Performance of the 1 mg dexamethasone suppression test in patients with severe obesity

OBJECTIVE

To analyze the performance of the 1 mg dexamethasone suppression test (DST) in patients with obesity. Special attention was paid to the influence of interfering medication on DST.

METHODS

In this prospective cohort study (Mannheim Obesity Study), patients with obesity were evaluated before bariatric surgery. For evaluation of hypercortisolism, a 1 mg dexamethasone-suppression test (DST) in all subjects was performed. Medication was assessed for possible interference.

RESULTS

Two hundred seventy-eight patients with a mean age of 42.3 years (68.8% women) and a mean BMI of 47.9 ± 8.4 kg/m(2) were screened. Insufficient suppression of cortisol after DST was found in 24 patients (8.6%). In two patients hypercortisolism was confirmed. The specificity for DST was calculated at 92.0%. Only CYP3A4 inducers (n = 22, 7.9%) and estrogen therapy (n = 17, 6.1%) were significantly associated with falsely elevated cortisol after DST. Regression analysis excluded any interrelation between DST and anthropometry.

CONCLUSIONS

Low prevalence of hypercortisolism (0.7 or <1.8%) was found. Specificity of DST in this cohort typically screened for hypercortisolism was 92.0% (≤ 50 nmol/L). DST should be avoided in patients taking CYP3A4 inducers or estrogen therapy, due to their significant interaction. In summary, the 1 mg DST is an adequate test for screening for hypercortisolism even in patients with extreme obesity.

[Injuries caused by pressure differences while diving]

Barotraumas are caused by pressure differences. As described by Boyle's Law, barotraumas develop during the descent phase of diving (and much more rarely during the ascent). The most frequently affected are the ears and paranasal sinuses, in addition to the facial skin and eyes. The most important preventive measure is performing pressure compensation in the affected body cavities. Barotrauma is treated symptomatically.

[Medical aspects of diving in the tropics]

Scuba diving vacations in tropical surroundings belong to the repertoire of most divers. In addition to carefully making travel plans and taking care of the necessary vaccinations and appropriate malaria prophylaxis, the following points also must be observed. The flight itself affects diving safety. In particular, a too short time interval between diving and the return flight can lead to decompression problems. Because most of the diving areas are reached by ship, many divers need a prophylaxis against motion sickness. Moreover, external otitis occurs more frequently while diving in the tropics. Finally, there is potential danger from the sea inhabitants, primarily from scorpion fishes, Portuguese Man-of-Wars, box jellyfishes as well as cone snails.

[Problems in the deep: the isopression phase]

Fundamentally, accident mechanisms during the isopression phase of diving are primarily dependent upon the partial pressures of the respiratory gases. An increased nitrogen partial pressure leads to compressed-air intoxication; an increased oxygen partial pressure while diving with oxygen-enriched gas mixtures can trigger an oxygen-induced convulsion. Elevated pCO2 can be provoked by inadequate breathing and/or physical exertion at greater diving depths. Through an adjusted diving behavior and observation of the limits, these problems could be easily avoided.

[Decompression injuries]

A decompression accident occurs during uncontrolled dive ascent with diving equipment. Through the rapid decrease in the surrounding pressure, gas bubbles form in the blood and tissues. Depending upon the mechanism of onset, the decompression illness (DCI) is classified as decompression sickness (DCS) or arterial gas embolism (AGE). The therapy consists of administering, as quickly as possible, 100% oxygen as well as a volume substitution. The treatment is continued in a recompression chamber.

[Diving fitness for scuba divers--what the primary care physician should know]

The diving fitness medical examination serves to show and reveal medical conditions that are a contraindication for diving or to evaluate the risk of preexisting conditions. For this reason, it should never have the character of a certification given as a matter of courtesy. Fitness to dive is given if the candidate is healthy and when there are no pathological findings. Even with deviations from the norm, diving is still possible, but with restrictions. Important organ systems for the diving fitness examination are the cardiovascular system, the respiratory organs and the ears. In addition, adequate eyesight is important. The German Society of Diving and Hyperbaric Medicine (GTOUM) has drawn up recommendations on the examination of scuba divers to assist the physician (www.gtuem.org).

[Before going on a diving holiday--consider this]

A prerequisite for all those who go in for the sport of scuba diving is mental and physical fitness. This must be checked within the framework of an examination for diving fitness before first taking up the sport, and should be rechecked every one to three years. For fitness for diving, not only lung function, ECG and tubal function need to be normal--the psychological profile of the holiday maker also plays an important role under water. For he or she must be able rapidly and reliably to recognize a dangerous situation and to react to it appropriately. Thorough training and the compliance with the rules of diving offer protection from many of the risks of this underwater sport--for example, problems with the ears or sinuses can be avoided. The most common cause of fatal diving accidents is a barotrauma of the lung with rupture of the alveoli on ascending.

[Axillary blockade of the brachial plexus. A prospective evaluation of 1133 cases of plexus catheter anesthesia]

The results of 1133 axillary catheter brachial blocks are reported. Effectiveness and side-effects were monitored in a prospective manner over a period of 1 year.

METHOD

The puncture was performed with an 18-gauge plastic cannula fitted with a solid steel stylet. The stylet has a 45 degrees, short bevel with rounded edges. When puncturing the axillary neurovascular sheath, no attempt was made to elicit paresthesias with the needle. A distinct "click" and very easy advancement of the plastic cannula were signs of being well inside the neurovascular sheath. To confirm the correct positioning, 0.5-3 ml refrigerated saline solution were injected. If no paresthesias could be produced, a new puncture was performed using a nerve stimulator. The plastic cannula was fixed to the skin. For long-lasting operations or if postoperative analgesia or sympatholysis was required, a more flexible catheter was introduced through the plastic cannula. As an initial dose 40 ml 1% mepivacaine was injected via the cannula. If there was an insufficient block after 20 min, another 20 ml 1% mepivacaine was given. For long-lasting operations, 40 ml 1% mepivacaine was injected every 2 h.

RESULTS

Surgery was completed in 72% of patients; 24% required some form of supplementation including 17.2% of patients who received a "top-up" after 20 min (Table 1). In 3.8% of cases the technique was considered to be a complete failure, meaning that patients needed some type of general anesthesia including the use of i.v. ketamine.(ABSTRACT TRUNCATED AT 250 WORDS)