Predicting the possibility of decompression sickness, or bends, in manned orbital flights

Predicting possible decompression, or bends, in manned orbital flight

A review of the influence of physical condition parameters on a typical aerospace stress effect: Decompression sickness

The study examines data on episodes of decompression sickness, particularly from recent Navy work in which the event occurred under multiple stress conditions, to determine the extent to which decompression sickness might be predicted on the basis of personal characteristics such as age, weight, and physical condition. Such information should ultimately be useful for establishing medical selection criteria to screen individuals prior to participation inactivities involving extensive changes in ambient pressure, including those encountered in space operations. The main conclusions were as follows. There is a definite and positive relationship between increasing age and weight and the likelihood of decompression sickness. However, for predictive purposes, the relationship is low. To reduce the risk of bends, particularly for older individuals, strenuous exercise should be avoided immediately after ambient pressure changes. Temperatures should be kept at the low end of the comfort zone. For space activities, pressure changes of over 6-7 psi should be avoided. Prospective participants in future missions such as the Space Shuttle should not be excluded on the basis of age, certainly to age 60, if their general condition is reasonably good and they are not grossly obese. (Modified author abstract

Cardiac arrest in a child during a combined general epidural anesthesia procedure

An increased risk of perioperative cardiac arrest in children, in comparison to adults, has been recognized. A number of factors associated with perioperative cardiac arrest have been identified, including young age, comorbidities, and emergency surgery. Since anesthesia-related cardiac arrest is uncommon, a multi-related database is required to understand the mechanisms of cardiac arrest and to develop preventive strategies. Most cardiac arrests occur during induction (37%) or maintenance (45%) of anesthesia, usually following one or more of the following antecedent events, i.e., bradycardia (54%), hypotension (49%), abnormality of oxygen saturation as measured by pulse oximetry (48%), inability to measure blood pressure (25%), abnormality of endtidal CO2 (21%), cyanosis (21%), or arrhythmia (18%). In 11% of cases, cardiac arrest occurred without recognized warning.1 There are only few reports in the literature, and in Kariadi Hospital, none has ever been reported. The aim of this report is to identify and discuss possible causes of cardiac arrest and to anticipate its complications

Feasibility of upright patient positioning and intubation success rates at two academic emergency departments

Objectives Endotracheal intubation is most commonly taught and performed in the supine position. Recent literature suggests that elevating the patient's head to a more upright position may decrease peri-intubation complications. However, there is little data on the feasibility of upright intubation in the emergency department. The goal of this study was to measure the success rate of emergency medicine residents performing intubation in supine and non-supine, including upright positions. Methods This was a prospective observational study. Residents performing intubation recorded the angle of the head of the bed. The number of attempts required for successful intubation was recorded by faculty and espiratory therapists. The primary outcome of first past success was calculated with respect to three groups: 0–10° (supine), 11–44° (inclined), and ≥ 45° (upright); first past success was also analyzed in 5 degree angle increments. Results A total of 231 intubations performed by 58 residents were analyzed. First pass success was 65.8% for the supine group, 77.9% for the inclined group, and 85.6% for the upright group (p = 0.024). For every 5 degree increase in angle, there was increased likelihood of first pass success (AOR = 1.11; 95% CI = 1.01–1.22, p = 0.043). Conclusions In our study emergency medicine residents had a high rate of success intubating in the upright position. While this does not demonstrate causation, it correlates with recent literature challenging the traditional supine approach to intubation and indicates that further investigation into optimal positioning during emergency department intubations is warranted

The speed of decreasing of arterial oxygen saturation following induction of anesthesia, using 3 methods of pre-oxygenation techniques

Background and aim: Determination of preoxygenation before anesthesia is an important factor in prevention of hypoxia and its complications. Regarding the height of Shahrekord from the sea surface (2061 m) and low level of oxygen pressure in this area (600 mg), this study was aimed to determine the onset of desaturation of oxygen following, using of three pre-oxygenation methods in apnostic adult healthy patients. Methods: In this clinical single blind study, sixty-six healthy, non-smoker adults undergoing elective surgery were randomly divided into three groups. Following the record of systolic and diastolic blood pressure and heart pulse from the patients, group one were not pre-oxygenated, groups two and three were pre-oxygenated with 50% oxygen and nitrous oxide and 100% oxygen, respectively for three minutes. After induction of the same anesthesia in the 3 groups, the patients were kept in apnostic until their saturated pressure O2 (SpO2) decreased to 91%. Subsequently, their systolic and diastolic blood pressure and heart pulse required to achieve SpO2 of 91% were measured. The data were analyzed using Chi-square and ANOVA tests. Results: Mean age of the patients was 30.5±14.1 in whom 58% of them were male. All of the three groups were sex and age matched (p>0.05). The delay time to achieve SpO2 in group one, group two and group three were 44±16, 114.3±36.8 and 241.6±84, respectively (p<0.001). In all of the 3 groups, the increasing of heart pulse after the intervention was significantly different compared to before that (p<0.001). However, the difference was not significant between the groups. Conclusion: Pre-oxygenation of the patients for 3 min. before induction of anesthesia with normal breathing and with 100% oxygen would significantly increase the time required for oxygen saturation of the patients to 91%

A comparative study of different induction techniques (Propofol-Placebo, Propofol-Ephedrine and Propofol- Placebo-Crystalloid) on intubating conditions after rocuronium administration

This was a prospective randomized double blind controlled study to compare intubating conditions at 60 seconds with rocuronium 0.6 mg/kg by using three different induction techniques: propofol-placebo (PP), propofol-ephedrine (PE) and propofol-placebocrystalloid (PC). Ninety patients were included and randomly allocated to receive one of the three combinations. The patients were induced using fentanyl 2 μg/kg, followed by propofol 2.5 mg/kg with normal saline as placebo (Group PP and Group PC) or ephedrine 70 μg/kg (Group PE) given over 30 seconds. Subsequently, rocuronium 0.6 mg/kg was given over five seconds and endotracheal intubations were performed 60 seconds later. Intubating conditions were clinically acceptable in all patients except in four patients in PP group, who had poor intubating conditions. The proportion of excellent intubating conditions was significantly highest in Group PE (94%) followed by Group PC (81%) and lowest in Group PP (50%). In conclusion, induction with propofol-ephedrine and propofol-placebo-crystalloid combinations provided significantly better intubating conditions than propofol alone, when rocuronium 0.6 mg/kg was used for intubation at 60 second

The effects of different rates of ascent on the incidence of altitude decompression sickness

The effect of different rates of ascent on the incidence of altitude decompression sickness (DCS) was analyzed by a retrospective study on 14,123 man-flights involving direct ascent up to 38,000 ft altitude. The data were classified on the basis of altitude attained, denitrogenation at ground level, duration of stay at altitude, rest or exercise while at altitude, frequency of exercise at altitude, and ascent rates. This database was further divided on the basis of ascent rates into different groups from 1000 ft/min up to 53,000 ft/min. The database was analyzed using multiple correlation and regression methods, and the results of the analysis reveal that ascent rates influence the incidence of DCS in combination with the various factors mentioned above. Rate of ascent was not a significant predictor of DCS and showed a low, but significant multiple correlation (R=0.31) with the above factors. Further, the effects of rates below 2500 ft/min are significantly different from that of rates above 2500 ft/min on the incidence of symptoms (P=0.03) and forced descent (P=0.01). At rates above 2500 ft/min and up to 53,000 ft/min, the effects of ascent rates are not significantly different (P greater than 0.05) in the population examined while the effects of rates below 2500 ft/min are not clear

Anaesthetic breathing circuit obstruction due to blockage of tracheal tube connector by a foreign body - two cases

Publisher's copy made available with the permission of the publisher© 1999 Australian Society of AnaesthetistsTwo cases are presented which illustrate the disastrous consequences possible when an anaesthetic breathing circuit is obstructed by a foreign body. Despite reports of previous similar cases, work practices and equipment manufacture or design continue to allow for such events to occur. The importance of both pre-anaesthetic testing of the entire circuit including attachments such as the tracheal tube connector and filters, and the removal of these parts should obstruction occur, is emphasised. Use of “clear” transparent breathing circuit components and opaque or brightly coloured packaging and caps which could potentially cause obstruction should decrease the incidence and facilitate the diagnosis of this problem.M.J. Foreman, D. G. Moye

Sudden death after open gastric bypass surgery

Purpose: Gastric bypass surgery has become a relatively low-risk bariatric surgical intervention in a high-risk patient population (Nguyen et al., Arch Surg, 141:445-449, 2006; Buchwald et al. JAMA, 13:1724-1737, 2004). Surgical interventions in patients suffering from morbid obesity are typically associated with excess morbidity (Parikh et al., Am Surg, 73:959-962, 2007). Though overall mortality after bariatric surgery is <1% is low (Mason et al., Obes Surg, 17:9-14, 2007), some surgical complications such as anastomotic leaks, staple line disruption and bowel obstruction may still impact on postoperative outcome (Parikh et al., Am Surg, 73:959-962, 2007; Mason et al., Obes Surg, 17:9-14, 2007). Early symptoms are often missed, as clinical presentation may be discreet, inexistent or falsely attributed to obesity. Methods: This case report refers to a patient in whom discomfort and agitation associated with a rise in temperature heralded a fulminant septic shock syndrome precipitating his death. Literature on early complications and management after gastric bypass is reviewed. Conclusion: A high level of suspicion should be present in the case of an unexpected postoperative deterioration of the patient's general condition. Time to treat may be very short (Mason et al., Obes Surg, 17:9-14, 2007). Computed tomography is mandatory to rule out pulmonary embolism and bypass obstructio