Prolonged opioid use after knee arthroscopy in military veterans.

BACKGROUND: Chronic postoperative pain occurs with an appreciable incidence after elective surgery. Known risk factors include perioperative pain and posttraumatic stress disorder (PTSD). Military veterans are a population at particular risk for PTSD and hence may be at increased risk for chronic pain after surgery. Our goal was to identify risk factors for chronic postoperative pain in young veterans after minor elective surgery, including the contribution of PTSD. METHODS: We reviewed the medical and pharmacy records of veterans (18-50 years old), undergoing elective knee arthroscopy from 2007 to 2010 at the Veteran's Administration Puget Sound Health Care System. The data included demographics, ASA physical status class, comorbidities, anesthesia medications, and opioid prescriptions starting 3.5 months before surgery and ending 3.5 months after surgery. We documented the presence of PTSD based on either the patient's problem list or the clinical notes. We used prolonged postoperative opioid prescription longer than 3 months after surgery as a surrogate for chronic postoperative pain. RESULTS: We identified 145 patients who met inclusion criteria. The median age was 39 ± 8 years old. Eighty-seven percent of the patients were men. The prevalence of PTSD was 32% (95% confidence interval, 25%-41%). PTSD was associated with increased incidence of smoking (P = 0.009) and preoperative opioid use (P = 0.0006). Preoperative opioids were prescribed in 44% (63 of 145) of the patients: in 64% (30 of 47) of patients with PTSD, compared with 34% (33 of 98) in patients without PTSD (P = .0006). Chronic postoperative pain was identified in 30% (43 of 145) of patients. The strongest independent predictor of chronic postoperative pain was an opioid prescription before surgery (odds ratio = 65.3; 95% confidence interval, 014.5-293.0). In patients older than 27.5 years who did not receive opioids before surgery, PTSD may also have been a risk factor for chronic postoperative pain. CONCLUSIONS: This single-center retrospective study suggests that the most important predictor of chronic postoperative pain is preoperative opioid use. For patients not taking opioids preoperatively, PTSD may increase the risk of prolonged postoperative opioid prescriptions and chronic postoperative pain, potentially related to patient age.

Combining Procedural and Behavioral Treatments for Chronic Low Back Pain: A Pilot Feasibility Randomized Controlled Trial.

Individual treatments for chronic low back pain (CLBP) have small magnitude effects. Combining different types of treatments may produce larger effects. This study used a 2×2 factorial randomized controlled trial (RCT) design to combine procedural and behavioral treatments for CLBP. The study aims were to: (1) assess feasibility of conducting a factorial RCT of these treatments; and (2) estimate individual and combined treatment effects of (a) lumbar radiofrequency ablation (LRFA) of the dorsal ramus medial branch nerves (vs. a simulated LRFA control procedure) and (b) Activity Tracker-Informed Video-Enabled Cognitive Behavioral Therapy program for CLBP (AcTIVE-CBT) (vs. an educational control treatment) on back-related disability at 3 months post-randomization. Participants (n=13) were randomized in a 1:1:1:1 ratio. Feasibility goals included an enrollment proportion ≥30%, a randomization proportion ≥80%, and a ≥80% proportion of randomized participants completing the 3-month Roland-Morris Disability Questionnaire (RMDQ) primary outcome endpoint. An intent-to-treat analysis was used. The enrollment proportion was 62%, the randomization proportion was 81%, and all randomized participants completed the primary outcome. Though not statistically significant, there was a beneficial, moderate-magnitude effect of LRFA vs. control on 3-month RMDQ (-3.25 RMDQ points; 95% CI: -10.18, 3.67). There was a significant, beneficial, large-magnitude effect of AcTIVECBT vs. control (-6.29, 95% CI: -10.97, -1.60). Though not statistically significant, there was a beneficial, large effect of LRFA+AcTIVE-CBT vs. control (-8.37; 95% CI: -21.47, 4.74). We conclude that it is feasible to conduct an RCT combining procedural and behavioral treatments for CLBP.

The effect of lung expansion and positive end-expiratory pressure on respiratory mechanics in anesthetized children.

BACKGROUND: Imaging studies have shown that general anesthesia in children results in atelectasis. Lung recruitment total lung capacity (TLC) maneuvers plus positive end-expiratory pressure (PEEP) are effective in preventing atelectasis. However, physiological changes in children during general anesthesia have not been elucidated. METHODS: In eight anesthetized and mechanically ventilated children (median age: 3.5 years; range: 2.3-6.5), we measured static respiratory system elastance (E(st)), flow resistance (R(int)), and elastance and resistance components resulting from tissue viscoelasticity (deltaE and deltaR, respectively) using the constant inflow, end-inspiratory occlusion method preceded by TLC maneuvers, both with zero PEEP (ZEEP) and PEEP (5 cm H2O) for comparison. RESULTS: With constant inspiratory flow V(I) and ZEEP, increases in end-inspiratory lung volume above relaxation volume (tidal volume, V(T)) from 8 to 20 mL x kg(-1) resulted in decreases in E(st) from 1.06 to 0.82 cm H2O x mL(-1) x kg, deltaE from 0.16 to 0.09, and R(int) from 0.13 to 0.11 cm H2O x mL(-1) x s x kg, whereas deltaR increased from 0.08 to 0.12 (P < 0.05). Similar relationships were found with PEEP. Increases in V(I) (8 to 26 mL x s(-1) x kg) with constant V(T) and ZEEP resulted in decreases in E(st) from 1.09 to 0.9 and deltaR from 0.17 to 0.06 (P < 0.01), whereas deltaE and R(int) did not change. There was a similar flow and volume dependence of elastance and resistance with PEEP. CONCLUSIONS: The observed steady decreases in E(st) with increasing V(T) (up to 16 mL/kg with PEEP) indicate marked reductions in end-expiratory relaxation volume (functional residual capacity) even with PEEP. Similarity in results with ZEEP and PEEP suggests that TLC-maneuvers and O2-N2 ventilation prevented airway closure throughout the study.

The relationship between repeated epidural steroid injections and subsequent opioid use and lumbar surgery.

OBJECTIVES: To evaluate whether the use of epidural steroid injections (ESIs) is associated with decreased subsequent opioid use in patients in the Department of Veteran's Affairs (VA) and to determine whether treatment with multiple injections are associated with decreased opioid use and lumbar surgery after ESIs. DESIGN: VA patients undergoing ESIs during the study period for specific low back pain (LBP) diagnoses were identified, and lumbar surgery and opioid use were examined for 6 months before and after ESI. SETTING: National VA administrative data. PARTICIPANTS: U.S. veterans (retrospective data analysis). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Opioid use and lumbar surgery after ESIs. RESULTS: During the 2-year study period, 13,741 different VA patients underwent an ESI for LBP. The majority of patients were using opioids before their ESIs (64%), as were the majority after their ESIs (67%). Of patients not on opioids before the ESIs, 38% were prescribed opioids afterward, whereas only 16% of people on opioids before the ESIs stopped using opioids afterward. Patients who received more than 3 injections were more likely than patients receiving fewer injections to start taking opioids after ESIs (19% vs 13%, P<.001) and to undergo lumbar surgery after ESIs (8.7% vs 6.3%, P=.003). CONCLUSIONS: Opioid use did not decrease in the 6 months after ESIs. In this population, patients who received multiple injections were more likely to start taking opioids and to undergo lumbar surgery within the 6 months after treatment with ESIs. These findings are concerning because our data suggest that ESIs are not reducing opioid use in this VA population.

Injections for chronic pain.

Although interventional procedures should be used cautiously in the setting of chronic pain, there is a role for a variety of injections to facilitate a patient's overall rehabilitation program. There are many resources available, including a prior issue of Physical Medicine and Rehabilitation Clinics of North America, which discuss the more conventional spinal injections. The focus of this article is on lesser-known injection options for treating chronic pain. The authors separately discuss trigger point injections, regenerative injections (prolotherapy), and injections using botulin toxins.

Changes in respiratory system resistance and reactance following acute respiratory and metabolic alkalosis in dogs.

To differentiate between the effects of respiratory and metabolic alkalosis on respiratory mechanics, respiratory system resistance (Rrs) and reactance (Xrs) were examined in anesthetized, paralyzed, and mechanically hyperventilated dogs. Rrs and Xrs were measured by the forced oscillation method with a random noise input of 0-25 Hz. Restoration to normocapnia by CO2 inhalation significantly increased Rrs (+23.4±4.0%), particularly at high-frequency ranges without alterations in Xrs or resonant frequencies, whereas an increase in pH without changes in partial pressure of arterial carbon dioxide (PaCO 2) by an administration of bicarbonate-carbonate mixture resulted in no significant alteration in Rrs or Xrs. A significant decrease in Rrs (-16.3±2.5%) following vagotomy or atropine administration was no longer affected by CO2 inhalation. These results suggest that (1) the vagus nerve appears to play a role in maintaining the resting tension of airway smooth muscle, (2) systemic hypocapnia decreases Rrs presumably due to the central airway dilation, and (3) this response is associated with a change in systemic partial pressure of carbon dioxide (PCO 2) rather than that in pH.

Cervical transforaminal epidural steroid injections: a proposal for optimizing the preprocedural evaluation with available imaging.

Cervical transforaminal epidural steroid injection (CTFESI) has been used to treat cervical radicular pain; however, rare but serious complications such as cerebellar or spinal cord infarction have been reported. The most probable causes of the serious complications include vertebral artery trauma, spasm, or accidental arterial injection of particulate steroid. Several recommendations have been made to improve the safety of CTFESI; however, evaluation and risk assessment of the patient's anatomy by the interventionist have not been sufficiently emphasized. Significant correlations between foraminal narrowing and proximity of the vertebral artery to the target of needle have been reported. This correlation is particularly problematic for interventionists because patients considered or referred for CTFESI are more likely to have foraminal narrowing at the level concerned. Without knowing the patient's anatomy, a common practice of rotating the C-arm obliquely to obtain a full view of the target foramen may carry significant risk of needle's encounter with the vertebral artery. Risk assessment through careful preprocedural review of the patient's magnetic resonance imaging by the interventionist is a worthwhile practice to optimize safety. Special attention should be paid to the vital structures such as the vertebral artery, neural foramen, and carotid artery. A preprocedural roadmap for the safest predicted needle trajectory can be created by simulation using the patient's available magnetic resonance imaging scans. These considerations may guide and help the interventionist to minimize the risk of inadvertent needle placement involving vital structures such as the vertebral artery or carotid artery.

Epidural labor analgesia for a patient with disseminated lymphangiomatosis.

IMPLICATIONS: We describe a case of a parturient with disseminated lymphangiomatosis involving the thorax, retroperitoneum, and lumbar vertebrae who received epidural labor analgesia. Clinical presentations vary depending on the organ systems involved, the extent of the disease, and the stage of pregnancy. Anesthetic implications are discussed.