Parenteral iron therapy and phosphorus homeostasis: A review

Phosphorus has an essential role in cellular and extracellular metabolism; maintenance of normal phosphorus homeostasis is critical. Phosphorus homeostasis can be affected by diet and certain medications; some intravenous iron formulations can induce renal phosphate excretion and hypophosphatemia, likely through increasing serum concentrations of intact fibroblast growth factor 23. Case studies provide insights into two types of hypophosphatemia: acute symptomatic and chronic hypophosphatemia, while considering the role of pre‐existing conditions and comorbidities, medications, and intravenous iron. This review examines phosphorus homeostasis and hypophosphatemia, with emphasis on effects of iron deficiency and iron replacement using intravenous iron formulations.

Neostigmine decreases bupivacaine use by patient-controlled epidural analgesia during labor: a randomized controlled study

BACKGROUND

Intrathecal neostigmine not only produces analgesia but also severe nausea. In contrast, epidural neostigmine enhances opioid and local anesthetic analgesia without causing nausea. Previous studies examined only single epidural neostigmine bolus administration and did not assess the efficacy of continuous epidural infusion or several aspects of maternal and fetal safety. We therefore tested the hypothesis that epidural neostigmine in combination with bupivacaine by continuous infusion during labor would reduce the amount of bupivacaine required.

METHODS

Twelve healthy women scheduled for elective cesarean delivery were assigned to receive epidural neostigmine, 40 microg (first six subjects) or 80 microg (second six subjects) as a single bolus, with fetal heart rate (FHR) and uterine contractions monitored for 20 min. In a subsequent experiment, 40 healthy laboring women were randomized to receive bupivacaine 1.25 mg/mL alone or with neostigmine 4 microg/mL by patient-controlled epidural analgesia. The primary outcome measure was hourly bupivacaine use.

RESULTS

Epidural neostigmine bolus did not alter baseline FHR, induce contractions, or produce nausea. Epidural neostigmine infusion reduced bupivacaine requirement by 19% in all patients and 25% in those with >4 h of treatment (P < 0.05 for both) but might have contributed to the incidence of mild sedation. Mode of delivery, incidence of maternal nausea, and FHR abnormality were similar between groups.

CONCLUSIONS

These data show that adding epidural neostigmine 4 microg/mL reduces the hourly bupivacaine requirement by 19%-25% with patient-controlled epidural analgesia during labor. Administered as a bolus and by continuous infusion at the studied doses, epidural neostigmine does not cause nausea and does not induce uterine contractions or FHR abnormalities, but mild sedation can occur.

Ferric carboxymaltose injection in the treatment of postpartum iron deficiency anemia: a randomized controlled clinical trial

OBJECTIVE

The objective of the study was to evaluate the efficacy, safety, and tolerability of intravenous ferric carboxymaltose, compared with oral ferrous sulfate in women with postpartum anemia.

STUDY DESIGN

In a multicenter, randomized, controlled study, 291 women less than 10 days after delivery with hemoglobin 10 g/dL or less were randomized to receive ferric carboxymaltose (n = 143) 1000 mg or less intravenously over 15 minutes or less, repeated weekly to a calculated replacement dose (maximum 2500 mg) or ferrous sulfate (n = 148) 325 mg orally thrice daily for 6 weeks.

RESULTS

Ferric carboxymaltose-treated subjects were significantly more likely to: (1) achieve a hemoglobin greater than 12 g/dL in a shorter time period with a sustained hemoglobin greater than 12 g/dL at day 42, (2) achieve hemoglobin rise 3 g/dL or greater more quickly, and (3) attain higher serum transferrin saturation and ferritin levels. Drug-related adverse events occurred less frequently with ferric carboxymaltose.

CONCLUSION

Intravenous ferric carboxymaltose was safe and well tolerated with an efficacy superior to oral ferrous sulfate in the treatment of postpartum iron deficiency anemia.

Intravenous ferric carboxymaltose compared with oral iron in the treatment of postpartum anemia: a randomized controlled trial

OBJECTIVE

To estimate efficacy of rapid, large-dose intravenous (IV) administration of ferric carboxymaltose compared with oral iron therapy in anemic postpartum women.

METHODS

In a randomized, controlled trial, we assigned anemic women (hemoglobin [Hb] less than or equal to 10 g/dL) within 10 days postpartum to receive either IV ferric carboxymaltose (less than or equal to 1,000 mg over 15 minutes, repeated weekly to achieve a total calculated replacement dose) or ferrous sulfate (FeSO(4)) 325 mg orally thrice daily for 6 weeks.

RESULTS

One hundred seventy-four patients received 350 IV doses of ferric carboxymaltose (mean total dose 1,403.1 mg) in 3, 2, or 1 injection (10.9%, 79.3%, or 9.8% of patients, respectively); 178 received FeSO(4). Patients assigned to IV ferric carboxymaltose compared with those assigned to oral iron achieved a Hb rise greater than or equal to 2.0 g/dL earlier (7.0 compared with 14.0 days, P<.001), were more likely to achieve a Hb rise greater than or equal to 3.0 g/dL at any time (86.3% compared with 60.4%, P<.001), and were more likely to achieve a Hb greater than 12.0 g/dL (90.5% compared with 68.6%, P<.001). A similar proportion of patients achieved a Hb rise greater than or equal to 2.0 g/dL (96.4% compared with 94.1%, IV compared with oral, P=.443). There were no serious adverse drug reactions.

CONCLUSION

Large-dose IV ferric carboxymaltose administration is a new iron agent that is effective for the treatment of postpartum anemia. When compared with oral ferrous sulfate, IV ferric carboxymaltose is better tolerated, prompts a more rapid Hb response, and corrects anemia more reliably.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00396292

LEVEL OF EVIDENCE

I.

Multifactorial preoperative predictors for postcesarean section pain and analgesic requirement

BACKGROUND

The study aimed to determine predictive factors for postcesarean pain and analgesia using an assessment of pain threshold and suprathreshold thermal stimuli as well as degree of somatization and anxiety.

METHODS

Thirty-four healthy parturients scheduled for cesarean delivery under subarachnoid anesthesia were enrolled. Preoperative thermal pain threshold, intensity, and unpleasantness to heat stimuli applied to arm and lower back, State Trait Anxiety Inventory, and patient expectation for postoperative pain and need for analgesia were assessed. After surgery, overall, resting, and movement pain and analgesic consumption were recorded. Prediction of pain and analgesic use outcomes was made by principal component factor analysis, followed by stepwise linear regression.

RESULTS

Resting pain was predicted by two factors, thermal pain and unpleasantness and patient expectation (r2 = 0.26, P < 0.01), evoked pain by thermal pain threshold in the back (r2= 0.20, P < 0.009), composite pain by thermal pain and unpleasantness and preoperative blood pressure (r2 = 0.28, P < 0.008), intraoperative analgesic need by preexisting pain (r2 = 0.22, P < 0.006), recovery room analgesia by thermal pain threshold and State Trait Anxiety Inventory (r2 = 0.27, P < 0.01), and total analgesic need by State Trait Anxiety Inventory (r2 = 0.22, P < 0.01). These models predicted the upper twentieth percentile of composite pain scores and analgesic requirement with sensitivity of 0.71 to 0.80 and specificity of 0.76 to 0.80.

CONCLUSIONS

The authors' results suggest a meaningful combination of preoperative patient responses from physical and psychological tests yields a valid multifactorial predictive model for postoperative pain and analgesic requirement with significant improvements over individual predictive variables.

A randomized trial of abdominal incision suture technique and wound strength in rats

OBJECTIVE

To determine whether interrupted en bloc suture or continuous running mass suture technique for closure of abdominal incisions results in stronger wounds, and to determine the time required for each technique.

DESIGN

Randomized trial.

SETTING

Arthur C. Guyton Animal Facilities, University of Mississippi Medical Center, Jackson.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTION

A midline laparotomy was performed on 103 rats that were separated into two groups using computer-generated random numbers. In group 1, incisions were repaired using a continuous mass closure suture technique. In group 2, incisions were repaired using an en bloc interrupted suture technique.

OUTCOME MEASURES

Wound bursting pressure was determined on postoperative day 7. The time required to repair each incision was recorded.

RESULTS

Continuous mass closure suture technique resulted in significantly greater wound strength (P < .05) and required significantly less time (P < .000001).

CONCLUSION

Continuous mass closure suture technique is superior to interrupted en bloc closure with respect to wound strength and closure time.