Pressure-dependent changes in haematocrit and plasma volume during anaesthesia, a randomised clinical trial.

BACKGROUND: Induction of general anaesthesia has been shown to cause haemodilution and an increase in plasma volume. The aim of this study was to evaluate whether prevention of hypotension during anaesthesia induction could avoid haemodilution. METHODS: Twenty-four cardiac surgery patients, 66 ± 10 years, were randomised to receive either norepinephrine in a dose needed to maintain mean arterial blood pressure (MAP) at pre-anaesthesia levels after induction or to a control group that received vasopressor if MAP decreased below 60 mmHg. No fluids were infused. Changes in plasma volume were calculated with standard formula: 100 × (Hct(pre)/Hct(post) - 1)/(1 - Hct(pre)). Arterial blood gas was analysed every 10 minutes and non-invasive continuous haemoglobin (SpHb) was continuously measured. RESULTS: Pre-anaesthesia MAP was 98 ± 7 mmHg. Ten minutes after anaesthesia induction, the haematocrit decreased by 5.0 ± 2.5% in the control group compared with 1.2 ± 1.4% in the intervention group, which corresponds to increases in plasma volume by 310 ml and 85 ml respectively. MAP decreased to 69 ± 15 mmHg compared to 92 ± 10 mmHg in the intervention group. The difference maintained throughout the 70 min intervention period. The change in haemoglobin level measured by blood gas analysis could not be detected by SpHb measurement. The mean bias between the SpHb and blood gas haemoglobin was 15 g/l. CONCLUSION: During anaesthesia induction, haematocrit decreases and plasma volume increases early and parallel to a decrease in blood pressure. This autotransfusion is blunted when blood pressure is maintained at pre-induction levels with norepinephrine.

[Diagnostics and treatment decisions in acute compartment syndrome. Results of a survey in German hospitals]. / Diagnostik und Therapieentscheidung beim akuten Kompartmentsyndrom. Ergebnisse einer Umfrage in deutschen Kliniken.

BACKGROUND AND OBJECTIVES: The presented survey was intended to evaluate whether a standardization of diagnostics and therapy for acute compartment syndrome has been achieved. MATERIALS AND METHODS: University hospitals, academic teaching hospitals, and county hospitals in Germany were included. RESULTS: A total of 38% (n=120) of all contacted hospitals participated in this study with questions mainly answered by consulting physicians (68%). In general the importance of the clinical examination was considered as being more important than other diagnostic measures. In cases where further diagnostics were necessary, the intramuscular pressure measurement was used most frequently. Of the participants 50% performed surgical fasciotomy based on the clinical examination in combination with the intramuscular pressure measurement; however, there were considerable differences between the participating hospitals with respect to the anatomical position of intramuscular measurements, the limiting value of the intramuscular pressure and the surgical technique for performing fasciotomy. CONCLUSION: According to the presented analysis the diagnosis and indications for surgical treatment in patients developing an acute compartment syndrome do not seem to be sufficiently clarified. The establishment of unified treatment guidelines could help to reduce the number of delayed diagnoses of compartment syndrome.

Cost analysis of surgically treated pressure sores stage III and IV.

Health-care costs associated with pressure sores are significant and their financial burden is likely to increase even further. The aim of this study was to analyse the direct medical costs of hospital care for surgical treatment of pressure sores stage III and IV. We performed a retrospective chart study of patients who were surgically treated for stage III and IV pressure sores between 2007 and 2010. Volumes of health-care use were obtained for all patients and direct medical costs were subsequently calculated. In addition, we evaluated the effect of location and number of pressure sores on total costs. A total of 52 cases were identified. Average direct medical costs in hospital were €20,957 for the surgical treatment of pressure sores stage III or IV; average direct medical costs for patients with one pressure sore on an extremity (group 1, n = 5) were €30,286, €10,113 for patients with one pressure sore on the trunk (group 2, n = 32) and €40,882 for patients with multiple pressure sores (group 3, n = 15). The additional costs for patients in group 1 and group 3 compared to group 2 were primarily due to longer hospitalisation. The average direct medical costs for surgical treatment of pressure sores stage III and IV were high. Large differences in costs were related to the location and number of pressure sores. Insight into the distribution of these costs allows identification of high-risk patients and enables the development of specific cost-reducing measures.

Medium-term cost analysis of breast reconstructions in a single Dutch centre: a comparison of implants, implants preceded by tissue expansion, LD transpositions and DIEP flaps.

BACKGROUND: Free flap breast reconstruction (BR) is generally believed to be more expensive than implant BR, but costs were previously shown to level out over time due to complications and re-operations. The aim of this study was to assess the economic implications of four BR techniques: silicone prosthesis (SP), implant preceded by tissue expansion (TE/SP), latissimus dorsi transposition with or without implant (LD ± SP) and deep inferior epigastric perforator (DIEP) flap. METHODS: A prospective historic cohort study was performed to evaluate intramural medical costs in 427 patients, who had undergone BR between 2002 and 2009. Short- and medium-term complications were incorporated. In addition, 58 patients, who had recently undergone BR, participated in a questionnaire study to prospectively evaluate extramural medical and non-medical costs. Estimates of mean short- and medium-term costs are presented per patient. RESULTS: Intramural medical costs for BR and short-term complications for unilateral DIEP flaps (€ 12,848) and TE/SP reconstructions (€ 12,400) were significantly higher than those for LD ± SP reconstructions (€ 5804), which, in turn, were more expensive than SP reconstructions (€ 4731). In bilateral cases, costs of TE/SP (€ 12,723) and LD ± SP (€ 10,760) reconstructions were comparable, while DIEP flaps (€ 15,747) were significantly more expensive and SP reconstructions were significantly cheaper (€ 6784). Overall, the medium-term costs for complications and additional operations were not significantly different (€ 3017-€ 4503). Extramural medical costs and non-medical costs were approximately € 9300 per stage, regardless of technique. CONCLUSIONS: Differences in short-term costs between techniques did not level out during follow-up and SP reconstructions remained least expensive. Single-stage SP reconstructions, however, are not suitable for all patients due to high complication rates. Definite implant placement is therefore increasingly preceded by tissue expansion at more comparable costs to autologous BR. Incorporation of non-medical costs into the cost analysis would render two-stage procedures more costly than autologous BR. To achieve the optimal result, careful patient selection is critical. Only in select cases where two options are equally applicable, cost comparison becomes a valid argument for treatment selection.

The pleasing end result after DIEP flap breast reconstruction: a review of additional operations.

BACKGROUND: Breast reconstruction with deep inferior epigastric perforator (DIEP) flaps is typically a three-stage procedure, but additional operations may be required to deal with complications or to improve the aesthetic result. The purpose of this study was to evaluate the total number of operations needed after DIEP flap breast reconstruction to achieve a satisfactory end result for the patient. PATIENTS AND METHODS: From December 2002 to October 2006, 99 DIEP flap breast reconstructions obtained an end result in 72 patients. Data were collected in a structured database. Additional operations and complications were evaluated for the entire group. A study-specific questionnaire was used to evaluate patient satisfaction. RESULTS: The mean number of additional operations was 1.4 per patient. Patients with complications required more operations than patients without complications. Women who chose nipple reconstruction were younger than women who did not and were more likely to have had a primary or secondary than a tertiary reconstruction. The number of additional aesthetic operations was neither related to the occurrence of complications during the initial reconstruction, nor to patient satisfaction. Overall, patients were very satisfied with the end result. CONCLUSIONS: Completion of DIEP flap breast reconstruction involved the initial reconstruction and an average of 1.4 additional operations. Patients were generally very satisfied with the end result.

Optical-level shifter and self-linearized optical modulator using a quantum-well self-electro-optic effect device.

We demonstrate an optical-level shifter and a modulator whose transmission varies linearly with drive current, both based on a new, negative-feedback mode of operation of the recently discovered quantum-well self-electro-optic effect device. The system is compatible with both laser diodes and low-power semiconductor electronics and is applicable in both analog and digital optical processing. An extension of the system gives inverted, linear modulation of a coherent beam by an incoherent light source.

Optically pumped ultrashort cavity In(1-x) Ga(x) As(y) P(1-y) lasers: picosecond operation between 0.83 and 1.59 microm.

Ultrashort-cavity, thin-film lasers from In(1-x)Ga(x)As(y)P(1-y) of five different compositions, including InP and In(0.53)Ga(0.47)As, have been made to lase between 0.83 and 1.59 microm. The multitude of lasing wavelengths observed had line-to-line separations of less than 10 nm. The lasers were pumped with 1-psec pulses from a mode-locked dye laser. An output pulse of 6-psec duration was measured at a wavelength of 1.16 microm.