Association between anaemia and hospital readmissions in patients undergoing major surgery requiring postoperative intensive care.

Anaemia is a common sequela of surgery, although its relationship with patient recovery is unclear. The goal of this investigation was to assess the associations between haemoglobin concentrations at the time of hospital discharge following major surgery and early post-hospitalisation outcomes, with a primary outcome of 30 day unanticipated hospital readmissions. This investigation includes data from two independent population-based observational cohorts of adult surgical patients (aged ≥ 18 years) requiring postoperative intensive care unit admission between 1 January 2010 and 31 December 2019 in hospitals in Olmsted County, Minnesota, and between 1 July 2010 and 30 June 2017 in the Kaiser Permanente Northern California integrated healthcare system, California. Cox proportional hazards models assessed the associations between discharge haemoglobin concentrations (per 10 g.l-1 ) and outcomes, with prespecified multivariable adjustment. A total of 3260 patients were included from Olmsted County hospitals and 29,452 from Kaiser Permanente Northern California. In adjusted analyses, each 10 g.l-1 decrease in haemoglobin at hospital discharge was associated with a 9% (hazard ratio 1.09, 95%CI 1.02-1.18; p = 0.014) and 8% increase (hazard ratio 1.08, 95%CI 1.06-1.11; p < 0.001) in the hazard for readmission within 30 days in Olmsted County and Kaiser Permanente Northern California, respectively. In a sensitivity analysis exploring relationships across varying levels of pre-operative anaemia severity, these associations remained consistent, with lower discharge haemoglobin concentrations associated with higher readmissions irrespective of pre-operative anaemia severity. Anaemia at hospital discharge in surgical patients requiring postoperative intensive care is associated with increased rates of hospital readmission in two large independent cohorts. Future studies are necessary to evaluate strategies to prevent and/or treat anaemia in these patients for the improvement of post-hospitalisation outcomes.

Regionally selective effects of NMDA receptor antagonists against ischemic brain damage in the gerbil.

This study compared the ability of three N-methyl-D-aspartate (NMDA) receptor antagonists to prevent neuronal degeneration in an animal model of global cerebral ischemia. The model employed is characterized by damage to the striatum, hippocampus, and neocortex. Antagonists were administered to gerbils either before or after a 5-min bilateral carotid occlusion. The intraischemic rectal temperature was either maintained at 36-37 degrees C or allowed to fall passively to 28-32 degrees C. Antagonists and doses tested were 1 and 10 mg/kg of MK-801 (pre- or postischemia), 30 mg/kg of CGS 19755 preischemia, four 25 mg/kg doses of CGS 19755 administered between 0.5 and 6.5 h postischemia, and 40 mg/kg of MDL 27,266 (pre- or postischemia). All three NMDA receptor antagonists exhibited some degree of neuroprotective activity when the carotid occlusion was performed under normothermic conditions. Most of the treatments with antagonist markedly reduced striatal damage. CA1 hippocampal and neocortical pyramidal cells were spared by only three of the treatments, however, and the extent of neuroprotection varied widely from case to case. Toxic doses of antagonist were required to protect CA1 pyramidal cells from ischemic damage. Ischemic damage to hippocampal areas CA2-CA3a and CA4 appeared to be resistant to all of these treatments. Most CA1 pyramidal cells that were protected from degeneration by an NMDA receptor antagonist were histologically abnormal. The neuroprotective effects of MK-801 and intraischemic hypothermia appeared to be additive. MK-801 (10 mg/kg) consistently reduced the postischemic brain temperature, but only the magnitude of hypothermia produced soon after reperfusion correlated with its neuroprotective action. These results suggest that NMDA receptor antagonists are relatively poor neuroprotective agents against a moderately severe ischemic insult.

Prior blood transfusions and Alzheimer's disease.

We performed a population-based, case-control study to evaluate prior blood transfusion as a potential risk factor for Alzheimer's disease (AD). All cases were incident cases of AD from 1975 to 1984 with residence for 40 years or more in Olmsted County, Minnesota, prior to their onset of dementia (N = 252). There was one age- and gender-matched control for each case. We ascertained the number of blood transfusions prior to the age of onset of dementia and the corresponding year in each control. Sixty-five cases and 55 controls had at least one prior blood transfusion. We did not find a significantly increased risk of AD for the events of at least one, three, or six blood transfusions.

Perioperative neuropathies.

Neuropathies are infrequent but potentially debilitating complications in surgical patients. Although the most common of these affect the peripheral ulnar and sciatic nerves, more centrally located sets of nerves such as the brachial plexus and lumbosacral nerve roots also can be affected perioperatively. Traditionally, these neuropathies have been considered avoidable and associated with inappropriate patient positioning intraoperatively. Recent epidemiologic and anatomic studies suggest, however, that various factors other than intraoperative positioning may contribute to the development of neuropathies. For example, it is now clear that a large proportion of surgical patients who subsequently have development of ulnar neuropathies are asymptomatic during the first several postoperative days. Further delineation of the epidemiology and causes of the various perioperative neuropathies should lead to innovative interventions and clinical trials of their effectiveness to decrease the frequency and severity of these complications in surgical patients.

Postoperative use of epidurally administered morphine in children and adolescents.

Epidurally administered narcotics are increasingly used to provide relief of pain in adults after major surgical procedures. This report describes the use of epidurally administered morphine for postoperative analgesia in nine pediatric patients after 15 major surgical procedures. The mean dose of morphine was 0.12 +/- 0.03 mg/kg of body weight, and the mean duration of analgesia per dose was 10.8 +/- 4.0 hours. Catheters remained in place for a mean duration of 50.3 +/- 16.0 hours. Increasing the dose of morphine to more than 0.1 mg/kg did not prolong the duration of analgesia but it did increase the frequency of side effects. No complications from placement of the catheter and no serious side effects were encountered. The postoperative requirements for narcotics were significantly less in the patients who received morphine epidurally than in those who received narcotics parenterally. Epidurally administered morphine can provide reliable postoperative analgesia in pediatric patients. The potential benefits include improved quality of pain relief at low total requirements, improved pulmonary function, and early ambulation.

Preoperative laboratory screening in healthy Mayo patients: cost-effective elimination of tests and unchanged outcomes.

We reviewed the results of preoperative screening laboratory tests in asymptomatic healthy patients who underwent elective surgical procedures at our institution in 1988. Substantially abnormal results were found in 160 of 3,782 patients. All such abnormalities involved five tests: aspartate aminotransferase, glucose, potassium, platelet count, and hemoglobin. Thirty of the abnormal test results were predictable on the basis of the history or physical examination. The abnormal test result prompted further assessment in 47 patients. No surgical procedure was delayed, and no association was noted between adverse outcome and any preoperative laboratory abnormality. Because of our findings in this analysis and similar studies on specific tests from other institutions, we no longer require preoperative laboratory screening tests for healthy patients.

Effects of referral bias on surgical outcomes: a population-based study of surgical patients 90 years of age or older.

During the 11-year period 1975 through 1985, 1,063 surgical procedures were performed on 795 Mayo Clinic patients 90 years of age or older. Preoperative conditions, surgical setting, and perioperative morbidity and mortality were analyzed in a comparison of the local residents of Olmsted County, Minnesota (N = 224), with patients from outside the county but within 250 miles (N = 456) or referrals from a distance of 250 miles or further (N = 115). In comparison with non-Olmsted County patients, Olmsted County patients were generally older, had more preoperative chronic diseases, and underwent more emergency operations. Patients who had traveled 250 miles or more to the Mayo Clinic were more likely to be men and referred for cancer-related surgical procedures. The risks of major morbidity and mortality within 48 hours postoperatively were increased in patients with more preoperative chronic diseases and those undergoing emergency procedures, characteristics most common in Olmsted County patients. Because of differences in these factors between groups, perioperative risks averaged over our entire patient series underestimated risks that would be expected from a population-based cohort such as Olmsted County residents. In general, data from tertiary medical centers probably do not accurately reflect overall practice or outcomes in community settings.

Outcomes of patients with no laboratory assessment before anesthesia and a surgical procedure.

OBJECTIVE: To estimate the frequency of perioperative morbidities in patients who underwent anesthesia and a surgical procedure with no preoperative laboratory testing. MATERIAL AND METHODS: We conducted an electronic database search of medical records of 56,119 patients who underwent surgical or diagnostic procedures and anesthesia at Mayo Clinic Rochester in 1994 and found 5,120 who had no laboratory tests done within 90 days before the procedure. From this group, we randomly selected 1,044 patients (87 from each month) to document the absence of preoperative tests, the presence of preexisting disease (by organ system), the type of anesthetic agent, and the outcomes and tests intraoperatively and postoperatively. RESULTS: The 1,044 patients ranged in age from 0 to 95 years (median age, 21). No deaths or major perioperative morbidities occurred (0.0%; exact 95% confidence interval, 0.00 to 0.35%). Although 10 patients underwent blood typing and screening for antibodies immediately preoperatively, no blood transfusions were necessary. Intraoperatively, 17 laboratory tests and 1 electrocardiogram were obtained, and 3 results were abnormal. Postoperatively, 42 blood tests and 2 electrocardiographic procedures were performed. Five of the 42 blood tests showed abnormal results (hemoglobin levels in 3, serum sodium in 1, and arterial blood gases in 1). One electrocardiogram showed normal findings, and the other revealed normal results except for premature ventricular contractions. No laboratory test done intraoperatively or postoperatively was found to change surgical or medical management substantially. One patient who had unanticipated blood loss during an outpatient procedure was admitted to the hospital for observation. CONCLUSION: All 1,044 patients, 97% of whom were relatively healthy, with no recent laboratory testing safely underwent anesthesia and an operation. We conclude that patients who have been assessed by history and physical examination and determined to have no preoperative indication for laboratory tests can safely undergo anesthesia and operation with tests obtained only as indicated intraoperatively and post-operatively. Current anesthetic and medical practices rapidly identify perioperative indications for laboratory evaluation as they arise.

Malignant pheochromocytoma masquerading as acute pancreatitis--a rare but potentially lethal occurrence.

Pheochromocytoma mimicking acute pancreatitis as its initial clinical manifestation is a known, albeit rare, phenomenon. Herein we describe a patient with this occurrence. A striking feature was pronounced hyperamylasemia, almost exclusively of the S-type. Our theory is that the pheochromocytoma caused a catecholamine-induced cardiomyopathy, which contributed to failure of the left ventricle; pulmonary edema and release of S-type amylase from hypoxic lung tissue occurred subsequently.

Outcomes of noncardiac surgical procedures in children and adults with congenital heart disease. Mayo Perioperative Outcomes Group.

OBJECTIVE: To assess the outcomes and risk factors for morbidity associated with anesthesia and noncardiac surgical procedures in children and adults with congenital heart disease. DESIGN: We conducted a retrospective cohort study of the 6-year period from January 1987 through November 1992 at one of the Mayo-affiliated hospitals in Rochester, Minnesota. MATERIAL AND METHODS: In all children and adults 50 years of age or younger with congenital heart disease who underwent one or more noncardiac surgical or diagnostic procedures and anesthesia, we analyzed the risk factors for 30-day perioperative morbidity and mortality. RESULTS: The overall frequency of complications among the 276 patients who underwent 480 noncardiac surgical procedures and anesthesia was 5.8% (28 of 480), and only 1 patient died intraoperatively. Major risk factors univariately associated with complications for the first procedures (15 of 276 patients or 5.4%) included the presence of cyanosis (P = 0.002), current treatment for congestive heart failure (P<0.001), poor general health (P<0.001), and younger age at the time of the procedure (P = 0.027). Procedures performed on the respiratory and nervous systems also were associated with high frequencies of complications. Complications in patients undergoing ambulatory surgical procedures were infrequent (1.7%). CONCLUSION: The frequency of perioperative complications in children and adults who have congenital heart disease and undergo noncardiac surgical procedures and anesthesia is low. Patients who have pulmonary hypertension, congestive heart failure, or cyanosis and children with congenital heart disease who are younger than 2 years of age have an increased frequency of perioperative morbidity.

Clinical implications of variation in total venoarterial shunt fraction calculated by different methods during severe acute respiratory failure.

Ventilation-perfusion imbalance is the major physiologic disturbance that produces hypoxemia in acute respiratory failure, and total venoarterial shunt fraction is frequently used as a measure of its severity. Ninety-one total venoarterial shunt fractions were calculated from 29 patients with severe acute respiratory failure. Four different methods were used for each estimation, only two of which considered the influence of cardiac output and tissue oxygen uptake. The differences among the results were statistically significant and rendered invalid those that were calculated independently of mixed venous oxygen values. Lack of uniformity of the methods that have been used for calculating shunts in respiratory failure makes it difficult to compare individual patients or groups of them from previous reports. Use of a standard method is desirable so that statistical evaluation of severity and response to treatment can be undertaken. Older data on which therapeutic decisions may be based can have misleading variability from those derived from currently accepted techniques and could appreciably influence patient care.

The effects of intraoperative blood salvage and induced hypotension on transfusion requirements during spinal surgical procedures.

Spinal surgical procedures, such as placement of Harrington rods for correction of scoliosis, are associated with considerable perioperative blood loss and, hence, with the risks associated with homologous blood transfusions. To test the hypothesis that intraoperative autologous blood transfusions could decrease the amount of homologous blood needed in such operations, we conducted a two-part study: (1) a retrospective review of 142 patients in whom blood salvage was not used and (2) a prospective review of 28 patients who received autologous transfusions. Intraoperative autologous transfusion reduced the amount of homologous blood required by more than 50% (5.1 versus 2.0 units; P less than 0.001). The total amount of homologous blood required during the hospital stay was also significantly reduced by intraoperative autologous transfusion (6.0 versus 3.4 units; P less than 0.001). Induced hypotension in 81 of the 142 patients who did not receive autologous transfusions did not decrease the homologous blood transfusion requirements from those needed by the normotensive patients. We conclude that intraoperative autologous transfusion significantly reduces the need for homologous blood products in patients who undergo spinal surgical procedures. Induced hypotension, which did not affect transfusion requirements in our study, should be further evaluated in a blinded, prospective study.

Role of preoperative cessation of smoking and other factors in postoperative pulmonary complications: a blinded prospective study of coronary artery bypass patients.

The association between preoperative smoking cessation and postoperative pulmonary morbidity was studied prospectively in 200 consecutive patients undergoing an elective coronary artery bypass surgical procedure. Detailed respiratory, cardiovascular, and smoking histories were elicited. Preoperative arterial blood gas analyses and bedside spirometry were performed. Urinary cotinine levels were measured to verify smoking histories. During spirometry, severe angina developed in seven patients, who were hence excluded from the study; one patient died of hemorrhage intraoperatively. An observer unaware of patients' preoperative histories assessed the remaining 192 patients throughout the intraoperative and postoperative periods for pulmonary complications. Postoperative pulmonary complications occurred in a third of the current smokers. Patients who had stopped smoking for 2 months or less had a pulmonary complication rate almost 4 times that of patients who had stopped for more than 2 months (57.1% versus 14.5%). Patients who had stopped smoking for more than 6 months had rates similar to those who had never smoked (11.1% and 11.9%, respectively). Preoperative pulmonary dysfunction, increased pack-years of smoking, prolonged surgical time, and the use of enflurane were independently associated with postoperative pulmonary morbidity (P less than 0.05). We concluded that smoking cessation should occur at least 2 months preoperatively to maximize the reduction of postoperative respiratory complications.

Monitoring and analysis of oxygenation and ventilation during rigid bronchoscopic neodymium-YAG laser resection of airway tumors.

Neodymium-YAG (yttrium-aluminum-garnet) laser resection of obstructing and inoperable tumors of the large airways is used as palliative therapy to improve the quality of survival in patients by alleviating airway obstruction. Rapid changes in oxygenation and ventilation can occur during these procedures. In a study of 14 patients, transcutaneous oxygen (PtcO2) and carbon dioxide (PtcCO2) monitors responded slowly to these changes and frequently provided misleading values. Pulse oximetry (SNO2) accurately reflected arterial oxygen saturation but did not indicate severe desaturation until arterial oxygen tension approached dangerously low values. Thus, we did not find PtcO2 or PtcCO2 monitoring to be clinically useful during neodymium-YAG laser resection of airway tumors through a rigid bronchoscope. SNO2 was clinically useful and accurate; however, a large decrement in oxygenation may occur before changes in oxygen saturation ensue and are detected.

Alzheimer's disease and cumulative exposure to anesthesia: a case-control study.

OBJECTIVE: To evaluate prior exposure to general anesthesia as a potential risk factor for Alzheimer's disease (AD). DESIGN: A retrospective, population-based, case-control study. SETTING: The Rochester Epidemiology Resource. PATIENTS: Cases were all incident cases of AD from 1975 to 1984 who resided for 40 years or more in Olmsted County prior to the onset of their dementia (n = 252). One age- and gender-matched control for each case was selected from all registrations for care at Mayo Clinic during the year of onset in the incident case. The case and control groups each had 252 individuals. Of these, 208 cases and 199 controls had at least one exposure to general anesthesia prior to the year of onset of dementia in the matched AD patient. MEASUREMENTS: The cumulative duration of anesthesia and the total number of general anesthetic exposures prior to the age of onset of dementia and the corresponding year in each matched control were ascertained. RESULTS: There was no significant difference in mean cumulative exposure (in minutes) to general anesthesia (patients vs controls: 188.4 vs 170.5 minutes, ns). Neither exposure to six or more episodes of general anesthesia (OR = 1.44; 95% CI: 0.77-2.71) nor cumulative exposure to 600 minutes or more of general anesthesia (OR = 1.63; 95% CI: 0.53-5.04) were associated with a significantly increased risk of AD. CONCLUSION: It is unlikely that multiple exposures to general anesthesia increase the risk of AD.

Outcomes of anesthesia and surgery in people 100 years of age and older.

OBJECTIVE: To assess the outcomes of anesthesia and surgery for men and women 100 years of age and older. DESIGN: Retrospective cohort study in the 20-year time period from 1975 to 1994, with follow-up through 1995. SETTING: Mayo-affiliated hospitals and Olmsted Community Hospital, Rochester, Minnesota. PARTICIPANTS: All men and women 100 years of age and older who underwent surgery at a participating hospital. MEASUREMENTS: Forty-eight-hour and 30-day perioperative morbidity and mortality; long-term survival. RESULTS: Thirty-one men and women aged 100 to 107 years underwent 42 procedures. One major complication (3%) within 48 hours was observed. The 48-hour, 30-day, and 1-year mortality rates were 0%, 16.1%, and 35.5%, respectively. When compared with survival rates for age-, gender-, and calendar year of birth-matched peers from the general population, the survival rate for centenarians who underwent surgery and anesthesia was comparable to the rate expected. CONCLUSION: These data suggest that people 100 years of age and older who have operable diseases or injuries should not be denied surgical interventions because of perceived risks associated with their advanced age.

Prior intra-operative hypotension is not a risk factor for development of Alzheimer's disease.

OBJECTIVE: A retrospective, population-based, case-control study was carried out to evaluate episodes of prior intra-operative hypotension as a potential risk factor for Alzheimer's disease (AD). METHODS: Patients were all incident cases of AD from 1975-1984 who resided for 40 years or more in Olmsted County prior to their onset of dementia (N = 252). One age and gender-matched control for each case was selected from all registrations for care at Mayo Clinic during the year of onset in the incident case. Each case and control group had 252 individuals. RESULTS: Of these, 27 cases and 32 controls had at least one ten minute or longer episode of intra-operative hypotension of a systolic blood pressure of less than 90 mm Hg prior to the year of onset of dementia in the matched AD patient. We did not find a significantly increased risk of AD for hypotensive episodes of less than 75 or 90 mm Hg. CONCLUSIONS: It is unlikely that intra-operative hypotensive events of this degree increase the risk of AD.

Digital perfusion of handball players. Effects of repeated ball impact on structures of the hand.

The effect of repeated ball impacts on the handball player's hands was studied by using thermography and routine roentgenography to determine evidence of altered perfusion or other tissue changes. Seventeen of 22 players had multiple areas of decreased perfusion. 12 of these 17 were symptomatic and 8 showed definite correlation between symptoms and thermographic findings. No skeletal or articular changes were noted. Players with more than 200 hr of accumulated playing time had increased risk of developing symptomatic, although nonprogressive, alterations in perfusion of their hands but did not have evident skeletal changes.

Benign and malignant tumors of the orbital cavity including the lacrimal gland.

CT and MR imaging are the modalities of choice in the assessment of orbital neoplasia. When combined with the clinical history and examination, radiologic imaging can provide valuable information regarding tumor diagnosis. Imaging studies thus enable the clinician to delineate the extent of disease and plan the surgical approach for biopsy or excision. In some cases, serial orbital imaging is used to monitor for tumor growth or recurrence.