Erreur de branchement d'un flexible d'air médical sur une prise de protoxyde d'azote par défaillance du système détrompeur

When plugging the O₂, N₂O and air hoses into the corresponding wall sockets, the air hose was wrongly inserted into the N₂O wall outlet. This was made possible because of faulty retaining clasps of the male coupler of the air probe. French “fail-safe” connections consist of a two-clasp male coupler for air, three clasps for O₂ and four clasps for N₂O hoses. Additionally the clasps of the air probe are broader then those of the N₂O probe. However, the latter difference was lost due to wear. The incident was recognized without delay as the N₂O hose could not be inserted into the air outlet. However, it could have remained unnoticed had there been two N₂O wall outlets and could have resulted in severe adverse effects.     

Editorial Commentary: Just Getting Warmed Up: Risks,Benefits, and Economics of Active Warming Devices

Efforts to maintain normothermia should be a part of every patient’s perioperative care. Risks, benefits, and economic implications should be considered when deciding how to use active warming devices for orthopaedic surgery. The Centers for Medicare & Medicaid Services has implemented economic incentives and penalties driving hospitals to invest in active warming devices, including forced-air warmers and resistive heating devices. Even though forced-air warmers and resistive heating blankets are likely to statistically improve patient temperatures, they may not be worth the additional cost for shorter, less invasive, elective arthroscopic surgeries. In addition, recent research demonstrates minimal clinically significant differences between these 2 types of devices. Concern regarding possible increased risk of surgical-site contamination with forced-air warmers warrants further study but, again, is unlikely clinically relevant to arthroscopic cases, and proper staff training and warming equipment routine maintenance could minimize patient risk.     

Damage control surgery and perioperative management

In damage control surgery, not only successful surgical procedures but also general management are crucial. Specifically, body temperature maintenance and aortic occlusion are major strategies supporting damage control surgery. Strategies for maintaining body temperature should be initiated at the scene of the incident by prehospital care providers. Radiant warmers should be installed in the ceilings of emergency rooms, and powerful warmers for fluids and blood, e.g., System 1000, should be utilized. Water blankets and the Bear Hugger system are also effective in maintaining patient body temperature. We have been successful in avoiding decreases in temperature during laparotomy using a combination of those strategies. In cases of massive hemoperitoneum aortic occlusion prior to abdominal incision is recommended to avoid cardiac arrest. We developed an intraaortic balloon occluder (Block Balloon) and inserted it in 26 patients undergoing damage control surgery. Ten patients survived, for a survival rate of 61.5%.     

Comparison of forced-air warming systems with lower body blankets using a copper manikin of the human body

Background: Forced‐air warming has gained high acceptance as a measure for the prevention of intraoperative hypothermia. However, data on heat transfer with lower body blankets are not yet available. This study was conducted to determine the heat transfer efficacy of six complete lower body warming systems. Methods: Heat transfer of forced‐air warmers can be described as follows: Q˙=h·ΔT·A ([1]) where Q˙ = heat transfer [W], h = heat exchange coefficient [W m^?2 °C^?1], ΔT = temperature gradient between blanket and surface [°C], A = covered area [m²]. We tested the following forced‐air warmers in a previously validated copper manikin of the human body: ( 1 ) Bair Hugger^® and lower body blanket (Augustine Medical Inc., Eden Prairie, MN); ( 2 ) Thermacare^® and lower body blanket (Gaymar Industries, Orchard Park, NY); ( 3 ) WarmAir^® and lower body blanket (Cincinnati Sub‐Zero Products, Cincinnati, OH); ( 4 ) Warm‐Gard^® and lower body blanket (Luis Gibeck AB, Upplands Väsby, Sweden); ( 5 ) Warm‐Gard^® and reusable lower body blanket (Luis Gibeck AB); and ( 6 ) WarmTouch^® and lower body blanket (Mallinckrodt Medical Inc., St. Luis, MO). Heat flux and surface temperature were measured with 16 calibrated heat flux transducers. Blanket temperature was measured using 16 thermocouples. ΔT was varied between ?10 and +10 °C and h was determined by a linear regression analysis as the slope of ΔT vs. heat flux. Mean ΔT was determined for surface temperatures between 36 and 38 °C, because similar mean skin temperatures have been found in volunteers. The area covered by the blankets was estimated to be 0.54 m². Results: Heat transfer from the blanket to the manikin was different for surface temperatures between 36 °C and 38 °C. At a surface temperature of 36 °C the heat transfer was higher (between 13.4 W to 18.3 W) than at surface temperatures of 38 °C (8–11.5 W). The highest heat transfer was delivered by the Thermacare^® system (8.3–18.3 W), the lowest heat transfer was delivered by the Warm‐Gard^® system with the single use blanket (8–13.4 W). The heat exchange coefficient varied between 12.5 W m^?2°C^?1 and 30.8 W m^?2°C^?1, mean ΔT varied between 1.04 °C and 2.48 °C for surface temperatures of 36 °C and between 0.50 °C and 1.63 °C for surface temperatures of 38 °C. Conclusion: No relevant differences in heat transfer of lower body blankets were found between the different forced‐air warming systems tested. Heat transfer was lower than heat transfer by upper body blankets tested in a previous study. However, forced‐air warming systems with lower body blankets are still more effective than forced‐air warming systems with upper body blankets in the prevention of perioperative hypothermia, because they cover a larger area of the body surface.     

Klimatisierung von Narkosegasen bei Einsatz unterschiedlicher Patientenschlauchsysteme

Background. During general anaesthesia gas climate significantly is improved by performance of low flow techniques. Gas climatisation, however, markedly also will be influenced by the temperature loss at, and corresponding water condensation within the hoses, factors which are related to the technical design and material of the patient hose system. The objective of this prospective study was to investigate 1. how anaesthetic gas climatisation during minimal flow anaesthesia is influenced by the technical design of different breathing hose systems in clinical practice. 2. to investigate, whether a sufficient gas climatisation also can be gained with higher fresh gas flows if that hose system is used, proven beforehand to optimally warming and humidifying the anaesthetic gases. Methods. Three different systems, a conventional two-limb hosing consisting of smooth silicone hoses, a coaxial hosing, and a hosing consisting of actively heated breathing hoses, attached to a Dräger Cicero EM anaesthesia machine, were used during minimal flow anaesthesia with a fresh gas flow of 0.5 l/min. Gas temperature and absolute humidity were measured at the tapered connection between the inspiratory limb and the breathing system as well as at its connection to the endotracheal tube. The best gas climatisation was observed if heated breathing hoses were used. Thus, using this hosing, additionally gas temperature and humidity in the inspiratory limb were taken at fresh gas flow rates of 1.0, 2.0 and 4.4 l/min respectively. Measurements were performed in all groups at all general anaesthesias lasting at least 45 minutes during the lists of eight different days each. Results. In minimal flow anaesthesia, with all hose systems likewise, generally an absolute humidity between 17 to 30 mgH₂O/l is reached at the endotracheal tube's connector during the course of the list. Only in the first cases of the day there was a short delay of 15 to 30 minutes before reaching a humidity of at least 17 mgH₂O/l. Only with heated hoses, however, humidity frequently even exceeded 30 mgH₂O/l. If conventional or coaxial hosings were used, during minimal flow anaesthesia gas temperatures in an acceptable range between 23 to 30 °C were measured at the tube connector. With heated hoses, however, warming of the gases was excellent with gas temperatures betwen 28 to 32 °C. In minimal flow anaesthesia climatisation of the anaesthetic gases proved to be best if heated hoses were used. Thus, using heated hose systems another three trials with increasing fresh gas flow rates of 1.0, 2.0 and 4.4 l/min respectively were performed. Whereas climatisation of the anaesthetic gases still was found to be optimal with a fresh gas flow of 1.0 l/min, the humidity dropped drastically to values lower than 17 mgH₂O/l at 2.0 l/min and even down to 10 mgH₂O/l at a flow rate of 4.4 l/min. Gas temperatures, however, turned out to be independent of the flow and remained at 28–32°C, even at a flow as high as 4.4 l/min. Conclusions. Using conventional hose systems and coaxial hosings acceptable, but not optimal climatisation of the anaesthetic gases can be gained if minimal flow anaesthesia is performed. The use of a coaxial hose system seems to lead to improved climatisation in long lasting procedures only. In routine clinical practice, however, conventional and coaxial hose systems are similar in respect to the climatisation of breathing gases. Heated breathing hoses performed markedly better in terms of climatisation of the breathing gas than the coaxial and the conventional hose system. With this hosing not only sufficient but optimal moisture and temperature values are realized. Optimal climatisation, however, only can be gained if low flow anesthetic techniques with fresh gas flows equal or less than 1 l/min are performed. With higher fresh gas flow rates the humidity decreases markedly while high gas temperatures are maintained. It seems justified to assume, that ventilation with warm but dry gases may result in increasingly drying out of the respiratory epithelium of the lower air ways. Heated hoses only should be used if low flow anaesthetic techniques are performed. While moisture content of the breathing gases mainly is influenced by the fresh gas flow rate, temperature mainly is depending on the convectional loss of heat at the inspiratory limb of the hosing.     

Randomized prospective comparison of forced air warming using hospital blankets versus commercial blankets in surgical patients

BACKGROUND: The purpose of this study was to evaluate the efficacy of an experimental approach to forced air warming using hospital blankets or a Bair Hugger warming unit (Augustine Medical Inc., Eden Prairie, MN) to create a tent of warm air. METHODS: Adult patients undergoing major surgery were studied. Patients were randomized to receive forced air warming using either a commercial Bair Hugger blanket (control group, n = 44; set point, 43 degrees C) or standard hospital blankets (experimental group, n = 39; set point, 38 degrees C). Distal esophageal temperatures were monitored. Patients were contacted the following day regarding any problems with the assigned warming technique. RESULTS: Surface area covered was 36 +/- 12% (mean +/- SD) in the experimental group and 40 +/- 10% in the control group. Final temperatures at the end of surgery were similar between groups: experimental, 36.2 +/- 0.6 degrees C; control, 36.4 +/- 0.7 degrees C. A similar number of patients had esophageal temperature less than 36 degrees C at the end of surgery in both groups (experimental, 12 of 39 [31%]; control, 12 of 44 [27%]). The majority of patients were satisfied with their anesthetic and warming technique: experimental, 38 of 39 patients; control, 44 of 44 patients. There were no thermal injuries. CONCLUSIONS: Standard hospital blankets heated to 38 degrees C forced air were equally as effective as commercial blankets heated with forced air at 43 degrees C. However, based on concerns expressed by the manufacturer, this experimental technique should not be used until further safety evaluation has been undertaken.     

Transfusion massive : analyse des pratiques en fonction des dispositifs médicaux disponibles

Introduction

An assessment of practices and available medical devices during the treatment of a massive haemorrhage has been realised in the shock unit of our hospital.

Material and methods

Parameters influencing transfusion flow rate have been identified. Medical devices and equipment to accelerate the flow rate were analyzed on the basis of manufacturers’ data and users opinion in relation with their practices.

Results

The system, from blood bags to venous access, influences flow rate: red blood cell viscosity, catheter and pressure gradient. Three types of acceleration systems are available: accelerated transfusion set, pressure cuff with a gravity blood IV set and fast-flow fluid warmers. Their benefits and disadvantages are presented and discussed.

Discussion

Maximum flow rates noted by manufacturers are not the real values because some parameters such as venous catheter diameter (limitative factor) and the red blood cell viscosity (diluted or not) are not considered. The choice of an infusion system is mainly based on the technical capacities (flow rate fluctuations, pressure gradient on blood bags, warming, air purging), practical modalities of use (medical devices and assembly) and cost. The pressure cuff with transfusion gravity set should be limited to non-critical situations or during the assembly of the fast flow fluid warmers (but no warming fluids, no air embolism prevention). The accelerated transfusion set is not the best option for a shock unit because it needs an operator permanently. The fast-flow fluid warmers are recommended for all types of massive haemorrhages, they are more secure but they require a long time to be assembled.     

Comparison of forced-air warming systems with upper body blankets using a copper manikin of the human body

Background: Forced‐air warming with upper body blankets has gained high acceptance as a measure for the prevention of intraoperative hypothermia. However, data on heat transfer with upper body blankets are not yet available. This study was conducted to determine the heat transfer efficacy of eight complete upper body warming systems and to gain more insight into the principles of forced‐air warming. Methods: Heat transfer of forced‐air warmers can be described as follows: Q˙=h · ΔT · A, where Q˙= heat flux [W], h=heat exchange coefficient [W m^?2 °C^?1], ΔT=temperature gradient between the blanket and surface [°C], and A=covered area [m²]. We tested eight different forced‐air warming systems: (1) Bair Hugger^® and upper body blanket (Augustine Medical Inc. Eden Prairie, MN); (2) Thermacare^® and upper body blanket (Gaymar Industries, Orchard Park, NY); (3) Thermacare^® (Gaymar Industries) with reusable Optisan^® upper body blanket (Willy Rüsch AG, Kernen, Germany); (4) WarmAir^® and upper body blanket (Cincinnati Sub‐Zero Products, Cincinnati, OH); (5) Warm‐Gard^® and single use upper body blanket (Luis Gibeck AB, Upplands Väsby, Sweden); (6) Warm‐Gard^® and reusable upper body blanket (Luis Gibeck AB); (7) WarmTouch^® and CareDrape^® upper body blanket (Mallinckrodt Medical Inc., St. Luis, MO); and (8) WarmTouch^® and reusable MultiCover? upper body blanket (Mallinckrodt Medical Inc.) on a previously validated copper manikin of the human body. Heat flux and surface temperature were measured with 11 calibrated heat flux transducers. Blanket temperature was measured using 11 thermocouples. The temperature gradient between the blanket and surface (ΔT) was varied between ?8 and +8°C, and h was determined by linear regression analysis as the slope of ΔT vs. heat flux. Mean ΔT was determined for surface temperatures between 36 and 38°C, as similar mean skin surface temperatures have been found in volunteers. The covered area was estimated to be 0.35 m². Results: Total heat flow from the blanket to the manikin was different for surface temperatures between 36 and 38°C. At a surface temperature of 36°C the heat flows were higher (4–26.6 W) than at surface temperatures of 38°C (2.6–18.1 W). The highest total heat flow was delivered by the WarmTouch? system with the CareDrape? upper body blanket (18.1–26.6 W). The lowest total heat flow was delivered by the Warm‐Gard^® system with the single use upper body blanket (2.6–4 W). The heat exchange coefficient varied between 15.1 and 36.2 W m^?2 °C^?1, and mean ΔT varied between 0.5 and 3.3°C. Conclusion: We found total heat flows of 2.6–26.6 W by forced‐air warming systems with upper body blankets. However, the changes in heat balance by forced‐air warming systems with upper body blankets are larger, as these systems are not only transferring heat to the body but are also reducing heat losses from the covered area to zero. Converting heat losses of approximately 37.8 W to heat gain, results in a 40.4–64.4 W change in heat balance. The differences between the systems result from different heat exchange coefficients and different mean temperature gradients. However, the combination of a high heat exchange coefficient with a high mean temperature gradient is rare. This fact offers some possibility to improve these systems.     

The prehospital management of hypothermia — An up-to-date overview

BackgroundAccidental hypothermia concerns a body core temperature of less than 35 °C without a primary defect in the thermoregulatory system. It is a serious threat to prehospital patients and especially injured patients, since it can induce a vicious cycle of the synergistic effects of hypothermia, acidosis and coagulopathy; referred to as the trauma triad of death. To prevent or manage deterioration of a cold patient, treatment of hypothermia should ideally begin prehospital. Little effort has been made to integrate existent literature about prehospital temperature management. The aim of this study is to provide an up-to-date systematic overview of the currently available treatment modalities and their effectiveness for prehospital hypothermia management.Data sourcesDatabases PubMed, EMbase and MEDLINE were searched using the terms: “hypothermia”, “accidental hypothermia”, “Emergency Medical Services” and “prehospital”. Articles with publications dates up to October 2017 were included and selected by the authors based on relevance.ResultsThe literature search produced 903 articles, out of which 51 focused on passive insulation and/or active heating. The most effective insulation systems combined insulation with a vapor barrier. Active external rewarming interventions include chemical, electrical and charcoal-burning heat packs; chemical or electrical heated blankets; and forced air warming. Mildly hypothermic patients, with significant endogenous heat production from shivering, will likely be able to rewarm themselves with only insulation and a vapor barrier, although active warming will still provide comfort and an energy-saving benefit. For colder, non-shivering patients, the addition of active warming is indicated as a non-shivering patient will not rewarm spontaneously. All intravenous fluids must be reliably warmed before infusion.ConclusionAlthough it is now accepted that prehospital warming is safe and advantageous, especially for a non-shivering hypothermic patient, this review reveals that no insulation/heating combinations stand significantly above all the others. However, modern designs of hypothermia wraps have shown promise and battery-powered inline fluid warmers are practical devices to warm intravenous fluids prior to infusion. Future research in this field is necessary to assess the effectiveness expressed in patient outcomes.     

Randomized Prospective Comparison of Forced Air Warming Using Hospital Blankets versus Commercial Blankets in Surgical Patients

Background: The purpose of this study was to evaluate the efficacy of an experimental approach to forced air warming using hospital blankets or a Bair Hugger warming unit (Augustine Medical Inc., Eden Prairie, MN) to create a tent of warm air.

Methods: Adult patients undergoing major surgery were studied. Patients were randomized to receive forced air warming using either a commercial Bair Hugger blanket (control group, n = 44; set point, 43[degrees]C) or standard hospital blankets (experimental group, n = 39; set point, 38[degrees]C). Distal esophageal temperatures were monitored. Patients were contacted the following day regarding any problems with the assigned warming technique.

Results: Surface area covered was 36 +/- 12% (mean +/- SD) in the experimental group and 40 +/- 10% in the control group. Final temperatures at the end of surgery were similar between groups: experimental, 36.2 +/- 0.6[degrees]C; control, 36.4 +/- 0.7[degrees]C. A similar number of patients had esophageal temperature less than 36[degrees]C at the end of surgery in both groups (experimental, 12 of 39 [31%]; control, 12 of 44 [27%]). The majority of patients were satisfied with their anesthetic and warming technique: experimental, 38 of 39 patients; control, 44 of 44 patients. There were no thermal injuries.     

Usefulness of monitoring forehead deep-tissue temperature as an index of core temperature in adult patients undergoing laparotomies under general anesthesia--investigation in operating rooms with air-movement control system using vertical flow

BACKGROUND: Acute changes in air temperature in the vicinity of the patents' forehead may impair clinical usefulness of the forehead deep-tissue thermometry. We thus investigated usefulness of monitoring the forehead deep-tissue temperature as an index of core temperature in 12 adult patients undergoing laparotomies in operating rooms with air-movement control system using vertical flow. METHODS: Nasopharyngeal, forehead deep-tissue, palm deep-tissue, and fingertip skin-surface temperatures were recorded during surgery every 5 minutes in operating rooms where room temperature was thermostatically controlled at approximately 25 degrees C. The patients were not actively warmed with forced-air warmers, but covered with cotton blankets where possible. The deep-tissue and fingertip skin-surface temperatures were compared with the nasopharyngeal temperature using regression and Bland and Altman's analyses. RESULTS: The four temperatures continued decreasing during surgery, and the nasopharyngeal temperature decreased to below 36 degrees C 2 hours after induction of anesthesia. Only the forehead deep-tissue temperature satisfactorily correlated with the nasopharyngeal temperature (r = 0.76, n = 300, P < 0.0001). The difference between nasopharyngeal and forehead temperatures was +0.26 degree C, and its standard deviation was 0.34 degree C. CONCLUSIONS: The forehead deep-tissue temperature has sufficient accuracy and precision for clinical use in operating rooms with air-movement control system using vertical flow. However, the core temperature appears to be slightly underestimated with the forehead deep-tissue thermometry.     

A "SINGLE" VENTILATOR HOSE

A logical approach to the design of ventilator hoses indicatesthat because external power is producing flow, the inspiratorylimb can be made of narrower bore than the expiratory limb.A double-lumen concentric hose has been designed, the characteristicsof which are compared with the standard ventilator tubing underthe type of conditions encountered when ventilating intubatedpatients. The new tube is light and inexpensive.     

Major full thickness skin burn injuries in premature neonate twins

Burns in neonates have been reported following the use of pulse oximeters, various electrodes, chemical disinfecting agents and phototherapy blankets. Burn injuries in premature neonates are very rare and there have been no reports on major full skin thickness injuries. This case reports on preterm neonate male twins delivered at a Community Hospital. After the delivery they were placed on water warmers for 15-20 min and then transported into incubators. Burn injuries were noticed 1h after the delivery. Infant One, weight 1500 g, had an injury of 20% TBSA on his dorsum, waist and buttocks. The other infant, weight 1835 g, had an injury of 14% TBSA on the same areas. The infants were transported to the University Hospital. At the seventh day after the injury they recovered from respiratory distress and surgical procedures started. The eschar was excised deep to fascia and wounds were grafted with 0.1mm thickness skin grafts harvested from the thigh and cut into islets. Autografts were protected by overlay with fresh allograft harvested from the twins' father. Surgery procedures were performed in two steps, each second day, not exceeding 10% of total body area during excision. Donor sites healed at the eighth day after the surgery. Burn wounds healed gradually by way of spontaneous replacement of allograft and wound closure by spontaneous epithelization from the autograft islets. Eighteen days after the surgery all the grafted wounds were found epithelized. We conclude that in premature neonates relatively low temperatures may cause deep burn injuries. We recommend the delivery of preterm childbirths at well equipped facilities with staff qualified in nursing of premature neonates.     

Filters in anaesthesia and intensive care

The use of various types of filters in anaesthesia and intensive care seems ubiquitous, yet authentication of the practice is scarce and controversies abound. This review examines evidence for the practice of using filters with blood and blood product transfusion (standard blood filter, microfilter, leucocyte depletion filter), infusion of fluids, breathing systems, epidural catheters, and at less common sites such as with Entonox inhalation in non-intubated patients, forced air convection warmers, and air-conditioning systems. For most filters, the literature failed to support routine usage, despite this seemingly being popular and innocuous. The controversies, as well as guidelines if available, for each type of filter, are discussed. The review aims to rationalize the place of various filters in the anaesthesia and intensive care environment.     

Compressed-air power tools in orthopaedic surgery: exhaust air is a potential source of contamination

OBJECTIVES: To determine if the exhaust from surgical compressed-air power tools contains bacteria and if the exhaust leads to contamination of sterile surfaces. DESIGN: Bacteriologic study of orthopaedic power tools. SETTING: Level I trauma center operative theater. PATIENTS/PARTICIPANTS: None. INTERVENTION: Part I. Exhaust from two sterile compact air drills was sampled directly at the exhaust port. Part II. Exhaust from the drills was directed at sterile agar plates from varying distances. The agar plates represented sterile surfaces within the operative field. Part III. Control cultures. A battery-powered drill was operated over open agar plates in similar fashion as the compressed-air drills. Agar plates left open in the operative theater served as controls to rule out atmospheric contamination. Random cultures were taken from agar plates, gloves, drills, and hoses. MAIN OUTCOME MEASUREMENT: Incidence of positive cultures. RESULTS: In Part I, all filters from both compressed-air drill exhausts were culture negative ( = 0.008). In Part II, the incidence of positive cultures for air drills number one and number two was 73% and 82%, respectively. The most commonly encountered organisms were, coagulase-negative Staphylococcus, and Micrococcus species. All control cultures from agar plates, battery-powered drill, gloves, and hoses were negative ( < 0.01). CONCLUSIONS: Exhaust from compressed-air power tools in orthopaedic surgery may contribute to the dissemination of bacteria onto the surgical field. We do not recommend the use of compressed-air power tools that do not have a contained exhaust.     

大鼠原位肝移植胆道外引流模型的改进

目的 对原有大鼠原位肝移植胆道外引流模型进行改进,建立一个稳定、可靠的大鼠原位肝移植胆道外引流模型,为动态检测移植术后胆汁中各项指标提供可能.方法 根据Kamada和王振杰报道的术式加以多项技术改进建立大鼠原位肝移植胆道外引流模型,胆总管内置硬膜外导管外接合适口径的软管,高位空肠造瘘并置入软管,两软管引至右侧腹壁皮下对口相接.结果 共施行大鼠原位肝移植98次,24h动物存活率达94.1%,1周动物存活为88.2%.结论 此方法简便易行,成功率高,并发症少且可大大提高术后生存率和生存时间,是一种长期、动态收集胆汁的理想模型.     

Effect of forced-air heaters on perfusion and temperature distribution during and after open-heart surgery

Objectives: After cardiopulmonary bypass, patients often show redistribution hypothermia, also called afterdrop. Forced-air blankets help to reduce afterdrop. This study explores the effect of forced-air blankets on temperature distribution and peripheral perfusion. The blood perfusion data is used to explain the observed temperature effects and the reduction of the afterdrop. Methods: Fifteen patients were enrolled in a randomised study. In the test group (n = 8), forced-air warmers were used. In the control group (n = 7), only passive insulation was used. Core and skin temperatures and thigh temperatures at 0, 8, 18 and 38 mm depth were measured. Laser Doppler flowmetry (LDF) was used to record skin perfusion from the big toe. Blood flow through the femoral artery was determined with ultrasound. Results: Afterdrop in the test group was smaller than in the control group (1.2 ± 0.2 °C vs 1.8 ± 0.7 °C: P = 0.04) whilst no significant difference in mean tissue thigh temperature was found between the groups. Local skin temperature was 2.5–3.0 °C higher when using forced-air heaters. However, skin perfusion was unaffected. Ultrasound measurements revealed that leg blood flow during the first hours after surgery was reduced to 70% of pre- and peri-operative values. Conclusions: Forced-air blankets reduce afterdrop. However, they do not lead to clinical relevant changes in deep thigh temperature. LDF measurements show that forced-air heating does not improve toe perfusion. The extra heat especially favours core temperature. This is underlined by the decrease in postoperative leg blood flow, suggesting that the majority of the warmed blood leaving the heart flows to core organs and not to the periphery.     

Perforated or gangrenous appendicitis treated with aminoglycosides. How do bacterial cultures influence management?

To study the influence of bacterial culture data on the clinical management of gangrenous or perforated appendicitis, we reviewed records of 104 patients who had been treated empirically with aminoglycoside antibiotics. Culture results appeared to influence antibiotic therapy in only 7 patients (7%). The routine cultures obtained at appendectomy affected therapy in only 2 patients. Discriminant analysis identified postoperative infectious complications and related factors as the principal determinants of culture utility. We conclude that, in patients with perforated appendicitis treated empirically with aminoglycoside combination regimens, culture results were seldom used for clinical management except in instances of postoperative infectious complication. Routine cultures and Gram's stains of perforated appendicitis, however, should still be obtained (1) to allow epidemiologic tracking in the hospital; (2) to identify organisms that are recovered infrequently but may cause serious disease (eg, Clostridium); and (3) because newer antibiotics are replacing aminoglycosides in the treatment of perforated appendicitis.     

Warming of patients during Caesarean section: a telephone survey*

We contacted the duty obstetric anaesthetist in 219 of the 220 consultant‐led maternity units in the UK (99.5%) and asked about departmental and individual practice regarding temperature management during Caesarean section. Warming during elective Caesarean section was routine in 35 units (16%). Intravenous fluid warmers were available in 213 units (97%), forced air warmers were available in 211 (96%) and warming mattresses were available in 42 (19%). Only 18 (8%) departments had specific guidelines for temperature management during Caesarean section. Personal intra‐operative practice was variable, although all of those contacted would initiate some form of active temperature management after a mean (SD) volume of blood loss of 1282 (404) ml, length of surgery of 78 (24) min, or core body temperature (if measured) of median (IQR [range]), 36 (35.5–36 [34–37.2]) °C.     

Full body forced air warming: commercial blanket vs air delivery beneath bed sheets

Purpose

Single-use commercial forced air warming blankets serve only to distribute heated air from a blower. Standard bed sheets may be equally effective in delivering hot air within a lower body field and at lower cost.

Methods

Heated forced air at 38° and 43° was delivered within a simulated full-body field beneath standard hospital bed sheets or via a BAIR Model 315 commercial blanket. The air temperatures maintained within, as well as the caloric uptake of standard bodies containing 1000 ml water, were studied under standard simulated operating room conditions. Thermal input was provided by one Bair Hugger Model 500 Warming Unit and hospital acquisition cost for materials were calculated.

Results

Air temperatures measured within the full body field at the three test sites were as great or greater using bed sheets (33.4–35.8°) as with the commercial blanket (31.1–33.9°), in spite of the 5° cooler outlet temperature air settings @ 38° vs 43°, respectively (P = 0.003). Forced air delivered beneath bed sheets heated standardized thermal bodies twice as effectively as commercial blankets using identically warmed (38°) forced air and heated as well as, or better, at the 38° setting than did the commercial blanket at the 43° setting. Calculated acquisition costs for sheets vs commercial blankets were $0.76 vs $18.00 US, respectively.

Conclusion

The simplicity, efficacy and economy of containing 38° warm air beneath bed-sheets offer several advantages over commercial blankets and warrant further study.