A new respiratory rate monitor: development and initial clinical experience

The need for continous, noninvasive, and reliable respiratory rate monitoring during recovery from general anesthesia has long been recognized. Alternative principles can be grouped into those detecting the respiratory effort, and those detecting the actual result, i.e. the respiratory gas flow. The second category is of greatest interest for patient monitoring. In this paper, we report the development and initial clinical experience with a new acoustic air-flow sensor. By differential, multipoint detection of the air-flow in the mouth and nose region, the sensor can easily discriminate against different kinds of interference, including motion arterfacts. The sensor is nonexpensive, rugged, simple to apply, and inherently safe. An instrument with continous display of respiratory rate, and an audiovisual apnea alarm has been designed and built.The complete system has been tested on patients during recovery after general anesthesia. In 16 patients, the respiratory rate displayed by the instrument has been correlated against that visually observed. A good correlation was obtained. Minor discrepancies can be explained from the fact that visual observation corresponds to the respiratory effort, whereas the sensor detects the actual air flow. In 12 patients, 24 hour simultaneous recordings were made of respiratory rate with the new sensor, with simultaneous recording of the oxygen saturation and the heart rate with a pulse oximeter. It was found that the new sensor reliabley recorded respiratory depression and apnea. Such events may in some patients be as frequent as one incident per hour. One case of Ondine's curse provided clear evidence that pulse oximetry has a low sensitivity to respiratory disorders.     

Use of a pulse oximeter for determination of systolic blood pressure in a helicopter air ambulance

INTRODUCTION: Traditional methods of determining blood pressure may be unreliable (auscultation or palpation) or unavailable (direct arterial cannulation) in the air medical environment. The authors investigated the combination of a pulse oximeter with a standard sphygmomanometer (blood pressure) cuff as an alternative method. METHOD: The pulse oximeter is applied to a finger on the same upper extremity on which a standard blood pressure cuff had been applied. A baseline blood pressure was obtained by palpation or an automated blood pressure device. One minute later, the systolic blood pressure (SBP) was determined by inflating the blood pressure cuff until the pulsatile display on the pulse oximeter was obliterated. This was taken as the systolic blood pressure. RESULTS: Complete data were obtained on 116 patients, with 223 data pairs. The SBP as obtained by the baseline method was strongly correlated with the SBP obtained by the pulse oximeter display obliteration method (r = 0.90, p < 0.001). CONCLUSION: The obliteration of the wave form display on a pulse oximeter is an accurate, convenient, inexpensive and readily available alternative method of determining SBP.     

The role of carbon dioxide and atmospheric air in double-contrast barium enema

Background Patient discomfort 0–24 h after double-contrast barium enema (DCBE) was investigated in two ways.Methods In part 1, 139 patients, not previously informed, were contacted by telephone to assess symptom rates without bias. In part 2, designed as a prospective randomized double-blind trial, the effect of carbon dioxide (CO₂) as an insufflating gas was compared with conventional atmospheric air (AA).Results Part 1: 10% experienced severe abdominal pain, and 18% severe abdominal distention. Part 2: Low discomfort rates were found for both severe pain (7% for AA vs. 2% for CO₂) and severe distention (13% for AA vs. 8% for CO₂); the differences were not significant. In both parts of the study, female patients with a history of abdominal discomfort of colon irritabile type were significantly overrepresented in the severely symptomatic groups. Equal numbers of patients experiencing severe abdominal distention for the first time were found in both the AA and CO₂ groups, ruling out AA as the sole cause of these symptoms.Conclusion Abdominal post-DCBE discomfort seems to be less frequent than previously reported and is not effectively eliminated by CO₂. We still find the use of AA in DCBEs justified.     

新型导弹驱逐舰舱室大气质量卫生学分析与评价

目的 :舰船作战性及居住性的要求及“全封闭”的环境特点 ,使舱室大气质量的卫生学分析与评价迫在眉睫。方法 :在随舰测定基础上 ,以水面舰艇舱室空气组份容许浓度标准为依据 ;应用人 -机 -环境系统工程理论 ,采用对比方法。结果 :分析归纳了舱室大气污染的主要途径及浓度变化规律 ;提出了舱室大气质量控制建议。结论 :该舰舱室大气质量符合标准。     

Inflammation markers in nasal lavage, and nasal symptoms in relation to relocation to a newly painted building: a longitudinal study

Introduction: There is a need to evaluate possible health effects of ventilation improvements and emissions from new buildings, in longitudinal studies. New methods to study biological effects on the eyes and upper airways are now available. Material and methods: A longitudinal study was performed on 83 trained social workers in two offices in Uppsala, Sweden. The exposed group (n= 57) moved to a newly redecorated building nearby. Low emitting building material had been used, including a new type of solvent-free water-based paint. The control group (n= 26) worked in the same office during the study period (November 1995 to February 1996). Hygiene management was carried out in both offices, at the beginning and the end of the investigation. Tear film stability (BUT) was measured. Nasal patency was measured by acoustic rhinometry, and eosinophilic cationic protein (ECP), myeloperoxidase (MPO), lysozyme and albumin were analyzed in nasal lavage fluid (NAL). Results: The relocation resulted in an increase in the personal outdoor airflow rate from 11 to 22 l/s. Indoor concentrations of terpenes were higher in the new building, and powdering of the new linoleum floor was observed. Measurements showed low levels of volatile organic compounds (VOC), formaldehyde, carbon dioxide (CO₂), nitrogen dioxide, respirable dust, and microorganisms in the air of all buildings. The move resulted in an increased nasal patency and an increase of ECP and lysozyme in NAL, after adjusting for changes in the control group. No changes were observed for nasal or ocular symptoms. A seasonal effect, with a decrease of ECP, was observed in the control group. Conclusion: A well-ventilated office building can be redecorated without any major ocular or nasal effects, or measurable increase of indoor air pollution if low-emitting building materials are selected. In agreement with previous evidence, the improved ventilation flow may explain the increase of nasal patency. The increase of ECP and lysozyme in NAL suggested an inflammatory effect in the new building. Since this building had increased ventilation flow, increased concentrations of terpenes, and powdering from the polish on the new linoleum floor, identification of causative agents was difficult. The hygiene measures did not give any evidence that emissions from the new type of solvent-free water-based paints or building dampness were responsible for the observed nasal effects. Considering the higher emissions of VOC reported from older types of water-based latex paints and solvent-based wall paints, the new type of solvent-free water-based paint seems to be a good choice from the hygiene point of view. Received: 21 December 1998 / Accepted: 20 June 1999     

常见大气细菌对动物肺损伤的实验研究

为研究大气微生物对人体健康的影响,于１９９７年对上海市大气细菌污染进行了调查。在此基础上,采用大鼠经气管灌注细菌悬液２４小时后,分析肺灌洗液组成的方法,就大气细菌对动物呼吸系统损伤方面进行了研究。同时比较了不同地区大气细菌对大鼠肺细胞的损伤效应。结果发现大气细菌污染严重地区的细菌染毒组ＡＬＢ、ＬＤＨ、ＡＣＰ、ＡＫＰ、中性粒细胞等指标比清洁区升高更为显著,提示大气中常见细菌可对肺组织造成损伤。     

A new surgical technique for deep stromal, anterior lamellar keratoplasty

AIMS: To describe a new surgical technique for deep stromal anterior lamellar keratoplasty. METHODS: In eye bank eyes and sighted human eyes, aqueous was exchanged by air, to visualise the posterior corneal surface--that is, the "air to endothelium" interface. Through a 5.0 mm scleral incision, a deep stromal pocket was created across the cornea, using the air to endothelium interface as a reference plane for dissection depth. The pocket was filled with viscoelastic, and an anterior corneal lamella was excised. A full thickness donor button was sutured into the recipient bed after stripping its Descemet's membrane. RESULTS: In 25 consecutive human eye bank eyes, a 12% microperforation rate was found. Corneal dissection depth averaged 95.4% (SD 2.7%). Six patient eyes had uneventful surgeries; in a seventh eye, perforation of the lamellar bed occurred. All transplants cleared. Central pachymetry ranged from 0.62 to 0.73 mm. CONCLUSION: With this technique a deep stromal anterior lamellar keratoplasty can be performed with the donor to recipient interface just anterior to the posterior corneal surface. The technique has the advantage that the dissection can be completed in the event of inadvertent microperforation, or that the procedure can be aborted to perform a planned penetrating keratoplasty.     

Multiple chemical sensitivities: an overview

At the present time multiple chemical sensitivities (MCS) is generally acknowledged to be a poorly understood clinical syndrome which is exhibited by individuals exposed to low levels of exposure to environmental agents that the general population tolerate quite well. A wide range of individual symptoms (typically multiple and related to neurologic, endocrine/metabolic, and immunological, often occurring simultaneously) are displayed by MCS patients. Questions concerning whether or not MCS is a real clinical condition, a form of psychiatric illness or a combination of both remain to be unambiguously clarified.     

A comparison of pediatric and adult trauma patients transported by helicopter and ground EMS: managed-care considerations

INTRODUCTION: There is a paucity of data comparing injured pediatric patients transported by helicopter emergency medical services (HEMS) with patients transported by ground ambulance. The purpose of this study was to compare HEMS pediatric trauma patients to: 1) pediatric patients transported by ground to an urban level-1 trauma center (TC), and; 2) a similar cohort of adult patients. The managed-care consequences of these comparisons are highlighted. METHODS: All trauma patients flown directly from the scene by HEMS from January 1, 1990, to April 30, 1993, were compared to a cohort of trauma patients arriving by ground advanced life support (ALS). All patients were transported to the same level-1 TC. The data collected included the mechanism of injury and the prehospital procedures performed, the injury severity score (ISS), and outcome. RESULTS: There was no difference in the ISS between the HEMS (n = 216) and ground ALS (n = 355) pediatric patients (16.8 vs 17.1; p = 0.55). Adult HEMS patients (n = 202) had significantly higher ISS than did injured adults (n = 1652) transported by ground (18.0 vs 13.6; p < 0.0001). Overall, trauma patients transported by air directly from the scene have a higher ISS than patients transported by ground (17.5 vs 13.6; p < 0.001). CONCLUSIONS: Pediatric patients transported by HEMS were as severely injured as those transported by ground, in contrast to adult patients. We conjecture that since trauma triage schemes classically focus on adults, ground personnel are more selective about which patients are flown to a TC, and less selective for pediatric patients. Trauma centers and HEMS programs should develop pediatric trauma triage protocols that do not overemphasize physiologic parameters.     

Exposure to soluble barium compounds: an interventional study in arc welders

Summary Soluble barium (Ba) compounds are well-known toxicants. Intoxications are mainly known in an acute form from casual or suicidal oral ingestion. No scientifically based data are available on possible health effects of inhalative exposure to soluble Ba salts at the workplace. Therefore, we investigated 18 welders in an interventional study over 1 week. They performed welding of Ba-containing stick electrodes and self-shielded flux cored wires under conditions similar to real working conditions. The welding fumes contained 31%–37% Ba, more than 90% of which was soluble in acids. Without appropriate preventive measures, a high rate of measurements exceeded the TLV values for total welding fumes of 5 mg/m³ and for soluble Ba of 0.5 mg/m³. The median fume concentrations were 13.2 mg/m³ in stick electrode welding and 12.3 mg/m³ in flux cored wire welding. The median Ba concentrations were 4.4 and 2.0 mg/m³ respectively. An integrated exhaust system built into the gun proved to be efficient in flux cored wire welding. The internal exposure to Ba reached median urine levels up to 101.7 g/l (normal: below 20 g/l) and median plasma concentrations of up to 24.7 g/l (normal: below 8 g/l). No health impact on the welders could be proven, but hypokalemia may have occurred as a result of the Ba exposure.