Evaluation of nasopharyngeal oxygen, nasal prongs and facemask oxygen therapy devices in adult patients: a randomised crossover trial

Nasopharyngeal oxygen (NPO) therapy may overcome some of the difficulties associated with nasal prongs and facemask oxygen delivery devices. In response to a lack of published studies of NPO therapy in adults, we conducted a prospective randomised crossover trial to compare the effectiveness of NPO, nasal prongs (NP) and facemasks (FM) when used in an adult population (n = 37) from the intensive care unit and general hospital wards. We measured oxygen saturation (SpO2) using pulse oximetry, oxygen flow (litres per minute), respiration rate (per minute) and comfort using a horizontal visual analogue scale. All three devices were effective in maintaining a SpO2 of > or = 95% (NP 97.0 +/- 1.9, NPO 97.7 +/- 1.7, FM 98.8 +/- 1.3%). NPO therapy consumed less oxygen than NP and FM therapy (NP 2.6 +/- 1.0, NPO 2.2 +/- 0.9, FM 6.1 +/- 0.4 l/min, P < 0.001). There was no significant difference in patients' respiratory rates (NP 19.9 +/- 3.2, NPO 19.9 +/- 3.0, FM 19.8 +/- 3.1 per minute, P = 0.491). In terms of comfort, patients rated NP higher than NPO and FM using a horizontal visual analogue scale (100 mm = most comfortable) (NP 65.5 +/- 14.3, NPO 62.8 +/- 19.4, FM 49.4 +/- 21.4 mm, P < 0.001). We conclude that for adult patients, nasal prongs and nasopharyngeal oxygen therapy consume less oxygen and provide greater comfort than facemasks while still maintaining SpO2 > or = 95%.     

Supplementary oxygen administration for elective Caesarean section under spinal anaesthesia

We investigated the necessity for administration of supplementary oxygen to mothers undergoing elective Caesarean section under spinal anaesthesia. Sixty-nine women undergoing elective Caesarean section were randomly allocated to one of three groups to be given either oxygen (40%) by facemask, air by facemask or oxygen at 2 l x min(-1) by nasal cannulae. Umbilical arterial and venous blood samples were taken and analysed immediately after delivery. The results showed that there were no significant differences in the umbilical arterial or venous pH, partial pressure of oxygen and partial pressure of carbon dioxide between any of the three groups. We also assessed the patient acceptability of oxygen administered by facemask vs. nasal cannulae should the need for supplementary oxygen arise. It was found that use of the facemask impeded communication.     

Epidural versus general anaesthesia for elective Caesarean section Effect on Apgar score and acid-base status of the newborn

Elective Caesarean section deliveries over a 5-year period were studied to compare the effect of epidural block with general anaesthesia on the condition of the infant at birth. The Apgar score and umbilical arterial acid-base status were used as determinants of the latter. Epidural block was used in 139 (22.8%) mothers while 471 (77.2%) were performed under general anaesthesia. No babies in the epidural group were severely depressed (Apgar less than 4), compared with 6.2% in the general anaesthesia group. Only 4.3% of the epidural sections were moderately depressed (Apgar 4-6), compared with 15.4% of the others. These differences remained highly significant when infants of less than 2500 g were excluded, and when matched groups were compared. Mean umbilical arterial pH was similar within the two groups (pH 7.28), and was not consistent with asphyxia in almost 90% of the depressed infants. The findings suggest that general anaesthesia, rather than asphyxia or aortocaval compression, is responsible for most of the depressed infants born by elective Caesarean section. This may involve over 20% of babies delivered in this manner, so greater use of epidural block for elective Caesarean section is recommended. Further investigations are required to improve results with general anaesthesia.     

Inspired oxygen concentration during general anaesthesia for caesarean section

The effects on maternal oxygen saturation, foetal wellbeing and umbilical blood gases were compared when parturients received either 30 or 50% oxygen prior to delivery by Caesarean section under general anaesthesia. Maternal arterial oxygen saturation was significantly increased in the group receiving 50% oxygen. There was no difference between the two groups in terms of Apgar score minus colour, time to sustained respiration or umbilical cord blood gas estimations. The use of 30% inspired oxygen during uncomplicated Caesarean section is advocated.     

High-flow nasal oxygen vs. standard flow-rate facemask pre-oxygenation in pregnant patients: a randomised physiological study

High-flow nasal oxygen has been shown to provide effective pre-oxygenation and prolong apnoeic time during intubation attempts in non-pregnant patients. We aimed to compare pre-oxygenation using high-flow nasal oxygen (30–70 l.min⁻¹ oxygen flow) via nasal prongs with standard 15 l.min⁻¹ oxygen breathing via a tight-fitting facemask. Forty healthy parturients were randomly allocated to these two groups, and furthermore each patient underwent the selected pre-oxygenation method with both 3-min tidal volume breathing and 30s tidal breathing followed by eight vital capacity breaths. With 3-min tidal volume breathing, the respective estimated marginal means for high-flow nasal oxygen and standard flow rate facemask pre-oxygenation were 87.4% (95%CI 85.5–89.2%) and 91.0% (95%CI 89.3–92.7%), p = 0.02; with eight vital capacity breaths the estimated marginal means were 85.9% (95%CI 84.1–87.7%) and 91.8% (95%CI 90.1–93.4%, p < 0.0001). Furthermore, high-flow nasal oxygen did not reliably achieve a mean end-tidal oxygen concentration ≥ 90% compared with the standard flow rate facemask. In this physiological study, high-flow nasal oxygen pre-oxygenation performed worse than standard flow rate facemask pre-oxygenation in healthy term parturients.     

General anaesthesia versus epidural anaesthesia for primary caesarean section--a comparative study.

Forty-seven healthy parturients undergoing elective Caesarean section were randomly allocated to either general anaesthesia (n = 24) or epidural anaesthesia (n = 23) under standardized anaesthetic and surgical conditions. Seven women of the epidural group required additional systemic analgesia or sedation following delivery of the neonate. Nine of 24 newborns obtained 1-min Apgar scores below 7 after general anaesthesia compared to only 3/23 after epidural anaesthesia. The time period to establish normal colour in the babies was 2.2 min after epidural and 4.9 min after general anaesthesia. Three of the 24 general-anaesthesia newborns demonstrated a tendency to hypotonia compared to only one in the epidural group. Twenty-four hours and 7 days after delivery all infants of both groups were completely normal. At the time of delivery maternal PO2 was higher in the general anaesthesia compared to the epidural group, due to higher inspired oxygen concentrations. Comparable results were obtained in umbilical PO2 venous values; lower pH values, however, were observed in the umbilical artery after general anaesthesia. There were no significant differences in the glucose levels between the groups. A significant correlation was established between uterine incision-delivery interval and 1-min neonatal Apgar scores in the general-anaesthesia group, but not in the epidural group. Our investigation did not show either the incision-delivery interval or the start of operation-delivery interval to play a role in neonatal outcome. Epidural anaesthesia is superior to general anaesthesia in Caesarean section under normal conditions with regard to neonatal outcome. Whether this is also true for critical conditions cannot be concluded from this study.     

A comparison of spinal and general anaesthesia for elective caesarean section: effect on neonatal condition at birth

The condition of 74 neonates delivered by elective caesarean section under general anaesthesia was compared with that of 63 neonates delivered under spinal anaesthesia. When the uterine incision - delivery interval was less than 3 min, neonates in the spinal group exhibited a higher Apgar score at 1 min (P < 0.002) and a higher mean umbilical venous pH (P < 0.05) than the equivalent general anaesthesia group; a significantly greater proportion of the neonates delivered under general anaesthesia had an umbilical venous pH<7.28 at delivery (P < 0.05), a fact which previous work suggests is important. Among anaesthetized mothers inspired oxygen concentration (33% or 50%) before delivery had no significant effect upon neonatal outcome. It is concluded that neonates delivered at elective Caesarean section under spinal anaesthesia are in better condition than those delivered under general anaesthesia.     

Determining the effective pre-oxygenation interval in obstetric patients using high-flow nasal oxygen and standard flow rate facemask: a biased-coin up–down sequential allocation trial

Using biased-coin sequential allocation, we sought to determine the effective time interval in 90% of healthy parturients to achieve a target endpoint end-tidal oxygen of ≥ 90% using standard flow rate facemask and high-flow nasal oxygen. Eighty healthy parturients were randomly assigned to standard facemask (n = 40) or high-flow nasal oxygen (n = 40) groups; half of the parturients in the high-flow nasal oxygen group also used a simple no-flow facemask to minimise air entrainment. The effective time interval for 90% of parturients to achieve the target endpoint for standard facemask was 3.6 min (95%CI 3.3–6.7 min), but could not be estimated for the high-flow nasal oxygen groups with or without an additional simple facemask, as eight minutes was insufficient to achieve the target endpoint for 55% and 92% of parturients, respectively. Furthermore, after three minutes, the target endpoint was reached by 71% in the standard facemask group vs. 0% in the high-flow nasal oxygen groups. After four minutes, the target endpoint was reached by 100% in the standard facemask, 80% in the high-flow nasal oxygen with simple facemask and 67% in the high-flow nasal oxygen groups. Beyond four minutes, there was no improvement in pre-oxygenation success using high-flow nasal oxygen. In conclusion, under the conditions of our study, the effective time interval for 90% of parturients to achieve an end-tidal oxygen ≥ 90% for standard flow rate facemask was estimated to be 3.6 min, but could not be estimated for high-flow nasal oxygen groups even after eight minutes.     

Fluid preload before spinal anaesthesia in Caesarean section: the effect on neonatal acid-base status

BACKGROUND AND OBJECTIVE: We evaluated the effect of two different preload solutions: (i) Ringer's lactate (compound sodium lactate intravenous infusion BP) and (ii) 0.9% sodium chloride solution on the neonatal acid-base status of the newborn infants. The two standard regimens were compared to detect a possible difference. METHODS: A 2 L crystalloid fluid bolus was administered immediately before spinal anaesthesia for elective Caesarean section in two groups of 20 healthy parturients, while rigorously maintaining maternal normotension. RESULTS: No significant differences in the Apgar scores at 1 and 5 min, or infant well-being were demonstrated in either of the two groups. The data show that umbilical artery PCO2 is lower in the Ringer's lactate group and that pH is insignificantly higher by 0.03. CONCLUSIONS: The choice of Ringer's lactate or saline for fluid preload does not have any effect on neonatal well-being.     

Is massive fluid load indispensable for the parturient immediately before regional anesthesia?

One hundred healthy parturients scheduled for elective cesarean section were studied prospectively. Fifty patients received spinal anesthesia with 12mg of hyperbaric tetracaine and were defined as the spinal group. Other fifty patients received epidural anesthesia with 300mg of lidocaine and were defined as the epidural group. A half of patients in each group were given 1,000ml of Ringer's lactate immediately before the regional anesthesia (prehydrated). Rapid hydration was not given to another half of them (non-prehydrated). In the spinal group, ephedrine administration was needed significantly less frequently for prehydrated patients than for non-prehydrated ones. And the mean dose of this drug for prehydrated patients was significantly less than that for non-prehydrated ones. In the epidural group, though prehydration tended to prevent maternal hypotension, neither rate of ephedrine administration nor mean doses of this drug showed any significant difference between prehydrated and non-prehydrated patients. Prehydration did not improve significantly neither acid-base balances of umbilical arterial and venous blood nor Apgar scores of the neonates in either group. We conclude that massive fluid load is not indispensable immediately before the regional anesthesia for the parturient. Furthermore, because this method is not reliable, its advantages and disadvantages including the possibility of enhancing pulmonary edema should be evaluated.     

Epidural lidocaine for cesarean delivery of the distressed fetus

Lidocaine with epinephrine and sodium bicarbonate has a rapid onset of action. We therefore wished to compare its use with that of chloroprocaine for urgent cesarean delivery. Thirty parturients for cesarean section under epidural anesthesia were divided into three groups. Group 1 required elective cesarean section and served as the control group for neonatal lidocaine levels. Groups 2 and 3 had been receiving epidural infusions of 0.125% bupivacaine with epinephrine 1:400,000 and required urgent cesarean section. They were randomized to receive either 1.5% lidocaine with epinephrine or 3% chloroprocaine, both with sodium bicarbonate 2 ml in a total volume of 25 ml. All patients had adequate anesthesia and none required supplementation. The time from completion of injection to the achievement of a T4 sensory level was significantly shorter in the chloroprocaine group (3.1 vs. 4.4 min). There were no differences in Apgar scores or Neurologic and Adaptive Capacity Scores between the lidocaine and chloroprocaine groups. Lidocaine was detectable in maternal serum from four of the urgent cases and all of the elective cases. It was detectable in five neonates from the elective group but none from the emergency group. In parturients with preexisting epidural catheters and a baseline epidural infusion to maintain a T10 sensory level, chloroprocaine is faster in onset than lidocaine, but the difference in this study was only 1.3 min, and both agents provided excellent anesthesia.     

Lignocaine 2% with adrenaline for epidural Caesarean section

A randomised double blind controlled trial of freshly prepared 2% lignocaine with 1/200,000 adrenaline and 0.5% plain bupivacaine was conducted on 60 women undergoing elective Caesarean section. The use of the former enabled epidural blockade to above the T6 dermatome to be established in a significantly shorter time than with bupivacaine (p less than 0.005). The quality of sensory blockade and incidence of complications was similar in the two groups. The solutions were of similar potency as measured by the volume required per segment blocked. Motor blockade was more intense with 2% lignocaine with adrenaline (p less than 0.03). More neonates had moderately depressed Apgar scores (5-7) at one minute in the lignocaine group but this difference was not statistically significant, and there was no difference in the distribution of Apgar scores at 3 minutes. Lignocaine with 1/200,000 adrenaline is a useful alternative to 0.5% plain bupivacaine when it is desired to establish rapidly epidural blockade for Caesarean section.     

Continuous infusion epidural analgesia in parturients receiving bupivacaine, chloroprocaine, or lidocaine--maternal, fetal, and neonatal effects

The effects of epidural analgesia for labor and delivery using a continuous infusion technique on fetal heart rate, uterine activity, maternal blood pressure, Apgar scores, neonatal acid-base status, and the Neurologic and Adaptive Capacity Scoring System were studied in 61 parturients. Group I (n = 23) received initial test and therapeutic doses of 2 and 6 ml of 0.5% bupivacaine followed by an infusion of 0.125% at a rate of 14 ml/hr. Group II (n = 19) received 2 and 6 ml of 2% chloroprocaine followed by an infusion of 0.75% at a rate of 27 ml/hr. Group III (n = 19) received 2 and 6 ml of 1.5% lidocaine followed by an infusion of 0.75% at a rate of 14 ml/hr. None of the three local anesthetics used had any significant effect on baseline fetal heart rate or uterine activity. In cases in which monitoring of fetal heart rate was both technically satisfactory and continuous, late and variable decelerations in fetal heart rate were seen in 10 of 17, 3 of 18, and 2 of 19 of the fetuses in groups I, II, and III, respectively. The incidence was significantly higher in group I than in groups II or III (P less than 0.05). Apgar scores and neonatal acid-base status were equally good in all three groups. Neurologic and adaptive capacity scores did not differ among the three groups of neonates, nor did any of the neonates in the three groups score lower than a control group of 19 neonates whose mothers did not receive any analgesia or medications for labor and delivery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Supplementation of general anaesthesia with tramadol or fentanyl in parturients undergoing elective Caesarean section

Purpose

Tramadol has been recommended for analgesia in parturients undergoing vaginal delivery. The present report investigated the effect of tramadol versus fentanyl on umbilical vein (UV) blood gases and Apgar scores of neonates delivered via elective Caesarean section under general anaesthesia.

Methods

Forty ASA I or II parturients undergoing elective Caesarean section were included in a randomized double-blinded study. The patients were divided into a tramadol (n = 20) and fentanyl groups (n =.20). During preoxygenation, one group received 100 mg tramadoliv, while the second received 100 μg fentanyl. Anaesthesia was induced in both groups by 3 mg·kg^?1 thiopentone and 1.5 mg·kg^?1 succinylcholine was given to facilitate tracheal intubation. Anaesthesia was maintained during the induction-delivery period with nitrous oxide 50% in oxygen.

Results

The umbilical vein PO₂ was higher in the fentanyl (34 ± 5 mmHg) than in the tramadol group (24 ± 6 mmHg) (P < 0.01), while the UV PCO₂ was higher in the tramadol group (50 ± 5vs 45 ± 4 mmHg) (P 0.01). The Apgar scores at one and five minutes were not different between the two groups. Post operatively, two patients in the tramadol group recalled the crying of their newborn at delivery.

Conclusion

Tramadol is associated with a high incidence of intraoperative maternal recall and can result in lower umbilical vein PO₂ and higher PCO₂ than in the fentanyl group.     

Vasopressor therapy for hypotension due to epidural anesthesia for cesarean section

Maternal hemodynamic changes and neonatal acid-base status were assessed in 127 healthy patients undergoing elective cesarean section under epidural anesthesia. An impedance cardiograph was used to measure stroke volume (SV), ejection fraction (EF) and end-diastolic volume (EDV). In addition, neonatal umbilical venous and arterial PO2, PCO2, pH, base excess, lactate, pyruvate, excess lactate, and L/P ratio were measured at birth. Patients were divided into three groups. Group 1 (n = 53) required no vasopressor (normotensive controls). In Group 2 (n = 37), mean blood pressure (BP) decreased from 90 mmHg (13.3 kPa). In Group 3 (n = 37), BP decreased from 83 mmHg to 62 mmHg (11.1 to 8.2 kPa), and phenylephrine was administered in 100 micrograms increments to maintain systolic BP greater than 100 mmHg (13.3 kPa). In Groups 2 and 3 the SV and EDV decreased 43% and 33% respectively when hypotension developed. Both vasopressors restored BP, SV and EDV to near baseline values. Neonatal Apgar scores and acid-base profiles were not significantly different among the three groups of neonates, nor were they different between the two hypotensive groups. It is concluded that: 1) transient maternal hypotension does not affect neonatal acid-base status; 2) both ephedrine and phenylephrine increase cardiac preload; and 3) an alpha agent like phenylephrine does not cause fetal acidosis when used for treating maternal hypotension.     

The effects of regional anaesthesia for caesarean section on maternal and fetal blood flow velocities measured by doppler ultrasound

We studied the effects of spinal anaesthesia (Group S), epidural anaesthesia (Group E), and combined spinal and epidural anaesthesia (Group SE), on maternal and fetal blood flow in 24 healthy parturients (n = 8/group) with uncomplicated singleton pregnancies using Doppler technique. Prior to the induction of anaesthesia, the patients were prehydrated with balanced electrolyte solution 15 ml kg^-1 over a period of 15 min. After the induction of regional anaesthesia, the systolic blood pressure was maintained within 15% limits of the preoperative values using prophylactic etilefrine infusion in Groups S and SE. The flow velocity waveforms of the maternal femoral artery, the main branch of the uterine artery (placental side), the foetal umbilical and middle cerebral arteries were recorded by Doppler technique before and after prehydration as well as after onset of T7 analgesia and the pulsatility indices (PI) were derived. Rapid intravenous prehydration had no effects on uteroplacental or fetal circulation as indicated by unaltered uterine, umbilical, and fetal middle cerebral artery Pis. After the onset of T7 analgesia, the uterine artery PI was increased in Group S indicating increased uterine vascular resistance while no changes occurred in Groups E and SE. No adverse effects were observed on the neonates as indicated by the Apgar score and the umbilical artery and vein acid–base status in any of the groups.     

Perioperative maternal and neonatal acid-base status and glucose metabolism in patients with insulin-dependent diabetes mellitus.

Maternal and neonatal acid-base status and glucose metabolism were studied in 20 patients with insulin-dependent diabetes mellitus (group 1) undergoing elective cesarean section under lumbar epidural anesthesia. All patients were given glucose/insulin infusion before delivery. Fifteen healthy patients with iatrogenic hyperglycemia (group 2) and 15 healthy euglycemic patients (group 3) served as controls. Results were expressed as mean +/- 1 SE and were analyzed using analysis of variance and chi 2 analysis at P less than 0.05. No significant differences were seen at delivery either in maternal arterial and neonatal umbilical venous and arterial blood acid-base status or in neonatal Apgar scores among the three groups. Patients in groups 1 and 2 had larger blood glucose concentrations than those in group 3 (P = 0.01). Diabetic mothers and their neonates had a 25%-50% reduction in pyruvate concentration in maternal venous, and neonatal umbilical venous and arterial blood compared with that in the other two groups (P = 0.001). Postpartum neonatal hypoglycemia (less than 30 mg/dL) developed in seven of the group 1 neonates (P = 0.05). Thus, epidural anesthesia in diabetic women is associated with normal acid-base status in the mother and in the neonate. The data also show an increased incidence of neonatal hypoglycemia and altered maternal and neonatal glycolysis in patients with diabetes mellitus.     

Neonatal effects of adding epidural fentanyl to 0.5% bupivacaine for caesarean section

Epidural injection of opioids has been introduced to improve analgesia during labour and caesarean section. This study was designed to quantify placental transfer of fentanyl and to evaluate neonatal effects of adding fentanyl to 0.5% bupivacaine for epidural anaesthesia in women undergoing elective caesarean section at term. The parturients were randomly allocated to one of four groups of 20, who received either saline (control) or 50, 75 or 100 microg of fentanyl added to 20 ml of 0.5% bupivacaine. Apgar scores, time to sustained respiration and umbilical acid-base values did not differ among the groups. The median (interquartile range) umbilical artery to maternal vein fentanyl concentration ratio was 0.34 (0.26-0.48) when the fentanyl groups were taken together. Neurologic and adaptive capacity scores were evaluated at 2 and 24 h. Neonates whose mothers received fentanyl had lower scores with regard to supporting reaction at 2 h and active tone at 24 h, when compared to controls (P<0.05), but there were no differences among the groups with regard to the other test criteria in the neurobehavioural test. In conclusion, epidural injection of fentanyl 50-100 microg did not produce depression of the term neonate.     

Effect of maternal facial oxygen on neonatal behavioural scores during elective Caesarean section with spinal anaesthesia

BACKGROUND AND OBJECTIVE: For many, the administration of additional oxygen to the women receiving regional anaesthesia for Caesarean section is traditional, but for others it is controversial because of doubts about its efficacy. The aim of our study was to determine if beneficial effects of maternal oxygen therapy on the fetus could be revealed using a neonatal behavioural scoring system. METHODS: Sixty women with a normal singleton pregnancy beyond 36 weeks gestation, undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups: Group 1 received air and oxygen mixture through a Hudson style face mask (FiO2 of 0.21-0.25). Group 2 received FiO2 of 0.40-0.60 through an identical Hudson style face mask. Neurologic Adaptive Capacity Score on all the infants within 5 min of birth and between 10 and 24 h after the Caesarean delivery was performed. Apgar score, umbilical venous blood oxygen tension and umbilical artery standardized base excess were recorded. RESULTS: Initial Neurologic Adaptive Capacity Scores at birth in Groups 1 and 2 were 32.6 (SD 4.6) and 31.3 (SD 4.3), respectively. Latter scores were 36.0 (SD 3.0) and 36.5 (SD 1.9), respectively. Neither were statistically significant. There were no significant differences between the groups for any of the recorded variables. CONCLUSIONS: Administering maternal oxygen using a standard commercial Hudson style face mask does not appear to significantly improve oxygen delivery to, nor does it influence acidosis or behavioural effects in, the normal neonate at elective Caesarean delivery with spinal anaesthesia.     

剖宫产术病人硬膜外左旋布比卡因的胎盘转移

目的 评价剖宫产术病人硬膜外左旋布比卡因的胎盘转移情况.方法 择期硬膜外麻醉下剖宫产术病人60例.于L1,2或L2,3间隙进行硬膜外穿刺,穿刺成功后注射0.5%左旋布比卡因5ml(含1:20万肾上腺素)试验剂量,5 min后无脊麻征象后,追加9～12 ml,5 min后再追加1次.娩出时抽取脐动脉血样,进行血气分析;于娩出后l、5min行Apgar评分.选择30例病人,娩出时抽取母体静脉血样和脐静脉血样,采用高效液相色谱法测定血浆左旋布比卡因浓度.结果 在硬膜外注药结束后10～22 min60例胎儿娩出,新生儿Apgar评分均≥7分,脐动脉血Ph值均≥7.25.娩出时母体静脉血与脐静脉血血浆左旋布比卡因浓度分别为0.35 ±0.24、(0.24±0.21)μg/ml,脐静脉血与母体静脉血血浆左旋布比卡因浓度的比值为0.7 ±0.3.结论 宫产术病人硬膜外左旋布比卡因可通过胎盘,脐静脉血与母体静脉血左旋布比卡因浓度的比值为0.7.