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Respiratory infections in infants on mechanical ventilation: the immune response as a diagnostic aid.

A prospective study was undertaken in 41 newborn infants receiving artificial respiration for evaluation of the incidence of respiratory infections. Clinical and radiologic evidence of pneumonia was compared with the appearance of serum antibodies against antigens prepared from microorganisms isolated from bronchial aspirates, and with serum and bronchial immunoglobulin M values. A significant specific immune response was documented in 24% of the patients studied. The data indicate that by correlating the clinical and radiographic findings with specific antibodies and IgM antibody responses, it is possible to document a significant number of respiratory infections. One implication of this study is that subclinical infections may not be uncommon. The significance of the presence and changes in concentration of IgM in bronchial aspirate requires further study.

Antibodies, Bacterial↗

Protective effects of Ca++-antagonist agents on the cerebral electrical activity during anoxia in the rat.

Transient anoxia obtained in curarized rats by momentary stopping of the artificial respiration (80 sec duration) induced a failure of the cerebral electrical activity. This effect was characterized by cessation of the spontaneous unitary discharge of cortical neurons and reduction of amplitude of somatosensory evoked potentials. Pretreatment with flunarizine (10 mg/kg/os) or suloctidil (50 mg/kg/os) induced a distinct improvement of the resistance to anoxia and of the recovery of the cerebral electrical activity.

Animals↗

The locked-in syndrome : what is it like to be conscious but paralyzed and voiceless?

The locked-in syndrome (pseudocoma) describes patients who are awake and conscious but selectively deefferented, i.e., have no means of producing speech, limb or facial movements. Acute ventral pontine lesions are its most common cause. People with such brainstem lesions often remain comatose for some days or weeks, needing artificial respiration and then gradually wake up, but remaining paralyzed and voiceless, superficially resembling patients in a vegetative state or akinetic mutism. In acute locked-in syndrome (LIS), eye-coded communication and evaluation of cognitive and emotional functioning is very limited because vigilance is fluctuating and eye movements may be inconsistent, very small, and easily exhausted. It has been shown that more than half of the time it is the family and not the physician who first realized that the patient was aware. Distressingly, recent studies reported that the diagnosis of LIS on average takes over 2.5 months. In some cases it took 4-6 years before aware and sensitive patients, locked in an immobile body, were recognized as being conscious. Once a LIS patient becomes medically stable, and given appropriate medical care, life expectancy increases to several decades. Even if the chances of good motor recovery are very limited, existing eye-controlled, computer-based communication technology currently allow the patient to control his environment, use a word processor coupled to a speech synthesizer, and access the worldwide net. Healthy individuals and medical professionals sometimes assume that the quality of life of an LIS patient is so poor that it is not worth living. On the contrary, chronic LIS patients typically self-report meaningful quality of life and their demand for euthanasia is surprisingly infrequent. Biased clinicians might provide less aggressive medical treatment and influence the family in inappropriate ways. It is important to stress that only the medically stabilized, informed LIS patient is competent to consent to or refuse life-sustaining treatment. Patients suffering from LIS should not be denied the right to die - and to die with dignity - but also, and more importantly, they should not be denied the right to live - and to live with dignity and the best possible revalidation, and pain and symptom management. In our opinion, there is an urgent need for a renewed ethical and medicolegal framework for our care of locked-in patients.

Consciousness↗

Toxicokinetics of soman: species variation and stereospecificity in elimination pathways.

Blood levels of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were analyzed gas chromatographically in anaesthetized, artificially respirated and atropinized rats, guinea pigs and marmosets at intravenous doses of C(+/-)P(+/-)-soman corresponding with 1-6 LD50. The relatively nontoxic C(+/-)P(+/-)-isomers disappear within a few minutes from the blood stream of all three species, whereas the levels of the highly toxic C(+/-)P(-)-isomers remain toxicologically relevant for periods of 50-100 min in three species of doses of 2-3 LD50. Elimination pathways were quantified using 14C-labeled soman stereoisomers. Whereas the C(+/-)P(+)-isomers are largely eliminated by way of enzymatic hydrolysis, the major elimination pathway for the C(+/-)P(-)-isomers is binding to various proteins, in competition with binding to target acetylcholinesterase. Intraspecies nonlinearity with dose in the toxicokinetics of the C(+/-)P(-)-isomers is related to heterogeneous reactivity of the binding sites. Interspecies nonlinearity is probably due to decreasing amounts of binding sites in the order rats greater than guinea pigs greater than primates, leading to increasing "toxico-availability" in the reversed order.

Animals↗

Subdiaphragmatic pressure to expel water from the lungs of drowning persons.

The Schafer artificial respiration method, which compressed the lungs to expel water, was abandoned in 1958 when mouth-to-mouth ventilation became the primary resuscitation method. Water thus remained in the lungs, making mouth-to-mouth ineffectual for treating drowning. Subdiaphragmatic pressure (Heimlich Maneuver) effectively evacuates water from the lungs by elevating the diaphragm and compressing the lungs. The method is safe because it eliminates compression of the rib cage. The first step in resuscitating a drowning person should be subdiaphragmatic pressure repeated until water ceases to flow from the mouth.

Diaphragm↗

Substance P evokes bradycardia by stimulation of postganglionic cholinergic neurons.

Substance P (SP) evokes bradycardia that is mediated by cholinergic neurons in experiments with isolated guinea pig hearts. This project investigates the negative chronotropic action of SP in vivo. Guinea pigs were anesthetized with urethane, vagotomized and artificially respired. Using this model, IV injection of SP (32 nmol/kg/50 microl saline) caused a brief decrease in heart rate (-30+/-3 beats/min from a baseline of 256+/-4 beats/min, n = 27) and a long-lasting decrease in blood pressure (-28+/-2 mmHg from baseline of 51+/-5 mmHg, n = 27). The negative chronotropic response to SP was attenuated by muscarinic receptor blockade with atropine (-29 +/- 9 beats/min before vs -8 +/- 2 beats/min after treatment, P = 0.0204, n = 5) and augmented by inhibition of cholinesterases with physostigmine (-23 +/- 6 beats/min before versus -74 +/- 20 beats/min after treatment, P = 0.0250, n = 5). Ganglion blockade with chlorisondamine did not diminish the negative chronotropic response to SP. In another series of experiments, animals were anesthetized with sodium pentobarbital or urethane and studied with or without vagotomy. Neither anesthetic nor vagotomy had a significant effect on the negative chronotropic response to SP (F3,24 = 1.97, P = 0.2198). Comparison of responses to 640 nmol/kg nitroprusside and 32 nmol/kg SP demonstrated that the bradycardic effect of SP occurs independent of vasodilation. These results suggest that SP can evoke bradycardia in vivo through stimulation of postganglionic cholinergic neurons.

Anesthetics↗

Cardiovascular and anticholinergic effects of zimelidine.

1. Pentobarbital anaesthetized mongrel dogs on artificial respiration were instrumented for recording of cardiovascular parameters. 2. Zimelidine or tricyclic antidepressants (amitriptyline, clomipramine or desipramine) were given i.v. at a rate of 0.5 mg/kg/min. 3. Zimelidine caused a moderate decrease in mean arterial blood pressure and in peripheral resistance. These effects were not dose dependent. 4. The tricyclic antidepressants induced a dose dependent decrease in mean arterial blood pressure and dose dependent increases in left ventricular enddiastolic pressure and in right atrial pressure. 5. It is concluded that the tricyclics have direct effects on the heart. Zimelidine has negligible direct heart effects but decreases peripheral resistance. 6. Studies in rat brain homogenates indicated very low affinity of zimelidine to muscarinic receptors. 7. Studies in mice indicated no central or peripheral anticholinergic effects of zimelidine in contrast to the tricyclics.

Amitriptyline↗

Guidelines for severe community-acquired pneumonia in the western world.

BACKGROUND: Recently, several guidelines (ATS 1993/IDSA 1998; ERS 1998; SWAB 1998) have been issued for the initial therapy of patients with community-acquired pneumonia. In patients who fulfil the criteria for severe community-acquired pneumonia (SCAP), it was advised to start with a macrolide (active against Legionella spp. and Mycoplasma pneumoniae) in combination with an agent active against both pneumococci and Pseudomonas aeruginosa by the ATS/IDSA guidelines, while the ERS suggested starting with a second or third generation cephalosporin, in combination with either a macrolide or second generation quinolon plus or minus rifampicin. In the SWAB guidelines, no recommendations for SCAP were made. METHODS: Sixty-two cases admitted to the intensive care units of a tertiary-care university hospital with SCAP between 1992 and 1996 were studied retrospectively. The causative pathogens, clinical and laboratory characteristics of severity, antibiotic therapy and mortality were analysed. Immunocompromised patients, patients using immunosuppressive agents and patients with a malignancy were excluded. RESULTS: Indices of severe illness were widely seen and 37% developed shock while 45% required vasoactive drugs. Bilobular or multilobular abnormalities were seen in 34% of the patients. Forty-five patients (73%) required artificial respiration and 54 (87%) had an underlying disease. The overall mortality was 42%. In 41 patients (66%), a pathogen was isolated. The most frequent causes of SCAP in this study were Streptococcus pneumoniae (22 cases or 35%), Haemophilus influenzae (seven cases or 11%), Pseudomonas aeruginosa (four cases or 7%), and other Enterobacteriaceae (twice in combination with pneumococci and once with H. influenzae). Legionella pneumophila was identified in three cases. In patients with severe chronic obstructive pulmonary disease (COPD), pneumococci were the most important pathogens six cases or 27%), followed by P. aeruginosa (14%) and H. influenzae (14%). CONCLUSIONS: The guidelines for the management of SCAP issued by the ATS and IDSA in 1993 are only partially adequate in the Dutch setting. Coverage of P. aeruginosa would seem useful, given the fact that isolation of this pathogen has been shown to be a predictor of mortality, but only in patients with severe COPD or structural disease of the lung, and especially in patients in whom the Gram stain reveals Gram-negative rods, as is also suggested in the revised IDSA guidelines (1998). Risk factors for P. aeruginosa could be added to the ERS guidelines. Including SCAP as a separate entity in the SWAB guidelines may be useful.

Adult↗

A serial muscle biopsy study in a case of congenital fiber-type disproportion associated with progressive respiratory failure.

The muscle fiber diameter and distribution were studied in serial muscle biopsy specimens taken at the ages of 21 months and 8 years in a girl with congenital fiber type disproportion. The patient was floppy from birth and showed delayed motor development. Progressive respiratory failure developed from the age of 8, which required artificial respiration during the night. The mean diameters of type 1 fibers at the ages of 21 m and 8 y were 10 mu and 21 mu, and those of type 2 fibers 32 mu and 61 mu, respectively. Whereas most type 1 fibers were hypotrophic in both biopsy specimens, a small number of type 1 fibers (approximately 15%) were normal-sized or hypertrophic, measuring 50 to 90 mu, in the second biopsy specimen, which were thought to have arisen on the maturation of normal-sized or hypertrophic type 1 fibers measuring 15 to 35 mu in the first biopsy specimen. Excessive hypotrophy of type 1 fibers was considered to be responsible for the progressive respiratory failure due to weakness of the diaphragm. The pattern of type 1 fiber evolution from the first to the second biopsy specimen suggested that dysmaturation of spinal motoneurons innervating type 1 muscle fibers would be involved in the pathophysiology of the fiber type disproportion in this case.

Child↗

[Propofol in the surgery of the aortic bifurcation. Comparison with isoflurane].

Two groups of nine patients each, all undergoing surgery for aorto-bifemoral prosthesis, were studied. They were premedicated with 10 mg morphine and 1 mg flunitrazepam. A Swan-Ganz catheter was then inserted. Cardiac output was measured by thermodilution. Haemodynamic parameters were measured before induction (t0), 15 min after intubation (t1), 10 min after the start of the surgical procedure (t2), 5 min before clamping the aorta (t3), whilst the aorta was clamped (t4), and a few minutes after unclamping. Group A received 2 mg X kg-1 propofol at induction, anaesthesia being maintained with 100 micrograms X kg-1 X min-1 propofol. Group B received 4 mg X kg-1 thiopentone, followed by isoflurane at the dose of 0.9 vol. %. Both groups received 5 micrograms X kg-1 fentanyl and 0.1 mg X kg-1 vecuronium to ease intubation. Artificial respiration was carried out with a mixture of 40% oxygen and 60% nitrous oxide. The fall in blood pressure between t2 and t3 was significantly more important in the propofol group (-16%). In the same group, the systolic blood pressure and heart rate fell by 23 and 19% respectively after induction (p less than 0.05); the cardiac index fell by 20% and the systemic vascular resistances did not change. The fall in blood pressure, heart rate and cardiac index were not significant for group B. The haemodynamic changes due to clamping of the aorta were not significant between or within groups. In group A, one patient presented with bradycardia, hypotension and myocardial ischaemia, and another died of postoperative ventricular fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Predicting coronary disease risk based on short-term RR interval measurements: a neural network approach.

Coronary heart disease is a multifactorial disease and it remains the most common cause of death in many countries. Heart rate variability has been used for non-invasive measurement of parasympathetic activity and prediction of cardiac death. Patterns of heart rate variability associated with respiratory sinus arrhythmia have recently been considered as possible indicators of coronary heart disease risk in asymptomatic subjects. The aim of this work is to detect individuals at varying risk of coronary heart disease based on short-term heart rate variability measurements under controlled respiration. Artificial neural networks are used to recognise Poincaré-plot-encoded heart rate variability patterns related to coronary heart disease risk. The results indicate a relatively coarse binary representation of Poincaré plots could be superior to an analogue encoding which, in principle, carries more information.

Coronary Disease↗

Peripheral heat as a reward for heart rate response in the curarized rat.

It is generally assumed that the mechanical perception of shivering is necessary for the perception of cold discomfort. Shivering of rats in a cool environment was eliminated by curarization. The rats were kept alive by artificial respiration. Heart rate was proportional to rectal temperature in a group of controls. One group of rats was conditioned to increase heart rate to trigger an infrared lamp; another group was conditioned to decrease heart rate to obtain heat. When compared with the results of the control group without infrared heat reward, the results obtained from the two heart-rate-modifying groups show that shivering is not a necessary signal to determine thermoregulatory behavior in rats and, presumably, cold discomfort in man.

Animals↗

Parasympathetic denervation of rat pial vessels significantly increases infarction volume following middle cerebral artery occlusion.

Studies were undertaken in Long Evans rats to examine the hypothesis that chronic unilateral sectioning of vasodilating nerve fibers (parasympathetic and/or sensory) innervating the circle of Willis increases infarction volume following unilateral branch occlusion of the middle cerebral artery (MCA) combined with temporary (45 min) bilateral common carotid occlusion. Infarct size was measured 24 h after surgical occlusion from seven coronal slices. Infarction volume (mean +/- SD) in sham animals (group A) and surgically naive animals (group B) measured 153 +/- 43 and 131 +/- 38 mm3, respectively. After lesions of both sensory (nasociliary nerve) and parasympathetic efferents at the ethmoidal foramen (group C, combined lesion) or selective lesions of parasympathetic efferents (group D), infarction volume increased [214 +/- 47 mm3 (p less than 0.01) and 209 +/- 46 mm3 (p less than 0.05), respectively]. No increases were detected after cutting the nasociliary nerve alone (group E) or occluding the external ethmoidal artery (group F) [145 +/- 39 mm3 (p greater than 0.05) and 124 +/- 63 mm3 (p greater than 0.05), respectively]. The infarct was predominantly located within cortical gray matter and became enlarged on its superior and inferior aspects after parasympathectomy. Large infarcts were noted whether animals breathed spontaneously (all of the above) or were artificially respired or whether animals were anesthetized with xylazine and ketamine or chloral hydrate. Taken together, these studies suggest a previously unrecognized protective role for autonomic parasympathetic fibers in the pathophysiology of focal cerebral ischemia that is not shared by sensory fibers. The importance of autonomic vasodilating fibers to blood flow in ischemic brain merits further study.

Animals↗

Peculiar septic responses in traumatic tetraplegic patients.

Patients with a high level tetraplegia from a spinal injury have only been able to survive the critical initial period since the development of modern resuscitation techniques including artificial respiration. However, their lives are still threatened by many complications, such as decubitis ulcers, infections and respiratory failure. We describe four young tetraplegic patients who developed an unusual sepsis pattern several years after the injury. The sepsis was accompanied by hypothermia, leukopenia and mental deterioration. This peculiar 'silent' sepsis may also occur in elderly people who are not paralysed. The question arises, therefore, if the chronic spinal cord injured patient may become 'prematurely aged'.

Adult↗

Canine external carotid vasoconstriction to methysergide, ergotamine and dihydroergotamine: role of 5-HT1B/1D receptors and alpha2-adrenoceptors.

The antimigraine drugs methysergide, ergotamine and dihydroergotamine (DHE) produce selective vasoconstriction in the external carotid bed of vagosympathectomized dogs anaesthetized with pentobarbital and artificially respired, but the receptors involved have not yet been completely characterized. Since the above drugs display affinity for several binding sites, including alpha-adrenoceptors and several 5-HT1 and 5-HT2 receptor subtypes, this study has analysed the mechanisms involved in the above responses. Intracarotid (i.c.) infusions during 1 min of methysergide (31-310 microg min(-1)), ergotamine (0.56-5.6 microg min(-1)) or DHE (5.6-31 microg min(-1)) dose-dependently reduced external carotid blood flow (ECBF) by up to 46+/-4, 37+/-4 and 49+/-5%, respectively. Blood pressure and heart rate remained unchanged. The reductions in ECBF by methysergide were abolished and even reversed to increases in animals pre-treated with GR127935 (10 microg kg(-1), i.v.). The reductions in ECBF by ergotamine and DHE remained unchanged in animals pre-treated (i.v.) with prazosin (300 microg kg(-1)), but were partly antagonized in animals pre-treated with either GR127935 (10 or 30 microg kg(-1)) or yohimbine (1000 microg kg(-1)). Pre-treatment with a combination of GR127935 (30 microg kg(-1)) and yohimbine (1000 microg kg(-1)) abolished the responses to both ergotamine and DHE. The above doses of antagonists were shown to produce selective antagonism at their respective receptors. These results suggest that the external carotid vasoconstrictor responses to methysergide primarily involve 5-HT1B/1D receptors, whereas those to ergotamine and DHE are mediated by 5-HT1B/1D receptors as well as alpha2-adrenoceptors.

Adrenergic alpha-1 Receptor Antagonists↗

Dysphagia in patients with acute cervical spinal cord injury.

STUDY DESIGN: Longitudinal observational. OBJECTIVES: (a) To establish a reliable and feasible method to indicate the presence and severity of dysphagia and (b) to establish a course of treatment in individuals presenting with cervical spinal cord injury (CSCI). SETTING: Spinal Cord Injury Center, Werner Wicker Klinik, Bad Wildungen, Germany. PATIENTS AND METHODS: This is a cross-sectional study of 51 patients consecutively admitted to the Intensive Care Unit of the SCI in-patient service. They were subjected to neurological and fiberoptic endoscopic examination of swallowing (FEES). Data concerning artificial respiration, presence of tracheostomy, oral or non-oral feeding were obtained from the medical charts. Statistics were carried out by a calculation of a nonparametric correlation (Spearman). RESULTS: Five levels of dysphagia could be distinguished. At levels 1 and 2, patients presented with a severe impairment of swallowing, in level 3 aspiration was met by a powerful coughing reflex, level 4 comprised a laryngeal edema and/or a mild aspiration of fluids only and at level 5 laryngeal function was not compromised. On admission, 20 patients with CSCI presented with mild (level 4), eight with moderate (level 3) and 13 with severe dysphagia (levels 1 and 2). In 10 no signs of dysphagia could be detected. After treatment, level 1 was no longer detected, one patient showed level 2, two patients showed level 3, all other patients showed only mild or no signs of dysphagia any longer. CONCLUSIONS: Dysphagia of various severities was present in the majority of these patients with CSCI together with respiratory insufficiency. FEES allows for the detection and classification of dysphagia as well as for an evaluation of the therapeutic management. Under interdisciplinary treatment the prognosis of dysphagia is good.

Adolescent↗