This Month In: Anesthesiology

Patients undergoing total knee arthroplasty (TKA) may be at risk for inpatient falls. Inpatient falls were identified in 1.6% of the 191,570 records from the national Premier Perspective database of patients undergoing TKA at approximately 400 hospitals between 2006 and 2010. While advanced age, male sex, and individual comorbidities were associated with increased odds of inpatient falls, use of neuraxial anesthesia was associated with lower odds of inpatient falls than general anesthesia alone in a multiple logistic regression model. There was no association between inpatient falls and peripheral nerve block. See the accompanying Editorial View on page 530.

Addition of a femoral nerve block (FNB) to the analgesic regimen for total knee arthroplasty may result in prolonged motor blockade. Ninety-three patients underwent total knee arthroplasty under combined spinal-epidural anesthesia after receiving a randomly assigned adductor canal block (ACB) or FNB. Postoperative analgesia included patient-controlled epidural analgesia. Six to 8 h postanesthetic, ACB was more sparing of quadriceps strength than was FNB while not being inferior to it with respect to pain score and opioid consumption. At 24 and 48 h, there were no differences between groups in these measures. See the accompanying Editorial View on page 530.

Patients may sustain perioperative myocardial injury not diagnosed as myocardial infarction. A diagnosis of myocardial injury after noncardiac surgery (MINS) has been proposed that is defined as prognostically relevant myocardial injury that occurs during or within 30 days after noncardiac surgery. Plasma troponin T concentrations were measured during the first three postoperative days in an international cohort of 15,065 noncardiac surgery patients between 2007 and 2011. MINS was diagnosed in 1,200 patients, 58.2% of whom did not experience an ischemic feature, and was associated with substantial mortality and cardiovascular complications during the first 30 postoperative days. See the accompanying Editorial View on page 533.

Postoperative cognitive dysfunction (POCD) can occur in older adults after total knee arthroplasty (TKA). POCD risk may be indicated by preoperative neuroimaging. Between 2003 and 2005, 40 nondemented TKA patients and 15 matched controls underwent a comprehensive neuropsychological protocol at baseline (before TKA), and 3 weeks, 3 months, and 1 yr postbaseline (after TKA) to determine dominant form(s) of POCD. Thirty-one patients and 12 controls also underwent baseline neuroimaging. Memory and executive declines were primary forms of POCD at 3 weeks. Preoperative neuroimaging evidence of microvascular disease explained part of executive function decline at 3-week and 1-yr postoperative sessions.

Wound healing depends on the microcirculation that supplies the incision area. The age-related reduction in the microcirculation affects wound healing and the incidence of surgical site infection. The effect of aging on wound repair is reviewed as are the potential benefits of various aspects of perioperative management that may support the microcirculation and improve wound repair. The latter include maintenance of normal body temperature and control of postoperative pain as well as choice of anesthetic technique and use of opioids, judicious fluid management, and increased tissue oxygen tension.

Including a peripheral nerve block as part of the anesthetic plan for ambulatory surgery may prove beneficial. Sixty-four women scheduled for elective unilateral breast tumor resection were randomly assigned to have propofol-based total intravenous anesthesia with ultrasound-guided thoracic paravertebral blocks or sevoflurane-based general anesthesia with opioid analgesia and sham local anesthetics injections. Total intravenous anesthesia with paravertebral blocks was reliable and resulted in a better quality of recovery on hospital discharge and the second postoperative day than did inhalational anesthesia with opioid analgesia. Pain scores were also reduced through postoperative day 2 in the paravertebral block group.

Mastocytosis is a group of disorders characterized by an increase in mast cells that can be limited to skin or infiltrate bone marrow and other organs. The main anesthetic concern in patients with mastocytosis is avoiding psychological, pharmacological, mechanical, and temperature changes that can elicit immediate nonallergic hypersensitivity reactions that occur after mast cell degranulation. Perioperative mast cell degranulation, perioperative management of patients with mastocytosis, management of perioperative mast cell degranulation, etiological diagnosis of mastocytosis, and what should be done in patients with mastocytosis before anesthesia and surgery are reviewed.

Acute lung injury after smoke inhalation is characterized by an inflammatory process, which is manifested clinically 2 to 3 days after inhalation. Unilateral injury was induced in five sheep by delivering 48 breaths of cotton smoke to the left lung while the contralateral lung served as control. Pulmonary inflammatory cell metabolic activity, measured by positron emission tomography (PET) as [18F]fluorodeoxyglucose net uptake rate, was increased by 4 h after injury and the perfusion-weighted ventilation–perfusion distribution, measured with [13N]nitrogen in saline by PET, was more heterogeneous and shifted toward units with lower ventilation-to-perfusion ratios in the smoke-exposed lung.