Decrease In Arterial Partial Pressure Research Articles

Neurotoxic pesticides change respiratory parameters in early gill-breathing, but not in skin-breathing life-stages of zebrafish (Danio rerio)

Neurotoxic compounds can interfere with active gill ventilation in fish, which might lead to premature death in adult fish, but not in skin-breathing embryos of zebrafish, since these exclusively rely on passive diffusion across the skin. Regarding lethality, this respiratory failure syndrome (RFS) has been discussed as one of the main reasons for the higher sensitivity of adult fish in the acute fish toxicity test (AFT), if compared to embryos in the fish embryo toxicity test (FET). To further elucidate the relationship between the onset of gill respiration and death by a neurotoxic mode of action, a comparative study into oxygen consumption (MO2), breathing frequency (fv) and amplitude (fampl) was performed with 4 d old skin-breathing and 12 d old early gill-breathing zebrafish. Neurotoxic model substances with an LC50 FET/AFT ratio of > 10 were used: chlorpyrifos, permethrin, aldicarb, ziram, and fluoxetine. Exposure to hypoxia served as a positive control, whereas aniline was tested as an example of a narcotic substance interfering non-specifically with gill membranes. In 12 d old larvae, all substances caused an increase in MO2, fv and partly fampl, whereas effects were minor in 4 d old embryos. An increase of fv in 4 d old embryos following exposure to chlorpyrifos, aldicarb and hypoxia could not be correlated with an increased MO2 and might be attributed either to (1) to the successfully postponed decrease of arterial partial pressure of oxygen (PO2) through support of skin respiration by increased fv, (2) to an unspecific stimulation of the sphincter muscles at the base of the gill filaments, or (3) to the establishment of oxygen sensing for later stages. In gill-breathing 12 d old zebrafish, a concentration-dependent increase of fv was detected for aniline and chlorpyrifos, whereas for aldicarb, fluoxetine and permethrin, a decline of fv at higher substance concentrations was measured, most likely due to the onset of paralysis and/or fatigue of the gill filament sphincter muscles. Since alterations of fv serve to postpone the decrease in arterial PO2 and MO2 increased with decreasing fv, the respiratory failure syndrome could clearly be demonstrated in 12 d old zebrafish larvae. Passive respiration across the skin in zebrafish embryos could thus be confirmed as a probable reason for the lower sensitivity of early life-stages to neurotoxicants. Integration of respiratory markers into existing testing protocols with non-protected developmental stages such as embryos might help to not underestimate the toxicity of early life-stages of fish.

UNILATERAL PULMONARY ARTERY ATRESIA/AGENESIS: A CASE REPORT

A twenty-three-year-old male truck driver with a 12-pack year smoking history and no previous history of hospitalization was admitted to the “Shefqet Ndroqi” University Hospital pulmonology department after a cardiologist consultation where he was diagnosed with pulmonary hypertension. Two of the patient’s uncles from his mother’s side died during their pediatric age from congenital heart defects. A contrast-enhanced chest computed tomography was performed, and it showed an interruption of the lumen of the proximal part of the left pulmonary artery (atresia), a reduction of the left lung parenchyma volume, and bilateral pulmonary emphysema. The respiratory functional tests detected a moderate obstructive syndrome, and the 6MWT detected a decrease in arterial partial pressure of oxygen and oxygen saturation level. A diagnosis of unilateral pulmonary artery atresia/agenesis was confirmed.

Role of central irisin in the cardiorespiratory and metabolic control of adult rats

Irisin has been identified as an important exercise‐induced myokine that acts in different physiological systems; however, little is known about the participation of irisin in cardiorespiratory and basal metabolic control. Therefore, the present study evaluated the effect of intracerebroventricular (icv) injection of vehicle or irisin (IR, 0.425 µg/µL) in the fourth ventricle (4V) of adult male rats on the cardiorespiratory and metabolic control during wakefulness and sleep under room air, hypercapnia (7% CO2) and hypoxia (10% O2). Our data show a tendency of reduction in basal ventilation of IR group during wakefulness (VEH: 1056.2 ± 61.8 vs IR: 816.9 ± 30.5 mL.Kg‐1.min‐1), due to a reduction in respiratory frequency (VEH: 105.1 ± 5.3 vs IR: 85.9 ± 5.1 breaths.min‐1) and a consequent decrease in arterial partial pressure of O2 (VEH: 95.1 ± 2.4 vs IR: 88.7 ± 3.1 mmHg). No difference was observed in metabolic rate; however, central IR promoted a reduction in the air convection requirement (VEH: 57.2 ± 4.7 vs IR: 39.6 ± 3.7). Regarding the cardiovascular parameters, central injection of IR caused a significant increase in heart rate during hypoxia exposure (VEH: 342.5 ± 38.0 vs IR: 406.2 ± 16.8 beats.min‐1) without changing arterial pressure. These effects were only observed in awake conditions, with no changes evidenced during sleep. No difference in cardiorespiratory and metabolic parameter were observed under CO2 exposure after central IR injection. Therefore, our preliminary results suggest that IR caused a hypoventilation under room air conditions, possibly due to a lower ventilation, increased heart rate under hypoxic conditions, suggesting that this myokine also acts in the central nervous system to modulate breathing and cardiovascular parameters.

Efficacy analysis of the lung recruitment maneuver in correcting pulmonary atelectasis in neurological intensive care unit-a retrospective study.

BackgroundAtelectasis after supratentorial craniotomy is common. It can lead to the decrease of arterial partial pressure of oxygen (PaO2) in patients with neurosurgical intensive care units (NICU), and the recovery of neurological function is more and more difficult. However, due to the particularity of maintaining the stability of intracranial pressure (ICP), there are few reports on effective ways to alleviate atelectasis and improve oxygenation in patients with NICU effectively.MethodsA retrospective analysis was conducted to analyze the clinical data of patients with atelectasis who received lung recruitment maneuver in the NICU. This study collected data on 33 patients. Of these, 17 patients had traumatic brain injury and 16 patients had spontaneous intracranial hemorrhage. PaO2, oxygenation index (OI), tidal volume, positive end-expiratory pressure (PEEP), respiratory system compliance, plateau pressure, respiratory rate, minute ventilation and chest computed tomography (CT) or portable chest X-ray images were compared before and after recruitment. As for safety evaluation indicators, we reviewed the invasive arterial blood pressure, heart rate, heart rhythm, and subcutaneous emphysema in all patients. Before and after lung recruitment, the data were compared using the paired t-test and the Wilcoxon test.ResultsCompared with tidal volume 8.1 [6.85–10.05] mL/kg, minute ventilation volume (9.3±1.3 L/min), respiratory system compliance 60 [39–80] mL/cmH2O, respiratory rate 17 [16–21.5] breaths/min, PEEP 4 [4–6] cmH2O, plateau pressure 19 [17–23] cmH2O, PaO2 (104.2±33.17 mmHg) and OI (250.6±87.65 mmHg) before lung recruitment, tidal volume 9 [8.05–10.65] mL/kg, minute ventilation (9.7±1.1 L/min), respiratory system compliance 69 [50–82.5] mL/cmH2O, respiratory rate 17 [14–18.5] breaths/min, PEEP 4 [4–5] cmH2O, plateau pressure 18 [16–19.5] cmH2O, PaO2 (127.3±34.95 mmHg) and OI (306.9±96.52 mmHg) of patients were significantly improved after recruitment after recruitment (all P<0.05). In all patients, chest CT showed a decrease in atelectasis area and bilateral pulmonary exudates in 25 patients after lung recruitment maneuver. X-ray after recruitment in 2 patients showed increased lung tissue transparency and decreased ground-glass shadowing, while improvements were not obvious in 6 patients.ConclusionsFor patients diagnosed with atelectasis in the NICU, lung recruitment maneuver can improve atelectasis, increase PaO2, and improve oxygenation.

Oxygen Therapy: Systems and Indications in the Pediatric and Adult Population

Hypoxemia is defined as the decrease in arterial partial pressure of oxygen (PaO2) below 80 mmHg. One of the ways to alleviate this condition is through oxygen therapy, which consists of administering oxygen at a concentration higher than atmospheric. This therapy is indicated in various pathologies and is aimed to treat hypoxemia and reduce the patient's myocardial demand and respiratory effort. Classically, this treatment has been carried out using low-flow systems, in which the inspiratory fraction of oxygen (FiO2) cannot be regulated. However, an increase in the use of high-flow oxygen therapy (HFO) has been observed in recent years. These systems allow for greater patient comfort as well as more precise regulation of the FiO2. The purpose of this article is to review respiratory physiology to understand respiratory failure from a clinical and pathophysiological point of view. Likewise, the different oxygen therapy systems most widely used are discussed, as well as their indications for acute and chronic pathologies, both in the pediatric and adult populations.

Developing an animal model to detect drug–drug interactions impacting drug-induced respiratory depression

Opioids and benzodiazepines were frequently co-prescribed to patients with pain and psychiatric or neurological disorders; however, co-prescription of these drugs increased the risk for severe respiratory depression and death. Consequently, the U.S. Food and Drug Administration added boxed label warnings describing this risk for all opioids and benzodiazepines. Sedating psychotropic drugs with differing mechanisms of action (e.g., antipsychotics, antidepressants, non-benzodiazepine sedative-hypnotics, etc.) may be increasingly prescribed in place of benzodiazepines. Despite being marketed for years, many sedating psychotropic drugs have neither human nor animal data that quantify or qualify the potential for causing respiratory depression, either alone or in combination with an opioid. In this study, diazepam was selected as the benzodiazepine to detect any additive or synergistic effects on respiratory depression caused by the opioid, oxycodone. Pharmacokinetic studies were conducted at three doses with oxycodone (6.75, 60, 150 mg/kg) and with diazepam (2, 20, 200 mg/kg). Dose dependent decrease in arterial partial pressure of oxygen and increase in arterial partial pressure of carbon dioxide were observed with oxycodone. Diazepam caused similar partial pressure changes only at the highest dose. Further decreases in arterial partial pressure of oxygen and increases in arterial partial pressure of carbon dioxide consistent with exacerbated respiratory depression were observed in rats co-administered oxycodone 150 mg/kg and diazepam 20 mg/kg. These findings confirm previous literature reports of exacerbated opioid-induced respiratory depression with benzodiazepine and opioid co-administration and support the utility of this animal model for assessing opioid-induced respiratory depression and its potential exacerbation by co-administered drugs.

Effects of epidural anesthesia combined with inhalation anesthesia or intravenous anesthesia on intrapulmonary shunt and oxygenation in patients undergoing long term single lung ventilation

Objective:To investigate the effect of epidural anesthesia combined with inhalation or intravenous anesthesia on intrapulmonary shunt and oxygenation in patients undergoing long term single lung ventilation.Methods:Eighty patients, aged 35-75, American Society of Anesthesiology (ASA) classification of I-III, undergoing thoracic surgery with one lung ventilation more than three hour, were randomly divided into propofol group (group Pro), propofol combined with epidural anesthesia group (group Pro+Epi), isoflurane group (group Iso) and isoflurane combined with epidural anesthesia group (group Iso+ Epi), 20 patients in each group. Arterial blood and mixed venous blood were taken for blood gas analysis, and hemodynamic data were recorded at following time points: before induction in supine position (T1), 30min after bilateral lung ventilation (T2), 15min after one lung ventilation (T3), 30min after one lung ventilation (T4), 60min after one lung ventilation (T5), 180min after one lung ventilation (T6), intrapulmonary shunt (Qs/Qt) was calculated according to the correlation formula.Results:Qs/Qt values at T2-6 in four groups were significantly higher than that of T1, and Qs/Qt values at T3-6 was significantly higher than that of T2 (P< 0.05); PaO2 at T2-6 were significantly higher than that of T1, with PaO2 at T3-6 were significantly lower than T2 (P< 0.05). Between groups, Qs/Qt values in group Iso were significantly higher than that of group Pro, Pro+Epi and Iso+Epi at T3-5 (P< 0.05). There was no significant difference in PaO2 between groups (P> 0.05). CI at T3-6 in group Iso and Iso+Epi were significantly higher than that of T1 (P<0.05), and were significantly higher than that of propofol group (P<0.05). MAP at T3-6 in group Pro+Epi and Iso+Epi were significantly lower than that at T1 (P <0.05). Heart rate at T4-6 in group Iso were significantly higher than T1, and higher than group Pro and group Iso+Epi (P <0.05).Conclusion:One lung ventilation may predispose to increase of intrapulmonary shunt and decrease in arterial partial pressure of oxygen; isoflurane inhalation anesthesia is more likely to cause intrapulmonary shunt, but no changes in arterial partial pressure of oxygen.

Exposure of neonatal mice to bromine impairs their alveolar development and lung function.

The halogen bromine (Br2) is used extensively in industry and stored and transported in large quantities. Its accidental or malicious release into the atmosphere has resulted in significant casualties. The pathophysiology of Br2-induced lung injury has been studied in adult animals, but the consequences of Br2 exposure to the developing lung are completely unknown. We exposed neonatal mouse littermates on postnatal day 3 (P3) to either Br2 at 400 ppm for 30 min (400/30), to Br2 at 600 ppm for 30 min (600/30), or to room air, then returned them to their dams and observed until P14. Mice exposed to Br2 had decreased survival (S) and had decreased weight (W) at P14 in the 400/30 group (S = 63.5%, W = 6.67 ± 0.08) and in the 600/30 group (S = 36.1%, W = 5.13 ± 0.67) as compared with air breathing mice (S = 100%, W = 7.96 ± 0.30). Alveolar development was impaired, as evidenced by increased mean linear intercept at P14. At P14, Br2 exposed mice also exhibited a decrease of arterial partial pressure of oxygen, decreased quasi-static lung compliance, as well as increased alpha smooth muscle actin mRNA and protein and increased mRNA for IL-1β, IL-6, CXCL1, and TNFα. Global gene expression, evaluated by RNA sequencing and Ingenuity Pathway Analysis, revealed persistent abnormalities in gene expression profiles at P14 involving pathways of "formation of lung" and "pulmonary development." The data indicate that Br2 inhalation injury early in life results in severe lung developmental consequences, wherein persistent inflammation and global altered developmental gene expression are likely mechanistic contributors.

Effects of doxapram, prethcamide and lobeline on spirometric, blood gas and acid–base variables in healthy new-born calves

A number of drugs have been used to treat asphyxia in new-born calves and the aim of the current study was to investigate the effect of commonly-used stimulant drugs on ventilation, arterial blood gas and acid base variables. A group (n=18) of new-born (3-15 h old) calves were treated in a randomised sequence with doxapram (40 mg, IV), lobeline (5mg, IV) or prethcamide (5 mL, consisting of 375 mg crotethamide and 375 mg cropropamide, buccally). Blood and spirometric measurements, using an ultrasonic spirometer, were collected prior to and 1, 5, 15, 30, 60, 90 min after administration of each drug. Doxapram caused a significant increase in the respiratory rate, peak inspiratory and expiratory flow and minute volume (V(min)) during the 90-min post-treatment study period, although maximum values occurred 1 min after treatment. The V(min) increased from 13.8 ± 5.0 L to 28.5 ± 12.3 L. Prethcamide, but not lobeline, also caused significant increases in inspiratory and expiratory volumes. The effects of doxapram on ventilation were accompanied by an increase in arterial partial pressure of oxygen (P(a)O(2)) (77.7 ± 18.8 mm Hg to 93.2 ± 23.7 mm Hg), a decrease in arterial partial pressure of carbon dioxide (P(a)CO(2)) (42.6 ± 4.9 mm Hg to 33.1 ± 6.6mm Hg), a significant increase in pH and a decrease in bicarbonate concentration and base excess 1 min after treatment. Prethcamide caused a gradual increase in P(a)O(2) and decrease in P(a)CO(2) over 90 min, whereas lobeline had no measurable effect on the investigated variables. Of the three treatments, only doxapram had a distinct stimulatory effect on respiration in healthy neonatal calves and may therefore be useful in the treatment of calf asphyxia.

High intra-abdominal pressure during experimental laparoscopic liver resection reduces bleeding but increases the risk of gas embolism

Various recommendations exist regarding intra-abdominal pressure (IAP) during laparoscopic liver resection. A high IAP may reduce bleeding but at the same time increase the risk of gas embolism. This study investigated the effects of two different IAPs during laparoscopic left liver lobe resection in piglets. Sixteen piglets underwent laparoscopic left liver lobe resection using carbon dioxide pneumoperitoneum of either 8 or 16 mmHg (8 per group). A combination of CUSA System 200™ and LigaSure™ instruments was used for parenchymal division. During resection, a standard injury to the left liver vein was also created to increase the risk of bleeding and/or gas embolism during the operation. Heart rate, cardiac output, and arterial, pulmonary arterial, pulmonary capillary wedge and central venous pressures were measured. Arterial blood gases were monitored continuously. Transoesophageal echocardiography was video recorded to detect and quantify gas embolism within the right cardiac ventricle. The duration of operation and bleeding were noted. High IAP resulted in reduced bleeding (P = 0·016), but gas embolism occurred more frequently (P = 0·001) than with low IAP. Gas embolism disturbed gas exchange, with an increase in arterial pressure of carbon dioxide, and a decrease in arterial partial pressure of oxygen and pH. These effects were sustained for at least 30 min after surgery. High IAP reduces the amount of bleeding but increases the risk of gas embolism. Monitoring for gas embolism is therefore indicated if a high IAP is used during laparoscopic liver resection.

Evaluation of Intramuscular Butorphanol, Azaperone, and Medetomidine and Nasal Oxygen Insufflation for the Chemical Immobilization of White-tailed Deer, Odocoileus virginianus

Chemical immobilization of wildlife often includes opioids or cyclohexamines. These substances are problematic as a result of their required storage, handling, and record-keeping protocols. A potentially useful alternative sedation protocol includes a combination of butorphanol, azaperone, and medetomidine (BAM: 0.43 mg/kg butorphanol, 0.36 mg/kg azaperone, 0.14 mg/kg medetomidine). One risk of wildlife immobilization with any drug combination is hypoxemia. This may be of particular importance when using an alpha 2 agonist such as medetomidine because of its powerful vasoconstrictive effect. In this prospective study, the BAM combination was evaluated for chemical immobilization of white-tailed deer. Additionally, selected physiologic parameters associated with BAM immobilization, including oxygen saturation via pulse oximetry and arterial blood gas measurement, with and without nasal insufflation of oxygen at a relatively low flow of 3 L/min, were evaluated. The BAM combination resulted in a predictable onset of sedation, with a mean induction time to lateral recumbency of 9.8 +/- 3.6 min. All deer recovered smoothly within a range of 5-20 min after reversal with intramuscular administration of naltrexone, atipamazole, and tolazoline (NAT). Clinically relevant decreases in arterial partial pressure of oxygen (PaO2) and oxygen saturation (SpO2) were observed in animals not receiving supplemental oxygen, while both parameters significantly improved for oxygen-supplemented deer. Pulse oximetry with this protocol was an unreliable indicator of oxygen saturation. In this study, altitude, recumbency, hypoventilation, butorphanol- and medetomidine-specific effects, as well as the potential for alpha 2 agonist-induced pulmonary changes all may have contributed to the development of hypoxemia. Overall, capture of white-tailed deer with the BAM/NAT protocol resulted in excellent chemical immobilization and reversal. Because the BAM combination caused significant hypoxemia that is unreliably detected by pulse oximetry but that may be resolved with nasal oxygen insufflation, routine use of oxygen supplementation is recommended.

Orthodromic spike generation from electrical stimuli in the rat carotid body: implications for the afferent spike generation process

Carotid body chemoreceptors respond to a decrease in arterial partial pressure of O(2) with an increase in sinus nerve action potential (AP) activity which initiates a number of protective reflexes. The spike generation process is unresolved but is generally considered to be caused by a synaptic depolarizing potential (SDP) in the nerve endings caused by release of an excitatory transmitter from the glomus cell, which is a secretory cell that is presynaptic to the nerve terminals. To detect the purported SDPs, stimulating electrodes were placed at sites within the carotid body from which orthodromic APs could be evoked at low threshold currents. The probability of AP generation as a function of stimulus current was fitted well to a Boltzmann distribution. Subthreshold electrical stimuli which were expected to summate with subthreshold SDPs, failed, in all instances, to evoke APs at the expected probability. When the stimulus was gated to the occurrence of a spontaneous AP, no change in electrical threshold was observed as the delay between the spontaneous AP and electrical stimulus was increased, despite the presumed disappearance of an SDP in the post-AP period. Decreases in spontaneous AP generation rate, caused by hyperoxia, were associated with only slight changes in the mean orthodromic stimulus threshold, but with a significant increase in slope of the Boltzmann function, suggesting a decrease in the variance of nerve terminal excitability during hyperoxia. These results suggest that AP generation is not due to SDP events; rather, AP generation is likely to be due to a process endogenous to the nerve terminals that modulates the variability of nerve terminal excitability.

Acute Uremia but Not Renal Inflammation Attenuates Aseptic Acute Lung Injury

Acute renal failure (ARF) remains a major clinical challenge, especially in the intensive care setting. Mortality of ARF combined with acute lung injury (ALI) is even higher and may reach 80%. Recent studies have suggested a remote effect of ARF on pulmonary homeostasis. However, it is unknown whether and to what extent ARF clinically affects pulmonary function, in particular oxygenation. For elucidation of the impact of ARF on aseptic ALI, a murine two-hit model that consists of acute uremia (AU) and subsequent ALI was developed. AU was induced by renal ischemia-reperfusion (inflammatory AU) or bilateral nephrectomy (noninflammatory AU). ALI was initiated by intratracheal HCl instillation and characterized by severe, PMN-dependent decrease in arterial partial pressure of O(2) (>70%) in nonuremic mice. Uremic mice, by contrast, showed a significant protection from ALI (decrease in arterial partial pressure of O(2) <40%); this was independent of the type of AU. Reconstitution experiments, in which uremic neutrophils were injected into nonuremic mice and vice versa, identified uremic neutrophils as the primary mediators. Between normal and uremic neutrophils, there were no differences in apoptosis or superoxide production. Pulmonary recruitment of uremic neutrophils, however, was significantly attenuated compared with that of normal neutrophils. This defect was associated with altered surface expression of L-selectin; sialyl Lewis(x), an L-selectin counterreceptor, previously was proved to be critical in aseptic ALI. In conclusion, it is shown that AU but not renal inflammation attenuates aseptic, neutrophil-dependent ALI and exerts an anti-inflammatory effect by attenuating pulmonary neutrophil recruitment.

Orthostatic modification of ventilatory dynamic response to carbon dioxide perturbations

In order to determine whether changes in ventilatory control contribute to the observed decrease in arterial partial pressure of carbon dioxide (PaCO 2) during head up tilt, we assessed ventilatory dynamic sensitivity to changes in PaCO 2 during supine and 70° passive head up tilt. In 24 adult normals, we stimulated the ventilatory control system by switching inspired CO 2 between room air and room air+5% CO 2 in a pseudo random binary sequence. A Box-Jenkins model was used to compute ventilatory response to CO 2. Airflow, CO 2, non-invasive beat by beat blood pressure, ECG and cerebral blood flow velocity (Doppler) were recorded. During tilt, sensitivity of the ventilatory controller to CO 2 disturbance increased (from 0.45 to 0.72 L/min/mm Hg, p<0.005); minute ventilation increased (7.63 to 8.47 L/min, p<0.01), end tidal CO 2 (ETCO 2), cerebral blood flow velocity (CBF) and baroreflex sensitivity decreased (46.9 to 42.9 mm Hg, p<0.001; 84.9 to 72.9 cm/s, p<0.001; and 17.6 to 5.5 ms/mm Hg, p<0.001). The primary observation from our study was that the sensitivity of ventilatory control system to perturbations in ETCO 2 increased during tilt. Taken together with decrease in mean levels of ETCO 2 and an increase in minute ventilation, these results suggest that during tilt, a change in the regulated level or ‘set point’ of PaCO 2 may occur.

Clinical study on patients at early stage of severe acute respiratory symdrome

To elucidate the clinical features of patients at early stage of severe acute respiratory syndrome (SARS). Fifty-three cases of early SARS were studied retrospectively. The data reviewed included those of epidemiology, clinical manifestations, laboratory investigation and roentgenology. The patients consisted of 24 men and 29 women, aged 10.85 years (mean 38+/-16.7 years), including 9 infected health-care professionals (17.0%). The mean incubation period was 7.3+/-7.0 days (3.14 days). The onset symptoms were characterized by fever (100%), cough (49.1%), maylgia (24.5%), shortness of breath (20.8%), malaise (17.0%),and diarrhea (5.7%). Routine blood test during the first to the fifth day of the disease revealed WBCs less than 4.0x10(9) /L in 33 patients (62.3%), 4.0-10.0x10(9)/L in 18 patients (34.0%), lymphopenia in 36 patients (67.9%), and PLT less than 100.0x10(9) in 7 patients (13.2%). The main abnormal X-ray finding was single (75.4%) or bilateral (15.1%) localized patchy clouding opacity. The decrease of arterial partial pressure of oxygen occurred in 26 patients (49.1%). The damage of several organs was common, including the elevated ALT or AST in 20 patients (37.7%), elevated BUN or SCR in 6 patients (11.3%) and elevated LDH or CK or HBDH in 23 patients (43.4%). The clinical manifestations of SARS at the early stage were complex. The close monitoring of the blood cell counts, the blood gas analysis and chest radiography might be crucial to the early diagnosis.

Transoesophageal echocardiography shows high risk of gas embolism during laparoscopic hepatic resection under carbon dioxide pneumoperitoneum.

The ultrasonically activated scalpel (UAS) enables safe and effective laparoscopic tissue dissection, making hepatic resection feasible. This study compared blood loss and risk of gas embolism using the UAS during open hepatic resection and laparoscopic hepatic resection. Female pigs were divided into two groups for laparoscopic (n = 7) and open (n = 5) left hepatic lobectomy. The UAS was used for both tissue cutting and coagulation. Laparoscopic liver resection was performed under carbon dioxide pneumoperitoneum (intraperitoneal pressure 12 mmHg). During surgery animals were monitored haemodynamically by an arterial line and Swan-Ganz catheter. Two-dimensional transoesophageal echocardiography (2D-TEE) was used to detect gas emboli with special attention to the right atrium and ventricle. Gas emboli were graded according to size, and correlated with haemodynamic and blood gas data. During open and laparoscopic hepatic resection the UAS resulted in minimal blood loss and effective tissue dissection. No air embolism was seen during open surgery. With laparoscopic hepatic resection 2D-TEE revealed gas embolism in all animals. Gas embolism was accompanied by cardiac arrhythmia in four of seven animals. No direct correlation was observed between embolism episodes and blood gas variables. There were no deaths after episodes of embolization. A significant decrease in arterial partial pressure of oxygen was seen at the end of the laparoscopic procedure in all animals. The UAS causes minimal blood loss during both open and laparoscopic hepatic resection. Laparoscopic liver dissection under carbon dioxide pneumoperitoneum carries a high risk of gas embolism.

Pulmonary abnormalities after coronary arterial bypass grafting operation: cardiopulmonary bypass versus mechanical stabilization

Background. Cardiopulmonary bypass has been implicated in causing poor pulmonary gas exchange postoperatively in patients undergoing coronary artery bypass grafting procedures. This randomized prospective study was conducted to determine whether patients undergoing coronary artery bypass grafting operations using cardiac stabilization and thereby avoiding cardiopulmonary bypass will have improved pulmonary function postoperatively.Methods. Fifty-eight patients were randomized to one of two groups: coronary artery bypass grafting operation with stabilization or coronary artery bypass grafting operation with cardiopulmonary bypass. Preoperative and postoperative pulmonary gas exchange measurements were performed on intubated patients, including the arterial partial pressure of oxygen on 100% inspired oxygen, the alveolar–arterial oxygen gradient, and pulmonary shunt. Static and dynamic lung compliance measurements were performed postoperatively. Hemodynamic variables (including creatine kinase-MB and troponin levels), intubation time, postoperative bleeding, and blood transfusions were compared.Results. Both study groups had a large decrease in arterial partial pressure of oxygen on 100% inspired oxygen (p < 0.0001) and a significant postoperative increase in the alveolar–arterial oxygen gradient (p < 0.0001). There was no statistical difference in the postoperative gas exchange between the two groups; however, the postoperative pulmonary shunt was significantly better in the stabilization group (24% versus 31%, p = 0.03). The patients were extubated in the intensive care unit earlier in the stabilization group (8.2 hours versus 9.2 hours, not significant). The mean static and dynamic lung compliance postoperatively was lower in the stabilization group, although not statistically significant (p = 0.06).Conclusions. Coronary artery bypass grafting operation using cardiac stabilization technique is safe and avoids the risk of cardiopulmonary bypass. The pulmonary gas exchange postoperatively is comparable to standard cardiopulmonary bypass procedures, but a reduced postoperative pulmonary shunt was seen in the stabilization group.

Improvement in Pulmonary Function and Elastic Recoil after Lung-Reduction Surgery for Diffuse Emphysema

Pulmonary function may improve after surgical resection of the most severely affected lung tissue (lung-reduction surgery) in patients with diffuse emphysema. The basic mechanisms responsible for the improvement, however, are not known. We studied 20 patients with diffuse emphysema before and at least three months after either a unilateral or a bilateral lung-reduction procedure. Clinical benefit was assessed by measurement of the six-minute walking distance and the transitional-dyspnea index, which is a subjective rating of the change from base line in functional impairment and the threshold for effort- and task- dependent dyspnea. Pressure-volume relations in the lungs were measured with static expiratory esophageal-balloon techniques, and right ventricular systolic function was assessed by echocardiography. The patients had significant improvement in the transitional-dyspnea index after surgery (P<0.001). The mean (+/-SD) coefficient of retraction, an indicator of elastic recoil of the lung, improved (from 1.3+/-0.6 cm of water per liter before surgery to 1.8+/-0.8 after, P<0.001). Sixteen patients with increased elastic recoil had a greater increase in the distance walked in six minutes than the other four patients, in whom recoil did not increase (P=0.02). The improved lung recoil led to disproportionate decreases in residual volume as compared with total lung capacity (16 percent vs. 6 percent), but the decreases in both values were significant (P<0.001). Forced expiratory volume in one second increased (from 0.87+/-0.36 to 1.11+/-0.45 liters, P<0.001). End-expiratory esophageal pressure also decreased (P=0.002). These improvements in lung mechanics led to a decrease in arterial partial pressure of carbon dioxide form 42+/-6 to 38+/-5 mm Hg (P=0.006). Furthermore, the fractional change in right ventricular area, an indicator of systolic function, increased from 0.33+/-0.11 to 0.38+/-0.010 (P=0.02). Lung-reduction surgery can produce increases in the elastic recoil of the lung in patients with diffuse emphysema, leading to short-term improvement in dyspnea and exercise tolerance.

Effects of anesthesia induced and maintained by continuous intravenous administration of guaifenesin, ketamine, and xylazine in spontaneously breathing sheep

Summary Anesthesia was induced and maintained in 6 Suffolk wethers by continuous iv infusion of guaifenesin (50 mg/ml), ketamine (1 mg/ml), and xylazine (0.1 mg/ml) in 5% dextrose in water (triple drip) to assess the anesthetic and cardiopulmonary effects. All sheep were positioned in right lateral recumbency. Dosages of triple drip used for induction and maintenance of anesthesia were 1.2 ± 0.02 ml/kg and 2.6 ml/kg/h, respectively. Lack of gross purposeful movement of sheep to electrical stimulation indicated that analgesia and muscular relaxation induced by triple trip were adequate for surgical procedures. Heart rates and arterial blood pressure remained unchanged from baseline values during a 1-hour period of anesthesia. Arterial blood pressures were measured indirectly, using an inflation cuff placed over the metatarsal artery at the heart level. Significant decrease in arterial partial pressure of O2 (Pao2), coupled with an increase in arterial partial pressure of CO2 (Paco2), from baseline values was observed throughout the course of the study. Decrease in Pao2 was observed concomitantly with significant (P &lt; 0.05) increase in respiration rate. Changes in arterial blood gas tensions observed in this study were attributed to respiratory depressant effect induced by anesthetic drugs and right-to-left shunting, perfusion/ventilation mismatch, or both caused by right lateral recumbency. Administration of 100% O2 via the endotracheal tube reduced the magnitude of the decrease in Pao2. All sheep recovered smoothly and stood within 96.3 ± 48.9 minutes after termination of triple drip administration

The effect of gavage feeding on the mechanics of the lung, chest wall, and diaphragm of preterm infants.

Preterm infants when given bolus nasogastric (gavage) feedings have well-characterized decreases in arterial partial pressure of oxygen, increases in arterial partial pressure of carbon dioxide, a tendency to have apnea, and are reported to have no change in the mechanics of breathing. The purpose of this study was to assess the function of the lungs, chest wall, and diaphragm in preterm infants without lung disease before and after gavage feeding. Lung mechanics were measured with a pneumotachograph and esophageal balloon, and the mechanics of the chest wall and diaphragm were assessed by inductance plethysmography and measurement of transdiaphragmatic pressure. After feeding, there was a significant decrease in dynamic lung compliance and increase in the minute ventilation (p less than 0.05). The work performed on the lungs was unchanged. The chest wall became more stable, with a significant decrease in its dynamic compliance (p less than 0.05). The diaphragmatic volume displacement, expressed as a percentage of the minute ventilation, was unchanged. The diaphragmatic work increased significantly (p less than 0.05), and was greater than four times the work performed on the lungs. These results are consistent with previous reports of a decrease in functional residual capacity after feeding. The mechanical stability of the chest wall may have been improved by an increase in the area of apposition of the diaphragm to it, or by an increase in the central drive to breathing after feeding.(ABSTRACT TRUNCATED AT 250 WORDS)