Neuropathic pain after orthopaedic surgery with continuous peripheral nerve block.

INTRODUCTION: Continuous peripheral nerve blocks (cPNBs) have shown favourable post-operative pain control results but may be associated with a risk for long-term neurological complications. This study sought to examine factors associated with persistent post-operative pain and potential neuropathy after orthopaedic lower-limb surgery with the use of post-operative cPNB. METHODS: Patients who underwent lower limb orthopaedic procedures with cPNBs between November 2021 to May 2022 were included. Patient demographics and perioperative data were noted. At discharge, patients completed the PainDetect (PD) questionnaire and were followed up six months after discharge. RESULTS: Seventy-seven patients with a total of 171 catheters completed the follow up. The median time to follow-up was 214 days after catheter removal, and 18 patients (23%) had a PD score ≥ 13. Univariate analysis showed that multiple variables were associated with a PD score ≥ 13 at the six-month follow-up. Multiple logistic regression showed that a high PD score at discharge, high BMI and longer duration of cPNBs were associated with higher risk of having a PD score ≥ 13 at the six-month follow-up. CONCLUSION: Several factors were associated with a higher risk of having possible neuropathy after six months. BMI, duration of catheter and PD score at discharge were correlated with risk of possible neuropathic pain. FUNDING: None. TRIAL REGISTRATION: The study was a quality control project and therefore did not require registration under Danish law.

Does the performance of lower limb peripheral nerve blocks differ among orthopedic sub-specialties? A single institution experience in 246 patients.

OBJECTIVES: Continuous peripheral nerve blocks (cPNBs) have shown promising results in pain management after orthopaedic surgeries. However, they can be associated with some risks and limitations. The purpose of this study is to describe our experience with the cPNBs regarding efficacy and adverse events in patients undergoing orthopedic surgeries on the lower extremity in different subspecialties. METHODS: This is a prospective cohort study on collected data from perineural catheters for pain management after orthopedic surgeries in lower limbs. Catheters were placed by experienced anesthesiologists using sterile technique. After an initial bolus dose of 10-20 mL ropivacaine 0.5% (weight adjusted), the catheters were secured and connected to disposable mechanical infusion pumps with ropivacaine 0.2% (basal infusion rate = 6 mL/h; weight adjusted (0.2 mL/kg/h)). After catheterization, the patients were examined daily, by specially educated acute pain service nurses. Pro re nata (PRN) or fixed boluses (10 mL bupivacaine 0.25%; weight adjusted) with an upper limit of 4 times/day, were administered if indicated. Patients' demographic data, physiological status, and pre-op intake of opioids and other analgesics were registered. The severity of post-operative pain was assessed with 'Numeric Rating Scale' (NRS) and 'Face, legs, Activity, Cry, Consolability' (FLACC) scale for adults and children, respectively. The need for additional opioids and possible complications were registered. RESULTS: We included 547 catheters of 246 patients (Range 1-10 catheters per patient). Overall, 115 (21%) femoral, 162 (30%) saphenous, 66 (12%) sciatic, and 204 (37%) popliteal sciatic nerve catheter were used. 452 (83%) catheters were inserted by a primary procedure, 61(11%) catheters employed as a replacement, and 34 catheters (6.2%) used as a supplement. For guiding the catheterization, ultrasound was applied in 451 catheters (82%), nerve stimulator in 90 catheters (16%), and both methods in 6 catheters (1.1%). The median duration a catheter remained in place was 3 days (IQR = 2-5). The proportion of catheters with a duration of two days was 81, 79, 73, and 71% for femoral, sciatic, saphenous, and popliteal nerve, respectively. In different subspecialties, 91% of catheters in wound and amputations, 89% in pediatric surgery, 76% in trauma, 64% in foot and ankle surgery, and 59% in limb reconstructive surgery remained more than two days. During first 10 days after catheterization, the proportion of pain-free patients were 77-95% at rest and 63-88% during mobilization, 79-92% of the patients did not require increased opioid doses, and 50-67% did not require opioid PRN doses. In addition to 416 catheters (76%), which were removed as planned, the reason for catheter removal was leaving the hospital in 27 (4.9%), loss of efficacy in 69 (13%), dislodgement in 23 (4.2%), leakage in 8 (1.5%), and erythema in 4 catheters (0.73%). No major complication occurred. CONCLUSIONS: After orthopaedic procedures, cPNBs can be considered as an efficient method for improving pain control and minimizing the use of additional opioids. However, the catheters sometimes might need to be replaced to achieve the desired efficacy.

Propranolol in human plasma and breast milk.

To assess the problem of continuing propranolol therapy in a breast-feeding mother, studies were performed to determine simultaneously plasma and breast milk concentrations of propranolol after single dose (40 mg) and continuous dose (40 mg 4 times daily) treatment with this drug. Breast milk and plasma concentrations of propranolol peaked between 2 and 3 hours after dosing. Propranolol concentrations in breast milk were less than 40 and 64 percent, respectively, of peak plasma propranolol concentrations after single dose and continuous dose administration. It was estimated that the maximal cumulative propranolol load to this breast-feeding infant, consuming 500 ml of whole milk, when the mother received 40 mg of propranolol 4 times daily would be 21 microgram/24 hours. This dose is considerably less than the usual therapeutic dose of propranolol for infants.

Isolation and identification of a metabolite of haloperidol.

A new metabolite of haloperidol, formed by what is equivalent to the reduction of the carbonyl group to the alcohol, has been identified in human serum, liver and urine. The isolation and chromatographic behavior of the compound are discussed.

Enzyme immunoassay, liquid chromatography, and spectrofluorometry compared for the determination of procainamide and N-acetylprocainamide in serum.

Procainamide, an antiarrhythmic drug, and its biologically active metabolite, N-acetylprocainamide, were quantitated in serum by a commercially supplied enzyme immunoassay procedure. Replicate analyses of controls resulted in within-assay and between-assay coefficient of variation (CV) of less than 10%. Regression analyses of serum samples analyzed by immunochemical (y) and chromatographic or spectrofluorometric methods (x) gave equations with a slope of 0.99 to 1.11, y-intercept of -0.52 to -0.02, and correlation coefficient greater than 0.92. Clinical evaluation of the results indicates the respective enzyme immunoassay to be specific and sensitive for procainamide and N-acetylprocainamide. Immunochemical selectivity of the respective assay was quantitated by challenging the assay with other drugs. When the antibody reagent was crossreactive toward the other drugs, selectivity was determined to be inversely related to the concentration of the other drug.

Service needs of families where one parent has an affective illness: implications for service, education, and policy.

This study explored the service needs of families with a parent with an affective illness. Focus-group and individual interviews were conducted at selected locations across Canada with individuals who had an affective disorder, their partners, and their adult children. A total of 67 participants were recruited. Corresponding service providers were mailed a questionnaire which asked information regarding these families' needs, the service provider's role with these families, and what prevented or assisted them in addressing those needs. A total of 419 service providers participated in the study. There was congruence between family-identified needs and the needs identified by service providers. However, there remains a large disparity between the knowledge of needs and having these needs met. The results of this study identify the gaps in service provision and make recommendations for changes in the areas of service, education, and policy-making.

Enzyme immunoassay and two fluorometric methods compared for the determination of quinidine in serum.

Quinidine, an antiarrhythmic drug, was quantitated in serum by a commercially supplied enzyme immunoassay procedure (EMIT). Replicate analyses of serum controls resulted in a within-assay coefficient of variation of less than or equal to 10% and a between-assay coefficient of variation of less than or equal to 7%. Patient quinidine results by enzyme immunoassay were compared to those obtained by a non-selective (protein precipitation) and a selective (solvent back-extraction) fluorometric method. Assay selectivity for quinidine versus other drugs and versus the 3-hydroxy metabolite of quinidine was determined. Clinical evaluation of the results indicates the enzyme immunoassay technique to be sensitive for quinidine and more selective than commonly used fluorometric methods relying on back-extraction or protein precipitation.

Enzyme immunoassay of disopyramide in serum.

Disopyramide, an antiarrhythmic drug, was quantitated in serum by a commercially supplied enzyme immunoassay procedure. Replicate analyses of serum controls resulted in a within-assay coefficient of variation of less than or equal to 5% and a between-assay coefficient of variation of less than or equal to 7%. Regression analysis of 105 serum samples analyzed by this technique (y) and by gas chromatography (x) gave the equation y = 0.99x + 0.04 (r = 0.97). Clinical evaluation of the results indicates the enzyme immunoassay technique to be highly specific and sensitive for disopyramide. The selectivity of the assay vs other drugs has been determined.

Analytical toxicology: Applications of element-selective electrolytic conductivity detection for gas chromatography.

We applied a commercially available microelectrolytic conductivity detector to toxicological problems of qualitative and quantitative analysis by gas chromatography. The detector can be used for the sensitive and selective detection of halogen-, nitrogen-, and sulfur-containing compounds. Relative response in different element-selective detector variables such as reaction gas, reaction catalyst, and furnace temperature can be used to further improve qualitative identification by gas chromatography.

Decreased susceptibility of Malassezia furfur to UV light by synthesis of tryptophane derivatives.

Recently, tryptophane (Trp)-dependent synthesis of pigments and fluorochromes in Malassezia furfur was described. The possible significance of this metabolic pathway for the microorganism remains to be explored. Since the upper parts of the human epidermis are a natural habitat of M. furfur, increased exposure to UV light may be hazardous. Five reference strains and one wild type strain of M. furfur were grown on m-Dixon agar, in which the nitrogen source peptone had been substituted either by pigment-inducing tryptophane or arginine. The yeast cells thus obtained were harvested after 6 days, washed with physiological saline and inoculated on to the modified Dixon medium. Immediately after inoculation, the yeast cells were irradiated with UVA (100, 150 and 200 Jcm-2, single dose) or UVB (100, 500, 1000, 1500, 2000 mJcm-2, single dose; 500, 1500, 2500 mJcm-2 cumulative dose). Irrespective of the primary nitrogen source (Trp or Arg), unexposed controls showed nearly identical cell yield after 5 days. In the case of irradiation, however, growth reduction of cells cultured on Trp was lesser than that of cells fed with arginine. High significance (p < 0.0001) was found especially with the upper UVA and UVB doses. Differences were also found among the individual test strains, the wild strain being most sensitive. One strain (CBS 6094) failed to produce pigment on Trp medium, and there were no differences in the growth behavior of subcultures of this strain fed with either arginine or tryptophane under irradiation. In conclusion, synthesis of pigments and fluorochromes by M. furfur implies the generation of potent UV filters in the UVA and UVB spectrum.

Quantitation of 3'-hydroxypentobarbital in serum using high-performance liquid chromatography.

A quantitative method for the determination of 3'-hydroxypentobarbital (3'HP) in serum has been developed using reversed-phase high-performance liquid chromatography. A sensitivity limit of 0.5 micrograms/ml in 100 microliters serum was obtained by detection at 215 nm. Serum concentrations of 3'HP were measured in patients receiving high-dose pentobarbital therapy and pentobarbital:3'HP concentrations are discussed.

Analysis of medazepam, diazepam, and metabolites in plasma by gas-liquid chromatography with electrolytic conductivity detection.

An improved electrolytic conductivity detector allowed the gas-liquid chromatographic analysis of medazepam, diazepam, and major metabolites in 2 ml plasma at concentrations of 20 microgram/l. The detector had a sensitivity limit of less than 1 ng (or 100 pg nitrogen) when operated in the nitrogen-selective mode and a nitrogen/carbon elemental selectivity ratio of greater than 100,000 compared to octadecane and cholesterol. Detector response when operated in various element-selective chemical modes was investigated, and its application to the analysis of the title compounds was compared to electron capture and flame ionization detection systems.

The electrolytic conductivity detector as an element-selective gas chromatographic detector.

The response and elemental selectivity of the electrolytic conductivity detector (E1CD) to nitrogen-, chlorine-, and sulfur-containing compounds has been investigated as a function of chemical structure, furnace chemistry conditions (i.e., reaction gas, furnace temperature, catalyst, and post-furnace chemical abstractors), and solubilization-and-ionization processes (electrolytic chemistry and electrolytic conductance). The "profiling" of detector response for the gas-liquid chromatographic-E1CD analysis of selected compounds under defined furnace chemistry reaction conditions and electrolytic chemistry included the determination of detector signal to noise ratio, peak tailing, and elemental selectivity. Detector response and conductivity phenomena are discussed in terms of gas-phase furnace chemistry reactions, post-furnace reaction or abstraction processes, and solution-phase ionization and neutralization processes occurring in the conductivity cell.

Reactivity of EMIT serum barbiturate assay reagents: potential application for the quantitation of selected barbiturates.

The reactivity of EMIT serum barbiturate assay reagents toward barbiturate test compounds was investigated. Reactivity was determined by the C5 substituents on the barbiturate ring and O/S substitution (barbituric/thiobarbituric acid derivatives). Reagents were more reactive toward a 5,5-substituted barbiturate than toward its hydroxylated analogue. EMIT reactivity could be linearized vs. concentration of test compound, allowing for quantitative analysis in serum or plasma.

Exclusion of close linkage between the parathyroid hormone gene and a mutant gene locus causing idiopathic hypoparathyroidism.

A family is presented in which the mother has transmitted primary hypoparathyroidism with early onset and serum PTH (44-68) and C terminal deficiency to her two sons. Restriction enzyme analysis of allelic variation at the PTH gene locus revealed that the disease and the PTH alleles segregate independently. It is therefore concluded that the primary molecular defect leading to this form of hypoparathyroidism is not located within the PTH gene itself.

Enzyme immunoassay and gas--liquid chromatography compared for determination of lidocaine in serum.

Lidocaine, an anti-arrhythmic drug, was quantitated in serum by a commercially supplied enzyme immunoassay procedure. Replicate analyses of serum controls resulted in a within-assay coefficient of variation of less than 5.0 and a between-assay coefficient of variation of less than 6.5. Regression analysis of 87 serum samples analyzed by this technique (y) and by gas-liquid chromatography (x) gave the equation y = 0.96x - 0.03 (r = 0.99). Clinical evaluation of the results indicates the enzyme immunoassay technique to be highly specific and sensitive for lidocaine.