[Laboratory diagnostics in transient loss of consciousness : Serum lactate compared to serum creatine kinase as diagnostic indicator for generalized tonic-clonic seizures]

BACKGROUND

Laboratory parameters can help in the differential diagnostics of acute episodes of transient loss of consciousness. Especially serum lactate and serum creatine kinase (CK) levels may provide valuable hints to distinguish generalized tonic-clonic seizures (GTCS) from syncope.

MATERIAL AND METHODS

Serum lactate levels at admission and CK levels 10-48 h after the episodes that led to admission were compared between patients with GTCS (n = 30) and those with syncope (n = 15). In addition, sensitivity and specificity of lactate and CK as diagnostic markers for syncope and GTCS were determined.

RESULTS

The serum lactate and serum CK levels were significantly increased in patients with GTCS as compared to syncope patients (serum lactate: p < 0.001; CK: p < 0.005). The area under the curve (AUC) for serum lactate as an indicator for GTCS was 0.94 (95% confidence interval [CI] 0.88-1.0). For CK the receiver operating characteristics (ROC) analysis produced an AUC of only 0.77 (95% CI: 0.63-0.9).

CONCLUSION

The determination of the lactate value as point-of-care diagnostics appears to be highly relevant in the rapid clarification of unclear episodes with transient loss of consciousness. The CK level at follow-up is also suitable for distinguishing GTCS from syncope but is inferior to the serum lactate value.

Profound hypoglycemia-ınduced by vaccinium corymbosum juice and laurocerasus fruit

An emergency intervention was performed in a 75-year-old male patient with hypoglycemic attack and blackout. Although he was diagnosed with prediabetes before 2 years, he did not take any anti-diabetic drug or follow dietary advice. He drank Vaccinium corymbosum L (VC) juice daily with a belief that it increases sexual potency. Before the development of hypoglycemia, the patient had consumed about 500 ml VC juice in addition to eating 200-300 gram of Laurocerasus officinalis (LO) fruit. The measured plasma glucose (PG) level during loss of consciousness was 30 mg/dl. The profound hypoglycemia may be an unexpected side effect of an interaction between the chemical compositions of the two plants, occurred as a result of LO fruit intake that may have a strong PG-lowering effect or related to excessive intake of VC juice. Both plants may be considered in the alternative treatment of diabetes.

Late postprandial hypoglycemia due to bioactive insulin dissociation from autoantibody leading to unconsciousness in a patient with insulin autoimmune syndrome

We report here the case of an 83-year-old man who was treated for unconsciousness and hypoglycemia (39 mg/dL) accompanied by marked elevation of serum immunoreactive insulin (IRI) (4,760 µIU/mL). We diagnosed his condition as insulin autoimmune syndrome (IAS, Hirata disease) because of a high insulin autoantibody (IAA) titer (>90%: bound/total) and no history of exogenous insulin administration. Reactive hypoglycemia occurred due to immediate association followed by dissociation between insulin and insulin autoantibodies after glucose or food intake. An α-glucosidase inhibitor in combination with frequent small meals reduced the postprandial hyperglycemia (glucose spike) and ameliorated the reactive hypoglycemia.

[Plasma catecholamines in consciousness recovery in patients with severe traumatic brain injury]

Changes in plasma noradrenalin (NA) and dopamine (DA) levels were evaluated in the stages of consciousness recovery in patients with severe traumatic brain injury with and without deep brain structure damage. Forty-eight patients (36 men and 12 women), aged from 12 to 56 (31,9±10,9) yeas, were enrolled in the study. Two variants of catecholamine (CA) changes were found: 1) a CA-dissociation that was oppositely directed to NA and DA changes was observed in unconsciousness; 2) a CA-dissociation (unidirectional NA and DA changes) that was observed after the restoration of consciousness. In patients with the damage of two frontal lobes and deep brain structures, CA-association periods were seen in the stage of mental confusion with psychomotor agitation or when the brain stem was damaged. The duration of CA-association was negatively correlated with the velocity, quality of consciousness recovery and outcomes evaluated by the Glasgow scale.

Retroperitoneal solitary fibrous tumor-induced hypoglycemia associated with high molecular weight insulin-like growth factor II

A man, aged 65 years, presented with frequent episodes of hypoglycemia and unconsciousness. Hypoglycemia was accompanied by undetectable serum insulin and C-peptide levels and a high serum insulin-like growth factor (IGF)-II level. He was found to have a retroperitoneal solitary fibrous tumor. He underwent successful resection of the tumor and had no hypoglycemic episodes after the operation. Immunohistochemical analysis revealed positive immunostaining for IGF-II in tumor cells. The presence of the high-molecular-weight form of IGF-II in the patient's serum was confirmed by immunoblotting, which suggests that his hypoglycemia was due to an increase in the plasma level of IGF-II secreted by the tumor.

CNS oxygen toxicity in closed-circuit diving: signs and symptoms before loss of consciousness

INTRODUCTION

There is a dearth of information regarding CNS oxygen toxicity accidents in closed-circuit oxygen diving. The aims of the present study were to report the sensations and symptoms that accompany CNS oxygen toxicity accidents, and to evaluate whether loss of consciousness can occur without any warning signs.

METHODS

We documented 36 CNS oxygen toxicity accidents in closed-circuit oxygen diving. The full accident inquiry included the first report from the diving unit, an interview of the victim and his buddy by the researchers, and an examination of the diving equipment.

RESULTS

The symptoms that appeared before termination of a dive, as reported by the victim or his buddy, were as follows (in descending order of frequency): limb convulsions; hyperventilation; difficulty maintaining a steady depth; headache; and visual disturbances. The symptoms that appeared after detachment from the mouthpiece were, in descending order of frequency: headache; loss of consciousness; confusion; weakness; dizziness; and facial muscle twitching and limb convulsions. A high inspired CO2 [mean 4.2 kPa (29.9 mmHg)] was connected with loss of consciousness. No dive was terminated before at least two symptoms (mean 3.4) had been noted a minimum of 5 min before termination.

DISCUSSION

Symptoms that are accepted as being related to CNS oxygen toxicity, as well as others such as headache, difficulty maintaining a steady depth, hyperventilation, weakness, and a choking sensation, were more frequent among the O2 accident victims compared with divers who did not interrupt their dives.

CONCLUSION

Awareness of any unusual sensation can prevent a potentially dangerous situation from arising.

Nitrous Oxide and Anesthetic Requirement for Loss of Response to Command During Propofol Anesthesia

The blood concentration associated with loss of response (LOR) to command in 50% of subjects (CP50(LOR)) is an important measure of anesthetic potency. We therefore determined the CP50(LOR) in 40 healthy surgical patients, aged 18-60 yr old, receiving propofol alone or propofol with 67% nitrous oxide (N2O). Patients were randomized to receive 100% oxygen or 67% N2O in oxygen via facemask. Three minutes later, a target-controlled propofol infusion was commenced at a concentration determined by the response of the previous patient in the same group. Fifteen minutes later, response to command was assessed by a blinded observer. Arterial blood samples were taken for propofol assay, and the bispectral index (BIS) was monitored continuously. At testing for response to command, both the measured and target propofol concentrations were significantly larger and BIS values significantly smaller in the propofol-alone group compared with the propofol-N2O group. The CP50(LOR) of propofol in the propofol-alone group was 4.58 mug/mL (95% confidence interval [CI], 1.14-15.36) and 2.67 microg/mL (95% CI, 2.28-3.17) in the propofol-N2O group. The BIS value when 50% of patients responded to command was 60 (95% CI, 55-65) in the propofol-alone group and 75 (95% CI, 73-83) in the propofol-N2O group.

S100B protein in carbon monoxide poisoning: a pilot study

Carbon monoxide (CO) poisoning is the most common form of lethal poisoning. The aim of this prospective clinical study was to assess the possible role of S100B, the structural protein in the astroglia, as a biochemical marker of brain injury in carbon monoxide poisoning. Serum S100B determination was performed in 38 consecutive patients poisoned by carbon monoxide who were admitted to the Emergency Department (ED) in Ljubljana. All three unconscious patients had elevated S100B levels. The patient with the highest S100B died. S100B was elevated in two of the six patients with initial transitory unconsciousness at the scene. All 29 patients without loss of consciousness had normal S100B levels. Carbon monoxide poisoning appears to be associated with elevated S100B levels.

PET quantification of muscarinic cholinergic receptors with [N-11C-methyl]-benztropine and application to studies of propofol-induced unconsciousness in healthy human volunteers

This work evaluated kinetic analysis methods for estimation of the receptor availability of the muscarinic receptor using dynamic positron emission tomography (PET) studies with [N-(11)C-methyl]-benztropine. The study also investigated the effect of propofol on central muscarinic receptor availability during general anesthesia. Six volunteers were scanned three times, once for baseline while awake, once during unconsciousness, and once after recovery to conscious level. An irreversible two-tissue compartment model was used to estimate the [N-(11)C-methyl]-benztropine specific binding rate constant k(3), a measure of muscarinic receptor availability. Two different estimation methods were used: 1) optimization with positivity constraints on all the parameters; 2) optimization with additional constraints determined from a one-tissue compartment fit to the cerebellum. In regions with low to middle muscarinic receptor density, the k(3) values from method (2) had lower standard errors than that for method (1) and gave a higher correlation with the density of muscarinic receptors measured in human tissue by in vitro studies (r(2) of 0.98 for Method 2 and r(2) of 0.72 for Method 1). But the k(3) values determined by Method 2 had higher errors for regions with high muscarinic receptor density compared to Method 1. For both methods the mean k(3) values during unconsciousness were generally lower than those during awake for most regions evaluated. Therefore, the method with additional constraints derived from the cerebellum (Method 2) was deemed superior for regions with low to middle muscarinic receptor density, while the method with positivity constraint is the better choice in the regions with high muscarinic receptor density. Our results also suggest the existence of propofol-related reductions in muscarinic receptor availability.

A case of severe hyperammonemia and unconsciousness following sodium valproate intoxication

Although valproic acid has gradually gained its popularity in the treatment of various seizure disorders, overdose of valproate is not common. An 18-y-old man with a history of epilepsy controlled by sodium valproate and clonazepam attempted suicide with an ingestion of 45 g sodium valproate. He presented to our service with drowsiness and irritability. Extremely high serum ammonia (623 ug/dL) and elevated serum valproate concentration (575 ug/mL) were found on admission. Several metabolic abnormalities, including hypernatremia, hypocalcemia and metabolic acidosis, as well as, increased serum transaminase levels were also recorded. With supportive measures, he became clear 24 h later and was discharged 6 d after ingestion. Serial follow-up of his serum valproate and ammonia levels disclosed a close relationship between these 2 measurables. After acute overdose of valproic acid, patients usually present with mild and generally reversible depression of the central nervous system. However, impairment of liver function, hyperammonemia, fluid-electrolyte disturbances, coma, seizures, hypotension and even death may occur following valproate overdose. Symptomatic and supportive measures are the mainstay in the treatment of valproic acid overdose. With prompt diagnosis and early institution of treatment, a complete recovery should be anticipated.

[Losing consciousness: role of the venous lactate levels in the diagnosis of convulsive crises]

OBJECTIVES

This prospective study was conducted to evaluate the usefulness of venous lactate assay in the diagnosis of generalized seizures.

PATIENTS AND METHODS

Over a three month period, 78 consecutive adults admitted to the emergency unit for unconsciousness were included in the study. Three study groups were defined: patients with generalized seizures (n = 22), unconscious patients without seizure (n = 34) and known epileptic patients with unexplained malaises (n = 22). Patients with a disease susceptible of increasing lactate levels were excluded. Peripheral venous blood was drawn to determine lactates, bicarbonates and pH on a blood gas analyzer. All determinations were performed within 5 minutes of blood withdrawal. CPK level was also determined with an enzymatic method.

RESULTS

In patients who had seizures, venous lactate levels were higher than those in patients who had no seizures: 4.3 +/- 0.5 mmol/l in generalized seizure patients versus 1.64 +/- 0.1 and 2.2 +/- 1.39 in unconscious patients without seizure and known epileptic patients with unexplained malaise respectively. The threshold lactate level of 2.5 mmol/l given by ROC curves gave a 0.97 specificity and a 0.73 sensitivity.

DISCUSSION

The acidosis observed in patients with generalized seizures results from the combined effects of respiratory and metabolic acidosis. High lactate level would be a consequence of hypoxemia, per seizure rise in catecholamines, and aerobic and anaerobic metabolism in muscles during the tonic-clonic phase. In patients presenting in an unconscious state, increased lactate levels, even when determined up to 2 hours after venous blood withdrawal, could be a useful parameter for the diagnosis of epileptic seizure.

Effects of carbon dioxide insufflation combined with changes in body position on blood gas and acid-base status in anesthetized llamas (Llama glama)

OBJECTIVE

To study the combined effects of intra-abdominal CO2 insufflation with changes in body position during laparoscopy in xylazine-ketamine-halothane anesthetized llamas.

STUDY DESIGN

Prospective, controlled study.

ANIMALS

Nine castrated, male llamas weighing 114 +/- 23 kg, 3 to 13 years old.

METHODS

Three llamas (preliminary study [PS] group) were used to study the effect of right, lateral, dorsal, and left lateral recumbency on gas exchange and acid-base status. The other six (experimental study [ES] group) were used to study the combined effects of changes in body position and CO2 insufflation to an intraabdominal pressure of 10 to 12 mm Hg. Heart rate, respiratory rate, and indirect arterial blood pressures (systolic [SAP], mean [MAP], and diastolic [DAP]) were recorded every 5 minutes during anesthesia. Arterial blood gases (PaO2 and PaCO2) and acid-base status (pHa and HCO3-) were measured immediately after induction of anesthesia and before each change of position.

RESULTS

In the PS group, significant decreases in SAP, MAP and PaCO2 and increases in PaO2 and pHa were observed when the llamas were turned from right lateral to dorsal recumbency. Values for HCO3- were lower than the postinduction values, but they remained unaffected by the changes in position. In the ES group, values for MAP were significantly lower when the llamas were placed in dorsal and left lateral recumbency than those observed during right lateral recumbency. Arterial O2 tension during right lateral recumbency was lower but returned to preinsufflation values when the llamas were placed in the dorsal position. All llamas recovered uneventfully within 30 minutes after termination of anesthesia.

CONCLUSIONS

Insufflation of CO2 and changing body position induce minor and transient changes in cardiovascular and respiratory function.

CLINICAL RELEVANCE

Laparoscopy with mild intra-abdominal CO2 insufflation (10 to 12 mm Hg) can be used safely in spontaneously breathing llamas anesthetized with xylazine, ketamine, and halothane.

Evaluation of pulse oximetry in anaesthetised foals using multiple combinations of transducer type and transducer attachment site

A commercially available pulse oximeter was evaluated in anaesthetised foals to determine its accuracy for estimating arterial haemoglobin saturation (SaO2). Five different transducer/transducer attachment site (TTAS) combinations were evaluated; 1-3) a fingertip transmission transducer attached to the foal's ear, lip and tongue, 4) an adhesive transmission transducer positioned on the foal's ear and 5) a forehead reflectance transducer placed on the ventral aspect of the foal's tail-base. Eight normal, Quarter Horse foals (age 5-10 days) were studied while under general anaesthesia. Alterations in arterial carbon dioxide tension (PaCO2) were produced by changing the level of ventilation. At each level of ventilation, alterations of arterial haemoglobin saturation (SaO2) were produced by varying the inspired fraction of oxygen (FIO2). At each level of ventilation and each level of FIO2, arterial blood samples were obtained for blood gas analysis while pulse oximeter readings were recorded simultaneously for each TTAS combination. Arterial blood oxygen saturation (SaO2) was calculated from arterial blood gas values and the equine blood oxygen dissociation curve. Pulse oximeter readings from each TTAS combination were compared with SaO2 values with linear regression analyses. Bias and precision values were determined and the sensitivity and specificity of each TTAS combination for detecting desaturation (SaO2 < 90%) were determined. Linear regression analyses indicated significant (P < 0.05) linear correlation between oxygen saturation determined by pulse oximeter (SpO2) and SaO2 for each of the 5 TTAS combinations. The combinations TTAS-1, TTAS-3 and TTAS-4 tended slightly to underestimate SaO2 at high SaO2 ranges, but overestimated SaO2 at low ranges of SaO2. Combination TTAS-2 overestimated SaO2 over all ranges of SaO2. Combination TTAS-5 consistently underestimated SaO2 at all ranges of SaO2. In general, accuracy and precision of each TTAS combination decreased at lower SaO2 ranges. All TTAS combinations, except TTAS-2 and TTAS-4, had good sensitivity for detecting SaO2 less than 90%. All TTAS combinations except TTAS-5 demonstrated good specificity. We concluded that pulse oximetry appears to be a valuable method for assessing SaO2 and detecting desaturation in anaesthetised foals. Clinicians should be aware that the type of transducer used and the anatomical site to which it is attached can have marked effects on the accuracy of pulse oximetry; and that different TTAS combinations may behave differently over various ranges of SaO2.

Drugs in blood samples from unconscious drug addicts after the intake of an overdose

This investigation includes whole blood samples from 53 drug addicts found unconscious in the Copenhagen area with evidence of a heroin overdose. Heroin/morphine was detected in 85% of the patients and other opioids in 11%. One or more benzodiazepines, most often diazepam, were detected in 75% of the patients. A blood alcohol concentration higher than 1.00 mg/g was detected in 57% of the patients. Methadone was detected in seven patients, ketobemidone in four, amphetamine in five and cocaine in one. This investigation showed widespread multi-drug abuse and heroin/morphine alone was detected in only one patient. As indicators of heroin intake, 6-mono-acetylmorphine (MAM) and morphine were detected in this investigation.

Arterial and jugular venous bulb blood propofol concentrations during induction of anesthesia

The aim of this study was to show that blood propofol concentrations at loss of consciousness vary with the rate of administration. Eighteen patients were allocated to receive a propofol infusion at 6 or 12 mg.kg-1.h-1 (approximately 8 and 15 mg/min) for induction of anesthesia. Propofol concentrations were analyzed from simultaneous arterial and jugular bulb venous blood samples. There were no significant differences in the dose of propofol administered to induce anesthesia (0.52 mg/kg both groups). However there were significant differences between the groups in the mean induction times (309 and 156 s), and in median arterial and venous concentrations at induction. Arterial concentrations were 1.93 and 2.70 and venous 1.11 and 1.51 micrograms/mL. There were no significant differences between the groups in the area between the arterial and venous time concentration curves from start of infusion to loss of consciousness (3.14 and 3.05 micrograms.mL-1.min-1). This study confirms that a target blood concentration of propofol cannot be identified with loss of consciousness under nonsteady state conditions. Both arterial and venous blood propofol concentrations at loss of consciousness depend on the rate of administration.

Ethanol-related visits by adolescents to a pediatric emergency department

The objectives of this study were to determine if the presence of ethanol (ETOH) in patients 10 to 20 years of age is associated with injury and if the patient's mental status reliably predicts their blood ethanol concentration. The study was designed as a retrospective, case-controlled report from a children's hospital emergency department. The data are from 45 patients 10 to 20 years old in whom ETOH was detected on toxic screen and 37 patients (N-ETOH) 10 to 20 years old in whom a toxic screen did not reveal ETOH. Injury occurred in 51% of the ETOH group and 8% (P = 0.0001) of the N-ETOH group. A correlation between blood ETOH level and mental status was found only at the extremes of blood ETOH levels. We conclude that the presence of ETOH may predispose adolescents to injury, requiring treatment in an emergency department. Except at the extremes of ETOH levels, mental status does not predict blood levels. A prospective assessment of mental status and blood ETOH levels in adolescents is needed before mental status assessment can replace the determination of blood ETOH concentrations.

Blood sampling procedures influence serum calcitonin concentrations in rats

The aim of this study was to determine whether serum calcitonin (S-CT) in rats is influenced by the method of taking blood samples. Sampling during halothane anaesthesia, after repeated administration of anaesthesia after a 14-day interval, and sampling without the use of anaesthetics (i.e. after the rats were made unconscious by stunning), resulted in different S-CT values (P < or = 0.001), whereas Ca2+ levels were not affected. In thyroidectomized rats, the S-CT values after stunning were not significantly different whereas those in sham-operated rats were different (P < or = 0.01). The possibility that anaesthesia may suppress stunning-induced changes in S-CT was explored in three other groups of rats subjected to halothane anaesthesia, stunning and stunning under halothane anaesthesia respectively. Although the S-CT level was highest after stunning and lowest in halothane-anaesthetized rats (P < or = 0.001), anaesthesia did not suppress the effect of stunning on S-CT. In conclusion the effect of sampling procedures must be considered in studies on the levels of S-CT in rats.

Acceleration-induced effects on baboon blood chemistry

Gravity-induced loss of consciousness (G-LOC) is known to have occurred in pilots since the early 1920's. Most of the research in this area has shown that G-LOC occurs due to a decrease in cerebral blood pressure and a concomitant reduction in brain perfusion. Since a reduction in cerebral blood flow can cause transient hypoxia, it is important to study the cerebral metabolism during high +Gz exposure. One component of these studies should include measurements of substrate availability and degradative products. In the present study, adult baboons were given multiple high +Gz exposures (2 to 6) using the Armstrong Laboratory human centrifuge. Venous blood was collected by an automatic syringe withdrawal pump before, during and after centrifuge exposures. The concentration of blood gases, glucose and lactate tended to decrease during the centrifuge exposure followed by an increase after the run. Total creatine kinase activity in serum was not significantly altered. These results suggest that during +Gz exposure, anaerobic glycolysis is stimulated resulting in elevated lactate production due to a reduction in cerebral blood flow (CBF). The elevated tissue lactate is released into the central circulation upon resumption of normal CBF (after the termination of centrifuge run). Therefore, the observed decrease in lactate concentration during the run may result from a lag in the release of tissue lactate into the blood due to a reduction in CBF. It is speculated that at high +6 Gz, G-LOC may occur as a protective response to reduce the brain metabolic rate, to maintain energy levels and to prevent severe cellular acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Extreme hypercapnia in a fully alert patient

A patient is described with decompensated chronic obstructive lung disease (COLD) and extreme hypercapnia. Despite an arterial CO2 level of 160 mm Hg, the patient remained awake and alert. This indicates that CO2 narcosis is not an invariable finding in severe hypercapnia.

High calcitonin levels in unconscious polytrauma patients

We measured levels of calcitonin and other markers of calcium and phosphorus metabolism in both unconscious and conscious patients after multiple trauma. We found dramatic increases in calcitonin levels in unconscious patients, and smaller increases in conscious patients. In two cases, very high levels, more than 100 x normal, appeared to be related to more rapid healing of bone. Calcitonin levels were highest immediately after admission and decreased over the ensuing two weeks. The possible relationship between unconsciousness and the increased rate of healing of fractures is discussed.

Predicting severity of tricyclic antidepressant overdose

The measurement of plasma concentration, a prolonged QRS interval, and level of consciousness have all been recommended as useful indicators of toxicity following tricyclic antidepressant overdose. The aims of this study were firstly, to determine the relative prognostic value of each of these indicators and secondly, to assess when a patient can be discharged safely from the intensive care unit. Data were evaluated on 67 patients with tricyclic antidepressant overdose from four centers. Plasma tricyclic antidepressant concentrations were measured, coma grade was evaluated using the Matthew-Lawson Coma Scale and a ECG was obtained from 23 patients on admission. Complications such as convulsions, hypotension, arrhythmias, and need for intubation and ventilation were recorded. Thirty patients developed complications and no patient died. Coma grade was the best predictor of outcome. The development of serious complications is unlikely in patients whose level of consciousness is grade II or less and who are admitted to hospital more than 6 h after overdose. Plasma tricyclic antidepressant concentration was of no additional value in predicting toxic complications or deciding when the patient could leave the intensive care unit. Our study suggests that an alert and orientated patient with a QRS duration less than 100 ms is the best indicator for safe transfer to a medical or psychiatric ward.

Delayed hyperbaric oxygen therapy for carbon monoxide intoxication--two case reports

The severity of signs and symptoms following carbon monoxide intoxication often does not relate to admission carboxyhaemoglobin levels. Two cases are presented with severe neurological impairment despite carboxyhaemoglobin levels of 2% and 1.7% on admission to hospital, who responded well to hyperbaric oxygen therapy. In one case, symptoms recurred several days later, but responded to further hyperbaric oxygen therapy. The role of and possible mechanism of action of late hyperbaric oxygen treatment in carbon monoxide intoxication are discussed.

Arterial blood gases in patients with acute head injury at the accident site and upon hospital admission

Prior to the start of supportive therapy at the site of the accident, arterial blood samples from 47 patients with acute head injury were taken for blood gas analysis. At the same time, the degree of unconsciousness was assessed using the Glasgow-Coma-Scale. After transport to the hospital, arterial blood gases and the level of unconsciousness were again determined. A very close correlation was found between the initial depth of unconsciousness and the degree of hypercapnia (R = -0.90). Patients with head injury and other multiple injuries did not differ in this report (R = -0.95) from those with isolated head injury. The correlation between PaO2 and the degree of unconsciousness was less well defined, and the results showed a greater degree of scatter (R = 0.54). The acidosis observed resulted mainly from the rise in PaCO2. The absence of any correlation between the base excess and the Glasgow-Coma-Scale levels (R = -0.27) makes a common metabolic derangement unlikely. As a result of intubation and controlled ventilation, the hypercapnia of the comatose patients had been corrected, and a correlation could no longer be found between the Glasgow-Coma-Scale level and the PaCO2. In order to avoid hypoventilation, which carries with it the danger of a rise in intracranial pressure, all patients with severe head injury should be intubated and ventilated as soon as possible after the accident.

CO2 retention with minimal symptoms but severe dysfunction during wet simulated dives to 6.8 atm abs

During wet dives in a hyperbaric chamber to 6.8 atm abs (690 kPa), air breathing subjects were experimentally exposed to external breathing resistance. Two of them were, unbeknownst to themselves, severely incapacitated. In the first incident the subject had been exercising for 25 min (end-tidal PCO2 60-65 mmHg, 7.3-8.0 kPa) when the breathing resistance was rapidly increased from low to very high (requiring pressure swings of 80 cmH2O, 8 kPa, peak to peak). He functioned normally (end-tidal PCO2 72 mmHg, 9.6 kPa) for about 100 s but 20 s later he was confused and irrational. After being extracted from the water (end-tidal PCO2 above 90 mmHg, 12 kPa), he lost consciousness for about 60 s. In the second incident the subject was exercising and breathing against a high resistance (pressure swings of 50-55 cmH2O, 5.0-5.6 kPa). His end-tidal PCO2 was high (65-68 mmHg, 8.7-9.3 kPa) throughout the exercise period, and after 24 min he reported mild dyspnea. A few seconds later he became confused. In other experiments both subjects voluntarily terminated experiments when the breathing resistance became overwhelming. These 2 subjects generally had high end-tidal PCO2 levels, but 1 other subject with end-tidal PCO2 levels in the same range never experienced any problems. These incidents indicate that severe hypercapnia does not necessarily correlate with dyspnea and that severe disturbances in mental function due to hypercapnia can develop suddenly when high breathing resistance is encountered in diving.

Trial of normobaric and hyperbaric oxygen for acute carbon monoxide intoxication

The value of hyperbaric oxygen in the treatment of acute carbon monoxide intoxication was assessed in 629 adults who had been poisoned at home in the 12 h before admission to hospital. In patients without initial impairment of consciousness (group A) the effect of 6 h of normobaric oxygen (NBO) (group A0, n = 170) was compared with that of 2 h of hyperbaric oxygen (HBO) at 2 atmospheres absolute (ATA) plus 4 h NBO (group A1, n = 173). At the 1 month follow-up 66% of A0 and 68% of A1 patients had recovered. In patients with initial impairment of consciousness the effect of one session of HBO (group B1, n = 145) was compared with that of two sessions (group B2, n = 141); all group B patients also received 4 h of NBO. At 1 month of follow-up 54% group B1 and 52% group B2 patients had recovered. The 7 patients left with neuropsychiatric sequelae (3 B1, 4 B2) and the 4 who died (2 B1, 2 B2) had all presented with coma. HBO was not useful in patients who did not lose consciousness during carbon monoxide intoxication, irrespective of their carboxyhaemoglobin level, nor were two sessions of HBO in patients who sustained only a brief loss of consciousness. The prognosis is poorest for those presenting with coma; the trial needs to be pursued in this group of patients until the power of the study is sufficient to demonstrate the value or otherwise of HBO.

Complications and protocol considerations in carbon monoxide-poisoned patients who require hyperbaric oxygen therapy: report from a ten-year experience

We conducted a study to determine the type, incidence, and timing of complications that occur in patients who have a carbon monoxide (CO) exposure serious enough to require hyperbaric oxygen therapy (HBOT). Complication data were retrospectively collected from a ten-year period for 297 consecutive CO-poisoned emergency department patients who received HBOT. HBOT was indicated for 41% of the patients because of an elevated carboxyhemoglobin (COHb) level alone. Central nervous system dysfunction, including loss of consciousness, and/or cardiovascular dysfunction, was the criteria for HBOT in 59% of patients, regardless of their COHb level. The mean peak COHb level was 38 mg%, with 88% of patients having a peak COHb level greater than 25 mg%. The mortality rate was 6% in this case series. Cardiac arrest occurred in 8% of patients; all experienced their first arrest prior to HBOT. The 3% of patients who sustained an isolated respiratory arrest and those who had a myocardial infarction did so prior to HBOT. Several complications, however, occurred for the first time or as a recurrent event during HBOT. These included emesis (6%), seizures (5%), agitation requiring restraints or sedation (2%), cardiac dysrhythmias or arrests (2%), and arterial hypotension (2%). No patient's level of consciousness deteriorated subsequent to the initial resuscitation except for those who later had a generalized seizure. The most significant complication attributable to HBOT was tension pneumothorax, noted in three patients (1%).(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of oxygen therapy devices used in the postoperative recovery period

Seventy-one patients scheduled to undergo upper or lower abdominal surgical procedures were allocated at random to one of seven treatment groups: in the recovery room they were to receive oxygen via a 40% Ventimask with 10 litres/minute oxygen flow, or via either a Hudson mask or a nasal cannula with 3, 6 or 9 litres/minute oxygen flow. The 40% Ventimask gave the most consistent, satisfactory postoperative values of PaO2 but the much cheaper nasal cannula at 6 or 9 litres/minute was generally adequate in conscious patients. The performance of the intermediately priced Hudson mask was similar to that of the nasal cannula at these flows. The unconscious state was associated with a 45% lower PaO2 than the rousable or awake states. Differences between the treatments with regard to postoperative PaCO2 were small and non-significant. The nasal cannula with 6 litres/minute humidified oxygen flow is recommended for routine treatment, and the Ventimask for unconscious patients.

[A new method to estimate blood alcohol concentration from the breath of unconscious subjects (author's transl)]

The method of rebreathing and its particular importance to the estimation of blood alcohol concentration (BAC) are described. A face mask with an accompanying valve chamber to which a collection bag was attached proved to meet the requirements arising from the physiological exchange processes in rebreathed air. Practical tests in the laboratory revealed excellent agreement between the values obtained by direct measurements of breath alcohol by means of an IR-Spectrophotometer and those from stored samples. The application of the method described is of particular importance in cases of unconscious and benumbed patients, of sleeping and uncooperative patients and those with collapsed veins suspected of heavy alcohol intoxication. It has been proven to be an essential aid in differential diagnosis since it allows instantaneous determination and continuous monitoring of the BAC-level which aids in the observation of the reduction of this level. This was demonstrated in practice with 9 patients at the alcohol emergency clinic in Mainz on the carnival "Rosenmontag".

Significance of hyperlactatemia in acute hypnotic drug poisoning

Lactate concentration, fibrinogen and fibrin(ogen) -- degradation-products in central venous blood were analysed in 35 unconscious patient with acute hypnotic drug poisoning (HDP) and compared with the results in 13 healthy control persons undergoing the same degree of forced diuresis via central venous catheters. Blood samples were taken on admission and at 12 h intervals up to 36 h after admission. Patients with HDP were attributed to the categories of moderate intoxications (n = 17) and severe intoxications (n = 18) according to their clinical condition. On admission, blood lactate was significantly higher in severe intoxication (3.90 +/- 2.94 mmol/l) as compared to the control group (1.25 +/- 0.17 mmol/l). Blood lactate was less elevated in moderate poisoning (2.74 +/- 1.22 mmol/l). Thirty-six hours after admission blood lactate was completely normalised in patients with moderate intoxication (1.19 +/- 0.69 mmol/l) but still significantly elevated in severely poisoned patients (2.26 +/- 1.48 mmol/l). Lactate concentration was above normal in 15 out of 17 patients with moderate and in 17 out of 18 patients with severe poisoning. A statistically significant linear correlation existed between the duration of unconsciousness and the maximal lactate concentration within 12 hrs after admission. For fibrinogen concentrations statistically significant differences were observed neither between groups nor across time. Titers of FDP were elevated in 9 out of 11 patients with moderate and to a higher degree in all patients with severe poisoning, indicating low rate DIC. Hyperlactatemia is a frequent finding in acute hypnotic drug poisoning. Blood lactate estimations may improve the evaluation of the severity of poisoning and the efficacy of therapeutic interventions.

Serum cortisol abnormalities after craniocerebral trauma

Serial estimations of serum cortisol were performed in 49 patients with craniocerebral trauma. Abnormalities of serum cortisol, including alterations in diurnal rhythm and elevations of serum cortisol level, occurred in 21 patients. The frequency and severity of the abnormalities correlated with the severity of the head injury, and there was a trend suggesting that middle fossa basal skull fractures predisposed to cortisol abnormalities. A further 6 patients were studied to assess the effects of exogenous dexamethasone, and in all patients there was suppression of elevated serum cortisol levels by the dexamethasone. The findings suggest that hypercortisolemia after head injury is related to an alteration rather than an abolition of the normal feedback mechanism. (Neurosurgery, 5: 559--565, 1979).

Alterations of the basal serum insulin and blood glucose in brain-injured patients

Serial fasting blood glucose and basal serum insulin were measured in brain-injured patients. The endocrine changes were compared with the level of consciousness. Evaluating the serial examinations of 92 brain-injured and 31 control patients we came to the following conclusions. There is a quantitative correlation between the alterations in the level of consciousness and the fasting blood-glucose and serum-insulin levels in brain-injured patients. Deep coma is connected with a high blood-sugar level, clear consciousness with a normal glucose level. The insulin level is, however, decreased in the comatose state and normal in the state of clear consciousness. According to the alterations in blood-glucose and insulin levels, brain-injured patients can be divided into four groups. The alterations in the insulin level cannot give a proper explanation of the blood-sugar changes. Some changes in the levels of both blood glucose and serum insulin may have prognostic significance. According to our results it can be supposed that certain cerebral structures take part in the regulation of the basal insulin secretion.