Factors associated with failure of trigger point injections.

OBJECTIVE: The purpose of this study was to investigate factors that may influence the outcome of trigger point injections for myofascial pain syndrome. No prior studies have correlated preexisting factors with treatment outcome or assessed the magnitude of risk of treatment failure associated with such factors. DESIGN AND PATIENTS: Thirty-one factors derived from patient evaluation and physical examination were selected according to prior studies of mixed pain groups focusing on clinical importance and ease of assessment in a typical clinic setting. Included in the analysis were 193 patients who received trigger point injections and who completed baseline questionnaires. Factors were analyzed via univariate and logistic regression analyses both for independent association with short-term treatment outcome and for magnitude of risk of failure associated with each factor following adjustment for other factors. RESULTS: In univariate analysis an increased risk of treatment failure was associated with unemployment due to pain at the start of treatment, no relief from analgesic medication, constant pain, high levels of pain-at-its-worst and pain-at-its least, prolonged duration of pain, change in social activity, and lower levels of coping ability. Alcohol use was associated with a decreased risk of treatment failure. In logistic regression analysis, only lack of employment, prolonged duration, and change in social activity were independently associated with treatment outcome. Constant-versus-intermittent pain was included in the logistic model because there was an increase in risk that may be clinically important and because it influenced the effect of change in social activity. These results were not affected by the number or type of additional treatments the patients had. CONCLUSIONS: These results suggest that several factors should be considered in treating myofascial pain patients with trigger point injections, and this study supports the belief that pain is a multidimensional problem and that a variety of factors may influence treatment outcome.

Diltiazem and regional left ventricular function during graded coronary constriction and propofol anesthesia in the dog.

Although calcium channel blockers may preserve function in ischemic myocardium, they may also produce myocardial depression and dysfunction in the presence of decreased coronary flow. This study was designed to examine the issue of possible protection afforded by diltiazem against ischemia-induced myocardial dysfunction during propofol anesthesia. In eight anesthetized and ventilated dogs, regional myocardial (ultrasonic crystals in both left anterior descending [LAD] and left circumflex [LC] perfusion areas) and global ventricular function were evaluated during progressively severe degrees of myocardial ischemia (LAD constriction) before and after intravenous diltiazem (150 micrograms/kg). As coronary flow decreased, heart rate increased, and arterial and coronary perfusion pressures, left ventricular dP/dt, and cardiac output decreased. Systemic vascular resistance was unaffected. Diltiazem without coronary constriction increased heart rate, and decreased diastolic arterial pressures, left ventricular (LV) end-diastolic, coronary perfusion pressures, LV dP/dt max, LAD coronary blood flow, stroke volume, and cardiac output. At all levels of coronary constriction following diltiazem, there were decreases in systolic and diastolic arterial pressures, stroke volume, cardiac output, LV dP/dt, and coronary perfusion pressure. Heart rate increased at critical coronary constriction, and then remained constant relative to the prediltiazem state. The regional muscle effects of the reductions in coronary flow in the LAD perfusion territory included decreased systolic shortening and increased postsystolic shortening before and after diltiazem. Diltiazem did not alter the magnitude of the alterations in systolic or postsystolic shortening brought about by coronary constriction. No changes occurred in the LC area.(ABSTRACT TRUNCATED AT 250 WORDS)

Statistics: can we prove an association for a rare complication?

BACKGROUND AND OBJECTIVES: Microcatheters for continuous spinal anesthesia were withdrawn from the market after an apparent increase in the incidence of cauda equina syndrome (CES) associated with spinal anesthesia after introduction of these catheters. The objective of this review is to evaluate the historical data on CES after spinal anesthesia and to compare the result to the recent data. METHODS: The literature on the use of statistics and on complications associated with spinal anesthesia was reviewed. Poisson probabilities were calculated to assess the probability of seeing the recent cases of CES, given the historical data. The sample size required for a prospective study was calculated. RESULTS: Statistics cannot "prove" an hypothesis but can only support or fail to support it. Use and interpretation of the p value are discussed, as are possible problems with interpretation of the p value. The difference between causal and statistical inference is discussed. Probabilities for the occurrence of CES after microcatheter use were calculated. The sample size for a prospective study of this problem was calculated; a large sample is required. CONCLUSIONS: Statistics alone cannot support an association of microcatheters with CES after spinal anesthesia. Additional considerations suggest a possible association, but further study is required.

Factors associated with failure of lumbar epidural steroids.

BACKGROUND AND OBJECTIVES: The purpose of this study was to investigate factors that may influence the outcome of epidural steroid treatment for low back pain. Although the correlation of multiple factors with treatment outcome has been demonstrated, no previous studies have assessed the magnitude of risk of treatment failure associated with these factors. METHODS: Thirty-three factors derived from patient evaluation and physical examination were selected according to previous studies, clinical importance, and ease of assessment in a typical clinic setting. Two hundred nine patients were included in the analysis. Factors were analyzed by univariate and logistic regression analyses both for independent association with treatment outcome and for magnitude of risk of failure associated with each factor after adjustment for other factors. RESULTS: An increased risk of treatment failure was associated in univariate analysis with lower levels of education, smoking, lack of employment at start of treatment, constant pain, sleep disruption, nonradicular diagnosis, prolonged duration of pain, change in recreational activities, or extreme values on psychologic scales. Alcohol use was associated with decreased risk of treatment failure. With logistic regression analysis, only prolonged duration, nonradicular diagnosis, lack of employment, and smoking were independently associated with treatment outcome. CONCLUSIONS: These results suggest that several factors should be considered in treating patients with low back pain with epidural steroids. This study supports the belief that pain is a multidimensional problem and that a variety of factors may influence treatment outcome.

Canine end-systolic pressure-length relationships: depressed by diltiazem, invalidated by ischemia.

This study was designed to determine whether the end-systolic pressure-length relationship (ESPLR) reflects changes in regional contractility during the imposition of graded ischemia, and whether it is modified by diltiazem during propofol anesthesia. Seven beagles were anesthetized and instrumented to measure left ventricular pressure and subendocardial segment lengths (sonomicrometry) in the region of the left anterior descending (LAD) and circumflex (LC) arteries. Afterload was increased by the tightening of a snare around the descending thoracic aorta. Pressure-length loops were constructed and the slope of the ESPLR and the x-axis intercept, Lo, were calculated. Graded ischemia of the apical myocardium only was accomplished by the tightening of a micrometer-controlled snare around the LAD to produce Critical Constriction (CC), Ischemia 1 and 2 (I1, I2), and Total Occlusion (TO). In the basal LC region, LAD ischemia had no effect on either the ESPLR slope or Lo. In contrast, the ESPLR slope in the LAD area was decreased by ischemia at I1 (-40%), increased at TO (+69%), and unchanged at CC and I2, and was reduced by diltiazem at CC and I2 (-31% and -36%, respectively). The LAD ESPLR Lo was increased by ischemia by 64% and 61% at I2, and 91% and 122% at TO, before and after diltiazem, respectively. In the LC region, diltiazem decreased systolic shortening and the ESPLR slope. These results indicate that diltiazem has negative inotropic properties in both ischemic and nonischemic areas. Also, Lo is not a constant and must always be redetermined for every intervention. In the absence of ischemia, the ESPLR may be a reliable measure of myocardial contractility.(ABSTRACT TRUNCATED AT 250 WORDS)

Wisconsin physicians' knowledge and attitudes about opioid analgesic regulations.

This pilot study was designed to evaluate physician knowledge of the controlled substance regulations that govern the prescribing of opioids and whether concerns about regulatory scrutiny affect reported prescribing practices. Two hundred Wisconsin physicians were surveyed, and 90 (45%) of the questionnaires were evaluable. Approximately 50% of the responses to questions about controlled substance regulations were incorrect. Concern about regulatory scrutiny ranked low compared to concerns about addiction and other opioid side effects. However, 54% of the respondents indicated that, due to concern of regulatory scrutiny, they will do one of the following: reduce drug dose or quantity, reduce the number of refills, or choose a drug in a lower schedule. These results indicate that many physicians have poor knowledge of controlled substances regulations and that the perceived risk of regulatory scrutiny can alter physician prescribing practice. Implications for patient care, policy and further research are discussed.

Educational role of cancer pain rounds.

Lack of appropriate physician education is one of several reasons for the recognized deficits in cancer pain management. This article describes the educational role of a weekly meeting, "Cancer Pain Rounds," attended by a multidisciplinary team of health professionals skilled in cancer pain management and student physicians caring for inpatients with cancer. Educational benefits occur in three spheres including factual information concerning assessment, treatment, and attitude issues, legitimization of the cancer pain problem, and role modeling. This type of educational experience will hopefully improve cancer pain management.

Forehead pulse oximetry compared with finger pulse oximetry and arterial blood gas measurement.

Usual monitoring sites for pulse oximetry involve the fingers, toes, ear lobe, and nasal septum. This study examined the performance of a forehead sensor compared with a finger sensor for the pulse oximeter and arterial blood gas (ABG) analysis. Ten healthy adult volunteers and 22 ventilator-dependent patients were studied. The arterial oxygen saturation detected by forehead pulse oximetry (SpO2) correlated well with finger SpO2 and arterial oxygen saturation (SaO2) determined by arterial blood gas analysis in the healthy volunteers. Forehead SpO2 in mechanically ventilated patients correlated well with finger SpO2 and SaO2 when heart rate detected by pulse oximeter differed less than 10% from apical heart rate. Factors that caused a difference in oximeter-detected heart rate and apical heart rate were extensive tissue edema, head movement, and difficulty securing good tape placement. This suggests that when signal strength is weak, causing poor pulse rate detection, there will also be problems associated with accurate SpO2. The forehead pulse oximeter sensor works well on healthy, well-oxygenated volunteers. Difficulty was experienced when applying and using the sensor on critically ill patients. The reliability of the forehead pulse oximeter sensor has not been established at low saturations.