The need for assessment of sedation in the critically ill

There is a need for assessment of sedation in ICU as sedative agents are potent drugs that are used frequently but not regularly monitored for their efficacy. Critical care nurses are accountable when administering potent intravenous drugs, such as sedative agents. This paper examines the rationale behind the use of sedation in ICU. A number of sedative drugs commonly used in ICU, such as propofol, are highlighted. Sedation assessment tools available are considered but each may be appropriate in different situations.     

Reversing oliguria in critically ill patients

Oliguria is a common occurrence in the ICU setting. In patients with preserved renal function, fluid challenges or low doses of diuretics are generally successful. In patients with oliguric renal failure, it is still essential to ensure adequate intravascular fluid volume, especially in critically ill patients. Loop diuretics remain the mainstay of treatment. When diuretic resistance is encountered, physicians should consider further optimization of hemodynamics, alternative loop diuretics, and combined drug therapy. In some cases, continuous renal replacement therapy can be very effective. Yet, while these interventions can help reduce the morbidity of severe volume overload, they have not been shown to improve mortality rates.     

Nutritional support of critically ill patients

Severe depletion of body protein stores can result from prolonged starvation or from hormonal and cytokine-mediated effects during critical illness. Recent advances in the understanding of cytokine actions have substantially refined the interpretation of the nutritional assessment of critically ill patients. In addition, the design of nutritional programs for hospitalized patients has changed considerably during the past decade. Although nutritional support of critically ill patients will not lead to positive nitrogen balance, nutrition can increase protein synthesis, enhance immune function, and beneficially modify the body's response to an illness.     

Use of in vitro models of haemofiltration and haemodiafiltration to estimate dosage regimens for critically ill patients prescribed cefpirome

Membrane oxygenators have now gained wide acceptance. A new hollow-fibre membrane oxygenator, the Dideco D903 Avant 1.7, with an optimized membrane surface (1.7 m2) and a wavy blood flow pattern, was tested for gas transfer and blood path resistance in a standardized setting with surviving animals. Three calves (mean body weight 63.29 +/- 2.9 kg) were connected to cardiopulmonary bypass by jugular venous and carotid arterial cannulation, classic roller pump and the Dideco D903 oxygenator with a mean flow rate of 53 +/- 0.1 ml/kg/min for 6 h. After this time, the animals were weaned from the CPB and thereafter from the ventilator. After 7 days, the animals were killed electively. Blood gas analysis was performed before bypass, after mixing (10 min) and then hourly for the 6 h of perfusion. Further samples were taken 30 min (spontaneous breathing) and 60 min after bypass (extubated). Physiological blood gas values could be maintained throughout perfusion in all animals. Mean arterial oxygen saturation varied between 99.3% and 99.7% for the arterial side of the oxygenator compared to 64.6% and 71% for the venous side. The highest mean pressure drop through the oxygenator was 54 mmHg. Postbypass blood gas analysis showed physiological values and no evidence of major lung trauma or pulmonary oedema in relation to the 6 h perfusion. The hollow-fibre membrane oxygenator, Dideco D903, offers excellent gas exchange capabilities and a low pressure drop under experimental conditions, despite reduced membrane surface area. The post mortem examination did not show any deleterious lesion.     

Human growth hormone kinetics in critically ill patients

Several studies have shown that exogenous human growth hormone (HGH) exerts an anabolic effect on protein metabolism in surgical patients with mild or moderate catabolism. However, contradictory results have been demonstrated in polytrauma patients where HGH did not improve protein metabolism. Aim of this study was to evaluate whether the pharmacokinetics of recombinant biosynthetic human GH (r-HGH) are altered in critically ill patients. After an overnight fast, r-HGH was infused at a rate of 460 micrograms/h/kg/bw during 120 min to five intensive care unit (ICU) patients. The patients were catabolic (nitrogen balance -11 +/- 0.5), showed normal liver function, and only one patient had a slightly impaired kidney function (creatinine > 1.5 mg/dl). Endogenous GH secretion was suppressed by continuous infusion of 50 micrograms/m2/h somatostatin. From plasma GH curves, elimination half life (t1/2kle), whole body clearance (Cltot) and steady state distribution space (DS) were calculated in an open two compartment model. Additionally, the effects of r-HGH infusion on plasma insulin, glucagon and amino acid concentrations were evaluated. T1/2kle was 19.6 +/- 2.3 min, Cltot 2.9 +/- 0.4 ml/kg/bw/min and DS 76.4 +/- 3.8 ml/kg/bw for 90 min. The plasma levels of total amino acids including the branched chain amino acids valine, leucine and isoleucine and of glutamine were significantly higher during r-HGH infusion than during the basal and somatostatin periods. In conclusion, the elimination of r-HGH in catabolic ICU patients is not different from that of healthy volunteers.     

Predictability of creatinine clearance estimates in critically ill patients

OBJECTIVES: a) To evaluate the predictive ability of different creatinine clearance methods as compared with the criterion standard, inulin clearance; and b) to determine which of the predictive methods yields the most accurate estimation of creatinine clearance. DESIGN: Prospective study. SETTING: Medical intensive care unit (ICU) of a university-affiliated tertiary care hospital. INTERVENTIONS: Glomerular filtration rate was measured by the criterion standard, inulin clearance. PATIENTS: Twenty mechanically ventilated adults. MEASUREMENTS: Renal function was assessed by the following procedures: inulin clearance using a standard protocol, 30-min creatinine clearance, 24-hr creatinine clearance, and creatinine clearance estimates by the Cockcroft-Gault equation. Ideal body weight, total body weight or lean body mass with actual serum creatinine or serum creatinine concentration corrected to 1 mg/dL (85 mumol/L) in cachectic patients were sequentially incorporated into the Cockcroft-Gault equation. RESULTS: The Cockcroft-Gault equation, using ideal body weight and the corrected serum creatinine concentration, was the best predictor of inulin clearance with the smallest bias (9.7 +/- 8.6, 95% confidence interval 5.7 to 13.8). The bias encountered with the 30-min creatinine clearance was not different from that value with the 24-hr creatinine clearance (21.6 +/- 33.0, 95% confidence interval 6.2 to 37.1 vs. 25.4 +/- 28.3, 95% confidence interval 11.8 to 42.9). Good correlations existed between inulin clearance and the Cockcroft-Gault equation, using ideal body weight and the corrected serum creatinine concentration (r2 = .81; p = .0001), as well as between inulin clearance and the Cockcroft-Gault equation, using the lower of ideal or total body weight and the higher of the actual serum creatinine concentration or corrected serum creatinine (r2 = .75; p = .0001). The 30-min creatinine clearance and the 24-hr creatinine clearance had poorer agreement with inulin clearance. The incorporation of a corrected serum creatinine value into the Cockcroft-Gault equation consistently led to better predictions and higher correlation coefficients. CONCLUSIONS: The utilization of the Cockcroft-Gault equation as used clinically (the lower of ideal or total body weight and the higher of actual serum creatinine or corrected serum creatinine concentration to 1 mg/dL [85 mumol/L]) results in more accurate predictions of glomerular filtration rate in the medical, critically ill patient than urine creatinine clearance measures. If creatinine clearance measures are used, the 30-min collection provided results not different from those results obtained with 24-hr urinary collections.     

Bone hyperresorption is prevalent in chronically critically ill patients

STUDY OBJECTIVE: Chronically critically ill (CCI) patients are primarily elderly people who have survived a life-threatening episode of sepsis but remain profoundly debilitated and ventilator dependent. The objective of this study was to determine the prevalence of bone hyperresorption and parathyroid hormone (PTH)-vitamin D axis abnormalities in these patients. DESIGN: Prevalence survey. SETTING: Respiratory care step-down unit (RCU) at a tertiary care teaching hospital. PATIENTS: Forty-nine ventilator-dependent CCI patients transferred from ICUs within the same institution. INTERVENTION: None. MEASUREMENTS AND RESULTS: N-telopeptide (NTx) levels in 24-h urine collections and serum intact PTH, 25-vitamin D, and 1,25-vitamin D levels were measured within 48 h of RCU admission. Patients were hospitalized a median of 30 days before RCU admission. Four patients (9%) had normal NTx and PTH levels. Forty-five patients (92%) had elevated urine NTx levels consistent with bone hyperresorption. Nineteen patients (42% of total patients) had elevated PTH levels consistent with predominant vitamin D deficiency, 4 patients (9%) had suppressed PTH levels consistent with predominant hyperresorption from immobilization, and 22 patients (49%) had normal PTH levels consistent with an overlap of both vitamin D deficiency and immobilization. There were no differences in vitamin D metabolites among these groups. CONCLUSIONS: CCI patients have a high prevalence of bone hyperresorption in which PTH levels may clarify the cause. Further studies will determine the efficacy and cost-effectiveness of routine NTx and PTH screening in these patients and the role of vitamin D and antiresorptive therapies.     

Pharmacokinetics and pharmacodynamics of bumetanide in critically ill pediatric patients

This prospective, open-label, clinical trial was conducted to describe the pharmacology of bumetanide in pediatric patients with edema. Nine infants, children, and young adults with edema who were selected for diuretic therapy were studied. After a brief baseline period, each patient received parenteral bumetanide 0.2 mg/kg divided into two equal doses and administered every 12 hours. Urine excretion rate, fractional and total excretion of Na+, Cl-, and K+, creatinine clearance, and plasma and urine concentrations of bumetanide were measured at multiple intervals after drug administration. Bumetanide caused significant increases in the excretion rate of urine and each measured electrolyte. Unexpectedly, creatinine clearance increased dramatically after each dose. Adverse effects, including hypokalemia and hypochloremic metabolic alkalosis, were evident by the end of the treatment period. The plasma pharmacokinetics of bumetanide revealed mean +/- standard deviation values for total clearance and apparent volume of distribution of 3.9 +/- 2.4 mL/min/kg and 0.74 +/- 0.54 L/kg, respectively. Patients excreted an average of 34% of each dose unchanged in the urine over 12 hours. Plasma concentrations of bumetanide accurately predicted several renal effects using a link model with similar pharmacodynamic parameters in each case. Parenteral bumetanide 0.1 mg/kg administered every 12 hours produced significant beneficial and adverse effects in these critically ill pediatric patients with edema. Pharmacokinetic parameters are similar to those previously reported for infants. Plasma concentrations of bumetanide can predict effect-compartment pharmacodynamics.     

Impaired gastric emptying in mechanically ventilated, critically ill patients

OBJECTIVE: To measure gastric emptying in critically ill patients using an acetaminophen absorption model and determine which variables are associated with impaired gastric emptying. DESIGN: A prospective, cohort study. SETTING: A medical/surgical ICU at a tertiary care hospital: Hamilton General Hospital, Hamilton, Ontario. PATIENTS AND PARTICIPANTS: We recruited 72 mechanically ventilated patients expected to remain in the ICU for more than 48 h. Our results were compared to those in healthy volunteers. INTERVENTION: Within 48 h of admission to the ICU, 1.6 g acetaminophen suspension were administered via a nasogastric tube into the stomach. Blood samples were drawn a t = 0, 30, 60, 90, and 120 min for measurement of plasma acetaminophen levels determined by the enzymatic degradation method. MEASUREMENTS AND RESULTS: Maximal concentration of acetaminophen was 94.1 (75.3) mumol/l compared to 208.4 (33.1) mumol/l in a control population (p < 0.0001). The time to reach the maximal concentration was 105 min (60-180) compared to 30 min (15-90) in controls (p < 0.0001). The area under the time-acetaminophen concentration curve t = 120 was 9301 (7343) mumol/min per l compared to 11644 (1336) mumol/min per l in the controls (p = 0.28). The variables associated with delayed gastric emptying were age, sex and use of opioids for analgesia and sedation. CONCLUSIONS: Gastric emptying is delayed in critically ill patients. The important consequences of this phenomenon include intolerance to enteral nutrition and gastric colonization. Strategies to minimize the use of narcotics may improve gastric emptying. Studies to examine the effect of gastrointestinal prokinetic agents on gastric emptying are needed.     

Concealed lung abscess in critically ill, mechanically ventilated patients

This article reports on phenomenological research designed to discover how caring was taught in a nursing education program. The basic questions were: 1) What is the meaning of caring to the faculty and students; 2) How do the faculty communicate this meaning to the students; and 3) How does this meaning shape the experience of the students? Data were collected from a small associate degree nursing program using: a) semi-structured interviews with all faculty and a selected group of students, b) classroom observations, and c) review of documents. Data were analyzed for and found to have content explaining the meaning of caring, how caring was being taught, and what students were learning about caring as the essence of nursing. Implications derived speak to the need for faculty and administrators to have caring as a way of being if they wish to communicate caring as the essence of nursing to students.     

Usefulness of transesophageal echocardiography in the treatment of critically ill patients

To evaluate the usefulness of transesophageal echocardiography (TEE) in the treatment of critically ill patients, 80 patients (51 male and 29 female; mean age, 53 years) undergoing both transthoracic echocardiography (TTE) and TEE were studied in a 2-year period. Of these, 48 patients were studied in the ICU, while the other 32 patients were directly referred from the emergency departments. Indications for the study included suspected aortic dissection (34 patients), hemodynamic instability (22 patients), suspected cardiac source of embolism (11 patients), evaluation of the severity of mitral regurgitation (7 patients), and suspected infective endocarditis (6 patients). The probe was passed successfully in 78 of 80 attempts (98 percent). No significant complications were recorded during the transesophageal echocardiographic study. Transesophageal echocardiography provided critical information that was not obtained by TTE in 39 of 78 studies (50 percent, p < 0.005). Cardiac surgery was prompted by TEE findings in 14 patients (18 percent) and these findings were all confirmed at operation. Transesophageal echocardiography was a safe, well-tolerated, and valuable diagnostic approach for the rapid detection of specific cardiac abnormalities in patients with critical illness; TEE should be considered in the treatment of critically ill patients especially when TTE provided inadequate information.