Plasma Leakage of Oxygenators in ECMO Depends on the Type of Oxygenator and on Patient Variables

This study was conducted to identify the causes of plasma leakage of oxygenators in extra corporeal membrane oxygenation (ECMO). From 1996 through 2002, 91 oxygenators were used in 62 patients undergoing ECMO for respiratory and/or cardiac failure. Several types of oxygenators were used (Medtronic Maxima, Minima, PRF, Medos Hilite). Patient variables and variables related to the ECMO set-up were analysed for their relationship with oxygenator failure by a time related multiple regression analysis (Cox).

Oxygenator failure occurred in 26% of the cases. The analysis identified the type of oxygenator (p=0.0016), younger patient age (p=0.04) and the number of oxygenators used (p=0.03) as the independent significant risk factors. The type of oxygenator used has the most overwhelming effect (significantly less leakage with the Medos Hilite).

In conclusion, leakage of oxygenators is predominantly caused by the type of oxygenator used. Patient variables (younger age and the number of oxygenators used in one patient) are also significant and allude to an inflammatory process as underlying mechanism of plasma leakage.

Selection Criteria and Outcome of Patients Referred to Intestinal Transplantation: An European Center Experience

Until 1998, intestinal transplantation (SBT) had not been performed in our region of Flanders, Belgium. Potential SBT activity was not known and selection criteria had not been validated. A multidisciplinary SBT program was launched in 1998. We analyzed requests for SBT and outcomes in these patients whether with or without SBT. Listing for SBT was only considered for patients with irreversible short bowel syndrome who had developed life-threatening complications of total parenteral nutrition, but whose general condition was still thought compatible with surgery and immunosuppression. During the study period 1998 to 2004, one third of the requests for SBT (10/31) were deemed suitable. SBT in this group was lifesaving (100% survival) when performed in time. Mortality in this group without SBT was high (67%). Two thirds of the patients (21/31) did not fulfill the SBT inclusion criteria, either because they were "too moribund" to tolerate transplantation or because they were "too well". This preliminary study emphasized the importance of (1) early referral of potential SBT candidates, (2) adherence to strict criteria for listing patients for SBT, and (3) referral of intestinal donors to procurement organizations.

Beta-adrenergic blocking drugs in the perioperative period

During the last years increasing evidence has indicated that patients at risk for coronary artery disease may benefit from beta-adrenergic blocking therapy in the perioperative setting. It has been demonstrated that even a relatively brief treatment with beta-adrenergic blocking drugs decreases the incidence of perioperative myocardial ischemia. Even more important is the observation that this reduction in perioperative ischemic events ultimately results in a decrease in long term cardiac morbidity and mortality. Despite overwhelming evidence on the beneficial effects of beta-adrenergic blocking in patients with coronary artery disease, many clinicians still feel some reluctance to use this type of drugs in the perioperative period. We organized a meeting to search for the major objectives that keep anesthetists from implementing prophylactic beta blocking therapy in their daily clinical practice. In this brief review we summarize the results of this meeting and discuss the current knowledge on this subject.

Intensive insulin therapy in critically ill patients

BACKGROUND

Hyperglycemia and insulin resistance are common in critically ill patients, even if they have not previously had diabetes. Whether the normalization of blood glucose levels with insulin therapy improves the prognosis for such patients is not known.

METHODS

We performed a prospective, randomized, controlled study involving adults admitted to our surgical intensive care unit who were receiving mechanical ventilation. On admission, patients were randomly assigned to receive intensive insulin therapy (maintenance of blood glucose at a level between 80 and 110 mg per deciliter [4.4 and 6.1 mmol per liter]) or conventional treatment (infusion of insulin only if the blood glucose level exceeded 215 mg per deciliter [11.9 mmol per liter] and maintenance of glucose at a level between 180 and 200 mg per deciliter [10.0 and 11.1 mmol per liter]).

RESULTS

At 12 months, with a total of 1548 patients enrolled, intensive insulin therapy reduced mortality during intensive care from 8.0 percent with conventional treatment to 4.6 percent (P<0.04, with adjustment for sequential analyses). The benefit of intensive insulin therapy was attributable to its effect on mortality among patients who remained in the intensive care unit for more than five days (20.2 percent with conventional treatment, as compared with 10.6 percent with intensive insulin therapy, P=0.005). The greatest reduction in mortality involved deaths due to multiple-organ failure with a proven septic focus. Intensive insulin therapy also reduced overall in-hospital mortality by 34 percent, bloodstream infections by 46 percent, acute renal failure requiring dialysis or hemofiltration by 41 percent, the median number of red-cell transfusions by 50 percent, and critical-illness polyneuropathy by 44 percent, and patients receiving intensive therapy were less likely to require prolonged mechanical ventilation and intensive care.

CONCLUSIONS

Intensive insulin therapy to maintain blood glucose at or below 110 mg per deciliter reduces morbidity and mortality among critically ill patients in the surgical intensive care unit.

Femoral venoarterial extracorporeal membrane oxygenation for severe reimplantation response after lung transplantation

Severe pulmonary reimplantation response after lung transplantation is not very common, although the mortality can be high. We present a patient who developed an extremely severe reperfusion injury after bilateral lung transplantation. Because of severe hypoxia and hemodynamic instability, despite aggressive ventilator settings, venoarterial extracorporeal membrane oxygenation (ECMO) was instituted using the femoral approach at the bedside. During ECMO, the patient developed a thoracic wall hematoma that was treated with transfusion alone. After 50 h of ECMO, his chest radiograph had dramatically improved, his oxygen need had been reduced to 50%, and he was successfully weaned from ECMO. Two years later, he is doing extremely well. Therefore, institution of ECMO using the femoral approach can be performed safely at the bedside in the ICU, and can be lifesaving in the context of a very severe reimplantation response after lung transplantation.

Pituitary responsiveness to GH-releasing hormone, GH-releasing peptide-2 and thyrotrophin-releasing hormone in critical illness

OBJECTIVE

Protein hypercatabolism and preservation of fat depots are hallmarks of critical illness, which is associated with blunted pulsatile GH secretion and low circulating IGF-I, TSH, T4 and T3. Repetitive TRH administration is known to reactivate the pituitary-thyroid axis and to evoke paradoxical GH release in critical illness. We further explored the hypothalamic-pituitary function in critical illness by examining the effects of GH-releasing hormone (GHRH) and/or GH-releasing peptide-2 (GHRP-2) and TRH administration.

PATIENTS AND DESIGN

Critically ill adults (n = 40; mean age 55 years) received two i.v. boluses with a 6-hour interval (0900 and 1500 h) within a cross-over design. Patients were randomized to receive consecutively placebo and GHRP-2 (n = 10), GHRH and GHRP-2 (n = 10), GHRP-2 and GHRH+GHRP-2 (n = 10), GHRH+GHRP-2 and GHRH+GHRP-2 + TRH (n = 10). The GHRH and GHRP-2 doses were 1 microgram/kg and the TRH dose was 200 micrograms. Blood samples were obtained before and 20, 40, 60 and 120 minutes after each injection.

MEASUREMENTS

Serum concentrations of GH, T4, T3, rT3, thyroid hormone binding globulin (TBG), IGF-I, insulin and cortisol were measured by RIA; PRL and TSH concentrations were determined by IRMA.

RESULTS

Critically ill patients presented a striking GH response to GHRP-2 (mean +/- SEM peak GH 51 +/- 9 micrograms/l in older patients and 102 +/- 26 micrograms/l in younger patients; P = 0.005 vs placebo). The mean GH response to GHRP-2 was more than fourfold higher than to GHRH (P = 0.007). In turn, the mean GH response to GHRH+GHRP-2 was 2.5-fold higher than to GHRP-2 alone (P = 0.01), indicating synergism. Adding TRH to the GHRH+GHRP-2 combination slightly blunted this mean response by 18% (P = 0.01). GHRP-2 had no effect on serum TSH concentrations whereas both GHRH and GHRH+GHRP-2 evoked an increase in peak TSH levels of 53 and 32% respectively. The addition of TRH further increased this TSH response > ninefold (P = 0.005), elicited a 60% rise in serum T3 (P = 0.01) and an 18% increase in T4 (P = 0.005) levels, without altering rT3 or TBG levels. GHRH and/or GHRP-2 induced a small increase in serum PRL levels. The addition of TRH magnified the PRL response 2.4-fold (P = 0.007). GHRP-2 increased basal serum cortisol levels (531 +/- 29 nmol/l) by 35% (P = 0.02); GHRH provoked no additional response, but adding TRH further increased the cortisol response by 20% (P = 0.05).

CONCLUSIONS

The specific character of hypothalamic-pituitary function in critical illness is herewith extended to the responsiveness to GHRH and/or GHRP-2 and TRH. The observation of striking bursts of GH secretion elicited by GHRP-2 and particularly by GHRH+GHRP-2 in patients with low spontaneous GH peaks opens the possibility of therapeutic perspectives for GH secretagogues in critical care medicine.

Thyrotropin-releasing hormone in critical illness: from a dopamine-dependent test to a strategy for increasing low serum triiodothyronine, prolactin, and growth hormone concentrations

OBJECTIVE

The aim of this study was to examine the effect of dopamine infusion on the thyrotropin (TSH), thyroid hormone, prolactin, and growth hormone responses to thyrotropin-releasing hormone (TRH) in critically ill patients.

DESIGN

Prospective, randomized, controlled, open-labeled clinical study.

SETTING

The intensive care unit, University Hospital Gasthuisberg, Leuven, over a 1-month period.

PATIENTS AND INTERVENTIONS

In 15 critically ill patients receiving dopamine treatment (5 micrograms/kg/min) for a mean of 43.3 +/- 1.2 (SEM) hrs after trauma or cardiac surgery, we studied the TSH, thyroid hormone, prolactin, and growth hormone responses to the administration of two consecutive intravenous TRH boluses of 200 micrograms, with a 6-hr interval. The dopamine infusion was continued in the control group and discontinued in the study group. Serum concentrations of TSH, prolactin, and growth hormone were measured before and 20, 40, 60, and 120 mins after TRH administration. Serum concentrations of thyroxine (T4), triiodothyronine (T3), reverse T3, and thyroid hormone binding globulin were determined before and 120 mins after each TRH injection.

MEASUREMENTS AND MAIN RESULTS

There was a > 100-fold interindividual variation in the baseline TSH concentration and in the TSH peak value after TRH administration. Two consecutive doses of TRH evoked a mean 16% increase in serum T4 concentration (p = .003) and a mean 47% increase in T3 (p = .001), whereas serum reverse T3 and thyroid hormone binding globulin values remain unaltered. Each of the TRH boluses increased serum growth hormone concentrations in the continued dopamine and discontinued dopamine groups, by a median of 60% (p = .001) and 68% (p = .001), respectively. Three hours after dopamine withdrawal, there was a three-fold increase of the peak TSH response (p = .001), a higher T3 response (p = .01), and a ten-fold increase of the peak prolactin value (p = .001) in response to TRH administration.

CONCLUSIONS

The TSH response to TRH administration in critical illness presents a striking interindividual variation and dopamine dependent. Repeated TRH administration results in a repetitive increase of TSH, prolactin, growth hormone, T4, and T3, without increasing reverse T3. These observations point toward a potential for TRH as a strategy for reversing the euthyroid sick syndrome, growth hormone deficiency, and immune dysfunction associated with critical illness.