Percent Of Total Blood Volume Research Articles

How low can you go? Implant density in posterior spinal fusion converted from growing constructs for early onset scoliosis.

Retrospective, multicenter comparative. Our purpose was to compare early onset scoliosis (EOS) patients treated with ultra-low, low, and high implant density constructs when undergoing conversion to definitive fusion. Larson et al. demonstrated that implant density (ID) at fusion does not correlate with outcomes in the treatment of adolescent idiopathic scoliosis, but did not address growth-friendly graduates. EOS patients treated with growth-friendly constructs converted to fusion between 2000 and 2017 were reviewed from a multicenter database. ID was defined as number of pedicle screws, hooks, and sublaminar/bands per level fused. Patients were divided into ultra-low ID (< 1.3), low (≥ 1.3 and < 1.6), and high ID (≥ 1.6). < 2years follow-up from fusion or inadequate radiographs. A total of 152 patients met inclusion criteria with 39 (26%) patients in the high ID group, 33 (22%) patients in the low ID group, and 80 (52%) in the ultra-low ID group. Groups were similar in operative time (p = 0.61), pre-fusion major curve (p = 0.71), mean number of levels fused (p = 0.58), clinical follow-up (p = 0.30), and radiographic follow-up (p = 0.90). Patients in the low ID group (11.6 ± 1.5years) were slightly younger at the time of definitive fusion than patients in the ultra-low ID group (12.9 ± 2.2years) and high ID group (12.5 ± 1.7years) (p = 0.009). There was significantly more blood loss in the high ID group than the other two groups (high ID: 946.8 ± 606.0mL vs. low ID: 733.9 ± 434.5mL and ultra-low ID: 617.4 ± 517.2mL; p = 0.01), but there was no significant difference with regard to percent of total blood volume lost (high ID: 59.3 ± 48.7% vs. low ID: 54.5 ± 37.5% vs. ultra-low ID: 51.7 ± 54.9%; p = 0.78). There was a difference in initial improvement in major curve between the groups (high ID: 21.6° vs. low ID: 18.0° vs. ultra-low ID: 12.6°; p = 0.01). However, during post-fusion follow-up, correction decreased 7.1° in the high ID group, 2.6 in the low ID group, and 2.8 in the ultra-low ID group (p = 0.19). At final follow-up, major curve correction from pre-fusion was similar between groups (high ID: 14.5° vs. low ID: 15.5° vs. ultra-low ID: 9.7°, p = 0.14). At final follow-up, there was no difference in T1-T12 length gain (p = 0.85), T1-S1 length gain (p = 0.68), coronal balance (p = 0.56), or sagittal balance (p = 0.71). The revision rate was significantly higher in the ultra-low ID group (13.8%; 11/80) versus the high ID group (2/39; 5.1%) and low ID group (0/33; 0%) (p = 0.04). Although an ID < 1.3 in growth-friendly graduates produces similar outcomes with regard to curve correction and spinal length gain as low and high ID, this study suggests that an ID < 1.3 is associated with an increased revision rate. III.

A New Low Dose of Tranexamic Acid for Decreasing the Rate of Blood Loss in Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis.

Previous studies have demonstrated that the use of tranexamic acid (TXA) reduces blood loss and transfusion requirements in children undergoing scoliosis surgery. Although TXA is safe and effective, significant adverse events have been reported. Using the lowest effective dose of TXA is advisable. We evaluated a new low dosing regimen for TXA based on an improved pharmacokinetic model and therapeutic plasma concentration. The purpose of this study is to evaluate the effectiveness of this new low dosing regimen in reducing blood loss and transfusion requirements in patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion when compared with a control group who did not receive TXA. We retrospectively reviewed 90 consecutive patients with idiopathic scoliosis undergoing posterior spinal fusion at our institution from 2017 to 2020. Forty patients received TXA at the new dosing regimen (10 mg/kg load, 5 mg/kg/h infusion) and 50 patients were in the non-TXA control group. The same 2 orthopaedic surgeons, working as a team, performed all surgical procedures. We assessed the use of TXA as an independent risk factor for estimated blood loss and transfusion requirement after adjusting for age, surgical duration, body mass index, major coronal curve, and sex. A comparison of the intraoperative cumulative blood loss in the 2 groups showed a significantly lower blood loss in the TXA group. (583.5±272.0 vs. 479.5±288.7 mL, P=0.03) This difference persisted when blood loss was calculated as percent of total blood volume and per vertebral level. Transfusion requirements were lower in the TXA group (4/50 patients vs. 0/40 patients, P=0.13). No patient in the TXA group required a blood transfusion during their hospitalization. This study is the first to provide evidence that a new low dosing regimen of TXA can significantly reduce blood loss and transfusion requirements for idiopathic scoliosis patients and supports the need for a prospective, randomized clinical trial to confirm these findings. Level III-retrospective cohort study.

The Risk of Post-Partum Hemorrhage after Cesarean Section with General versus Spinal/Epidural Anesthesia

Blood loss of over 40 percent of total blood volume (approx. 2800 ml) is typically considered a’ life danger.’ It seems rational to introduce PPH protocols at an average blood loss far below this level, as the aim of management is to prevent hemorrhage from rising to the point that it is life-threatening Objectives Caesarean anesthetic treatment, which involves general anesthesia and spinal / epidural anesthesia, was seldom examined for the risks associated with postpartum hemorrhage and was focused on only a small number of cases from single hospital data sets. The function of different types of anesthesia in postpartum hemorrhage therefore needs to be further explained. Patients and methods This are a retrospective study on patients complicated by postpartum hemorrhage after cesarean section with history of type of anesthesia used; general or spinal or epidural to improve outcome of cesarean section. We included all women complicated by postpartum hemorrhage after cesarean section and collect data about the anesthesia used during cesarean section and also recorded other risk factors for postpartum hemorrhage if recorded in files in antenatal care sheet and the intraoperative circumstances as recorded in the operative sheet of the patient. Heart rates and blood pressures of patients of both groups were measured before delivery and at 1 min interval for 15 min after injection of oxytocin. Uterine contractility was assessed for both groups at 1,2,4,6,8,10 and 15 min after oxytocin injection. Results Our results showed that the age of the studied group ranged from 18 to 40 years with mean 23.97 years. Regarding parity 44.5% of them had one child and 36.7% of them had two, 42.3% of the studied group had general anesthesia and 57.7% of them had spinal. Also 82.2% of the cases were previous and 17.8% of them were emergent. Conclusion Anesthetic techniques might be affected by the possibility of bleeding or concern. We found that women who have undergone general anesthesia have a higher risk of postpartum hemorrhage compared with women who have received epidural, spinal anesthesia

The Risk of Post-Partum Hemorrhage after Cesarean Section with General versus Spinal/Epidural Anesthesia

Blood loss of over 40 percent of total blood volume (approx. 2800 ml) is typically considered a’ life danger.’ It seems rational to introduce PPH protocols at an average blood loss far below this level, as the aim of management is to prevent hemorrhage from rising to the point that it is life-threatening Objectives Caesarean anesthetic treatment, which involves general anesthesia and spinal / epidural anesthesia, was seldom examined for the risks associated with postpartum hemorrhage and was focused on only a small number of cases from single hospital data sets. The function of different types of anesthesia in postpartum hemorrhage therefore needs to be further explained. Patients and methods This are a retrospective study on patients complicated by postpartum hemorrhage after cesarean section with history of type of anesthesia used; general or spinal or epidural to improve outcome of cesarean section. We included all women complicated by postpartum hemorrhage after cesarean section and collect data about the anesthesia used during cesarean section and also recorded other risk factors for postpartum hemorrhage if recorded in files in antenatal care sheet and the intraoperative circumstances as recorded in the operative sheet of the patient. Heart rates and blood pressures of patients of both groups were measured before delivery and at 1 min interval for 15 min after injection of oxytocin. Uterine contractility was assessed for both groups at 1,2,4,6,8,10 and 15 min after oxytocin injection. Results Our results showed that the age of the studied group ranged from 18 to 40 years with mean 23.97 years. Regarding parity 44.5% of them had one child and 36.7% of them had two, 42.3% of the studied group had general anesthesia and 57.7% of them had spinal. Also 82.2% of the cases were previous and 17.8% of them were emergent. Conclusion Anesthetic techniques might be affected by the possibility of bleeding or concern. We found that women who have undergone general anesthesia have a higher risk of postpartum hemorrhage compared with women who have received epidural, spinal anesthesia.

Tranexamic Acid Reduced the Percent of Total Blood Volume Lost During Adolescent Idiopathic Scoliosis Surgery.

Multilevel posterior spine fusion is associated with significant intraoperative blood loss. Tranexamic acid is an antifibrinolytic agent that reduces intraoperative blood loss. The goal of this study was to compare the percent of total blood volume lost during posterior spinal fusion (PSF) with or without tranexamic acid in patients with adolescent idiopathic scoliosis (AIS). Thirty-six AIS patients underwent PSF in 2011-2014; the last half (n=18) received intraoperative tranexamic acid. We retrieved relevant demographic, hematologic, intraoperative and outcomes information from medical records. The primary outcome was the percent of total blood volume lost, calculated from estimates of intraoperative blood loss (numerator) and estimated total blood volume per patient (denominator, via Nadler's equations). Unadjusted outcomes were compared using standard statistical tests. Tranexamic acid and no-tranexamic acid groups were similar (all p>0.05) in mean age (16.1 vs. 15.2 years), sex (89% vs. 83% female), body mass index (22.2 vs. 20.2 kg/m2), preoperative hemoglobin (13.9 vs. 13.9 g/dl), mean spinal levels fused (10.5 vs. 9.6), osteotomies (1.6 vs. 0.9) and operative duration (6.1 hours, both). The percent of total blood volume lost (TBVL) was significantly lower in the tranexamic acid-treated vs. no-tranexamic acid group (median 8.23% vs. 14.30%, p = 0.032); percent TBVL per level fused was significantly lower with tranexamic acid than without it (1.1% vs. 1.8%, p=0.048). Estimated blood loss (milliliters) was similar across groups. Tranexamic acid significantly reduced the percentage of total blood volume lost versus no tranexamic acid in AIS patients who underwent PSF using a standardized blood loss measure.Level of Evidence: 3. Institutional Review Board status: This medical record chart review (minimal risk) study was approved by the University of Minnesota Institutional Review Board.

Evaluation of the Safety of Posterior Cranial Vault Reconstruction

Posterior vault reconstruction involves exposure, craniotomy, and reconstruction of the occipital cranium. Although it is commonly performed, the safety and complications associated with posterior vault reconstruction have not been specifically or thoroughly examined. A retrospective chart review was performed for all patients undergoing posterior vault reconstruction at the Children's Hospital of Philadelphia between 1996 and 2006. Diagnosis, operative indication, age and weight at time of surgery, procedure type, intraoperative and postoperative complications, estimated blood loss, blood transfusion volume, and length of surgery and admission were recorded. Fifty posterior vault reconstruction cases were included in the study (17 syndromic and 33 nonsyndromic). Mean estimated blood loss was 53.6 percent (range, 15.9 to 142.9 percent) of total blood volume and was statistically greater in syndromic patients (60.6 percent versus 50.0 percent; p = 0.038). Transfusion volume averaged 66.1 percent of total blood volume but was not statistically significant. Length of surgery and number of intraoperative complications were significantly elevated in the syndromic cohort (p = 0.007 and p = 0.037, respectively), whereas length of admission and number of postoperative complications were not. Complications were intraoperative in seven patients (14 percent) and postoperative in seven (14 percent), for an overall complication rate of 28 percent. This is the largest series to date addressing the safety and complications of posterior vault reconstruction. In the authors' experience, posterior vault reconstruction carries a higher risk of intraoperative complications and blood loss compared with that reported in the literature for other types of cranial vault reconstruction. In addition, syndromic patients were more likely than nonsyndromic patients to encounter intraoperative problems.

Pathophysiologic studies of the pulmonary and coronary circulations in man

Studies of the pulmonary circulation in normal man, performed with external radiation detectors, have shown that pulmonary blood volume is about 10 percent of total blood volume. Pulmonary blood volume was unchanged in patients with acute or chronic left atria I hypertension and in normal persons during expansion of total blood volume in spite of marked increases in pulmonary vascular pressures. However, pulmonary blood volume was greatly increased in patients with polycythemia rubra vera and a large total blood volume and in patients with a left to right shunt but normal pulmonary intravascular pressure. Studies of regional myocardial perfusion with injection of xenon-133 solution into the left coronary artery revealed localized areas of ischemia distal to stenotic lesions even when the patient was at rest. During angina produced by pacing, more severe ischemia occurred, thus suggesting that functional factors reduce local perfusion below resting levels. In patients with “variant” angina, intravenous injection of thallium-201 chloride during spontaneous attacks has revealed large cold areas in myocardial scintigrams not present under control conditions, thus suggesting severe transmural reduction of perfusion in heart muscle corresponding to S-T segment elevation in the electrocardiogram.