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Biomedical subjects

H E Wang

Publications and source records attributed to H E Wang.

24 records · Page 2Linked to original sources
PubMed1986

Olfactory evoked potentials in the rat.

Routine clinical assessment of the integrity of the olfactory pathway using olfactory evoked potentials remains an elusive goal. One important difficulty arises from the uncertainty of the exact origin of the potentials: are they produced by olfactory or trigeminal elements? To resolve this problem, an animal model using the rat was developed. Amylacetate was used as an odorant stimulus, and potentials were measured and computer averaged after elimination of trigeminal and vomeronasal activity. A positive-negative wave was recorded from the olfactory bulb surface, and a negative wave often followed by a positive wave was recorded from the surface of the cerebral cortex. Measurements from the scalp surface gave comparable results. Lesioning experiments of the olfactory pathway indicate that the evoked potentials recorded at the vertex originate in the ventral forebrain, specifically in the prepyriform cortex, olfactory tubercle, and anterior olfactory nucleus.

Animals↗
PubMedDate not supplied

Subclavian central venous catheterization complicated by guidewire looping and entrapment.

The placement of central venous catheters is a technically challenging procedure with known risks and complications. We report an attempted left subclavian central venous catheterization that was complicated by looping and entrapment of the guidewire. We hypothesize that this complication occurred because the straight guidewire that was used may have perforated the wall of the vein, allowing the guidewire to loop upon itself. Although catheter looping and knotting are well known potential complications of central venous catheterization, similar complications are rarely reported with guidewires. Clinicians should be aware of these potential complications when performing or teaching central venous catheterization.

Catheterization, Central Venous↗
PubMedDate not supplied

The utilization of midazolam as a pharmacologic adjunct to endotracheal intubation by paramedics.

OBJECTIVE: Pharmacologic agents have been used in the prehospital setting for facilitating endotracheal intubation (ETI). The purpose of this study was to determine the utility of intravenous midazolam for prehospital patients who require pharmacologic relaxation to facilitate ETI. METHODS: Data were reviewed retrospectively using paramedic charts from an eight-month period for a three-county state EMS system. RESULTS: There were 26,133 paramedic dispatches during the study period. Six hundred eighty-three ETIs were attempted, including 72 midazolam-facilitated intubations (MFIs). The most common indications for MFI were "clenched teeth," "gag," and "combativeness." Successful MFI was achieved in 45 of 72 cases (62.5%). Midazolam-facilitated intubation was less successful for trauma patients (41.2%) than for medical patients (69.1 %) (p = 0.04). Of the 58 failed conventional ETIs that occurred during the study period, 25 (43.1%) were identified as having one or more indications for the use of MFI. Although the use of intravenous midazolam was effective in facilitating ETI, a high MFI failure rate (37.5%) was noted. CONCLUSION: Although it is of limited efficacy, MFI is underutilized and should be considered by medical direction as a pharmacologic adjunct to ETI in selected field patients.

Delaware↗
PubMedDate not supplied

Failed prehospital intubations: an analysis of emergency department courses and outcomes.

OBJECTIVE: To examine the reasons for failed prehospital endotracheal intubation (ETI) and to identify how the airway was subsequently managed in the emergency department (ED). METHODS: Data were collected from January to December 1998 for a county-wide paramedic system. Failed prehospital ETIs and perceived reasons for failure were identified. Subsequent ED airway management was reviewed. RESULTS: During the study period there were 13,112 patient contacts resulting in ETI attempts on 592 patients, of whom 536 (90.5%) were successfully intubated. Of the 56 failed field intubations, 49 (87.5%) had ED charts available for review. Endotracheal intubation failure was associated with inadequate relaxation in 24 (49%), difficult anatomy in ten (20%), and obstruction in five (10%). Successful ETI was achieved in the ED in 42 cases (86%). Twenty cases (41%) were facilitated by rapid-sequence intubation (RSI) in the ED. For those with incomplete relaxation in the field, 13 of 24 (54%) were intubated in the ED using RSI. Factors associated with the use of ED RSI include attempted prehospital nasotracheal intubation or attempted prehospital midazolam-facilitated intubation (p < 0.001). The predicted need for RSI in this prehospital system is approximately 3.9%. In eight cases, three or more ETI attempts or the use of rescue airways was required in the ED. The predicted minimum incidence of "truly difficult" intubation in this system is approximately 0.8-1.6%. CONCLUSIONS: Paramedic intubation failures result from a variety of factors. Less than half of field intubation failures were remedied in the ED by the use of neuromuscular-blocking agents. A similar number were intubated without the use of RSI. A fraction of failed field ETIs may have resulted from inadequate operator training or experience. A small percentage of field patients were "truly difficult" and required advanced resources in the ED to facilitate airway management. Medical directors should be cognizant of the numerous factors affecting intubation performance when designing and implementing approaches to difficult prehospital airways.

Adolescent↗
PubMedDate not supplied

Patient status and time to intubation in the assessment of prehospital intubation performance.

UNLABELLED: Assessment of paramedic endotracheal intubation (ETI) performance often does not account for varied clinical conditions or the time required to complete the procedure. OBJECTIVE: To demonstrate the utility of patient status and time to intubation (TTI) for evaluating prehospital ETI performance. METHODS: Paramedic charts were reviewed for the period January-December 1998. Patient clinical status was defined as cardiac arrest (absence of perfusing rhythm) or non-cardiac arrest (presence of perfusing rhythm). Method, route, and success of ETI were noted. The TTI was determined as the elapsed time from on-scene arrival to securing of the endotracheal tube. Time elapsed from on-scene arrival to emergency department arrival was noted for instances of failed ETI. Statistical analysis was performed using chi-square and survival analysis (Kaplan-Meier estimator). RESULTS: Computer records were available for 26,026 patient contacts. Of 893 documented ETI attempts, 771 (86%) were successful. The ETI success rate was significantly higher (p<0.001) for cardiac arrests (551 of 591, 93.2%) than for non-cardiac arrests (220 of 302, 72.9%). Median TTIs were 5 minutes (95% CI: 5, 5) for cardiac arrests and 17 minutes (95% CI: 14, 20) for non-cardiac arrests; this difference was significant (p<0.001). For non-cardiac arrests, ETI success was significantly (p = 0.002) higher for orotracheal intubation (OTI) (168 of 214, 78.5%) than for nasotracheal intubation (NTI) (52 of 88, 59.1%). Median TTIs were 15 minutes (95% CI: 13, 17) for OTI and 25 minutes (95% CI: 23, 27) for NTI; this difference was significant (p = 0.002). For non-cardiac arrests, the difference i

Delaware↗