Relationship of blood thiamine pyrophosphate to plasma phosphate and the response to enteral nutrition plus co-administration of intravenous thiamine during critical illness.

BACKGROUND: Hypovitamin B1 occurs frequently during critical illness but is challenging to predict or rapidly diagnose. The aim of this study was to evaluate whether plasma phosphate concentrations predict hypovitamin B1, enteral nutrition prevents hypovitamin B1 and intravenous thiamine supplementation achieves supraphysiological concentrations in critically ill patients. METHODS: Thirty-two enterally fed critically ill patients, with a plasma phosphate concentration ≤0.65 mmol/L, formed a nested cohort within a larger randomised clinical trial. Patients were assigned to receive intravenous thiamine (200 mg) twice daily, and controls were not administered intravenous thiamine. Thiamine pyrophosphate concentrations were measured at four time points (pre- and post-infusion and 4- and 6-h post-infusion) on days 1 and 3 in those allocated to thiamine and once in the control group. RESULTS: Baseline thiamine pyrophosphate concentrations were similar (intervention 88 [67, 93] vs. control 89 [62, 110] nmol/L, p = 0.49). Eight (25%) patients had hypovitamin B1 (intervention 3 vs. control 5), with two patients in the control group remaining insufficient at day 3. There was no association between baseline phosphate and thiamine pyrophosphate concentrations. Intravenous thiamine achieved supraphysiological concentrations 6 h post first infusion, with concentrations increasing to day 3. In the control group, thiamine pyrophosphate concentrations were not statistically different between baseline and day 3 (mean change: 8.6 [-6.0, 23.1] nmol/L, p = 0.25). CONCLUSIONS: Phosphate concentrations did not predict hypovitamin B1, which was observed in 25% of the participants. Enteral nutrition alone prevented the development of new hypovitamin B1. Administration of a single 200-mg dose of intravenous thiamine achieved supraphysiological concentrations of thiamine pyrophosphate, with repeated dosing sustaining this effect.

The hospital-based evaluation of laxative prophylaxis in ICU (HELP-ICU): A pilot cluster-crossover randomized clinical trial.

PURPOSE: Prophylactic laxative regimens may prevent constipation but may increase diarrhea and subsequent rectal tube insertion. Our aim was to compare three prophylactic laxative regimens on the rate of rectal tube insertion (primary outcome) and major constipation- or diarrhea-associated complications. MATERIAL AND METHODS: We conducted a cluster-crossover trial. Three pods in a single ICU were each randomized to one of three regimens for four months with rolling cross-over. All mechanically-ventilated and enterally-fed adult patients received either regimen: A) one coloxyl with senna BD from day one; B) two coloxyl with senna +20 ml lactulose BD commencing on day 3; or C) two coloxyl with senna tablets +20 ml lactulose BD commencing on day 6. RESULTS: We enrolled 570 patients (A = 170, B = 205, C = 195) with similar baseline features. Overall, 53 (9.3%) patients received a rectal tube, and insertion rate was not statistically different between the three regimens (A = 12.9%, B = 7.8%, C = 7.7%; p = 0.15). The proportions of patients with other major constipation- or diarrhea-associated complications were similar, as were major patient-centred outcomes. CONCLUSION: Earlier commencement of a prophylactic coloxyl-based laxative regimen (day 1 or 3) did not affect the rates of complications associated with constipation or diarrhea when compared to delayed introduction (day 6).