pain relief (NNT=1.8); between 13 and 24 months, two-fifths (41%) (NNT=3.6); and more than two years, one-third (NNT=8.3). Background and paroxysmal pain disappear earlier and are more susceptible of relief than allodynia. (ii) Twice as many (86%) of PHN patients without allodynia obtain pain relief with TCA treatment than those with (42%); (iii) the use of ACV for acute HZ more than halves the time-to-relief of PHN patients by TCAs; (iv) PHN patients with burning pain are significantly less likely to obtain pain relief with TCAs than those without (p<0.0001).

Intrathecal fentanyl added to intrathecal bupivacaine for day case surgery: a randomized study

BACKGROUND AND OBJECTIVE

The implication of intrathecal lidocaine in neurological toxicity has made intrathecal bupivacaine the commonly used drug for local anaesthesia in ambulatory surgery. However, in high doses intrathecal bupivacaine may produce a high level of sensory and motor block, and arterial hypotension; discharge from hospital may be delayed. Intrathecal opioids added to low-dose local anaesthetics produce a synergistic effect without increasing the sympathetic block or delaying discharge. The aim of our study was to identify the minimum effective dose of intrathecal fentanyl that in combination with low-dose intrathecal bupivacaine would provide adequate surgical conditions without prolonging recovery.

METHODS

A prospective, single, blind, randomized study was conducted in 45 adult males scheduled for minor urological procedures using intrathecal anaesthesia on a day care basis. Patients were randomly assigned to one of three groups (n = 15 each). They received bupivacaine 0.17% 5 mg--with either fentanyl 7.5 microg (fenta-7.5), 10 microg (fenta-10) or 12.5 microg (fenta-12.5) intrathecally in a total volume of 3 mL. The quality of anaesthesia, haemodynamic stability, time to two-segment and S2 regression, time to micturition, and time to discharge were assessed.

RESULTS

The time to two-segment regression and S2 regression with fenta-12.5 was significantly longer than with fenta-7.5 and fenta-10 (P < 0.01). Fenta-7.5 had a significantly higher number of failed blocks (four patients) compared with fenta-12.5 (P < 0.05). The time out of bed, time to micturition and time to discharge were significantly longer with fenta-10 and fenta-12.5 compared with fenta-7.5, and also with fenta-12.5 compared with fenta-10 (P < 0.01). Haemodynamic stability did not differ for all the drug combinations.

CONCLUSIONS

Fentanyl 12.5 microg added to low-dose bupivacaine (5 mg) intrathecally provides better surgical anaesthesia and increased reliability of block than intrathecal fentanyl 7.5 or 10 microg. Haemodynamic stability was the same for all dose combinations used.

Important physical principles in anaesthesiology

The aim of this Review is to introduce anaesthesiologists to the basic physical principles that are important for their work. A better understanding of the underlying processes during anaesthesia is required for greater safety and efficiency. Relevant physical quantities are presented along with the area of anaesthesiology where they are used. This approach provides better targeting to the needs of practising anaesthesiologists. This text has been a part of a specialist course in anaesthesiology at the University of Ljubljana for some years. Current results show that both the students and the specialist anaesthesiologists now show a better understanding of the underlying physical principles required for their work and are more successful in fulfilling the needs of their practical work.

High-dose midazolam and the attenuation of the contractile response to vasoconstrictors in coronary artery segments

BACKGROUND AND OBJECTIVE

Benzodiazepines may cause hypotension and are reported to interfere with smooth vascular muscle activity. The aim was to elucidate the influence of three different benzodiazepines on the vascular reactivity of coronary arteries.

METHODS

Using the model of isolated vessels, we studied the impact of midazolam (0.15, 1.5, 15 microg mL(-1)), diazepam (0.1, 1.0, 10 microg mL(-1)) and flunitrazepam (0.01, 0.1, 1.0 microg mL(-1)) on the contractile responses to histamine (2 x 10(-5) mol L(-1)) and serotonin (3 x 10(-5) mol L(-1)) in isolated intact and denuded coronary arteries.

RESULTS

Midazolam significantly attenuated the contractile response when administered in high concentrations (15 microg mL(-1)). This effect was more pronounced in intact than in denuded preparations (histamine: -22.7 versus -7.3%, P = 0.0079; serotonin: -47.1 versus -15.9%, P < 0.0001). Diazepam and flunitrazepam exerted no significant effects on the vascular tone of coronary arteries.

CONCLUSIONS

Midazolam, but not diazepam or flunitrazepam, attenuates the contractile responses to vasoconstrictors in concentrations beyond those used in clinical practice. This effect is in part mediated by endothelial factors.

Anaesthesia for day case surgery: a survey of adult clinical practice in the UK

BACKGROUND AND OBJECTIVE

In October 2000, we conducted a national postal survey of consultant day case anaesthetists in the UK to explore the range and variation in the practice of anaesthetizing a patient for day case surgery (paediatrics, urology and orthopaedics). The survey was carried out as part of a larger study that comprised a major two-centre randomized controlled trial designed to investigate the costs and outcome of several anaesthetic techniques during day care surgery in paediatric and adult patients (cost-effectiveness study of anaesthesia in day case surgery). We report the findings of this national survey of adult urology and orthopaedic day case anaesthetic practice in the UK.

METHODS

The survey used a structured postal questionnaire and collected data on the duration of the surgical procedure; the use of premedication; the anaesthetic agents used for induction and maintenance; the fresh gas flows used for anaesthesia; the use of antiemetics; and the administration of local anaesthesia and analgesia.

RESULTS

The overall response rate for the survey was 74% (63% for urology, 67% for orthopaedics). The survey indicated the following practice in adult urology and adult orthopaedic day case surgery: 6 and 12% used premedication; propofol was the preferred induction agent (96 and 97%) and isoflurane the preferred maintenance agent (56 and 58%); 32 and 41% used prophylactic antiemetics; 86 and 93% used a laryngeal mask.

CONCLUSIONS

This survey identifies the variation in current clinical practice in adult day surgery anaesthesia in the UK and discusses this variation in the context of current published evidence.

Effect of dexamethasone on motor brachial plexus block with bupivacaine and with bupivacaine-loaded microspheres in a sheep model

BACKGROUND AND OBJECTIVE

It has been suggested that dexamethasone potentiates the sensory block produced by bupivacaine when both drugs are loaded in microspheres. The aim of the study was to evaluate the effect of dexamethasone on the brachial plexus block obtained with plain bupivacaine and bupivacaine-loaded microspheres.

METHODS

Dexamethasone alone (Group 5) or added to plain bupivacaine (75 mg) with (Groups 3 and 4) and without pH correction (Group 2) was compared with plain bupivacaine (75 mg; Group 1). The effect of a small dose of dexamethasone (0.42 mg) was then evaluated on the brachial plexus block obtained with bupivacaine (750 mg) as bupivacaine-loaded microspheres (Group 6). Dexamethasone was added either in the suspending medium (Group 7) or incorporated with bupivacaine into microspheres (Group 8). The motor block was evaluated in a plexus brachial sheep model.

RESULTS

Dexamethasone alone did not produce any motor block. When added to plain bupivacaine without pH correction, complete motor block could not be obtained. When the pH was corrected, addition of dexamethasone to plain bupivacaine seemed to delay the onset of motor block and did not prolong its duration, and it had no effect on the pharmacokinetics of bupivacaine. With bupivacaine-loaded microspheres, the duration of complete motor block was reduced when a small dose of dexamethasone was added in the suspending medium. However, the duration of motor block was significantly prolonged when dexamethasone was incorporated with bupivacaine into microspheres.

CONCLUSIONS

Despite the delayed onset of motor block, the incorporation of dexamethasone in bupivacaine-loaded microspheres dramatically increases the duration of action (700 +/- 485-5160 +/- 2136 min), which could be clinically relevant when such a drug-delivery system will be available.