Objectives: To obtain reliable estimates of the effects of neuraxial blockade with epidural or spinal anaesthesia on postoperative morbidity and mortality. Design: Systematic review of all trials with randomisation to intraoperative neuraxial blockade or not. Studies: 141 trials including 9559 patients for which data were available before 1 January 1997. Trials were eligible irrespective of their primary aims, concomitant use of general anaesthesia, publication status, or language. Trials were identified by extensive search methods, and substantial amounts of data were obtained or confirmed by correspondence with trialists. Main outcome measures: All cause mortality, deep vein thrombosis, pulmonary embolism, myocardial infarction, transfusion requirements, pneumonia, other infections, respiratory depression, and renal failure. Results: Overall mortality was reduced by about a third in patients allocated to neuraxial blockade (103 deaths/4871 patients versus 144/4688 patients, odds ratio=0.70, 95% confidence interval 0.54 to 0.90, P=0.006). Neuraxial blockade reduced the odds of deep vein thrombosis by 44%, pulmonary embolism by 55%, transfusion requirements by 50%, pneumonia by 39%, and respiratory depression by 59% (all P Conclusions: Neuraxial blockade reduces postoperative mortality and other serious complications. The size of some of these benefits remains uncertain, and further research is required to determine whether these effects are due solely to benefits of neuraxial blockade or partly to avoidance of general anaesthesia. Nevertheless, these findings support more widespread use of neuraxial blockade.

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Reduction of postoperative mortality and morbidity with epidural or spinal anaesthesia: results from overview of randomised trials.

The safe sedation of children for procedures requires a systematic approach that includes the following: no administration of sedating medication without the safety net of medical supervision; careful presedation evaluation for underlying medical or surgical conditions that would place the child at increased risk from sedating medications; appropriate fasting for elective procedures and a balance between depth of sedation and risk for those who are unable to fast because of the urgent nature of the procedure; a focused airway examination for large tonsils or anatomic airway abnormalities that might increase the potential for airway obstruction; a clear understanding of the pharmacokinetic and pharmacodynamic effects of the medications used for sedation, as well as an appreciation for drug interactions; appropriate training and skills in airway management to allow rescue of the patient; age- and size-appropriate equipment for airway management and venous access; appropriate medications and reversal agents; sufficient numbers of people to carry out the procedure and monitor the patient; appropriate physiologic monitoring during and after the procedure; a properly equipped and staffed recovery area; recovery to presedation level of consciousness before discharge from medical supervision; and appropriate discharge instructions. This report was developed through a collaborative effort of the American Academy of Pediatrics and the American Academy of Pediatric Dentistry to offer pediatric providers updated information and guidance in delivering safe sedation to children.

https://pediatrics.aappublications.org/content/pediatrics/118/6/2587.full.pdf

Guidelines for Monitoring and Management of Pediatric Patients Before, During, and After Sedation for Diagnostic and Therapeutic Procedures.

A surgical staple line reinforcement device for use with a variety of surgical staplers having a pivoted connection between stapler arms or jaws, such as endoscopic stapler devices. The device comprises a pair of tubes of bio-implantable material connected together at a hinge. The device can be quickly and easily applied to a surgical stapler by a surgical team to provide tissue reinforcement. The hinged connection of the device provides both for secure attachment of the device to the surgical stapler, and for a barrier to protect the pivot connection from contamination by migrating tissue during operation. Preferably, tear lines are provided on each of the tubes to assist in removing excess material following attachment of staples. The device allows for fast and safe staple reinforcement and rapid stapler separation and removal following installation.

Endoscopic device and method for reinforcing surgical staples

A surgical stapling apparatus having tissue bolstering material releasably attached thereto for application of the material and staples to body tissue is disclosed. The tissue bolstering material is preferably releasably held to surfaces of the stapling apparatus through pins, clips or similar securing structures. The tissue bolstering material can be either planar or tubular in configuration. Preferably, both the anvil portion and the fastener ejecting portion of the stapler are at least partially covered with the tissue bolstering material. In use, tissue is disposed between the anvil portion and the stapling portion of the instrument and the instrument is fired. The tissue bolstering material is thereby secured to the tissue and releasably detaches from the stapler upon withdrawal of the stapler from the surgical site.

Surgical stapling apparatus and method

A surgical staple line reinforcement device for use with a variety of surgical staplers to protect against tissue damage from surgical staples. The device comprises a tube of bio-implantable material that can be quickly and readily applied by a surgical team to provide tissue reinforcement. The device preferably comprises a stretched or expanded polytetrafluoroethylene (PTFE) with pre-established tear lines therein. The device allows for fast and safe staple reinforcement and rapid stapler separation and removal following installation.

Device and method for reinforcing surgical staples

The performance of three commercially available pulse oximeters was assessed in five anesthetized dogs in which increasing levels of methemoglobin were induced. Hemoglobin oxygen saturation in each dog was monitored with three pulse oximeters (Nellcor N-100, Ohmeda 3700, and Novametrix 500) and a mixed venous saturation pulmonary artery catheter (Oximetrix Opticath). Arterial and mixed venous blood specimens were analyzed for PaO2, PaCO2, and pHa using standard electrodes. An IL-282 Co-oximeter was used on the same specimens to determine oxyhemoglobin and methemoglobin as percentages of total hemoglobin. Methemoglobin levels of up to 60% were induced by intratracheal benzocaine. As MetHb gradually increased while the dogs were breathing 100% inspired oxygen, the pulse oximeter saturation (SpO2) overestimated the fractional oxygen saturation (SaO2) by an amount proportional to the concentration of methemoglobin until the latter reached approximately 35%. At this level the SpO2 values reached a plateau of 84-86% and did not decrease further. When, at fixed methemoglobin levels, additional hemoglobin desaturation was induced by reducing inspired oxygen fraction, SpO2 changed by much less than did SaO2 (regression slopes from 0.16 to 0.32). Thus, at high methemoglobin levels SpO2 tends to overestimate SaO2 by larger amounts at low hemoglobin saturations. Plots of SpO2 versus functional saturation (oxyhemoglobin/reduced hemoglobin plus oxyhemoglobin) show an improved but still poor relationship (regression slopes from 0.32 to 0.46). The Oximetrix Opticath pulmonary artery catheter behaves similarly but provides somewhat better agreement with functional saturation than do the pulse oximeters in the presence of methemoglobinemia. Pulse oximetry data (SpO2) should be used with caution in patients with methemoglobinemia.

Effects of methemoglobinemia on pulse oximetry and mixed venous oximetry

Background : Pulse oximetry is considered a standard of care in both the operating room and the postanesthetic care unit, and it is widely used in all critical care settings. Pulse oximeters may fail to provide valid pulse oximetry data in various situations that produce low signal-to-noise ratio. Motion artifact is a common cause of oximeter failure and loss of accuracy. This study compares the accuracy and data dropout rates of three current pulse oximeters during standardized motion in healthy volunteers. Methods : Ten healthy volunteers were monitored by three different pulse oximeters : Nellcor N-200, Nellcor N-3000, and Masimo SET (prototype). Sensors were placed on digits 2, 3, and 4 of the test hand, which was strapped to a mechanical motion table. The opposite hand was used as a stationary control and was monitored with the same pulse oximeters and an arterial cannula. Arterial oxygen saturation rate was varied from 100% to 75% by changing the inspired oxygen concentration. While pulse oximetry was both constant and changing, the oximeter sensors were connected before and during motion. Oximeter errors and dropout rates were digitally recorded continuously during each experiment. Results : If the oximeter was functioning before motion began, the following are the percentages of time when the instrument displayed a pulse oximetry value within 7% of control : N-200 = 76%, N-3000 = 87%, and Masimo = 99%. When the oximeter sensor was connected after the beginning of motion, the values were N-200 = 68%, N-3000 = 47%, and Masimo = 97%. If the alarm threshold was chosen as pulse oximetry less than 90%, then the positive predictive values (true alarms/total alarms) are N-200 = 73%, N-3000 = 81%, and Masimo = 100%. In general, N-200 had the greatest pulse oximetry errors and N-3000 had the highest dropout rates. Conclusions : The mechanical motions used in this study significantly affected oximeter function, particularly when the sensors were connected during motion, which requires signal acquisition during motion. The error and dropout rate performance of the Masimo was superior to that of the other two instruments during all test conditions. Masimo uses a new paradigm for oximeter signal processing, which appears to represent a significant advance in low signal-to-noise performance

Effects of Motion on the Performance of Pulse Oximeters in Volunteers

Background We describe the anesthetic management for a new surgical procedure: laser ablation of emphysematous bullae via thoracoscope. Although thoracoscopy is not new, this is the first description of a series of patients with bilateral, chronic lung disease who underwent long periods of one-lung ventilation (OLV) during thoracoscopic therapy. Methods Twenty-six laser ablation procedures were performed in 22 patients. The patients were elderly (mean age 63 yr) with a large incidence of coexisting cardiovascular disease. Most required chronic home oxygen therapy. Patients were monitored invasively, and hemodynamic data were recorded every 5 min. Arterial blood gas analyses were performed every 15 min. Comparisons were made between three Intraoperative periods: two-lung ventilation (TLV) before thoracoscopy, OLV during thoracoscopy, and TLV after thoracoscopy. Results All patients survived the operation despite a mean OLV duration of 170 min, but several experienced serious intraoperative problems, such as hypoxemia or hypotension. Hypoxemia was treated with nondependent lung continuous positive airway pressure and dependent lung positive end-expiratory pressure. In all patients the lungs were adequately ventilated, but bronchopleural fistulae occurred upon return to TLV in every case. The resulting air leaks, often 50% of inspired tidal volume, required the use of a pressure-cycled ventilator to maintain oxygenation. Postoperative air leaks greater than 50% of inspired tidal volume usually required subsequent surgical correction, while smaller leaks resolved spontaneously. Mechanical ventilation was required for an average of 5 days. Eighty-four percent have survived at least 6 months, and nearly all survivors report symptomatic improvement. Conclusions Ablation of bullae appears to provide symptomatic improvement, and thoracoscopy might be better tolerated than thoracotomy, especially in patients with severe bullous emphysema.

Anesthesia for Thoracoscopic Laser Ablation of Bullous Emphysema

This study compares two noninvasive techniques for monitoring the partial pressure of carbon dioxide (Pco2) in 24 anesthetized adult patients. End-tidal PCO2 (PETCO2) and transcutaneous Pco2 (PtcCO2) were simultaneously monitored and compared with arterial Pco2 (PaCO2) determined by intermittent analysis of arterial blood samples. PETCO2 and PtcCO2 values were compared with PaCO2 values corrected to patient body temperature (PaC02T) and PaCO2 values determined at a temperature of 37°C (PaCO2). Linear regression was performed along with calculations of the correlation coefficient (r), bias, and precision of the four paired variables:PETCO2 versus PaCO2 and PaCO2T (n = 211), and PtcCO2 versus PaCO2 and PaCO2T (n = 233). Bias is defined as the mean difference between paired values, whereas precision is the standard deviation of the difference.

Noninvasive monitoring of carbon dioxide: a comparison of the partial pressure of transcutaneous and end-tidal carbon dioxide with the partial pressure of arterial carbon dioxide.

The accuracy of pulse oximetry (for pulse hemoglobin oxygen saturation [SpO2]) and mixed venous oximetry (for mixed venous hemoglobin oxygen saturation [SvO2]) was assessed during progressive normovolemic anemia in dogs. Splenectomized mongrel dogs under general anesthesia were monitored with a three-wavelength pulmonary artery oximeter catheter (10 dogs) and a pulse oximeter (11 dogs). Data were collected while fractional inspired oxygen concentration (FIO2) was varied from 1.00 to 0.05 in seven steps. The dogs then underwent isovolemic hemodilution, and the FIO2 was again varied. This sequence continued until data no longer could be obtained. The accuracy of each device was assessed by determining the bias (the average difference between the continuous monitor oximeter and the bench oximeter) and the precision (the standard deviation of the difference). For the three-wavelength Oximetrix catheter (for hemoglobin oxygen saturation denoted here SoxO2), the overall bias (SoxO2 - SvO2) and precision were -0.7 +/- 8.6% for the 193 data points. The accuracy as assessed by bias and precision for SoxO2 was similar for hematocrits of 40-15%. (Bias +/- precision was 2.1 +/- 5.7% for hematocrits greater than 40%, and -1.1 +/- 7.5% for hematocrits of 15% to 19%). At hematocrits between 10 and 14%, the precision worsened to 12%, and for hematocrits less than 10% the bias +/- precision was -11.5 +/- 11.8%. The overall SpO2 accuracy was 0.2 +/- 7.6% for 178 points. The pulse oximeter's accuracy was similar, down to hematocrits of 10%. Below 10%, the bias and precision worsened to -5.4 +/- 18.8%.(ABSTRACT TRUNCATED AT 250 WORDS)

Steven J. Barker

Papers

Effects of methemoglobinemia on pulse oximetry and mixed venous oximetry

Effects of Motion on the Performance of Pulse Oximeters in Volunteers

Anesthesia for Thoracoscopic Laser Ablation of Bullous Emphysema

Noninvasive monitoring of carbon dioxide: a comparison of the partial pressure of transcutaneous and end-tidal carbon dioxide with the partial pressure of arterial carbon dioxide.

Effects of anemia on pulse oximetry and continuous mixed venous hemoglobin saturation monitoring in dogs