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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Appropriate management of intracranial pressure (ICP) in severely head injured patients depends in part on the cerebral vessel reactivity to PCO2; loss of CO2 reactivity has been associated with poor outcome. This study describes a new method for evaluating vascular reactivity in head-injured patients by determining the sensitivity of ICP change to alterations in PCO2. This method was combined with measurements of the pressure volume index (PVI), which allowed calculation of blood volume change necessary to alter ICP. The objective of this study was to investigate the ICP response and the blood volume change corresponding to alterations in PCO2 and to examine the correlation of responsivity and outcome as measured on the Glasgow Outcome Scale. The PVI and ICP at different end-tidal PCO2 levels produced by mild hypo- and hyperventilation were obtained in 49 patients with Glasgow Coma Scale scores of less than 8 and over a wide range of PCO2 (25 to 40 mm Hg) in eight patients. Given the assumption that the PVI remained constant during alteration of PaCO2, the estimated blood volume change per torr change of PCO2 was calculated by the following equation: BVR = PVI x delta log(ICP)/delta PCO2, where BVR = blood volume reactivity. The data in this study showed that PVI remained stable with changes in PCO2, thus validating the assumption used in the blood volume estimates. Moreover, the response of ICP to PCO2 alterations followed an exponential curve that could be described in terms of the responsivity indices to capnic stimuli. It was found that responsivity to hypocapnia was reduced by 50% compared to responsivity to hypercapnia measured within 24 hours of injury (p < 0.01). The sensitivity of ICP to estimated blood volume changes in patients with a PVI of less than 15 ml was extremely high with only 4 ml of blood required to raise ICP by 10 mm Hg. The authors conclude from these data that, following traumatic injury, the resistance vessels are in a state of persistent vasoconstriction, possibly due to vasospasm or compression. Furthermore, BVR correlates with outcome on the Glasgow Coma Scale, indicating that assessment of cerebrovascular response within the first 24 hours of injury may be of prognostic value.
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PMID:Cerebrovascular carbon dioxide reactivity assessed by intracranial pressure dynamics in severely head injured patients. 859 44

In a brain-dead patient, a 42-year-old woman who went into a coma after a cervical foraminotomy, spinal automatisms were seen which cast doubt on the diagnosis of brain death. The procedure which was to lead to organ transplantation was seriously disturbed. In brain-dead patients spinal automatisms appear earlier and are more often present than deep tendon reflexes. Due to the developing hyperreflexia spinal automatisms can be elicited more easily and from a larger skin area as the period of brain death lasts longer. Spinal automatisms can also appear spontaneously and can be generated by hypercapnia. If criteria for brain death are met, these movements are no reason to reconsider the diagnosis of brain death.
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PMID:[Unexpected movements in a brain-dead patient]. 827 99

A case of severe accidental hypercapnia during anesthesia is presented. A 44-year-old woman underwent laparotomy under general anesthesia. Forty minutes after the start of the operation, BP rose slightly and HR increased from 110 to 140 x min-1. Then ST segment depression was noted on ECG monitor. Therefore, nitrous oxide was discontinued for 20 minutes. Frequent oxygen supply with oxygen flush was needed to inflate the collapsed bag. The operation was concluded without additional clinical problems. The patient remained unconscious after the anesthetics were discontinued. Cyanosis was observed despite the delivery of 100% oxygen. Cardiac arrest occurred following abrupt bradycardia, but she responded immediately to resuscitation. She was in a deep comatose state and did not respond to painful stimuli. The pupils were fully dilated with absent light reflex. Arterial blood gas analysis revealed; pH 6.720, PaCO2 277 mmHg, PaO2 159 mmHg, and BE-16.2. Disconnection of anesthetic circuit was noted, thereafter, and hyperventilation was performed. Then, the pupils became promptly constricted and the response to painful stimuli appeared within 30 minutes. Her level of consciousness recovered completely after 4.5 hours of hyperventilation. She suffered from refractory hypotension (BP70-85 mmHg in systolic pressure) in spite of catecholamine administration, tachycardia (HR 140-160 x min-1) and ARDS in the ICU, but all the symptoms disappeared by the 16 hours after ICU admission.
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PMID:[A patient who manifested various symptoms following severe accidental hypercapnia]. 899 34

The feasibility of intratracheal pulmonary ventilation (ITPV) was tested in five ventilated moribund neonatal and pediatric patients with uncontrollable hypercapnia: a 2-year-old child, a 52-day-old infant, and three premature infants (29, 29, and 26 weeks gestation; 1300 g, 1100 g and 890 g birth weight, respectively). ITPV was applied for 9.5, 8, 25, 58.5, and 47.5 hr, respectively. An intratracheal catheter (Cook Critical Care, Inc., Bloomington, IN) with a reversed continuous flow of gas at its tip (away from the lungs) allowed flushing of CO2 from the proximal dead space. Marked reductions in Paco2, ranging from 37% to 71% and improvement in pH were achieved within 4-6 hr of applying ITPV. During ITPV, the mean lowest Paco2 was significantly less than the pre-ITPV Paco2 (p < 0.0017), and the mean best pH was significantly higher than the pre-ITPV pH (p < 0.015). In four patients, despite significant reductions in Paco2, there was no substantial improvement in their baseline condition (shock and severe metabolic acidosis or coma) and they were switched back to conventional ventilation. This led to worsening hypercapnia to pre-ITPV values. These four patients subsequently died. It is possible that these patients were already too ill to derive significant benefit from the technique. One premature infant survived, was successfully weaned to conventional ventilation and was eventually discharged home. ITPV can alleviate uncontrollable hypercapnia in ventilated neonatal and pediatric patients.
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PMID:Intratracheal pulmonary ventilation in premature infants and children with intractable hypercapnia. 946 6

Head injuries in adolescents, which often result from motor vehicle accidents, sports injuries, falls, burns, or trauma due to violence, may range from mild to severe to fatal. One of the most useful initial scoring systems is the Glasgow Coma Scale. Proper care of the injured adolescent begins at the scene of the incident, with an emphasis on management of the airways, breathing, and circulation (the ABCs) and prevention of secondary injury, which may result from hypoxia, hypercarbia, rapid swings in blood pressure, hypovolemia, seizures, and poor or improper immobilization. Monitoring and management of intracranial pressure become a priority on arrival at the emergency department. Imaging techniques, such as CT scan, may be necessary. Injuries to the neck (cervical spine), which may result in quadriplegia, should be suspected in the presence of neurologic deficits.
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PMID:Adolescent Head and Neck Trauma. 1035 4

Trauma victims are directly transferred to a level I trauma center bypassing local hospitals. First, airways and cervical stability are secured. Intracranial hematoma should be promptly evacuated. Endotracheal intubation and mechanical ventilation are initiated for children with a Glasgow Coma Score of 10 or less, anisocoria, apnea, and/or hypercarbia. Isotonic crystalloid is used for intravenous fluid maintenance. The goal of intracranial pressure (ICP) management is to maintain the ICP at less than 15 mmHg and to maintain minimum cerebral perfusion pressure at 45-55 mmHg. External ventricular drainage provides direct control of the ICP by allowing intermittent drainage of the CSF (5-10 ml/hour). Mannitol is effective but hyperventilation is not recommended.
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PMID:[Management of acute-stage head trauma in childhood]. 1072 87

Advanced prehospital emergency medical care of patients with a severe head injury must essentially focus on the impact of secondary cerebral insults of systemic origin on the outcome. The first objective of prehospital care is to prevent hypoxaemia and hypercapnia. Therefore, all patients with a Glasgow Coma Scale score equal to or lower than 8 must be treated with endotracheal intubation and controlled ventilation under continuous monitoring of SpO2 and PETCO2. Treatment is similar in head-injured patients with significant deterioration of consciousness level, seizures, respiratory distress, or severe facial and thoracoabdominal injuries. The endotracheal tube is inserted by the orotracheal route under direct laryngoscopy, after a rapid induction sequence of anaesthesia and immobilization of the cervical spine in neutral position. For the induction of anaesthesia in these high-risk patients (full stomach, unknown medical history, deteriorated haemodynamic status), etomidate and suxamethonium are the preferred agents. Sedation is maintained with an hypnoticopioid association (fentanyl). Simultaneously, the main goal is the maintenance of an optimal cerebral perfusion pressure, as arterial hypotension severely worsens cerebral ischaemia. Volume loading is accomplished with 0.9% saline and hydroxyethyl starch.
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PMID:[Prehospital management of patients with severe head injuries]. 1083 14

There is no question that substantial progress has been made over the last 30 years, since the pioneering multinational studies of Jennett and colleagues, in our understanding of the mechanisms involved in the production, progression, and amelioration of brain damage. The introduction of computed tomography and simple but elegant classifications of the severity of injury (e.g., the Glasgow Coma Scale and the Glasgow Outcome Scale) were seminal milestones in neurotraumatology. When neurosurgeons such as Langfitt, Becker, and Miller took advantage of the pioneering investigations of intracranial hypertension by Janny and Lundberg and combined them with imaging, classification of brain damage, and improvements in emergency medical services, substantial gains were soon made. However, given the perspective of the beginning of the 21 st century, one can see those gains as relatively straightforward, as they have required the consolidation of concepts and ideas that fit together relatively easily. Better attention to easily delineated abnormalities, such as shock, hypoxia, and hypercarbia, and the early evacuation of mass lesions coupled with the concurrent development of modern principles of critical care account for substantial reductions in mortality and a reduction in the number of vegetative, contracted, spastic survivors. Future improvement in the care of patients with head injuries will increasingly be dependent on advances in molecular neurobiology and psychology, our ability to successfully modulate genetic expression, and progress in the treatment of related illnesses, such as stroke, subarachnoid hemorrhage, depression, and Alzheimer's disease.
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PMID:Head injury: recent past, present, and future. 1098 41

The initial management of severely head-injured patients, including infants and children, is aimed at preventing and treating secondary brain damage, which mainly result from systemic insults (hypoxaemia, hypercarbia, arterial hypotension). Orotracheal intubation, followed by continuous sedation-analgesia, is mandatory when the Glasgow Coma Scale score (GCS) is less than or equal to 8 (crush induction is recommended). The goal of mechanical ventilation is to maintain normoxaemia and normocarbia. Moreover, the maintenance of an optimal cerebral perfusion pressure, usually 50 mmHg in infants, requires volume loading (isotonic fluids and colloids), and catecholamines if arterial hypotension persists. Intravenous mannitol is used only in case of life threatening intracranial hypertension, keeping in mind the potential for aggravating an hypovolaemia. Cerebral tomodensitometry is the most relevant imaging procedure for diagnosing surgical brain lesion. However, it should be noted, that severe head trauma is frequently associated with extra-cranial traumatic injuries, which may be responsible for (avoidable) deaths if the diagnosis is not made or delayed. Therefore, infants and small children presenting with severe head trauma should be considered as multiple injured and treated accordingly. Adequate initial management of severely head-injured children may participate to improved neurological outcome.
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PMID:[Severe head injuries in the young child: early management]. 1191 73

The brain of neurosurgical patients are exposed to various manipulations in the ICU or during surgery. Under such conditions brain O2 balance may become negative and as a result brain vitality and function will deteriorate. In order to evaluate brain vitality in real time it is important to measure more than one parameter. The multiparametric monitoring system used in our previous study to monitor comatose patients (Mayevsky et al., Brain Res. 740: 268-274, 1996) was changed into a "simplified" tissue spectroscope for real time monitoring of brain O2 balance. Mitochondrial function was evaluated by monitoring the NADH redox state by surface fluorometry. Microcirculatory blood flow was assessed by laser Doppler flowmetry. The combined optical probe was located on the surface of the brain during various neurosurgical procedures and the responses were recorded and presented in real time to the surgeon. A total of 32 patients were monitored during various procedures. The results could be summarized as follows: 1. Hypercapnia led to 3 different types of responses. In two patients the 'stealing' like event was recorded. In the other 7 patients the responses to high CO2 was not detectable. In the last group of 6 patients a clear CBF elevation was recorded with variable response of mitochondrial NADH. 2. Our monitoring device was able to evaluate the efficacy of the STA-MCA anastomosis during aneurysm surgery. 3. A significant correlation was recorded between CBF and NADH redox state during changes in blood pressure, papaverine injection, spontaneous drop in blood supply to the brain or during releasing of high ICP levels. We conclude that in order to evaluate the metabolic state of the brain during neurosurgical procedures it is necessary to monitor both CBF and mitochondrial NADH by using the tissue spectroscope.
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PMID:The evaluation of brain CBF and mitochondrial function by a fiber optic tissue spectroscope in neurosurgical patients. 1216 49


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