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Biomedical subjects

J Sear

Publications and source records attributed to J Sear.

12 recordsLinked to original sources

Perioperative fluid volume optimization following proximal femoral fracture.

BACKGROUND: Proximal Femoral Fracture (PFF) or 'hip fracture' is a frequent injury, and adverse outcomes are common. Many patients are elderly, with significant comorbidity. Several factors suggest the importance of developing appropriate techniques to optimize intravascular fluid volume. These may include protocols that enhance the efficacy of clinicians' assessments, invasive techniques such as oesophageal Doppler or central venous pressure monitoring, or advanced non-invasive techniques such as plethysmographic pulse volume determination. OBJECTIVES: To determine the optimal method of fluid volume optimization for adult patients undergoing surgical repair of hip fracture. Comparisons of fluid types (e.g. crystalloid vs. colloid) or of blood transfusion strategies or of other pharmacological interventions (e.g. inotropes) are not considered in this review. SEARCH STRATEGY: Randomized controlled trials (RCTs) since 1985 were identified by searching MEDLINE, EMBASE, the Cochrane Library, the Cochrane Anaesthesia Group's specialized Controlled Trials Register and bibliographies of retrieved articles. Relevant journals and conference proceedings were handsearched. SELECTION CRITERIA: RCTs comparing a fluid optimization intervention with normal practice (control) or with another fluid optimization intervention, in patients following PFF undergoing surgery of any type under anaesthesia of any type. DATA COLLECTION AND ANALYSIS: Searches and exclusion of clearly irrelevant articles were performed by one reviewer. Two reviewers examined independently the remaining studies, extracting study quality and results data. A wide range of short- and long-term outcome data was sought. Study quality was assessed using a ten-point instrument and studies were excluded if they did not meet the study criteria or if results were likely to be biased. Due to a lack of consistency in reporting, combination of data was not generally possible. MAIN RESULTS: Searches identified only four trials, of which two studies, randomizing a total of 130 patients, were of adequate quality and addressed the review question. Both studies were of invasive advanced haemodynamic monitoring during the intraoperative period only. One study randomized patients to 'normal care' or optimization using oesophageal Doppler; the second study randomized patients to 'normal care', oesophageal Doppler or central venous pressure monitoring. In each study, invasive monitoring led to a significant increase in volume of fluid infused and a reduction in length of hospital stay. The pooled Peto odds ratio for in-hospital fatality was 1.44 (95% confidence interval 0.45-4.62). Neither study followed patients beyond hospital discharge or assessed functional outcomes (for example return to previous accommodation). No serious complications were reported to be directly attributable to the monitoring interventions. There were no studies of protocol-guided fluid optimization or of advanced non-invasive techniques. REVIEWER'S CONCLUSIONS: Invasive methods of fluid optimization during surgery may shorten hospital stay, but their effects on other important, patient-centred, longer-term outcomes are uncertain. An adverse effect on fatality cannot be excluded. Other fluid optimization techniques have not been evaluated. The lack of randomized studies of adequate quality addressing this important question is disappointing given the high incidence and frequently adverse outcome of PFF. More research is needed.

Blood Volume↗

Echocardiographic evaluation of cardiac structure and function in elderly subjects with isolated systolic hypertension.

One hundred four participants in the Systolic Hypertension in the Elderly Program (SHEP) trial (mean age 71 +/- 6 years) were examined by Doppler echocardiography to gain information on the cardiac structural and functional alterations in isolated systolic hypertension. Participants had a systolic blood pressure greater than 160 mm Hg with diastolic blood pressure less than 90 mm Hg and were compared with 55 age-matched normotensive control subjects. Left ventricular mass index was significantly higher in the participants than in the normotensive subjects (103 +/- 28 versus 87 +/- 23 g/m2, p = 0.0014) and 26% of the participants met echocardiographic criteria for left ventricular hypertrophy compared with 10% of normotensive subjects. Left atrial index was also greater in participants than in normotensive subjects (2.26 +/- 0.32 versus 2.11 +/- 0.24 cm/m2, p = 0.005) and 51% of participants had left atrial enlargement. Doppler measures of diastolic filling were significantly different between the two groups, with peak atrial velocity higher (76 +/- 17 versus 69 +/- 17 cm/s, p = 0.02) and ratio of peak early to atrial velocity lower (0.76 +/- 0.23 versus 0.86 +/- 0.22, p = 0.0124) in participants. There was no correlation between left ventricular mass index and Doppler measures of diastolic function, but relative wall thickness correlated significantly with peak atrial velocity (r = 0.22, p = 0.016) and peak early to peak atrial velocity ratio (r = 0.24, p = 0.007). There was no difference in M-mode ejection phase indexes of systolic performance (shortening fraction and peak velocity of circumferential fiber shortening) between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

The uptake of bupivacaine in an in situ isolated perfused rabbit lung preparation.

A double indicator technique has been used in an in situ isolated perfused rabbit lung model to examine the first pass effect of the lung on systemic bupivacaine concentrations. Bupivacaine (0.5 mg/kg) was given in two consecutive boluses to six in situ isolated perfused New Zealand White rabbit lung preparations. The mean recovery (first bolus) of bupivacaine was 62.6% +/- 6.3 (S.E.M.), and 63.7% +/- 10.2 (second bolus), suggesting bupivacaine accumulation in the lung. The average mean transit time for bupivacaine was 280.5% +/- 24.1 and 264.8% +/- 36.7 longer than ICG (Indocyanine Green) following the first and second boluses respectively (P less than 0.01). There were no differences in the first pass effect of the lung between the first and second boluses of bupivacaine. The profiles of the bupivacaine concentrations suggest that uptake is followed by accumulation and later back diffusion. This has implications for conditions that decrease the uptake and therefore increase the risk of systemic toxicity.

Animals↗

Cefazolin and netilmicin serum levels during and after cardiac surgery with cardiopulmonary bypass.

The kinetics of cefazolin and netilmicin were studied in 10 patients undergoing elective cardiac surgery with hemodilution and cardiopulmonary bypass (CPB). During surgery, but before CPB, cefazolin, 25 mg/kg, and netilmicin, 2 mg/kg, were administered intravenously over 30 minutes. For the 48-hour period following CPB, cefazolin, 25 mg/kg, and netilmicin, 1 mg/kg, were administered intravenously every 8 hours. Initiation of CPB was accompanied by a 28% to 30% decrease in hematocrit and serum antibiotic levels. At the conclusion of surgery, cefazolin and netilmicin serum levels were 41 +/- 12 micrograms/L and 2.5 +/- 0.6 micrograms/mL (mean +/- SD), respectively. During the postoperative period, cefazolin levels were consistently greater than the minimum inhibitory concentration (MIC) for sensitive bacteria (4 micrograms/mL); average netilmicin levels were greater than MIC of sensitive bacteria (2 micrograms/mL) for 2 hours after antibiotic infusion. The netilmicin trough levels were 0.6 +/- 0.5 micrograms/mL. Pharmacokinetic parameters were determined using a model-independent method, and gave the following results during surgery: cefazolin--elimination half-life, 231 minutes, total body clearance, 1.05 mL/kg/min, and steady-state volume of distribution, 243 mL/kg. The values for netilmicin were 249 minutes, 1.18 mL/kg/min, and 353 mL/kg, respectively. Postoperatively there were no significant changes in the disposition of cefazolin, but the elimination half-life of netilmicin was shorter (124 minutes, P less than 0.01) and the total body clearance greater (3.58 mL/kg/min, P less than 0.01) than during surgery.

Adolescent↗

Renal failure and the use of morphine in intensive care.

Intravenous morphine infusions were given to 20 patients in the intensive-care unit to provide sedation and analgesia. In 10 of the patients renal impairment was already present or developed during intensive care. Plasma morphine concentrations for a given dose of morphine and morphine clearance depended on renal function; dose-related plasma morphine concentrations rose as renal function deteriorated. Reduced morphine clearance leads to increased elimination half-life of the drug, and neurological impairment caused by unrecognised high concentrations of morphine could result in an incorrect diagnosis of cerebral damage in patients in intensive care.

Adult↗

Morphine kinetics and kidney transplantation: morphine removal is influenced by renal ischemia.

Morphine plasma concentrations were determined in six patients receiving kidney transplants from living-related donors, and nine patients receiving kidney transplants from cadavers. The total cold ischemic time was about 2 hr for kidneys from living-related donors and 14 hr for those from cadavers. After an intravenous bolus dose of morphine, plasma morphine concentrations decreased to a plateau that lasted for several hours; morphine elimination resumed when the transplanted kidney began to clear creatinine. The duration of the total cold ischemic time was significantly related to both the duration of the plateau in morphine concentration (P = 0.008) and the first postoperative day creatinine clearance (P = 0.021). Morphine elimination half-life after the plateau was related to first postoperative day creatinine clearance (P less than 0.001). It was concluded that morphine elimination depended upon intact renal function.

Adult↗

Morphine kinetics during and after renal transplantation.

Plasma concentrations after intravenous morphine were measured by a specific radioimmunoassay method in patients undergoing renal transplantation and in control subjects. In both transplant patients and controls, plasma morphine fell in the first 10 min, but there was no significant further fall in the transplant patients until between 3 and 5 hr, when there was an abrupt reversion to the same elimination t1/2 as the controls. This coincided with recovery of renal function after the period of cold ischemia. In the transplant patients the AUC over 24 hr was higher and the plasma clearance was lower than in controls. The role of the kidney in morphine elimination is discussed.

Adult↗

Steroid anaesthesia.

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Alfaxalone Alfadolone Mixture↗