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Biomedical subjects

R D Stewart

Publications and source records attributed to R D Stewart.

At least 55 records · Page 3Linked to original sources
PubMed1989

Advances in prehospital immediate care.

Although studies documenting the influence of prehospital care on patient outcome are most urgently needed, recent techniques and innovations being examined in the field setting may improve the clinical care delivered. The basic manoeuvres for airway and breathing have been in need of emphasis for some time. Sellick's manoeuvre has been resuscitated and is being emphasized in most training programmes. Bag-mask ventilation, notoriously difficult in field settings in the hands of emergency medical personnel, has been improved with the recent improvement of mask design. Endotracheal intubation has been shown to influence patient outcome, and can be performed with surprising success by paramedics. Complication rates continue to cause concern, and a study to document the incidence of tube misplacement has just begun in the United States and Canada. Transillumination and translaryngeal jet ventilation have been refined as adjunct techniques to field intubation. Patient monitoring has improved through the more common use of pulse oximetry and a recently-introduced "CO2 Detector" that is designed to indicate via a colour change, oesophageal placement of an endotracheal tube. Automatic external defibrillators have come under some scrutiny, and early data suggest their safe use by lay persons, a minimal effect on outcome in high-risk patients, and a significant effect on outcome only when combined with other essential elements of prehospital care. The role of IV fluids in prehospital trauma care has been clarified, as well as that of the pneumatic antishock garment. Transcutaneous pacemakers have been developed and shown effective if used early, and thrombolytic therapy has been examined for the prehospital management of acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergency Medical Services↗
PubMed1989

Pulse oximetry in the emergency department.

Three cases representing the emergency department use of pulse oximetry are described. A brief review of the principles of operation of pulse oximetry, as well as a discussion of recent literature and clinical uses of the technology, is presented. While not replacing arterial blood gases in the assessment of critically ill patients, a more widespread use of pulse oximetry in evaluating emergency department patients might provide significant information in the management of patients with respiratory complaints. Pulse oximetry may also play an important role in monitoring those patients requiring airway interventions such as assisted ventilation or endotracheal intubation.

Adolescent↗
PubMed1989

Emergency department telephone advice.

Emergency department personnel are frequently asked to give advice to members of the community who telephone for advice or information about a wide variety of medical problems. A study was designed to determine the consistency and accuracy of directions given to adults who call EDs seeking advice about a problem. Forty-six EDs were selected and telephoned for advice by a research assistant who presented a scenario that could have reasonably been interpreted as a patient experiencing myocardial ischemia. Nine percent of the calls were answered and managed only by ED unit secretaries. Fifty-six percent of the respondents failed to ask the caller any questions about the patient or the chief complaint. Only four ED respondents instructed the caller to call 911 and have the patient brought to the ED. The data suggest that telephone advice given by some EDs is nonstandardized and may be inadequate to the point of jeopardizing the welfare of the caller.

Adult↗
PubMed1989

Manual translaryngeal jet ventilation.

The manual translaryngeal jet technique is a safe and reliable method of emergency ventilation, providing adequate gas exchange and high levels of oxygenation for the patient who requires positive pressure breathing. It can be performed more rapidly than other invasive means of airway control and, with close attention to the proper technique, has proved safe and effective in maintaining normal blood gases for prolonged periods. Further work is required to define proper inspiratory-to-expiratory ratios better and to determine whether the technique is protective against aspiration. The equipment and technique should be familiar and readily available to every emergency clinician.

Emergencies↗
PubMed1988

Abdominal aortic aneurysm.

Between 1981 and 1986, 282 cases of abdominal aortic aneurysm were diagnosed in Waltham Forest. Rupture had occurred in 183, 15 underwent urgent operation for intact aneurysm, and 84 had elective surgery. The incidence of rupture increased from 13 to 21 per 100,000 population during the 6-year period. Operative mortality for patients with rupture was 54.7 per cent, but the mortality overall was 81.4 per cent. In 59 per cent of patients with rupture no operation was performed, and 35.0 per cent of all deaths occurred in the community. The mortality for rupture in women was significantly higher than in men, although the operative mortality was comparable. Fifty patients (27 per cent) were found to have attended hospital within 2 years of rupture and many had documented evidence of an aneurysm. One-third of all patients admitted with rupture were undiagnosed. This study complements the previous small number of community studies and suggests that the incidence of rupture is increasing nationally particularly in women, where the mortality was exceptionally high. Early elective surgery is the key to the problem and improved clinical awareness could save many patients without elaborate and expensive programmes to screen the 'at risk' population.

Age Factors↗
PubMed1988

Oxygen enrichment of bag-valve-mask units during positive-pressure ventilation: a comparison of various techniques.

Bag-mask devices are used frequently to provide patients with positive-pressure-assisted ventilation. To increase the percentage of oxygen delivered (FDO2) from the bag, supplemental oxygen must be provided by way of an oxygen inlet nipple attached to the unit. Using ten medical volunteers and a test lung with oxygen analyzer, we studied the effect of several variables on the FDO2 and determined the most effective reservoir that would provide the highest consistent FDO2 from the ventilating port of the bag. An FDO2 of 1.00 was consistently provided by the 2.5-L bag reservoir and a demand-valve set-up attached to the reservoir port of the ventilating bag. Bag refill time significantly affected the FDO2 when no reservoir or corrugated tube reservoirs were used. Corrugated tube reservoirs were found to be more sensitive to all variations in ventilatory technique and to oxygen flow rates. From our findings we recommend that corrugated tube reservoirs not be used for oxygen supplementation, as they are sensitive to variations in ventilatory technique and cannot alert clinicians to problems with oxygen flow. While both the 2.5-L bag reservoir and demand-valve provide a consistent FDO2 of 1.00, the demand valve has the advantage of audible filling of the ventilating bag as well as being compact and independent of ventilatory technique.

Equipment Design↗
PubMed1988

Tracheitis: the 'other' cause of upper airway obstruction.

A 22-year-old woman presented to an ear, nose, and throat clinic with an upper respiratory infection and sudden stridorous respirations. Aerosolized isoethrane therapy was beneficial and fiber-optic nasolaryngoscopy revealed a normal supraglottis and purulent intratracheal secretions. Secretions were cultured and grew Staphylococcus aureus and alpha hemolytic Streptococcus. IV cefazolin was initiated and the patient recovered without sequelae. This case illustrates a rare cause of upper airway obstruction, tracheitis. Tracheitis has been found in the pediatric literature. This is the first adult case reported in the literature.

Adult↗
PubMed1988

Myths and pitfalls in emergency translaryngeal ventilation: correcting misimpressions.

Translaryngeal jet ventilation has been proven an effective emergency airway alternative. However, confusion exists as to the proper cannulae and oxygen sources for this technique. Our study was designed to determine the delivered volumes of gas using cannulae and oxygen sources recommended in previous reports on translaryngeal jet ventilation. From this, we hope to clarify the proper technique of translaryngeal jet ventilation. Using a variety of oxygen sources and cannulae, peak flow rates were measured using a digital flowmeter. Delivered volumes of gases generated with each combination were then calculated. All of the cannulae tested (standard 16-gauge IV cannulae and larger) provided peak flow rates high enough so that predicted tidal volumes would be adequate to maintain adequate ventilation in apneic adults when a 50-psi source was used. Only a 4-mm tracheal cannula provided comparable values when a bag-valve device was used. No cannulae provided sufficient flow rates to ensure adequate ventilation in apneic adults when a demand-valve mechanism of 60 cm H2O driving pressure served as the source. Our observations were consistent with previous clinical studies and suggest that standard translaryngeal jet ventilation cannulae (12 to 16 gauge) must be connected to an oxygen source of 50 psi in apneic adults. Demand-valve devices do not provide sufficient driving pressures for these cannulae. A cannula of 4 mm ID should be placed if only a bag-valve device is available for ventilation.

Apnea↗
PubMed1987

Design of a resident in-field experience for an emergency medicine residency curriculum.

The importance of a resident training in emergency medical services (EMS) is emphasized by the recent development of formal curricula that attempt to prepare the graduating emergency physician for a leadership role in the EMS community. Despite the delineation of specific goals and objectives of such training, actual field exposure and experience in prehospital care have remained voluntary and often sporadic. We designed a resident experience for on-scene attendance at selected incidents and surveyed our residents for their opinion of the curriculum. We also examined field records to determine the nature of field calls and the numbers and types of procedures carried out by second- and third-year residents. During the six-month review period, 158 cardiac arrests were attended, 58 difficult intubations were carried out, 49 central or peripheral lines were started, and 24 severely injured patients were treated on-scene or en route to the hospital. The average response time by the resident to the scene was nine minutes, and the average on-scene time was 20 minutes. Residents completing the survey indicated support for the program and agreed that it has enriched their learning experience. Combined with an air (helicopter and fixed-wing) and ground critical care transport service, the EMS in-field experience has provided opportunities for residents to make rapid decisions, to appreciate the field team's perspective, to report concisely and clearly to colleagues, and to practice required advanced skills. We believe that a formal, planned, and balanced in-field curriculum can afford an opportunity for unique educational experiences that will enrich the graduate program in emergency medicine.

Curriculum↗
PubMed1987

Methemoglobin levels following intravenous lidocaine administration.

Methemoglobin levels were obtained before and after administration of IV lidocaine in 40 cardiac patients. Patients were given a 1-mg/kg bolus of IV lidocaine hydrochloride, started on a maintenance infusion at 2.0 mg/min, and given a second bolus of lidocaine of 0.5 mg/kg 15 minutes after the initial bolus. The maintenance infusion was adjusted from 1 to 4 mg/min according to clinical needs. Methemoglobin levels were drawn at zero, one, and six hours, and lidocaine levels were drawn at one and six hours after the initial bolus. Elevation of methemoglobin levels after lidocaine administration was statistically significant (P less than .05), but not clinically significant. The highest methemoglobin level obtained was 1.2%. Only one other patient had a level above 1%. No patient developed either signs of lidocaine toxicity or toxic levels of methemoglobin. Routine determination of methemoglobin levels is not clinically indicated following routine lidocaine administration. It may have some as-yet-undetermined value in lidocaine-toxic patients.

Adult↗
PubMed1987

Effect on the seizure threshold in dogs of tocainide/lidocaine administration.

Oral lidocaine analogues, such as tocainide, recently have been introduced to treat cardiac arrhythmias. The side effects of tocainide are similar to those of lidocaine, but possible interactions with lidocaine have not been examined thoroughly. With the increased use of these agents, emergency physicians must decide the safety of concurrent administration of lidocaine for local anesthesia or arrhythmia management. Twelve dogs were assigned randomly to either a lidocaine (L) or a tocainide/lidocaine (TL) group. The L group received lidocaine at a dosage of 0.5 mg/kg/min until the animals seized. The TL group received both loading and maintenance doses of tocainide to obtain therapeutic steady-state tocainide levels prior to receiving lidocaine at a dosage of 0.5 mg/kg/min. Venous blood samples to measure drug levels were obtained at 20-minute intervals and at the time of seizures. The average duration of lidocaine administration required to induce seizures in the L group was 70.0 +/- 7.5 minutes, and in the TL group 29.0 +/- 7.0 minutes (P less than .05). In addition, the average serum lidocaine level at the time of seizures was 11.2 +/- 1.0 micrograms/mL in the L group and 6.2 +/- 1.7 micrograms/mL in the TL group (P less than .05). Our results show that in animals the presence of a therapeutic serum level of tocainide lowers the seizure threshold following the administration of lidocaine. These findings may have important implications for clinical care because they suggest that lidocaine should be used cautiously and in reduced dosage in patients already taking tocainide.

Animals↗