Emergency medicine resident patient care documentation using a hand-held computerized device

OBJECTIVE

To determine whether emergency medicine (EM) resident documentation of procedures, patient encounters, and patient follow-ups improved after implementation of a personal digital assistant (PDA) hand-held recording system.

METHODS

All first-year EM residents were provided a PalmV (Palm, Inc., Santa Clara, CA) PDA. A customized patient procedure and encounter program was constructed using Pendragon Forms (Pendragon Software Corporation, Libertyville, IL) and loaded into each PDA. Residents were instructed to enter information on patients who had any of 21 procedures performed or were considered to be clinically unstable. These data were downloaded to the residency coordinator's desktop computer. The mean number of procedures, encounters, and follow-ups performed per resident were then compared with those of a group of 36 historical controls from the three previous first-year resident classes who recorded the same information using a handwritten card system. Data from the historical controls were combined and the means of each group were compared by Student's t-test.

RESULTS

Mean documentation of three procedures was significantly increased in the PDA group versus the index card system: conscious sedation 5.8 vs. 0.03 (p < 0.000005), thoracentesis 2.2 vs. 0.0 (p = 0.002), ultrasound 6.3 vs. 0.0 (p = 0.002). The mean numbers of pericardiocenteses and unstable pediatric surgical patient evaluations were significantly decreased in the hand-held group [from 1.2 to 0.4 (p = 0.03) and from 9.1 to 2.2 (p = 0.02), respectively]. Patient follow-up documentations were not statistically different between the two groups.

CONCLUSIONS

Use of a hand-held PDA was associated with an increase in first-year EM resident documentation in three of 20 procedures and a decrease in one procedure and the number of unstable surgical pediatric patient resuscitations. The overall time savings in constructing a resident procedure database, as well as the other uses of the PDAs, may make transition to a hand-held computer-based procedure log an attractive option for EM residencies.

Rapid development of brain hypothermia using femoral-carotid bypass

OBJECTIVES

Advances in the field of cardiopulmonary resuscitation have led to an increasing number of patients initially surviving sudden cardiac arrest. Unfortunately, most of these patients do not recover from the resultant anoxic brain insult. Several animal and human trials have suggested that post-resuscitative brain hypothermia may improve neurologic recovery after cardiopulmonary arrest. Present cooling methods are slow, induce only brain surface cooling, or result in systemic hypothermia. The authors tested the hypothesis that unilateral hypothermic carotid bypass would induce bilateral brain cooling without evoking systemic hypothermia or hemodynamic instability.

METHODS

Anesthetized, ventilated common swine (n = 6, 24-37 kg) underwent right femoral and carotid artery bypass cannulation. Central and peripheral hemodynamic parameters were recorded every 2 minutes throughout the procedure. Thermodynamic parameters included bilateral frontal lobe, bilateral nasopharyngeal, pulmonary artery, and rectal temperatures. Hypothermic femoral-carotid bypass was accomplished by drawing blood from the right femoral artery, cooling it to 24 degrees C, and returning it to the right carotid artery at a flow rate of 5 mL/kg/min for 30 minutes.

RESULTS

With initiation of cooling, brain temperatures dropped rapidly from baseline of 37.2 degrees C to 30.6 degrees C (right frontal lobe) and 33.1 degrees C (left frontal lobe) at 30 minutes. Pulmonary artery and rectal temperatures also decreased, but never reached mild hypothermic levels (34 degrees C). There was no significant change in any hemodynamic parameters during brain cooling.

CONCLUSIONS

Femoral-carotid hypothermic bypass rapidly induced a state of selective brain hypothermia without causing systemic hypothermia or hemodynamic instability.

Core rewarming via warm lavage liquid ventilation in a swine model of hypothermia-associated ventricular fibrillation

OBJECTIVES

To determine whether warm lavage liquid ventilation (LV) would provide rapid cardiopulmonary rewarming in swine with severe hypothermia and ventricular fibrillation.

METHODS

Intubated common swine (n = 3; mean +/- SEM weight 26+/-1.2 kg) were cooled to a mean aortic temperature of 26.4+/-0.9 degrees C. Ventricular fibrillation was induced by transthoracic electrical shock. Rewarming was initiated by continuous endotracheal instillation of warm (44 degrees C) pre-oxygenated, perfluorocarbon liquid at 5 mL/kg/min. Endotracheal instillation of perfluorocarbon occurred while standard gas ventilation continued. Manual chest compressions were performed throughout the 30-minute rewarming process. Outcome measures were the absolute and relative rates of change of all temperatures.

RESULTS

After 30 minutes of warm lavage LV, the mean aortic and pulmonary artery temperatures increased by 6.6+/-0.6 degrees C, respectively. Esophageal, nasal, and rectal temperatures did not change significantly. In one animal, normal sinus rhythm spontaneously returned after 16 minutes of rewarming.

CONCLUSIONS

During cardiac arrest, warm lavage liquid ventilation may produce rapid cardiopulmonary rewarming.

"Preconditioning at a distance" in the isolated rabbit heart

OBJECTIVE

Brief myocardial ischemia evokes a cardioprotective response, referred to as "ischemic preconditioning" (IP), that limits injury caused by a subsequent prolonged ischemic insult. The myocardial IP effect can be induced by ischemia of "distant" cardiac and noncardiac tissue, implicating the involvement of an as-yet-unidentified humoral trigger. If a preconditioning hormone exists, the authors hypothesize that the IP effect should be transferable, via administration of coronary effluent, from a preconditioned donor heart to a virgin non-preconditioned acceptor heart.

METHODS

Isolated buffer-perfused rabbit hearts were assigned to one of four treatment groups in a donor/acceptor sequence. Donor hearts underwent either three IP cycles or a matched period of uninterrupted perfusion (control donors). Coronary perfusate collected from IP and control donor hearts was reoxygenated and transfused to virgin acceptor hearts. All hearts then underwent 30 minutes of global ischemia followed by 30 minutes of reperfusion. Left ventricular developed pressure (LVDP) (the authors' index of cardioprotection) was monitored throughout the protocol by a left ventricular (LV) balloon.

RESULTS

In donor controls, LVDP assessed at 30 minutes post-reflow was restored to only 49 +/- 5% of baseline values. Recovery of LV function was significantly enhanced in both IP donor hearts (69 +/- 4%*) and IP acceptor hearts (70 +/- 6%*) vs donor controls (*p < 0.05), while, in acceptor controls, intermediate values of LVDP (62 +/- 7%) were obtained.

CONCLUSION

The IP effect can be transferred between rabbit hearts, suggesting the presence of a humoral trigger signal for distant preconditioning. Isolating this hormone may have therapeutic and diagnostic implications in the management of acute myocardial ischemia.

Ischemic preconditioning may be transferable via whole blood transfusion: preliminary evidence

This research was designed to test the hypothesis that ischemic preconditioning can be transferred between animals via whole blood transfusion. Preconditioning at a distance refers to the reduction in myocardial infarct size seen when coronary artery occlusion is preceded by brief ischemic episodes of noncardiac tissue. Isolation of the trigger signal responsible for this effect may be useful in the diagnosis and treatment of acute coronary occlusive syndromes. Rabbits were paired by crossmatching blood samples prior to experimentation. Crossmatched pairs were placed into either preconditioned (P) or control sets. Rabbits in the preconditioned sets were further divided into donor (PD) and acceptor (PA) animals. PD animals underwent five episodes of circumflex and renal artery occlusion followed by reperfusion. Before and after each preconditioning episode, a whole blood exchange was performed between PD and PA animals. Alternatively, control rabbits underwent the same surgical procedures and time-sequenced transfusion without preconditioning. All animals then underwent prolonged circumflex occlusion (60 minutes) followed by reperfusion (30 minutes). The area of myocardium at risk (R) was determined by isotope-labeled microsphere injection. Infarct size (I) was determined by NBT staining. The percent infarct within the risk area (I/R) was then compared. The I/R was significantly lower in the PA (14.0% +/- 12.2) and PD (14.3% +/- 11.2) groups as compared with controls (61% +/- 20. 6). There was no significant difference between the tPA and TPD groups. In conclusion, the ischemic preconditioning effect can be transferred to nonpreconditioned animals via whole blood transfusion, suggesting a humoral mechanism for preconditioning at a distance.

Ischemic preconditioning may be transferable via whole blood transfusion: preliminary evidence

This research was designed to test the hypothesis that ischemic preconditioning can be transferred between animals via whole blood transfusion. Preconditioning at a distance refers to the reduction in myocardial infarct size seen when coronary artery occlusion is preceded by brief ischemic episodes of noncardiac tissue. Isolation of the trigger signal responsible for this effect may be useful in the diagnosis and treatment of acute coronary occlusive syndromes. Rabbits were paired by crossmatching blood samples prior to experimentation. Crossmatched pairs were placed into either preconditioned (P) or control sets. Rabbits in the preconditioned sets were further divided into donor (PD) and acceptor (PA) animals. PD animals underwent five episodes of circumflex and renal artery occlusion followed by reperfusion. Before and after each preconditioning episode, a whole blood exchange was performed between PD and PA animals. Alternatively, control rabbits underwent the same surgical procedures and time-sequenced transfusion without preconditioning. All animals then underwent prolonged circumflex occlusion (60 minutes) followed by reperfusion (30 minutes). The area of myocardium at risk (R) was determined by isotope-labeled microsphere injection. Infarct size (I) was determined by NBT staining. The percent infarct within the risk area (I/R) was then compared. The I/R was significantly lower in the PA (14.0% +/- 12.2) and PD (14.3% +/- 11.2) groups as compared with controls (61% +/- 20. 6). There was no significant difference between the tPA and TPD groups. In conclusion, the ischemic preconditioning effect can be transferred to nonpreconditioned animals via whole blood transfusion, suggesting a humoral mechanism for preconditioning at a distance.

The use of neuromuscular blocking agents in the emergency department to facilitate tracheal intubation in the trauma patient: help or hindrance?

PURPOSE

The purpose of this study is to examine the relationship between the occurrence of a difficult intubation and (1) the use of neuromuscular blocking agents (NMB) and (2) the presence of airway injuries. It is a retrospective analysis of data from a trauma registry.

MATERIALS AND METHODS

Registry records of patients (n = 160) who required emergent endotracheal intubation or establishment of a surgical airway over a 3.5-year period in the emergency department were reviewed. Risk factors for difficult intubations were identified and analyzed using multivariate logistic regression analysis.

RESULTS

NMB were used in 75% of patients requiring intubation. Fifteen percent of the intubations were considered difficult. No association was found between the presence of airway injuries and difficult intubations; however, the use of succinylcholine was associated with a lower risk of difficult intubations compared with intubations where a nondepolarizing NMB was used.

CONCLUSIONS

The use of succinylcholine may result in fewer difficult intubations in the trauma patient than when a nondepolarizing NMB is used. The presence of airway injuries did not appear to predispose to difficult intubations.

Pulse oximetry is accurate in acute anemia from hemorrhage

HYPOTHESIS

Pulse oximetry is an accurate, noninvasive assay of oxygen saturation percentage (SaO2) in acutely severe anemia (less than 5 g/dL).

DESIGN

A paired comparison of SaO2 by pulse oximetry (SpO2) and arterial blood gas analysis (SaO2) in patients with either acute gastrointestinal bleeding or blunt trauma with hematocrit of less than 20%.

SETTING

An academic emergency department in a tertiary referral hospital with a Level I trauma center.

PARTICIPANTS

Seventeen nonhypoxic patients were identified with initial hematocrit of less than 20% over a 9-month period.

MEASUREMENTS AND MAIN RESULTS

Determination of SaO2 by pulse oximetry and arterial blood analysis was not statistically significantly different (P < .05) over a range of hemoglobin levels from 2.3 to 8.7 g/dL. The observed mean difference between SpO2 and SaO2 was 0.53 +/- 0.23% (mean +/- SEM; n = 17). The 95% confidence interval associated with this difference score ranged from 0.044 to 1.014.

CONCLUSION

Despite reports that pulse oximetry is inaccurate below a hemoglobin concentration of 5 g/dL, our study suggested that this technology is accurate and reliable at 2.3 g/dL for nonhypoxic SaO2 values (SaO2 of more than 93%). The anemic endpoint where pulse oximetry either becomes inaccurate or simply fails to work has not been determined. Pulse oximetry overestimates SaO2 on average by 0.53% over a range of hemoglobin concentrations from 2.3 to 8.7 g/dL.

Evaluation of pulse oximetry in anemia from hemoglobin-H disease

A patient with hemoglobin-H (Hb-H) disease developed an acute hemolytic crisis after treatment with trimethoprim and sulfamethoxazole. Despite her poor clinical condition and profound anemia (Hb, 2.7 g/dL), pulse oximetry continued to demonstrate a high O2 saturation percentage. Manipulation of Beer's law shows that anemia theoretically should not affect pulse oximetry values. The literature describes the effects of dyshemoglobinopathies such as carboxyhemoglobinemia and methemoglobinemia on O2 saturation percentage measured by pulse oximetry, but the effect of genetic hemoglobinopathies on pulse oximetry values is largely unreported. Because most hemoglobinopathies do not significantly change the protein-heme electronic interaction, the values of O2 saturation percentage determined through pulse oximetry should remain clinically valid. Hb-H is an exception to this generalization; as in patients with carboxyhemoglobinemia, pulse oximetry measurements showing high O2 saturation percentage do not correspond to high levels of oxygen available for delivery to tissues.

Concomitant use of activated charcoal and N-acetylcysteine

Activated charcoal is a safe, effective, inexpensive adjunct in the management of most toxic ingestions. It has the ability to adsorb a wide variety of drugs and chemicals, one of which is acetaminophen. N-acetylcysteine (NAC) is the specific antidote available for serious overdoses of acetaminophen. Current management of acetaminophen overdose, however, does not recommend the concomitant oral administration of these two useful agents because adsorption and inactivation of NAC by charcoal is believed to occur. Our study was designed to help evaluate the effect of activated charcoal on N-acetylcysteine absorption. Ten healthy male volunteers were each given in the first, or control, phase of the study an oral dose of 140 mg/kg NAC, and venous blood samples were obtained. In the second phase, after a washout period, each subject received 60 g activated charcoal orally followed immediately by 140 mg/kg NAC. NAC serum levels were measured using gas-liquid chromatography, and levels were compared with and without the concomitant administration of charcoal. Although only a small number of the subjects completed the study, the results showed that in both phases there were no significant differences in the peak NAC levels, the plasma half-life of NAC, or the calculated area under the curve. We recommend that NAC and activated charcoal not be used clinically until further studies are completed.