Medication safety in the operating room: literature and expert-based recommendations.

Human error poses significant risk for hospitalized patients causing an estimated 100,000 to 400,000 deaths in the USA annually. Medication errors contribute, with error occurring in 5.3% of medication administrations during surgery. In this study 70.3% of medication errors were deemed preventable. Given the paucity of randomized controlled studies, we undertook a rigorous review of the literature to identify recommendations supported by expert opinions. An extensive literature search pertaining to medication error, medication safety, operating room, and anaesthesia was performed. The National Guidelines Clearinghouse was searched for any anaesthesia or operating room medication safety guidelines.A total of 74 articles were included. Recommendations were tabulated and assigned points based on a scale revised from a prior study. A total of 138 unique recommendations were identified, with point tallies ranging from 4 to 190. An in-person focus meeting occurred, where the 138 recommendations were reviewed, combined and condensed. A modified Delphi process was used to eliminate items found to be unimportant or those unable to be quantified (e.g. "minimize fatigue"). A total of 35 specific recommendations remained. Adverse events as a result of medication errors occur frequently in the operative setting. There are few rigorous studies to direct medication safety strategies, but this should not lead us to do nothing. The overwhelming consensus regarding best practices should be accepted, and the recommendations implemented. Our list of recommended strategies can hopefully be used to assess local vulnerabilities and institute system solutions.

Effect of postoperative atrial fibrillation on length of stay after cardiac surgery (The Postoperative Atrial Fibrillation in Cardiac Surgery study [PACS(2)].

Atrial fibrillation (AF) after cardiac surgery is thought to increase length of stay (LOS). A clinical pathway focused on the management of postoperative AF, including prophylaxis with beta blockers, was implemented to assess the effect of AF on LOS after cardiac surgery. Data were obtained on consecutive cardiac surgery patients in preoperative normal sinus rhythm, no prior history of AF, and no chronic antiarrhythmic therapy from January to May 1995 (control) and November 1996 to June 1997 (pathway). Statistical analysis was performed to assess the effect of postoperative AF on the LOS, clinical outcomes, and cost after cardiac surgery. Despite the clinical pathway, the LOS (7 days for both periods; p = 0.12) and incidence of AF (28.9% vs 28.4%; p = 0.92) remained unchanged. Unadjusted direct costs were 15% higher in the pathway period (p <0.001). Increased rates of beta-blocker therapy had a marginal effect on the incidence of postoperative AF, except in the group who only underwent primary coronary artery bypass graft surgery (31.2% vs 25.3%; p = 0.31). Multivariate analysis revealed that AF contributed only 1 to 1.5 days to the LOS. Thus, this investigation represents the most recent analysis of the effects of postoperative AF on LOS, clinical outcomes, and cost after cardiac surgery. Unlike prior studies, the impact of postoperative AF is less prominent in the current era of cardiac surgical care regardless of the presence of a clinical pathway addressing AF.

Allosteric modification of oxygen delivery by hemoglobin.

UNLABELLED: Hemoglobin affinity for oxygen is altered by pH, temperature, and high altitude, making oxygen more readily available to the tissues. RSR13 (Allos Therapeutics, Denver, CO), an analog of the drugs clofibrate and bezofibrate, causes a dose-dependent, rightward shift of the oxygen dissociation curve in animals and humans. We tested the safety, pharmacodynamic, and pharmacokinetics of RSR13, an allosteric modifier of hemoglobin, in patients having general surgery in a prospective, randomized, double-blinded, placebo-controlled, dose-escalation clinical trial. After the induction of general anesthesia with endotracheal intubation, 26 patients who consented were randomly assigned to receive an infusion of RSR13 or placebo (2:1) in an ascending dose scheme. Doses studied were 10, 20, 30, 40, 50, 60, 75, and 100 mg/kg infused for 30--60 minutes. Samples were taken for determination of RSR13 concentration in plasma, red blood cells, and urine, as well as for determination of the p50 in blood by using three-point tonometry at frequent intervals after the infusion of the study drug. The RSR13 administration resulted in a dose-dependent rightward shift of the oxygen dissociation curve, with the target p50 shift of 10 mm Hg achieved at the 75- and 100-mg/kg doses. No differences were seen between RSR13 and placebo groups in laboratory or hemodynamic findings, with the exception of a transient, limited increase in serum creatinine in 3 patients who received RSR13. These increases peaked at 48 h (2.2, 3.5, and 4.5 mg/dL respectively), were not associated with oliguria, did not require treatment, and did not prolong hospitalization in any patient. The reasons for the unexplained increases in serum creatinine were not evident, but potentially included surgery itself (nephrectomy), patient condition, or the concomitant administration of renally cleared medications or drugs that affect renal blood flow. IMPLICATIONS: We studied the safety and tolerance of an investigational drug, RSR13 (Allos Therapeutics, Denver, CO), in general surgery patients. This drug, which increases the amount of oxygen available to the body, was well tolerated by the 17 patients who received it. There were clinically relevant increases in serum creatinine in 3 patients, indicating a decrease in renal function, but these increases were short-lived and resolved without treatment.

Improving the thromboresistivity of chemical sensors via nitric oxide release: fabrication and in vivo evaluation of NO-releasing oxygen-sensing catheters.

The development and in vivo analytical performance of a nitric oxide (NO)-releasing amperometric oxygen sensor with greatly enhanced thromboresistivity are reported. Gas permeable coatings formulated with cross-linked silicone rubber (SR) containing NO-generating compounds (diazeniumdiolates) are shown to release NO for extended periods of time (> 20 h) while reducing platelet adhesion and activation. Oxygen-sensing catheters prepared by dip-coating the NO-releasing films over the outer SR tubes of the implantable devices display similar analytical response properties in vitro (sensitivity, selectivity, response times) when compared to analogous sensors prepared without the NO release coatings. Superior analytical accuracy (relative to blood PO2 values measured in vitro) and greatly reduced thrombus formation on the outer surface of the sensors are observed in vivo (in canine model) with the NO release PO2 sensors compared to control sensors (without NO release) implanted simultaneously within the same animals. Based on these preliminary studies, the use of NO release polymers to fabricate catheter-style chemical sensors may be a potential solution to lingering biocompatibility and concomitant performance problems encountered when attempting to employ such devices for continuous intravascular measurements of blood gases and electrolytes.

Preoperative serum potassium levels and perioperative outcomes in cardiac surgery patients. Multicenter Study of Perioperative Ischemia Research Group.

CONTEXT: Although potassium is critical for normal electrophysiology, the association between abnormal preoperative serum potassium level and perioperative adverse events such as arrhythmias has not been examined rigorously. OBJECTIVE: To determine the prevalence of abnormal preoperative serum potassium levels and whether such abnormal levels are associated with adverse perioperative events. DESIGN AND SETTING: Prospective, observational, case-control study of data collected from 24 diverse US medical centers in a 2-year period from September 1, 1991, to September 1, 1993. PATIENTS: A total of 2402 patients (mean [SD] age, 65.1 [10.3] years; 24% female) undergoing elective coronary artery bypass grafting who were not enrolled in another protocol. The study population was identified using systematic sampling of every nth patient, in which n was based on expected total number of procedures at that center during the study period. MAIN OUTCOME MEASURES: Intraoperative and postoperative arrhythmias, the need for cardiopulmonary resuscitation (CPR), cardiac death, and death due to any cause prior to discharge, by preoperative serum potassium level. RESULTS: Perioperative arrhythmias occurred in 1290 (53.7%) of 2402 patients, with 238 patients (10.7%) having intraoperative arrhythmias, 329 (13.7%) having postoperative nonatrial arrhythmias, and 865 (36%) having postoperative atrial flutter or fibrillation. The incidence of adverse outcomes was 3.6% for death, 2.0% for cardiac death, and 3.5% for CPR. Serum potassium level less than 3.5 mmol/L was a predictor of serious perioperative arrhythmia (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.2-4.0), intraoperative arrhythmia (OR, 2.0; 95% CI, 1.0-3.6), and postoperative atrial fibrillation/flutter (OR, 1.7; 95% CI, 1.0-2.7), and these relationships were unchanged after adjusting for confounders. The significant univariate association between increased need for CPR and serum potassium level less than 3.3 mmol/L (OR, 3.3; 95% CI, 1.2-9.5) and greater than 5.2 mmol/L (OR, 3.0; 95% CI, 1.1-8.7) became nonsignificant after adjusting for confounders. CONCLUSIONS: Perioperative arrhythmia and the need for CPR increased as preoperative serum potassium level decreased below 3.5 mmol/L. Although interventional trials are required to determine whether preoperative intervention mitigates these adverse associations, preoperative repletion is low cost and low risk, and our data suggest that screening and repletion be considered in patients scheduled for cardiac surgery.

Impaired neuroendocrine response mediates refractoriness to cardiopulmonary resuscitation in spinal anesthesia.

OBJECTIVE: To determine the extent of neurogenic control on adrenal secretion in a canine model of high spinal anesthesia and cardiac arrest. DESIGN: Randomized, controlled, acute intensive study. SETTING: University intensive care laboratory. SUBJECTS: Nineteen healthy, anesthetized, mongrel dogs. INTERVENTIONS: Cardiac arrest was induced in 11 spinally anesthetized dogs and 8 sham-control animals; cardiopulmonary resuscitation (CPR) was started 60 secs later. Epinephrine was injected at 4 mins and every 2 mins thereafter. Arterial blood samples were obtained before anesthesia, before arrest, and after 1, 3, 5, 7, 9, and 11 mins of CPR. MEASUREMENTS AND MAIN RESULTS: At 1 and 3 mins after cardiac arrest, the control group exhibited significant increases of epinephrine and norepinephrine concentrations (p < .05) that were absent in the spinal anesthesia group. Plasma renin increased in both groups whereas aldosterone and cortisol remained unchanged. CONCLUSIONS: Spinal anesthesia abolishes the catecholamine release that follows cardiac arrest, while a previously postulated direct adrenal effect of hypoxia stimulating catecholamine release was not confirmed in these experiments. Since epinephrine treatment restores coronary perfusion pressure (CPP) during CPR, we conclude that catecholamine deficiency is the most likely mechanism for inadequate CPP during CPR conducted in the presence of spinal anesthesia.

Improved protamine-sensitive membrane electrode for monitoring heparin concentrations in whole blood via protamine titration.

An improved protamine-sensitive electrode based on a polymeric membrane doped with the charged ion exchanger dinonylnaphthalenesulfonate (DNNS) is used for monitoring heparin concentrations in whole blood. The electrode exhibits significant nonequilibrium potentiometric response to polycationic protamine over the concentration range of 0.5-20 mg/L in undiluted whole-blood samples. The sensor can serve as a simple end point detector for the determination of heparin via potentiometric titrations with protamine. Whole-blood heparin concentrations determined by the electrode method (n > or = 157) correlate well with other protamine titration-based methods, including the commercial Hepcon HMS assay (r = 0.934) and a previously reported potentiometric heparin sensor-based method (r = 0.973). Reasonable correlation was also found with a commercial chromogenic anti-Xa heparin assay (r = 0.891) with corresponding plasma samples and appropriate correction for whole-blood hematocrit levels. Whereas a significant positive bias (0.62 kU/L; P < 0.001) is observed between the anti-Xa assay and the protamine sensor methods, insignificant bias is observed between the protamine sensor and the Hepcon HMS tests (0.08 kU/L; P = 0.02). The possibility of fully automating these titrations offers a potentially simple, inexpensive, and accurate method for monitoring heparin concentrations in whole blood.

The effects of a blood-salvaging device on blood containing a hemoglobin-based oxygen carrier, HBOC-201.

OBJECTIVES: Hemoglobin-based oxygen carriers will be used concurrently with intraoperative blood salvage. The effects of salvage and processing on blood containing one such solution (HBOC-201; Biopure Corp, Boston, MA) were studied. DESIGN: Prospective, randomized. SETTING: Laboratory. INTERVENTIONS: Sixteen blood units from healthy volunteers had either HBOC (1,500 mg/dL; n = 10) or normal saline (equivalent volume; n = 6) added. All units were salvaged and processed using a blood salvage device. Samples were analyzed for the concentration and molecular weight distribution of plasma hemoglobin and red cell morphology presalvage (pre) and following processing and washing (post 1). Five of the HBOC units underwent a second 1,000 mL wash (post 2). MEASUREMENTS AND MAIN RESULTS: Processing and washing decreased the concentration of plasma hemoglobin (mg/dL) in HBOC units (1311 +/- 265 pre to 27.8 +/- 19.6 post 1 to 6.5 +/- 2.19 post 2), but did not change the plasma hemoglobin concentration in saline units (2.05 +/- 1.27 pre v 3.18 +/- 0.79 post 1). Total plasma hemoglobin in HBOC units (6.56 +/- 2.19) was significantly greater than in saline units (3.18 +/- 0.79), even after the second wash (post 2). The concentration of unstable hemoglobin in the plasma phase was not different between groups. Red cell morphology was altered by the salvage process but was not different between groups. CONCLUSIONS: Salvage and processing of blood containing HBOC yield concentrated red cells that are indistinguishable from those obtained from blood without HBOC. Residual HBOC remains but is unchanged from the HBOC initially administered.

Clinical evaluation of a prototype motion artifact resistant pulse oximeter in the recovery room.

The frequency and nature of spurious pulse oximetry readings were compared using both a conventional pulse oximeter (CPO) and a prototype Masimo signal extraction technology pulse oximeter (Masimo SET). At a university hospital, 50 ASA physical status I-IV adult patients who underwent general or spinal-epidural anesthesia were selected from a group of 250 patients on the basis of high-alarm generation with routine postoperative pulse oximetry. Pulse oximetry data were recorded simultaneously from both devices with a computer. Overall, the CPO alarm frequency (i.e., oxygen saturation < 90%, or complete signal loss) was once every 13 min, and 87% of these alarms were considered false. Alarms were considered false based on reference electrocardiographs (16 patients), arterial blood gases (7 patients), and clinical assessment. The prototype Masimo SET device alarm frequency was once every 30 min, and 59% of these were considered false. During arm motion with 15 patients, the CPO device produced spurious signals on 54 occasions compared with five for the prototype Masimo SET. The incidence of artifactual pulse oximetry events during patient motion appear to be substantially reduced with the prototype Masimo SET device, relative to a CPO device.

Accuracy and precision of a new, portable, handheld blood gas analyzer, the IRMA.

OBJECTIVE: The accuracy and precision of the new IRMA (Immediate Response Mobile Analysis System, Diametrics, Inc., St. Paul, MN) handheld blood gas analyzer was compared with that of two benchtop blood gas analyzers. The IRMA consists of a notebook-sized machine and disposable cartridges, each containing a pH, a CO2 and an O2 electrode, and provides bedside (point-of-care) blood gas analysis. METHODS: A total of 172 samples (arterial and mixed venous) were obtained from 25 informed, consenting patients undergoing cardiopulmonary bypass. The pH, PCO2 and PO2 of each sample was determined on four blood gas analyzers: NOVA Statlabs Profile 5 (NOVA Biomedical, Waltham, MA), the ABL-50 (Radiometer, West Lake, OH), and two IRMA machines. Linear regression and bias +/- precision were determined, comparing each of the analyzers with the NOVA. RESULTS: All three machines showed a similar, high degree of correlation with the NOVA for pH, PCO2, and PO2. The bias and precision of the IRMA machines compared with the NOVA was similar to that of the ABL compared with the NOVA for pH (NOVA:ABL -0.005 +/- 0.011; NOVA:IRMA 1 = 0.0026 +/- 0.025; NOVA:IRMA 2 = 0.0021 +/- 0.025), for PCO2 (NOVA:ABL = -1.4 +/- 1.3 mmHg; NOVA: IRMA 1 = -1.3 +/- 1.9 mmHg; NOVA: IRMA 2 = -1.2 +/- 2.1 mmHg) and PO2 (NOVA:ABL = 3.6 +/- 21.1 mmHg; NOVA:IRMA 1 = 3.4 +/- 19.9 mmHg; NOVA:IRMA 2 = 6.3 +/- 20.9 mmHg). The bias found for pH, PCO2, and PO2 was not affected by extremes of temperature (range 25.5-40 degrees C) or hematocrit (range 11-44%) for any machine. CONCLUSIONS: The new technology incorporated in the IRMA blood gas analyzer provides results with an accuracy that is similar to that of benchtop analyzers, but with all of the advantages of point-of-care analysis.

Cardiovascular responses during sedation after coronary revascularization. Incidence of myocardial ischemia and hemodynamic episodes with propofol versus midazolam. Institutions of the McSPI Research Group.

BACKGROUND: Propofol sedation offers advantages for titration and rapid emergence in the critically ill patient, but concern for adverse hemodynamic effects potentially limits its use in these patients. The current study compares the cardiovascular effects of sedation with propofol versus midazolam during the first 12 h after coronary revascularization. METHODS: Three hundred fifty-one patients undergoing coronary revascularization were anesthetized using a standardized sufentanil/midazolam regimen, and assigned randomly to 12 h of sedation with either propofol or midazolam while tracheally intubated. The incidence and characteristics of hemodynamic episodes, defined as heart rate less than 60 or greater than 100 beats/min or systolic blood pressure greater than 140 or less than 90 mmHg, were determined using data electronically recorded at 1-min intervals. The presence of myocardial ischemia was determined using continuous three-channel Holter electrocardiography (ECG) and of myocardial infarctions (MI) using 12-lead ECG (Q wave MI, Minnesota Code) or creatine kinase isoenzymes (CK-MB) analysis (non-Q wave MI, peak CK-MB > 70 ng/ml, or CK-MB > 70 IU/I). RESULTS: Ninety-three percent of patients in both treatment groups had at least one hemodynamic episode during the period of postoperative sedation. Propofol sedation resulted in a 17% lower incidence of tachycardia (58% vs. 70%, propofol vs. midazolam; P = 0.04), a 28% lower incidence of hypertension (39% vs. 54%; P = 0.02), and a greater incidence of hypotension (68% vs. 51%; P = 0.01). Despite these hemodynamic effects, the incidence of myocardial ischemia did not differ between treatment groups (12% propofol vs. 13% midazolam; P = 0.66), nor did its severity, as measured by ischemic minutes per hour monitored (8.7 +/- 5.8 vs. 6.2 +/- 4.6 min/h, propofol vs. midazolam; P = 0.19) or ischemic area under the curve (6.8 +/- 4.0 vs. 5.3 +/- 4.2; P = 0.37). The incidence of cardiac death (one per group), Q wave MI (propofol, n = 7; midazolam, n = 3; P = 0.27), or non Q wave MI (propofol, n = 16; midazolam, n = 18; P = 0.81) did not differ between treatment groups. CONCLUSIONS: Hemodynamic episodes occur frequently in the first 12 h after coronary revascularization. Compared with a standard sedation regimen (midazolam), propofol sedation appears to modulate postoperative hemodynamic responses by reducing the incidence and severity of tachycardia and hypertension and increasing the incidence of hypotension. Both sedation regimens appear similarly safe with respect to myocardial ischemia. These findings indicate that propofol infusion provides effective sedation without deleterious hemodynamic effects in patients recovering from cardiac surgery.

A new method of measuring heparin levels in whole blood by protamine titration using a heparin-responsive electrochemical sensor.

OBJECTIVE: To determine the ability of a new electrochemical sensor to determine heparin levels in whole blood and to correlate the heparin levels as determined by this heparin-responsive sensor (HRS) with heparin levels as determined by the Hepcon assay system (Medtronic Hemotec, Parker, CO). DESIGN: Methods comparison study. SETTING: A large academic medical center. INTERVENTIONS: The heparin levels of 162 samples from 24 patients undergoing cardiopulmonary bypass were determined by the HRS system and by the Hepcon system. In 21 samples, heparin levels as measured by anti-Xa activity were determined as well. MEASUREMENTS AND MAIN RESULTS: HRS-determined values correlated highly with Hepcon-determined values (r = 0.942) and with anti-Xa determined values (r = 0.905). Bias +/- precision comparing the HRS and Hepcon methods was 0.211 +/- 0.478 U/mL. CONCLUSIONS: HRS determined that whole blood heparin levels correlate well with Hepcon-determined levels. These limited results indicate that further development and testing of this new technology are warranted.

Dichloroacetate enhanced myocardial functional recovery post-ischemia : ATP and NADH recovery.

This study was undertaken to determine the effect of dichloroacetate (DCA) on myocardial functional and metabolic recovery following global ischemia. Isolated rabbit hearts were subjected to 120 min of mildly hypothermic (34 degrees C), cardioplegic arrest with multidose, modified St. Thomas' cardioplegia. Hearts were reperfused with either physiologic salt solution (PSS) as controls, (CON, n = 10) or PSS containing DCA (DCA, n = 6) at a concentration of 1 mM. Functional and metabolic indices were determined at baseline and at 15, 30, and 45 min of reperfusion. In four DCA and four CON hearts, myocardial biopsies were taken at baseline, end-ischemia, 15 and 45 min for nucleotide levels. Functional recovery was significantly better in hearts reperfused with DCA as demonstrated by recovery of baseline developed pressure (DCA = 69 +/- 5%, CON = 45 +/- 9%) and dP/dt (DCA = 64% +/- 10% versus CON = 48% +/- 10%). Coronary blood flow was not different between groups either at baseline or during reperfusion, but myocardial oxygen consumption (MVO2) was increased in the DCA versus CON hearts (79% +/- 20% of baseline vs 50% +/- 18%). Recovery of myocardial adenylate energy status was improved in the DCA versus CON hearts (ATP recovered to 45% +/- 20% versus 8% +/- 6% of baseline). Coronary sinus lactate concentration was decreased in DCA perfused hearts at 45 min of reperfusion. Percent of baseline NADH values was similar at 15 min of reperfusion, but at 45 min, DCA hearts showed a decrease in NADH levels, while CON hearts showed an increase (DCA = 48%; CON = 121%). The enhanced myocardial function and improved metabolic status noted with DCA may result from increased oxidative phosphorylation due to altered pyruvate dehydrogenase (PDH) activity.

Near-infrared spectroscopy: theory and applications.

In conclusion, NIRS appears to offer both a new monitoring modality and new information about cerebral oxygenation. Technical problems in the application of this technology persist, most notably determination of pathlength and the volume of tissue interrogated. Those familiar with the history of pulse oximetry will recall that although Millikan developed an ear oximeter in 1947, it was not until Aoyagi combined recognition of the pulse signal with spectroscopy in the 1970s that oximetry was transformed into a clinically applicable monitor. In much the same way, NIRS may find the same tremendous usefulness as a noninvasive monitor of cerebral oxygen utilization, pending resolution of the remaining technical problems.

A pilot study of the effects of a perflubron emulsion, AF 0104, on mixed venous oxygen tension in anesthetized surgical patients.

A pilot study of a perfluorochemical (PFC) emulsion was undertaken to determine whether administration of a perflubron emulsion could result in measurable changes in mixed venous oxygen tension. Seven adult surgical patients received a 0.9-g PFC/kg intravenous dose of perflubron emulsion after acute normovolemic hemodilution (ANH). Hemodynamic and oxygen transport data were collected before and after ANH, immediately after PFC infusion, and at approximate 15-min intervals throughout the surgical period. There were no clinically significant hemodynamic changes associated with the administration of the PFC emulsion. There was a significant increase in mixed venous oxygen tension (PVO2) after the PFC infusion, while cardiac output and oxygen consumption were unchanged. As surgery progressed, the hemoglobin concentration decreased with ongoing blood loss while PVO2 values remained at or above predosing levels. Peak perflubron blood levels were 0.8 g/dL immediately postinfusion, and approximately 0.3 g/dL at 1 h. This pilot study demonstrates that administration of perflubron emulsion results in measurable changes in mixed venous oxygen tension during intraoperative ANH.

Coronary perfusion pressure during cardiopulmonary resuscitation after spinal anesthesia in dogs.

Cardiac arrest during spinal anesthesia is a rare event, but when it does happen cardiopulmonary resuscitation (CPR) is often ineffectual. This study examines the effect of spinal anesthesia on coronary perfusion pressure (CPP) during CPR and the subsequent response of CPP to epinephrine administration. Twenty mongrel dogs were anesthetized, and randomly assigned to a spinal injection with either 0.5 mg/kg bupivacaine or with an equivalent volume of normal saline. Twenty minutes later, ventricular fibrillation was electrically induced and after 1 min CPR was started. CPP was measured every minute. After 4 min of CPR, epinephrine 0.01 mg/kg was given followed by 0.1, 0.2, and 0.4 mg/kg epinephrine intravenously (IV) at 6, 8, 10 min of CPR, respectively. The bupivacaine (n = 11) group had significantly less CPP than the sham spinal (n = 8) group, 12-13 mm Hg as compared to 27-34 mm Hg. Only 4/11 dogs (36%) in the bupivacaine group had CPP > or = 15 mm Hg during the first 4 min after arrest as compared to 8/8 (100%) in the sham spinal group. This increased to 7/11 dogs (64%) after 0.01 mg/kg epinephrine and to 9/11 after 0.1 mg/kg epinephrine. Total spinal anesthesia decreases CPP and thus the efficacy of CPR in dogs below the threshold previously established for predicting successful resuscitation. Epinephrine is effective in increasing CPP during CPR above the critical threshold. These data suggest that if cardiac arrest occurs during spinal anesthesia, epinephrine should be given in doses of 0.01-0.02 mg/kg IV initially and then increasing to 0.1 mg/kg IV. When this does not work, and ineffective CPR is suspected, alternative resuscitative measures should be considered.

Pulse oximetry.

Pulse oximetry is a reliable, noninvasive, easy to use means of continuously determining arterial oxygen saturation in virtually any setting. This article details the historical and technical development of this monitor; reviews the literature on application, accuracy, and response; and presents an overview of future advances.