A four-dimensional dynamic conformal arc approach for real-time tumor tracking: A retrospective treatment planning study

PURPOSE

For many thoracic tumors, patient respiration can introduce a significant amount of variability in tumor position that must be accounted for during radiotherapy. Of all existing techniques, real-time dynamic tumor tracking (DTT) represents the most ideal motion management strategy but can be limited by the treatment delivery technique. Our objective was to analyze the dosimetric performance of a dynamic conformal arc (DCA) approach to tumor tracking on standard linear accelerators that may offer similar dosimetric benefit, but with less complexity compared to intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT).

METHODS

Ten patients who previously received free-breathing VMAT for lung cancer were retrospectively analyzed. Patient 4D-CT and respiratory traces were simultaneously acquired prior to treatment and re-planned with DCA and VMAT using the Eclipse v15.6 Treatment Planning System with gated, deep inspiration breath hold (DIBH), and motion encompassment techniques taken into consideration, generating seven new plans per patient. DTT with DCA was simulated using an in-house MATLAB script to parse the radiation dose into each phase of the 4D-CT based on the patient's respiratory trace. Dose distributions were normalized to the same prescription and analyzed using dose volume histograms (DVHs). DVH metrics were assessed using ANOVA with subsequent paired t-tests.

RESULTS

The DCA-based DTT plans outperformed or showed comparable performance in their DVH metrics compared to all other combinations of treatment techniques while using motion management in normal lung sparing (p < 0.05). Normal lung sparing was not significantly different when comparing DCA-based DTT to gated and DIBH VMAT (p > 0.05), while both outperformed the corresponding DCA plans (p < 0.05). Simulated treatment times using DCA-based DTT were significantly shorter than both gating and DIBH plans (p < 0.05).

CONCLUSIONS

A DCA-based DTT technique showed significant advantages over conventional motion encompassment treatments in lung cancer radiotherapy, with comparable performance to stricter techniques like gating and DIBH while conferring greater time-saving benefits.

Respiratory management in the premature neonate

INTRODUCTION

Advances in neonatal care have made possible the increased survival of extremely preterm infants. Even though there is widespread recognition of the harmful effects of mechanical ventilation on the developing lung, its use has become imperative in the management of micro-/nano-preemies. There is an increased emphasis on the use of less-invasive approaches such as minimally invasive surfactant therapy and non-invasive ventilation that have been proven to result in improved outcomes.

AREAS COVERED

Here, we review the evidence-based practices surrounding the respiratory management of extremely preterm infants including delivery room interventions, invasive and non-invasive ventilation approaches, and specific ventilator strategies in respiratory distress syndrome and bronchopulmonary dysplasia. Adjuvant relevant respiratory pharmacotherapies used in preterm neonates are also discussed.

EXPERT OPINION

Early use of non-invasive ventilation and use of less invasive surfactant administration are key strategies in the management of respiratory distress syndrome in preterm infants. Ventilator management in bronchopulmonary dysplasia must be tailored according to the individual phenotype. There is strong evidence to start caffeine early to improve respiratory outcomes, but evidence is lacking on the use of other pharmacological agents in preterm neonates, and an individualized approach has to be considered for their use.

Respiratory management of spinal muscular atrophy type 1 patients treated with Nusinersen

INTRODUCTION

The recent development of disease-modifying treatments in spinal muscular atrophy (SMA) type 1 shifted these patients' management from palliative to proactive. The aim of this study was to assess patients' nocturnal gas exchanges before noninvasive ventilation (NIV) initiation and their clinical evolution to determine if capnia is a good criterion to decide when to introduce respiratory support.

PATIENTS AND METHODS

This multicentric retrospective study reports the respiratory management and evolution of 17 SMA type 1 children (10 females) for whom treatment with Nusinersen was initiated between 2016 and 2018.

RESULTS

Median [interquartile range-IQR] age at diagnosis and at first Nusinersen injection was of 4 [3;8] and 4 [3;9] months, respectively. Patients were followed during 38 [24;44] months. Thirteen (76%) patients were started on NIV at a median [IQR] age of 12 [9;18] months. Repeated hospitalizations and intensive care unit admissions were needed for 11 of them. Blood gas and nocturnal gas exchange recordings performed before NIV initiation were always normal. 9/13 X-ray performed before NIV showed atelectasis and/or acute lower respiratory tract infections. There was a significant decrease in the total number of hospital admissions between the first and second year of treatment (p = 0.04).

CONCLUSION

This study shows that patients do not present with nocturnal hypoventilation before respiratory decompensations and NIV initiation, and suggests that a delay in NIV initiation might result in respiratory complications. There is a need for disease-centered guidelines for the respiratory management of these patients, including NIV indications.

Procalcitonin is associated with postnatal respiratory condition severity in preterm neonate

INTRODUCTION

Postnatal respiratory failure is common in preterm neonates and is difficult to distinguish from early-onset neonatal bacterial infection by clinical symptoms. Similar to C-reactive protein (CRP), procalcitonin (PCT) is used as a marker of bacterial infection. Recently, it has been reported that the serum PCT levels increase because of respiratory failure immediately after birth. However, there is insufficient information concerning the relationship between biological inflammation markers, such as PCT and CRP, and postnatal respiratory condition severity.

METHODS

Preterm neonates were classified according to the received respiratory management as follows: nonrespiratory support (NRS), respiratory support (RS), surfactant administration therapy (STA), and STA with nitric oxide inhalation therapy (NO). The median serum PCT and CRP levels at 12-36 h postnatally were compared among the four groups. Additionally, the median serum PCT and CRP levels in the STA group were compared by STA timing and STA number.

RESULTS

The PCT levels for the NRS, RS, STA, and NO groups were 1.04, 6.46, 12.93, and 86.79 μg/L, respectively; the CRP levels were 0.40, 0.80, 1.10, and 16.40 mg/L, respectively. The PCT levels were significantly lower among neonates receiving STA in the birth subgroup (4.82 μg/L) than among those receiving STA in the admission subgroup (14.71 μg/L). The PCT levels were significantly higher among the STA multiple-dose subgroup (24.87 μg/L) than among the STA single-dose subgroup (12.47 μg/L). No significant differences in the CRP levels were observed.

CONCLUSION

The serum PCT levels in preterm neonates were associated with postnatal respiratory condition severity.

Pulmonary complications and respiratory management in neurocritical care: a narrative review

ABSTRACT

Neurocritical care (NCC) is not only generally guided by principles of general intensive care, but also directed by specific goals and methods. This review summarizes the common pulmonary diseases and pathophysiology affecting NCC patients and the progress made in strategies of respiratory support in NCC. This review highlights the possible interactions and pathways that have been revealed between neurological injuries and respiratory diseases, including the catecholamine pathway, systemic inflammatory reactions, adrenergic hypersensitivity, and dopaminergic signaling. Pulmonary complications of neurocritical patients include pneumonia, neurological pulmonary edema, and respiratory distress. Specific aspects of respiratory management include prioritizing the protection of the brain, and the goal of respiratory management is to avoid inappropriate blood gas composition levels and intracranial hypertension. Compared with the traditional mode of protective mechanical ventilation with low tidal volume (Vt), high positive end-expiratory pressure (PEEP), and recruitment maneuvers, low PEEP might yield a potential benefit in closing and protecting the lung tissue. Multimodal neuromonitoring can ensure the safety of respiratory maneuvers in clinical and scientific practice. Future studies are required to develop guidelines for respiratory management in NCC.

Trends in respiratory management of transferred very preterm infants in the last two decades

BACKGROUND

Among infants needing urgent transfer after birth, very preterm infants are a high-risk sub-group requiring special attention. This study aimed to assess trends in early respiratory management in a large series of very preterm infants undergoing postnatal transfer.

METHODS

Trends in patient characteristics and early respiratory management were assessed in 798 very preterm infants who were transferred by the Eastern Veneto Neonatal Emergency Transport Service in 2000-2019. Trends were analyzed using joinpoint regression analysis and summarized as annual percentage changes (APCs).

RESULTS

Proportion of neonates with birth weight less than 1 kg decreased from 33% to 16% (APC -3.82%). Use of nasal-continuous-positive-airway pressure increased (at call: APC 15.39%; during transfer: APC 15.60%), while use of self-inflating bag (at call: APC -12.09%), oxygen therapy (at call: APC -13.00%; during transfer: APC -23.77%) and mechanical ventilation (at call: APC -2.71%; during transfer: APC -2.99%) decreased. Use of oxygen concentrations at 21% increased (at call: APC 6.26%; during transfer: APC 7.14%), while oxygen concentrations above 40% decreased (at call: APC -5.73%; at transfer APC -8.89%). Surfactant administration at call increased (APC 3%-10%), while surfactant administration when arriving at referring hospital remained around 7-11% (APC 2.55%).

CONCLUSION

Relevant trends toward "gentle" approaches in early respiratory management of very preterm infants undergoing postnatal transfer occurred during the last twenty years. In addition, the proportion of transferred extremely low birth weight infants halved. Clinicians and stakeholders should consider such information when allocating assets to both hospitals and transfer services and planning regional perinatal programs.

Refined acquisition of high-resolution chest CTs in macaques by free breathing

The use of medical imaging as a non-invasive or minimally invasive method to assess disease or treatment response continues to grow. A similar trend is observed in pre-clinical research, in general, and more specifically in macaques, enabling longitudinal assessment of disease in individual animals. Computed tomography (CT) is such an imaging technique used to obtain clinically applicable data. To acquire a chest CT using a cone beam tomography system, some kind of respiration control is needed. A commonly used technique for this is endotracheal intubation and mechanical ventilation. However, although routinely performed this can increase the risk of impact on welfare in comparison with non-invasive imaging. Therefore, we studied the option of retrospectively gated CTs: acquiring high resolution chest CTs in freely breathing macaques. For this, we compared 748 CTs obtained during free breathing with 881 CTs obtained with mechanical ventilation in combination with a breath-hold procedure predominantly on the appearance of misregistration artifacts. The scans were obtained during different stages of multiple experimentally induced respiratory diseases. The comparison shows that although there are still streaking artifacts present in the retrospective gated scans, the amount of shading artifacts is reduced to such a level that it possibly dominates underlying lesions, causing misdiagnosis. Our data reveal that the use of retrospective gating in high resolution CTs for macaques can be successfully applied. With the use of this technique, artifacts due to free breathing are reduced to a diagnostically appropriate level. Most importantly, this technique makes chest CTs with this instrumentation a non-invasive modality.

The role of physiotherapy in the respiratory management of children with neuromuscular diseases: A South African perspective

Background

Respiratory morbidity is common in children with neuromuscular diseases (NMD) owing to chronic hypoventilation and impaired cough. Optimal, cost-effective respiratory management requires implementation of clinical practice guidelines and a coordinated multidisciplinary team approach.

Objectives

To explore South African physiotherapists’ knowledge, perception and implementation of respiratory clinical practice guidelines for non-ventilated children with NMD.

Methods

An online survey was conducted amongst members of the South African Society of Physiotherapy’s Cardiopulmonary Rehabilitation (CPRG) and Paediatric special interest groups and purposive sampling of non-member South African physiotherapists with respiratory paediatrics expertise (N= 481).

Results

Most respondents worked in private healthcare, with 1–10 years’ experience treating patients with NMD. For acute and chronic management, most participants recommended nebulisation and 24-h postural management for general respiratory care. Percussions, vibrations, positioning, adapted postural drainage, breathing exercises and manually assisted cough were favoured as airway clearance techniques. In addition, participants supported non-invasive ventilation, oscillatory devices and respiratory muscle training for chronic management.

Conclusion

Respondents seemed aware of internationally-endorsed NMD clinical practice guidelines and recommendations, but traditional manual airway clearance techniques were favoured. This survey provided novel insight into the knowledge, perspectives and implementation of NMD clinical practice guidelines amongst South African physiotherapists.

Clinical implications

There is an urgent need to increase the abilities of South African physiotherapists who manage children with NMD, as well as the establishment of specialised centres with the relevant equipment, ventilatory support and expertise in order to provide safe, cost-effective and individualised patient care.

The Japanese Medical Science Federation COVID-19 Expert Opinion English Version

In 2020, the COVID-19 pandemic has had unprecedented impacts on various aspects of the world. Each academic society has published a guide and/or guidelines on how to cope with COVID-19 separately. As the one and only nationwide association of academic societies that represent medical science in Japan, JMSF has decided to publish the expert opinion to help patients and care providers find specifically what they want. This expert opinion is a summary of recommendations by many academic societies and will be updated when necessary. Patients that each academic society targets differ even though they suffer from the same COVID-19, and recommendations can be different in a context-dependent manner. Readers are supposed to be flexible and adjustable when they use this expert opinion.

Respiratory Complications of Pediatric Neuromuscular Diseases

Respiration is an event of oxygen consumption and carbon dioxide production. Respiratory failure is common in pediatric neuromuscular diseases and the main cause of morbidity and mortality. It is a consequence of lung failure, ventilatory pump failure, or their combination. Lung failure often is due to chronic aspiration either from above or from below. It may lead to end-stage lung disease. Ventilatory pump failure is caused by increased respiratory load and progressive respiratory muscles weakness. This article reviews the normal function of the respiratory pump, general pathophysiology issues, abnormalities in the more common neuromuscular conditions and noninvasive interventions.

Late onset oxygen requirement following neonatal therapeutic hypothermia

AIM

To investigate the characteristics of infants with neonatal encephalopathy (NE) receiving therapeutic hypothermia (TH) who developed late onset oxygen requirement during or after rewarming.

METHODS

Infants were stratified by receiving (a) new onset isolated oxygen requirements during or after rewarming; (b) no respiratory support during hospital stay; and (c) invasive and/or non-invasive respiratory support before or during cooling.

RESULTS

Of 136 infants treated with TH, 49 (36%) did not require any respiratory support, and 78 (57.4%) received invasive or non-invasive support before or during cooling. Nine infants (6.6%) developed late onset oxygen requirement. The late onset oxygen requirement started at median age of 3.8 days (IQR 3.6-5.2) and ended at median 7.5 days (IQR 5.8-12.7). Total hours of O₂ exposure were median 62.0 (IQR 24.4-112.6). Maximum support was low-flow nasal cannula from 100% oxygen source with a flow rate of 40-250 mL/min. Infants in this group had higher Apgar scores, milder metabolic acidosis and no seizures. Three infants had diagnostic investigations without significant findings.

CONCLUSION

A small percentage of neonates with NE developed late onset oxygen requirement during or after rewarming. Late oxygen requirement was associated with evidence of less severe perinatal hypoxia-ischaemia.

Detectability of fiducials' positions for real-time target tracking system equipping with a standard linac for multiple fiducial markers

PURPOSE

To investigate the detectability of fiducial markers' positions for real-time target tracking system equipping with a standard linac. The hypothesis is that the detectability depends on the type of fiducial marker and the gantry angle of acquired triggered images.

METHODS

Three types of ball fiducials and four slim fiducials with lengths of 3 and 5 mm were prepared for this study. Triggered images with three similar fiducials were acquired at every 10° during the conformal arc irradiation to detect the target position. Although only one type of arrangement was prepared for the ball fiducials, a three-type arrangement was prepared for the slim fiducials, such as parallel, orthogonal, and oblique with 45° to the gantry-couch direction. To measure the detectability of the real-time target tracking system for each fiducial and arrangement, detected marker positions were compared with expected marker positions at every angle of acquired triggered images.

RESULTS

For the ball-type fiducial, the maximum difference between the detected marker positions and expected marker positions was 0.3 mm in all directions. For the slim fiducial arranged parallel and oblique with 45°, the maximum difference was 0.4 mm in all directions. When each slim fiducial was arranged orthogonal to the gantry-couch direction, the maximum difference was 1.5 mm for the length of 3 mm, and 3.2 mm for the length of 5 mm.

CONCLUSIONS

The detectability of fiducial markers' positions for the real-time target tracking system equipping with a standard linac depends on the form and insertion angles of the fiducials.

Use of high frequency jet ventilation as a refinement for imaging macaques with respiratory disease

Imaging is used in human medicine to diagnose disease and monitor treatment efficacy. Computed tomography (CT) positron emission tomography (PET) and magnetic resonance (MR) are applied to animal models of infectious diseases to increase data quality, enhance their relevance to the clinical situation, and to address ethical issues through reduction of numbers and refinement of study designs. The time required for collection of MR and PET-CT scans means that normal breathing produces motion artefacts that can render images unacceptable. We report, for the first time, the use of high frequency jet ventilation (HFJV) for respiratory management during imaging of macaques. HFJV enables continuous gaseous exchange, resulting in cessation of spontaneous breathing motion thus providing a motionless field without the potential stresses induced by repeated breath-hold strategies.

The effects of different positions on saturation and vital signs in patients

BACKGROUND

Patient positioning is an independent nursing intervention and may increase peripheral oxygenation for patients with lung disease. Few studies have been conducted on the effect of body positions on oxygenation in patients with lung disease.

AIMS AND OBJECTIVES

To investigate the effects of five different positions on peripheral oxygen saturation (SpO₂ ) and vital signs in patients with lung disease.

DESIGN

A semi-experimental study was conducted.

METHODS

Consecutive samples were recorded from critical care patients followed in the chest clinic of a university hospital. A total of 109 patients with lung disease were recruited. Patients who were able to lie in all positions, and who had unilateral or bilateral lung disease documented by a medical diagnosis by a physician were included in this study. The SpO₂ and vital signs were measured at each position three times.

RESULTS

For patients with right, left, and bilateral lung disease, lying on the right side of the body at 45 in bed, the SpO₂ was higher, but this difference was not statistically significant. There was a significant difference at 40 minutes between the pulse rate in patients with left and bilateral lung disease, but not in patients with right lung disease. No significant differences were found between respiratory rates and body temperature in patients in any of the three groups at 10, 25, and 40 minutes.

CONCLUSIONS

Although this difference was not statistically significant, lying on the right side of the body at 45 in bed can be an effective position for improving oxygenation in all patients with lung disease.

RELEVANCE TO CLINICAL PRACTICE

As there is insufficient evidence to suggest a specific position, further studies are needed. This study provides evidence that the best oxygenation in patients with unilateral and bilateral lung disease can be obtained by determining the appropriate position for critical care nurses.

Acute Effects of Mechanical Insufflation-Exsufflation on the Breathing Pattern in Stable Subjects With Duchenne Muscular Dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is characterized by progressive degeneration, wasting, and weakness of skeletal musculature, including respiratory muscles. Cough is also compromised with disease progression. Among cough-augmentation techniques, mechanical insufflation-exsufflation (MI-E) has demonstrated several clinical benefits in patients with chronic airway secretion obstruction and muscular weakness. In clinical practice, the use of MI-E in DMD patients is also suggested when they are stable with no airway infections. However, there is a paucity of studies that consider the effect of MI-E specifically on stable DMD patients who have adapted to the use of MI-E.

METHODS

Twenty subjects with DMD with no active upper airway or lung infections, who used MI-E device regularly at home, were enrolled. They received a single MI-E treatment consisting of 5 cycles of 5 insufflations-exsufflations with their customary settings. Volume variations during quiet breathing, vital capacity, and cough before and after treatment were measured with optoelectronic plethysmography (OEP).

RESULTS

A decrease in breathing frequency (P = .001) and the rapid shallow breathing index emerged (P = .007), while cough peak flow (Spirometer P = .86, OEP P = .58), vital capacity (Spirometer P = .78, OEP total chest wall P = .57), and end-expiratory volumes (Total chest wall P = .97, Ribcage P = .14, Abdomen P = .10) were not affected by the treatment. An increment of the chest wall volume variation during the expiratory cough phase was identified (P = .001), particularly due to an increase in abdominal expansion (P = .005).

CONCLUSIONS

A single treatment of MI-E in subjects with stable DMD already adapted to the device can provide beneficial changes in breathing pattern through a significant decrease in breathing frequency and rapid shallow breathing. These findings suggest an improvement in short-term dyspnea, although there were no changes in lung-volume recruitment or unassisted cough peak flow.

Management Practice and Mortality for Infants with Congenital Diaphragmatic Hernia

OBJECTIVE

Congenital diaphragmatic hernia (CDH) is fatal in 20 to 40% of cases, largely due to pulmonary dysmaturity, lung hypoplasia, and persistent pulmonary hypertension. Evidence for survival benefit of inhaled nitric oxide (iNO), extracorporeal membrane oxygenation (ECMO), and other medical interventions targeting pulmonary hypertension is lacking. We assessed medical interventions and mortality over time in a large multicenter cohort of infants with CDH.

STUDY DESIGN

We identified all infants ≥ 34 weeks' gestation with CDH discharged from 29 neonatal intensive care units between 1999 and 2012 with an average of ≥ 2 CDH admissions per year. We examined mortality and the proportion of infants exposed to medical interventions, comparing four periods of time: 1999-2001, 2002-2004, 2005-2007, and 2008-2012.

RESULTS

We identified 760 infants with CDH. From 1999-2001 to 2008-2012, use of iNO increased from 20% of infants to 50%, sildenafil use increased from 0 to 14%, and milrinone use increased from 0 to 22% (p < 0.001). Overall mortality (28%) did not significantly change over time compared with the earliest time period.

CONCLUSION

Despite changing use of iNO, sildenafil, and milrinone, CDH mortality has not significantly decreased in this population of infants.

Clinical Decision Support and Closed-Loop Control for Cardiopulmonary Management and Intensive Care Unit Sedation Using Expert Systems

Patients in the intensive care unit (ICU) who require mechanical ventilation due to acute respiratory failure also frequently require the administration of sedative agents. The need for sedation arises both from patient anxiety due to the loss of personal control and the unfamiliar and intrusive environment of the ICU, and also due to pain or other variants of noxious stimuli. While physicians select the agent(s) used for sedation and cardiovascular function, the actual administration of these agents is the responsibility of the nursing staff. If clinical decision support systems and closed-loop control systems could be developed for critical care monitoring and lifesaving interventions as well as the administration of sedation and cardiopulmonary management, the ICU nurse could be released from the intense monitoring of sedation, allowing her/him to focus on other critical tasks. One particularly attractive strategy is to utilize the knowledge and experience of skilled clinicians, capturing explicitly the rules expert clinicians use to decide on how to titrate drug doses depending on the level of sedation. In this paper, we extend the deterministic rule-based expert system for cardiopulmonary management and ICU sedation framework presented in [1] to a stochastic setting by using probability theory to quantify uncertainty and hence deal with more realistic clinical situations.

Average volume-assured pressure support in a 16-year-old girl with congenital central hypoventilation syndrome

Congenital central hypoventilation syndrome (CCHS) is an uncommon disorder characterized by the absence of adequate autonomic control of respiration, which results in alveolar hypoventilation and decreased sensitivity to hypercarbia and hypoxemia, especially during sleep. Patients with CCHS need lifelong ventilatory support. The treatment options for CCHS include intermittent positive pressure ventilation administered via tracheostomy, noninvasive positive pressure ventilation, negative-pressure ventilation by body chamber or cuirass, and phrenic nerve pacing. However, it may be necessary to alter the mode of ventilation according to age, psychosocial reasons, complications of therapy, and emergence of new modes of ventilation. We present a case of a 16-year-old girl with CCHS who was mechanically ventilated via tracheostomy for 16 years and was successfully transitioned to a new modality of noninvasive ventilation (average volume-assured pressure support [AVAPS]) that automatically adjusts the pressure support level in order to provide a consistent tidal volume.