Postoperative delirium after major orthopedic surgery.

BACKGROUND: Postoperative delirium (POD) is one of the most common complications in older adult patients undergoing elective surgery. Few studies have compared, within the same institution, the type of surgery, risk factors and type of anesthesia and analgesia associated with the development of POD. AIM: To investigate the following three questions: (1) What is the incidence of POD after non-ambulatory orthopedic surgery at a high-volume orthopedic specialty hospital? (2) Does surgical procedure influence incidence of POD after non-ambulatory orthopedic surgery? And (3) For POD after non-ambulatory orthopedic surgery, what are modifiable risk factors? METHODS: A retrospective cohort study was conducted of all non-ambulatory orthopedic surgeries at a single orthopedic specialty hospital between 2009 and 2014. Patients under 18 years were excluded from the cohort. Patient characteristics and medical history were obtained from electronic medical records. Patients with POD were identified using International Classification of Diseases, 9th Revision (ICD-9) codes that were not present on admission. For incidence analyses, the cohort was grouped into total hip arthroplasty (THA), bilateral THA, total knee arthroplasty (TKA), bilateral TKA, spine fusion, other spine procedures, femur/pelvic fracture, and other procedures using ICD-9 codes. For descriptive and regression analyses, the cohort was grouped, using ICD-9 codes, into THA, TKA, spinal fusions, and all procedures. RESULTS: Of 78492 surgical inpatient surgeries, the incidence from 2009 to 2014 was 1.2% with 959 diagnosed with POD. The incidence of POD was higher in patients undergoing spinal fusions (3.3%) than for patients undergoing THA (0.8%); THA patients had the lowest incidence. Also, urgent and/or emergent procedures, defined by femoral and pelvic fractures, had the highest incidence of POD (7.2%) than all other procedures. General anesthesia was not seen as a significant risk factor for POD for any procedure type; however, IV patient-controlled analgesia was a significant risk factor for patients undergoing THA [Odds ratio (OR) = 1.98, 95% confidence interval (CI): 1.19 to 3.28, P = 0.008]. Significant risk factors for POD included advanced age (for THA, OR = 4.9, 95%CI: 3.0-7.9, P < 0.001; for TKA, OR = 2.16, 95%CI: 1.58-2.94, P < 0.001), American Society of Anesthesiologists score of 3 or higher (for THA, OR = 2.01, 95%CI: 1.33-3.05, P < 0.001), multiple medical comorbidities, hyponatremia (for THA, OR = 2.36, 95%CI: 1.54 to 3.64, P < 0.001), parenteral diazepam (for THA, OR = 5.05, 95%CI: 1.5-16.97, P = 0.009; for TKA, OR = 4.40, 95%CI: 1.52-12.75, P = 0.007; for spine fusion, OR = 2.17, 95%CI: 1.19-3.97, P = 0.01), chronic opioid dependence (for THA, OR = 7.11, 95%CI: 3.26-15.51, P < 0.001; for TKA, OR = 2.98, 95%CI: 1.38-6.41, P = 0.005) and alcohol dependence (for THA, OR = 5.05, 95%CI: 2.72-9.37, P < 0.001; for TKA, OR = 6.40, 95%CI: 4.00-10.26, P < 0.001; for spine fusion, OR = 6.64, 95%CI: 3.72-11.85, P < 0.001). CONCLUSION: POD is lower (1.2%) than previously reported; likely due to the use of multi-modal regional anesthesia and early ambulation. Both fixed and modifiable factors are identified.

Pregabalin Did Not Improve Pain Management After Spinal Fusions.

BACKGROUND: The treatment of postoperative pain is a challenge after posterior spinal fusions. Pain management using predominantly opioids is often associated with multiple adverse effects, while multimodal postoperative analgesia may provide adequate pain relief with fewer opioid side effects. QUESTIONS/PURPOSES: The purpose of this review is to determine whether addition of 150 mg pregabalin daily would reduce narcotic requirements and improve outcomes after posterior lumbar fusion (PLF). METHODS: The method used is a randomized, controlled trial of elective PLF patients who received pregabalin or placebo. With institutional review board (IRB) approval, 86 patients undergoing elective posterior lumbar fusion, ASA I-III, were randomized to receive either a placebo or pregabalin after obtaining written informed consent. Both arms, i.e., placebo and pregabalin, consisted of 43 patients each.The 86 patients for elective PLF were randomly assigned to receive 150 mg of pregabalin 1 h before surgery and then 150 mg daily, or a placebo tablet. All patients received a similar general anesthetic and in the post-anesthesia care unit (PACU), started on intravenous (IV) patient-controlled analgesia (PCA) of hydromorphone (0.2 mg/ml). Postoperative pain was assessed daily until discharge using a Numerical Rating Scale (NRS) at rest and with physical therapy (PT). Patients were also assessed twice daily for level of sedation and nausea and/or vomiting and expected PT milestones. All narcotics (IV, oral) were documented. RESULTS: Demographics and operative time between groups were similar. PCA hydromorphone administration and oral narcotic intake were not statistically different between the two groups. However, an increased incidence of nausea and vomiting in the placebo group reached statistical significance (p < 0.05). In addition, there was no statistical difference between groups with respect to achieving PT milestones and hospital discharge day. CONCLUSION: After PLF, patients receiving pregabalin 150 mg/day did not have reduced IV narcotic usage, improved PT milestones, or reduced length of hospital stay. We were unable to demonstrate an analgesic advantage to prescribing pregabalin to patients undergoing lumbar spinal fusions.

The Incidence of Perioperative Cardiac Events after Orthopedic Surgery: A Single Institutional Experience of Cases Performed over One Year.

BACKGROUND: Orthopedic patients with ischemic heart disease are at risk for postoperative cardiac complications. QUESTIONS/PURPOSES: Using information from two medical information retrieval systems which insured the capture of all events for the period of study, our goals were to determine the incidence of myocardial injury in at-risk patients after orthopedic surgery and to delineate the type and incidence of cardiac complications in this population. METHODS: For one year, at an orthopedic hospital, we identified all postoperative patients with a measured cTnI level using an electronic ordering system. Preoperative cardiac risk factors and postoperative cardiac complications were identified in patients undergoing a total hip arthroplasty (THA), total knee arthroplasty (TKA), and posterior spinal fusion (PSF). A postoperative myocardial infarction was defined by a cTnI > 0.1 ng/mL, ECG changes, new echocardiographic regional wall motion abnormalities, and evaluation by a cardiologist. Categorical variables were compared among groups with a Fisher's exact or Chi-square test. Continuous variables were compared among groups with ANOVA or the Kruskal-Wallis test. The associations of cardiac risk factors with myocardial injury are expressed as odds ratios from logistic regression models. RESULTS: During a one-year period, from 10,627 inpatient orthopedic procedures, 805 patients were identified as at risk for postoperative myocardial ischemia. A total of 20.6% (166/805) of these patients had elevated serum cTnI levels (cTnI > 0.02 ng/mL), and there were ten documented postoperative MIs (10/805; 1.2%). For the at-risk TKA, THA, or PSF patients, 19% (102/532) had elevated cTnI levels and 31% (32/102) had postoperative cardiac complications, including arrhythmias (56%), congestive heart failure (2%), and MI (1%). Adjusting for sex, age, BMI, cardiac risk factors, and medications (statins and ß-blockers), PSF patients had 3.9 times the risk of myocardial injury (p = 0.003) compared to TKA patients and 4.2 times that of THA patients. CONCLUSIONS: The incidence of postoperative myocardial ischemia after major orthopedic surgery in patients with cardiac risk factors is high (8.7%), but the incidence of documented myocardial infarctions and serious cardiac complications remains low (1.2-2%). Patients with higher postoperative cTnI releases were more likely to have cardiac complications, and some procedures (spinal fusions) placed the patients at a higher risk.

A randomized crossover study of the effects of lidocaine on motor- and sensory-evoked potentials during spinal surgery.

BACKGROUND CONTEXT: Lidocaine has emerged as a useful adjuvant anesthetic agent for cases requiring intraoperative monitoring of motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SSEPs). A previous retrospective study suggested that lidocaine could be used as a component of propofol-based intravenous anesthesia without adversely affecting MEP or SSEP monitoring, but did not address the effect of the addition of lidocaine on the MEP and SSEP signals of individual patients. PURPOSE: The purpose of this study was to examine the intrapatient effects of the addition of lidocaine to balanced anesthesia on MEPs and SSEPs during multilevel posterior spinal fusion. STUDY DESIGN: This is a prospective, two-treatment, two-period crossover randomized controlled trial with a blinded primary outcome assessment. PATIENT SAMPLE: Forty patients undergoing multilevel posterior spinal fusion were studied. OUTCOME MEASURES: The primary outcome measures were MEP voltage thresholds and SSEP amplitudes. Secondary outcome measures included isoflurane concentrations and hemodynamic parameters. METHODS: Each participant received two anesthetic treatments (propofol 50 mcg/kg/h and propofol 25 mcg/kg/h+lidocaine 1 mg/kg/h) along with isoflurane, ketamine, and diazepam. In this manner, each patient served as his or her own control. The order of administration of the two treatments was determined randomly. RESULTS: There were no significant within-patient differences between MEP threshold voltages or SSEP amplitudes during the two anesthetic treatments. CONCLUSIONS: Lidocaine may be used as a component of balanced anesthesia during multilevel spinal fusions without adversely affecting the monitoring of SSEPs or MEPs in individual patients.

The Need for a Step-up in Postoperative Medical Care is Predictable in Orthopedic Patients Undergoing Elective Surgery.

BACKGROUND: The goal of elective orthopedic surgery is to return patients to their expected level of activity without an increased incidence of postoperative complications. The first step is identifying patient and/or surgical characteristics responsible for these complications. QUESTIONS/PURPOSES: This study sought to identify predictors of a step-up in medical care after non-ambulatory elective orthopedic surgery. METHODS: At a single specialty orthopedic hospital, we identified all in-hospital postoperative patients who were transferred to a higher level of medical care ((PACU) post-anesthesia care unit). The characteristics of both transferred and non-transferred patients were compared. A model was built which incorporated predictors of return to a higher level of care. RESULTS: During a 1-year period, 155 of 7967 patients (1.95%) required transfer to the PACU within 5 days of surgery. Cardiac complications were the major reason for transfer (50.3%), followed by pulmonary (11.0%) and neurological complications (9.7%). Patients who returned to the PACU were older, had more Exlihauser comorbidities, and had obstructive sleep apnea (OSA). In a model adjusting for all patient characteristics: age, American Society of Anesthesiologists (ASA) status, congestive heart failure (CHF), the Charlson comorbidity index and OSA predicted return to the PACU. CONCLUSIONS: In an elderly population with multiple comorbidities undergoing elective common major orthopedic procedures, approximately 2% of patients required readmission to the PACU. The most common problems requiring this step-up in care were cardiac and pulmonary, which resulted in an increased length of hospital stay. Patients with OSA and multiple comorbidities undergoing total knee arthroplasty carry an increased risk for postoperative complications.

Prothrombin Time and Activated Partial Thromboplastin Time Testing: A Comparative Effectiveness Study in a Million-Patient Sample.

BACKGROUND: A substantial fraction of all American healthcare expenditures are potentially wasted, and practices that are not evidence-based could contribute to such waste. We sought to characterize whether Prothrombin Time (PT) and activated Partial Thromboplastin Time (aPTT) tests of preoperative patients are used in a way unsupported by evidence and potentially wasteful. METHODS AND FINDINGS: We evaluated prospectively-collected patient data from 19 major teaching hospitals and 8 hospital-affiliated surgical centers in 7 states (Delaware, Florida, Maryland, Massachusetts, New Jersey, New York, Pennsylvania) and the District of Columbia. A total of 1,053,472 consecutive patients represented every patient admitted for elective surgery from 2009 to 2012 at all 27 settings. A subset of 682,049 patients (64.7%) had one or both tests done and history and physical (H&P) records available for analysis. Unnecessary tests for bleeding risk were defined as: PT tests done on patients with no history of abnormal bleeding, warfarin therapy, vitamin K-dependent clotting factor deficiency, or liver disease; or aPTT tests done on patients with no history of heparin treatment, hemophilia, lupus anticoagulant antibodies, or von Willebrand disease. We assessed the proportion of patients who received PT or aPTT tests who lacked evidence-based reasons for testing. CONCLUSIONS: This study sought to bring the availability of big data together with applied comparative effectiveness research. Among preoperative patients, 26.2% received PT tests, and 94.3% of tests were unnecessary, given the absence of findings on H&P. Similarly, 23.3% of preoperative patients received aPTT tests, of which 99.9% were unnecessary. Among patients with no H&P findings suggestive of bleeding risk, 6.6% of PT tests and 7.1% of aPTT tests were either a false positive or a true positive (i.e. indicative of a previously-undiagnosed potential bleeding risk). Both PT and aPTT, designed as diagnostic tests, are apparently used as screening tests. Use of unnecessary screening tests raises concerns for the costs of such testing and the consequences of false positive results.

Blood Transfusions May Have Limited Effect on Muscle Oxygenation After Total Knee Arthroplasty.

BACKGROUND: Traditionally, blood transfusions in the perioperative setting are used to maintain adequate delivery of nutrients and oxygen to organs. However, the effect of blood administration on tissue oxygenation in the perioperative setting remains poorly understood. QUESTIONS/PURPOSES: The aim of this study was to determine changes in muscle tissue oxygenation saturation (SmO2) in response to perioperative blood transfusions. PATIENTS AND METHODS: Patients undergoing total knee arthroplasty were enrolled. SmO2, continuous hemoglobin (SpHb), stroke volume (SV), cardiac index, and standard hemodynamic parameters including heart rate (HR), mean arterial blood pressure (MAP), and arterial oxygen saturation (SO2) were recorded. To assess fluid responsiveness, a passive leg raise (PLR) test was performed before the transfusions were started. RESULTS: Twenty-eight patients were included in the analysis. Mean (±SD) SmO2 before transfusion was 63.18 ± 10.04%, SpHb was 9.27 ± 1.16 g/dl, and cardiac index was 2.62 ± 0.75 L/min/m(2). A significant increase during the course of blood transfusion was found for SmO2 (+3.44 ± 5.81% [95% confidence interval (CI) 1.04 to 5.84], p = 0.007), SpHb (0.74 ± 0.92 g/dl [95% CI 0.35 to 1.12], p < 0.001), and cardiac index (0.38 ± 0.51 L/min/m2 [95% CI 0.15 to 0.60], p = 0.002), respectively. However, the correlation between SmO2 and SpHb over the course of the transfusion was negligible (ρ = 0.25 [95% CI -0.03 to 0.48]). A similar lack of correlation was found when analyzing data of those patients who showed a positive leg raise test before the start of the transfusion (ρ = 0.37 [95% CI -0.11 to 0.84]). CONCLUSION: We detected a statistically significant increase in SmO2 during the course of a single unit blood transfusion compared to baseline. However, there was no evidence of a correlation between longitudinal SmO2 and SpHb measurements.

Clinical outcomes in patients with pulmonary hypertension undergoing total hip arthroplasty.

BACKGROUND: Pulmonary hypertension (PH) is regarded as a risk factor for perioperative complications in patients undergoing noncardiac surgery. QUESTIONS/PURPOSES: The objective of this retrospective case-control study was to evaluate the adverse outcomes of pulmonary hypertension patients undergoing elective unilateral hip replacements. METHODS: We performed a retrospective case-control study of total hip replacement patients with pulmonary hypertension (cases) and without pulmonary hypertension (control). From the years 2003 to 2008, we identified a total of 132 patients undergoing primary total hip replacements with a diagnosis of pulmonary hypertension (right ventricular systolic pressure >35). The primary outcome assessed was the incidence of adverse events that occurred during the postoperative hospital stay. Secondary outcomes studied included length of hospital stay, mortality, and ability to reach certain physical therapy milestones. RESULTS: The PH group had significantly more adverse events than the control group. Nonlethal cardiac dysrhythmias comprised the most common adverse outcome among the PH group. Overall, the PH group had a morbidity rate of 34.7% while the control had a rate of 21%. The PH group had longer hospital stay (6.7 days vs. 5.9). Both groups had zero mortality during the hospital stay. The PH group had comparable rehabilitation recovery times than the control group. CONCLUSION: This retrospective case-control study demonstrates that pulmonary hypertension patients undergoing total hip arthroplasty are more prone to adverse outcomes, especially cardiac dysrhythmias, and longer hospital stays.

Steroid modulation of cytokine release and desmosine levels in bilateral total knee replacement: a prospective, double-blind, randomized controlled trial.

BACKGROUND: The perioperative inflammatory response as measured by elevated levels of interleukin-6 (IL-6) has been linked to acute respiratory distress syndrome, postoperative confusion, and fever. Because of the extent of surgery,patients undergoing bilateral total knee arthroplasty may be at high risk of complications. We had found a significant decrease in IL-6 in patients having bilateral total knee replacement who received two doses of 100 mg of hydrocortisone eight hours apart; however, by twenty-four hours, IL-6 levels were equal to those in the group that received a placebo. In the present study, we investigated whether the administration of three doses would reduce IL-6 levels at twenty-four hours and affect other outcomes such as desmosine level, a marker of lung injury. METHODS: After institutional review board approval, a total of thirty-four patients (seventeen patients and seventeen control subjects) were enrolled in this double-blind, randomized, placebo-controlled study. Three doses of intravenous hydrocortisone (100 mg) or placebo were given eight hours apart. Urinary desmosine levels were obtained at baseline and at one and three days postoperatively. The level of IL-6 was measured at baseline and at six, ten, twenty-four, and forty-eight hours postoperatively. Pain scores, presence of fever, and functional outcomes were recorded. RESULTS: The level of IL-6 increased in both groups, but was significantly higher in the control group, peaking at twenty-four hours (mean and standard deviation, 623.74 ± 610.35 pg/mL versus 148.13 ± 119.35 pg/mL; p = 0.006). Urinary desmosine levels significantly increased by twenty-four hours in the control group, but remained unchanged in the study group (134.75 ± 67.88 pmol/mg and 79.45 ± 46.30 pmol/mg, respectively; p = 0.006). Pain scores at twenty-four hours were significantly lower in the study group (1.4 ± 0.9 versus 2.4 ± 1.2; p = 0.01) as was the presence of fever (11.8%versus 47.1%; p = 0.03). Range of motion at the knee was significantly greater in the study group (81.6 ± 11.6 versus 70.6 ± 14.0 in the right knee [p = 0.02] and 81.4 ± 11.3 versus 73.4 ± 9.4 in the left knee [p = 0.03]). CONCLUSIONS: Hydrocortisone (100 mg) given over three doses, each eight hours apart, decreased and maintained a lower degree of inflammation with bilateral total knee replacement as measured by IL-6 level. Corticosteroids decreased the prevalence of fever, lowered visual analog pain scores, and improved knee motion. The significantly lower values of desmosine in the study group suggest that this treatment may be protective against lung injury.

Use of low-dose steroids in decreasing cytokine release during bilateral total knee replacement.

BACKGROUND: Interleukin 6 (IL-6), a marker of inflammation, is one of the major cytokines released during joint replacement. In the orthopedic patient population, high levels have been linked to many adverse effects including acute respiratory distress syndrome, postoperative mental status changes, and fever. We looked to assess the efficacy of low-dose steroids on the postinflammatory response as measured by IL-6 in patients undergoing bilateral total knee replacement (BTKR). The role of steroids has never been evaluated before in that setting. METHODS: Double-blind, randomized, placebo-controlled study of 30 patients undergoing BTKR. The study was powered in order to detect at least a 25% decrease in IL-6 from control. Hydrocortisone (100 mg) or placebo was given at 2 doses 8 hrs apart to the study and control group respectively. Clinical outcome was assessed as well. RESULTS: Levels of IL-6 were 40% lower in the study group by 10 hrs (P = 0.0037) but were similar to the control group at 24 hrs. Greater hemodynamic stability was noted in the study group with fewer episodes of hypotension postoperatively (P = 0.031). Range of motion gained on discharge was also greatest in the study group (P = 0.049). Absence of infection and normal wound healing were noted in all patients. CONCLUSIONS: The use of hydrocortisone significantly decreased the inflammatory response in patients undergoing BTKR as measured by IL-6 production. Further studies looking at clinical implications of such findings in a larger patient population and with a longer course of steroids are warranted.

The utility of urine desmosine as a marker of lung injury in spine surgery.

The objective of this prospective observational study was to determine if urine desmosine levels, a marker of lung injury, increase in response to the periopreative insults of anterior and posterior spine surgery. Desmosine, a stable breakdown product of elastin, has been proposed as a surrogate marker of lung injury in patients with COPD, tobacco use, and ARDS. We recently evaluated this marker in patients undergoing knee surgery, but the utility of desmosine as a marker of lung injury in patients undergoing spine surgery remains unstudied. In this study, we enrolled ten consecutive patients, who underwent anterior/posterior spine surgery. Patient demographics and perioperative data were recorded. Urine samples were collected at baseline, 1 day, and 3 days postoperatively and analyzed for levels of desmosine using a previously validated radioimmunoassay. Desmosine levels were 35.9 ± 18.2 pmol/mg creatinine at baseline, 38.7 ± 11 pmol/mg creatinine on postoperative day 1, and 70.5 ± 49.1 pmol/mg creatinine on postoperative day 3, respectively. Desmosine/creatinine ratios measured on day 3 postoperatively were significantly elevated compared to levels at baseline, and represented a 96.3% increase. No difference was seen between levels at baseline and day 1 postoperatively. In conclusion, we were able to show a significant increase in urine desmosine levels associated with anterior/posterior spine surgery. In the context of previous studies, our findings suggest that desmosine may be a marker of lung injury in this setting. However, further research is warranted for validation and correlation of desmosine levels to clinical markers and various degrees of lung injury.

Comparison of the transarterial axillary block and the ultrasound-guided infraclavicular block for upper extremity surgery: a prospective randomized trial.

BACKGROUND AND OBJECTIVES: The transarterial axillary block and the ultrasound-guided infraclavicular block are both effective methods of anesthetizing the upper extremity. This study compares these methods with respect to subjective postoperative dysesthesias, block adequacy, patient comfort, and patient satisfaction. METHODS: Two hundred thirty-two patients were randomized to receive an ultrasound-guided infraclavicular block or a transarterial axillary block for upper extremity surgery. Block placement, motor and sensory testing, and block adequacy data were recorded. The subjects were contacted by a blinded research assistant at 2 and 10 days postoperatively to assess for the presence of dysesthesias and pain and to assess patient satisfaction. RESULTS: The 2 techniques were similar with respect to block performance time and adequacy of the block for surgery. There was no significant difference between the blocks in terms of postoperative dysesthesias (23.9% in the axillary group vs 17.1% in the infraclavicular group at 2 days, P = 0.216, and 11.0% vs 6.31% at 10 days, P = 0.214). None of the dysesthesias were permanent. The infraclavicular block had a lower incidence of paresthesias during placement (P = 0.035) and was associated with less pain at the block site (P = 0.010 at 2 days, P = 0.002 at 10 days). More patients were willing to undergo the infraclavicular block as a future anesthetic when compared with the axillary block (P = 0.025 at 10 days). CONCLUSIONS: There is no significant difference between the 2 techniques in terms of adequacy for surgery and subjective postoperative dysesthesias. The ultrasound-guided infraclavicular block is associated with greater patient comfort and willingness to undergo the same anesthetic when compared with the transarterial axillary block.

Pulmonary artery versus central venous catheter monitoring in the outcome of patients undergoing bilateral total knee replacement.

Bilateral total knee replacement (BTKR) has been associated with a higher incidence of fat embolism (FES) compared to single knee replacement. Consequently, intraoperative monitoring with a pulmonary artery catheter (PAC) has been recommended. This study compares clinical outcome in BTKR patients monitored with central venous pressure versus PAC. A retrospective chart review of 249 consecutive patients undergoing BTKR, 132 of whom had PAC insertion versus 117 who had central line insertion, over a 1-year period were included in the study. Their medical records were reviewed for co-morbidities, baseline characteristics, and type of intraoperative monitoring. Need and duration for postoperative monitoring in the postoperative care, length of hospital stay (LOHS), signs of fat embolism, development of arrhythmias, and respiratory failure were all outcome measures. A total of four patients (1.6%) had FES as per Schonfeld criteria. One of these patients died within 48 h of surgery. They all had PAC monitoring intraoperatively. Pulmonary artery pressure (PAP) remained unchanged during surgery which raises doubt as to the clinical utility and advisability of the use of PAC's in this setting. There was no statistically significant difference in cardiac or pulmonary complications, or LOHS between the two groups. Central venous pressure monitoring appears to be sufficient in patients undergoing BTKR.

Correlation between centrally versus peripherally transduced venous pressure in prone patients undergoing posterior spine surgery.

STUDY DESIGN: Prospective clinical observational study. OBJECTIVE: To evaluate the correlation and agreement between peripherally and centrally transduced venous pressures in prone spine surgery patients. SUMMARY OF BACKGROUND DATA: In view of a variety of potential complications associated with the placement of central venous lines for the purpose of central venous pressure (CVP) monitoring, a number of authors have suggested that the use of peripherally transduced pressures (PVP) instead may yield similar results. Data confirming the validity of this technique for the purpose of intravascular fluid volume monitoring in prone patients undergoing spine surgery remain scarce. METHODS: After protocol approval by the internal review board, we enrolled 40 patients who underwent spine surgery in the prone position. CVP and PVP were recorded simultaneously. The data pairs were analyzed for correlation. Bland and Altman plots were created to evaluate the degree of agreement between the 2 modes of venous pressure monitoring. RESULTS: A total of 1275 data pairs were collected. The mean PVP was 17.55 mm Hg +/- 4.93 mm Hg and the mean CVP 15.52 mm Hg +/- 4.77 mm Hg (P < 0.001), thus yielding a mean difference of 2.04 mm Hg +/- 1.39 mm Hg. PVP and CVP correlated well over a wide range of pressures (r = 0.949, r = 0.920 [P < 0.001]). A high level of agreement was found between both methods of venous pressure measurement. CONCLUSION: CVP and PVP correlate well under conditions associated with prone spine surgery. With a high level of agreement found in this study, PVP may represent an attractive alternative to CVP monitoring to assess fluid volume trends intraoperatively.

Ketamine as an adjunct to postoperative pain management in opioid tolerant patients after spinal fusions: a prospective randomized trial.

Management of acute postoperative pain is challenging, particularly in patients with preexisting narcotic dependency. Ketamine has been used at subanesthetic doses as a N-methyl D-aspartate (NMDA) receptor antagonist to block the processing of nociceptive input in chronic pain syndromes. This prospective randomized study was designed to assess the use of ketamine as an adjunct to acute pain management in narcotic tolerant patients after spinal fusions. Twenty-six patients for 1-2 level posterior lumbar fusions with segmental instrumentation were randomly assigned to receive ketamine or act as a control. Patients in the ketamine group received 0.2 mg/kg on induction of general anesthesia and then 2 mcg kg(-1) hour(-1) for the next 24 hours. Patients were extubated in the operating room and within 15 minutes of arriving in the Post Anesthesia Care Unit (PACU) were started on intravenous patient-controlled analgesia (PCA) hydromorphone without a basal infusion. Patients were assessed for pain (numerical rating scale [NRS]), narcotic use, level of sedation, delirium, and physical therapy milestones until discharge. The ketamine group had significantly less pain during their first postoperative hour in the PACU (NRS 4.8 vs 8.7) and continued to have less pain during the first postoperative day at rest (3.6 vs 5.5) and with physical therapy (5.6 vs 8.0). Three patients in the control group failed PCA pain management and were converted to intravenous ketamine infusions when their pain scores improved. Patients in the ketamine group required less hydromorphone than the control group, but the differences were not significant. Subanesthetic doses of ketamine reduced postoperative pain in narcotic tolerant patients undergoing posterior spine fusions.

Interscalene block anesthesia at an ambulatory surgery center performing predominantly regional anesthesia: a prospective study of one hundred thirty-three patients undergoing shoulder surgery.

Interscalene block (ISB) of the brachial plexus is frequently used for patients undergoing ambulatory shoulder surgery. We previously reported that the incidence of postoperative complaints (neurapraxia) after an ISB was low (3% at 2 weeks), but objective neurologic assessment was not included in the study. The present study combines subjective findings with both preoperative and postoperative objective sensory and motor assessments after an ISB. We prospectively evaluated 133 patients undergoing elective ambulatory shoulder surgery. ISB anesthesia was accomplished by use of 1.5% mepivacaine alone or in combination with bupivacaine (0.5%-0.75%) via a paresthesia technique and a 23-gauge needle. All of the blocks were performed by experienced anesthesiologists. The number of passes with the needle, site of paresthesia, ease of performing the block, and success of the ISB were recorded for each patient. Neurologic assessment was performed preoperatively and up to 2 weeks postoperatively by 1 of 4 health care professionals but not by the anesthesiologists who performed the ISB and included diminished sensation, localized nerve pain, Semmes-Weinstein monofilament pressure threshold sensibility, Weber static 2-point discrimination, and grip strength changes. Patients with postoperative changes were followed up until resolution of symptoms occurred. Successful surgical anesthesia was achieved in 98% of the patients. There was 1 major perioperative complication (0.7%), a seizure that occurred within 5 minutes of the ISB. Two (1.4%) complained of transient postoperative neurapraxias. Neither patient had any changes in objective sensory and motor measurements. Hence, there was no correlation between subjective complaints and objective findings in this study. This study demonstrates that, in the hands of anesthesiologists doing predominantly regional anesthesia, there is a 1.4% incidence of neurologic complications after an ISB. ISB is a safe and effective technique for patients undergoing ambulatory shoulder surgery when an anesthesiologist experienced with regional anesthesia is involved.

Lumbar microdiscectomy under epidural anesthesia: a comparison study.

BACKGROUND CONTEXT: Lumbar microdiscectomy is most commonly performed under general anesthesia, which can be associated with several perioperative morbidities including nausea, vomiting, atelectasis, pulmonary aspiration, and prolonged post-anesthesia recovery. It is possible that fewer complications may occur if the procedure is performed under epidural anesthesia. PURPOSE: To investigate the safety and efficacy of epidural anesthesia in elective lumbar microdiscectomies. STUDY DESIGN: A prospective study evaluating the relative morbidities associated with epidural anesthesia and general anesthesia for lumbar microdiscectomy. PATIENT SAMPLE: Forty-three patients scheduled for primary lumbar microdiscectomy. Two cohorts were formed and were studied separately; one observational of all the 43 patients, and a second cohort of 17 patients who agreed to enter in the randomized trial. OUTCOME MEASURES: The clinical outcome was determined by the presence of postoperative pain, the absence of anesthesia-related complications, and the overall postoperative recovery. METHODS: This was a prospective study. With institutional review board approval, 43 consecutive patients were enrolled in the study. However, only 17 patients agreed to be randomized to receive either general or epidural anesthesia for the procedure; the remaining 26 patients selected the type of anesthesia of their preference. Recorded data for all patients included: age; total surgical time; occurrence of nausea, vomiting, atelectasis, or cardiopulmonary complication; ability to arise out of bed on the day of surgery; and the total number of inpatient hospital days. Postoperative pain and satisfaction were assessed only in the randomized cohort. RESULTS: There were a total of 43 patients, with a mean age of 38.1 years. The patients undergoing epidural anesthesia were marginally older than those undergoing general anesthesia. The epidural and general anesthetic groups were not different with respect to surgical time, pain assessed with a linear visual analogue scale, hospital stay, or the likelihood of arising out of bed on the day of surgery. There were no major cardiopulmonary complications in either group. Patients with epidural anesthesia had significantly less nausea and vomiting. CONCLUSIONS: Epidural anesthesia as an alternative to general anesthesia has shown less postoperative nausea and vomiting in lumbar microdiscectomy. Nevertheless, given the small number of patients, this study should be considered as preliminary, showing small differences in minor potential complications.

Pulmonary injury in patients undergoing complex spine surgery.

BACKGROUND CONTEXT: Previous reports have shown that 15% of patients who undergo sequential anterior, then posterior, surgical corrections for spinal deformities demonstrate evidence of acute lung injury. By analyzing the bronchoalveolar lavage (BAL) fluid from these patients for evidence of acute inflammation, we might gain some insight into the etiology of this acute lung injury. PURPOSE: To elucidate the etiology of acute lung injury after corrective surgery for adult spinal deformities. STUDY DESIGN/SETTING: Fifteen adult patients with scoliosis scheduled for elective sequential anterior then posterior corrective (A/P) spinal deformity surgery. PATIENT SAMPLE: Consecutive adult patients with scoliosis scheduled for elective corrective surgery with the author (OBA). OUTCOME MEASURES: Patients were assessed for postoperative respiratory complications by oxygen requirements, continued mechanical ventilation, and radiological evidence of diffuse bilateral interstitial or alveolar infiltrates. An acute pulmonary inflammatory response included the presence of inflammatory cells and elevated cytokines in BAL fluid. METHODS: BAL were performed after induction of anesthesia but before surgery, at the completion of surgery, and on the morning after surgery with the patient still intubated. BAL fluid was analyzed for inflammatory cells and cytokine interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) levels. Patients were assessed postoperatively for increased pulmonary vascular resistance, radiological evidence of diffuse bilateral alveolar infiltrates, and the requirement for ventilatory support beyond the first postoperative day (POD1). RESULTS: The cell counts of BAL fluid demonstrated significant increases in neutrophils, lymphocytes, and lipid laden macrophages (LLMAC) with surgery. The concentration of the cytokines IL-6 and TNF-alpha also increased with surgery. The elevations in BAL inflammatory cells and cytokine levels correlated positively with increased pulmonary vascular resistance and the requirement for mechanical ventilation. CONCLUSIONS: After A/P spine fusions, patients have evidence of an acute inflammatory pulmonary injury. Several etiologies exist for this finding, including blood and fluid infusions, direct trauma to the lung, a systemic inflammatory response, and the embolization of fat and bone-marrow debris. The presence of LLMAC in the lungs of these patients and the finding that the patient with the requirement for the longest ventilatory support also had the highest BAL LLMAC count, suggest that the embolization of fat and bone debris released from the spine during surgery may be at least partially responsible for the lung injury. Further studies on the mechanism of lung injury during this procedure are warranted.

Pulmonary complications in anterior-posterior thoracic lumbar fusions.

BACKGROUND CONTEXT: Surgery for adult spinal deformity may require both an anterior and posterior approach in order to stabilize the spine and achieve the desired correction. These procedures can be associated with significant pulmonary complications, including atelectasis, pneumonia and respiratory failure. The etiology of some of the respiratory complications is clear: poor inspiratory effort from incision pain and previous pulmonary disease. However, for many patients the direct cause of these complications is not obvious. PURPOSE: To delineate the incidence, severity and risks associated with pulmonary complications in the setting of major spine surgery. STUDY DESIGN/SETTING: Retrospective chart review study of adult patients undergoing combined anterior-posterior thoracic, lumbar and sacral fusion spine surgery. PATIENT SAMPLE: A total of 60 charts were reviewed for this study. OUTCOME MEASURES: Radiographic abnormalities correlated with clinical findings, postoperative need for ventilation and lengths of hospital stay were used as outcome measures. METHODS: Perioperative pulmonary complications were assessed for 60 patients with spinal deformities who underwent combined anterior-posterior thoracic, lumbar and sacral fusion over a 2-year period. RESULTS: One patient was eliminated from analysis because of multiple surgeries during his hospital course. Of the remaining 59 patients, 38 (64%) developed roentgenographic abnormalities. The most common radiographic finding was an effusion found in 66% of these patients, followed by atelectasis in 53%. Twenty-one percent (8 of 38) had infiltrates. Five (5 of 38) or 13% had evidence of partial or complete lobar collapse; in two bronchoscopy was required because of profound hypoxemia. Two patients had pneumonia requiring antibiotic treatment. All but two patients were extubated within 36 hours of surgery. They were kept intubated because of hemodynamic instability. There was no statistically significant difference in the group of patients with and without roentgenographic abnormalities with regard to age, weight, American Society of Anesthesiologists class, smoking history, pulmonary function test results, blood loss, perioperative blood and crystalloid requirement and length of surgery. Patients with radiographic abnormalities were more likely to have had invasion of their thoracic cavity (p=.02) and had a longer mean hospital stay of 13.5 versus 10.2 days (p=.009). CONCLUSION: Radiographic abnormalities of the lungs are common after major spine surgery involving both an anterior and posterior approach, especially when the thoracic cavity is invaded. In view of the morbidity and longer hospital stay associated with such findings, close monitoring of pulmonary status with aggressive pulmonary toilet are indicated.