Ventilatory Parameters Measured After One Week of Mechanical Ventilation and Survival in COVID-19-Related ARDS.

BACKGROUND: Ventilatory parameters measured soon after initiation of mechanical ventilation have limited ability to predict outcome of COVID-19-related ARDS. We hypothesized that ventilatory parameters measured after one week of mechanical ventilation might differ between survivors and non-survivors. METHODS: One hundred twenty-seven subjects with COVID-related ARDS had gas exchange and lung mechanics assessed on the day of intubation and one week later. The main parameters of interest were PaO2 /FIO2 , ventilatory ratio (VR), respiratory system compliance (CRS), and a composite score that was calculated as (PaO2 /FIO2 /100) × CRS/VR. The primary outcome was death in the ICU. RESULTS: Of the 127 subjects, 42 (33%) died in the ICU and 85 (67%) were successfully extubated. On the day of intubation, PaO2 /FIO2 , CRS, and composite score of survivors and non-survivors were similar, but survivors had a lower VR. At one week, as compared to survivors, non-survivors had a significantly higher VR (2.04 ± 0.76 vs 1.60 ± 0.43, P < .001), lower CRS (27.4 ± 6.4 mL/cm H2O vs 32.4 ± 9.3 mL/cm H2O, P = .002), and lower composite score (20.6 ± 11.9 vs 34.5 ± 18.6, P < .001), with no statistically significant difference in PaO2 /FIO2 (137 ± 49 vs 155 ± 48, P = .08). CONCLUSIONS: In subjects with COVID ARDS, parameters that reflect dead space (VR), lung mechanics (CRS), and a combined score that included PaO2 /FIO2 , VR, and CRS differed between survivors and non-survivors after one week of mechanical ventilation but with considerable overlap of values between survivors and non-survivors.

Tangential excision (saucerization) of small basal and squamous cell skin cancers with formalin horizontal (en face) comprehensive margin histopathologic evaluation.

BACKGROUND: Mohs surgery is not appropriate for all skin cancer removals. D&C has an unacceptable recurrence rate of 10-20%. A simple method of skin cancer removal is needed to fill the gap. Tangential excision is a more accurate, safer, and more time-efficient method to treat small basal cell and squamous cell skin cancers. OBJECTIVE: Detail the process of performing tangential excision of skin cancers. METHODS: A practitioner has performed this technique for 30 years. His experience is described here. RESULTS: Tangential excision (saucerization) is an excellent method used to treat small skin cancers. CONCLUSION: This technique should be considered as a better choice than D&C for the treatment of skin cancers which are not appropriate for Mohs surgery.

COVID-19 vaccines and nanomedicine.

BACKGROUND: The COVID-19 virus-induced pandemic has been the deadliest pandemic to have occurred in two generations, besides HIV/AIDS. Epidemiologists predicted that the SARS-Cov 2 pandemic would not be able to be brought under control until a majority of the world's population had been inoculated with safe and effective vaccines. A world-wide effort to expedite vaccine development was successful. Previous research for vaccines to prevent SARS and MERS, also coronaviruses, was vital to this success. Nanotechnology was essential to this vaccine development. Key elements are presented here to better understand the relationship between nanomedicine and the COVID-19 vaccine development. METHODS: NLM PubMed searches for COVID-19 vaccines, nanotechnology and nanomedicine were done. There were 6911 articles screened, 235 of which were deemed appropriate to this subject and utilized here, together with two landmark nanomedicine texts used to expand understanding of the basic science of nanotechnology. RESULTS: SARS-Cov 2, caused by the COVID-19 virus, was first recognized in China in December of 2019 and was declared as a pandemic in March of 2020. The RNA sequence was identified in January of 2020. Within 4 months of the viral genome being released, over 259 vaccines had been in development. The World Health Organization (WHO) anticipated a vaccine with a 50-80% efficacy to be developed within 1-2 years. Ahead of schedule, the Food and Drug Administration (FDA) announced the emergency authorization approval for two mRNA vaccines within 11 month's time. Nanotechnology was the key to the success of these rapidly developed, safe and effective vaccines. A brief review of pertinent basic science principles of nanomedicine are presented. The development of COVID vaccines is reviewed. Future considerations are discussed. CONCLUSIONS: Control of the COVID-19 SARS-Cov2 pandemic benefitted from nanomedicine principles used to develop highly effective, yet very safe and relatively inexpensive vaccines. These nanovaccines can be much more easily altered to adjust for viral variants than traditional live or inactivated legacy-type whole virus vaccines.

Lack of Benefit of Heliox During Mechanical Ventilation of Subjects With Severe Air-Flow Obstruction.

BACKGROUND: The value of heliox (helium-oxygen mixture) for patients with severe air-flow obstruction is uncertain. The purpose of this study was to determine whether heliox could reduce the degree of hyperinflation and hypercapnia in mechanically ventilated patients with severe air-flow obstruction. METHODS: This was a single-center, prospective observational study conducted in a medical ICU of an academic medical center. We assessed the impact of heliox (65-70% helium, 30-35% oxygen) on airway pressures and arterial blood gases of 13 subjects undergoing mechanical ventilation for severe asthma (n = 8) or exacerbation of COPD (n = 5). RESULTS: As compared with ventilation with air-O2, heliox resulted in a reduction in peak airway pressure (54.1 ± 12.6 cm H2O vs 47.9 ± 10.8 cm H2O, P < .001) and PaCO2 (64.3 ± 14.9 mm Hg vs 62.3 + 15.1 mm Hg, P = .01). In contrast, there was no change in plateau pressure (25.3 ± 5.5 cm H2O vs 25.8 ± 5.6 cm H2O, P = .14) or total PEEP (13.4 ± 3.8 cm H2O vs 13.3 ± 4.1 cm H2O, P = .79) in response to heliox. CONCLUSIONS: In mechanically ventilated subjects with severe air-flow obstruction, administration of heliox had no effect on indices of dynamic hyperinflation (plateau pressure and total PEEP) and resulted in only a small reduction in PaCO2 .

The effect of caffeine on hearing in a guinea pig model of acoustic trauma.

OBJECTIVE: Caffeine is a widely consumed substance affecting the metabolism of adenosine and cellular metabolism of calcium. Noise also affects these metabolic pathways while inducing hearing loss. The aim of this study was to determine the effect of daily intake of caffeine on hearing loss after an episode of acoustic trauma in guinea pigs. MATERIALS AND METHODS: In this pilot study, forty guinea pigs were randomly divided into four groups: group I (control, n=10) received intraperitoneal saline, group II (n=10) received intraperitoneal caffeine (120 mg/kg/day) for 14 days, group III (n=10) was exposed to noise (tone of 6 kHz at 120 dB for one hour) and group IV (n=10) was exposed to noise as group III and received caffeine as group II. Auditory brainstem responses were measured at four different frequencies (8, 16, 20, and 25 kHz) prior to and at intervals of 1h, 3 days, 10 days, and 14 days after the initial treatment. On day 14, morphological analysis was performed to assess the effects of caffeine on acoustic trauma. RESULTS: Aggravated hearing loss was observed in group IV after 10 days of follow-up. After 14 days, one of the four frequencies (8 kHz) tested showed statistically significant greater impairment in hearing (8.2 ± 3.6 dB, p=0.026). Auditory hair cells showed no difference while spiral ganglion cell counts were diminished in group IV (p<0.05). CONCLUSION: These findings indicate that caffeine may have a detrimental effect on hearing recovery after a single event of acoustic trauma.

Use of expiratory change in bladder pressure to assess expiratory muscle activity in patients with large respiratory excursions in central venous pressure.

BACKGROUND: Expiratory muscle activity may cause the end-expiratory central venous pressure (CVP) to greatly overestimate right atrial transmural pressure. METHODS: We recorded CVP and expiratory change in intra-abdominal pressure (ΔIAP) in 39 patients who had a respiratory excursion in CVP from end-expiration to end-inspiration (CVP(ee)-CVP(ei)) ≥ 8 mmHg. Uncorrected CVP was measured at end-expiration, and corrected CVP was calculated as uncorrected CVP-ΔIAP. In 13 patients measurements were repeated during relaxed breathing. RESULTS: The CVP(ee)-CVP(ei) was 15.2 ± 6.3 mmHg (range 8-34 mmHg), and ΔIAP was 7.4 ± 6.0 mmHg (range 0-30 mmHg). Uncorrected CVP was 18.3 ± 6.1 mmHg, and corrected CVP was 10.9 ± 3.9 mmHg. There was a significant positive correlation between CVP(ee)-CVP(ei) and ΔIAP (r = 0.814). However, some patients with a large CVP(ee)-CVP(ei) had negligible ΔIAP. In a subset of 13 patients with active expiration who had a relaxed CVP tracing available for comparison, the difference between uncorrected CVP and relaxed CVP was much greater than the difference between corrected CVP and relaxed CVP (7.3 ± 3.0 vs. 1.1 ± 0.7 mmHg, p < 0.001). CONCLUSION: Patients with large respiratory excursions in CVP often have significant expiratory muscle activity that will cause their CVP to overestimate transmural right atrial pressure. The magnitude of expiratory muscle activity can be assessed by measuring ΔIAP. Subtracting ΔIAP from the end-expiratory CVP usually provides a reasonable estimate of the CVP that would be obtained if exhalation were passive.

Use of bladder pressure to correct for the effect of expiratory muscle activity on central venous pressure.

OBJECTIVE: To assess whether subtracting the expiratory change in intra-abdominal (bladder) pressure (Delta IAP) from central venous pressure (CVP) provides a reliable estimate of transmural CVP in spontaneously breathing patients with expiratory muscle activity. DESIGN AND SETTING: Prospective observational study in a medical ICU. PATIENTS: Twenty-four spontaneously breathing patients with central venous and bladder catheters: 18 with no clinical evidence of active expiration (group 1) and 6 with active expiration (group 2). INTERVENTIONS: Patients in group 1 were coached to change their breathing pattern to one of active expiration for several breaths; those in group 2 were asked to sip water through a straw to briefly interrupt active expiration. MEASUREMENTS AND RESULTS: During active expiration end-expiratory CVP (uncorrected CVP) and Delta IAP were measured; Delta IAP was subtracted from uncorrected CVP to obtain corrected CVP. End-expiratory CVP during relaxed breathing (best CVP) was assumed to represent the best estimate of transmural CVP. The absolute difference between corrected CVP and best CVP was much less than the difference between uncorrected CVP and best CVP (2.3+/-2.0 vs. 12.5+/-4.7 mmHg). CONCLUSIONS: In patients with active expiration, subtracting Delta IAP from end-expiratory CVP yields a more reliable (and lower) estimate of transmural CVP than does the uncorrected CVP value.

Hepatic imaging in the 21st century.

Imaging of the liver has progressed rapidly during the past decade with continued advancement of current ultrasound, computed tomography, and magnetic resonance imaging (MRI). Each modality not only has seen refinement enabling better anatomic characterization of disease but also has received strength from the addition of new techniques to its resources. New contrast agents have become available for all modalities and some agents, particularly for MRI, have opened the way for better functional assessment. MRI continues to see an elaboration of sequences (including spectroscopy and diffusion) that also open imaging to the microscopic structure of disease and normal function. The further development of workstations have improved both analysis and depiction of disease. In the 21st century imaging will continue to shift from a simple source of anatomic information to a more functional problem-solving tool.

Diagnostic value of tissue harmonic imaging compared with conventional sonography.

The purpose of this study was to determine if tissue harmonic imaging (THI) produced diagnostic images more frequently than conventional sonography. A prospective study was performed on 33 patients, to compare the diagnostic value of THI with conventional sonography. Each examination was performed using THI (transmit frequency=2.0 MHz, receive frequency=4.0 MHz) and conventional sonography at 2.5 and 4.0 MHz. The different sonographic techniques were then graded as to whether they produced diagnostic images. THI produced diagnostic images in 33 of 33 examinations (100%), 2.5 MHz conventional sonography produced diagnostic images in 26 of 33 examinations (79%), and 4.0 MHz conventional sonography produced diagnostic images in 26 of 33 examinations (79%). THI produced diagnostic images significantly more frequently than 2.5 MHz conventional sonography (p=.0233) and 4.0 MHz conventional sonography (p=.0233). The THI technique produced diagnostic images more frequently than conventional sonography.

Effect of prolongation of expiratory time on dynamic hyperinflation in mechanically ventilated patients with severe asthma.

OBJECTIVE: To assess the effect of a decrease in respiratory rate on dynamic hyperinflation, as determined by changes in plateau airway pressure, in patients with status asthmaticus whose baseline minute ventilation approximated 10 L/min. DESIGN: Observational descriptive study. SETTING: Medical intensive care unit. PATIENTS: Twelve patients with severe asthma mechanically ventilated in the assist control mode with a tidal volume of 613 +/- 100 mL and an inspiratory flow rate of 79 +/- 4 L/min. INTERVENTIONS: A decrease in respiratory rate from 18 to 12 and 6 breaths/min. MEASUREMENTS AND MAIN RESULTS: Plateau airway pressure decreased by approximately 2 cm H2O (25.4 +/- 2.8 vs. 23.3 +/- 2.6 cm H2O, p <.01) when respiratory rate was decreased from 18 to 12 breaths/min (increase in expiratory time 1.7 secs) and by a similar amount (23.3 +/- 2.6 vs. 21.3 +/- 2.9 cm H2O, p <.01) when respiratory rate was decreased from 12 to 6 breaths/min (increase in expiratory time 5 secs). Peak airway pressure was similar at the three respiratory rates (66.8 +/- 8.7 vs. 66.4 +/- 9.5 vs. 67.8 +/- 11.1 cm H2O at 18, 12, and 6 breaths/min, respectively). End-expiratory flow rates (n = 7) were 61.4 +/- 12.6, 38.6 +/- 4.5, and 23.1 +/- 5.8 mL/sec at respiratory rates of 18, 12, and 6 breaths/min, respectively. CONCLUSIONS: Prolongation of expiratory time decreases dynamic hyperinflation in patients with status asthmaticus, as evidenced by a reduction in plateau airway pressure, but the magnitude of this effect is relatively modest when baseline minute ventilation is < or = 10 L/min, because of the low end-expiratory flow rates. Since flow progressively decreases throughout expiration, the reduction in dynamic hyperinflation resulting from a given prolongation of expiratory time will depend on the baseline respiratory rate (i.e., less reduction in dynamic hyperinflation at a lower respiratory rate). Changes in peak airway pressure may not always reflect the changes in dynamic hyperinflation that result from prolongation of expiratory time.

Panoramic ultrasound of the thyroid.

Panoramic ultrasound is a technical modification of conventional ultrasound that produces images with a large anatomic field of view. Images obtained with this technique display both lobes of the thyroid gland on a single image, and provide an accurate imaging representation of a variety of thyroid disorders. This report describes the use of panoramic ultrasound and presents examples of panoramic ultrasound of the thyroid.

Overestimation of pulmonary artery occlusion pressure in pulmonary hypertension due to partial occlusion.

OBJECTIVE: To evaluate partial occlusion in patients with pulmonary hypertension with regard to a) the degree to which it leads to overestimation of pulmonary artery occlusion pressure (Ppao) and b) identification of factors that could enhance its recognition. DESIGN: Observational descriptive study. SETTING: Medical intensive care unit. PATIENTS: Fourteen patients with pulmonary hypertension and an increased pulmonary artery diastolic pressure (Ppad) - Ppao gradient (> or = 10 mm Hg). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The Ppao was recorded during partial occlusion (partial Ppao) and after catheter repositioning to obtain a lower, more accurate value (best Ppao). The error due to partial occlusion, defined as the difference between the partial Ppao and the best Ppao, was 13 +/- 5 mm Hg (range, 6-21 mm Hg). The previously widened Ppad - Ppao gradient invariably narrowed during partial occlusion and then increased by 13 +/- 5 mm Hg (range, 5-23) during the best Ppao measurement. There was a moderate correlation between the error due to partial occlusion (partial Ppao - best Ppao) and both the mean pulmonary artery pressure (r =.77, <.01) and the Ppad - Ppao gradient (r =.79, <.01). CONCLUSIONS: Partial occlusion in patients with pulmonary hypertension may lead to significant overestimation of the Ppao and should be suspected when there is a substantial increase in the Ppao without a concomitant increase in the Ppad, as reflected by a marked narrowing of a previously widened Ppad - Ppao gradient.

A pilot project to study the use of ultrasonography for teaching physical examination to medical students.

The purpose of this study was to study the use of ultrasound as an aid to teaching physical examination. Five medical students were given a 1-week course in ultrasound, and were then assigned to clinical rotations to perform ultrasound and physical examinations on patients. Basic ultrasound skills were assessed by having each student scan the same normal model at the conclusion of the first week and at the conclusion of the project. Clinical cases were presented to a preceptor, and the ultrasound images were graded on a five-point scale. At the end of the first week, the mean grade of ultrasound examinations performed on the control model was 3.2, improving to 4.4 at the end of the project. Grading of ultrasound exams performed during the first clinical week averaged 4.1, improving to 4.5 at the end of the project. An exit survey indicated a favorable response to using ultrasound as an educational tool.

Double Orifice Mitral and Tricuspid Valves.

Atrioventricular valve duplication is a rare congenital cardiac anomaly. The anomaly is usually recognized as an incidental finding at autopsy, open heart surgery, or two-dimensional echocardiography. In this article we present the transthoracic and transesophageal presentation of a case of mitral and a case of tricuspid valve duplication. The hemodynamic consideration of the lesions is discussed with a review of the literature. (ECHOCARDIOGRAPHY, Volume 13, January 1996)