Negative Inspiratory Pressure Research Articles

Hemoptysis due to severe obstructive sleep apnea

Although OSA is rarely mentioned as a clinically relevant differential diagnosis of hemoptysis in the literature, we report on a patient with chronic hemoptysis, which was caused by repetitive intrathoracic negative pressures due to severe upper airway obstruction.A 56-year-old overweight patient (BMI 32 kg/m2), with a long history of smoking (40 PY) and who complained of pronounced daytime sleepiness, was referred 2 years ago in March and last year in the summer to our emergency room because of long lasting mild hemoptysis.Sedation during bronchoscopies induced hypopharyngeal collapse accompanied by severe obstructive apneas and massive inspiratory negative pressure. Simultaneously, multiple petechial and larger flat mucosal bleeding as fresh blood coverings occurred on the bronchial mucosa. At the first presentation, the patient wished no further diagnosis. During the second presentation, polysomnography including transcutaneous CO2 measurement showed a severe OSA in combination with hypoventilation (AHI of 76/h, desaturation index: 128/h; medium PCO2 value of 56 mmHg). OSA was treated effectively with oronasal positive pressure.With this case report we underline the generally underestimated implication of strong intrathoracic negative pressures in severe OSA as a clinically relevant differential diagnosis of hemoptysis.

Pharyngeal Manometry and Upper Airway Collapse During Drug-Induced Sleep Endoscopy

Drug-induced sleep endoscopy (DISE) is used to guide therapeutic management of obstructive sleep apnea (OSA), depending on the levels and patterns of pharyngeal collapse. However, the collapsibility of specific pharyngeal sites remains unknown. To assess collapse sites in patients with OSA undergoing DISE and whether number and location are associated with differences in airway collapsibility; and to quantify differences in collapsibility between primary and secondary sites in multilevel collapse. This cohort study assessed adult patients (≥18 years) with OSA undergoing DISE with manometry and positive airway pressure (PAP) titration at a tertiary care center from November 2021 to November 2023. Patients with an AHI score greater than 5 were included; those with less than 1 apnea event during DISE or incorrect catheter placement were excluded. Data were analyzed from September 28, 2022, to March 31, 2024. DISE with manometry and PAP titration. Active pharyngeal critical pressure (Pcrit-A) and pharyngeal opening pressure (PhOP) were used to quantify airway collapsibility, adjusted for covariates (age, sex, race, and body mass index [BMI]). Of 94 screened, 66 patients (mean [SD] age, 57.4 [14.3] years; BMI, 29.2 [3.9]; 51 [77.3%] males) with a mean (SD) apnea-hypopnea index (AHI) of 31.6 (19.0) were included in the analysis. Forty-seven patients (71.2%) had multilevel collapse, 10 (15.2%) had single-level nasopalatal collapse, and 9 (13.6%) had single-level infrapalatal collapse. Groups did not differ in demographic characteristics or established measures of OSA severity. The single-level nasopalatal group had substantially elevated levels of airway collapsibility (Pcrit-A and PhOP covariate adjusted mean, 2.4; 95% CI, 1.1 to 3.8; and 8.2; 95% CI, 6.4 to 9.9 cmH2O) compared to the single-level infrapalatal group (-0.9; 95% CI, -2.4 to 0.5 cmH2O; and 4.9; 95% CI, 3.0 to 6.8 cmH2O, respectively) and similar to the level among the multilevel group (1.3; 95% CI, 0.7 to 2.0; and 8.5; 95% CI, 7.7 to 9.3 cmH2O). The multilevel group had more negative inspiratory pressure (-24.2; 95% CI, -28.1 to -20.2 cmH2O) compared to the single-level nasopalatal group (-9.8; 95% CI, -18.3 to -1.28 cmH2O). In patients with multilevel collapse, airway collapsibility was significantly higher at the primary nasopalatal compared to secondary infrapalatal site (mean difference, 13.7; 95% CI, 11.3 to 16.1 cmH2O). The findings of this cohort study suggest that intervention should target the primary site of pharyngeal collapse, and secondary sites only if they are nearly as collapsible as the primary site. Future work is needed to precisely define the difference in primary and secondary collapsibility that necessitates multilevel treatment.

Traumatic nasogastric intubation as a suspected cause of laryngeal obstruction in a horse recovering from emergency laparotomy

AbstractAn 18‐year‐old mare, admitted for colic, underwent an exploratory laparotomy for right dorsal colon displacement. During recovery from anaesthesia, a severe acute onset laryngeal obstruction occurred at standing, requiring orotracheal re‐intubation, which relieved the obstruction. This was followed by secondary pulmonary oedema, treated with furosemide (2 mg/kg intravenously) and oxygen. At re‐extubation, attempted 30 minutes later, the horse re‐obstructed immediately and collapsed, prompting an emergency tracheostomy. Furosemide (2 mg/kg intravenously) and dexamethasone (0.1 mg/kg intravenously) were also administered. The horse stood up thereafter with a patent airway. In the history, to note, nasogastric intubation was particularly difficult at admission, and was identified as a potential cause of laryngeal trauma that may have precipitated laryngeal obstruction due to severe local inflammation. Dynamic laryngeal collapse probably also played a role due to high inspiratory negative pressure generated at the precise timing of standing, similar to exercise.

Dynamic nasopharyngeal collapse in horses: What we know so far.

Dynamic nasopharyngeal collapse (NPC) is an obstructive upper airway disease that affects mainly the inspiratory phase of respiration in horses undergoing strenuous exercise. It occurs when the neuromuscular activity of the nasopharynx is overwhelmed by the intense negative pressures generated during exercise. This leads to collapse of at least one of the four components of the nasopharynx which is comprised of the two lateral walls, the dorsal roof and the ventral soft palate. As a result, the airway diameter and thus airflow become compromised. Even small changes in the airway diameter produces profound increases in negative inspiratory pressure, perpetuating the cycle of collapse. Compared to other dynamic upper respiratory tract disorders, the amount of literature on NPC as a disease entity is limited. The exact pathophysiology of NPC is unknown; however, it impacts up to one quarter of high-performance equine athletes presenting for poor performance. There is currently no definitive treatment for this severely performance-limiting condition. Thus, the prognosis for future athletic prognosis is guarded, with most horses being retired from racing or athletic use in general. Further research is warranted in this field to reduce the impact of disease and in turn, reduce the turnover rate and economic loss by enhancing the career longevity of elite equine athletes diagnosed with NPC.

Forced inspiratory suction and swallow tool (FISST): an automation of Valsalva maneuver variants for therapeutic interventions

ABSTRACT Introduction The Valsalva maneuver and its modifications have been utilized across several conditions in medicine; however, there have been difficulties in its application. Thus, at the University of Texas Health Science Center in San Antonio, we designed and patented an affordable and accessible device that mimics Valsalva called “Forced Inspiratory Suction and Swallow Tool (FISST). Areas Covered In this review, we discuss the premise for the design of FISST, based on applications of the law of conservation energy, the continuity equation, and Bernoulli’s principle. We then detail the mechanism by which FISST stimulates hiccup cessation by increasing negative inspiratory pressure when drinking through the apparatus, causing diaphragmatic contraction and disruption of the hiccup reflex. We then detail the efficacy and future applications of FISST in addressing other pathologies. Expert Opinion FISST has been used to address hiccups by utilizing its reverse-Valsalva effect to increase parasympathetic stimulation by increasing vagal tone. In a prospective study that we conducted on a cohort of 249 hiccup subjects worldwide, this tool achieved 92% effectiveness. Additionally, several cases, including a published case report, have found FISST successful in terminating supraventricular tachycardias (SVT). FISST may be further utilized in diagnosing or addressing various upper airway pathologies and should be explored further.

Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) is the most common type of sleep-disordered breathing. This article describes advances in the diagnosis, testing, treatment, and monitoring of OSA. Home sleep apnea testing and in-laboratory polysomnography are the most commonly used diagnostic tools in the identification and monitoring of OSA, but new methods for diagnosis and at-home monitoring of treatment response are being developed and validated. While the apnea-hypopnea index is regularly used to define OSA severity, recognition is increasing of its inability to risk-stratify patients. Other sleep study data including arousal threshold, hypoxic burden, and pulse rate variability as well as clinical characteristics can help with risk stratification. The most effective treatment is continuous positive airway pressure (CPAP), which can be limited by adherence and tolerance in some patients. Newer masks and comfort features including heated tubing and expiratory pressure relief may improve tolerance to positive airway pressure (PAP) therapy. Additional treatment options include other PAP modalities, mandibular advancement devices, tongue stimulation therapy, negative inspiratory pressure, nasal expiratory pressure valves, nasal congestion treatments, upper airway surgeries including hypoglossal nerve stimulation, and medications. OSA is a common disorder that causes sleep and daytime symptoms and increases the risk of neurologic and medical complications. Neurologists should be aware of atypical presentations and understand the diagnostic and treatment options.

Exposure of inspiratory negative pressure breathing on cosmonauts during spaceflight

The aim of our study was to investigate the effects of inspiratory negative pressure breathing (NPBin) via impedance threshold device on breathing pattern and body fluid distribution in cosmonauts during spaceflight. The lung function (volumes and flows, breath-hold time) was estimated in details before NPBin exposure as well. The 16 cosmonauts participated in study on ISS board: they were examined before, during spaceflight and after landing. All cosmonauts included in the study were well trained for providing the experimental procedure by themselves. The mask with impedance threshold (−20 cm H2O on inhale) was used. Breathing rate, intramask pressure and electrical impedance of head, body and limbs have been monitoring before (5 min) and during NPBin (20 min). The obtained data has shown no significant differences in lung volumes and flows in comparison of preflight and spaceflight values. Generally, NPBin led to significant decrease of breathing rate. No statistically significant changes in electrical impedance of body and head at NPBin compared with tidal breathing were found. The effectiveness of NPBin as a preventing means for fluid shifts in cosmonauts (astronauts) during spaceflight is discussed and needs the further studies.

Physiological respiratory parameters in pre-hospital patients with suspected COVID-19: A prospective cohort study.

The COVID-19 pandemic has presented emergency medical services (EMS) worldwide with the difficult task of identifying patients with COVID-19 and predicting the severity of their illness. The aim of this study was to investigate whether physiological respiratory parameters in pre-hospital patients with COVID-19 differed from those without COVID-19 and if they could be used to aid EMS personnel in the prediction of illness severity. Patients with suspected COVID-19 were included by EMS personnel in Uppsala, Sweden. A portable respiratory monitor based on pneumotachography was used to sample the included patient's physiological respiratory parameters. A questionnaire with information about present symptoms and background data was completed. COVID-19 diagnoses and hospital admissions were gathered from the electronic medical record system. The physiological respiratory parameters of patients with and without COVID-19 were then analyzed using descriptive statistical analysis and logistic regression. Between May 2020 and January 2021, 95 patients were included, and their physiological respiratory parameters analyzed. Of these patients, 53 had COVID-19. Using adjusted logistic regression, the odds of having COVID-19 increased with respiratory rate (95% CI 1.000-1.118), tidal volume (95% CI 0.996-0.999) and negative inspiratory pressure (95% CI 1.017-1.152). Patients admitted to hospital had higher respiratory rates (p<0.001) and lower tidal volume (p = 0.010) compared to the patients who were not admitted. Using adjusted logistic regression, the odds of hospital admission increased with respiratory rate (95% CI 1.081-1.324), rapid shallow breathing index (95% CI 1.006-1.040) and dead space percentage of tidal volume (95% CI 1.027-1.159). Patients taking smaller, faster breaths with less pressure had higher odds of having COVID-19 in this study. Smaller, faster breaths and higher dead space percentage also increased the odds of hospital admission. Physiological respiratory parameters could be a useful tool in detecting COVID-19 and predicting hospital admissions, although more research is needed.

A new approach to improve the hemodynamic assessment of cardiac function independent of respiratory influence

Cardiovascular and respiratory systems are anatomically and functionally linked; inspiration produces negative intrathoracic pressures that act on the heart and alter cardiac function. Inspiratory pressures increase with heart failure and can exceed the magnitude of ventricular pressure during diastole. Accordingly, respiratory pressures may be a confounding factor to assessing cardiac function. While the interaction between respiration and the heart is well characterized, the extent to which systolic and diastolic indices are affected by inspiration is unknown. Our objective was to understand how inspiratory pressure affects the hemodynamic assessment of cardiac function. To do this, we developed custom software to assess and separate indices of systolic and diastolic function into inspiratory, early expiratory, and late expiratory phases of respiration. We then compared cardiac parameters during normal breathing and with various respiratory loads. Variations in inspiratory pressure had a small impact on systolic pressure and function. Conversely, diastolic pressure strongly correlated with negative inspiratory pressure. Cardiac pressures were less affected by respiration during expiration; late expiration was the most stable respiratory phase. In conclusion, inspiration is a large confounding influence on diastolic pressure, but minimally affects systolic pressure. Performing cardiac hemodynamic analysis by accounting for respiratory phase yields more accuracy and analytic confidence to the assessment of diastolic function.

Assessment of diaphragmatic excursion-time index as a predictor of successful weaning from mechanical ventilation

Background and aim Timing is essential for real weaning from mechanical ventilation as unfavorable weaning may provoke extended cardiovascular, respiratory-pressing factor, carbon dioxide retention, and hypoxemia. The mark of the current examination was to review the accuracy of diaphragmatic excursion-time index assessed by ultrasound as a predictor of successful weaning from mechanical ventilation. Patients and methods This is a prospective cohort study. It was done in the University Hospitals during the period from October 2019 to March 2020. Results This study was done on 36 patients over 18 years of age precisely ventilated for over 48 h legible for the beginning of weaning from mechanical ventilation. After endorsement of Institutional Ethical Committee, a written informed consent was obtained from every tolerant's family member. Patients were arbitrarily assigned into two equivalent groups: group 1: successful weaning thought about when supported spontaneous breathing without invasive or noninvasive mechanical support for over 48 h following extubation and group 2: failed weaning when the patient needs reintubation, noninvasive ventilation, or required tracheostomy within 48 h after extubation. Conclusions Ultrasound-guided diaphragmatic excursion-time index measured either at the beginning of spontaneous breathing trial or before extubation was the stronger predictor of successful weaning from mechanical ventilation compared with diaphragmatic excursion, rapid shallow breathing index, and negative inspiratory pressure.

Immersion pulmonary edema: an analysis of 31 cases from Oceania

To review incidents of immersion pulmonary edema (IPE) from Oceania, to determine the demographics, diving parameters, and comorbidities that may be related to this disorder. Incidents of IPE, most of which were documented by Divers Alert Network Asia-Pacific (DAN AP) or reported in our medical literature, were analyzed. They included interviews with the survivors and a review of available medical records. Only incidents diagnosed as IPE by specialist diving physicians or pathologists with experience in the investigation of diving accidents were included. Thirty-one IPE incidents in divers from Oceania were documented. There were two surface snorkelers, 22 scuba air divers and seven nitrox divers, which included three closed-circuit rebreathers (CCR). The mean (SD) age was 53 (12) years, 58% of victims were females, and the average dive profile was to a maximum depth of 19 msw for 25 minutes. Six victims (19%) had previous episodes of IPE. There were nine recorded fatalities in this cohort. Medical comorbidities were recorded in 68%, with 42% being cardiac. The latter included valvular disease in 29%, transient cardiomyopathies in 26% and dysrhythmias in 16%. IPE was more likely in middle-aged females, in experienced divers, and during ascent or after surfacing. Commonly reported associations such as exertion, stress, cold exposure, negative inspiratory pressure, hypertension, overhydration, tight wetsuit, aspiration and certain medications were identified. This series supports the hypothesis that the elderly IPE subjects are likely to have comorbidities and be susceptible to IPE recurrences and fatalities unless the contributing factors can be identified and addressed.

Immersion pulmonary edema: case reports from Oceania

We aimed to document identified cases of immersion pulmonary edema (IPE) in divers from Oceania (the Indo-Pacific region) from January 2002 to May 2018, inclusive. Cases were identified using various sources, including searches of the Divers Alert Network Asia-Pacific (DAN AP) Fatality Database, published case reports, and interviews with survivors who had reported their incident to DAN AP. Where available, investigations, pathology and autopsy results were obtained. Only incidents diagnosed as IPE by diving physicians or pathologists with experience in the investigation of diving accidents were included. Individual case histories and outcomes, together with brief individual summaries of the associations and possible contributing factors were recorded. Thirty-one IPE incidents in divers from Oceania were documented. There were two surface snorkelers, 22 scuba air divers and seven nitrox divers which included three closed-circuit rebreathers (CCR). The mean (SD) age was 53 (12) years, 58% of victims were females, and the average dive profile was to a maximum depth of 19 meters of seawater for 25 minutes. Six victims (19%) had previous episodes of IPE. There were nine recorded fatalities. Cardiac anomalies dominated the associated or possible contributing factors. These included valvular disease in 29%, transient cardiomyopathies in 26% and dysrhythmias in 16%. Previously reported associations of IPE such as exertion, stress, cold exposure, negative inspiratory pressure, hypertension, overhydration, ascent or surfacing, tight wetsuit, aspiration and certain medications were identified. Cardiac conditions were frequent and included chronic disorders (valvular pathology, coronary artery disease) and transient disorders (dysrhythmias, transient myocardial dysfunction, takotsubo or stress cardiomyopathy). It is likely that the chronic cardiac disorders may have contributed to the IPE, whereas the transient cases could be either sequelae, contributors or coincidental to the IPE.

Ramsay Sedation Scale Project: Small, Easy Changes for a Big Effect on Patient Safety.

Ramsay Sedation Scale Project: Small, Easy Changes for a Big Effect on Patient Safety.

Impaired central hemodynamics in chronic obstructive pulmonary disease during submaximal exercise.

It is unknown whether central hemodynamics are impaired during exercise in chronic obstructive pulmonary disease (COPD) patients. We hypothesized that, at a similar absolute V̇o2 during exercise, COPD patients would have a lower stroke volume and cardiac output compared with healthy controls. Furthermore, we hypothesized that greater static hyperinflation [ratio of inspiratory capacity to total lung capacity (IC/TLC)] and expiratory intrathoracic pressure would be significantly related to the lower cardiac output and stroke volume responses in COPD patients. Clinically stable COPD (n = 13; FEV1/FVC: 52 ± 13%) and controls (n = 10) performed constant workload submaximal exercise at an absolute V̇o2 of ~1.3 L/min. During exercise, inspiratory capacity maneuvers were performed to determine operating lung volumes and cardiac output (via open-circuit acetylene rebreathe technique) and esophageal pressure were measured. At similar absolute V̇o2 during exercise (P = 0.81), COPD had lower cardiac output than controls (COPD: 11.0 ± 1.6 vs. control: 12.2 ± 1.2 L/min, P = 0.03) due to a lower stroke volume (COPD: 107 ± 13 vs. control: 119 ± 19 mL, P = 0.04). The heart rate response during exercise was not different between groups (P = 0.66). FEV1 (%predicted) and IC/TLC were positively related to stroke volume (r = 0.68, P = 0.01 and r = 0.77, P < 0.01). Last, esophageal pressure-time integral during inspiration was positively related to cardiac output (r = 0.56, P = 0.047). These data demonstrate that COPD patients have attenuated cardiac output and stroke volume responses during exercise compared with control. Furthermore, these data suggest that the COPD patients with the most severe hyperinflation and more negative inspiratory intrathoracic pressures have the most impaired central hemodynamic responses.NEW & NOTEWORTHY Chronic obstructive pulmonary disease leads to cardiac structural changes and pulmonary derangements that impact the integrative response to exercise. However, it is unknown whether these pathophysiological alterations influence the cardiac response during exercise. Herein, we demonstrate that COPD patients exhibit impaired central hemodynamics during exercise that are worsened with greater hyperinflation.

Metered-dose inhaler therapy with spacers: Are newborns capable of using this system correctly?

Aerosol therapy using a metered-dose inhaler (MDI) coupled to a spacer chamber is the most widely used long-term treatment modality for chronic lung disease of prematurity. However, its use in neonates is based on data obtained from other age groups. Proper use of maintenance treatment is essential for the long-term stability of these patients. To ascertain whether newborns are capable of generating negative pressure during the use of a spacer with face mask for aerosol therapy. Total of 117 low-risk newborns (age 12-48 hours), with no congenital malformations or any detectable clinical symptoms, were included. Inspiratory pressure was measured with a respiratory pressure meter, at each respiratory cycle, during a 10-second period, for three sequential measurements. The meter was connected to the inner chamber of the spacer through a noncollapsible silicone tube. Suitably sized masks were used. Only 43 participants (36.8%) generated a negative pressure capable of opening the spacer valve, as verified by the respiratory pressure meter. In 25 patients, all three measurements were within the expected range. Weight, gestational age, and mode of delivery were in no way associated with the ability to generate a detectable negative pressure. In neonates, the MDI therapy with a spacer chamber and face mask is susceptible to failure due to the inability of most patients in this age range to generate a negative inspiratory pressure sufficient to open the spacer valve.

The Case Files

The Case Files

Predictors of failure of early shift from invasive to noninvasive ventilation in weaning chronic obstructive pulmonary disease patients who have failed the initial spontaneous breathing trial: a prospective cohort study

ContextNoninvasive ventilation (NIV) is a well-established modality for difficult and prolonged weaning of chronic obstructive pulmonary disease (COPD) patients. Although several studies have addressed the early shifting to NIV, predictors of its success remain to be determined.AimsThe aim of the study was to find predictors of success of early shift of COPD patients who have failed the spontaneous breathing trail (SBT) to NIV.Design and settingsThis investigation was designed as a double-centered prospective cohort study involving the ICUs of Critical Care Medicine of Cairo University and Shebin El-Kom Teaching Hospital.Patients and methodsConsecutive COPD patients who failed the initial SBT were extubated and shifted to NIV. We compared arterial blood gases, lung mechanics, and spontaneous breathing parameters in successful patients with these parameters in those who failed the early shift to NIV.ResultsOut of the 30 patients, 21 (70%) were successfully weaned by early shift to NIV. The failed group had a significantly higher autopositive end-expiratory pressure (P<0.001), rapid shallow breathing index (RSBI) (P<0.05), and significantly lower static compliance and negative inspiratory pressure (NIP) (P<0.001) on admission.Admission RSBI and NIP were the only predictors of failure of early shift to NIV. Just before SBT, the failed group had a significantly higher autopositive end-expiratory pressure (P<0.001), RSBI (P<0.001), and airway resistance (Raw) (P<0.001) and significantly lower static compliance, NIP, and PO2/FIO2 (P/F) ratio. Raw and NIP before SBT were the only predictors of success of early shift to NIV.ConclusionRSBI, NIP, and Raw, rather than arterial blood gases, are the most important predictors for success of early shift to NIV in COPD patients who have failed the initial SBT.

Predictors of failure of early shift from invasive to noninvasive ventilation in weaning chronic obstructive pulmonary disease patients who have failed the initial spontaneous breathing trial: a prospective cohort study

Noninvasive ventilation (NIV) is a well-established modality for difficult and prolonged weaning of chronic obstructive pulmonary disease (COPD) patients. Although several studies have addressed the early shifting to NIV, predictors of its success remain to be determined. The aim of the study was to find predictors of success of early shift of COPD patients who have failed the spontaneous breathing trail (SBT) to NIV. This investigation was designed as a double-centered prospective cohort study involving the ICUs of Critical Care Medicine of Cairo University and Shebin El-Kom Teaching Hospital. Consecutive COPD patients who failed the initial SBT were extubated and shifted to NIV. We compared arterial blood gases, lung mechanics, and spontaneous breathing parameters in successful patients with these parameters in those who failed the early shift to NIV. Out of the 30 patients, 21 (70%) were successfully weaned by early shift to NIV. The failed group had a significantly higher autopositive end-expiratory pressure (P<0.001), rapid shallow breathing index (RSBI) (P<0.05), and significantly lower static compliance and negative inspiratory pressure (NIP) (P<0.001) on admission. Admission RSBI and NIP were the only predictors of failure of early shift to NIV. Just before SBT, the failed group had a significantly higher autopositive end-expiratory pressure (P<0.001), RSBI (P<0.001), and airway resistance (Raw) (P<0.001) and significantly lower static compliance, NIP, and PO2/FIO2 (P/F) ratio. Raw and NIP before SBT were the only predictors of success of early shift to NIV. RSBI, NIP, and Raw, rather than arterial blood gases, are the most important predictors for success of early shift to NIV in COPD patients who have failed the initial SBT.

Fluid Balance Is Associated with Clinical Outcomes and Extravascular Lung Water in Children with Acute Asthma Exacerbation.

The effects of fluid administration during acute asthma exacerbation are likely unique in this patient population: highly negative inspiratory intrapleural pressure resulting from increased airway resistance may interact with excess fluid administration to favor the accumulation of extravascular lung water, leading to worse clinical outcomes. Investigate how fluid balance influences clinical outcomes in children hospitalized for asthma exacerbation. We analyzed the association between fluid overload and clinical outcomes in a retrospective cohort of children admitted to an urban children's hospital with acute asthma exacerbation. These findings were validated in two cohorts: a matched retrospective and a prospective observational cohort. Finally, ultrasound imaging was used to identify extravascular lung water and investigate the physiological basis for the inferential findings. In the retrospective cohort, peak fluid overload [(fluid input - output)/weight] is associated with longer hospital length of stay, longer treatment duration, and increased risk of supplemental oxygen use (P values < 0.001). Similar results were obtained in the validation cohorts. There was a strong interaction between fluid balance and intrapleural pressure: the combination of positive fluid balance and highly negative inspiratory intrapleural pressures is associated with signs of increased extravascular lung water (P < 0.001), longer length of stay (P = 0.01), longer treatment duration (P = 0.03), and increased risk of supplemental oxygen use (P = 0.02). Excess volume administration leading to fluid overload in children with acute asthma exacerbation is associated with increased extravascular lung water and worse clinical outcomes.

Respiratory Dysfunction in Spinal Cord Injury: Physiologic Changes and Clinically Relevant Therapeutic Applications

Spinal cord injury (SCI) can result in serious respiratory compromise, impaired cough ability and respiratory failure. Complications include atelectasis and pneumonia. Respiratory failure is the primary cause of morbidity and mortality in high cervical cord injuries. Various methods have been used to assist coughing in SCI, including manual and mechanical techniques. Physical therapists can apply certain exercises and maneuvers to augment tidal breathing and expiratory effort, such as respiratory muscle training. For patients with vital capacities <10 to 15 mL/ kg, noninvasive methods such as abdominal binding, the pneumobelt, and face mask-applied ventilators are used to maintain adequate respiration. Phrenic nerve and diaphragmatic pacing provide increased patient mobility, comfort and lower health care costs; breathing pacemakers have increased survival and improved quality of life in individuals with upper cervical cord and brain stem lesions. Tracheostomy should be used only for those patients that have severe bulbar impairment and cannot successfully use airway clearance methods. Even patients with tracheostomyassisted ventilation can be eventually weaned off respirators, provided they meet criteria for spontaneous breathing. Peak expiratory flows should exceed 160 L/m to assure expulsion of airway secretions and the negative inspiratory pressure should exceed -20 cm H2O (variables measured with the tube cuff inflated) before the patient is decannulated. Appropriate vaccinations should be provided for any individual with compromised respiratory function, particularly with regularly scheduled influenza and pneumococcal pneumonia vaccines. Management of the physically impaired patient can be a major challenge for family, leading to adverse physical and psychological consequences. Long-term management requires a multidisciplinary approach that includes respiratory, physical and occupational therapists, nutritionists, social workers, psychologists, and home health agencies, all of whom contribute to key aspects of maintaining optimum respiratory function. Life satisfaction is a major consideration in this group of individuals, but it may have a more positive outlook than one would think in someone with significant physical and psychological challenges.