Reversal potential for noradrenaline-induced hyperpolarization of spinal motoneurons.

By using two separate electrodes with tips inside a single feline motoneuron, current-voltage characteristics were studied during extracellular iontophoresis of noradrenaline. The usually observed hyperpolarization was accompanied by an increase in membrane resistance and became larger with polarizing and smaller with depolarizing currents. During large depolarizing current injections, the noradrenaline-induced potential reversed its direction, usually at a membrane potential of about -20 millivolts. These data are compatible with the concept that noradrenaline hyperpolarizes nerve cells by decreasing resting membrane conductances to sodium and potassium ions. The observation could also be explained by a nonspecific decrease in ion permeability that is associated with a hyperpolarization due to sodium pump activation.

The response of cat spinal motoneurones to the intracellular application of agents with local anaesthetic action.

QX-222 (the trimethyl analogue of lignocaine), methylxylocholine, lignocaine and pentobarbitone were iontophoresed intracellularly into cat lumbosacral motoneurones. Iontophoresis and recording was either from a triple-barrelled microelectrode unit or from two separately advanced microelectrodes. QX-222 and methylxylocholine caused a very slow reversible block of the current-evoked and antidromic action potentials (AP) with no significant change of membrane potential (EM). Lignocaine had a minimal blocking effect on the AP. No change, or only a small decrease, of membrane slope conductance (GM) was seen when the APs had been totally abolished. QX-222 and methylxylocholine reduced the massive GM increase evoked by the passage of large depolarizing currents and converted the post-current hyperpolarization (time constant 120-150 ms) into a depolarization of similar time course. It is suggested that the quaternary local anaesthetics can reduce the fast and slow voltage-dependent potassium conductances. Both agents totally blocked AP generation without decreasing the magnitude of the Ia e.p.s.p. It is suggested that intracellularly iontophoresed QX-222 (on account of its low lipid solubility) could be used as a pharmacological tool to block specifically the active Na and channels in only the cell impaled by the microelectrodes.

Excitation of substantia nigra pars compacta neurones by 5-hydroxy-tryptamine in-vitro.

Incoming serotonergic fibres are known to make direct synaptic contact with dopamine-containing neurones in the substantia nigra pars compacta (SNc). However, the effects of 5-HT (5-hydroxytryptamine) on these cells have not been thoroughly investigated. In the present study we show that application of 10-50 microM 5-HT increases the firing frequency of SNc neurones in-vitro, and produces inward rectification in a voltage region negative to -50mV. This effect is sensitive to extracellular Cs+, but not to Ba2+, and has similar properties as the intrinsic inward rectifier current, Ih. Antagonists of the 5-HT1A and 5-HT2 receptors were inefficacious. It is concluded that 5-HT excites SNc neurones via an enhancement of the conductance underlying Ih.

A comparison of extracellular and intracellular recording during extracellular microiontophoresis.

A technique is described in which a central recording microelectrode can be moved independently of a concentrically arranged multibarrelled electrode prepared for microiontophoresis. Recordings were made from cat spinal motoneurones during microiontophoretic applications of excitatory amino acids and biogenic amines with the central electrode placed first extracellularly and then intracellularly. Recording were also made from one of the iontophoretic barrels. Both intra- and extracellular electrodes were used to record action potential firing, the ventral root field (VRF) evoked by antidromic ventral root stimulation and the membrane potential (EM). They were also used to record 'focal potentials' evoked by the extracellular application of drugs to nearby neurones. The firing pattern evoked by extracellular iontophoretic applications of DL-homocysteate and glutamate was not altered significantly following impalement of the cell by the recording microelectrode. Excitatory amino acids usually caused a reduction of the VRF negative wave and evoked an additional late positive wave. These VRF changes recovered at the same rate as the extracellularly recorded, negative 'focal potentials' (Flatman and Lambert, 1979). Iontophoretic applications of biogenic amines caused small increases, small decreases, or no change of the VRF negative wave. Variable responses were also seen during intracellular recording: hyperpolarization, no response and, occasionally, depolarizations were recorded. It is concluded that, during the drug action, VRF changes are difficult to interpret and are a poor index of drug-evoked changes in neuronal excitability or EM.

L-glutamate and N-methyl-D-asparatate actions on membrane potential and conductance of cat abducens motoneurones.

The actions of L-glutamate and N-methyl-D-aspartate (NMDA) were studied with intracellular recordings from cat abducens motoneurones. Amino acids were electrophoresed extracellularly from the same 7-barreled electrode types as those used in the spinal cord. Depolarization development, conductance changes and firing pattern induced by amino acids were very similar to those described for spinal motoneurones. The shape of NMDA depolarization suggests a uniform distribution of the involved receptors on the membrane of the motoneurone.

A comparison of the incidence of breast feeding two and four months after delivery in mothers discharged within 72 hours and after 72 hours post delivery.

OBJECTIVE: To compare breast feeding at two and four months after delivery in mothers discharged early (ED = before 72 hours post delivery) and late (LD = after 72 hours post delivery), and to explore the factors of greatest importance to the successful practice of breast feeding. DESIGN: Ex-post facto design. SETTING: In the country of Härryda, Sweden. PARTICIPANTS: All Swedish speaking women in the country of Härryda whose babies were born between 01.01.94 and 31.05.94 and who were registered at the Child Health Station (CHS) by the age of three months. One hundred and ninety women were invited to participate and 157 (83%) accepted. MEASUREMENTS AND FINDINGS: No significant difference was found in the breast feeding rates between the ED and LD group. However, ED mothers breast fed exclusively to a higher extent at two and at four months (exclusive breast feeding: at two months 89% and 86% respectively, and at four months 84% and 74% respectively, partial breast feeding: at two months 6% and 10% respectively, and at four months 5% and 12% respectively). If the woman considered that she had received encouragement and support while breast feeding for the first time, the probability of her breast feeding at two and at four months were about six times as great (Exp(B) 5.7594, df = 1, p = 0.0270; (Exp(B) 5.9781 df = 1, p = 0.0005 respectively). KEY CONCLUSIONS: The length of the hospital stay had no significant effect on the incidence of breast feeding at two and four months post delivery. The most predominant factors influencing breast feeding were seen to be the mother's first experience of breast feeding and the degree of support, help and encouragement she received. Less than half of the women received a visit from the CHS nurse after their return home from hospital. IMPLICATIONS FOR PRACTICE: The findings suggest that it is important that the midwife or nurse should prepare, support and encourage the mother when breast feeding for the first time. The midwife's or nurse's interventions are important for the incidence of breast feeding, at least during the first four months, and indirectly affect public health. This must also be taken into consideration when caring for mothers in the delivery ward and before discharge, i.e. that the breast feeding is working well, that the mother experiences it as working well, and also for planning follow-up after discharge.

Prevalence of skin and genital mucous membrane irritations in patients confined to bed.

A comparative and prospective study of the skin and genital mucous membrane conditions of 50 intensive care patients, who were entirely confined to bed, was conducted. Skin and/or genital mucous membrane irritations were developed by 31 patients during their stay in the ICU. These patients had a significantly longer stay in bed in the ICU than those who did not develop such changes. Patients with lesions were significantly washed more often using the pH 8.5 soap than those without lesions. Erythematous was the most commonly observed symptom and the area between the buttocks and saccrum was the most affected.

Intensive care syndrome: a literature review.

The aim in this literature review is to describe the definitions, denominations, clinical signs and symptoms, explanations, causative factors and interrelationships of the intensive care syndrome discussed since 1950. It was found that there is no agreement about which symptoms should be included in the syndrome, when the syndrome may appear and how many patients may be affected. Furthermore, it is unclear what causes the development of the syndrome; most authors conclude that there are many reasons for it. The syndrome has generally been examined by using a medical or psychological approach, but during the last few years it has also been described and analysed from a nursing care perspective. From this nursing perspective the syndrome may be seen as an individual pattern developed by patients during their stay in an intensive care unit (ICU) and sometimes this pattern of clinical signs and symptoms lasts for a shorter or longer period even after discharge from the unit. From a wider viewpoint the development of the syndrome can be seen as an increase by degrees or as a vicious circle. finally, most authors agree that the ICU syndrome consists of, and is caused by, a complex interaction between many factors.

Patients' experience of being critically ill or severely injured and cared for in an intensive care unit in relation to the ICU syndrome. Part I.

The intensive care unit (ICU) syndrome is regarded principally as a complex interaction of several contributory factors, all of which can be seen as partly responsible for the development of the syndrome. The purpose of this study was to describe and give a deeper insight into patients' experiences and memory recall, both during and after their stay in the ICU. Nineteen patients who had been respirator treated (ventilated), and had stayed at least 36 hours in the ICU, were interviewed about one week after discharge, and again 4-8 weeks after their discharge from the ICU. Patients' experiences are interpreted and related to previous views held concerning the syndrome, together with an awareness of other important and significant phenomena, i.e. a hermeneutic approach. This study partly confirms the findings of earlier studies concerning the ICU syndrome, but also reveals some new aspects, which have not previously been considered. The patients described themselves as experiencing some sort of state of chaos following the onset of their sickness, injury or accident, which resulted in feelings of extreme instability, vulnerability and fear, often experienced as prolonged inner tension. It was reported that even the most trivial events in circumstances or routines could trigger changes-either an increase or decrease-in patients' feelings of fear or inner tension. The caring relationship was perceived as providing an important degree of security and comfort. Nursing care actions can therefore be seen as vital factors in patients overcoming the accompanying horrific experiences to which they can be subjected. This state of chaotic feeling, and how it is combated and treated, appear to be one critical factor in the development and progression of the ICU syndrome.

Acute confusion and unreal experiences in intensive care patients in relation to the ICU syndrome. Part II.

The intensive care unit syndrome (ICU syndrome) is defined as an altered emotional state occurring in a highly stressful environment, which may manifest itself in various forms such as delirium, confusion, crazy dreams or unreal experiences. The purpose of this part of a study of patients' experiences is to describe and illuminate patients' experiences of acute confusion, disorientation, wakefulness, dreams and nightmares during and after their stay in the ICU. The data were obtained from 19 ventilated patients, who were interviewed twice and had stayed at least 36 hours in the ICU, the first interview being about one week after discharge from the ICU, and the second 4-8 weeks later. The hermeneutic approach used when interpreting and analysing the text from the interviews revealed that patients' experiences of unreal experiences were often associated with intense fear. Intense or continuous unbearable fear seems to result in frightening unreal experiences, which further increase the level of fear. Care actions or caring relationships with relatives or nurses can reduce this fear, which can help to prevent the occurrence and/or duration and intensity of the unreal experiences. Trust and confidence in nurses or significant others and feelings of self-control or trust in self-control seemed to reduce the risk of unreal experiences so that adverse stimuli might only trigger a mild confusion.

An interview study of nurses' assessment and priority of post surgical pain experience.

Caring for patients in postoperative pain is an important part of clinical practice for nurses. Patients often fail to receive adequate pain relief which causes unnecessary pain experience. The aim of this study was to describe how nurses experience their clinical practice management with postoperative patients who experience pain. Eight nurses, practising in the postoperative care unit and surgical wards were interviewed. Data were gathered in unstructured interviews and analysed by means of a qualitative method. Six categories emerged: organising condition, perspective, attitude, knowledge, experience and assessment/priority. All the conditions are interrelated and influenced the nurses' handling of pain management in nursing practice. It appeared that these conditions reflected the nurses' possibilities of relieving patients' postoperative pain. An important element was the reflection of hospital management policy which makes the nurses, in spite of their desire to relieve the patients' pain, choose to have the attitude that the patient should be prepared to accept a little pain.

The communication process with ventilator patients in the ICU as perceived by the nursing staff.

Intensive care unit (ICU) nurses (n = 27) were interviewed about their experiences and opinions of the communication process with ventilator treated patients. Nurses with limited ICU experience considered the initial contact with a new critically ill ventilated patient more frustrating than experienced nurses. The nurses thought that the content of the communication commonly requested by a patient was dominated by factors related to the clinical condition, prognosis and reassurance that the situation was under control. Factors considered to limit the communication and to create feelings of uncertainty and stress for nurses with an ICU experience of less than 5 years were: work overload, unstable condition of the patient, impaired communication with the patient, and their own personal problems or worries. For nurses with an ICU experience of more than 5 years stress was more commonly evoked by the presence of worried and anxious spouses/relatives, and by the feeling that something was wrong with the patient but they were unable to identify the problem. Failure to understand a ventilated patient could induce feelings of incompetence, stress and sometimes even despair. The present small scale study shows that there are many factors, in addition to ICU experience, that may influence the ability of an ICU nurse to establish and maintain a well functioning communication with ventilated patients and the likelihood of doing so.

Brain death in ICUs and associated nursing care challenges concerning patients and families.

In order to document the incidence and causes of brain death (BD) and the frequency of organ donation (OD) in a Swedish University Hospital, a retrospective review of deaths in a neurosurgical department and in the general intensive care units (ICUs), was carried out for the period 1988-1994. BD diagnosis was established in 197 (10.6%) of all deaths (n = 1843). The hospital records of all BD patients were examined in detail following a specific study plan. The majority of the BD patients (89%) were acute admissions to hospital, and among them 81 were transferred between hospitals often over a long distance. Among the BD patients the total number of OD was 65 (33%). The most common diagnosis leading to BD was spontaneous intracerebral bleeding and traumatic head injury. The BD diagnosis was established by neurological examination (60%) and by cerebral angiography (40%). Of the BD patients, 50% died within 48 hours in the ICU and the majority of requests for OD (67%) were made to the relatives of these patients. The findings are discussed with focus on the workload and psychological stress of ICU nurses when caring for BD patients and their families; a task which includes taking part in processes concerning BD diagnosis information and OD requests.

Evaluating nurses' knowledge and patients energy intake after intervention.

The aims of this study were to describe and assess nutritionally at-risk patients' energy intake and nurses' knowledge and opinions of patients' need of energy during their hospital stay, before and after training and education. The effects of the intervention were evaluated by using a questionnaire, answered by the nurses before and after the intervention, and indirectly by measuring the patients' nutritional outcome, using a nutritional assessment form. A total of 230 matched patients and 171 nurses (86 before the intervention and 85 after) participated in the study. After the education, results indicated that a greater number of patients received increased levels of energy intake, an increased average intake of energy, and more dietary supplements. Nurses' knowledge about the content of energy in a standard portion of food had increased, and they found it easier to assess patients' need of energy. After the education, more nurses had the opinion that well-educated nurses in nutrition make it easier to motivate patients to reach a sufficient intake of energy.