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Biomedical subjects

G Parkin

Publications and source records attributed to G Parkin.

At least 37 records · Page 2Linked to original sources
PubMed1994

Use of a mean systemic filling pressure analogue during the closed-loop control of fluid replacement in continuous hemodiafiltration.

PURPOSE: To assess the use and validity of a mean systemic filling pressure analogue (Pmsa) in the closed-loop control of fluid replacement in continuous hemodiafiltration. METHODS: Cardiovascular variables were computer acquired from bedside monitor. Pmsa was calculated and compared with a target value. Gravitational fluid replacement to the extracorporeal hemodiafiltration circuit was regulated with a computer-controlled clamp. RESULTS: Ten patients (mean acute physiology and chronic health evaluation II score, 29.7; range, 21-33) received continuous venovenous hemodiafiltration for acute renal failure. Fluid replacement therapy was closed loop controlled to a target Pmsa for a total of 601 hours. During this period, 417 L of ultradiafiltrate were lost, and 409 L of replacement and nutritional fluids were administered. Despite such large fluid shifts, measured hemodynamic variables were kept within a narrow range (hour to hour variability: right atrial pressure, 1 +/- 0.1 mm Hg; mean arterial pressure 5.9 +/- 0.5 mm Hg; cardiac index, 0.44 +/- 0.05 L/m2/min). No complications of the technique occurred. CONCLUSIONS: The stability of cardiovascular variables achieved during Pmsa-based fluid replacement of critically ill patients with major fluid losses supports the validity of the use of the Pmsa as a measure of intravascular volume status. Such an analogue may be useful in nondialytic environments. The use of Pmsa as the basis for automated fluid replacement was safe.

Acute Kidney Injury↗
PubMed1994

Asthma requiring mechanical ventilation. A low morbidity approach.

STUDY OBJECTIVE: There is considerable uncertainty about the clinical features, respiratory physiology, and optimal management of patients with asthma requiring mechanical ventilation. Furthermore, the ventilatory and pharmacologic management of asthma requiring mechanical ventilation remain controversial. We hypothesized (1) that there are clinically identifiable and pathophysiologically different subgroups presenting with asthma requiring ventilation; (2) that lower dose steroid therapy (< 400 mg/d intravenous hydrocortisone) is adequate; (3) that permissive hypercapnia is safe; (4) that prolonged paralysis is generally unnecessary; and (5) that clinical outcome would be favorable in patients treated with this approach. DESIGN: Review of medical records and intensive care charts and statistical analysis of findings. SETTING: ICU of tertiary institution. PATIENTS: Thirty-five consecutive cases of life-threatening asthma requiring mechanic ventilation. RESULTS: Three clinical subgroups of ventilation-requiring asthmatics could be identified. Those presenting with steady deterioration (10), those with unstable asthma followed by a sudden "dip" (16), and those with a sudden unexpected dip (9). Patients in the first group had a significantly lower PaCO2 (p < 0.01) at presentation, but required ventilation for longer periods. Those in the second group had a significantly higher PaCO2 (p < 0.01) and required ventilation for a shorter period. Those in the third group had an intermediate PaCO2 level before intubation and the shortest period (p < 0.01) of mechanical ventilation. Five patients experienced their sudden dip after ingesting aspirin. Ten cases received "high" dose hydrocortisone therapy (mean: 980 mg/24 h), and 25 received lower dose hydrocortisone (mean: 341 mg/24 h). No differences in illness severity at presentation or outcome could be detected between these two groups. Mean duration of ventilatory support was 36 h and mean duration of the ICU stay 52.1 h. Muscle relaxation was used in 12 patients for a mean period of 11.1 h. One patient was brain dead on arrival. All others survived. CONCLUSIONS: Life threatening asthma is an endpoint for several different clinical patterns of disease. No major clinical advantage could be found in our group of patients when high-dose steroids were used. Long-term use of muscle relaxants and prolonged mechanic ventilation are rarely needed in the management of patients with life-threatening asthma and excellent results can be achieved with a relatively simple management strategy.

Adult↗
PubMed1993

Acute renal failure in the critically ill: management by continuous veno-venous hemodiafiltration.

The consequences of newer techniques of continuous renal replacement therapy in critically ill patients are not yet fully known. The clinical and biochemical impact of continuous veno-venous hemodiafiltration (CVVHD) was, therefore, prospectively studied in 60 critically ill patients with acute renal failure. Prospective clinical, biochemical, and hematological data were collected from patients receiving CVVHD. Over the initial 24 hours of therapy, CVVHD resulted in a decrease in mean plasma urea from 34.5 mmol/L (95% confidence interval [CI], 29.4 to 39.6) to 25 mmol/L (95% CI, 21.8 to 28.2). With continued CVVHD, the mean plasma urea reached a plateau level of 17.6 mmol/L (95% CI, 15.8 to 19.4) at 72 hours. This degree of azotemia control was achieved with ease and essentially without complications during 8,360 hours of therapy despite the presence of multi-organ failure and the aggressive administration of protein nitrogen (0.25 to 0.35 g/kg/day). No abnormalities of serum electrolytes developed during treatment. Survival to intensive care discharge was 46.6% and to hospital discharge 41.6%, despite a mean Acute Physiology and Chronic Health Evaluation (APACHE) II score at presentation of 27.7. Continuous veno-venous hemodiafiltration offers superior azotemia control and a safe approach to renal replacement therapy in critically ill patients. Its use is associated with a comparatively favorable outcome. CVVHD may be regarded as the treatment of choice in such patients.

Acute Kidney Injury↗
PubMed1993

A prospective comparative study of continuous arteriovenous hemodiafiltration and continuous venovenous hemodiafiltration in critically ill patients.

We have prospectively studied and compared two consecutive groups of critically ill patients treated with either continuous arteriovenous hemodiafiltration (CAVHD) (n = 28) or continuous venovenous hemodiafiltration (CVVHD) (n = 25) to establish the technique of choice. The two groups were comparable in mean age (59 v 58 years), mean Acute Physiology and Chronic Health Evaluation (APACHE) II score (29.6 v 27.4, P = NS), requirements for inotropic drugs, and mean number of failing organs (2.9 v 3.2). CVVHD led to a greater amount of hourly ultrafiltrate (mean, 590 v 424 mL; P < 0.001), but urea and creatinine clearances were not significantly different with the two techniques. Twelve patients survived in the CAVHD group (42.8%) and 13 in the CVVHD group (52%; P = NS). The major advantage for CVVHD use was the substantial decrease in the number of access-related complications (2 v 10; P < 0.025). We conclude that while CVVHD does not offer a significant increase in solute clearance, it significantly minimizes vascular access-related morbidity and should therefore be regarded as the therapeutic modality of choice.

Chi-Square Distribution↗
PubMed1993

A comparison of conventional dialytic therapy and acute continuous hemodiafiltration in the management of acute renal failure in the critically ill.

OBJECTIVE: To compare and contrast the clinical outcomes in critically ill patients with acute renal failure managed with either acute continuous hemodiafiltration or conventional dialytic therapies. DESIGN: Retrospective review of the medical records of 167 consecutive cases of acute renal failure treated at a single center (July 1982-July 1991). Scoring for illness severity (APACHE II, number of failing organs) and assessment of outcome in terms of biochemical control of azotemia, ARF therapy-related morbidity, and overall morbidity and mortality. SETTING: Tertiary institution. PATIENTS: 167 consecutive critically ill patients with multiorgan failure and acute renal failure. MEASUREMENTS AND MAIN RESULTS: 84 patients received conventional dialytic therapy (CDT) (1982-1988) and 83 acute continuous hemodiafiltration (ACHD) (1988-1991). The etiology of ARF and illness severity indices were similar in both groups (organ failure scores: CDT 3.9 vs. ACHD 4.1; NS). All patients were critically ill, with more severely ill patients within the ACHD groups (mean APACHE II score: CDT 25.8 vs. ACHD 28.1; p < .01). There were no significant differences in pretreatment serum creatinine, glucose, bicarbonate and phosphate, white cell and platelet counts, incidence of disseminated intravascular coagulation, prevalence of sepsis, or evidence of pulmonary and/or peripheral edema. Overall survival was 29.8% for the CDT groups and 41% for the ACHD group (NS). When patients were stratified by severity of illness, survival in those with 2 to 4 failing organs was significantly greater in the ACHD group (CDT 31.1% vs. ACHD 53.8%; p < .025). Similarly, overall survival in patients with intermediate APACHE II scores (24 to 29) was significantly better in those treated with ACHD (CDT 12.5% vs. ACHD 46.4%; p < .025). During the course of ARF, in comparison to CDT, ACHD was associated with greater overall reductions in serum creatinine, and in phosphate and plasma urea, and an increased net nutritional intake. CONCLUSIONS: ACHD provided biochemical and outcome indicator advantages over conventional dialytic therapy. In patients with 2 to 4 failing organs or an intermediate APACHE II score (24 to 29) a significant survival advantage was demonstrated for ACHD over CDT. Although this study is a retrospective analysis, with all the inherent limitations of such studies, it suggests that ACHD is the treatment of choice for ARF in the critically ill, with maximum benefits seen in those with 2 to 4 failing organs and/or intermediate APACHE II scores.

Acute Kidney Injury↗
PubMed1992

Use of continuous haemodiafiltration: an approach to the management of acute renal failure in the critically ill.

We have prospectively investigated the effect of a flexible approach to the management of acute renal failure in critically ill patients based on continuous haemodiafiltration (CHD). Fifty critically ill patients (mean APACHE II score 28.1, range 18-37), with a mean age of 59.5 years, were treated with continuous arteriovenous haemodiafiltration (CAVHD) and/or continuous venovenous haemodiafiltration (CVVHD). CHD achieved excellent haemodynamic stability and control of azotaemia in all patients and permitted aggressive parenteral nutrition. The mean blood urea concentration fell from 33.9 mmol/l (95% confidence interval, CI, 29.1-38.7) to a plateau of 17 mmol/l (95% CI 14.3-19.7) after 72 h of therapy despite persistent anuria and the parenteral administration of 0.3 g/kday of protein nitrogen (mean urea clearance: 24.2 ml/min; 95% CI 22.9-25.5). No supplemental dialytic therapy was required during the 9,485 h of treatment. All clinically significant complications related to vascular access (14%). Twenty-two patients (44%) survived to be discharged from the ICU. CHD is relatively safe and effective in the management of acute renal failure in the critically ill.

Acute Kidney Injury↗
PubMed1992

Fibreoptic bronchoscopy in the critically ill: a prospective study of its diagnostic and therapeutic value.

AIM: A prospective study was undertaken to assess the diagnostic value and therapeutic usefulness of fibreoptic bronchoscopy in the critically ill. METHOD: Fifty-six bronchoscopies were performed in fifty patients. Biochemical, radiological, microbiological and clinical assessments were made before and after each procedure. RESULTS: Eighteen fibreoptic bronchoscopies were performed for therapeutic indications (32.1%) of which ten (55.6%) yielded a useful outcome. Thirty-eight bronchoscopies were for diagnostic purposes (67.8%) of which 22 (57.9%) were clinically useful. Broncho-alveolar lavage was performed in twenty-eight cases (50%) and it led to a clinically useful diagnosis in 17 (60.7%). There was no major complication. A subgroup of patients was defined (persistent left lower lobe collapse or consolidation following thoracic or abdominal surgery) in whom fibreoptic bronchoscopy usually did not yield a useful outcome. CONCLUSION: The use of fibreoptic bronchoscopy in the Intensive Care Unit, in combination with the technique of broncho-alveolar lavage, results in a clinically useful outcome in the majority of cases. Fibreoptic bronchoscopy is an effective and safe diagnostic and therapeutic tool in critically ill patients.

Adolescent↗
PubMed1992

Management of acute renal failure in the critically ill with continuous venovenous hemodiafiltration.

Continuous venovenous hemodiafiltration (CVVHD) has been increasingly utilized for renal replacement therapy in the critically ill. We report details of a prospective study of CVVHD in 12 critically ill patients (7 males, 5 females; mean age 60 years, range 30-72 years; Apache II score mean 27.4, range 21-35) with oligoanuric acute renal failure supported on CVVHD. Vascular access was obtained via double lumen subclavian or femoral cannulae. The mean pretreatment urea was 35.9 mM/L and the mean pretreatment creatinine was 559 microM/L. After 24 h of treatment on CVVHD these fell to a urea mean of 20.3 mM/L and a creatinine mean of 298 microM/L and remained stable at these values for the duration of CVVHD. The mean net ultrafiltrate volume was 551 mL/h, with a urea clearance mean of 26.6 mL/min and a creatinine clearance mean of 23.7 mL/min. There were no complications related to use of the blood pump module or extracorporeal circuit. Excellent hemodynamic stability, control of fluid and electrolyte balance, and azotaemia control were maintained while on CVVHD. Technique survival was 100%. Patient survival was 42%. We conclude that CVVHD is a safe, effective, and durable therapy for the treatment of acute renal failure in the critically ill and that it offers outstanding metabolic control and cardiovascular stability.

Acute Kidney Injury↗
PubMed1991

Continuous arteriovenous haemodiafiltration in the critically ill: influence on major nutrient balances.

The impact of continuous arteriovenous haemodiafiltration (CAVHD) on nitrogen, lipid and carbohydrate balance was studied in 9 parenterally fed critically ill patients with acute renal failure. The effects on carbohydrate delivery of varying dialysate glucose concentrations or flow rates were also investigated. The total daily nitrogen loss was a mean of 24.1 g (95% CI 20.9-27.3 g/24 h) with non-urea nitrogen losses of 7.6 g (95% CI 5.6-9.6 g/24 h). Glucose delivery was a mean 5.8 g/h with a dialysate glucose concentration of 1.5% and a flow rate of 1 l/h (95% CI 4.5-7.0 g/h). Carbohydrate delivery increased with increased dialysate glucose concentration (mean 11.4 g/h with 2.5% glucose: 95% CI 9.6-13.1 g/h; mean 14.9 g/h with a 4.25% concentration: 95% CI 10.9-19; and with increased dialysate flow rates (mean 9.6 g/h, 95% CI 6.8-12.4 g/h, using 2 l/h of 1.5% glucose). Only trace amounts of cholesterol and/or triglycerides were detected in occasional ultradiafiltrate samples. CAVHD has an important impact on nitrogen and carbohydrate balance, but not on lipid status. Knowledge of these interactions is crucial for the rational planning of nutritional strategies in the critically ill.

Acute Kidney Injury↗
PubMed1990

Clearance of vancomycin during continuous arteriovenous hemodiafiltration.

The clearance of vancomycin during therapy with continuous arteriovenous hemodiafiltration (CAVHD) has been measured in vivo. Vancomycin clearances (n = 16) were 0.636 +/- 0.269 L/h (10.5 +/- 4.46 ml/min). Effective drug clearances were proportional to ultrafiltrate volumes, reflecting convective clearance. Clearances of vancomycin on CAVHD were approximately twice the values seen with continuous arteriovenous hemofiltration. These data allow construction of a dosing schedule for vancomycin therapy in patients receiving renal support via CAVHD.

Acute Kidney Injury↗
PubMed1990

Continuous arteriovenous haemodiafiltration: optimal therapy for acute renal failure in an intensive care setting?

We report the results of continuous arteriovenous haemodiafiltration (CAVHD) treatment in 12 critically ill intensive care patients with acute renal failure (eight males, four females - mean age 60.9 years - range 47 to 76) (APACHE II score 28.8, range 18-37). All patients were oligoanuric or had a rising creatinine (greater than or equal to 100 microM/L per day). Vascular access was obtained by Scribner shunt or wide-bore femoral arterial and venous cannulae. At the beginning of CAVHD therapy the mean plasma urea was 38 mM/L (SE 4.5, 95% confidence interval (CI) 25.1 to 75.6 mM/L) and the mean creatinine was 604 microM/L (SE 70, 95% CI 450-756 microM/L). After 72 hours of therapy, despite oligoanuria, urea concentration had fallen to a mean of 15.7 mM/L (SE 2.4, 95% CI 12.5-22.9 mM/L) and the creatinine concentration to 297 microM/L (SE 25, 95% CI 243-351 microM/L), respectively. The mean ultrafiltrate volume was 441 mL/hr (SE 33, 95%, range 50-1050 mL/hr). There were no complications related to the extracorporeal circuit, the filter, anticoagulant therapy, electrolyte status or changes in patients' haemodynamic state. Excellent biochemical control of azotaemia was uniformly achieved during CAVHD therapy. Five patients (41.6%) survived to be discharged from the Intensive Care Unit. CAVHD is a simple, safe and effective continuous renal replacement therapy. CAVHD offers technical advantages over alternative therapy while providing equivalent or better biochemical control of azotaemia and volume status in critically ill patients with acute renal failure.

Acute Kidney Injury↗