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We have proposed a novel hypothesis regarding the potential role of occupational or second-hand exposure in physician substance use, abuse, and addiction. While only 5.6% of licensed physicians in Florida are anesthesiologists, nearly 25% of physicians followed for substance abuse/dependence are anesthesiologists. When we sort by drug of choice, anesthesiologists have more opioid abuse and dependence than other physicians and appropriate controls. Abuse of one opioid, fentanyl, appears to be increasing and has been noted among the State of Florida's causes of opioid deaths. Fentanyl and sufentanyl are commonly administered highly potent opioid analgesics, as much as 80-800 times as potent as morphine. We have recent data from the State of Florida impaired physicians database, which has allowed us to categorize all fentanyl abusing and/ or dependent physicians. Just knowing that a physician abuses fentanyl gives you a good clue as to their specialty; 75% are anesthesiologists! While drug abuse researchers, oncologists and others who handle drugs of abuse everyday, have no greater incidence of opioid abuse or dependence, anesthesiologists are at the top of every list. Can this be due to just access and stress? We have proposed an alternative hypothesis of second hand exposure. To test this hypothesis, we developed a sensitive LC/MS/MS assay to measure the intravenous anesthetic and analgesic agents, propofol and fentanyl in air. Not only did we detect propofol and fentanyl in cardiovascular surgery operating room air, we also found the highest concentrations were close to the patient's mouth where anesthesiologists work for hours. Like tobacco, second hand opioid exposure can sensitize and change the brain making abuse, dependence and behavioral disorders more likely. Thus environmental exposure and sensitization may be an important risk factor in physician addiction. Second hand exposure may affect treatment outcome and explain anesthesiologist's inability to return to work in the operating room. We are developing an animal model for second hand exposure and additional studies of the operating room and cardiac anesthesiologists are underway. [ABSTRACT FROM AUTHOR]

Background: The nasal ala is an attractive site for pulse oximetry because of perfusion by branches of the external and internal carotid arteries. We evaluated the accuracy of a novel pulse oximetry sensor custom designed for the nasal ala., Methods: After IRB approval, healthy non-smoking subjects [n=12; aged 28 (23-41) yr; 6M/6F] breathed hypoxic mixtures of fresh gas by a facemask to achieve oxyhaemoglobin saturations of 70-100% measured by traditional co-oximetry from radial artery samples. Concurrent alar and finger pulse oximetry values were measured using probes designed for these sites. Data were analysed using the Bland-Altman method for multiple observations per subject., Results: Bias, precision, and accuracy root mean square error (ARMS) over a range of 70-100% were significantly better for the alar probe compared with a standard finger probe. The mean bias for the alar and finger probes was 0.73% and 1.90% (P<0.001), respectively, with corresponding precision values of 1.65 and 1.83 (P=0.015) and ARMS values of 1.78% and 2.72% (P=0.047). The coefficients of determination were 0.96 and 0.96 for the alar and finger probes, respectively. The within/between-subject variation for the alar and finger probes were 1.14/1.57% and 1.87/1.47%, respectively. The limits of agreement were 3.96/-2.50% and 5.48/-1.68% for the alar and finger probes, respectively., Conclusions: Nasal alar pulse oximetry is feasible and demonstrates accurate pulse oximetry values over a range of 70-100%. The alar probe demonstrated greater accuracy compared with a conventional finger pulse oximeter., (© The Author [2014]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

A breath-based adherence system to document ingestion of oral medications (e.g., HAART) was investigated. Specifically, the food additive 2-butanol, which can be easily packaged with a drug, is converted via alcohol dehydrogenase to the volatile metabolite 2-butanone that rapidly appears in breath, indicating adherence. In healthy adults using a portable sensor and GC-MS, the following experiments were performed: yield of 2-butanone in breath following ingestion of 2-butanol, adherence system accuracy, and potential interference of the adherence system by food or misplacement of 2-butanol on the tongue. During feasibility testing, every subject exhaled 2-butanone with 6.6 ± 1.5 min to peak concentrations of 548 ± 235 ppb following ingestion of 2-butanol (40 mg). ROC areas at 5 and 10 min were 0.95 (0.86-1.00) and 1.00 (1.00-1.00). Food did not interfere. Tongue application resulted in large concentrations of 2-butanol, but not 2-butanone. A breath test to provide definitive evidence of oral medication adherence appears technically feasible.

Adherence to microbicide gel use is critical to optimizing effectiveness in preventing human immunodeficiency virus transmission. The authors hypothesized that ester taggants added to vaginal gels would generate exhaled alcohol and ketone metabolites and provide a "breath test" for vaginal gel use. This 2-arm (vaginal and dermal), randomized, participant-blinded, pilot study tested this hypothesis. On 8 visits, healthy women (n = 8) received intravaginal taggant (2-butyl acetate, 2-pentyl acetate, isopropyl butyrate, or 2-pentyl butyrate; 30 mg) formulated in hydroxyethylcellulose or tenofovir placebo gel. A second group (n = 4) of women received the same formulations administered dermally on the forearm to determine if skin administration might confound the system. Breath samples were collected using bags before and after taggant administration for 1 hour. Samples were measured using a miniature gas chromatograph and/or gas chromatography-mass spectroscopy for ester taggant, alcohol, and ketone concentrations. After vaginal administration, 2-butyl acetate, 2-pentyl acetate, and metabolites were observed in breath, whereas isopropyl butyrate, 2-pentyl butyrate, and metabolites were not. Some women reported self-resolving, mild burning (24/64 visits) with vaginal administration or a "bubblegum" taste (7/64 visits). No taggants or metabolites were detected following dermal application. A "breath test" for adherence to antiretroviral vaginal gel application appears physiologically and technically feasible., (© 2012 The Author(s).)

We designed and built a novel, miniature gas chromatograph (mGC) to use exhaled breath to estimate blood ethanol concentrations that may offer GC quality sensitivity and specificity, but with portability, reduced size, and decreased cost. We hypothesized that the mGC would accurately estimate the serum ethanol concentration using exhaled breath. Human subjects (n = 8) were dosed with ethanol employing the Widmark criteria, targeting a blood concentration of 0.08 g/dL. Serum and breath samples were collected concurrently over an hour. Ethanol concentrations in serum were measured using a CLIA-approved laboratory. Ethanol concentrations in conventional breath were assayed using a calibrated mGC or Intoxilyzer 400PA. Data were analyzed using Bland-Altman analysis using serum concentrations as a "gold standard". For the mGC, the regression line (correlation coefficient), bias, and 95% limits of agreement were y = 1.013x - 0.009 (r = 0.91), -0.008 g/dL, and -0.031 to 0.016 g/dL, respectively, for 30 specimens. For the Intoxilyzer 400PA, the regression line (correlation coefficient), bias, and 95% limits of agreement were y = 0.599x + 0.008 (r = 0.86), -0.024 g/dL, and -0.049 to 0.002 g/dL, respectively, for 71 specimens with a large magnitude effect. We concluded that the mGC, using exhaled breath, performed well to estimate the serum ethanol concentrations.

Poor compliance to prescribed medication regimens in clinical trials continues to be a major obstacle to drug development success and cost reduction, and there is no gold standard technology that is cheap and effective to reliably measure drug compliance. This paper presents a new drug compliance scheme based on the detection of volatile markers in exhaled breath using a commercial off-the-shelf electronic nose (e-nose) system. A mouth air collection system was developed and interfaced with an e-nose for automated sampling and analysis of breath samples. Advanced signal processing techniques were used to develop classifiers for discriminating between blank breath and breaths masked with volatiles. The compliance monitor was able to achieve 100% detection rate in separating a volatile tagged breath from a blank breath, and 98% discrimination rate between volatile types. The proposed compliance monitor demonstrates a cheap and reliable method of measuring drug compliance in clinical trials.

We hypothesize that aerosolization of anesthetics administered intravenously to patients in the operating room may be an unintended source of exposure to physicians. This may lead to inadvertent sensitization, which is associated with an increased risk for developing addiction. This may contribute to the over-representation of certain specialties among physicians with addiction. We retrospectively reviewed the de-identified demographic information of all licensed physicians treated for substance abuse in the State of Florida since 1980, to determine if medical specialty was associated with addiction in this group of individuals. Then, to identify the potential for exposure, two mass spectrometry assays were developed to detect two intravenously administered drugs, fentanyl and propofol, in air. Since 1980, 7.6% of licensed Florida physicians underwent treatment for addiction. Addiction in anesthesiologists was higher than expected. Opiate abuse was greater in anesthesiologists and surgeons compared to other specialties. Aerosolized fentanyl was detected in the air of the cardiothoracic operating room, in patients' expiratory circuits, and in the headspace above sharps boxes, but not in adjoining hallways. Aerosolized propofol was detected in the expirations of a patient undergoing transurethral prostatectomy. While access and stress may place anesthesiologists and surgeons at greater risk for substance abuse, an additional risk factor may be unintended occupational exposure to addictive drugs. This report provides preliminary evidence of detection of aerosolized intravenous anesthetics using two newly developed analytical methods. We conclude that the potential exists for chronic exposure to low levels of airborne intravenously administered drugs. Further studies are under way to determine the significance of this exposure.

Background: The purpose of this study is to test precision and systematic bias of a target controlled infusion (TCI) of propofol in human volunteers at two sedative concentrations., Methods: We studied the 'Diprifusor' model (Marsh Pharmacokinetics and a Graseby 3400 infusion pump) in 18 human volunteers at two sedative target plasma concentrations (0.5 and 1.0 microg ml(-1)). Twenty minutes after infusion start or change and 20 min after discontinuation of the infusion plasma propofol concentrations were measured using liquid chromatography-mass spectroscopy (LC-MS). Plasma propofol concentrations were compared with concentrations predicted by the TCI system. Agreement of those two measures (precision and bias) was determined using regression analysis., Results: We found little systematic bias but poor precision. When setting the TCI system to deliver a plasma concentration of 1.0 microg ml(-1) one can predict the actual plasma concentration with 95% confidence only within a range of 0.44-1.38 microg ml(-1)., Conclusions: This finding helps to explain differences in responses to propofol sedation; pharmacokinetic variability appears to be an important factor.

Unlabelled: The testing of pulse oximeter probes is generally limited to the integrity of the electrical circuit and does not include the optical properties of the probes. Few pulse oximeter testers evaluate the accuracy of both the monitor and the probe. We designed a study to compare the accuracy of nonproprietary probes (OSS Medical) designed for use with Nellcor, Datex-Ohmeda, and Criticare pulse oximeter monitors with that of their corresponding proprietary probes by using a commercial off-the-shelf pulse oximeter tester (Index). The Index pulse oximeter tester does include testing of the optical properties of the pulse oximeter probes. The pulse oximeter tester was given a controlled input that simulated acute apnea. Desaturation curves were automatically recorded from the pulse oximeter monitors with a data-collection computer. Comparisons between equivalent proprietary and nonproprietary probes were performed. Data were analyzed by using univariate and multivariate general linear model analysis. Five OSS Medical probe models were statistically better than the equivalent proprietary probes. The remainder of the probes were statistically similar. Comparative and simulation studies can have significant advantages over human studies because they are cost-effective, evaluate equipment in a clinically relevant scenario, and pose no risk to patients, but they are limited by the realism of the simulation., Implications: We studied the performance of pulse oximeter probes in a simulated environment. Our results show significant differences between some probes that affect the accuracy of measurement.

Background: The authors compared the performance of a prototype intubation aid that incorporated plastic illumination and image guides into a stylet with fiberoptic bronchoscopy and direct laryngoscopy for tracheal intubation by novice users., Methods: In a randomized, nonblinded design, patients were assigned to direct laryngoscopy, fiberoptic bronchoscopy, or imaging stylet intubation groups. The quality of laryngeal view and ease with which it was attained for each intubation was graded by the laryngoscopist. Time to intubation was measured in 1-min increments. A sore-throat severity grade was obtained after operation., Results: There were no differences in demographic, physical examination, or surgical course characteristics among the groups. The laryngoscope produced an adequate laryngeal view more easily than did the imaging stylet or bronchoscope (P = 0.001) but caused the highest incidence of postoperative sore throat (P<0.05). Although the time to intubation for direct laryngoscopy was shorter than for imaging stylet, which was shorter than fiberoptic bronchoscopy (P<0.05), the quality of laryngeal view with the imaging stylet was inferior to both direct laryngoscopy and fiberoptic bronchoscopy techniques (P<0.05)., Conclusions: Novices using the imaging stylet produce fewer cases of sore throat (compared with direct laryngoscopy) and can intubate faster than when using a bronchoscope in anesthetized adult patients. The imaging stylet may be a useful aid for tracheal intubation, especially for those unable to maintain skills with a bronchoscope.

Objectives: To review the operational characteristics of commercial devices used to detect endotracheal intubation; and to identify an ideal device for detecting endotracheal intubation in emergency situations, especially in the prehospital setting during cardiac arrest., Data Sources: Relevant articles from the medical literature are referenced., Study Selection: The authors identified the need for understanding the basic operation principles of portable devices used to detect endotracheal intubation and to correctly use them in unpredictable clinical situations., Data Extraction: Data from published literature., Data Synthesis: Recently, a number of new portable devices have been marketed for detecting endotracheal intubation, each having advantages and disadvantages, especially when used during emergency situations. The devices are classified based on their principle of operation. Some rely on CO2 detection (STATCAP, Easy Cap, and Pedi-Cap), others utilize the transmission of light (Trachlight, SURCH-LITE), one operates based on reflection of sound energy (SCOTI), and some depend on aspiration of air (TubeChek and TubeChek-B). A brief description of each device and its operational characteristics are reviewed. A comparative analysis among the devices is made based on size, portability, cost, ease of operation, need for calibration or regular maintenance, reliability for patients with and without cardiac arrest, and the possibility of use for adult and pediatric patients. False-negative and false-positive results for each device are also discussed. False-negative results mean that although the endotracheal tube is in the trachea, the device indicates it is not. False-positive results mean that although the endotracheal tube is in the esophagus, the device indicates it is in the trachea., Conclusions: Although no clinical comparative study of commercial devices to detect endotracheal intubation exists, the syringe device (TubeChek) has most of the characteristics necessary for a device to be considered ideal in emergency situations in the prehospital setting. It is simple, inexpensive, easy to handle and operate, disposable, does not require maintenance, gives reliable results for patients with and without cardiac arrest, and can be used for almost all age groups. The device may yield false-negative results, most commonly in the presence of copious secretions and in cases of accidental endobronchial intubation. Regardless of the device used, clinical judgment and direct visualization of the endotracheal tube in the trachea are required to unequivocally confirm proper endotracheal tube placement.

Background: The need for ventilation during the initial management of cardiac arrest is an important public health problem that is being debated. The present study was designed to determine whether ventilation affects return of spontaneous circulation from cardiac arrest in a swine model with an interval of untreated ventricular fibrillation of 6 minutes, as reported in witnessed out-of-hospital human cardiac arrest., Methods and Results: Twenty-four animals were randomly assigned to two groups: one that received ventilation during the first 10 minutes of chest compression and one that did not. Coronary perfusion pressure and minute ventilation were continuously recorded. Arterial and mixed venous blood gases were measured at intervals. Return of spontaneous circulation was defined prospectively as an aortic systolic blood pressure of > 80 mm Hg for > 5 minutes and was the primary outcome variable. All animals were anesthetized, paralyzed, and intubated. Ventricular fibrillation was induced and persisted for 6 minutes without chest compression, followed by mechanical chest compression for 10 minutes and then attempted defibrillation. Animals without return of spontaneous circulation were given epinephrine, ventilation, and chest compression for an additional 3 minutes. Defibrillation was again attempted, and animals were assessed for return of spontaneous circulation. There were no significant differences between the two groups in baseline prearrest mean cardiac index, coronary perfusion pressure, or arterial and mixed venous blood gases. However, after 9 minutes of chest compression, significant differences were noted between the ventilated and nonventilated groups. The nonventilated group had significantly (P < .05) lower mean arterial PO2 (38 +/- 17 mm Hg compared with 216 +/- 104 mm Hg) and higher PCO2 (62 +/- 16 mm Hg compared with 35 +/- 8 mm Hg), lower mixed venous PO2 (15 +/- 7 mm Hg compared with 60 +/- 7 mm Hg). Nine of 12 (75%) of the ventilated animals, and only 1 of 12 (8%) of the nonventilated animals had return of spontaneous circulation after cardiac arrest (P < .002)., Conclusions: In this animal model of cardiac arrest, ventilation was important for resuscitation. The importance of ventilation could be related to the prolonged duration of untreated ventricular fibrillation and the significantly greater hypoxia and hypercarbic acidosis found in the nonventilated animals.

Objectives: To investigate how minute ventilation affects the partial pressure of end-tidal CO2 and arterial and mixed venous pH, PCO2, PO2, and the concentration of bicarbonate during low blood-flow states. We tested the null hypothesis that acid-base conditions during low rates of blood flow are not significantly different when minute ventilation is doubled or halved., Design: Prospective, experimental, animal study., Setting: University hospital laboratory., Subjects: Domestic swine., Interventions: We studied ten anesthetized and mechanically ventilated swine (weight, 43 to 102 kg) in a new model of controlled systemic and pulmonary blood flow in which each animal was maintained on ventricular assist devices. After electrical induction of ventricular fibrillation, ventricular assist device blood flow was decreased in steps. At each decrease, control minute ventilation, two times the control minute ventilation (hyperventilation), and one-half the control minute ventilation (hypoventilation) were administered; each ventilatory change was maintained for 6 mins., Measurements and Main Results: Aortic, pulmonary arterial and central venous pressures, ventricular assist device blood flow, and end-tidal CO2 were recorded continuously. Acid-base conditions were studied at three different mean blood flow rates: 49%, 30%, and 12% of baseline prearrest cardiac index. Arterial pH and PaO2 and mixed venous pH varied directly (p < .003) with minute ventilation, while PaCO2 and mixed venous PCO2, and end-tidal CO2 varied inversely (p < .0001) with minute ventilation. Mixed venous PO2 was not significantly related to minute ventilation (p = .6). PaCO2 and arterial bicarbonate; mixed venous pH, mixed venous PO2, and mixed venous bicarbonate, and end-tidal CO2 varied directly (p < .001) with blood flow, while mixed venous PCO2 varied inversely with blood flow (p < .05). Arterial pH was not significantly related to blood flow (p = .3). When minute ventilation changed from hyperventilation to hypoventilation at a mean blood flow rate of 49%, mean arterial pH decreased 0.22 +/- 0.06 (p < .05), mean PaCO2 increased 28 +/- 6 torr (3.7 +/- 0.8 kPa) (p < .05), and mean PaO2 decreased 99 +/- 77 torr (13.2 +/- 10 kPa); mean mixed venous pH decreased 0.11 +/- 0.02, mean mixed venous PCO2 increased 16 +/- 2.2 torr (2.1 +/- 0.3 kPa) (p < .05), and mean mixed venous PO2 did not change; mean end-tidal CO2 increased 18 +/- 2 torr (2.4 +/- 0.3 kPa) (p < .05). The effect of changes in minute ventilation on blood gases and end-tidal CO2 was similar for mean blood flow rates of 30% and 12% of baseline cardiac index., Conclusions: During low rates of blood flow similar to those rates found in shock and cardiopulmonary resuscitation, alterations in minute ventilation significantly influenced end-tidal CO2 and both arterial and mixed venous pH and PCO2. These findings may have clinical importance in improving the treatment of shock and cardiac arrest.

Objective: To compare the tidal volume, minute ventilation, and gas exchange caused by mechanical chest compression with and without mechanical ventilatory support during cardiopulmonary resuscitation (CPR) in a laboratory model of cardiac arrest., Design: A laboratory swine model of CPR was used. Eight animals with and eight animals without mechanical ventilation received chest compression (100/min) for 10 min. Coronary perfusion pressure, tidal volume, and minute ventilation were recorded continuously., Interventions: Ventricular fibrillation for 6 min without CPR, then mechanical chest compression for 10 min., Results: During the first minute of chest compression, mean (+/- S.D.) minute ventilation was 11.2 +/- 5.9 l/min in the mechanically ventilated group and 4.5 +/- 2.8 l/min in the group without mechanical ventilation (P = 0.01). Minute ventilation gradually declined to 5.8 +/- 1.4 l/min and 1.7 +/- 1.6 l/min, respectively, during the last minute of chest compression (P < 0.0001). After 10 min of chest compression, mean arterial pH was significantly more acidemic in the group without mechanical ventilation (7.16 +/- 0.13 compared with 7.30 +/- 0.07 units) and PCO2 was higher (62 +/- 19 compared with 35 +/- 9 mmHg). Mixed venous PCO2 was also higher (76 +/- 15 compared with 61 +/- 8 mmHg)., Conclusion: Standard chest compression alone produced measurable tidal volume and minute ventilation. However, after 10 min of chest compression following 6 min of untreated ventricular fibrillation, it failed to sustain pulmonary gas exchange as indicated by significantly greater arterial and mixed venous hypercarbic acidosis when compared with a group receiving mechanical ventilation.

Study Objective: A number of studies have shown that expired CO2 concentration is closely related to cardiac output, but that cardiac output was not controlled as an independent variable. In addition, the partial pressure of end-tidal CO2 (PETCO2) during extremely low cardiac output has not been reported. The objective of the present study was to measure PETCO2 during well-controlled, very low blood flow rates under conditions of constant minute ventilation., Design: Ten anesthetized, intubated, and mechanically ventilated swine (weight, 43 to 102 kg) were placed on two ventricular assist devices in order to control cardiac output. Minute ventilation was measured and kept constant. Ventricular assist device output (measured with an ultrasonic flow probe); PETCO2; and aortic, pulmonary artery, and central venous pressures were recorded continuously., Interventions: After electrical induction of ventricular fibrillation, pump output was decreased in steps., Measurements and Main Results: Cardiac index ranged from 0 to 5,371 mL/min/m2; 59% of PETCO2 measurements were made at cardiac indexes of less than 1,313 mL/min/m2 (30 mL/min/kg). The relationship of PETCO2 levels to cardiac index was determined with linear regression analysis; P < .05 was statistically significant. PETCO2 correlated significantly with cardiac index (P < .0001). The best-fit line by least-squares analysis produced the equation: PETCO2 = 4.98 + 0.012 [cardiac index] (r2 = .82)., Conclusion: Under conditions of constant minute ventilation, PETCO2 correlated closely with cardiac index over a large range of blood flow rates, including extremely low rates.

We evaluated high-flow intravenous devices designed specifically for fluid resuscitation of infants and children. Fluid flow rates with 4-, 5-, and 6-Fr high-flow sheaths and 18-, 20-, and 22-gauge catheters were measured and compared. Flow rate is significantly faster with the 4-Fr sheath (P less than 0.0001) than with the 18-, 20-, or 22-gauge catheter. The high flow rates possible with the sheaths make them ideal for use in patients who require rapid fluid resuscitation.

Background: As intra- and interhospital transportation of ventilator-dependent patients has become more commonplace, the number of portable transport ventilators has increased. Transport ventilators should be capable of delivering consistent tidal volume (VT) from breath to breath following changes in lung-thorax compliance and airways resistance. We sought to determine the effect of changes in compliance (C) and resistance (R) on the VT delivered by eight commercially available, time-cycled transport ventilators., Methods & Materials: Each ventilator (PneuPAC Model 2, Autovent 3000, MAX, Bird Transport Mini-TXP, IC-2A, P7, E100i, and Logic 07a) was connected to a calibrated pneumotachograph and a test lung set for normal adult C (C = 100 mL/cm H2O [1.02 L/kPa]) and R (R = 2 cm H2O.s.L-1 [0.2 kPa.s.L-1]), with VT at 1,000 mL., Results: As C and R were manipulated, VT varied widely. Tidal volume decreased least with the P7 and most with the Bird transport ventilator., Conclusion: Decreases in VT with a transport ventilator predispose patients to hypoventilation, hypercapnia, and acidemia. Tidal volume often is not monitored continuously during transport, yet large decreases in VT must not be allowed when pulmonary mechanics are unstable. Internal pressure-limiting valves, venturi flow-generating devices, and compression volume in the breathing circuit are at least three factors that affect VT with transport ventilators.

Current standards for ventilation during cardiopulmonary resuscitation are not supported by recent and ongoing investigation. This is particularly true in victims with an unprotected airway. Currently used flow rates and inspiratory times predispose to gastric insufflation and its complications. Potential changes and corrections that may benefit the victim of cardiac arrest are reviewed.

In the 1980 Standards and Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiac Care, the recommended method for determining cardiac arrest in infants was changed from palpation of the apical impulse to palpation of the brachial pulse. The importance of adequately assessing the heart beat before initiating chest compressions due to the potential hazards is well established. This study was designed to ascertain which pulse parents could palpate most readily and accurately count within a given time. The results demonstrated the brachial pulse was much easier to palpate and more accurately counted by parents than the apical impulse. These findings formed the basis for the 1980 revised recommendation for determining cardiac arrest in infants.

Artificial ventilation is a cornerstone of basic life support-cardiopulmonary resuscitation (BLS-CPR). Recent data corroborate clinical studies performed in the 1950s and 1960s, suggesting a need to change the present American Heart Association standards for artificial ventilation. These studies show that gastric insufflation followed by regurgitation and pulmonary aspiration are a major hazard of artificial ventilation with an unprotected airway. Present BLS-CPR standards require that ventilation be performed rapidly between external chest compressions or with incremental breaths. These methods of ventilation predispose the victim to gastric insufflation. Alternative methods of ventilation with longer inspiratory time and thus lower flow rate and peak inspiratory pressure are suggested. Additionally, rescue personnel, particularly EMTs and paramedics, should be taught how to apply cricoid pressure to prevent gastric insufflation in victims with an unprotected airway.

Cardiopulmonary resuscitation (CPR) is the principal means for combating death caused by cardiac arrest in the prehospital setting. Adequate evaluation of CPR standards, however, requires exacting replication of both positive pressure ventilation and cardiac compression protocols over sufficient time periods to measure effects on arterial blood gases, hemodynamics, and intrapulmonary shunting. The programmable cardiopulmonary resuscitator studied provides for such highly controlled CPR protocols. It is developed from a cardiopulmonary resuscitator that has been adapted to accommodate a universal programmable timer. The programmable cardiopulmonary resuscitator permits independent changes in rate, duration, and sequence of both positive pressure ventilation and cardiac compression. Hence, it makes possible the simulation of one-rescuer and two-rescuer CPR standards, as well as the investigation of alternative CPR techniques.

Current American Heart Association standards for ventilation during two-rescuer CPR recommend that a 0.8- to 1.2-L breath be delivered in 0.5 second after every fifth chest compression. Delivering a high-volume breath over a brief inspiratory time (TI) may lead to hypoventilation and gastric insufflation in victims with an unprotected airway. We reasoned that lengthening TI would lower peak inspiratory pressure and peak inspiratory flow rate, and thus improve lung inflation. To study this possibility, a mechanical model of the airway and upper gastrointestinal tract was designed. A ventilator delivering a sinusoidal wave form was used to simulate artificial ventilation. A 0.8-L breath was delivered at 0.5, 1.0, or 1.5 seconds at three lung compliances (CLs). Also, the effect of lengthening TI was studied with increased airway resistance. Lengthening TI improved lung inflation and decreased gastric insufflation at all CLs, but more so with normal CL than with decreased CL. This study demonstrates the need for evaluating alternative ventilatory patterns with longer TI during CPR.