Decreases in Mixed Venous Blood O2 Saturation in Cardiac Surgery Patients Following Extubation.

BACKGROUND: Decreases in mixed venous O2 saturation (SvO2) have been reported to occur in postcardiac surgery patients during weaning from mechanical ventilation. Our aim was to establish whether the physiological mechanism responsible for this phenomenon was a decrease in systemic O2 delivery (DO2) or an increase in global O2 consumption (V˙ O 2). METHODS: We studied 21 mechanically ventilated, postoperative cardiac patients for 30 minutes before and 60 minutes after extubation. We monitored continuously arterial O2 saturation by pulse oximetry (SaO2) and central venous O2 saturation (ScvO2) with an oximetry catheter. Mixed venous O2 saturation (SvO2) and cardiac output were also measured continuously with an oximetry pulmonary artery catheter. Systemic O2 delivery and V˙ O 2 were calculated according to accepted formulae. RESULTS: Immediately following extubation, ScvO2 and SvO2 decreased rapidly (P < .01). Systemic O2 consumption increased from 65 (57) mL·min-1 to 194 (66) mL·min-1 (P < .05) with no changes in DO2. Consequently, systemic O2 extraction rose from 38% (8%) to 45% (9%; P < .01). Preoperative left ventricular ejection fraction correlated with the decline in SvO2 postextubation. All patients weaned successfully. CONCLUSIONS: Decreases in SvO2 after discontinuation of ventilatory support in postcardiac surgery patients occur as V˙ O 2 increases in response to greater energy requirements by muscles of ventilation that are not initially matched by increases in DO2.

Reply to Brea et al. Comment on "Levitt et al. Approach to Decompensated Right Heart Failure in the Acute Setting. J. Clin. Med. 2024, 13, 869".

We would like to acknowledge and thank the authors of "Defining the Plethoric IVC" [...].

Approach to Decompensated Right Heart Failure in the Acute Setting.

Acute right heart failure (ARHF) arises when the right ventricle fails to pump blood efficiently to the pulmonary circulation. This inefficiency leads to a decreased blood supply to various organs. ARHF is a significant health concern, often leading to increased hospital admissions and being associated with a higher risk of mortality. This condition underscores the importance of effective cardiac care and timely intervention to manage its complications and improve patient outcomes. Diagnosing ARHF involves a comprehensive approach that includes a physical examination to evaluate the patient's fluid status and heart-lung function, blood tests to identify potential triggers and help forecast patient outcomes and various imaging techniques. These imaging techniques include electrocardiograms, point-of-care ultrasounds, computed tomography, cardiac magnetic resonance imaging, and other advanced monitoring methods. These diagnostic tools collectively aid in a detailed assessment of the patient's cardiac and pulmonary health, essential for effective management of ARHF. The management of ARHF focuses on addressing the underlying causes, regulating fluid balance, and enhancing cardiac function through pharmacological treatments or mechanical support aimed at boosting right heart performance. This management strategy includes the use of medications that modulate preload, afterload, and inotropy; vasopressors; anti-arrhythmic drugs; ensuring proper oxygenation and ventilation; and the utilization of heart and lung assist devices as a bridge to potential transplantation. This review article is dedicated to exploring the pathophysiology of ARHF, examining its associated morbidity and mortality, evaluating the various diagnostic tools available, and discussing the diverse treatment modalities. The article seeks to provide a comprehensive understanding of ARHF, its impact on health, and the current strategies for its management.

Diffuse large B cell lymphoma presenting as multiple cavitary lung lesions.

A female patient in her 50s presented to the hospital with a 2 months history of shortness of breath and productive cough. She also had ongoing fatigue and unintentional weight loss. Investigations demonstrated a normal white cell count and elevated lactate dehydrogenase). A CT scan of the chest revealed multiple bilateral cavitary lung masses and pulmonary nodules. Bronchoscopy with transbronchial biopsy and fine needle aspiration of mediastinal lymph node was performed. The histopathology was consistent with the non-germinal centre B cell subtype of diffuse large B cell lymphoma (DLBCL). A regimen of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone was started, which improved her symptoms. Although a rare presentation, this case highlights the need to consider DLBCL among the differential diagnoses for cavitary lung lesions when the workup fails to elicit an alternate cause. Given its aggressive nature, prompt diagnosis and treatment are critical.

Much ado about nothing.

Thirty-year-old woman with history of AIDS and anxiety presented with palpitations. Although clinically euvolemic, she was aggressively fluid resuscitated in lieu of sinus tachycardia. She developed unilateral pulmonary edema on account of left decubitus positioning and volume resuscitation. Given her normal cardiac, renal, and liver status, she spontaneously cleared the extra fluid, and the pulmonary edema resolved. This case highlights the importance of recognizing transient unilateral pulmonary edema and need for early radiographs to document clearance and prevent unnecessary testing.

Automatic detection of patient-ventilator asynchrony by spectral analysis of airway flow.

INTRODUCTION: Adequate ventilatory support of critically ill patients depends on prompt recognition of ventilator asynchrony, as asynchrony is associated with worse outcomes.We compared an automatic method of patient-ventilator asynchrony monitoring, based on airway flow frequency analysis, to the asynchrony index (AI) determined visually from airway tracings. METHODS: This was a prospective, sequential observational study of 110 mechanically ventilated adults. All eligible ventilated patients were enrolled. No clinical interventions were performed. Airway flow and pressure signals were sampled digitally for two hours. The frequency spectrum of the airway flow signal, processed to include only its expiratory phase, was calculated with the Cooley-Tukey Fast Fourier Transform method at 2.5 minute intervals. The amplitude ratio of the first harmonic peak (H1) to that of zero frequency (DC), or H1/DC, was taken as a measure of spectral organization. AI values were obtained at 30-minute intervals and compared to corresponding measures of H1/DC. RESULTS: The frequency spectrum of synchronized patients was characterized by sharply defined peaks spaced at multiples of mean respiratory rate. The spectrum of asynchronous patients was less organized, showing lower and wider H1 peaks and disappearance of higher frequency harmonics. H1/DC was inversely related to AI (n = 110; r2 = 0.57; P < 0.0001). Asynchrony, defined by AI > 10%, was associated H1/DC < 43% with 83% sensitivity and specificity. CONCLUSIONS: Spectral analysis of airway flow provides an automatic, non-invasive assessment of ventilator asynchrony at fixed short intervals. This method can be adapted to ventilator systems as a clinical monitor of asynchrony.

Contemporary Pharmacotherapeutic Approach in Pulmonary Arterial Hypertension.

Since the 1973 World Symposium on Pulmonary Hypertension, advancements in the understanding of pathophysiology and pathobiology have led to a myriad of pharmacotherapies for the disease. This article journeys through the development of therapeutic approaches for pulmonary arterial hypertension.

Impact of Novel Multiinstitutional Curriculum on Critical Care Fellow Ventilator Knowledge.

Background: Management of mechanical ventilation (MV) is a curricular milestone for trainees in pulmonary critical care medicine (PCCM) and critical care medicine (CCM) fellowships. Though recognition of ventilator waveform abnormalities that could result in patient complications is an important part of management, it is unclear how well fellows recognize these abnormalities.Objective: To study proficiency of ventilator waveform analysis among first-year fellows enrolled in a MV course compared with that of traditionally trained fellows.Methods: The study took place from July 2016 to January 2019, with 93 fellows from 10 fellowship programs completing the waveform examination. Seventy-three fellows participated in a course during their first year of fellowship, with part I occurring at the beginning of fellowship in July and part II occurring after 6 months of clinical work. These fellows were given a five-question ventilator waveform examination at multiple time points throughout the two-part course. Twenty fellows from three other fellowship programs who were in their first, second, or third year of fellowship and who did not participate in this course served as the control group. These fellows took the waveform examination a single time, at a median of 23 months into their training.Results: Before the course, scores were low but improved after 3 days of education at the beginning of the fellowship (18.0 ± 1.6 vs. 45.6 ± 3.0; P < 0.0001). Scores decreased after 6 months of clinical rotations but increased to their highest levels after part II of the course (33.7 ± 3.1 for part II pretest vs. 77.4 ± 2.4 for part II posttest; P < 0.0001). After completing part I at the beginning of fellowship, fellows participating in the course outperformed control fellows, who received a median of 23 months of traditional fellowship training at the time of testing (45.6 ± 3.0 vs. 25.3 ± 2.7; P < 0.0001). There was no difference in scores between PCCM and CCM fellows. In anonymous surveys, the fellows also rated the mechanical ventilator lectures highly.Conclusion: PCCM and CCM fellows do not recognize common waveform abnormalities at the beginning of fellowship but can be trained to do so. Traditional fellowship training may be insufficient to master ventilator waveform analysis, and a more intentional, structured course for MV may help fellowship programs meet the curricular milestones for MV.

Disappearing nodules: spontaneously regressing pulmonary amyloidosis.

A case report of spontaneous regression of pulmonary amyloidosis, diffuse interstitial pattern, in an elderly patient.

Metastatic primary pulmonary melanoma successfully treated with checkpoint inhibitors.

Our patient is a 69-year-old man who presented to the emergency department with left-sided hemiparesis that started 4 hours prior to presentation. Brain CT showed right basal ganglia and internal capsule haemorrhagic strokes. MRI revealed multiple brain lesions suspicious for metastases. Further workup revealed a 5 cm lung mass and a 1 cm pancreatic nodule. Biopsy of both pulmonary and pancreatic lesions was consistent with melanoma and was similar histologically. The patient underwent cyberknife stereotactic radiosurgery to the brain metastases followed by immunotherapy with pembrolizumab, and then by nivolumab and ipilimumab. The patient remains free of disease progression 2 years after treatment.

Predictive value of pulmonary function testing in the evaluation of pulmonary hypertension in sarcoidosis.

Background: In sarcoidosis patients, pulmonary hypertension (PH) is associated with significant morbidity and mortality. Early identification of sarcoidosis-associated pulmonary hypertension (SAPH) has substantial clinical implications. While a number of pulmonary function testing (PFT) variables have been associated with SAPH, the optimal use of PFT's in screening for SAPH is unknown. Objectives: To examine the predictive value of PFT's for echocardiographic PH in a cohort of sarcoidosis patients. Methods: We conducted a retrospective cohort study of patients with sarcoidosis from a single center over a period of five years. All consecutive adult patients with a diagnosis of biopsy-proven sarcoidosis (determined by review of the medical chart) who underwent PFT and echocardiographic testing were included. Echocardiographic risk of PH (either intermediate or high) was determined by the presence of echocardiographic PH signs and tricuspid regurgitant jet velocity. Data analysis was performed using multivariate logistic regression analysis with least absolute shrinkage and selection operator. Results: Of the 156 patients included in the study, 42 (27%) met the criteria for echocardiographic PH. Roughly equal proportions met the criteria for intermediate risk (45%) as did for high risk of PH (55%). The percent predicted of diffusion capacity for carbon monoxide (%DLCO) and forced vital capacity (%FVC) were predictive of echocardiographic PH. No other PFT variables outperformed these two markers, and the incorporation of additional PFT variables failed to significantly enhance the model. Conclusions: The %FVC and %DLCO emerged as being predictive of echocardiographic PH in this cohort of biopsy-proven sarcoidosis patients. Potentially reflecting the multifactorial pathogenesis of PH in sarcoidosis, incorporation of other PFT variables failed to enhance screening for PH in this population. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 308-316).

Combination targeted pulmonary hypertension therapy in the resolution of Dasatinib-associated pulmonary arterial hypertension.

Dasatinib is a small-molecule tyrosine kinase inhibitor used in the treatment of hematological malignancies. Pulmonary arterial hypertension (PAH) is a rare but known complication. The mainstay of treatment is cessation of Dasatinib, and while clinical improvement is rapid, complete hemodynamic resolution of pulmonary hypertension (PH) still remains exceedingly uncommon. We present a case of Dasatinib-induced PAH in a woman with chronic myeloid leukemia, who demonstrated rapid and complete clinical and hemodynamic resolution following treatment with combination pulmonary vasodilator therapy using an endothelin receptor antagonist and a phosphodiesterase-5 inhibitor. This case suggests there may be an association between the use of targeted PH medication in combination and the complete resolution of dasatinib-associated PAH, but further investigation is required.

Pleural lipoma clinically mimicking the presentation of superior sulcus tumour upon initial evaluation.

Here we present a case of a large pleural lipoma which presented with paresthesias of the hand. This is an unusual presentation of an uncommon tumour.

Upper extremity deep venous thrombosis and pulmonary embolus after ovarian hyperstimulation.

A healthy female presented with upper extremity (UE) swelling of several days duration. Admission laboratories were normal except for an elevated D-dimer. An UE ultrasound with Doppler revealed a thrombus in the right subclavian vein. A subsequent chest CT angiogram further characterised the subclavian vein thrombus and also identified a pulmonary embolus. A thorough history and laboratory evaluation showed that her only risk factors were long-time contraceptive pills and a recent cycle of ovarian hyperstimulation (OH) 7 weeks prior to presentation. Anticoagulation treatment was started and the patient's remaining outpatient work-up was negative for all other hereditary causes. A complete anatomic work-up showed bilateral thoracic outlet syndrome (TOS). A review of the literature on the occurrence of upper extremity deep venous thrombosis suggests that these usually occur in the presence of a predisposing factor, including catheters, indwelling devices and active malignancies. OH has been shown to precipitate venous thromboembolism events; however, the diagnosis of bilateral TOS as a predisposing risk factor has not been described in a patient who had recently undergone recent OH and in one who was not actively pregnant.

The role of PET scan in monitoring the progression of fibrosing mediastinitis.

We present the case of a 31-year-old man who presented with acute chest pain. Computed tomography scan showed a mediastinal mass engulfing right main-stem bronchus and another mass surrounding descending aorta. Positron emission tomography (PET) scan showed high mass metabolic activity. Histopathological evaluation revealed fibroinflammatory scarring. He was diagnosed with idiopathic fibrosing mediastinitis, started on prednisone and tamoxifen treatment, and monitored with serial PET scans. Nine months after treatment initiation, paraaortic abnormality had resolved and mediastinal mass had regressed.

Respiratory rate variability in sleeping adults without obstructive sleep apnea.

Characterizing respiratory rate variability (RRV) in humans during sleep is challenging, since it requires the analysis of respiratory signals over a period of several hours. These signals are easily distorted by movement and volitional inputs. We applied the method of spectral analysis to the nasal pressure transducer signal in 38 adults with no obstructive sleep apnea, defined by an apnea-hypopnea index <5, who underwent all-night polysomnography (PSG). Our aim was to detect and quantitate RRV during the various sleep stages, including wakefulness. The nasal pressure transducer signal was acquired at 100 Hz and consecutive frequency spectra were generated for the length of the PSG with the Fast Fourier Transform. For each spectrum, we computed the amplitude ratio of the first harmonic peak to the zero frequency peak (H1/DC), and defined as RRV as (100 - H1/DC) %. RRV was greater during wakefulness compared to any sleep stage, including rapid-eye-movement. Furthermore, RRV correlated with the depth of sleep, being lowest during N3. Patients spent most their sleep time supine, but we found no correlation between RRV and body position. There was a correlation between respiratory rate and sleep stage, being greater in wakefulness than in any sleep stage. We conclude that RRV varies according to sleep stage. Moreover, spectral analysis of nasal pressure signal appears to provide a valid measure of RRV during sleep. It remains to be seen if the method can differentiate normal from pathological sleep patterns.

The effect of race on long term mortality in mechanically ventilated patients.

OBJECTIVE: Determine the impact of race on one-year mortality following mechanical ventilation. BACKGROUND: There is a lack of prospective studies on the effect of race on survival following mechanical ventilation. METHODS: Observational study of adult patients on ventilatory support for <24 h prior to enrollment. Socioeconomic factors, laboratory and clinical data were recorded. Primary outcome was one-year mortality. RESULTS: We enrolled 178 patients; 100 African American (AA), 78 other races (OTH). One-year mortality for AA was 49% and 33% for OTH (p = 0.035). After correcting for covariates, race was not significantly associated with mortality (p = 0.42). AA patients had higher mean arterial blood pressure, serum creatinine, heart rate, and peak (p < 0.01) and mean (p = 0.05) airway pressures. CONCLUSIONS: AA patients who underwent mechanical ventilation had greater one-year mortality, although race per se was not a significant factor. It remains to be determined if strict blood pressure control and lower airway pressures may improve survival in this racial group.