Proceedings of the Food and Drug Administration's public workshop on new red blood cell product regulatory science 2016

The US Food and Drug Administration (FDA) held a workshop on red blood cell (RBC) product regulatory science on October 6 and 7, 2016, at the Natcher Conference Center on the National Institutes of Health (NIH) Campus in Bethesda, Maryland. The workshop was supported by the National Heart, Lung, and Blood Institute, NIH; the Department of Defense; the Office of the Assistant Secretary for Health, Department of Health and Human Services; and the Center for Biologics Evaluation and Research, FDA. The workshop reviewed the status and scientific basis of the current regulatory framework and the available scientific tools to expand it to evaluate innovative and future RBC transfusion products. A full record of the proceedings is available on the FDA website (http://www.fda.gov/BiologicsBloodVaccines/NewsEvents/WorkshopsMeetingsConferences/ucm507890.htm). The contents of the summary are the authors' opinions and do not represent agency policy.

Bone segmentation applying rigid bone position and triple shadow check method based on RF data

Noninvasive 3D reconstruction of a bone requires very accurate 2D navigated scans of bone. The use of brightness-mode ultrasound seems to be promising, if some 2D scans of bone are obtained in a fully automatic manner. This paper presents a rapid and fully automatic method for segmenting bone in a standard 2D ultrasound image (B-mode image). The algorithm focuses on segmenting bone in the B-mode image using RF data of the image. The article introduces the signal-processing scheme designed based on RF data to automatically segment bone in the B-mode image. The segmentation accuracy was assessed by performing various tests for this algorithm for various locations of the limbs of the human body. The algorithm was tested for 120 images taken at different locations of limbs of the human body. The sensitivity of these tests was calculated to be 0.99 and specificity was found to be 1. The suggested segmentation approach provides a reliable means of detecting bone in B-mode image.

High-frequency oscillatory ventilation of the perfluorocarbon-filled lung: Dose-response relationships in an animal model of acute lung injury

OBJECTIVE

To examine dose-response relationships regarding the efficiency of gas exchange and hemodynamic function during high-frequency oscillation and partial liquid ventilation (HFO-PLV) of the perfluorocarbon (PFC)-treated lung in a model of acute lung injury.

SETTING

An animal research laboratory in a university medical center.

DESIGN

A prospective, randomized study comparing animals receiving varying doses (0, 5, 15, and 20 mL/kg) of perflubron during high-frequency oscillatory ventilation (HFOV) with mean airway pressure (Paw) optimized to achieve a minimal percutaneous oxygen saturation (Spo2).

SUBJECTS

Nineteen healthy swine (mean weight 28.9 kg) with saline lavage-induced acute lung injury.

METHODS

Animals were treated with repetitive saline lavage to achieve a uniform degree of acute lung injury (Spo2 < or =90% on an Fio2 of 1.0). After lung injury, subjects were converted to HFOV, and lung volume was optimized. HFO-PLV was initiated by instillation of perflubron at a rate of 0.5 mL.kg-1.min-1 to achieve total doses of 5, 15, and 20 mL/kg. After PFC dosing, the only experimental manipulation consisted of adjustment of Paw to achieve an Spo2 of 90% +/- 2% with Fio2 of 0.6. Gas exchange, hemodynamic variables, and pulmonary mechanics data were collected over a 1-hr period. Five control animals were not dosed with perflubron and remained on HFOV for the 1-hr period of data collection.

MEASUREMENTS AND MAIN RESULTS

After lung volume recruitment with HFOV, the initiation of HFO-PLV was best tolerated with the two lower doses in our protocol. There were essentially no changes in Paco2 or pH between groups over the dosing interval. After dosing, analysis of variance demonstrated a PFC dose-dependent effect for oxygenation index (p =.01) only; the lowest oxygenation index was found in the 15 mL/kg group (p =.01). In the 15 mL/kg group, the Paw decreased steadily from 20.6 +/- 3.4 cm H2O at the end of dosing to 18.0 +/- 4.9 cm H2O at 60 mins. The Pao2 increased from 113 +/- 51 torr (15.06 +/- 6.79 kPa) to 134 +/- 49 torr (17.86 +/- 6.53 kPa) during this period and was associated with a decreasing oxygenation index (from 11.4 +/- 2.0 to 9.3 +/- 1.5). The cardiac index and pulmonary vascular resistance did not change significantly during the dosing period and were relatively stable after the completion of dosing.

CONCLUSIONS

The combination of HFOV and perflubron administration was well tolerated hemodynamically and was not associated with deterioration of gas exchange during dosing. Our data suggest that the optimal dose of perflubron to achieve the lowest oxygenation index during HFO-PLV is between 5 and 15 mL/kg. The combination of HFOV and perflubron administration is a novel strategy in the treatment of acute lung injury that shows some promise and merits additional investigation. We hope in future studies to address the histopathologic effects of varying perflubron doses during HFOV in a long-term study of the lung-protective effects of HFO-PLV.

Optimizing intrapulmonary perfluorocarbon distribution: Fluoroscopic comparison of mode of ventilation and body position

OBJECTIVE

Partial liquid ventilation with the perfluorochemical, perflubron, has been shown to improve lung mechanics and enhance gas exchange in the treatment of severe acute lung injury. However, the most effective strategy to provide optimal intrapulmonary distribution of perflubron has not been fully accessed. The objective of this study was to examine the effect of body position (supine vs. rotational) and mode of ventilation (conventional mechanical ventilation [CMV] vs. high-frequency oscillatory ventilation [HFOV]) on perflubron distribution and oxygenation improvement.

DESIGN

Prospective, randomized, animal trial.

SETTING

Research laboratory at a university medical center.

SUBJECTS

Twenty healthy piglets (4.5-6.6 kg).

INTERVENTIONS

Subjects underwent repetitive saline lavage to achieve a uniform degree of lung injury and then were randomized to either CMV or were converted to HFOV. Within each ventilator group, animals were randomized to supine positioning (S) or rotational positioning with alternation between supine and prone position (R) during incremental dosing of three 5-mL/kg doses of perflubron.

MEASUREMENTS AND MAIN RESULTS

Arterial blood gas tensions, hemodynamic variables, and the oxygenation index were recorded after each dose of 5 mL/kg. Lateral cinefluoroscopic images after each dose were digitized for computer analysis of density. A density index was calculated for a 2-cm2 window in three dorsal and three ventral lung regions. Uniformity of distribution was calculated by comparing the mean density among the six regions. Oxygenation improvements were compared between groups. There were no significant differences in hemodynamic variables or gas exchange after lung injury in the four groups. Rotational positioning produced significantly more uniform perflubron distribution during both CMV and HFOV. This effect was independent of the mode of ventilation. The mean ventral density index was affected by rotating position and HFOV mode of ventilation after 10 mL/kg of perflubron, and rotating position was affected only after 15 mL/kg of perflubron. There was a significant reduction in the oxygenation index from baseline to end lavage in both CMV groups, as well as all of the animals that were rotated.

CONCLUSION

Perflubron is more uniformly dispersed when dosed in a rotational fashion with alternation between supine and prone position during incremental dosing. This effect is independent of mode of ventilation. There was no relationship between oxygenation improvements and nondependent perflubron distribution. CMV and rotating dosing both led to a significant decrease in the oxygenation index after a 15 mL/kg dose of perflubron. This information has important impact on the future development of dosing strategies and clinical trial design.

High-frequency oscillatory ventilation of the perfluorocarbon-filled lung: preliminary results in an animal model of acute lung injury

OBJECTIVE

To examine the efficiency of gas exchange, hemodynamic function, and histopathologic evidence of lung protection using high-frequency oscillation of the perfluorocarbon-filled lung in a model of acute lung injury.

SETTING

An animal research laboratory.

DESIGN

A prospective, randomized animal study comparing animals randomized to high-frequency oscillation or high-frequency oscillation and perfluorocarbon administration (perfluoro-octyl bromide, perfubron, or LiquiVent).

SUBJECTS

Ten healthy swine (mean weight, 24.6 kg) with saline lavage-induced acute lung injury.

INTERVENTIONS

Animals were treated with repetitive saline lavage to achieve a uniform degree of acute lung injury (Pao2 of <90 torr [11.9 kPa] on a Fio2 of 1.0). After lung injury, subjects were changed to high-frequency oscillatory ventilation and stabilized for 1 hr. High-frequency oscillation of the perfiuorocarbon-filled lung was initiated in five animals with the instillation of 30 mUkg perflubron and five animals continued receiving high-frequency oscillation for a total duration of 2 hrs after the dosing period. Histopathologic evidence of lung injury was quantified by a pathologist using an eight-variable lung injury scoring system to generate a lung injury score.

MEASUREMENTS AND MAIN RESULTS

Administration of perflubron did not produce acute alterations of gas exchange. After the dosing period, there were no differences in gas exchange, hemodynamic function, or pulmonary vascular resistance between the two groups. The perfluorocarbon-treated animals had a significantly lower histopathologic total lung injury score, primarily manifested by significantly less atelectasis.

CONCLUSIONS

The combination of high-frequency oscillatory ventilation and partial liquid ventilation with perfiubron was well tolerated hemodynamically, was not associated with deterioration of gas exchange during dosing, and did not produce significant differences in either gas exchange or hemodynamic variables over a 2-hr period. There was histopathologic evidence that the combination of high-frequency oscillation and perfiubron administration produces improved recruitment in both dependent and nondependent lung regions.

Pulmonary blood flow distribution during partial liquid ventilation

Regional pulmonary blood flow was investigated with radiolabeled microspheres in four supine lambs during the transition from conventional mechanical ventilation (CMV) to partial liquid ventilation (PLV) and with incremental dosing of perfluorocarbon liquid to a cumulative dose of 30 ml/kg. Four lambs supported with CMV served as controls. Formalin-fixed, air-dried lungs were sectioned according to a grid; activity was quantitated with a multichannel scintillation counter, corrected for weight, and normalized to mean flow. During CMV, flow in apical and hilar regions favored dependent lung (P < 0.001), with no gradient across transverse planes from apex to diaphragm. During PLV the gradient within transverse planes found during CMV reversed, most notably in the hilar region, favoring nondependent lung (P = 0.03). Also during PLV, flow was profoundly reduced near the diaphragm (P < 0.001), and across transverse planes from apex to diaphragm a dose-augmented flow gradient developed favoring apical lung (P < 0.01). We conclude that regional flow patterns during PLV partially reverse those noted during CMV and vary dramatically within the lung from apex to diaphragm.

Group A beta-hemolytic streptococcal bacteremia: historical overview, changing incidence, and recent association with varicella

OBJECTIVE

To quantitate the increase in invasive group A beta-hemolytic streptococcal (GABHS) infections and to define a possible association between GABHS bacteremia and primary varicella zoster virus (VZV) infections.

METHODS

This was a retrospective chart review conducted at Children's Hospital. Participants were patients with documented GABHS bacteremia occurring from January 1977 through December 1993.

MEASUREMENTS/MAIN RESULTS

We identified 63 episodes of GABHS bacteremia in 62 patients. From 1977 to 1992, a mean of 3.2 +/- 2 cases occurred per year (range, 0 to 6), increasing by a factor of 3 (10 cases) in 1993. The median age was 4 years (range, 1 day to 20 years; mean, 8 years +/- 3 months); 36 were male; five children were immunocompromised. One child was dead on arrival and one had a cardiac arrest during evaluation in the emergency department. Primary sites of infection (oropharynx, skin, or middle ear) were identified in 40 (75%) of the cases; in addition, 10 cases occurred in patients with primary VZV. From 1977 to 1992, we identified five VZV-associated cases; an average of 7 +/- 11.5% of the patients with GABHS had concurrent VZV infection annually, with no more than one case per year. In 1993, 50% of the 10 new GABHS cases were in children with VZV infection (P = .003, Fisher's exact test). The diagnosis of invasive GABHS infection in patients with VZV was not readily recognized, requiring a median of two (range, one to four) physician visits before admission and the administration of antibiotics. All 10 children were diagnosed on the fourth or fifth day of the exanthem and were febrile (39.6 +/- 1.1 degrees C, range, 38.3 to 40.8 degrees C), with a mean white blood cell count (WBC) of 11,500 +/- 8,400/mm3 (8 of 10 cases had a WBC less than 15,000/mm3). None of the five VZV-associated cases in 1993 had signs of cutaneous bacterial superinfection; among these were two cases of streptococcal toxic shock syndrome (one death), one case of osteomyelitis, and two cases of occult bacteremia. Of the five VZV-associated cases before 1993, one patient was diagnosed with supraglottitis, one with septic arthritis, one with orbital cellulitis, and two solely with impetiginized or cellulitic lesions.

CONCLUSIONS

We found that the incidence of invasive GABHS infections has risen dramatically, increasing by a factor of 3 over the past year. In 1993, 50% of new cases of invasive GABHS disease were associated with VZV infection. Invasive GABHS should be considered in children with VZV who manifest fever on or beyond the fourth day of the exanthem. The absence of an elevated WBC and impetiginized or cellulitic lesions should not eliminate this diagnosis from consideration.

A methodology to evaluate motion of the unstable spine during intubation techniques

Airway management in patients with an unstable cervical spine remains a challenge. A video fluoroscopic technique that transfers the image to a floppy disk for direct measurement is described. This technique enabled standardized, direct measurement of the cervical spine during airway maneuvers before and after a C5-6 posterior instability was surgically created in five cadaveric specimens. Unsupported direct oral techniques often can cause more motion than do indirect nasal techniques, and chin lift/jaw thrust and cricoid pressure can cause as much motion as do some of the intubation techniques.

A new compound curved needle for intradermal suture closure

A new compound curved needle has been designed and developed for intradermal suture closure from a unique stainless steel alloy, American Society of Testing Materials (ASTM) 45500. This needle has a short, straight, sharpened point with a reverse cutting edge, followed by a curved distal section. Despite its geometry, it exhibited a similar resistance to bending and breakage as did a curved needle with a single radius of curvature manufactured from the same alloy. The design of this new needle enabled the physician to pass it through the dermis with a greater accuracy to a controlled depth and length of bite than curved cutting edge needle with a single radius of curvature.

Emergency medicine magnifying loupes

A magnifying loupe system has been evaluated for use in emergency medicine. Physicians uniformly preferred a Keplerian lens system over that of the Galilean lens system. The advantages of the Keplerian lens were its increased field of view and its brighter and clearer peripheral image. The Keplerian loupes allowed the physician to visualize the exquisite details of wound configuration and to perform wound closure using microsurgical techniques.

Multiple sclerosis and brain tumor: a diagnostic challenge

Multiple sclerosis may present as a lesion indistinguishable clinically and radiologically from brain tumor. A case of multiple sclerosis is reported with clinical and radiologic features of a brain tumor. A brain biopsy was later undertaken that provided pathological confirmation of the diagnosis of this demyelinating disease. This case report in conjunction with those in the literature indicate that conservative treatment with steroid therapy and serial computed tomography should establish the diagnosis of multiple sclerosis without the need for surgical intervention.

Evaluation of cohesive and elastic support bandages for joint immobilization

The purpose of this clinical study was to compare the performance of a new cohesive bandage to that of elastic bandages for joint immobilization. The magnitude of joint immobilization by these bandages was quantitated during isokinetic exercise using a computerized dynamometer. The degree to which the cohesive and elastic bandages reduced range of motion and peak torque of plantar and dorsiflexion was not significantly different. After exercising for 1 hour, the elastic bandage loosens, reducing its ability to immobilize the joint. In contrast, the cohesive bandage maintains its configuration, despite active exercise for 1 hour.

Evaluation of automatic disposable rotating cartridge skin staplers

Burn surgeons commonly employ skin staples for the application of skin grafts and to secure dressings on donor site dressings and over skin grafts. Disposable skin staplers with rotating cartridges are ideally suited for wound closure because the position of their cartridges can be manually adjusted to facilitate placement of their staples. In response to the burgeoning interest in disposable automatic skin staplers with rotating cartridges, three different models are now commercially available. This report describes the design configuration and mechanical performance of these disposable automatic staplers and their staples. Mechanical performance of these staplers and staples has been assessed by standardized tests that can be replicated in any research laboratory. On the basis of these objective design and performance parameters, the Premium stapler is recommended for wound closure. This stapler provides maximal visualization of the wound as well as the staple during its formation. It delivers the staple into the skin or wound in a manner that the cross member of the staple is above the skin or wound surface. In addition, the Premium stapler has a prepositioning mechanism that can be controlled by the surgeon with minimal force. This mechanism allows the stapler to hold its staple securely, even when its pointed legs extend beyond the delivery end of the stapler. Force required to form its staples is so low that the surgeon can staple repetitively without fatigue. Finally, the Premium stapler delivers a staple that has a uniform geometry and sharp points that can easily penetrate tissue.

Histology and ultrastructure of the carotid sinus in experimental hypertension

Histological studies including electron microscopy were performed on the carotid sinuses of dogs with renal hypertension of 17 to 82 days duration or hypertension of two years secondary to aortic coarctation. Physiological abnormalities in the baroreceptors including resetting had been demonstrated before death. Histologically there were no qualitative or quantitative differences in the intrasinus nerve fibers of the hypertensive animals compared tp controls with normal blood pressures, and there was no evidence that baroreceptor degeneration occurred as a consequence of the hypertension. Structural lesions confined to the intima were evident in the sinus walls of some of the renal hypertensive animals whereas the dogs with coarctation showed more advanced sinus wall changes including medial calcification and enlargement of the vascular lumen.

Cephalothin Prophylaxis and valve replacement

In a study of antibiotic prophylaxis in adults undergoing heart valve replacement, we found that a 2 gm dose of cephalothin given intraoperatively produced adequate antimicrobial activity in the bloodstream throughout the period of cardiopulmonary bypass. A dosage of 1 gm every four hours postoperatively did not lead to significant accumulation of the antibiotic. With prophylaxis restricted to the intraoperative and early postoperative period, adverse drug reactions and superinfections were not a problem. Further, no cases of prosthetic valvulitis were encountered.

Baroreflex sensitivity and carotid sinus dimensions in dogs with coarctation

Baroreflex sensitivity (BRS) has not been assessed in coarctation, though it is diminished in renal and essential hypertension. Previous experimental studies of coarctation have dealt primarily with renal mechanisms of hypertension, and have relied on constricting the aorta in adult animals. We banded the thoracic aorta in newborn puppies, and performed studies 2 yr later. Blood pressure (BP) elevations, abundant chest wall collaterals, the absence of heart failure, and subsequent necropsy confirmed the full syndrome of natural coarctation in all dogs. Transient BP elevations were induced in conscious, unrestrained dogs with intravenous phenylephrine injections. Reflex bradycardia was quantitated by plotting each pulse interval in microseconds against BP of the preceding beat, and expressing BRS as the linear regression coefficient (slope) in ms/mmHg. Mean BRS in 10 dogs with coarctation did not differ significantly (P greater than 0.1) from 8 normal controls. Carotid sinus diameter (CSD) was also assessed. Carotid arteries were fixed in vivo by prolonged exposure to glutaraldehyde to prevent contraction, then were excised and measured in a calibrated microscope. Mean CSD in 10 dogs with coarctation was significantly greater (P less than 0.01) than in 10 control dogs. The unexpectedly normal BRS in experimental coarctation may be due to changes in CSD induced by hypertension; such changes may only develop in growing animals. Experimental studies of coarctation should use a preparation that mimics the natural lesion.

Surgical repair of acute ventricular spetal defect complicating myocardical infarction

Ventricular septal defect complicating myocardial infarction was repaired surgically in seven patients between 1965 and 1974. In four, the septal defect had developed in the lower portion of the septum and in three, high in the septum, above the origin of the papillary muscle. Concomitant operations included mitral valve replacement and infarctectomy, in one patient, and triple aortocoronary bypass in another. The commoner low defect was repaired either by amputating the lower portion of the heart or patch-repairing through a left ventriculotomy incision. The higher defects, more difficult to repair, were repaired through a high posterior left ventriculotomy. Complete pre- and postoperative hemodynamic studies were carried out and follow-up information was available for all patients. Recognition of the high defect is essential. Pathologically, the coronary artery lesion is more complicated and extensive and a different surgical approach is necessary. A classification of high and low ventricular septal defects developing after myocardial infarction is recommeneded. The natural history of the disease and the reasonable surgical results support an active surgical approach in both types of postinfarction septal perforation.

Villous papilloma of the appendix associated with mucocoele and intussusception

A case of villous papilloma of the appendix, associated with mucocoele formation and intussusception, is described. The literature is reviewed and it appears that there is no previous report of this association. It is suggested that so-called malignant mucocoeles of the appendix arise from pre-existing villous papillomas.