Bispectral index system (BIS) monitoring reduces time to extubation and discharge in children requiring oral presedation and general anesthesia for outpatient dental rehabilitation

PURPOSE

Pediatric oral rehabilitation patients who receive presedation with oral Versed and general anesthesia (GA) occasionally experience prolonged sedation and delayed discharge. The Bispectral Index System (BIS) is an EEG monitor that measures the anesthesia level. The purpose of this study was to compare the effects of monitoring the BIS to not monitoring the BIS on time from discontinuation of GA to extubation and to discharge.

METHODS

Twenty-nine children were enrolled. BIS was monitored from admission until discharge. Each child received 0.7 mg/kg of oral Versed. In the operating room, GA with sevoflurane (IH), rocuronium 1 mg/kg (IV), fentanyl 1 microg/kg (IV), and ondansetron 0.15 mg/kg (IV) was administered. Randomly, in half the patients, the anesthesiologist maintained the level of anesthesia and BIS by adjusting sevoflurane. In the rest, the anesthesiologist did not know BIS. The time from turning off sevoflurane to discharge was compared.

RESULTS

Group 1 patients were extubated 5+/-2 minutes sooner than group 2 patients (P=.04). The post-anesthesia care unit stay for group 1 patients was 47+/-17 minutes compared to 63+/-17 minutes in group 2. (p=0.02).

CONCLUSIONS

Monitoring anesthesia with BIS promotes earlier extubation and discharge for pediatric dental patients who receive oral Versed and sevoflurane GA.

Bispectral Index System (BIS) monitoring reduces time to discharge in children requiring intramuscular sedation and general anesthesia for outpatient dental rehabilitation

PURPOSE

Pediatric patients who receive both intramuscular (i.m.) sedation and general anesthesia (GA) for oral rehabilitation occasionally experience prolonged sedation and delayed discharge. The Bispectral Index System (BIS) is an EEG monitor that measures the level of sedation. The authors compared discharge times of patients who had BIS monitoring to those who did not to determine if the use of BIS speeded discharge.

METHODS

After IRB approval, 20 children were enrolled. BIS was monitored continuously from admission until discharge. Each child received ketamine, midazolam, and glycopyrrolate i.m. Once sedated, the patient was transferred to the operating room, monitored, and i.v. access was established. GA proceeded with sevoflurane, rocuronium, and fentanyl. Randomly, in half the patients, the anesthesiologist knew and maintained the BIS at GA level of sedation by adjusting sevoflurane. In the rest, the anesthesiologist did not know BIS. Time from turning of sevoflurane to discharge was noted and compared.

RESULTS

Patients where the BIS was known and used were discharged 60+/-13 minutes after the end of GA. Patients where BIS was unknown were discharged 90+/-11 minutes after the end of GA (P<.001).

CONCLUSIONS

Based on the data, the authors recommend the use of BIS to facilitate faster discharge of pediatric patients who require i.m. sedation and GA for oral rehabilitation.

Influence of the glia limitans on pial arteriolar relaxation in the rat

We examined whether damage to the glia limitans (GL), via exposure to the gliotoxin l-alpha-aminoadipic acid (l-alphaAAA), alters hypercapnia-induced pial arteriolar dilation in vivo. Anesthetized female rats were prepared with closed cranial windows. Pial arteriolar diameters were measured using intravital microscopy. l-alphaAAA (2 mM) was injected into the space under the cranial windows 24 h before the study, and injury to the GL was confirmed by light microscopy. l-alphaAAA was associated with a reduction in pial arteriolar CO(2) reactivity to 40-50% of the level seen in vehicle-treated controls, with no further reduction in the CO(2) response after nitric oxide (NO) synthase (NOS) inhibition via N(omega)-nitro-l-arginine (l-NNA). Subsequent blockade of prostanoid synthesis, via indomethacin (Indo), reduced CO(2) reactivity to 10-15% of normal. In vehicle-treated controls, l-NNA, followed by Indo, reduced the response to approximately 50% and then to 15-20% of the normocapnic value, respectively. On the other hand, l-alphaAAA had no effect on vascular responses to the endothelium-dependent vasodilator acetylcholine or the NO donor SNAP and did not alter cortical somatosensory evoked responses. This indicates an absence of any direct l-alphaAAA actions on pial arterioles or influence on neuronal transmission. Furthermore, l-alphaAAA did not alter the vasodilation elicited by topical application of an acidic artificial cerebrospinal fluid solution, suggesting that the GL influences the pial arteriolar relaxation elicited by hypercapnic, but not local extracellular (EC), acidosis. That differences exist in the mechanisms mediating hypercapnia- versus EC acidosis-induced pial arteriolar dilations was further exemplified by the finding that topical application of a neuronal NOS (nNOS)-selective blocker (ARR-17477) reduced the response to hypercapnia (by approximately 65%) but not the response to EC acidosis. Disruption of GL gap junctional communication, using an antisense oligodeoxynucleotide (ODN) connexin43 knockdown approach, was accompanied by a 33% lower CO(2) reactivity versus missense ODN-treated controls. These results suggest that the GL contribution to the hypercapnic vascular response appears to involve the NO-dependent component rather than the prostanoid-dependent component and may involve gap junctional communication. We speculate that the GL may act to facilitate the spread, to pial vessels, of hypercapnia-induced vasodilating signals arising in the comparatively few scattered nNOS neurons that lie well beneath the GL.

Agonist-specific differences in mechanisms mediating eNOS-dependent pial arteriolar dilation in rats

Nitric oxide (NO), derived from the endothelial isoform of NO synthase (eNOS), is a vital mediator of cerebral vasodilation. In the present study, we addressed the issue of whether the mechanisms responsible for agonist-induced eNOS activation differ according to the specific receptor being stimulated. Thus we examined whether heat shock protein 90 (HSP90), phosphatidylinositol-3-kinase (PI3K), and tyrosine kinase participate in ACh- versus ADP-induced eNOS activation in cerebral arterioles in vivo. Pial arteriolar diameter changes in anesthetized male rats were measured during sequential applications of ACh and ADP in the absence and presence of the nonselective NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME), the neuronal NOS (nNOS)-selective inhibitor ARR-17477, the HSP90 blocker 17-(allylamino)-17-demethoxygeldanamycin (AAG), the PI3K inhibitor wortmannin (Wort), or the tyrosine kinase blocker tyrphostin 47 (T-47). Only NOS inhibition with L-NAME (not ARR-17477) reduced ACh and ADP responses (by 65-75%), which suggests that all of the NO dependence in the vasodilating actions of those agonists derived from eNOS. Suffusions of AAG, Wort, and T-47 were accompanied by substantial reductions in ACh-induced dilations but no changes in the responses to ADP. These findings suggest that muscarinic (ACh) and purinergic (ADP) receptor-mediated eNOS activation in cerebral arterioles involve distinctly different signal transduction pathways.

Chronic estrogen depletion alters adenosine diphosphate-induced pial arteriolar dilation in female rats

We examined pial arteriolar reactivity to a partially endothelial nitric oxide synthase (eNOS)-dependent vasodilator ADP as a function of chronic estrogen status. The eNOS-dependent portion of the ADP response was ascertained by comparing ADP-induced pial arteriolar dilations before and after suffusion of a NOS inhibitor, N(omega)-nitro-L-arginine (L-NNA; 1 mM) in intact, ovariectomized (Ovx), and 17beta-estradiol (E2)-treated Ovx females. We also examined whether ovariectomy altered the participation of other factors in the ADP response. Those factors were the following: 1) the prostanoid indomethacin (Indo); 2) the Ca2+-dependent K+ (K(Ca)) channel, iberiotoxin (IbTX); 3) the ATP-regulated K+ (K(ATP)) channel glibenclamide (Glib); 4) the K(Ca)-regulating epoxygenase pathway miconazole (Mic); and 5) the adenosine receptor 8-sulfophenyltheophylline (8-SPT). In intact females, the eNOS-dependent (L-NNA sensitive) portion of the ADP response represented approximately 50% of the total. The ADP response was retained in the Ovx rats but L-NNA sensitivity disappeared. On E2 replacement, the initial pattern was restored. ADP reactivity was unaffected by Indo, Glib, Mic, and 8-SPT. IbTX was associated with 50-80% reductions in the response to ADP in the intact group that was nonadditive with L-NNA, and 60-100% reductions in the Ovx group. The present findings suggest that estrogen influences the mechanisms responsible for ADP-induced vasodilation. The continued sensitivity to IbTX in Ovx rats, despite the loss of a NO contribution, is suggestive of a conversion to a hyperpolarizing factor dependency in the absence of E2.

Sodium nitroprusside compared with isoflurane-induced hypotension: the effects on brain oxygenation and arteriovenous shunting

We compared sodium nitroprusside (SNP)-induced hypotension with 3% isoflurane-induced hypotension with regard to brain tissue oxygen pressure (PtO(2)), middle cerebral artery (MCA) blood flow, and cerebral arteriovenous shunting. Eight dogs were anesthetized with 1.5% isoflurane. After a craniotomy, a probe was inserted into the left frontoparietal brain cortex to mea-sure tissue gases and pH. Blood flow was measured in a secondary branch of the MCA by a flowprobe. Measurements were made during baseline 1.5% isoflurane, during 1.5% isoflurane and SNP-induced hypotension or 3% isoflurane-induced hypotension to a mean pressure of 60-65 mm Hg, and during continued treatment with SNP or 3% isoflurane with blood pressure support to baseline levels with phenylephrine. Shunting was calculated from arterial, sagittal sinus, and tissue (indicating capillary) oxygen content. During hypotension with SNP, PtO(2) decreased 50%, and shunting increased 50%. During hypotension with 3% isoflurane, PtO(2) and shunting did not change. Blood pressure support increased PtO(2) and MCA flow during both SNP and 3% isoflurane treatment. These results show that SNP is a cerebrovasodilator but that hypotension will decrease PtO(2), probably because of an increase in arteriovenous shunting and a decrease in capillary perfusion.

IMPLICATIONS

We measured brain arteriovenous shunting and tissue oxygen pressure(PtO(2))during a 40% decrease in blood pressure induced by sodium nitroprusside (SNP)or 3% isoflurane. Large-dose isoflurane maintainedPtO(2) with no change in shunting. SNP infusion decreasedPtO(2) 50%and increased shunting 50%. This suggests that SNP-induced hypotension decreases PtO(2) because of a decrease in capillary perfusion.

beta-Adrenoceptor and nNOS-derived NO interactions modulate hypoglycemic pial arteriolar dilation in rats

We examined the relative contributions from nitric oxide (NO) and catecholaminergic pathways in promoting cerebral arteriolar dilation during hypoglycemia (plasma glucose congruent with 1.4 mM). To that end, we monitored the effects of beta-adrenoceptor (beta-AR) blockade with propranolol (Pro, 1.5 mg/kg iv), neuronal nitric oxide synthase (nNOS) inhibition with 7-nitroindazole (7-NI, 40 mg/kg ip) or ARR-17477 (300 microM, via topical application), or combined intravenous Pro + 7-NI or ARR-17477 on pial arteriolar diameter changes in anesthetized rats subjected to insulin-induced hypoglycemia. Additional experiments, employing topically applied TTX (1 microM), addressed the possibility that the pial arteriolar response to hypoglycemia required neuronal transmission. Separately, Pro and 7-NI elicited modest but statistically insignificant 10-20% reductions in the normal ~40% increase in arteriolar diameter accompanying hypoglycemia. However, combined Pro-7-NI was accompanied by a >80% reduction in the hypoglycemia-induced dilation. On the other hand, the combination of intravenous Pro and topical ARR-17477 did not affect the hypoglycemia response. In the presence of TTX, the pial arteriolar response to hypoglycemia was lost completely. These results suggest that 1) beta-ARs and nNOS-derived NO interact in contributing to hypoglycemia-induced pial arteriolar dilation; 2) the interaction does not occur in the vicinity of the arteriole; and 3) the vasodilating signal is transmitted via a neuronal pathway.

Effects of estrogen on leukocyte adhesion after transient forebrain ischemia

BACKGROUND AND PURPOSE

Recent findings indicate that estrogen (ie, 17beta-estradiol [E(2)]) provides neuroprotection in models of transient global and focal ischemia. Enhanced postischemic leukocyte adhesion and infiltration have been linked to neuropathology in the brain as well as other tissues. We recently showed that estrogen reduces leukocyte adhesion in the cerebral circulation of female rats during resting conditions.

METHODS

We compared leukocyte adhesion in pial venules in vivo in intact, ovariectomized (OVX), and E(2)-treated OVX female rats subjected to transient forebrain ischemia (30-minute right common carotid artery occlusion and hemorrhagic hypotension) and reperfusion. Adherent rhodamine-6G-labeled leukocytes were viewed through a closed cranial window with the use of intravital microscopy. Leukocyte adhesion was measured before ischemia and at different times after reperfusion.

RESULTS

Before ischemia, leukocyte adhesion (measured as a percentage of venular area occupied by adherent leukocytes) was 2 to 3 times greater in OVX versus intact or E(2)-treated OVX rats (7.0%, 3.4%, and 2.2%, respectively). This difference disappeared at 120 minutes of reperfusion, when comparable levels of enhanced leukocyte adhesion were observed in all groups. In OVX rats, leukocyte adhesion remained elevated after 4 and 6 hours of reperfusion (11.6% and 12.9%, respectively), while the other 2 groups showed significantly lower levels (5.0% and 5.8% for intact rats and 7.0% and 7.2% for E(2)-treated OVX rats).

CONCLUSIONS

Present results demonstrate that estrogen modulates leukocyte adhesion in the cerebral circulation after transient forebrain ischemia. This effect suggests that decreased leukocyte adhesion may be an important mechanism in estrogen-mediated neuroprotection.

The effect of anticonvulsant therapy on two doses of rocuronium-induced neuromuscular blockade

Larger and more frequent doses of steroidal neuromuscular blocking agents are required to paralyze patients taking anticonvulsants (carbamazepine and phenytoin). We compared the effects of rocuronium on onset, duration, and speed of recovery from neuromuscular blockade (NMB) in anticonvulsant-treated (Tx) and untreated (C or control) patients. Thirty-eight neurosurgical patients were enrolled: 11 Tx and 8 C patients received 0.6 mg/kg rocuronium; 9 Tx and 10 C patients received 1.2 mg/kg rocuronium. Anesthesia was induced with midazolam, fentanyl, and thiopental, and maintained with N2O and isoflurane in O2. The evoked compound electromyograph (EMG) of the hypothenar eminence was recorded (train-of-four supramaximal stimulus at 2 Hz every 20 seconds). Rocuronium was administered after baseline EMG was recorded. Data = mean +/- SD. Rocuronium 1.2 mg/kg significantly shortened onset time [depression of baseline height of first twitch (T1) to 10% of baseline] of NMB versus rocuronium 0.6 mg/kg in both Tx (2.5+/-2 versus 3.3+/-2 minutes) and C (1.3+/-1 versus 2.8+/-1 minute) patients. Duration (recovery to 25% of T1) of NMB was significantly shorter in the Tx patients than in the C patients who received rocuronium 0.6 mg/kg (21+/-9 versus 45+/-20 minutes), but similar in Tx and C patients who received 1.2 mg/kg rocuronium (56+/-24 versus 69+/-21 minutes). The speed of recovery (time from 10 to 25% recovery of T1) was significantly slower in Tx patients who received 1.2 mg/kg rocuronium (9+/-5 minutes) than in those who received 0.6 mg/kg (5+/-3 minutes) and not different from controls who received 0.6 (9+/-4 minutes) or 1.2 mg/kg (12+/-7 minutes) rocuronium. We recommend the use of rocuronium 1.2 mg/kg and very frequent monitoring of NMB in anticonvulsant-treated patients to avoid premature and extremely rapid recovery after the standard 0.6 mg/kg rocuronium.

Painless intravenous catheterization by intradermal jet injection of lidocaine: a randomized trial

STUDY OBJECTIVE

To compare efficacy and cost of lidocaine cutaneous anesthesia by two jet injectors to routine needle infiltration for pain relief of intravenous (i.v.) catheterization, hypothesizing that jet injection of lidocaine is less painful than its needle infiltration.

DESIGN

Randomized, prospective, controlled trial.

SETTING

University hospital outpatient surgical unit.

PARTICIPANTS

75 surgical patients ASA I and II.

INTERVENTIONS

Three groups of 25 patients each were given intradermal lidocaine anesthesia via conventional 25-gauge needle/syringe; by MedEJet or Biojector jet injector prior to IV catheterization with an 18-gauge Jelco catheter.

MEASUREMENTS AND MAIN RESULTS

Visual analogue pain scores (VAS) (0 = no pain, 10 = intolerable pain) and subjective pain intensity scores (PIS) (0 = not painful, 4 = intolerable pain) at lidocaine application and at i.v. catheterization, were recorded. Cost assessment of each method was made. At local anesthetic application, no pain by proportion of VAS = 0 with MedEJet: 25/25 (confidence interval [CI]: 0.868, 0.999) and Biojector: 24/25 (CI 0.804, 0.991) was noted, but-22 of 25 patients experienced pain with needle administration: (with VAS = 0; 3/25 [CI: 0.044, 0.302]) (posterior probability [PP] > 0.999). The corresponding VAS scores (means +/- SD) were 0.00 +/- 0.00, 0.04 +/- 0.20, and 2.4 +/- 2.23 (p < 0.001). No pain by proportion of PIS = 0 with MedEJet: 25/25 (CI: 0.868, 0.999 and Biojector: 23/25 (0.749, 0.976) was noted, but pain in 20/25 was felt with the needle: 5/25 (CI: 0.090, 0.394) (PP > 0.999). The corresponding PIS scores were 0.00 +/- 0.00, 0.16 +/- 0.55, and 1.24 +/- 1.00 (p < 0.001). At i.v. catheterization, no pain by proportion of VAS = 0 with MedEJet: 22/25 (CI: 0.698, 0.956) or Biojector: 21/25 (CI: 0.651, 0.934) was noted; but pain in 19/25 with needle administration was experienced: 6/25 (CI: 0.116, 0.436) (PP > 0.999). The corresponding scores were 0.12 +/- 0.33, 0.44 +/- 0.20, and 1.64 +/- 1.50 (p < 0.001). No pain by proportion of PIS = 0 with MedEJet: 24/25 (CI: 0.804, 0.991) or Biojector: 24/25 (CI: 0.804, 0.991) was noted, but pain was apparent in 12/25 with needle administration: 13/25 (CI: 0.334, 0.701) (PP > 0.999). The corresponding scores were 0.00 +/- 0.00, 0.00 +/- 0.00, and 0.76 +/- 0.88 (p < 0.001). Cost per application: MedEJet = $0.13; needle/syringe = $0.50; Biojector = $0.94.

CONCLUSIONS

Almost completely painless i.v. catheterization was carried out by jet injection of lidocaine, but needle infiltration produced discomfort or pain and did not significantly reduce discomfort or pain at the i.v. needle insertion.

V. A new route, jet injection of lidocaine for skin wheal for painless intravenous catheterization

OBJECTIVE

The objective of this study was to compare the efficacy of intradermal lidocaine anesthesia by two jet injectors to the routine needle infiltration and to the topical EMLA cream.

SUBJECTS AND METHODS

In a randomized, prospective, controlled trial, 100 consenting surgicenter patients in a university hospital setting were divided into four groups (n = 25, each); intradermal lidocaine anesthesia was given either by the conventional 25 g needle/syringe or the Med-E-Jet or Biojector injector or EMLA cream was applied on the skin. Visual analogue pain scores (VAS) or verbal pain intensity scores (PIS) were reported by the patients at lidocaine application and i.v. catheterization. Cost was also assessed.

RESULTS

At lidocaine application, no pain was reported, since proportions of VAS = 0 were 25/25 (CI: 0.868, 0.999) with Med-E-Jet; 24/25 (0.804, 0.991) with Biojector; 25/25 (0.868, 0.999) with EMLA; in contrast to pain, 3/25 (0.044, 0.302) with the needle (PP > 0.999). The VAS scores (mean +/- SD) were 0.00 +/- 0.00, 0.04 +/- 0.20, 0.00 +/- 0.00, and 2.4 +/- 2.2 respectively (p < 0.00 1). No pain was reported by proportions of PIS = 0 with Med-E-Jet: 25/25 (CI: 0.868, 0.999); with Biojector: 23/25 (0.749, 0.976); EMLA 25/25 (0,868, 0.999); but pain with the needle: 5/25 (0.090, 0.394) (PP > 0.999). The mean +/- SD PIS scores were 0.00 +/- 0.00, 0.16 +/- 0.55, 0.00 +/- 0.00, and 1.24 +/- 1.00, respectively (p < 0.001). At i.v. catheterization, the proportions of VAS = 0 scores were 22/25 with Med-E-Jet (0.698, 0.956); 21/25 (0.651, 0.934) with Biojector; but some pain with needle: 6/25 (0.116, 0.436) (PP > 0.999). The mean +/- SD VAS scores were: 0.12 +/- 0.33, 0.44 +/- 0.20, and 1.64 +/- 1.50, respectively (p < 0.001). No pain was reported by PIS = 0 scores in 24/25 (0.804, 0.991) with Med-E-Jet; 24/25 (0.804, 0.991) with the Biojector; but pain by zero PIS scores 13/25 (0.334, 0.703) in half of the patients in the needle group (PP > 0.999). The mean +/- SD scores were 0.00 +/- 0.00, 0.00 +/- 0.00, and 0.76 +/- 0.88, respectively (p < 0.001). The EMLA cream was not evaluated because of inadequate duration of application prior to anesthetic induction. Cost/application were: Med-E-Jet = $ 0.13; needle = $ 0.50; Biojector = $ 0.94 and EMLA = $ 3.76.

CONCLUSION

Almost completely painless i.v. catheterization by jet injection of lidocaine was accomplished, while needle infiltration produced pain/discomfort and did not significantly reduce it at the i.v. needle insertion.

Role of nitric oxide, adenosine, N-methyl-D-aspartate receptors, and neuronal activation in hypoxia-induced pial arteriolar dilation in rats

In this study, we tested the hypothesis that nitric oxide (NO) and adenosine (ADO) are the principal mediators of severe hypoxia-induced vasodilation. In addition, we examined whether activation of N-methyl-D-aspartate (NMDA) receptors and/or perivascular nerves plays a role. A closed cranial window and intravital microscopy system was used to monitor diameter changes in pial arterioles (approximately 40 microns) in anesthetized rats. The relative contributions of ADO, NMDA, NO, and neuronal activation to hypoxic cerebrovasodilation were assessed using the blockers 8-sulfophenyltheophylline (8-SPT), MK-801, nitro-L-arginine methylester (L-NAME), and tetrodotoxin (TTX). Two experimental series were studied. In the first, we tested the effects of NOS inhibition, via topical L-NAME (1 mM), on moderate (PaO2 approximately 46 mmHg) then severe (PaO2 approximately 34 mmHg) hypoxia-induced dilation. To confirm that L-NAME was affecting specifically NO-dependent responses, we also examined, in each experiment, the vasodilatory responses to topical applications of NOS-dependent (adenosine diphosphate (ADP); acetylcholine (ACh)) and -independent (sodium nitroprusside (SNP)) agents, in the presence of L-NAME or, in controls, the presence of D-NAME or no added analogue. In the second series, topical suffusions of ADP, ADO, and NMDA were sequentially applied, followed by 5 min exposure to severe hypoxia (PaO2 approximately 32 mmHg). Following return to normoxia, a suffusion of either 8-SPT (10 microM), MK-801 (10 microM), TTX (1 microM), or 8-SPT+MK-801 was initiated (or, in controls, application of a drug-free suffusate was maintained), and the above sequence repeated. In control, TTX, and 8-SPT+MK-801 experiments, baseline conditions were then restored and hypercapnia (PaCO2 = 70-85 mmHg) was imposed. In the series 1 control groups, moderate and severe hypoxia elicited approximately 20% and 35-40% increases in diameter, respectively. L-NAME attenuated ADP- and ACh-induced dilations, did not alter the arteriolar responses to SNP or moderate hypoxia, but prevented further dilation upon imposition of severe hypoxia. This suggested that 45-50% of the severe hypoxia response was NO-dependent. In series 2, 8-SPT blocked the adenosine response and reduced severe hypoxia-induced dilation by 46%. MK-801 predictably blocked NMDA-induced relaxation and reduced the hypoxic response by 42%. When combined, 8-SPT and MK-801 affected hypoxic vasodilation additively. After TTX, the ADP and ADO responses were normal, but NMDA and hypoxia responses were completely blocked. Hypercapnia-induced dilation was unaffected by TTX or 8-SPT+MK-801. The results imply that severe hypoxia-induced release of NO and ADO, and the accompanying pial arteriolar dilation, are wholly dependent on the capacity to generate action potentials in perivascular nerves. The similarity of the L-NAME and MK-801 effects on hypoxic cerebrovasodilation suggests that the NO-dependency, to a large degree, derives from NMDA receptor activation.

The role of neuronal nitric oxide synthase in regulation of cerebral blood flow in normocapnia and hypercapnia in rats

The nitric oxide synthase (NOS) inhibitors, nitro-L-arginine, its methyl ester, and N-monomethyl-L-arginine, have been shown to attenuate resting CBF and hypercapnia-induced cerebrovasodilation. Those agents nonspecifically inhibit the endothelial and neuronal NOS (eNOS and nNOS). In the present study, we used a novel nNOS inhibitor, 7-nitroindazole (7-NI) to examine the role of nNOS in CBF during normocapnia and hypercapnia in fentanyl/N2O-anesthetized rats. CBF was monitored using laser-Doppler flowmetry. Administration of 7-NI (80 mg kg-1 i.p.) reduced cortical brain NOS activity by 57%, the resting CBF by 19-27%, and the CBF response to hypercapnia by 60%. The 60% reduction was similar in magnitude to the CBF reductions observed in previous studies in which nonspecific NOS inhibitors were used. In the present study, 7-NI did not increase the MABP. Furthermore, the CBF response to oxotremorine, a blood-brain barrier permeant muscarinic agonist that induces cerebrovasodilation via endothelium-derived NO, was unaffected by 7-NI. These results confirmed that 7-NI does not influence eNOS; they also indicated that the effects of 7-NI on the resting CBF and on the CBF response to hypercapnia in this study were solely related to its inhibitory action on nNOS. The results further suggest that the NO synthesized by the action of nNOS participates in regulation of basal CBF and is the major, if not the only, category of NO contributing to the hypercapnic CBF response.

The role of endothelium and nitric oxide in rat pial arteriolar dilatory responses to CO2 in vivo

Using a closed cranial window system and intravital microscopy/videometry, we studied the rat pial arteriolar (30-60 microns) responses to CO2 before and following a light/dye (L/D) endothelial injury or topical application of the nitric oxide synthase (NOS) inhibitor, nitro-L-arginine (L-NA) or its inactive form, D-NA. L/D treatment consisted of intravenous injection of sodium fluorescein and the illumination (for 90 s) of arteriolar discrete segments on the cortical surface with light from a mercury lamp. Functional changes in pial arteriolar endothelium were characterized by evaluating responses to topical application of acetylcholine (Ach, 5 x 10(-4) M) and to intravenous (i.v.) oxotremorine (OXO, a stable blood-brain barrier permeant muscarinic agonist, 1 microgram kg-1 min-1). After the L/D injury, dilation to Ach was absent whereas dilations to the NO donor, S-nitrosoacetyl-penicillamine (SNAP, 10(-5) M) and to CO2 (5%) were unchanged (PaCO2 = 70 mm Hg). Loss of Ach response but intact SNAP response confirmed functional endothelial injury and intact smooth-muscle function. The global endothelium-dependent vasodilation induced by i.v. OXO was markedly attenuated when expanding the L/D injury field from 300 microns to 6 mm in diameter. However, the global vasodilation induced by inhalation of CO2 was still unaffected by this increase in the area of light exposure. This provides evidence that the expanded exposure was capable of impairing global vasodilation resulting from endothelium-dependent stimuli but not from inhalation of CO2. The intact CO2 response despite an endothelial dysfunction suggests that the reported NO dependence of hypercapnia-induced cerebral hyperemia in rats cannot be attributed to an endothelial NO source.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of nitric oxide and endothelium in rat pial vessel dilation response to isoflurane

Isoflurane induces cerebral hyperemia. We sought to assess whether isoflurane induces cerebral microvessel dilation in vivo, and if so, to determine whether nitric oxide (NO) and endothelium are involved. By using a rat closed cranial window model, pial arterioles and venules of 30-70 microns in diameter were measured using intravital microscopy. The cerebral microvascular dilatory response was recorded as percent change of diameter from baseline. The pial vessels were suffused with sodium nitroprusside (SNP) or S-nitroso-acetyl-penicillamine (SNAP) to verify intact vascular smooth muscle relaxation function, and with adenosine diphosphate (ADP) and/or acetylcholine (ACh) to verify endothelial NO-generating capability. To isolate NO's role in the cerebral microvascular effects of isoflurane (Protocol I), microvessels were studied with and without nitric oxide synthase (NOS) inhibition by topically applied nitro-L-arginine methyl ester (L-NAME). In controls, L-NAME was replaced by its inactive enantiomer, nitro-D-arginine methyl ester (D-NAME). Mercury light plus fluorescein dye (LD) endothelial injury (Protocol II) was used to delineate an endothelium-mediated mechanism. Subsequently, vasodilator applications were repeated to verify the desired effects of the interventions and followed by suffusion of isoflurane 1%, 2%, and 3% (Protocol I) or isoflurane 3% (Protocol II). Suffusions of SNP, ADP, and ACh induced diameter increases of 15%-30%. NOS inhibition with L-NAME greatly attenuated ADP and ACh responses, but did not alter the SNP response, confirming that NO generation was blocked, but not NO action. These responses were unaffected in D-NAME-suffused rats. Isoflurane dilated arterioles 17% and venules 6% in the presence of D-NAME suffusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein kinase C suppresses receptor-mediated pial arteriolar relaxation in the diabetic rat

Cerebral vasodilatory responses are selectively impaired in chronically hyperglycemic, diabetic rats. In this study, we tested the hypothesis that chronic hyperglycemia-induced protein kinase C (PKC) activation can account for the suppression of 2 separate receptor-mediated vascular relaxation processes: (1) endothelium-derived nitric oxide (NO) release, and (2) NO-independent beta-adrenergic receptor (beta-AR) activation. The in vivo reactivity of pial arterioles was evaluated in anesthetized rats (streptozotocin-treated diabetics and controls) using a closed cranial window and intravital microscopy. Compared with controls, diabetic rats showed a substantial attenuation or loss of the arteriolar relaxation response accompanying suffusion of the receptor-linked, NO-dependent agonists, acetylcholine (Ach) and adenosine diphosphate (ADP), and the beta-AR-agonist, isoproterenol (ISO). The vasodilatation induced by the direct NO donor, sodium nitroprusside (SNP), was the same in both groups. In the presence of the PKC inhibitor, staurosporine (STAURO), the Ach, ADP, and ISO responses were, largely restored and the SNP response was unaffected. STAURO produced no changes in Ach, ADP, ISO, or SNP responses in non-diabetic rats. These results suggest that PKC activation in chronically hyperglycemic, diabetic rats suppresses receptor-dependent NO release and desensitizes beta-ARs.

Halothane vasodilation and nitric oxide in rat pial vessels

We investigated whether halothane (HAL), administered via cerebral cortical suffusion at concentrations of 1, 2, and 3%, could induce cerebral microvascular dilatation in vivo and whether the vasodilatory response was dependent on nitric oxide (NO) synthesis. The studies were performed using N2O/fentanyl-anesthetized, paralyzed, and mechanically ventilated rats. A closed cranial window and an intravital microscopy technique were employed. This system permitted the controlled delivery of various vasoactive agents in an artificial cerebrospinal fluid (aCSF) solution and the measurement of diameters of pial arterioles and venules. Each experiment included evaluations of (a) the direct smooth muscle relaxing action of NO, using sodium nitroprusside (SNP), and (b) the capacity for generation and release of endogenous NO, using adenosine diphosphate (ADP). Following confirmation of an intact NO-relaxing and generating capacity, HAL (in aCSF) was suffused at increasing concentrations. Nitric oxide synthase (NOS) inhibition was established with topical nitro-L-arginine (L-NA) or its methyl ester (L-NAME) and the above sequence repeated. The results for rats treated with L-NA (n = 5) or L-NAME (n = 5) were analyzed separately and as a combined group. No significant differences in vascular responses were observed when comparing the two groups. Initially, both SNP and ADP produced significant diameter increases (all groupings) in arterioles (14-28% change) and venules (14-25% change). For all groups, suffusions of 1 to 3% HAL produced arteriolar dilation, ranging from a 10 to 25% increase over baseline diameter. A statistically significant dose dependency was only observed with the combined data.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of recombinant human erythropoietin in a Jehovah's Witness

We report the case of a Jehovah's Witness who bled massively, refused blood transfusion, and survived profound anemia (hematocrit = 5.6%) intact. The patient was treated with recombinant human erythropoietin, parenteral iron, and oxygen. The pharmacology and hematopoietic response to erythropoietin are discussed. We suggest considering this therapy for acutely anemic patients who refuse transfusion to decrease the duration of the most severe anemia.

Nitric oxide synthesis and regional cerebral blood flow responses to hypercapnia and hypoxia in the rat

The role of nitric oxide (NO) synthesis in the cerebral hyperemic responses to hypercapnia and hypoxia was investigated in anesthetized rats. Regional CBF (rCBF) measurements were obtained in the cortex (CX), subcortex (SC), brainstem (BS), and cerebellum (CE) using radiolabeled microspheres. The rCBF responses to either hypercapnia (PaCO2 = 70-80 mm Hg) or hypoxia (PaO2 = 40-45 mm Hg) were compared in rat groups studied in the presence and absence of NO synthase inhibition induced via the intravenous infusion of nitro-L-arginine methyl ester (L-NAME, 3 mg kg-1 min-1). Administration of L-NAME under normocapnic/normoxic conditions produced a 40-60% reduction in baseline rCBF values, indicating the presence of a NO "tone" in the cerebral vasculature. Infusion of L-NAME resulted in a substantial attenuation, in all regions measured, of the rCBF increases that normally accompany hypercapnia. In comparing saline-infused to L-NAME-infused rats, the percentage increases in rCBF (from normocapnic baseline values) were 351% versus 166% (CX), 446% versus 199% (SC), 443% versus 206% (BS), and 483% versus 174% (CE), respectively. The rCBF changes from baseline (delta rCBF in ml 100 g-1 min-1) were 488 versus 57 (CX), 570 versus 60 (SC), 434 versus 72 (BS), and 393 versus 45 (CE), respectively. These differences were all statistically significant (p < 0.05). During hypoxia, when compared to rats not given L-NAME, inhibition of NO synthase activity resulted in significantly greater (p < 0.05) percentage increases in rCBF (from normoxic baseline values) in most regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Erythropoiesis in infants of diabetic mothers

Neonatal polycythemia is a well-established perinatal complication in infants of diabetic mothers (IDM). To investigate the regulation of erythropoiesis in these infants, we measured cord blood erythropoietin (EP) levels by a sensitive radioimmune assay and examined the growth of erythroid progenitor colonies in a series of IDM and control infants. Fifteen of 18 diabetic mothers were managed on a protocol emphasizing careful glycemic control throughout pregnancy; 10 had glycosolated hemoglobin values within the normal, nondiabetic range during the third trimester. Cord blood EP was elevated in one of 18 IDM and in two of 13 controls (p = NS). In IDM, cord blood EP values were higher in infants delivered following maternal labor and were inversely correlated with umbilical artery pH (r = -0.72; p = 0.006). Growth of burst forming units-erythroid was similar in IDM and controls in the presence of 0.1 to 2.0 U of exogenous EP per ml of methylcellulose medium. Individual infants tended to respond consistently over the entire range of EP doses tested. The number of burst forming units-erythroid observed did not correlate with cord blood EP, birth weight, or neonatal hematocrits. We conclude that: umbilical cord blood EP levels are generally normal in IDM delivered by mothers in whom good glycemic control is maintained throughout gestation, cord blood EP values are strongly influenced by perinatal events, and the response of erythroid progenitors to EP is intrinsically normal in IDM. These data suggest that polycythemia is an adaptive response in IDM and is not associated with a primary abnormality in erythropoiesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Free erythrocyte protoporphyrin (FEP) II. The FEP test is clinically useful in classifying microcytic RBC disorders in adults

Microcytic red blood cells (RBC) are commonly encountered in clinical medicine and are caused by disorders of heme synthesis [usually iron deficiency anemia (IDA) or anemia of chronic disease (ACD)] or disorders of globin synthesis (usually thalassemia syndromes or HbE). Using the clinical history and standard laboratory tests (hematocrit, per cent saturation of transferrin (% sat), serum ferritin, Hb electrophoresis, HBA2, and HbF) we classified 198 adults with microcytic RBC as follows: 48 IDA, 11 probable IDA, 11 iron-deficient erythropoiesis without anemia, 13 ACD, 42 alpha-thalassemia trait, 35 probable alpha-thalassemia trait, 20 beta-thalassemia trait, and 15 unclassified. In addition, we demonstrated that the FEP test reliably (83-90% of the time, depending on FEP methodology) classifies microcytic RBC states into disorders of heme synthesis vs. disorders of globin synthesis. Because of reliability and ease of measurement, we recommend the hematofluorometer FEP as the first step in the clinical laboratory evaluation of microcytic RBC disorders in both adults and children.

Free erythrocyte protoporphyrin (FEP) I. Normal values for adults and evaluation of the hematofluorometer

Since the early 1970s, measurement of free erythrocyte protoporphyrin (FEP) (by microextraction or by hematofluorometer) has been widely used to screen for lead poisoning and to evaluate microcytic red blood cell (RBC) disorders in children. However, published information on normal values for FEP, performance of the hematofluorometer, and usefulness of FEP in classifying microcytic RBC disorders in adults is scant. In an adult population with normal hematocrit and MCV and normal values for serum ferritin, blood lead level, and serum bilirubin, we obtained normal hematofluorometer FEP levels of less than 30 micrograms/dL for men, and less than 40 micrograms/dL levels for women. We have evaluated a hematofluorometer against a standard microextraction procedure and feel that the hematofluorometer is superior for clinical laboratories if elevated FEPs are confirmed by retesting with washed RBC. In the second part of this paper we demonstrate the usefulness of the FEP in classifying microcytic RBC disorders in adults.

The laboratory evaluation of microcytic red blood cells

Microcytic red blood cell states are common clinical problems in both adult and pediatric age groups. The recent widespread availability of electronic blood cell counters for performing routine blood counts has increased the detection of microcytic red blood cells. Physicians must workup both symptomatic and asymptomatic patients with microcytic red blood cells before they can initiate proper therapy and/or counseling. The purpose of this review is threefold: (1) to discuss the causes of microcytic red blood cells in terms of disorders of decreased heme production vs. disorders of decreased globin production, (2) to review the clinical laboratory tests useful in differentiating microcytic red blood cell states, and (3) to present a practical approach for the laboratory workup of microcytic red blood cells.

Bone marrow and lymph node findings in a fatal case of Kawasaki's disease

Since the initial description in 1967, the clinical and laboratory features of Kawasaki's disease (KD) have been well documented. We studied a patient with KD who recovered from the acute phase of the disease, but who subsequently died at home from coronary arteritis. We describe this patient because of bone marrow and lymph node findings that have previously received little attention in the English-language literature.

Switching of the nonallelic forms of fetal hemoglobin during late gestation

The gamma chains of human fetal hemoglobin occur in two nonallelic forms, designated G gamma and A gamma, which differ from one another in having either glycine or alanine as their 136th residue respectively. In newborns, G gamma comprises about 75% of the total gamma chains, while in adults, G gamma comprises about 40% of the total gamma chains. The timing of the switching events that lead to the alteration of the rates of production of G gamma and A gamma are still unknown. Umbilical cord red blood cells from term infants were separated by density gradient fractionation into four age-dependent fractions. Red blood cell size and reticulocyte content decreased and the percent fetal hemoglobin increased with increasing gradient densities, confirming age-dependent density separation. The percent G gamma was determined by two methods on fractionated cord red blood cells to determine if the switch in the production ratio of the nonallelic forms of gamma chains began during late gestation. The G gamma content of fetal hemoglobin was found to decrease with decreasing red blood cell age, demonstrating that the switch from predominately glycine-containing gamma chains to predominately alanine-containing gamma chains begins during late gestation.

Unequal crossing-over: a common basis of single alpha-globin genes in Asians and American blacks with hemoglobin-H disease

The alpha-globin genes of five black Americans, two Chinese, and five Filipinos with HbH disease (an alpha-thalassemia state in which there is a single functional alpha gene) were analyzed by restriction endonuclease techniques. All subjects were found to have one chromosome 16, lacking both alpha genes, and another containing a single alpha gene (--/-alpha). Restriction endonuclease patterns of the DNA obtained from all 12 subjects were identical and compatible with unequal crossing-over as the mechanism of origin of the single alpha gene in these individuals.

Alpha-thalassemia in blacks is due to gene deletion

We used molecular hybridization to test if alpha-thalassemia is due to gene deletion in the black. In 10 families with clinically well-defined alpha-thalassemia-1 (alpha-thal-1), hydribization of alpha-globin cDNA was reduced to the same level as that found in Asians with alpha-thal-1, where two of the four normally present alpha-globin genes are deleted. A black child with hemoglobin H (Hb H) disease also has three globin genes deleted, as do Asian patients with Hb H disease. We conclude that alpha-thalassemia in the black is most commonly due to gene deletion.

Immune suppression of erythropoiesis in transient erythroblastopenia of childhood

Serum and IgG from four children with transient erythroblastopenia of childhood (TEC) was tested to see what effect it would have on development of erythroid colonies from bone marrow mononuclear cells. Serum and IgG specimens obtained at the time of diagnosis uniformly suppressed erythroid colony development from CFU-E. Washed bone marrow mononuclear cells from a child with TEC failed to grow in the presence of his own serum, but grew normally in the presence of isologous serum. Serum specimens obtained from patients after recovery from TEC had no effect on erythroid colony development. The anemia of TEC appears to be due to transient immune suppression of erythroid colony development.

Platelet-associated immunoglobulin G in childhood idiopathic thrombocytopenic purpura

Childhood ITP is an acquired hemorrhagic disorder with a heterogeneous clinical course. We measured PAIgG levels in 20 children with ITP (7 acute, 13 chronic). Both groups had significantly greater PAIgG values than age-matched normal subjects and thrombocytopenic controls (P less than 0.001). In addition, PAIgG values in chronic ITP were significantly lower than those in acute ITP (P less than 0.003). Serial PAIgG values were obtained in some patients; most returned to normal in association with clinical recovery. The measurement of PAIgG is useful in the diagnosis and follow-up of childhood ITP. PAIgG values may assist in differentiating acute and chronic disease in children.

Heterogeneity of fetal hemoglobin in severe alpha-thalassemia

The heterogeneity of residue 136 of the gamma-chain of human hemoglobin has been determined for a patient afflicted with severe alpha-thalassemia. Separation of the cord blood sample into the various constituent hemoglobins A, F, FI and Bart's were done on a column packed with DEAE Sephadex. The amount of glycine or alanine at position 136 was determined for hemoglobins F, FI and Bart's. The ratios determined for all three hemoglobins indicated that the G gamma/A gamma ratio is the same for all three fractions and is similar to that observed in normal cord blood samples.

Prenatal diagnosis of hemoglobin H disease

Hemoglobin H disease was diagnosed prior to the twenty-second week of gestation in a pregnancy at risk for homozygous alpha-thalassemia using the technique of DNA-DNA hybridization. Fetal DNA was obtained from amniotic fluid fibroblasts obtained during the thirteenth week of gestation and grown in culture. The fetal fibroblast DNA was hybridized to radioactive alpha-globin cDNA. The number of alpha-globin genes present in the fetus was determined by comparing results of hybridization studies on the fetal DNA to similar studies on subjects with well-defined alpha-thalassemia syndromes and with normal subjects. The diagnosis of hemoglobin H disease was confirmed at birth by studies of the cord blood. This study confirms the ability of DNA-DNA hybridization techniques to distinguish the three-gene defect of hemoglobin H disease from the lethal four-gene defect of homozygous alpha-thalassemia.

Free erythrocyte porphyrin: hemoglobin ratios, serum ferritin, and transferrin saturation levels during treatment of infants with iron-deficiency anemia

Free erythrocyte porphyrin:hemoglobin (FEP:Hb) ratios were determined on 20 infants with iron-deficiency anemia. FEB:Hb ratios were compared with simultaneously drawn serum ferritin and serum transferrin saturation levels. FEP:Hb ratios dropped steadily during treatment of the anemic infants, but remained elevated compared to age-matched nonanemic infants, until the anemia was corrected. FEP:Hb ratios detected iron deficiency when acute inflammatory disease was present. Serum ferritin levels and transferrin saturation failed to detect iron deficiency after iron therapy was started or when acute inflammatory disease was present. Measurement of FEP:Hb ratios is a reliable and practical way to make a prompt diagnosis of iron-deficiency anemia in infants.

The molecular defects of alpha-thalassemia in the Filipino

Molecular hybridization with synthetic radioactive DNA (cDNA) complementry to alpha globin mRNA sequences shows that, as in most other Southeast Asian populations, the alpha globin structural genes are deleted in Filipinos affected by the alpha-thalassemia syndromes. Thus, all 4 alpha-globin structural genes are deleted in homozygous alpha-thalassemia with hydrops fetalis, 3 and 2 structural genes are deleted in hemoglobin H disease and alpha-thalassemia-1 respectively.

Overdosage with vincristine

Five patients received overdoses of vincristine ranging from 3.5 to 32 mg. Neurotoxicity accounted for most of the complications observed. Peripheral neuropathies, cranial nerve palsies, paralytic ileus, atony of the bladder, hypertension, hypotension, seizures, inappropriate ADH secretion, and severe bone marrow depression were all encountered. Two patients died within 72 hours of the overdose. Another patient died of sepsis 22 days after the overdose. Two patients recovered and were discharged. The three patients who survived longer than a few days showed improvement in the vincristine-induced neuropathy, and the two long-term survivors had essentially complete recovery. It appears that if a patient can be supported through the critical period following an overdose, he can be expected to recover normal neurologic function.

In vitro production of platelet-binding IgG in childhood idiopathic thrombocytopenic purpura

We studied two boys, 9 and 10 years old, respectively, who underwent splenectomy eight months and six weeks after initially presenting as "typical" cases of childhood ITP. Splenic leukocytes from each child were cultured and net synthesis rates of IgG determined. Splenic synthesis rates of IgG were five-and sevenfold greater, respectively, than in spleens of control subjects. A significant portion of the splenic culture-produced IgG from each patient demonstrated specificity for homologous and autologous platelets. Synthesis rates of IgG were determined on serial cultures of bone marrow cells from the 10-year-old boy who failed to respond to splenectomy. His initial marrow synthesis rate of IgG was five times greater than mean control values. His synthesis rate of IgG in marrow decreased to the control range in association with immunosuppressive therapy and intesive platelet transfusions. These data suggest that (1) the spleen was a production site of platelet-binding IgG in the two children, and (2) the bone marrow may have been an additional site of production in our second patient.

Childhood idiopathic thrombocytopenic purpura. Aggressive management of life-threatening complications

Idiopathic thrombocytopenic purpura (ITP) in childhood is usually a benign, self-limited illness. Life-threatening complications, such as central nervous system (CNS) hemorrhage, occur in less than 1% of cases. We report a case in which the patient failed to respond to splenectomy and high-dose corticosteroid therapy. Immunosuppressive therapy with cyclophosphamide, vincristine sulfate, and corticosteroids in conjunction with frequent transfusions of platelets was associated with a complete remission that persisted after therapy was discontinued.

The micromeasurement of free erythrocyte protoporphyrin as a means of differentiating alpha thalassemia trait from iron deficiency anemia

Free erythrocyte protoporphyrin levels were measured in 29 individuals with alpha thalassemia trait, 19 with proved iron deficiency anemia, and 25 normal control subjects. Individuals with alpha thalassemia trait and normal iron studies had FEP levels in the normal range despite marked degrees of microcytosis. In contrast, individuals with iron deficiency anemia had marked elevation of FEP levels with similar degrees of microcytosis. Measurement of FEP levels appears to be a useful tool in differentiating alpha thalassemia trait from iron deficiency anemia.