An unusual presentation of congenital central hypoventilation syndrome (Ondine's Curse).

Congenital central hypoventilation syndrome is a rare illness, which classically presents in the neonatal period; newborns present with shallow breathing and cyanosis, without a physiological rise in breathing rate. Incidence has been estimated from 1 in 10,000 to 1 in 200,000 live births. This case report describes the case of a young man who was asymptomatic until his presentation in acute respiratory failure at the age of 36 years. This case is reported to highlight the importance of considering this treatable illness as a potential cause of collapse and respiratory failure in adults presenting to emergency departments.

Effect of awake Carotid Endarterectomy under local anaesthesia on peri-operative blood pressure: blood pressure is normalised when carotid stenosis is treated under local anaesthesia.

BACKGROUND: Carotid Endarterectomy can be performed under local, regional or general anaesthesia. One of the most important effects of the type of anaesthetic used is on the systemic blood pressure. Although variations in blood pressure during and following carotid endarterectomy have been studied previously, the effects of awake carotid endarterectomy under local anaesthesia on blood pressure and its comparison with similar procedures under similar types of anaesthesia have not. METHODS: Peri-operative blood pressure measurements were collected from the records of 25 consecutive patients for each of the following five procedures; Carotid Endarterectomy under general anaesthesia (CEAGA), Anterior Cervical Discectomy and Fusion under general anaesthesia (ACDF), Cerebral Angiography under local anaesthesia (ANG), Carotid Endarterectomy patients under local anaesthesia who were symptomatic (CEALAS) and Carotid Endarterectomy patients under local anaesthesia who were asymptomatic (CEALAA). The recordings were then analysed to find out if there were any clinically significant variations in peri-operative blood pressure. FINDINGS: There is a significant and consistent difference when the pre-operative value was compared with the 4 hour and 24 hour post-operative recordings between the local and general anaesthetic groups for carotid endarterectomy. Carotid endarterectomy reduces the systolic and diastolic blood pressures post-operatively when performed under local anaesthesia and only the diastolic pressure was reduced when performed under general anaesthesia. CONCLUSION: The study provides evidence about the effect of carotid endarterectomy on the systemic blood pressure and its variations when performed under different types of anaesthesia. There is significant post-operative reduction in both the systolic and diastolic blood pressure values and the intraoperative fluctuation is minimal when local anaesthesia is used. Further studies are required to find out how this affects the long-term blood pressure and clinical outcome of the patient.

Bispectral index monitoring may not reliably indicate cerebral ischaemia during awake carotid endarterectomy.

BACKGROUND: Intraoperative ischaemia during carotid cross-clamping in patients undergoing carotid endarterectomy (CEA) is a major complication and prompt recognition of insufficient collateral blood supply is crucial. Electroencephalogram (EEG) is believed to be one of the useful forms of monitoring cerebrovascular insufficiency during CEA. The aim of this study was to evaluate the utility of bispectral index (BIS) monitoring, a processed EEG parameter, for the reliable detection of intraoperative cerebral ischaemia during awake CEA. METHODS: We monitored 52 patients continuously with the BIS monitor together with assessment of neurological function (contralateral upper and lower limb strength and the verbal component of the Glasgow Coma Scale for speech) in patients undergoing awake CEA. RESULTS: Overall mean BIS value in all patients was 96 (SD 2.9). In five patients who showed clinical evidence of cortical ischaemia during carotid cross-clamping, there was no change in the original range of BIS values throughout the procedure (96.7 [3.2]). In one patient BIS values decreased to 38 about 5 min after the incision and recovered within the next 10 min. The mean BIS value in the remaining 46 patients who did not develop clinical signs of ischaemia was 95.4 (2.6). Three cases are presented which demonstrate the inability of the BIS monitor to detect cerebral ischaemia. CONCLUSIONS: Lack of correlation of BIS with the signs of cerebral ischaemia during CEA makes it unreliable for detection of cerebrovascular insufficiency. We conclude that awake neurological testing is the preferred method of monitoring in these patients.

Noninvasive ventilation in ALS: indications and effect on quality of life.

BACKGROUND: Noninvasive ventilation (NIV) probably improves survival in ALS, but the magnitude and duration of any improvement in quality of life (QoL) and the optimal criteria for initiating treatment are unclear. METHODS: QoL (Short Form-36 [SF-36], Chronic Respiratory Disease Questionnaire, Sleep Apnea Quality of Life Index) and respiratory function were assessed every 2 months and polysomnography every 4 months in 22 subjects with ALS. A trial of NIV was offered when subjects met one or more predefined criteria: orthopnea, daytime sleepiness, unrefreshing sleep, daytime hypercapnia, nocturnal desaturation, or an apnea-hypopnea index (AHI) of >10. Seventeen subjects were offered a trial of NIV; 15 accepted, and 10 continued treatment subsequently. Outcome was assessed by changes in QoL and NIV compliance (h/day). Subjects were followed to death or for at least 26 months. RESULTS: QoL domains assessing sleep-related problems and mental health improved (effect sizes 0.88 to 1.77, p < 0.05) and were maintained for 252 to 458 days. Median survival following successful initiation of NIV was 512 days, and survival and duration of QoL benefit were strongly related to NIV compliance. Vital capacity declined more slowly following initiation of NIV. Orthopnea was the best predictor of benefit from, and compliance with, NIV. Daytime hypercapnia and nocturnal desaturation also predicted benefit but were less sensitive. Sleep-related symptoms were less specific, and AHI > 10 was unhelpful. Moderate or severe bulbar weakness was associated with lower compliance and less improvement in QoL. CONCLUSIONS: NIV use was associated with improved QoL and survival. Subjects with orthopnea and preserved bulbar function showed the largest benefit.

Non-invasive ventilation in motor neuron disease: current UK practice.

OBJECTIVE: To evaluate the clinical application of non-invasive ventilation (NIV) in motor neuron disease (MND) in the UK. METHOD: We conducted a postal survey of the current clinical practice of all consultant neurologists in the UK, with a second mailing to non-responders after 6 weeks. The principal outcome measures assessed were: 1. the percentage of patients with MND receiving NIV, 2. access to a NIV service, 3. routine monitoring of respiratory function, and 4. influence of symptoms, respiratory function, rate of disease progression, level of disability and bulbar involvement on referral for NIV. RESULTS: The response rate was 76%, 1719 new patients had been diagnosed in the preceding 12 months and a total of 2280 patients were under review. Of these, 126 were currently receiving NIV (5.5% of patients under review, estimated 2.6-3.5% of all MND patients). Most neurologists (172/265) had referred no patients for NIV in the preceding year, while three neurologists made 30% of all referrals nationally. Referral was based primarily on symptoms, and was influenced by the number of MND patients under review, level of disability, rate of disease progression and availability of a NIV service. Bulbar involvement was considered a relative contra-indication to NIV by 51% of responders. CONCLUSIONS: In the UK, few patients with MND are treated with NIV. There is marked variation in clinical practice. This may reflect uncertainty about the role of non-invasive ventilation in MND, and emphasizes the need for a randomized controlled trial to assess the impact of NIV on quality of life and survival.

Sleep-related breathing disorders following discharge from intensive care.

OBJECTIVES: To determine the incidence of sleep-related breathing disorders and nocturnal hypoxaemia in patients discharged from ICU following prolonged mechanical ventilation. DESIGN: Prospective, consecutive patient observational study. SETTING: The medical and surgical wards of a University Hospital. PATIENTS AND PARTICIPANTS: Fifteen consecutive, adult patients discharged from the ICU who had received more than 48 h of mechanical ventilation were studied. Ten healthy volunteers acted as controls. MEASUREMENTS AND RESULTS: Overnight, multi-channel pneumographic studies were performed on all patients and controls. Chest and abdominal wall movement, air flow, oxygen saturation and snoring were continuously recorded. Data was analysed by both visual inspection of the traces and by computer-based algorithms. An apnoea/hypopnoea index was calculated for each patient and volunteer. Volunteers had an apnoea/hypopnoea index of less than 5 and had no episodes of nocturnal oxygen desaturation (SaO2 < 90%). Despite oxygen therapy 13/15 patients had episodes of desaturation and 9/15 spent more than 2 h with an SaO2 < 90%. Eleven patients had an abnormal apnoea/hypopnoea index (range 5-34 events/h). Four patients had predominantly obstructive events while 7 primarily had hypopnoeas. CONCLUSIONS: Significant overnight oxygen desaturation is common in patients discharged from ICU who have received prolonged mechanical ventilation. This group also has a significant incidence of sleep-related breathing disorders and this mechanism is likely to be important in the pathogenesis of the hypoxaemia.

Multicore myopathy: respiratory failure and paraspinal muscle contractures are important complications.

Three ambulant males with multicore myopathy, a rare congenital myopathy, are reported with nocturnal hypoventilation progressing to respiratory failure at the age of 9, 13, and 21 years. Deterioration in these individuals occurred over several months without any precipitating event. Patients had clinical evidence of nocturnal hypoventilation with hypoxaemia and hypercapnia. Forced vital capacity was significantly reduced (20 to 43% of predicted level). These parameters improved on institution of overnight ventilation using a BiPAP pressure support ventilator with face mask or nasal pillows with O2 saturation maintained above 90% overnight and an increase in forced vital capacity by as much as 100% (0.3 to 0.6 litres). This was matched by a symptomatic and functional improvement. Also present in these patients and not previously reported is the association of multicore myopathy with paraspinal contractures which produce a characteristic scoliosis described as a 'side-sliding' spine. This may be improved by spinal bracing or surgery.

Changes in cerebral oxygen consumption are independent of changes in body oxygen consumption after severe head injury in childhood.

This study examines the relation between cerebral O2 consumption (CMRO2) and the O2 consumption of the rest of the body (BVO2) after severe head injury. Seventy nine serial measurements of whole body O2 consumption, CMRO2, plasma adrenaline, T3, and glucagon concentrations were made in 15 children with severe head injuries receiving neurointensive care. Body O2 consumption was measured with indirect calorimetry and CMRO2 with the Kety-Schmidt technique. There was no evidence of a significant relation between CMRO2 and BVO2. Within each child there were statistically significant positive relations between BVO2 and adrenaline, T3, and glucagon. By contrast, there was only a weak significant positive relation between CMRO2 and T3. In conclusion, CMRO2 and BVO2 seem to be determined independently after severe head injury. Thus therapeutic measures aiming to reduce CMRO2 need to be specific to the brain and it should not be assumed that measures which decrease whole body energy expenditure will necessarily have the same effect on CMRO2.

Temperature response to severe head injury and the effect on body energy expenditure and cerebral oxygen consumption.

This study examines the relationship between core temperature and whole body energy expenditure, cerebral oxygen consumption (CMRO2), cerebral blood flow (CBF), and intracranial pressure (ICP) in severely head injured children. A total of 107 serial measurements of temperature, energy expenditure, CMRO2, CBF, and ICP were made in 18 head injured children receiving neurointensive care. Energy expenditure was measured using indirect calorimetry, and CMRO2 and CBF using the Kety-Schmidt technique. The mean rectal temperature was 37.8 degrees C (34-39.1 degrees C) despite modification with paracetamol. Within each child there was a positive relationship between rectal temperature and energy expenditure, energy expenditure increasing by a mean of 7.4% per degree C. There was no evidence of significant relationships between rectal temperature and CMRO2, CBF, or ICP. Mild induced hypothermia in two children did not result in decreased CMRO2 or CBF measurements. The efficacy of interventions aiming to modify cerebral energy metabolism by changing core temperature cannot be readily assessed by the response of the whole body.

The effect of severe head injury on whole body energy expenditure and its possible hormonal mediators in children.

This study examines the effects of severe head injury in children on whole body energy expenditure and the mediators that influence this. One hundred five serial measurements of whole body energy expenditure and plasma adrenaline, triiodothyronine, glucagon, cortisol, insulin, and growth hormone concentrations were made in 18 children aged 2-15 y receiving neurointensive care for severe head injury. Energy expenditure was measured using indirect calorimetry by a modified Douglas bag technique, and hormones were measured by RIA or radioenzymatic assay. Energy expenditure varied markedly between and within children (mean 97% of predicted, range 60-137%) and was significantly lower in the four children with a poor outcome (p = 0.03). Within each child there were statistically significant positive relationships between energy expenditure and adrenaline (p < 0.0001), triiodothyronine (p < 0.0001), and glucagon (p < 0.0001). However, there was evidence that the effect of adrenaline on energy expenditure was attenuated. This may be due to the effects of the cerebral trauma itself on central nervous influences on energy expenditure, to interactions between hormones, or to a global impairment of O2 utilization by the body's tissues.

Use of low dose arginine vasopressin to support brain-dead organ donors.

In a prospective study, we documented the hemodynamic effects of conventional donor maintenance in 24 brain-dead organ donors. Patients were then randomized to receive either saline or a low dose arginine vasopressin (AVP) infusion. In the AVP group (n = 11), plasma hyperosmolality decreased (P < 0.05), blood pressure increased (P < 0.01), inotrope use decreased (P < 0.01), and cardiac output was maintained. In the control group (n = 13), plasma hyperosmolality increased (NS); no significant change in blood pressure, cardiac output, or inotrope infusion rate occurred. Myocardial ATP levels were higher in the AVP than the control group (NS). Early organ function was similar in the 2 groups. We conclude that the use of a low dose AVP infusion enables inotrope use to be reduced and recommend consideration be given to the use of a low dose AVP infusion in potential thoracic organ donors.

Haemodynamic responses to surgery in brain-dead organ donors.

In a prospective study we documented the haemodynamic response to surgery in 14 brain-dead organ donors. The haemodynamic responses to the first 30 min of surgery were predominantly due to alterations in vascular resistance. The mean systemic vascular resistance increased significantly (p = < 0.01) from 936 to 1217 dyn.s.cm-5 after 6 min, then decreased significantly (p = < 0.001) to 642 dyn.s.cm-5 after 30 min of surgery. In two patients, the decrease in systemic vascular resistance was associated with haemodynamic decompensation. The left cardiac work index increased significantly (p = < 0.05) during surgery. We conclude that retrieval surgery causes significant haemodynamic effects. The early effects are predictable and may jeopardise organ perfusion. We advance arguments that organ preservation may be compromised by the use of inotropic agents. When practical, we suggest that a pulmonary artery catheter should be used during retrieval surgery in multi-organ donors to facilitate a reduction in the use of inotropic drugs.

The effect of fluid therapy on alveolar arterial oxygen gradient in brain-dead organ donors.

Lung transplantation is limited by a shortage of suitable lung donors. Fluid loading is widely used to increase blood pressure during donor maintenance. In a prospective study, we investigated the effect of fluid loading with lactated Ringers solution on pulmonary function in 26 brain-dead adult organ donors. In all patients, the initial central venous pressure (CVP) was < 6 mmHg. In 13 patients, a CVP of 8-10 mmHg was achieved and maintained for 90 min by an infusion of lactated Ringers solution. This resulted in a significant increase (P < 0.05) in the alveolar arterial oxygen gradient. In 13 patients, the CVP was maintained at 4-6 mmHg for 90 min by, if necessary, an infusion of lactated Ringers solution. In these patients, no significant change in the alveolar arterial oxygen gradient occurred. Pulmonary gas exchange has been shown to be a reliable means of evaluating donor lung function. We conclude that crystalloid fluid loading to a CVP of 8-10 mmHg may be deleterious to lung function and should be avoided in potential lung donors.

Phrenic neuropathy in association with diabetes.

We report the case of a 51-year-old man who presented with breathlessness on exertion and orthopnoea in association with Type 2 diabetes mellitus. Investigation showed bilateral diaphragmatic paralysis due to phrenic neuropathy. There was no evidence of neuropathy or microvascular disease elsewhere. Phrenic neuropathy may be an important, albeit rare, complication of diabetes and diaphragmatic function should be considered in any patient with unexplained breathlessness and orthopnoea.

Neuromuscular disease, respiratory failure and cor pulmonale.

Respiratory muscle weakness is an uncommon cause of chronic respiratory failure and a rare cause of cor pulmonale. The problem may not be apparent unless specific physical signs are sought or appropriate investigations performed. We present three patients who presented diagnostic difficulty for prolonged periods until the presence of respiratory muscle weakness was considered. Once the diagnosis was established treatment with nocturnal nasal intermittent positive pressure ventilation produced a dramatic improvement in symptoms and allowed a return to a near normal lifestyle.

Cold intolerance in patients with angina pectoris: effect of nifedipine and propranolol.

Fifteen patients with chronic stable angina pectoris and a history of reduced exercise tolerance in cold weather (cold intolerance) underwent symptom limited treadmill exercise tests at 20 degrees C and 0 degrees C in a specially constructed cold chamber while taking no antianginal medication. Their mean time to onset of angina (5.8 v 4.2 min), to 1 mm ST depression (5.1 v 3.8 min), and to peak exercise (7.4 v 5.7 min) was significantly shorter on exercise at 0 degrees C than at 20 degrees C. The double product of heart rate and systolic blood pressure at each of these end points was the same in both exercise tests. Eight of these patients were treated with nifedipine 10 mg three times a day for two weeks and then with propranolol 40 mg three times a day for another two weeks. Repeat exercise testing was performed at the end of each two week treatment period. The mean time (SD) to peak exercise at the end of the nifedipine treatment period was 9.1 (2.0) min at 20 degrees C and 8.5 (2.3) min at 0 degrees C. The double product at peak exercise was the same for both exercise tests. At the end of the propranolol treatment period the mean time to peak exercise was significantly less at 0 degrees C (7.8 (2.6) min) than at 20 degrees C (8.9 (2.4) min). The double product at peak exercise was the same for both exercise tests but was significantly less than that on nifedipine. Cold intolerance was shown in patients with a positive history by symptom limited treadmill exercise testing at 0 degrees C. It persisted when they were treated with propranolol, albeit to a lesser extent, but not when they were treated with nifedipine.

Alfentanil for caesarean section complicated by severe aortic stenosis. A case report.

Alfentanil 35 micrograms kg-1, was used successfully in a patient with severe aortic stenosis, in order to minimize the haemodynamic responses to intubation and surgery during Caesarean section. The baby was delivered apnoeic, unresponsive and with poor muscle tone, but responded rapidly to naloxone. Plasma alfentanil concentrations and percentage binding to plasma proteins were measured in both maternal and neonatal blood. Free drug concentrations were similar in both mother and neonate, but maternal plasma proteins had a higher affinity for alfentanil. Only 67.26% of neonatal plasma alfentanil was bound to plasma protein. This value did not differ significantly from those estimated from the blood of a further 12 healthy neonates.