Retrospective Study of Postoperative Pulmonary Complications in Patients with Cervical Spine Pathology

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1 98 Pulmonry Originl Article Compliction fter Cervicl Spine Surgery THIEME Retrospective Study of Postopertive Pulmonry Complictions in Ptients with Cervicl Spine Pthology Sury Kumr Dube 1 Mihir Prksh Pndi 1 Arvind Chturvedi 1 Shilender Kumr 2 1 Deprtment of Neuronesthesiology nd Criticl Cre, All Indi Institute of Medicl Sciences, New Delhi, Indi 2 Deprtment of Anesthesiology, Pin Medicine nd Criticl Cre, All Indi Institute of Medicl Sciences, New Delhi, Indi Address for correspondence Mihir Prksh Pndi, MD, Deprtment of Neuronesthesiology nd Criticl Cre, 7th Floor, Neurosciences Center, All Indi Institute of Medicl Sciences, New Delhi , Indi (e-mil: pndimihir@gmil.com). J Neuronesthesiol Crit Cre 2018;5: Abstrct Keywords cervicl spine complictions pulmonry risk fctors Bckground Postopertive pulmonry compliction (PPC) fter cervicl spine surgery is known to increse ptient morbidity nd mortlity s well s the hospitl nd intensive cre unit (ICU) sty. However, studies ddressing this issue re scrce in the current literture. The im of this study ws to find out the incidence nd vrious fctors ssocited with PPC in ptients undergoing cervicl spine surgeries. Mterils nd Methods It is retrospective study in tertiry cre hospitl. Two hundred nd seven ptients who underwent different cervicl spinl surgeries were included in this study. Vrious periopertive dt including demogrphy, history of smoking, ssocited systemic illness, type nd site of lesion, preopertive respirtory sttus, nd signs of involvement of lower crnil nerves were collected. The incidence nd the risk fctors for PPC were found out. Sttisticl nlysis ws done using chi-squre/fisher s exct test/student s t-test, followed by univrite nd multiple logistic regression nlysis. Results The incidence of PPC in our study ws 39.6%. Vrious pulmonry complictions observed were difficulty in brething requiring some intervention (19.3%), pneumoni (5.3%), trcheobronchitis (3.9%), rteril desturtion (3.4%), reintubtion (3.4%), telectsis (1.3%), pleurl effusion (0.97%), pneumothorx (0.97%), nd cute respirtory distress syndrome (ARDS) (0.97%). Preopertive respirtory bnormlity, cervicl lminectomy nd instrumenttion surgery nd postopertive mechnicl ventiltion of > 24 hours durtion were found to be independent risk fctors for occurrence of PPC. Conclusions The ptients with cervicl spinl cord pthology re t incresed risk for PPC. Preopertive respirtory bnormlity, postopertive mechnicl ventiltion of > 24-hour durtion, nd cervicl lminectomy nd instrumenttion surgery re independent risk fctors for PPC. Introduction Ptients with cervicl spine pthology cn hve respirtory system dysfunction due to wekness of respirtory muscles/ diphrgm or involvement of the respirtory center nd lower crnil nerves secondry to medullry compression. 1,2 Pulmonry spirtion, telectsis, poor respirtory function, nd indequte cough mechnism secondry to diphrgm or respirtory muscle involvement cn led to preopertive respirtory bnormlities in ptients with cervicl spine pthology tht might get exggerted in the postopertive period becuse of vrious nesthetic nd surgicl cuses. 3 5 Prolonged trchel intubtion/trcheostomy in the postopertive period further cn increse the incidence of pulmonry received My 14, 2018 ccepted My 14, 2018 published online June 10, 2018 DOI /s ISSN Copyright 2018 Indin Society of Neuronesthesiology nd Criticl Cre

2 99 complictions. 6,7 However, studies ddressing pulmonry complictions in ptients specificlly with cervicl spine pthology re scrce. Therefore, the objective of the study ws to find out the incidence of postopertive pulmonry compliction (PPC) in ptient undergoing cervicl spine surgeries nd to identify the fctors ssocited with PPC in these ptients. Mterils nd Methods After pprovl of institute ethics committee, records of the ptients who underwent surgery for different cervicl spinl cord/vertebrl pthology within stipulted 2-yer-durtion were reviewed. Ptients who underwent surgery for crniovertebrl junction (CVJ) nomly were excluded from the study. Demogrphic dt nd dt regrding ssocited systemic illness, type nd site of pthology, preopertive respirtory sttus, nd signs of involvement of lower crnil nerves were collected. If there were documented positive signs or symptoms of respirtory bnormlity, need for irwy or respirtory support, bnorml sounds on chest usculttion, or presence of bnorml chest X-ry, the ptient ws considered to hve preopertive respirtory system bnormlity. Dt bout nesthetic technique, intubtion techniques, surgicl procedure, levels of the cervicl vertebr operted, durtion of surgery nd nesthesi, mount of blood loss, mount of intrvenous fluid used, mount of blood, nd blood component trnsfused were noted. Postopertive dt were reviewed for the presence of PPC, need for reintubtion/other irwy intervention, need nd durtion of postopertive mechnicl ventiltion, blood nd blood component trnsfusion, other complictions, need for reexplortion, postopertive use of methyl prednisolone, nsogstric tube (NGT) insertion, nd durtion of intensive cre unit (ICU) nd hospitl sty. Presence of ny one or more of the following ws considered s PPC: hypoventiltion, hyperventiltion, presence of bnorml signs or symptoms of pulmonry system, difficulty in brething requiring intervention (i.e., intubtion, irwy insertion, nebuliztion, mneuvers to keep irwy ptent, etc.) rteril oxygen sturtion < 90% needing oxygen supplementtion, telectsis, pneumothorx, pleurl effusion, hemothorx, bnorml chest usculttory findings, pneumoni, trcheobronchitis, or cute respirtory distress syndrome (ARDS). The sttisticl nlysis ws performed using Stt 11.0 (College Sttions, Texs, United Sttes). Dt were presented s number (%)/men ± stndrd devition (SD)/medin (rnge). Demogrphic nd clinicl chrcteristics of the ptients were compred using chi-squre/fisher s exct test (for ctegoricl vribles) nd Student s t-test (for continuous vribles). The risk fctors for PPC were found out using univrite nlysis followed by multiple logistic regression nlysis. The results were shown s odds rtio (OR) (95% confidence intervl [CI]). p-vlue < 0.05 ws considered s significnt. Results Dt of 207 ptients (160 [80.7%] mles) were nlyzed in this study. Different demogrphic chrcteristics of the ptients re shown in Tble 1. The medin ge of the ptients ws 49 yers (3 months 86 yers), nd most of the ptients were of ASA (Americn Society of Anesthesiologists) clss I (54.1%) nd II (44.9%). Periopertive chrcteristics of the ptients re shown in Tble 2. Forty-four (21.3%) ptients were smokers nd 34 (16.4%) hd preopertive respirtory bnormlity. Mjority of the ptients hd prolpsed intervertebrl disc (39.7%), nd 28.5% of ptients hd involvement of multiple cervicl levels. Mjority of our ptients underwent nterior cervicl discectomy nd fusion (ACDF) (39.7%) nd cervicl lminoplsty (39.1%) surgery. The surgicl pproch ws nterior in 50.7% ptients nd posterior in 48.3% ptients. The men durtions of surgery nd nesthesi were ± 91 minutes nd ± 98.1 minutes, respectively. Forty-five (27.8%) ptients required mechnicl ventiltion in the postopertive period, nd the men durtion of mechnicl ventiltion ws 13.1 ± 60.7 hours. Five (2.4%) ptients required trcheostomy. Methyl prednisolone ws Tble 1 Demogrphic chrcteristics of the ptients (n = 207) Prmeter Frequency Age (y) b 49 (3 mo 86 y) Weight (kg) b 60 (5 105) ASA sttus Sex I 112 (54.1) II 93 (44.9) III 2 (1.0) IV 0 Mle 160 (80.7) Femle 47 (19.3) Abbrevition: ASA, Americn Society of Anesthesiologists. Dt shown s number (%) of ptients unless specified. b Dt shown s medin (rnge). Journl of Neuronesthesiology nd Criticl Cre Vol. 5 No. 2/2018

3 100 Tble 2 Periopertive chrcteristics of the ptients (n = 207) Prmeter Frequency Smokers 44 (21.3) Preopertive respirtory system bnormlity 34 (16.4) Dignosis PIVD 82 (39.7) SOL 31 (14.8) Myelopthy 37 (17.9) others 57 (27.6) Level of injury Upper 13 (6.3) Middle 46 (22.2) Lower 89 (43) Multiple 59 (28.5) Surgery performed ACDF 82 (39.7) Lminoplsty 81 (39.1) Lminectomy nd instrumenttion 44 (21.2) Approch Anterior 105 (50.7) Posterior 100 (48.3) Combined 2 (1) Durtion of surgery (minutes) b ± 91 Durtion of nesthesi (minutes) b ± 98.1 Blood loss (ml) b ± Fluid (ml) b 2473 ± Mechnicl ventiltion 45 (27.8) Durtion of mechnicl ventiltion (h) b 13.1 ± 60.7 Need for trcheostomy 5 (2.4) Methyl prednisolone dministrtion 24 (11.6) ICU sty (h) b 36.6 ± 52.3 Hospitl sty (d) b 5.5 ± 5.1 Abbrevitions: ACDF: nterior cervicl discectomy nd fusion; ASA: Americn Society of Anesthesiologists; ICU, intensive cre unit; PIVD: prolpsed intervertebrl disc; SOL, spce-occupying lesion. Dt shown s number (%) of ptients unless specified. b Dt shown s men (±SD). dministered in 24 (11.6%) ptients. The men ICU sty (ICS) ws 36.6 ± 52.3 hours, wheres the men hospitl sty (HOS) ws 5.5 ± 5.1 dys. In the postopertive period, 82 (39.6%) ptients developed vrious pulmonry complictions ( Tble 3). The most common pulmonry compliction ws difficulty in brething requiring some intervention (19.3%). Bsed on the presence or bsence of PPC, ptients were divided into two groups: group P (presence of PPC) nd group A (bsence of PPC). Comprison of different demogrphic nd periopertive vribles is shown in Tble 4. Ptients of both the groups were comprble in terms of ge, sex distribution, weight, ASA sttus, nd level of pthology. Group P hd significntly more number of smokers, more ptients with preopertive respirtory bnormlity, longer durtion of surgery nd nesthesi, mount of blood loss intrvenous fluid dministrtion, nd durtion of postopertive mechnicl ventiltion thn group A. Incidence of trcheostomy nd methyl prednisolone dministrtion ws more in group P thn group A. The ICU sty nd hospitl sty were longer in group P thn group A. The results of univrite nlysis re shown in Tble 5. In univrite nlysis, ge > 60 yers, smoking, preopertive respirtory bnormlity, posterior pproch surgery, cervicl lminoplsty nd cervicl lminectomy nd instrumenttion surgery, durtion of nesthesi > 300 minutes, intropertive blood loss > 500 ml, intrvenous fluid dministrtion of > 2,000 ml, dministrtion of methyl prednisolone, postopertive mechnicl ventiltion > 24 hours, nd neoplstic spce-occupying lesions were sttisticlly significnt risk fctors for PPC. Journl of Neuronesthesiology nd Criticl Cre Vol. 5 No. 2/2018

4 101 Tble 3 Incidence of different postopertive pulmonry complictions (n = 207) Pulmonry compliction Frequency Difficulty in brething requiring intervention 40 (19.3) Pneumoni 11 (5.3) Trcheobronchitis 8 (3.9) Desturtion (Spo 2 < 90%) 7 (3.4) Reintubtion 7 (3.4) Atelectsis 3 (1.3) Pleurl effusion 2 (0.97) Pneumothorx 2 (0.97) ARDS 2 (0.97) Abbrevition: ARDS, cute respirtory distress syndrome. Dt shown s number (%) of ptients. The results of multivrite nlysis re shown in Tble 6. In multivrite nlysis, only preopertive respirtory bnormlity, cervicl lminectomy nd instrumenttion surgery, nd postopertive mechnicl ventiltion of > 24 hours were found to be independent risk fctors for PPC. Discussion We conducted this retrospective study to find out the incidences nd nture of vrious pulmonry complictions nd the ssocited risk fctors in ptients who underwent cervicl spine surgery. The incidence of PPC in our study ws 39.6%. The most common pulmonry compliction ws difficulty in brething requiring some intervention (19.3%). The reported incidence of PPC fter vrious procedures vries between 2.5 nd 37% This lrge vrition in the incidence of PPCs cn be scribed to differences in different definitions used for pulmonry complictions, preopertive ptient s conditions, types of surgery, nd durtion of postopertive follow-up. Our definition of PPC ws more inclusive becuse, in ddition to specific pulmonry pthologies, such s pneumoni, telectsis, nd ARDS, it included nonspecific pulmonry conditions such s respirtory distress or hypoxemi tht lwys cnnot be ttributed to ny specific pulmonry pthology nd cn led to life-thretening situtions nd needs urgent intervention. We found higher incidence of PPCs becuse of the inclusion of nonspecific pulmonry conditions such s difficulty in brething requiring intervention. Preopertive respirtory system bnormlity ws present in 34 (16.4%) ptients in our study, nd we found it to be n independent risk fctor for PPC (OR, 6.8; 95% CI [2.9, 15.9]; p < ). Studies hve demonstrted preopertive respirtory bnormlity to be ssocited with incresed risk of pulmonry compliction. 16,17 Chronic obstructive pulmonry disese (COPD) is one of the most importnt risk fctors for PPC. Ptients with severe COPD re more likely to hve PPC, nd COPD ws found to be n independent predictor of incresed mortlity in ptients undergoing crdic surgeries. 18 Lminectomy nd instrumenttion surgery ws lso n independent risk fctor for PPC in our study. This could lso be explined on the bsis of posterior surgicl pproch used in these surgeries. Tni et l compred the reltive sfety of nterior corpectomy (nterior pproch surgery) versus lminoplsty (posterior pproch) surgery. As compred with lminoplsty, ptients treted with corpectomy were noted to hve significntly better functionl results nd no postopertive neurologicl complictions. Ptients treted with lminoplsty were noted to hve significnt neurologicl deteriortion. 19 In ddition, posterior pproch for cervicl pthologies is reported to be ssocited with incresed risk for infection, incresed postopertive neck pin, nd postlminectomy kyphosis. 20 Postopertive pin my impir ptient s bility to cough in the postopertive period, leding to retention of pulmonry secretion cusing pulmonry infection. Hence this might hve contributed towrd n incresed incidence of PPC in ptients who underwent lminectomy nd instrumenttion surgery Durtion of postopertive mechnicl ventiltion of > 24 hours ws nother independent risk fctor for PPC in our study (OR, 43.2; 95% CI [5.5, 337.1]; p < ). Trchel tubes re known conduits for lower irwy contmintion nd cn led to chest infection. Greter durtion of postopertive mechnicl ventiltion might hve predisposed ptients to PPC, leding to higher incidence of PPC in those ptients. Volutrum nd brotrums ssocited with mechnicl ventiltion is thought to generte physicl dmge s well s pulmonry inflmmtory response leding to pulmonry dysfunction. 21 Postopertive mechnicl ventiltion is known to increse the chnce of PPC in ptients fter spine surgery. 22 In our study, ptients with PPCs hd significntly longer ICU sty thn those who did not hve PPCs ( Tble 4). In ptients with cervicl spinl cord injury, length of hospitl sty nd hospitl costs were reported to increse with the number of respirtory complictions experienced during the hospitliztion. 23 The mjor limittion of our study is tht it is retrospective study. We my hve missed mny cses becuse of indequte dt recording. We hd no dt bout the prend postopertive pulmonry function tests of the ptients, which could hve dded to our understnding of PPCs. Mny of these limittions cn be minimized with prospective Journl of Neuronesthesiology nd Criticl Cre Vol. 5 No. 2/2018

5 102 Tble 4 Comprison of different vribles in ptients with nd without PPC (n = 207) Prmeter Group P (n = 82) Group A (n = 125) p- Vlue Age (y) b 47.5 ± ± Sex Mle 66 (80.4) 101 (80.8) Femle 16 (19.6) 24 (19.2) Weight (kg) b 58.9 ± ± ASA sttus I 38 (46.3) 74 (59.2) II 42 (51.2) 51 (40.8) III 2 (2.5) 0 IV 0 0 Smoking 24 (29.2) 20 (16) 0.02 Respirtory bnormlity 26 (31.7) 8 (6.4) Dignosis PIVD 23 (28) 59 (47.2) SOL 18 (21.9) 13 (10.4) Myelopthy 12 (14.6) 25 (20) others 29 (35.5) 28 (22.4) Level Upper 8 (9.8) 5 (4) Middle 18 (22) 28 (22.4) Lower 30 (36.6) 59 (47.2) Multiple 26 (31.7) 33 (26.4) Approch Anterior 32 (39) 73 (58.4) Posterior 48 (58.5) 52 (41.6) Combined 2 (2.5) 0 Surgery ACDF 18 (21.9) 63 (50.4) Lminoplsty 38 (46.3) 43 (34.4) Lminectomy nd instrumenttion 26 (31.7) 19 (15.2) Durtion of surgery (min) b ± ± < Durtion of nesthesi (min) b ± ± 70.6 < Blood loss (ml) b ± ± < Fluid (ml) b ± ± Trcheostomy Yes 5 (6.1) 0 No 77 (93.9) 125 (100) Methyl prednisolone use Yes 15 (18.5) 9 (7.2) No 67 (81.5) 116 (92.3) Mechnicl ventiltion (h) b 32 ± ± 3.64 < ICU sty (h) b 62.5 ± ± 8.3 < Hospitl sty (d) b 7.6 ± ± 2.6 < Abbrevitions: ACDF, nterior cervicl discectomy nd fusion; ASA, Americn Society of Anesthesiologists; ICU, intensive cre unit; PIVD, prolpsed intervertebrl disc; PPC, postopertive pulmonry compliction; SOL, spce-occupying lesions. Dt shown s number (%) of ptients unless specified. b Dt shown s men (±SD) Journl of Neuronesthesiology nd Criticl Cre Vol. 5 No. 2/2018

6 103 Tble 5 Univrite nlysis of reltive risk for PPC (n = 207) Prmeters Group P (n = 82) Group A (n = 125) OR 95% CI p- Vlue Age (y) (23.2) 25 (20.0) (47.5) 84 (67.2) 0.61 (0.3, 1.2) > (29.3) 16 (12.8) 1.97 (0.8, 4.7) Smoking No 58 (70.8) 105 (84) 1.0 Yes 24 (29.2) 20 (16) 2.17 (1.1, 4.2) Respirtory bnormlity No 56 (68.3) 117 (93.6) 1.0 Yes 26 (31.7) 8 (6.4) 6.8 (2.9, 15.9) Dignosis PIVD 23 (28) 59 (47.2) 1.0 SOL 18 (21.9) 13 (10) 3.55 (1.5, 8.4) Myelopthy 12 (14.6) 25 (20) 1.23 (0.5, 2.8) Others 29 (35.5) 28 (22.4) 2.65 (1.3, 5.4) Approch Anterior 32 (39) 73 (58.4) 1.0 Posterior 48 (58.5) 52 (41.6) 2.1 (1.2, 3.7) Combined 2 (2.4) 0 Surgery ACDF 18 (21.9) 63 (50.4) 1.0 Lminoplsty 38 (46.3) 43 (34.4) 3.0 (1.6, 6.1) Lminectomy nd instrumenttion 26 (31.7) 19 (15.2) 4.8 (2.2, 10.5) Durtion of nesthesi (min) 180 min 8 (9.8) 31 (24.8) min 41 (50) 72 (57.6) 2.2 (0.9, 5.2) > 300 min 33 (40.2) 22 (17.6) 5.8 (2.2, 14.9) Blood loss 500 ml 61 (74.4) 113 (90.4) 1.0 > (25.6) 12 (9.6) 5.4 (2.4, 12.5) Intrvenous fluid 2, (34.2) 68 (54.4) 1.0 > 2, (65.8) 51 (45.6) 2.3 (1.3, 4) Methyl prednisolone No 67 (81.5) 116 (92.8) 1.0 Yes 15 (18.5) 9 (7.2) 2.9 (1.2, 7) Mechnicl ventiltion 24 h 25 (30.5) 3 (2.4) 1.0 > 24 h 16 (19.5) 1 (0.8) 43.2 (5.5, 337.1) < < < < Abbrevitions: ACDF, nterior cervicl discectomy nd fusion; CI, confidence intervl; OR, odds rtio; PIVD, prolpsed intervertebrl disc; PPC, postopertive pulmonry compliction; SOL, spce-occupying lesions. Dt shown s number (%). Journl of Neuronesthesiology nd Criticl Cre Vol. 5 No. 2/2018

7 104 Tble 6 Multivrite nlysis of PPC Prmeters OR 95% CI Respirtory bnormlity 5.4 (1.8,16.6) Lminectomy nd instrumenttion 8.35 (1.9,37.3) Mechnicl ventiltion (> 24 h) 51.3 (5.4,489) Abbrevitions: CI, confidence intervl; OR, odds rtio; PPC, postopertive pulmonry compliction. study. Despite these limittions, our study showed tht PPCs re common in ptients with cervicl spine pthologies, which cn prolong the durtion of ICU nd hospitl sty. Conclusion Ptients with cervicl spinl cord pthology re t incresed risk for PPCs. There is strong ssocition between PPCs nd preopertive respirtory bnormlity, postopertive mechnicl ventiltion > 24 hours, nd cervicl lminectomy nd instrumenttion surgery. Ptients with PPC hd significntly longer ICU nd hospitl sty. Future lrge prospective studies cn substntite our findings nd provide more useful informtion on PPCs in ptients with cervicl spine pthologies. Funding None. Conflict of Interest None. References 1 Lhuert J, Buxton P, Lipton S, Bowsher D. The loction nd function of respirtory fibres in the second cervicl spinl cord segment: respirtory dysfunction syndrome fter cervicl cordotomy. J Neurol Neurosurg Psychitry 1992;55(12): Rosomoff HL. Occult respirtory nd utonomic dysfunction in crniovertebrl nomlies nd upper cervicl spinl disese. Spine 1986;11(4): Toyod H, Nkmur H, Konishi S, Teri H, Tkok K. Does chronic cervicl myelopthy ffect respirtory function? J Neurosurg Spine 2004;1(2): Wdi NH. Myelopthy complicting congenitl tlnto-xil disloction. (A study of 28 cses. Brin 1967;90(2): Smith PH, Benn RT, Shrp J. Nturl history of rheumtoid cervicl luxtions. Ann Rheum Dis 1972;31(6): Tggrd DA, Trynelis VC. Mngement of cervicl spinl frctures in nkylosing spondylitis with posterior fixtion. Spine 2000;25(16): Swin PD, Trynelis VC. Posterior rticulr mss plte fixtion of the sub-xil cervicl spine. In: Menezes AH, Sonntg VKH, eds. Principles of Spinl Surgery. New York, NY: McGrw-Hill; 1996: Mitchell CK, Smoger SH, Pfeifer MP, et l. Multivrite nlysis of fctors ssocited with postopertive pulmonry complictions following generl elective surgery. Arch Surg 1998;133(2): McAlister FA, Bertsch K, Mn J, Brdley J, Jck M. Incidence of nd risk fctors for pulmonry complictions fter nonthorcic surgery. Am J Respir Crit Cre Med 2005;171(5): Hll JC, Trl RA, Hll JL, Mnder J. A multivrite nlysis of the risk of pulmonry complictions fter lprotomy. Chest 1991;99(4): Brooks-Brunn JA. Predictors of postopertive pulmonry complictions following bdominl surgery. Chest 1997;111(3): Avendno CE, Flume PA, Silvestri GA, King LB, Reed CE. Pulmonry complictions fter esophgectomy. Ann Thorc Surg 2002;73(3): Fuso L, Cisternino L, Di Npoli A, et l. Role of spirometric nd rteril gs dt in predicting pulmonry complictions fter bdominl surgery. Respir Med 2000;94(12): Hoyt DB, Simons RK, Winchell RJ, et l. A risk nlysis of pulmonry complictions following mjor trum. J Trum 1993;35(4): Roukem JA, Crol EJ, Prins JG. The prevention of pulmonry complictions fter upper bdominl surgery in ptients with noncompromised pulmonry sttus. Arch Surg 1988;123(1): Lwrence VA, Dhnd R, Hilsenbeck SG, Pge CP. Risk of pulmonry complictions fter elective bdominl surgery. Chest 1996;110(3): McAlister FA, Khn NA, Strus SE, et l. Accurcy of the preopertive ssessment in predicting pulmonry risk fter nonthorcic surgery. Am J Respir Crit Cre Med 2003; 167(5): Fuster RG, Argudo JA, Albrov OG, et l. Prognostic vlue of chronic obstructive pulmonry disese in coronry rtery bypss grfting. Eur J Crdiothorc Surg 2006;29(2): Tni T, Ushid T, Ishid K, Ii H, Noguchi T, Ymmoto H. Reltive sfety of nterior microsurgicl decompression versus lminoplsty for cervicl myelopthy with mssive ossified posterior longitudinl ligment. Spine 2002;27(22): Herkowitz HN. A comprison of nterior cervicl fusion, cervicl lminectomy, nd cervicl lminoplsty for the surgicl mngement of multiple level spondylotic rdiculopthy. Spine 1988;13(7): Dreyfuss D, Sumon G. Ventiltor-induced lung injury: lessons from experimentl studies. Am J Respir Crit Cre Med 1998;157(1): Stundner O, Ther F, Pwr A, Memtsoudis SG. Pulmonry complictions fter spine surgery. World J Orthop 2012;3(10): Winslow C, Bode RK, Dn Felton D, Chen D, Meyer PR Jr. Impct of respirtory complictions on length of sty nd hospitl costs in cute cervicl spine injury. Chest 2002;121 (5): Journl of Neuronesthesiology nd Criticl Cre Vol. 5 No. 2/2018