PubMed Health⌕ Search

Biomedical subjects

M P Samuels

Publications and source records attributed to M P Samuels.

At least 55 records · Page 3Linked to original sources
PubMed1992

Fourteen cases of imposed upper airway obstruction.

Imposed upper airway obstruction was diagnosed as the cause of recurrent and severe cyanotic episodes in 14 patients. Episodes started between 0.8 and 33 months of age (median 1.4) and occurred over a period of 0.8 to 20 months (median 3.5). Diagnosis was made by covert video surveillance, instituted after either (a) the observation that episodes began only in the presence of one person, or (b) characteristic findings on physiological recordings, lasting between 12 hours and three weeks, performed in hospital or at home. Surveillance was undertaken for between 15 minutes and 12 days (median 24 hours) and resulted in safety for the patient and psychiatric assessment of the parent: mother (n = 12), father (n = 1), and grandmother (n = 1). These revealed histories of sexual, physical, or emotional abuse (n = 11), self harm (n = 9), factitious illness (n = 7), eating disorder (n = 10), and previous involvement with a psychiatrist (n = 7). Management of the abusing parents is complex, but recognition of their psychosocial characteristics may allow earlier diagnosis. Imposed upper airway obstruction should be considered and excluded by physiological recordings in any infant or young child with recurrent cyanotic episodes. If physiological recordings fail to substantiate a natural cause for episodes, covert video surveillance may be essential to protect the child from further injury or death.

Airway Obstruction↗
PubMed1992

Sleep related upper airway obstruction and hypoxaemia in sickle cell disease.

A cohort of 53 patients (age range 1.9-16.5 years) with sickle cell disease (49 homozygous SS and four S beta zero-thalassaemia) was studied for evidence of sleep related upper airway obstruction (UAO). This involved (i) a clinical assessment based on a history of snoring, a score of tonsillar size, and (for 50 patients) overnight multichannel respiratory recordings, and (ii) a blinded analysis of arterial oxygen saturation (SaO2) from the above recordings, and comparison with results from 50 healthy age matched controls of both white (n = 25) and Afro-Caribbean race. There was no difference in the baseline SaO2 values of the white and Afro-Caribbean controls. Eighteen patients with sickle cell disease (36%) were found to have sleep related UAO. The blinded analysis showed that eight patients (16%) had episodic hypoxaemia (SaO2 less than or equal to 80%, a value not observed in controls) and/or low baseline SaO2 values (less than 95.8%, the lowest value seen in the controls). Postoperative assessment was undertaken in 15 patients who underwent adenotonsillectomy. All demonstrated an improvement in symptoms and a reduction or abolition of episodic hypoxaemia. Of the 47 patients assessed when free of UAO (not demonstrated on screening, n = 32, or resolved following surgery, n = 15), seven continued to show baseline hypoxaemia. Sleep related UAO and baseline hypoxaemia are common complications of sickle cell disease in children.

Age Factors↗
PubMed1992

Negative extrathoracic pressure ventilation for phrenic nerve palsy after paediatric cardiac surgery.

OBJECTIVE: To investigate the feasibility of negative extrathoracic pressure ventilation as a respiratory support following phrenic nerve palsy after cardiac surgery. DESIGN: An uncontrolled pilot study. PATIENTS: 14 patients aged one week to 30 months (median 5.3 months) with phrenic nerve palsy diagnosed by phrenic nerve conduction tests and diaphragmatic electromyograms. Four had bilateral and 10 unilateral palsy. Before treatment all required oxygen and 10 were receiving positive pressure ventilation. One of the patients with bilateral and four of the patients with unilateral palsies had undergone a plication before negative pressure ventilation was started. INTERVENTION: Treatment was started 6-65 days (median 23) after operation with a newly designed system which included a Perspex chamber, which gave easy access to the child, and an elastic latex neck seal. Continuous negative pressure was used in conjunction with intermittent positive pressure ventilation while continuous or intermittent negative pressure ventilation was used in extubated infants. RESULTS: All four patients with bilateral palsy survived with long-term intermittent negative pressure ventilation and did not require further surgery. Of the 10 with unilateral lesions, seven required no further surgery, two underwent plication, and one had a re-plication. Three patients with unilateral palsy died of non-respiratory causes. The duration of positive pressure ventilation after starting negative pressure ranged from 0 to 23 days (median 6). Treatment with negative pressure lasted for 3-241 days (median 32) and was predominantly administered off the intensive care unit, including at home. CONCLUSIONS: Negative pressure ventilation may be an alternative to positive airway pressure ventilation in the management of phrenic nerve palsy. A multicentre randomised controlled trial is now required to assess further the role of negative pressure ventilation in phrenic nerve palsy.

Child, Preschool↗
PubMed1992

Potential role of intrapulmonary shunting in the genesis of hypoxemic episodes in infants and young children.

A number of physiologic phenomena during some apneic/cyanotic episodes in infants and young children cannot be explained sufficiently on the basis of a cessation or reduction in alveolar ventilation alone. These include (1) the extremely rapid development of hypoxemia during some episodes, (2) the occurrence of hypoxemic episodes despite continuous ventilation, (3) differences in the speed of desaturation between different forms of apneic episodes, (4) the presence of continued breathing efforts and yet absent airflow despite bypass of the upper airway, and (5) evidence that apnea and hypoxemia may begin simultaneously. Potential mechanisms to explain these phenomena include the sudden development of an unevenness in the matching between ventilation and lung perfusion, the flow of blood through unventilated areas of lung, and a sudden impairment in gas diffusion. Evidence from physiological and morphological studies suggests that all of these mechanisms, although to a different extent, may be involved in apneic/cyanotic episodes. The recognition that nonapneic mechanisms can cause sudden profound hypoxemia may alter our approach to the identification, treatment, and prevention of these episodes.

Apnea↗
PubMed1991

Sleep related upper airway obstruction in a cohort with Down's syndrome.

The prevalence of sleep related upper airway obstruction (UAO) was studied in a cohort of 34 children with Down's syndrome from a geographically defined area. Thirty two (94%) of the children, ranging in age between 0.1 and 4.9 years (median 1.4), underwent full clinical assessment for UAO including parental questionnaires and overnight tape recordings of chest wall movements and arterial oxygen saturation (SaO2). Compared with controls, children with Down's syndrome had (a) an increased incidence of stridor and chest wall recession during sleep, (b) an increased frequency of a pattern on inspiration indicating increased upper airway resistance, (c) a reduced baseline oxygen saturation (having excluded recordings on four children with potential for right to left intracardiac shunting), and (d) an increased number of episodes with SaO2 less than or equal to 90% despite continued chest wall movements. At their initial assessment seven children (22%) had evidence of UAO. The 18 youngest children (less than or equal to 1.7 years) underwent repeated recordings and clinical assessment until they had all reached 2 years of age. A further three were found to have developed UAO. Sleep related UAO is a common problem in children with Down's syndrome, occurring in 10 of 32 (31%) of this population based sample.

Airway Obstruction↗
PubMed1991

Home monitoring of transcutaneous oxygen tension in the early detection of hypoxaemia in infants and young children.

Twenty three patients (age range 0.5-40 months) with recurrent cyanotic episodes underwent physiological recordings, including transcutaneous oxygen tension (TcPO2) from a monitor modified for use at home (Kontron 821S). Of 69 episodes in which the arterial oxygen saturation (SaO2, Nellcor N200) was less than or equal to 80% for greater than or equal to 20 seconds and/or central cyanosis was present, the TcPO2 monitor alarmed (less than or equal to 20 mmHg or 2.67 kPa) in every episode. The pulse oximeter identified hypoxaemia in 62 out of 69 episodes, failing in seven episodes due to signal loss from movement artefact. In only seven of 69 episodes was there an accompanying apnoeic pause (greater than or equal to 20 seconds), and heart rate fell to less than or equal to 80 beats/minute in only five of 28 episodes in which an electrocardiogram was recorded. In 32 episodes in which SaO2 fell to less than or equal to 60%, the TcPO2 monitor alarmed after a median time interval of 16 seconds (maximum time interval 30 seconds). The TcPO2 monitor was then used in an uncontrolled trial at home in 350 patients at increased risk of sudden death and/or hypoxaemia. Indications for monitoring included apparent life threatening events or cyanotic episodes (n = 163), prematurity and prematurity related disorders (n = 86), and sudden unexpected death in one or more siblings (n = 122). The TcPO2 monitor detected cyanotic episodes at home in 81 patients, 52 of whom received vigorous stimulation and/or mouth to mouth resuscitation. Twenty one of these 52 patients had further hypoxaemic episodes documented in hospital with pulse oximetry. In 30 patients, the TcPo2 monitor also identified the gradual development of hypoxaemia, as confirmed by pulse oximetry. Twenty of these needed additional inspired oxygen and six subsequently needed ventilatory support in hospital. This TcPo2 monitor is a reliable detector of both sudden and gradual onset hypoxaemia and is able to be used by parents in the home.

Child, Preschool↗
PubMed1990

Investigation of cyanotic/apneic episodes and sleep-related upper airway obstruction by long-term non-invasive bedside recordings.

Over a 4 year period, investigations were performed on 226 infants and children suffering cyanotic episodes and 160 suspected to be the victims of sleep-related upper airway obstruction. These investigations have been considerably aided by long-term tape recordings of multiple cardiorespiratory and neurophysiological variables from non-invasive sensors. In addition to identifying the underlying mechanisms responsible for cyanotic episodes, recordings have identified the presence or absence of airway obstruction, documented its severity by its effects on oxygenation and on sleep-state organization, and evaluated objectively the effects of treatment. The recording system, which is transportable, has been especially developed for use outside of the specialized sleep laboratory and was used on patients in hospital wards and at home.

Airway Obstruction↗
PubMed1990

Endoscopic evaluation and treatment of sleep-associated upper airway obstruction in infants and young children.

A method is described for observing the pharyngeal airway in children with proven sleep apnoea using a flexible nasendoscope during light anaesthesia. Fifteen children were referred for endoscopic evaluation and treatment. All had documented obstructive sleep apnoea. Flexible endoscopic assessment of the airway revealed the site of obstruction in all cases and allowed a rational and successful management plan. The mechanism of obstructive sleep apnoea in infants and young children is discussed and the findings at endoscopy and results of treatment are reported.

Adenoidectomy↗
PubMed1990

Recurrent cyanotic episodes with severe arterial hypoxaemia and intrapulmonary shunting: a mechanism for sudden death.

The pathophysiology of recurrent cyanotic episodes has been investigated in 51 infants and children. Episodes began at a median age of 7 weeks (range 1 day to 22 months, 39 at less than 4 months). They were characterised by the rapidity of onset and progression of severe hypoxaemia with early loss of consciousness from cerebral hypoxia. The most common precipitating factor was a sudden naturally occurring stimulus from pain, fear, or anger. In uncontrolled trials, cyanotic episodes were reduced in frequency and severity by tetrabenazine (n = 15) and additional inspired oxygen (n = 10). Eight patients died suddenly and unexpectedly (four during cyanotic episodes). Twenty eight patients underwent physiological studies during cyanotic episodes. There was no evidence of seizure activity at the onset and although prolonged absence of inspiratory effort with continued expiratory efforts was common, breathing sometimes continued. Episodes were not caused by upper airway obstruction and sometimes occurred during positive airway pressure ventilation. The rapidity of fall in arterial oxygen pressure and continued breathing suggested a right to left shunt of sudden onset. The results of contrast echocardiography and lung imaging studies confirmed that this was occurring within the lungs. These cyanotic episodes included both intrapulmonary shunting and prolonged expiratory apnoea. They are best explained by interactions between central sympathetic activity, brainstem control of respiration and vasomotor activity, reflexes arising from around and within the respiratory tract, and the matching of ventilation to perfusion in the lungs. They are a cause of sudden unexpected death in infancy and early childhood.

Child↗
PubMed1989

Negative extrathoracic pressure in treatment of respiratory failure in infants and young children.

OBJECTIVE: To assess the efficacy of a newly developed system for applying continuous or intermittent negative (subatmospheric) extrathoracic pressure in respiratory failure. DESIGN: Uncontrolled clinical trials in infants deteriorating or failing to improve despite standard medical treatment. SETTING: Paediatric and neonatal intensive care units and paediatric wards. PATIENTS: 88 Infants and young children aged 1 day to 2 years with respiratory failure due to bronchopulmonary dysplasia, the neonatal respiratory distress syndrome, bronchiolitis, myopathy, the congenital hypoventilation syndrome, pneumonitis, and postoperative phrenic nerve palsy. At the start of treatment 59 were receiving greater than or equal to 50% inspired oxygen and 40 positive airway pressure ventilation. INTERVENTION: Treatment was provided within purpose built Perspex chambers of appropriate size. The chamber incorporated safe and effective latex neck seals; facilities for access, monitoring, and observation; and a heater to control the ambient air temperature. MAIN OUTCOME MEASURES: Inspired oxygen concentration and carbon dioxide pressure before application of negative extrathoracic pressure and two and 48 hours afterwards; duration of treatment; and final outcome (discharge home or death). RESULTS: While arterial oxygen saturation was maintained at constant values 75 infants showed reductions in inspired oxygen concentrations (range 4-50%, median 15%) two hours after starting treatment and 74 showed reductions at 48 hours (2-79%, median 20%). Of 59 infants who had carbon dioxide pressure measured before and after starting negative extrathoracic pressure, 21 showed a reduction (range 0.6-8.9 kPa, median 2.0), 30 no change (+/- 0.5 kPa), and eight a rise (range 0.6-5.1 kPa, median 2.1). In 28 patients extubation was facilitated, 54 patients were discharged home, where six continued treatment, and 34 died. Treatments lasted for between two and 236 days (median 13 days). CONCLUSION: Negative pressure respiratory support is a non-invasive yet effective treatment for respiratory failure. It may avoid the need for intubation, reduce the pathophysiological consequences of positive airway pressure ventilation, and aid extubation.

Child, Preschool↗