Factors influencing the choice of anesthetic technique for primary hip and knee arthroplasty.

Despite evidence in the literature, continuing wide variation exists in anesthetic technique for primary joint arthroplasties. Recent evidence suggests that neuraxial anesthesia has advantages over general anesthesia in terms of mortality, major morbidity and healthcare utilization. Yet, despite the proposed benefits, utilization of these two techniques varies greatly across geographical locations, with general anesthesia being most common for total hip arthroplasty (THA) and total knee arthroplasty (TKA) in parts of the world. We uncover some factors that promote or hinder the use of neuraxial anesthesia in THA and TKA. Healthcare professionals should be familiarized with the evidence for neuraxial anesthesia, and unbiased educational material should be developed for patients regarding anesthetic options for THA and TKA in order to promote best practice.

Provocative dose of methacholine causing a 20% drop in FEV1 should be used to interpret methacholine challenge tests with modern nebulizers.

RATIONALE: The American Thoracic Society guidelines (1999) for methacholine challenge tests (MCTs) using the 2-minute tidal breathing protocol were developed for the now-obsolete English-Wright (EW) nebulizer. In addition, the guideline recommendation to use the provocative concentration of methacholine causing a 20% drop in FEV1 (PC20) rather than the provocative dose of methacholine causing a 20% drop in FEV1 (PD20) for determining the level of bronchial hyperresponsiveness has been challenged. OBJECTIVES: To determine if cumulative dose or concentration of methacholine delivered to the airways is the determinant for airway responsiveness and to validate use of the AeroEclipse* II BAN (Aero; Trudell Medical International, London, ON, Canada) nebulizer compared with use of the reference standard EW nebulizer. METHODS: Subjects with asthma (10-18 yr old) participated in randomized, controlled cross-over experiments comparing four MCT protocols using standard methacholine concentrations, but varying: (1) methacholine starting concentration (testing for cumulative effect); (2) nebulizer (EW versus Aero); and (3) inhalation time. PD20 was calculated using nebulizer output rate, inhalation time, and preceding doses delivered. ANOVA analyses were used to compare geometric means of PC20 and PD20 between protocols. RESULTS: A total of 32 subjects (17 male) participated. PC20 differed when starting concentration varied (0.46 vs. 0.80 mg/ml; P<0.0001), whereas PD20 did not (0.06 vs. 0.08 mg). PC20 differed with the EW versus the Aero nebulzer with 30-second inhalation (1.19 vs. 0.43 mg/ml; P=0.0006) and the EW versus the Aero nebulizer with 20-second inhalation (1.91 vs. 0.89 mg/ml; P=0.0027), whereas PD20 did not (0.07 vs. 0.06 mg and 0.11 vs. 0.09 mg, respectively). CONCLUSIONS: In MCTs, the cumulative dose (PD20), not the PC20, determines bronchial responsiveness. Modern nebulizers may be used for the test if clinical interpretation is based on PD20. Clinical trial registered with www.clinicaltrials.gov (NCT01288482).

The role of molecular genetic analysis in the diagnosis of primary ciliary dyskinesia.

RATIONALE: Primary ciliary dyskinesia (PCD) is an autosomal recessive genetic disorder of motile cilia. The diagnosis of PCD has previously relied on ciliary analysis with transmission electron microscopy or video microscopy. However, patients with PCD may have normal ultrastructural appearance, and ciliary analysis has limited accessibility. Alternatively, PCD can be diagnosed by demonstrating biallelic mutations in known PCD genes. Genetic testing is emerging as a diagnostic tool to complement ciliary analysis where interpretation and access may delay diagnosis. OBJECTIVES: To determine the diagnostic yield of genetic testing of patients with a confirmed or suspected diagnosis of PCD in a multiethnic urban center. METHODS: Twenty-eight individuals with confirmed PCD on transmission electron microscopy of ciliary ultrastructure and 24 individuals with a probable diagnosis of PCD based on a classical PCD phenotype and low nasal nitric oxide had molecular analysis of 12 genes associated with PCD. RESULTS: Of 49 subjects who underwent ciliary biopsy, 28 (57%) were diagnosed with PCD through an ultrastructural defect. Of the 52 individuals who underwent molecular genetic analysis, 22 (42%) individuals had two mutations in known PCD genes. Twenty-four previously unreported mutations in known PCD genes were observed. Combining both diagnostic modalities of biopsy and molecular genetics, the diagnostic yield increased to 69% compared with 57% based on biopsy alone. CONCLUSIONS: The diagnosis of PCD is challenging and has traditionally relied on ciliary biopsy, which is unreliable as the sole criterion for a definitive diagnosis. Molecular genetic analysis can be used as a complementary test to increase the diagnostic yield.

Postoperative pain management after total knee arthroplasty in elderly patients: treatment options.

Total knee arthroplasty (TKA) is a common surgical procedure in the elderly and is associated with severe pain after surgery and a high incidence of chronic pain. Several factors are associated with severe acute pain after surgery, including psychological factors and severe preoperative pain. Good acute pain control can be provided with multimodal analgesia, including regional anesthesia techniques. Studies have demonstrated that poor acute pain control after TKA is strongly associated with development of chronic pain, and this emphasizes the importance of attention to good acute pain control after TKA. Pain after discharge from hospital after TKA is currently poorly managed, and this is an area where increased resources need to be focused to improve early pain control. This is particularly as patients are often discharged home within 4-5 days after surgery. Chronic pain after TKA in the elderly can be managed with both pharmacological and non-pharmacological techniques. After excluding treatable causes of pain, the simplest approach is with the use of acetaminophen combined with a short course of non-steroidal anti-inflammatory drugs (NSAIDs). Careful titration of opioid analgesics can also be helpful with other adjuvants such as the antidepressants or antiepileptic medications used especially for patients with neuropathic pain. Topical agents may provide benefit and are associated with fewer systemic side effects than oral administration. Complementary or psychological therapies may be beneficial for those patients who have failed other options or have depression associated with chronic pain.