Respiratory management of the cardiovascular surgical patient.
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Auto-PEEP (A-PEEP), unrecognized alveolar positive and expiratory pressure during mechanical ventilation, is an acknowledged hazard in patients with chronic obstructive lung disease. We evaluated 50 consecutive trauma patients for the presence of A-PEEP and its effect on hemodynamic stability. Injury Severity Scores (ISS) were 8 to 41 (21 +/- 1); Revised Trauma Scores (RTS) ranged from 2.0 to 7.8 (6.2 +/- 0.2). Mode of ventilation was assist control, inspiratory flow rates were 40 to 120 L/M (78 +/- 2). A-PEEP, determined in the non-assisting patient by occluding the expiratory port at end exhalation, was present in 28 patients (56%) and ranged from 1 to 12 cm H2O (5.3 +/- 0.4 cm H2O). Data segregated by A-PEEP versus no A-PEEP were as follows (Mean +/- SEM): [table: see text] *P less than 0.05, VE = minute ventilation, Paw = mean airway pressure. Upon reversal of A-PEEP in the eight patients with levels greater than 5 cm H2O, mean blood pressure rose from 90 +/- 17 to 102 +/- 22 mm Hg and central venous pressure fell from 13 +/- 5 to 7 +/- 5 mm Hg. A-PEEP was successfully treated in these eight patients by increasing peak flows, minimizing VE requirements and selective use of bronchodilators. In sum, the hypermetabolic ventilated trauma patient should be monitored routinely for this common phenomenon which may have profound cardiopulmonary effects in the setting of acute resuscitation.
Home oxygen and ventilation therapies are used to treat children who have varying degrees of chronic respiratory insufficiency from many causes. Potential sequelae to even mild or intermittent respiratory insufficiency have been identified. Infants with bronchopulmonary dysplasia who still require oxygen can be discharged earlier from hospitals with appropriate discharge planning and family support. Children with progressive diseases may eventually require oxygen or ventilation therapies to improve the duration or quality of their lives. Obstructive sleep apnea has been treated with supplemental oxygen and nasal continuous positive airway pressure. Guidelines exist for initiation and home management of oxygen and invasive or noninvasive mechanical ventilation.
Perfluorochemical liquid has been used experimentally to enhance mechanical ventilation for the past 30 years. Liquid ventilation is one of the most extensively studied revolutionary medical therapies being considered for use in practice. Since 1989, when the first human neonates were treated with perfluorochemical liquid, more than 500 human patients--neonate, pediatric, and adult--have been treated with liquid ventilation as part of clinical trials. However, most of the clinically relevant information known to the medical field about liquid ventilation still comes from the laboratory. This paper seeks to briefly present current information available from studies involving liquid ventilation, both laboratory-based and clinical trials, as well as to inform the reader on patient management. In addition, we attempt to elucidate future directions.
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Pregnancy imposes a load on the respiratory system that is usually easily assumed because of alterations in the thoracoabdominal architecture. It is presumed that the respiratory mechanical disadvantage of severe kyphoscoliosis and the muscle weakness of spinal muscular atrophy impede these adaptations sufficiently to preclude a successful gestation. We report the case of a successful pregnancy in a woman with spinal muscular atrophy, severe uncorrected scoliosis, and the lowest spirometric values reported in the literature without the use of ventilatory support. This patient demonstrates that women with severe kyphoscoliosis and a profound ventilatory limitation can carry a successful pregnancy well into the third trimester without requiring full ventilatory support.
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AIM: The aim of this paper is to illuminate meanings of becoming dependent on home mechanical ventilator treatment. BACKGROUND: People suffering from chronic alveolar hypoventilation and requiring home mechanical ventilation represent a small but increasing group in society, and are some of the most vulnerable individuals with chronic disabilities. METHOD: Thirteen people about to begin ventilator treatment at home were interviewed. Data were tape-recorded and analysed according to a phenomenological-hermeneutic method. FINDINGS: Findings revealed two contrasting meanings of being in the process of becoming dependent on a ventilator, interpreted as getting breath or holding breath. This interpretation is presented in two composite stories. CONCLUSIONS: The findings imply possibilities and deficiencies in meeting patients' existential needs, such as helping them to breathe spiritually by supporting them as they get their breath after such a life-changing event as becoming dependent on a ventilator.
The original rationale for HFPPV was that under certain conditions adequate alveolar ventilation could be achieved with high ventilatory frequencies and small tidal volumes. It was theorized further that increased ventilatory frequencies and low tidal volumes would decrease the airway pressures, barotrauma, and cardiovascular and other systemic consequences seen with conventional mechanical ventilation. The first clinical applications of HFPPV were in bronchoscopy and laryngoscopy for diagnostic and/or therapeutic purposes. Apart from these endoscopic applications, volume-controlled HFPPV has been compared with conventional ventilation in upper abdominal surgery and coronary artery bypass grafting. The possible advantages of HFPPV over conventional volume-controlled ventilation in the intensive care setting are still unclear. Provided that the mean lung volumes are similar, oxygenation in acute respiratory failure is similar with both ventilation methods. Although the role of HFPPV in the management of pulmonary diseases still remains to be clarified, it does provide effective ventilation in selected types of patients needing ventilatory support. New modes of pressure-controlled ventilation have not resolved all clinical problems in severe ARDS and/or acute respiratory failure. The search for means of optimal ventilatory support with minimal complications must continue, as conventional ventilation does not always offer the best treatment.
Achondroplasia can result in respiratory difficulty in early infancy, from anatomical abnormalities such as mid-facial hypoplasia and/or adenotonsillar hypertrophy, leading to obstructive apnea, or to pathophysiological changes occurring in nasopharyngeal or glossal muscle tone, related to neurological abnormalities (foramen magnum and/or hypoglossal canal problems, hydrocephalus), leading to central apnea. More often, the two respiratory components (central and obstructive) are both evident in mixed apnea. Polysomnographic recording should be used during preoperative and postoperative assessment of achondroplastic children and in the subsequent follow-up to assess the adequacy of continuing home respiratory support, including supplemental oxygen, bilevel positive airway pressure, or assisted ventilation.
Medical problems occurring during electroconvulsive therapy were studied in a population of 293 psychiatric inpatients who received 2,809 treatments. Geriatric patients (N = 199) developed significantly more medical problems that required medical treatment or temporary discontinuation of electroconvulsive therapy than did younger controls (N = 94). The most important of these were cardiovascular in nature. Despite their increased frequency, the majority of medical problems that occurred were reversible. Electroconvulsive therapy therefore appeared to be a safe procedure for elderly psychiatric patients.
OBJECTIVE: To examine the cardiovascular and respiratory health of people with severe mental illness (SMI) and compare findings with the Health Surveys for England. METHOD: A prospective, multi-centre observational prevalence study of 602 patients with schizophrenia-related psychoses carried out in six locations across the UK over 24 months. RESULTS: Compared with general population subjects, people with SMI reported higher rates of angina and respiratory symptoms and had poor lung function. Much of this increased risk could be explained by lifestyle risk factors; there were increased levels of obesity among younger people with SMI. CONCLUSION: Key indicators of the cardiovascular and respiratory health of people with SMI are poor compared with those of the general population. Care plans should prioritize interventions to attenuate lifestyle risk factors. Evidence of increasing obesity in younger patients is of particular concern, predicting even greater health needs in the future.
Nine preterm newborn infants were maintained on conventional mechanical ventilation for respiratory diseases were given high frequency jet ventilation in the same inspired FiO2 for short periods (10-120 min). Lower mean airway pressures were used in high frequency jet ventilation (0.70 +/- 0.2 kPa versus 0.96 +/- 0.2 kPa in intermittent positive pressure ventilation), and peak inspiratory pressures were reduced from 2.06 +/- 0.4 to 1.38 +/- 0.24 kPa. Respiratory and haemodynamic data were compared with those obtained in intermittent positive pressure ventilation, PaO2 and PCO2 were similar, while an increase in pH and reduction of central venous pressure were observed during high frequency jet ventilation. This preliminary study indicates that high frequency jet ventilation provides good ventilatory support, at least for short periods, with reduced airway pressures, and could be a promising technique for prevention of acute and chronic pulmonary barotrauma.
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BACKGROUND: The long term outcome of children entered into neonatal trials of high frequency oscillatory ventilation (HFOV) or conventional ventilation (CV) has been rarely studied. OBJECTIVE: To evaluate respiratory and neurodevelopmental outcomes for children entered into the United Kingdom Oscillation Study, which was designed to evaluate these outcomes. METHODS: Surviving infants were followed until 2 years of age corrected for prematurity. Study forms were completed by local paediatricians at routine assessments, and parents were asked to complete a validated neurodevelopmental questionnaire. RESULTS: Paediatricians' forms were returned for 73% of the 585 surviving infants. Respiratory symptoms were common in all infants, and 41% had received inhaled medication. Mode of ventilation had no effect on frequency of any symptoms. At 24 months of age, severe neurodevelopmental disability was present in 9% and other disabilities in 38% of children, but the prevalence of disability was similar in children who received HFOV or CV (relative risk 0.93; 95% confidence interval 0.74 to 1.16). The prevalence of disability did not vary by gestational age, but boys were more likely to have overall disability. Developmental scores were unaffected by mode of ventilation (relative risk 1.13; 95% confidence interval 0.78 to 1.63) and were lower in infants born before 26 weeks gestation compared with babies born at 26-28 weeks. CONCLUSIONS: Initial mode of ventilation in very preterm infants has no impact on respiratory or neurodevelopmental morbidity at 2 years. HFOV and CV appear equally effective for the early treatment of respiratory distress syndrome.
Transcutaneous PO2, heart rate, and aortic blood pressure were measured i 10 mechanically-ventilated newborn infants to assess the degree and course of hypoxaemia, and to monitor the cardiovascular and respiratory changes during tracheal toilet. Five infants weighed less than 1250 (mean 994), g and 5 infants weighed greater than 1750 (mean 2216) g. During tracheal suction the TcPO2 fell from 68 +/- 27 (mean +/- SD) to 43 +/- 23 mmHg, and the heart rate from 144 +/- 8 to 123 +/- 25 beats/minute, but the blood pressure increased from 44 to +/- 24 to 49 +/- 24 mmHg. Hypoxaemia (TcPO2 less than 50 mmHg) occurred in 7 of 8 initially well-oxygenated infants when suctioned. The decrease in TcPO2 was similar for both groups of infants. It was greater in infants with controlled ventilation and an F1O2 greater than or equal to 0.8 than in infants with intermittent mandatory ventilation and an F1O2 less than 0.8. The TcPO2 fall correlated well with the TcPO2 during the control period but not during the time that the infants were disconnected from the respirator. A critical re-evaluation of routine tracheal toilet is needed.
Periventricular haemorrhage was diagnosed in vivo in 20 of 29 consecutively admitted infants of birthweight below 1500 g using an ultrasound scanner. Ten (51%) infants with haemorrhages survived. Mortality was related to the extent of the bleeding. Statistically significant associations with respiratory distress, ventilator therapy, metabolic acidosis, and hypercapnia were observed, lending support to their role in the pathogenesis of periventricular haemorrhage.
The clinical features of 14 neonates with congenital myotonic dystrophy were retrospectively reviewed. These babies represent all the new cases of congenital myotonic dystrophy seen in this department since 1982. Twelve babies were referred because of either difficulties in diagnosis or difficulties in the management of their respiratory problems. Of the 14 babies, 13 had birth asphyxia, 11 were premature, and four had intrauterine growth retardation. Ten babies required artificial ventilation from birth. Abnormalities on chest radiography included thin ribs (n =9) and raised right hemidiaphragms (n = 5). Recurrent episodes of collapse and consolidation of the lungs secondary to poor swallowing occurred in all ventilated babies. All babies ventilated for longer than four weeks died of respiratory complications before the age of 15 months. One baby was successfully extubated after diaphragmatic plication, but he died a few months later. Duration of ventilation was the best guide to prognosis.