Postoperative Apnea Research Articles

Success rates and complications of awake caudal versus spinal block in preterm infants undergoing inguinal hernia repair: A prospective study.

Background:Inguinal hernia is a common disease in preterm infants necessitating surgical repair. Despite the increased risk of postoperative apnea in preterm infants, the procedure was conventionally performed under general anesthesia. Recently, regional anesthesia approaches, including spinal and caudal blocks have been proposed as safe and efficient alternative anesthesia methods in this group of patients. The current study evaluates awake caudal and spinal blocks in preterm infants undergoing inguinal hernia repair.Materials and Methods:In a randomized clinical trial, 66 neonates and infants (weight <5 kg) undergoing inguinal hernia repair were recruited in Tabriz Teaching Children Hospital during a 12-month period. They were randomly divided into two equal groups; receiving either caudal block by 1 ml/kg of 0.25% bupivacaine plus 20 μg adrenaline (group C) or spinal block by 1 mg/kg of 0.5% bupivacaine plus 20 μg adrenaline (group S). Vital signs and pain scores were documented during operation and thereafter up to 24 h after operation.Results:Decrease in heart rate and systolic blood pressure was significantly higher in group C throughout the study period (P < 0.05). The mean recovery time was significantly higher in group S (27.3 ± 5.5 min vs. 21.8 ± 9.3 min; P = 0.03). Postoperative need for analgesia was significantly more frequent in group S (75.8% vs. 36.4%; P = 0.001). Failure in anesthesia was significantly higher in group S (24.4% vs. 6.1%; P = 0.04).Conclusion:More appropriate success rate, duration of recovery and postoperative need of analgesics could contribute to caudal block being a superior anesthesia technique compared to spinal anesthesia in awaked preterm infants undergoing inguinal hernia repair.

Evaluation of coblation lingual tonsil removal technique for obstructive sleep apnea in Asians: preliminary results of surgical morbidity and prognosticators

Retroglossal obstruction is one of the etiologies causing obstructive sleep apnea (OSA) and can be addressed by removing some tissues of the tongue base. However, because of its deep-seated location, its surgical removal is still challenging. Although coblation technique has been introduced, its efficacy and morbidity need further evaluation, particularly in Asians. This study aimed to assess its safety and effectiveness and to identify outcome prognosticators. Forty-seven OSA patients who underwent coblation lingual tonsil removal were included. Retroglossal obstruction was confirmed by drug-induced sleep videofluoroscopy. Attended full-night polysomnography was performed twice; before and 6 months after surgery in 27 patients. The tongue base was fully exposed with three deep-seated traction sutures, visualized with a 30° or 70° endoscope, and ablated using a coblator. Surgical success was defined with postoperative apnea hypopnea index (AHI) <20 and reduction >50 %. Postoperative morbidities were evaluated. Demographic and polysomnographic parameters between success and failure groups were compared. None of the patients had immediate postoperative hemorrhage. Postoperatively, one patient had delayed hemorrhage and one patient severe respiratory difficulty. Taste loss, tongue dysmotility, dental injury or severe oropharyngeal stricture were absent. A mean AHI decreased from 37.7 ± 18.6 to 18.7 ± 14.8/h (P < 0.001). The success rate was 55.6 %. Their mean minimal oxygen saturation was significantly lower (P = 0.004) in the failure group. Coblation lingual tonsil removal technique showed minimal morbidity and favorable outcome in Koreans. The surgical outcome might be associated with the severity of single respiratory events.

Incidence of Postoperative Respiratory Depression and Postoperative Apnea in the Obese General Surgical Population

Figure 1: A non-invasive Respiratory Volume Monitor (RVM, ExSpiron, Respiratory Motion, Inc.) that provides continuous, real-time, non-invasive measurements of MV, TV and RR. Figure shows standard electrode placement. One electrode is placed at the sternal notch, another is placed on the xiphoid and the third is placed in the right mid-axillary line at the level of the xiphoid. Post-operative respiratory depression (PORD) and sleep disordered breathing, including obstructive sleep apnea (OSA) are well-established risk factors for post-operative respiratory complications, with increased prevalence in the obese population. Current post-operative monitoring does not provide quantitative measurements of ventilation, and the true incidences of PORD and post-operative apnea (POA) remain unknown. Because these incidences often increase with opioid use, accurately determining the risk associated with both PORD and POA is especially important given the prevalent use of opioids and other respiratory depressants in post-operative analgesia.

Morphometric Analysis of Swallowing Mechanics after Surgery for Obstructive Sleep Apnea

Objectives: Apply a new method of analyzing swallowing biomechanics on postoperative obstructive sleep apnea (OSA) patients using parameters of the modified barium swallow (MBS) imaging. Methods: This novel biometric analysis involved two patients following uvulopalatopharyngoplasty, relocation pharyngoplasty, and base of tongue resection for OSA. Postoperative MBS indicated mild swallowing impairment in both patients. Coordinates mapping 10 anatomical landmarks were collected from every frame of the oropharyngeal swallow using ImageJ software. A canonical variate analysis was performed using MorphoJ software with data pooled by subject (S1, S2) and swallowing phase (OP = oral phase, PP = pharyngeal phase). The Mahalobonis distances (D) of the pooled means from each group were defined. Eigenvectors of shape change in these patients were compared to previously published subjects (non-surgical) to document changes in swallowing mechanics. Results: Significant differences in shape change were found for all values: OP versus PP of S1(D = 9.2, P &lt; .0001) and S2 (D = 10.7, P &lt; .0001); OP of S1 versus S2 (D = 45.4, P &lt; .0001); PP of S1 versus S2 (D = 39.2, P &lt; .0001). Eigenvectors indicated reduced pharyngeal shortening and reduced tongue base retraction compared to published data of normal subjects. Conclusions: Tongue base retraction and reduced pharyngeal shortening was noted in this small cohort of patients. These observations are consistent with the postoperative goal of necessary tightening in these areas to avoid collapse. Future controlled studies should be performed to determine whether these changes in swallowing mechanics are specific to surgical interventions or the underlying morphology of OSA patients. This method could potentially be used to quantify the effectiveness of sleep surgical techniques.

Automated analysis of respiratory behavior for the prediction of apnea in infants following general anesthesia.

Infants recovering from general anesthesia are at risk of postoperative apnea (POA), a potentially life threatening event. There is no accurate way to identify which infants will experience POA, and thus all infants with postmenstrual age <; 60 weeks are monitored for apnea in hospital postoperatively. Using a comprehensive, automated analysis of the postoperative breathing patterns, we identified the occurrence of respiratory pauses in 24 infants at age risk for POA. We determined the POA category for each infant by using K-medoids to cluster the duration of the longest respiratory pause. Two clusters were identified, corresponding to APNEA and NO-APNEA, with a threshold of 14.6 s, a value consistent with the clinically accepted threshold of 15 s. K-medoids derived POA labels were used to evaluate the predictive ability of demographic and anesthetic management variables. Weight and the intraoperative doses of atropine, propofol, and opioids discriminated between the APNEA and NO-APNEA groups. A linear Gaussian discriminant analysis classifier provided a very good classification with a probability of detection PD = 0.73 and a probability of false alarm PFA = 0.22. This approach provides a promising tool for the systematic, objective study of infants at risk of POA.

Update on surgery for velopharyngeal dysfunction.

To review journal articles discussing surgery for velopharyngeal dysfunction over the past year. All articles ascertained by a PubMed search relevant to this topic were reviewed. Articles evaluated from the past year discussed the variations, effectiveness, and feasibility of multiple surgical techniques for velopharyngeal dysfunction, including the Furlow palatoplasty, sphincter pharyngoplasty, pharyngeal flap procedure, and other less known novel surgical options. Outcomes, comparisons, and complications were a focus of the majority of the studies. Combinations of the above procedures are also assessed. Nonsurgical options, such as prosthetic devices and pharyngeal augmentation, are mentioned. Multiple surgical options exist to assist patients with velopharyngeal dysfunction. The majority of the surgical options can be highly successful. A multispecialty team is critical in providing patients with the most appropriate treatment for their specific situation. Standardized speech and velopharyngeal dysfunction outcome measures are necessary to allow accurate preoperative and postoperative comparisons, intrasurgeon comparisons, and multi-institutional comparisons. Unfortunately, there is a lack of standardization in speech outcome measures among the studies published over the last year. The risk of postoperative obstructive sleep apnea must be assessed and discussed prior to surgery for any patient scheduled to undergo surgery for velopharyngeal dysfunction. Future studies promise to improve our understanding of velopharyngeal dysfunction and provide further guidance as to the best surgical options to assist these patients.

The metabolic syndrome is a risk factor for postoperative obstructive apnoea and hypoxaemia in morbidly obese patients

The metabolic syndrome is a risk factor for postoperative obstructive apnoea and hypoxaemia in morbidly obese patients

The GAS study: the postoperative apnea outcome in a RCT comparing spinal and general anaesthesia for infant hernia repair

The GAS study: the postoperative apnea outcome in a RCT comparing spinal and general anaesthesia for infant hernia repair

Postoperative apnea and hypercapnia due to intentional breath holding in a freediver

Postoperative apnea and hypercapnia due to intentional breath holding in a freediver

The impact of modified tongue base suspension on CPAP levels in patients with severe OSA.

The aim of this study was to evaluate the effects of modified tongue base suspension (mTBS) procedure on continuous positive airway pressure (CPAP) levels in patients with severe obstructive sleep apnea (OSA). From November 2011 to December 2012, a total of 31 patients with severe OSA who underwent mTBS were included into this prospective case series with planned data collection. Prior to surgery, all the patients were subjected to a polysomnography (PSG) and CPAP titration on two separate nights. Following the surgery, patients were subjected to a control PSG and CPAP titration at the sixth month of follow-up period. The preoperative and postoperative mean apnea hypopnea index (AHI), CPAP titration values, AHI during CPAP use and amount of sleeping time with CPAP were compared. Median age was 48years (range 31-66), and most patients were male (87.0%). Postoperative mean AHI (44.73±17.05 vs. 19.96±19.52), optimal CPAP value (12.64±1.60 vs. 8.00±1.77) and AHI during CPAP use (3.79±1.78 vs. 2.25±1.81) were decreased, and the amount of sleeping time with CPAP (5.29±0.84 vs. 6.52±0.89) was increased significantly (p<0.001 for all parameters). The surgery was considered to be successful when 50% reduction in the mean AHI and/or the decrease of AHI below 20/h were obtained. A total of 24 patients (77.4%) met the surgical success criteria. The mTBS is a safe and feasible procedure with favorable effects on CPAP levels in patients with severe OSA.

Detection of Opioid Induced Respiratory Depression and Postoperative Apnea Using a Noninvasive Respiratory Volume Monitor

Detection of Opioid Induced Respiratory Depression and Postoperative Apnea Using a Noninvasive Respiratory Volume Monitor

Influence of Alprazolam Premedication on the Occurrence of Postoperative Obstructive Apnea

Influence of Alprazolam Premedication on the Occurrence of Postoperative Obstructive Apnea

Factors Associated with Postoperative Exacerbation of Sleep-disordered Breathing

The knowledge on the mechanism of the postoperative exacerbation of sleep-disordered breathing may direct the perioperative management of patients with obstructive sleep apnea. The objective of this study is to investigate the factors associated with postoperative severity of sleep-disordered breathing. After obtaining approvals from Institutional Review Boards, consenting patients underwent portable polysomnography preoperatively, and on postoperative nights 1 and 3 in hospital or at home. The primary outcomes were polysomnography parameters measuring the sleep-disordered breathing. They were treated as repeated measurement variables and analyzed for associated factors by mixed models. Three hundred seventy-six patients, 168 men and 208 women, completed polysomnography on preoperative and postoperative night 1. Age was 59 ± 12 yr (mean ± SD). Preoperative apnea-hypopnea index (AHI) was 12 (4, 26) (median [25th, 75th percentile]) events per hour. Thirty-five patients had minor surgeries, 292 intermediate surgeries, and 49 major surgeries, with 210 general anesthesia and 166 regional anesthesia. The 72-h opioid dose was 55 (14, 85) mg intravenous morphine-equivalent dose. Preoperative AHI, age, and 72-h opioid dose were associated with postoperative AHI. Preoperative central apnea index, male sex, and general anesthesia were associated with postoperative central apnea index. Slow wave sleep percentage was inversely associated with postoperative AHI and central apnea index. Patients with a higher preoperative AHI were predicted to have a higher postoperative AHI. Preoperative AHI, age, and 72-h opioid dose were positively associated with postoperative AHI. Preoperative central apnea, male sex, and general anesthesia were associated with postoperative central apnea index.

Successful use of caudal anesthesia and light sevoflurane mask ventilation for inguinal hernia repair in an infant with multiple large intrapulmonary cysts.

Successful use of caudal anesthesia and light sevoflurane mask ventilation for inguinal hernia repair in an infant with multiple large intrapulmonary cysts.

Postoperative Apnea Induced by Fentanyl and Other Multiple Respiratory-Modulating Factors

Purpose: Opioids are concerned as a major cause of postoperative respiratory depression. In the immediate postoperative period, however, other factors can produce instability of breathing such as pain, agitation, and residual effects of anesthetics. Such factors might be overlooked masked by the fear for opioid-induced respiratory depression. We report a case who presented apnea immediately after emergence from anesthesia that we considered was produced by an interaction among such factors accompanied with fentanyl-induced respiratory depression. Clinical Features: A 31-year-old woman underwent ovarian cystectomy under general anesthesia with continuous infusions of propofol and remifentanil, and bolus doses of fentanyl. Transversus abdominis plane blocks with ropivacaine were given upon completion of surgery. She complained of severe wound pain and was agitated at the emergence from anesthesia. Fentanyl 50 μg was administered intravenously. In several minutes, she developed apnea, unconsciousness, and difficulty of mechanical ventilation via a face mask. The estimated effect site concentration at the onset of the episode (2.9 ng&middotml-1) was approximately the same (3.0 ng&middotml-1) as after 30 min when she regained consciousness and spontaneous breathing. It indicated that not only direct inhibition of the respiratory center by fentanyl but also other stimulatory and inhibitory factors contributed to respiratory arrest. Conclusion: In the immediate postoperative period, transient factors, such as pain, mental instability and anesthetic residues, which are indirectly-related with breathing, can interact each other and with opioids. The interaction would induce apnea through mechanisms combined among direct inhibition of the respiratory center, and modulation of chemical and cortical controls of breathing.

Spinal anesthesia in children: A review.

Even after a vast safety record, the role of spinal anesthesia (SA) as a primary anesthetic technique in children remains contentious and is mainly limited to specialized pediatric centers. It is usually practiced on moribund former preterm infants (<60 weeks post-conception) to reduce the incidence of post-operative apnea when compared to general anesthesia (GA). However, there is ample literature to suggest its safety and efficacy for suitable procedures in older children as well. SA in children has many advantages as in adults with an added advantage of minimal cardio-respiratory disturbance. Recently, several reports from animal studies have raised serious concerns regarding the harmful effects of GA on young developing brain. This may further increase the utility of SA in children as it provides all components of balanced anesthesia technique. Also, SA can be an economical option for countries with finite resources. Limited duration of surgical anesthesia in children is one of the major deterrents for its widespread use in them. To overcome this, several additives like epinephrine, clonidine, fentanyl, morphine, neostigmine etc. have been used and found to be effective even in neonates. But, the developing spinal cord may also be vulnerable to drug-related toxicity, though this has not been systematically evaluated in children. So, adjuvants and drugs with widest therapeutic index should be preferred in children. Despite its widespread use, incidence of side-effects is low and permanent neurological sequalae have not been reported with SA. Literature yields encouraging results regarding its safety and efficacy. Technical skills and constant vigilance of experienced anesthesia providers is indispensable to achieve good results with this technique.

Perioperative management and post-operative course in preterm infants undergoing vitreo-retinal surgery for retinopathy of prematurity: A retrospective study.

Background:Premature infants scheduled for surgery under general anesthesia are more prone to cardio-respiratory complications. Risk factors include post-conception age (PCA), cardiac and respiratory disease, anemia and opioid administration. This retrospective study evaluates the perioperative management and post-operative course (apnea and bradycardia) in premature infants undergoing surgery for retinopathy of prematurity (ROP).Materials and Methods:We analyzed the pre-operative data, anesthesia chart and post-operative course of 52 former premature infants for 56 general anesthesia exposures for ROP surgery.Results:At the time of procedure, median PCA was 51 (36-60) weeks. 71% of the infants were above 46 weeks of PCA. Five infants had cardiac disease and four had a history of convulsion. Four infants had a pre-operative history of apneic spells. The airway was secured with either endotracheal tube (46) or supraglottic device (10). Fentanyl (0.5-1 μg/kg), paracetamol, topical anesthetic drops and/or peribulbar block were administered for analgesia. Extubation was performed in the operating room for 54 cases. Three infants had apnea post-operatively. Seven infants were shifted to neonatal intensive care unit either for observation or due to delayed recovery, persistent apneic spells and pre-existing cardio-respiratory disease.Conclusion:In the present study, intravenous paracetamol and topical anesthetics reduced the total intra-operative opioid requirement, which resulted in low incidence of post-operative apnea. Regional anesthesia may be considered in infants with high risk of post-operative apnea. Infants with PCA > 42 weeks and without any co-morbidity can be managed in post-anesthesia care unit.

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Introduction: Opioid-induced respiratory depression and post-operative apnea (POA) often lead to increased post-operative complications. Inadequate minute ventilation (MV) initiates the spiral of respiratory depression. MV monitoring can provide an early sign of respiratory decompensation. A novel, non-invasive Respiratory Volume Monitor (RVM) provides continuous, real-time respiratory volume traces and reports MV, tidal volume (TV) and respiratory rate (RR) in non-intubated patients. The utility of the RVM derived respiratory depression risk assessment algorithm to direct safe use of opioids, evaluate POA and improve PACU discharge decisions was evaluated. Methods: RVM data were collected from 114 PACU patients following elective orthopedic surgery. 50/114 of the patient’s received opioids. “Predicted” MV (MVPRED) and “Percent Predicted” (MVMEASURED /MVPRED x100%) was calculated for each patient using standard formulas. Prior to opioid administration patients were classified as: “Not-at-Risk”, MV>80% MVPRED and “At-Risk”, MV<80% MVPRED. “Un-Safe” was defined as MV<40% MVPRED. Patients were analyzed post-hoc for POA. Patients were also assessed for “At-Risk” status at PACU 30 minutes prior to discharge. Results: Within 30 minutes of opioid administration, 28% of patients (14 out of 50) became potentially “Un-Safe”. This fraction is higher (43%, 6 out of 14) in the group with POA and lower (22%, 8 out of 36) in the group without POA. 30 minutes prior to discharge, 14% of all patients (16 out of 114) were potentially “Un-Safe”. In the POA group this fraction was marginally increased (19%, 5 out of 26) and in the group without POA was essentially unchanged (13%, 11 out of 88). In the group that received opioids 18% of patients (9 out of 50) were potentially “Un-Safe”, whereas in the group without opioids this fraction was only 11% (7 out of 64). Conclusions: RVM provides real-time MV measurements that can quantify respiratory depression, the effects of opioids and post-operative apnea. RVM may be used to create protocols for opioid administration and discharge criteria. RVM data will allow for better communication of the patients respiratory status and improve patient safety across the continuum of care.

Ultrasonography-guided ilioinguinal-iliohypogastric nerve block for inguinal herniotomies in ex-premature neonates

The ilioinguinal-iliohypogastric (IG-IH) nerve block provides effective opioid-sparing analgesia for inguinal surgeries. The technique is especially useful in apnoea-prone premature neonates with sacral anomalies and coagulopathy. A recent retrospective review of 82 ex-premature neonates who underwent inguinal herniotomy at KK Women's and Children's Hospital, Singapore, reported a success rate of 89% for landmark-guided IG-IH blocks. All blocks in that study were performed by senior paediatric anaesthetists using the landmark-based technique, which relies on fascial clicks. The IG-IH block is expected to be technically more difficult in neonates. There is also a stronger need to ensure success in these patients in order to avoid the use of opioids and reduce the risk of postoperative apnoea. Ultrasonographic guidance has been reported to improve the success of IG-IH blocks in older children to up to 94%. Herein, we report a series of six ex-premature neonates in whom ultrasonography-guided IG-IH blocks were successfully performed using reduced volumes of local anaesthetics (mean volume 0.17 mL/kg) for inguinal herniotomy.

Perioperative Auto-titrated Continuous Positive Airway Pressure Treatment in Surgical Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) may worsen postoperatively. The objective of this randomized open-label trial is to determine whether perioperative auto-titrated continuous positive airway pressure (APAP) treatment decreases postoperative apnea hypopnea index (AHI) and improves oxygenation in patients with moderate and severe OSA. The consented patients with AHI of more than 15 events/h on preoperative polysomnography were randomized into the APAP or control group (receiving routine care). The APAP patients received APAP for 2 or 3 preoperative, and 5 postoperative nights. All patients were monitored with oximetry for 7 to 8 nights (N) and underwent polysomnography on postoperative N3. The primary outcome was AHI on the postoperative N3. One hundred seventy-seven OSA patients undergoing orthopedic and other surgeries were enrolled (APAP: 87 and control: 90). There was no difference between the two groups in baseline data. One hundred six patients (APAP: 40 and control: 66) did polysomnography on postoperative N3, and 100 patients (APAP: 39 and control: 61) completed the study. The compliance rate of APAP was 45%. The APAP usage was 2.4-4.6 h/night. In the APAP group, AHI decreased from preoperative baseline: 30.1 (22.1, 42.5) events/h (median [25th, 75th percentile]) to 3.0 (1.0, 12.5) events/h on postoperative N3 (P < 0.001), whereas, in the control group, AHI increased from 30.4 (23.2, 41.9) events/h to 31.9 (13.5, 50.2) events/h, P = 0.302. No significant change occurred in the central apnea index. The trial showed the feasibility of perioperative APAP for OSA patients. Perioperative APAP treatment significantly reduced postoperative AHI and improved oxygen saturation in the patients with moderate and severe OSA.