Xavier Capdevila

BACKGROUND: Continuous passive motion after major knee surgery optimizes the functional prognosis but causes severe pain. The authors tested the hypothesis that postoperative analgesic techniques influence surgical outcome and the duration of convalescence. METHODS: Before standardized general anesthesia, 56 adult scheduled for major knee surgery were randomly assigned to one of three groups, each to receive a different postoperative analgesic technique for 72 h: continuous epidural infusion, continuous femoral block, or intravenous patient-controlled morphine (dose, 1 mg; lockout interval, 7 min; maximum dose, 30 mg/4 h). The first two techniques were performed using a solution of 1% lidocaine, 0.03 mg/ml morphine, and 2 microg/ml clonidine administered at 0.1 ml x kg(-1) x h(-1). Pain was assessed at rest and during continuous passive motion using a visual analog scale. The early postoperative maximal amplitude of knee flexion was measured during continuous passive motion at 24 h and 48 h and compared with the target levels prescribed by the surgeon. To evaluate functional outcome, the maximal amplitudes were measured again on postoperative day 5, at hospital discharge (day 7), and at 1- and 3-month follow-up examinations. When the patients left the surgical ward, they were admitted to a rehabilitation center, where their length of stay depended on prospectively determined discharge criteria RESULTS: The continuous epidural infusion and continuous femoral block groups showed significantly lower visual analog scale scores at rest and during continuous passive motion compared with the patient-controlled morphine group. The early postoperative knee mobilization levels in both continuous epidural infusion and continuous femoral block groups were significantly closer to the target levels prescribed by the surgeon than in the patient-controlled morphine group. On postoperative day 7, these values were 90 degrees (60-100 degrees)(median and 25th-75th percentiles) in the continuous epidural infusion group, 90 degrees (60-100 degrees) in the continuous femoral block group, and 80 degrees (60-100 degrees) in the patient-controlled morphine group (P < 0.05). The durations of stay in the rehabilitation center were significantly shorter: 37 days (range, 30-45 days) in the continuous epidural infusion group, 40 days (range, 31-60 days) in the continuous femoral block group, and 50 days (range, 30-80 days) in the patient-controlled morphine group (P < 0.05). Side effects were encountered more frequently in the continuous epidural infusion group. CONCLUSION: Regional analgesic techniques improve early rehabilitation after major knee surgery by effectively controlling pain during continuous passive motion, thereby hastening convalescence.

RATIONALE: Diaphragmatic function is a major determinant of the ability to successfully wean patients from mechanical ventilation (MV). Paradoxically, MV itself results in a rapid loss of diaphragmatic strength in animals. However, very little is known about the time course or mechanistic basis for such a phenomenon in humans. OBJECTIVES: To determine in a prospective fashion the time course for development of diaphragmatic weakness during MV; and the relationship between MV duration and diaphragmatic injury or atrophy, and the status of candidate cellular pathways implicated in these phenomena. METHODS: Airway occlusion pressure (TwPtr) generated by the diaphragm during phrenic nerve stimulation was measured in short-term (0.5 h; n = 6) and long-term (>5 d; n = 6) MV groups. Diaphragmatic biopsies obtained during thoracic surgery (MV for 2-3 h; n = 10) and from brain-dead organ donors (MV for 24-249 h; n = 15) were analyzed for ultrastructural injury, atrophy, and expression of proteolysis-related proteins (ubiquitin, nuclear factor-κB, and calpains). MEASUREMENTS AND MAIN RESULTS: TwPtr decreased progressively during MV, with a mean reduction of 32 ± 6% after 6 days. Longer periods of MV were associated with significantly greater ultrastructural fiber injury (26.2 ± 4.8 vs. 4.7 ± 0.6% area), decreased cross-sectional area of muscle fibers (1,904 ± 220 vs. 3,100 ± 329 μm²), an increase of ubiquitinated proteins (+19%), higher expression of p65 nuclear factor-κB (+77%), and greater levels of the calcium-activated proteases calpain-1, -2, and -3 (+104%, +432%, and +266%, respectively) in the diaphragm. CONCLUSIONS: Diaphragmatic weakness, injury, and atrophy occur rapidly in critically ill patients during MV, and are significantly correlated with the duration of ventilator support.

OBJECTIVES: To describe the current practice of physicians, to report complications associated with endotracheal intubation (ETI) performed in THE intensive care unit (ICU), and to isolate predictive factors of immediate life-threatening complications. DESIGN: Multiple-center observational study. SETTING: Seven intensive care units of two university hospitals. PATIENTS: : We evaluated 253 occurrences of ETI in 220 patients. INTERVENTIONS: From January 1 to June 30, 2003, data related to all ETI performed in ICU were collected. Information regarding patient descriptors, procedures, and immediate complications were analyzed. MEASUREMENTS AND MAIN RESULTS: The main indications to intubate the trachea were acute respiratory failure, shock, and coma. Some 148 ETIs (59%) were performed by residents. At least one severe complication occurred in 71 ETIs (28%): severe hypoxemia (26%), hemodynamic collapse (25%), and cardiac arrest (2%). The other complications were difficult intubation (12%), cardiac arrhythmia (10%), esophageal intubation (5%), and aspiration (2%). Presence of acute respiratory failure and the presence of shock as an indication for ETI were identified as independent risk factors for occurrence of complications, and ETI performed by a junior physician supervised by a senior (i.e., two operators) was identified as a protective factor for the occurrence of complications. CONCLUSIONS: ETI in ICU patients is associated with a high rate of immediate and severe life-threatening complications. Independent risk factors of complication occurrence were presence of acute respiratory failure and presence of shock as an indication for ETI. Further studies should aim to better define protocols for intubation in critically ill patients to make this procedure safer.

BACKGROUND: Continuous peripheral nerve block (CPNB) is the technique of choice for postoperative analgesia after painful orthopedic surgery. However, the incidence of neurologic and infectious adverse events in the postoperative period are not well established. This issue was the aim of the study. METHODS: Patients scheduled to undergo orthopedic surgery performed with a CPNB were prospectively included during 1 yr in a multicenter study. Efficacy of postoperative analgesia, bacteriologic cultures of the catheter, and acute neurologic and infectious adverse events were evaluated after surgery in 1,416 patients at arrival in the postanesthesia care unit, at hour 1, and every 24 h up to day 5. Risk factors for adverse events were determined using logistic regression. RESULTS: The median duration of CPNB was 56 h. Both general anesthesia and CPNB were performed in 73.6% of the patients. Postoperative analgesia was effective in 96.3%, but an increase in pain scores was noted at hour 24 (P = 0.01). Hypoesthesia or numbness occurred in 3% and 2.2%, respectively, and paresthesia occurred in 1.5%. Three neural lesions (0.21%) were noted after continuous femoral nerve block. Two of these patients were anesthetized during block procedure. Nerve damage completely resolved 36 h to 10 weeks later. Cultures from 28.7% of the catheters were positive. Three percent of patients had local inflammatory signs. The bacterial species most frequently found were coagulase-negative staphylococcus (61%) and gram-negative bacillus (21.6%). A Staphylococcus aureus psoas abscess (0.07%) was reported in one diabetic woman. Independent risk factors for paresthesia/dysesthesia were postoperative monitoring in intensive care, age less than 40 yr, and use of bupivacaine. Risk factors for local inflammation/infection were postoperative monitoring in intensive care, catheter duration greater than 48 h, male sex, and absence of antibiotic prophylaxis. CONCLUSION: CPNB is an effective technique for postoperative analgesia. Minor incidents and bacterial colonization of catheters are frequent, with no adverse clinical consequences in the large majority of cases. Major neurologic and infectious adverse events are rare.

The development of chronic pain is considered a major complication after surgery. Basic science research in animal models helps us understand the transition from acute to chronic pain by identifying the numerous molecular and cellular changes that occur in the peripheral and central nervous systems. It is now well recognized that inflammation and nerve injury lead to long-term synaptic plasticity that amplifies and also maintains pain signaling, a phenomenon referred to as pain sensitization. In the context of surgery in humans, pain sensitization is both responsible for an increase in postoperative pain via the expression of wound hyperalgesia and considered a critical factor for the development of persistent postsurgical pain. Using specific drugs that block the processes of pain sensitization reduces postoperative pain and prevents the development of persistent postoperative pain. This narrative review of the literature describes clinical investigations evaluating different preventative pharmacologic strategies that are routinely used by anesthesiologists in their daily clinical practices for preventing persistent postoperative pain. Nevertheless, further efforts are needed in both basic and clinical science research to identify preclinical models and novel therapeutics targets. There remains a need for more patient numbers in clinical research, for more reliable data, and for the development of the safest and the most effective strategies to limit the incidence of persistent postoperative pain.