Assessment of Patient Preference for Constant Voltage and Constant Current Spinal Cord Stimulation

Objectives: Spinal cord stimulation devices control energy by generating either constant voltage (CV) pulses or constant current (CC) pulses. This study aimed to investigate: 1) whether patients feel differences between CV and CC stimulation; 2) if patients prefer CV or CC stimulation. Methods: Fourteen patients blinded to the type of pulse generation received 20 randomized pairs of 15‐sec pulse trains (CC‐CV, CV‐CC, CV‐CV, or CC‐CC). Patients identified whether the pairs were the same or different, and if they preferred the first or second train. Results: There was no difference in charge‐per‐pulse input between CV and CC modes. Patients performed at chance level in identifying identical pairs (55.7 ± 24.1% correct, 10 trials), and slightly better in identifying different pairs (67.1 ± 25.2% correct, 10 trials). No patients correctly identified all pairs. Patients were categorized based on their performance in this task. Only three patients fell into a category where preference could be established with some confidence with respect to the group averages. Two of these patients preferred CV, while one patient preferred CC. Conclusion: The lack of patient ability to discriminate in this preliminary investigation suggests that patient preference for a stimulation type should not be the key determining factor in choosing a spinal cord stimulation system.     

Elevated urinary levels of kidney injury molecule-1 among Chinese factory workers exposed to trichloroethylene

Epidemiological studies suggest that trichloroethylene (TCE) exposure may be associated with renal cancer. The biological mechanisms involved are not exactly known although nephrotoxicity is believed to play a role. Studies on TCE nephrotoxicity among humans, however, have been largely inconsistent. We studied kidney toxicity in Chinese factory workers exposed to TCE using novel sensitive nephrotoxicity markers. Eighty healthy workers exposed to TCE and 45 comparable unexposed controls were included in the present analyses. Personal TCE exposure measurements were taken over a 2-week period before urine collection. Ninety-six percent of workers were exposed to TCE below the current US Occupational Safety and Health Administration permissible exposure limit (100 ppm 8h TWA), with a mean (SD) of 22.2 (35.9) ppm. Kidney injury molecule-1 (KIM-1) and Pi-glutathione S transferase (GST) alpha were elevated among the exposed subjects as compared with the unexposed controls with a strong exposure-response association between individual estimates of TCE exposure and KIM-1 (P < 0.0001). This is the first report to use a set of sensitive nephrotoxicity markers to study the possible effects of TCE on the kidneys. The findings suggest that at relatively low occupational exposure levels a toxic effect on the kidneys can be observed. This finding supports the biological plausibility of linking TCE exposure and renal cancer.     

Metal Carbonyls in the Petroleum Industry

Industrial conditions which utilize temperature, pressure, and carbon monoxide in the presence of metal catalysts are conducive to metal carbonyl formation. An evaluation of the thermodynamic equilibrium data associated with metal carbonyls shows a definite relationship between these parameters which allow us to construct nomographs concerning their equilibrium formation. Metal carbonyls represent a distinct medical hazard. Recommendations for safe exposure limits and safety devices for personnel protection are based on the toxicity associated with metal carbonyls. Analytical methods indicate that adequate monitoring of the carbonyls of nickel, cobalt, and iron can be obtained.     

Paranasal sinusitis in burn patients following nasotracheal intubation.

Paranasal sinusitis is a complication of nasotracheal intubation. Of 99 nasally intubated adult patients who survived 48 hours after being burned, 22 who were intubated for more than 7 days underwent a computed tomographic scan of all paranasal sinuses, with timing dictated by the patient's clinical condition. Eight patients had computed tomographic and clinical findings consistent with sinusitis. Treatment consisted of removal of all nasal tubes, oral and topical nasal decongestants, and, when appropriate, culture-specific antibiotics. A subgroup of patients with preexisting sinus disease made up 50% of the patients with sinusitis; early conversion to an oral airway or a tracheostomy should be considered in such patients. Only one patient required surgical drainage of the sinuses. The frequency and morbidity of sinusitis in nasotracheally intubated burn patients does not justify the risk of routine conversion to an oral airway.     

The importance of accurate dosage of topical agents: a method of estimating involved area and application to calcipotriol treatment failures

Little attention is given to accurate dosage of topical medication which is a potential source of side-effects and treatment failure. There are studies on the dosage for 'sparing' application relevant to topical steroids but not for 'liberal' application. Though calcipotriol is a first line topical treatment for psoriasis, approximately one-third of patients do not respond adequately. The aims of the present study were to define liberal dosage, to develop a method of calculation of area of involved skin and to evaluate the efficacy of calcipotriol in optimized liberal dosages, based on preliminary studies, in calcipotriol treatment failures. Weight/unit area of ointment and cream base, constituting liberal application, was determined in six normal volunteers. The area of psoriatic involvement in 24 calcipotriol non-responders was estimated by a 'fill-up' method and a modified 'hand' method. The results of the two methods were similar (Pearson correlation coefficient 0.68, P < 0.0001) but the 'hand' method proved easier in use and was the preferred method for the rest of the study. The patients applied calcipotriol at their accustomed rates for at least 2 weeks and then at the calculated liberal rates, using cream in the morning and ointment at night, for 4 weeks. The efficacy measures were Psoriasis Area and Severity Index (PASI) (primary measure), a four-point efficacy score and a visual analogue scale. As a result of the preliminary study and the actual amounts used by the patients in the psoriasis treatment study reported below, liberal application has been defined as 50 g/m2 per application for ointment base and 40 g/m2 per application for cream. At this dosage, an average individual would use approximately 100 g of medication/week to treat 10% of the body surface. During the 4-week treatment study, the psoriasis patients used an average of 39 g (SD 17 g)/m2 per application of cream and 52 g (SD 13 g)/m2 per application of ointment. All efficacy measures showed marked improvement (P < 0.0001). The frequency distribution of the PASI reduction defined responsive (70% of patients) and poorly responsive groups (30%), with mean PASI reduction of 60% and 17%, respectively.